LEVEL SENSOR FOR DETECTION OF THE LEVEL OF A MEDIUM CONTAINED IN A RESERVOIR, METHOD FOR CONTROLLING

专利摘要:
sensor for detecting the level of a medium. the present invention relates to a level sensor for detecting the level of a medium contained in a reservoir, in particular a tank, comprising: a set of capacitive elements designed to be associated with the reservoir (1), in particular, to extend according to a geometric detection axis (x) of the middle level (1), the set of capacitive elements comprising a plurality of electrodes (j1-jn), in particular, on a face of an electrically insulating substrate ( 20) which has a generally elongated shape, the electrodes (j1-jn) being spaced apart, in particular along the geometric detection axis (x), and preferably being essentially coplanar with each other, at least one insulation layer (16) for electrically insulating the electrodes (j1-jn) from the inner side of the reservoir (1), a controller (24) having a plurality of inputs. each capacitive element comprising at least one of a unit electrode and a group of electrodes connected to each other, particularly in parallel, the unit electrode or group of electrodes being connected to a respective input of the plurality of inputs. the controller (24) being preconceived to discriminate an electrical capacitance value associated with each electrode (j1-jn) to deduce the level of the medium present in the reservoir.
公开号:BR112016027345B1
申请号:R112016027345-1
申请日:2015-05-28
公开日:2021-08-03
发明作者:Matteo Rondano；Enrico Chiesa；Mauro Zorzetto；Domenico Cantarelli
申请人:Eltek S.P.A；
IPC主号:

专利说明:

DESCRIPTIONField of the Invention
[001] The present invention relates to a sensor for detecting the level of a generic medium, such as a liquid, fluid substance, a powder or solid state material, etc. The invention was developed with particular reference to the capacitive type level sensors used in vehicles. State of the Art
[002] Level sensors are used in various fields to detect a residual amount of a liquid present in a generic reservoir, such as a tank. Some of these sensors are based on the use of a float. These sensors are often mechanically complicated and present certain problems, such as the risk of clogging. These sensors are inevitably affected by issues related to a possible freezing of the medium being measured.
[003] It is also known that level sensors are based on the measurement of electrical quantities, such as conductivity/resistivity or electrical capacitance. These sensors usually have a set of first electrodes, arranged according to the geometric axis of level detection - usually vertical - on a corresponding insulating support intended to be mounted inside the tank. The sensors also have a similar set of second electrodes, interposed or facing the electrodes of the first set, so that the fluid being measured can seep between the electrodes of the two sets. In some solutions, in place of a plurality of second electrodes, a common electrode is provided, at a height at least equal to the height of the first set. In other solutions, it is the tank itself that has an internal surface made electrically conductive, for example, by means of surface metallization, in order to serve as a common electrode. The electrodes are electrically connected to a circuit arrangement, often including a microcontroller, which, when processing the value of the electrical quantity detected between the electrodes, is able to detect a transition zone between liquid and air in the tank, considered indicative of the liquid level.
[004] In these known solutions, the electrodes are directly in contact with the liquid and, therefore, subjected to premature wear and deterioration. The operation of these sensor systems is also closely related to fluid characteristics, such as its conductivity/resistivity or its dielectric constant.
[005] With reference to capacitive-type level sensors, these typically provide at least two electrodes facing each other, between which the liquid for height detection is intended to infiltrate, with these electrodes being energized by a circuit oscillator that generates an alternating electrical signal or a frequency modulated signal. The circuit will detect a capacitance variation between the opposing electrodes, which is proportional to the dielectric variation interposed between the electrodes or proportional to the level of the interposed liquid and, thus, to the electrical capacitance of the sensor element. In these sensors, an output signal is therefore obtained which is proportional to said capacitance change. Known sensors of this type involve configurations with the respective impedance, which can also act as antennas, which causes the problem of generating electromagnetic noise (EMI), which noise is prone to interfere with other electronic systems, such as the vehicle's electronic circuits . This phenomenon intensifies with increasing length of electrodes or increasing length of the level sensor, which could act as a transmit antenna.
[006] Additional types of capacitive sensors involve a measurement between at least two coplanar electrodes, for example, with an interdigitated configuration, which face towards an insulating wall that separates them from the liquid, where the presence of liquid in the insulating wall causes a variation of the dielectric material between the two electrodes arranged side by side, thus allowing its detection. Such a sensor is known, for example, from US 7258005 B2. In these cases, the spacing between the two electrodes must be much greater than the insulating wall thickness, typically greater than twice the wall thickness (or the sum of the wall thicknesses interposed between each of the two electrodes and the fluid to be detected) in such a way that any liquid can effectively destabilize the capacitance between the electrodes. In addition to creating spending problems, this type of solution has limitations in measurement resolution or accuracy.
[007] Other types of capacitive sensors are mounted on the outside of a tank, such as a fuel tank or an additive tank on a vehicle. These types of sensors are, however, penalized by the fact that the tank must provide large wall thicknesses in order to guarantee the necessary mechanical strength, which involves the need to use signals with higher power frequency to detect the liquid level in the tank, thus creating a greater risk of occurrence of the aforementioned electromagnetic noise.
[008] The document US 2005/280424 A1 describes a level sensor that has a set of capacitive elements, which comprises a plurality of electrodes spaced from each other along a geometric detection axis and substantially coplanar with each other. The sensor also comprises a measuring device, preconceived to measure a capacitance value between a first electrode, considered as a measuring electrode and a second electrode, considered as a counter electrode. Summary and Objectives of the Invention
[009] In general terms, the present invention aims to obtain a simple and economical construction level sensor, which is distinguished by a high flexibility of use and production and which is essentially free from the problems highlighted above.
[0010] According to a first aspect, the invention aims to obtain a level sensor that can be manufactured in different lengths, while ensuring its accuracy and reliability.
[0011] According to a different aspect, the invention proposes to obtain a sensor that is suitable for carrying out level measurements even in conditions of solidification or at least partial freezing of the medium to be measured.
[0012] According to a different aspect, the invention aims to obtain a level sensor capable of distinguishing the presence and/or height of different layers and/or different states of the medium subjected to detection, such as a sequence of states and/ or "liquid - air or gas - solid" layers or a "liquid - solid" sequence or a "air or gas - solid" or "liquid - air or gas" sequence.
[0013] According to a different aspect, the invention aims to obtain a level sensor capable of detecting variations in the height of the different layers and/or states of the medium subjected to detection, such as an increase or decrease in a frozen or solidified layer of the means, for example, a measurement of changes in level in a tank containing a liquid, during a freezing and/or de-icing step.
[0014] According to a different aspect, the invention aims to obtain a level sensor provided with a structure that allows its precise operation, even when affected by stresses due to freezing and/or solidification and/or heating conditions of the medium subjected to detection.
[0015] At least one of the objectives of the invention is achieved by means of a level sensor and a method of controlling it, which has the characteristics of the appended claims. The claims form an integral part of the technical description provided herein in relation to the invention. Brief Description of Drawings
[0016] Other objectives, characteristics and advantages of the invention will become apparent from the following description, with reference to the attached drawings, provided simply by way of a non-limiting example, in which:
[0017] - Figures 1 and 2 are partially sectioned, schematic and perspective views of two possible alternative configurations for mounting a level sensor, according to the invention, on a generic reservoir, such as a tank;
[0018] - Figures 3 and 4 are schematic views in perspective, from different angles, of a level sensor according to an embodiment of the invention;
[0019] - Figure 5 is a partially sectioned, schematic and perspective view of a level sensor according to a possible embodiment of the invention;
[0020] - Figure 6 is a partially exploded schematic view of a level sensor according to a possible embodiment of the invention;
[0021] - Figures 7 and 8 are schematic views in perspective, from different angles, of a circuit of a level sensor according to a possible embodiment of the invention;
[0022] - Figure 9 is a cross-sectional, longitudinal and schematic view of a level sensor according to a possible embodiment of the invention;
[0023] - Figure 10 is a first enlarged-scale detail of Figure 9;
[0024] - Figure 11 is an enlarged-scale detail of Figure 10;
[0025] - Figure 12 is a second enlarged-scale detail of Figure 9;
[0026] - Figure 13 is a schematic and cross-sectional view of a sensing portion of a level sensor according to a possible embodiment of the invention;
[0027] - Figure 14 is an enlarged-scale detail of Figure 13;
[0028] - Figure 15 is an enlarged-scale detail of Figure 14;
[0029] - Figures 16, 17 and 18 are partial and schematic perspective views of possible alternative configurations for mounting or fixing a level sensor according to a possible embodiment of the invention;
[0030] - Figure 19 is a partial and schematic perspective view of a portion of a reservoir to which a level sensor according to Figure 18 can be associated;
[0031] - Figure 20 is a partial and schematic representation intended to illustrate a possible configuration to connect the electrodes of a level sensor according to a possible embodiment of the invention;
[0032] - Figure 21 is a partial and schematic representation intended to exemplify a possible configuration of the circuit of a level sensor according to Figure 20;
[0033] - Figure 22 is a partial and schematic representation similar to Figure 21, designed to exemplify a possible alternative configuration of the circuit of a level sensor according to Figure 20;
[0034] - Figures 23 and 24 are schematic representations designed to illustrate other possible configurations for connecting the electrodes of the level sensors according to possible alternative embodiments of the invention;
[0035] - Figure 25 is a partial and schematic representation designed to exemplify a possible configuration of the circuit of a level sensor according to Figure 24;
[0036] - Figure 26 is a schematic graphical representation, designed to exemplify a possible interpretation principle of the electrical signals or values used in the possible embodiments of the invention;
[0037] - Figures 27 and 28 are schematic representations similar to those of Figures 20, 23 and 24, designed to illustrate other possible configurations for connecting the electrodes of the level sensors according to possible alternative embodiments of the invention;
[0038] - Figure 29 is a schematic representation of some elements of the circuit of a level sensor according to a possible embodiment of the invention;
[0039] - Figure 30 is a partial and schematic representation similar to that of Figure 25, designed to exemplify another possible use condition of a level sensor according to a possible embodiment of the invention; and
[0040] - Figure 31 is a partially sectioned, schematic and perspective view of a possible variant of modality of a level sensor according to the invention. Description of Preferred Embodiments of the Invention
[0041] Reference made to "an embodiment" throughout this description indicates that a particular configuration, structure or feature described in relation to the embodiment is included in at least one embodiment. Therefore expressions such as "in one modality" and the like, possibly presented in different parts of this description, do not necessarily refer to the same modality, but rather to different modalities. Furthermore, particular conformities, structures or characteristics defined throughout this description may be combined in any suitable way in one or more embodiments, which may even be different from those illustrated. Numerical and spatial references (such as "top", "bottom", "top", "bottom", "front", "back", "vertical", etc.) used here are for convenience only and therefore do not define the field of protection or the scope of the modalities. In the figures, the same reference numerals are used to indicate elements that are similar or technically equivalent.
[0042] In Figure 1, reference 1 indicates as a whole a generic reservoir, particularly a tank, for a generic fluid medium or in a bulky state. Tank 1 has a main body, preferably formed of an electrically insulating plastic material. A heater of the type known per se can possibly be associated with tank 1, which is used to heat the tank itself and/or its contents, for example in the case of freezing. An electric heater is shown schematically in the Figures by the block indicated by EH.
[0043] Tank 1 can be, for example, a tank that equips a motor-powered vehicle. In one embodiment, such as that exemplified here, tank 1 is intended to equip a vehicle with a diesel engine and the liquid contained in tank 1 is a liquid known as AdBlue, which is a 32.5% solution and urea (minimum 31.8% - maximum 33.3%) in demineralized water, used by a SCR (Selective Catalyst Reduction) system, that is, a system to reduce the emissions of nitrogen oxides from the exhaust gases produced by a diesel engine.
[0044] In the example illustrated schematically, the tank has an upper wall 2, in which an opening, provided with a lid 3 for covering the liquid, is provided. A wall of tank 1, for example its bottom wall 4, has a non-visible outlet opening through which liquid flows or is aspirated, for example using a pump, to introduce liquid into the SCR system . Still on the top wall 2, the tank 1 has a second opening, indicated by 5, in which the body of a level sensor is fixed in a sealed manner, according to a possible embodiment. The level sensor, denoted as a whole by 10, is mounted to extend along a geometric level sensing axis, denoted by X, preferably essentially vertically but possibly tilted to the vertical direction. , if necessary.
[0045] The sensor 10 has a sensing part 11, intended to extend at least partially inside the tank 1. The distal end region of the sensing part 11 is preferably in contact with or at a small distance from the bottom wall 4 of the tank. , that is, at a height very close to the height of the liquid outlet or suction opening, in order to also be able to detect the presence of a very low level in the tank. In a non-illustrated embodiment, the distal end region of the sensing part 11 is fixed internally to the wall of the tank 1 opposite the wall provided with the opening 5 for the insertion and fixation of the sensor 10, preferably by means of a coupling or a quick-release insert fixture. Preferably, the proximal end region of the sensing part 11 extends into the tank 1 at a height relatively close to the top wall 2.
[0046] In the illustrated mode, the sensor body 10 has, in its upper part, elements for the fixation itself of the upper wall 2 of the tank. In the example, these means are represented by flange formations with associated bolts, not indicated. This modality should not, however, be considered limiting, as different solutions for fixing the sensor body 10 are also possible, some of which will be illustrated below.
[0047] In the example of Figure 1, the sensor 10 is fixed from its top or is associated with the upper wall 2 of the tank. In other embodiments, however, the sensor can be attached from its bottom or from the bottom wall 4. One such embodiment is illustrated schematically in Figure 2, in which the sensor 10 is sealingly mounted in the opening 5, here defined on the bottom wall 4. In this embodiment, a region of the proximal end of the sensing part 11 (here defined as lower) is also in a position close to the lower wall 4, while the region of the distal end (here defined as upper) meets itself at a height relatively close to the top wall 2. In such a solution, the distal end of the part 11 can be fixed to the wall 2 by suitable coupling means of the type indicated above.
[0048] In Figures 3 and 4, a sensor 10, according to a modality, is represented separately, from different angles. At the proximal end of part 11, the body 10a of the sensor 10 defines a box-shaped housing 12, which also includes a generally concave connector body 12a, provided with electrical terminals as indicated below, preferably protruding from of a side wall of the housing. Housing 12 is preferably provided with a closure cap 13, which can be secured in a sealed position, for example by means of a weld between the plastic material of housing 12 and cap 13.
[0049] Between the housing 12 and the part 11, the body 10a of the sensor 10 preferably defines a portion or formation 14 for a sealed coupling in the respective mounting opening on the tank. Formation 14 defines at least one base for at least one sealing element 15, which can also possibly fulfill the function of elastic mounting of the sensor 10 with respect to the tank. In one embodiment, at least two elastic ring-type elements are provided, one of which fulfills the sealing function and the other is used to obtain an elastic mounting of the sensor 10 on the tank 1, for example, for compensation purposes assembly tolerances. In the illustrated example, formation 14 has an essentially circular profile and the sealing element is a ring-type seal. In Figures 3 and 4, the flange formations mentioned above for the attachment of the sensor body 10a are indicated by 12b, defined here at the bottom of the housing 12.
[0050] In Figure 5, a sensor 10 according to an embodiment is represented in a partially sectioned way, in order to highlight how its body 10a is internally concave to house the components of the level detection. From this figure, it can be particularly seen how the sensor body 10a defines, in the sensing part 11, a concave casing 16, of generally elongated shape. In the illustrated example, the casing 16 has a generally prismatic shape, in particular, essentially parallelepiped shape. As will be seen in a variant of embodiment, at least the housing 16 can be produced using the technique of direct overmolding of an electrically insulating plastic material onto a circuit support, which is described hereinafter. More commonly, sensor 10 has at least one insulating layer to electrically insulate its electrodes (described later here) from the inner side of tank 1.
[0051] In a preferred embodiment, housing 12 with formation 14 and housing 16 are defined by a unitary body 10a of electrically insulating plastic material, as is clearly visible, for example, in Figure 6. In addition, one embodiment is also included in the invention, whereby the body 10a has its discrete parts secured together in a sealed manner, for example by means of mutual coupling or by welding or overmolding.
[0052] In one embodiment, the body 10a, or at least the portion thereof intended for direct or indirect exposure to the liquid (to the shell 16 and possibly to the attachment portion 14), is formed of a moldable thermoplastic material, such as polypropylene (PP) or by a high density polyethylene (HDPE). Practical tests carried out by the depositor allowed, however, the finding that a particularly suitable material, also depending on the particular modes of level detection described hereafter, is a cycloolefin copolymer (COC - Cyclic Olefin Copolymer). Materials of this type - generally used in the medical field - have particularly advantageous characteristics for the application considered here, among which the following should be highlighted: low density, extremely low water absorption, excellent barrier properties against water vapor, high rigidity , strength and hardness, high resistance to extreme temperatures and thermal shock, excellent resistance to corrosive agents such as acids and alkalis, excellent electrical insulation properties, simple processing through the use of common methods of treatment of thermoplastic materials such as such as injection molding, extrusion, blow molding, injection blow molding.
[0053] The material or at least one of the materials used in the production of the body 10a of the sensor 10, may be similar or chemically compatible with the material that forms at least part of the tank 1, for example, in order to allow a sealed weld between the sensor body and tank. One or more of the materials mentioned above are usable for producing different portions of the body 10a, such as the housing 12 with the formation 14 and the housing 16, even when the body 10a is formed of separate parts that become integral with one another. others. Obviously, the lid 13 can also be made from one of the materials indicated.
[0054] Still referring to Figure 5, it can be seen that the electrical and electronic detection components are housed in a cavity defined by the sensor body 10 - indicated here as a whole by H. In a preferred embodiment, these components are mounted on top an electrically insulating substrate 20 that forms a support for the circuit. The support 20 is formed of a material suitable for the production of printed circuit boards, such as, for example, FR4 or a similar composite material, such as fiberglass or a ceramic or polymer-based material, preferably , a moldable material for the purpose of producing the support 20.
[0055] In the support of circuit 20, a first portion 20a is defined, which is designed to be received in housing 12, and a second portion 20b, designed to be received within housing 16. The control electronics of the sensor 10 are predominantly associated with the portion 20a of the support 20, as well as the corresponding terminals for the external electrical connection of the sensor 10; the detection components are already associated with the portion 20b of the support 20, which includes a series of electrodes; some of said electrodes being indicated in Figure 5 by the letter "J", followed by the number that identifies the position of the electrode in the series extending from the proximal end (electrode J1) to the distal end (electrode Jn) of the sensing part 11 or portion 20b of support 20.
[0056] In the illustrated example, a unitary circuit support is provided, in which parts 20a and 20b are defined, however, in possible variant embodiments, more circuit supports can be provided, connected by suitable means of electrical interconnection and possibly by mechanical interconnecting means (e.g. a circuit support corresponding to portion 20a and a circuit support corresponding to portion 20b, with electrical conductors or connectors for connecting the electrically conductive rails of the portion to the electrically conductive rails of the other portion).
[0057] In Figure 6, a sensor 10 according to an embodiment of the invention is represented by means of an exploded view, from which the various parts already identified above are detectable. In this figure, the terminals mentioned above are visible, indicated by 21, preferably with a generally flat shape, for example, made by molding and/or cutting from a metal strip, which obtain with the connector body 12a, which is integral with the housing 12, an interface for the external connection of the sensor 10, for example, with a control unit of the vehicle's SCR system
[0058] In one embodiment, each terminal 21 has a laminated contact portion 21a, intended to be positioned within the connector body cavity 12a, and a narrow interconnection portion 21b, intended for electrical and mechanical coupling with the respective contacts 22 located on the support 20, particularly in its portion 20a, described hereinafter.
[0059] Still referring to Figure 6, the bracket 20 is visible as a whole, with its corresponding parts 20a and 20b, with the corresponding electrical and electronic components also being associated. The same support 20 is also shown separately in Figures 7 and 8 by way of opposing views of its main faces. The circuit support 20, generally elongated and preferably flat in shape, is associated with a control circuit arrangement, indicated as a whole by 23, on one of its main faces, here conventionally defined as "rear", An electronic controller 24, for example a microcontroller, is preferred. The controller 24 preferably comprises at least one processing and/or control logic unit, a memory circuit, as well as inputs and outputs, among which, analog/digital inputs.
[0060] The components of circuit arrangement 23 are connected to electrically conductive rails provided in portion 20a, visible, for example, in Figure 8, not indicated; a series of electrically conductive rails 25 is then provided at the rear of the bracket portion 20b for the electrical connection of the electrodes J of Figure 5, preferably with metallized holes for the connection between the rails on different surfaces, and other components possible to arrangement 23.
[0061] In one embodiment, the circuit comprises at least one temperature sensor, particularly provided on the corresponding circuit support 20. This sensor, for example, of the NTC type, can be mounted in at least one region within the region of the distal end and the proximal end region of portion 20b of bracket 20. In the illustrated example, on portion 20b of bracket 20, particularly at the rear, two temperature sensors 26 and 27 are mounted on opposite end regions of portion 20b connected to the circuit arrangement 23 by means of corresponding conductive rails. Considering the mounting of the sensor 10 on the tank 1, of the type illustrated in Figure 2, the temperature sensor 27 is usable for detecting the temperature of the liquid, while the sensor 26, which, in the assembled condition, is located more near the top wall of the tank, it can be used to detect the temperature of the tank's internal volume above the liquid, for example, the air temperature. The configuration of the type shown, in particular, with two temperature sensors 26 and 27, allows the mounting of sensor 10 in tank 1 both in the configuration in Figure 1 and in the configuration in Figure 2, inverting the functions, at the software level, such as as the functions of the two sensors and/or the functions of the electrodes J.
[0062] A sensor for the detection of temperature may possibly be provided within the portion 20a of the support or within the housing 12. It is obviously also possible to provide more than two temperature sensors, for example with one or more sensors in intermediate positions compared to sensors 26 and 27.
[0063] In Figure 8, the front part of the support 20 is clearly visible, in which the electrodes J are arranged in the portion 20b, only some of which are indicated. In the illustrated non-limiting example, electrodes J, equal in number to 37, are arranged according to an array that extends along a longitudinal direction of the support portion 20b or along the geometric detection axis X, spaced apart from one another. others. The electrodes J are formed of an electrically conductive material, for example a metallic material or a metallic alloy, and are associated with the front part of the portion 20b of the support 20. The electrodes J are preferably coplanar with each other and may have, for example, in the form of plates or sheets, or they can be engraved or applied on the support 20 or formed by an electrically-conductive layer, similarly to the rails 25, and deposited on the support 20, for example, by means of the screen printing technique or similar.
[0064] As mentioned in one embodiment, support 20 has hollow holes, partially visible in Figures 7 and 8, one of which is indicated by F, containing conductive material for the electrical connection between electrodes J provided on the front of portion 20b and the conductive rails 25 present at the rear of the same portion of the support 20.
[0065] In Figure 6, a part of the hidden cavity H is visible, which extends axially inside the body 10a of the level sensor or through its parts 12, 14 and 16. Inside this cavity H, the orientation and positioning elements of the support 20 are preferably provided, some of which are partially visible in Figures 5 and 6, in which they are indicated by 16a and 12c, respectively, in the housing 16 and in the housing 12. The positioning elements of the support 20 could also possibly be provided in cover 13.
[0066] In Figure 9, the level sensor 10 is visible in a longitudinal and cross section, where the presence of the hidden cavity H is clearly evident, which extends into the housing 12, the fastening formation 14, the housing 16 and circuit support 20 being housed in this cavity H. It becomes clearly evident from this Figure how in one embodiment, temperature sensor 27 is in a position close to formation 14, or generally in an assembled condition of sensor 10, in a position close to the wall of tank 1 provided with the sensor mounting opening 10. Furthermore, comparing Figures 7 and 8 with Figure 9, it becomes apparent that the electrode indicated by J1 is, in the assembled condition. of Figure 2, in a position close to the bottom wall of the tank, preferably in a position reachable by the liquid, even in a condition of minimal filling of the tank. As will be seen in one modality, electrode J1 is used to provide a reference value used during liquid level detection. In addition, one or more reference electrodes J may also be provided in other zones of the portion 20b of the support 20.
[0067] In Figure 9, the connector body 12a is also visible, with one of its terminals 21. The terminals 21 can be fitted with interference within corresponding passages defined in the connector body 12a, or possibly at least the housing body 12 can be overmolded on the terminals. Preferably, the terminals, and corresponding passages of the connector body, extend longitudinally in an essentially perpendicular direction with respect to a plane defined by circuit support 20 and/or electrodes J.
[0068] In one embodiment, the contacts 22 are configured for elastic coupling with the terminals 21, so as to obtain a mutual electrical and mechanical connection between them. In Figure 10 and in even greater detail in Figure 11, a possible mode of coupling is visible between portion 21b of a terminal 21 with a corresponding contact 22 provided on portion 20a of the bracket.
[0069] In the exemplified embodiment, see in particular Figure 11, the contacts have a flat base 22a provided with a hole or a central passage 22b from the base 22a, at least two flaps 22c that branch from opposite sides of the passage 22b, converging towards each other. The body of contacts 22 is formed of an electrically conductive material, such as a metal or a metal alloy, eg phosphor-bronze, preferably coated with tin, gold or other suitable material to enhance electrical contact.
[0070] The tabs 22c are inserted into a corresponding hollow hole 20c, defined in the support portion 20a, and the base 22a is fixed and/or welded to a surface of the support itself or to its conductive rails. Preferably, the orifice 20c is surrounded by the electrically conductive material of one of the circuit pattern tracks of the circuit arrangement 23 and with the base 22a of the contact 22, which is at least partially superimposed on said conductive material, so as to get the electrical connection. As also seen in Figure 11, in the assembled condition, the passage 22b of a contact is essentially aligned with the hole 20c of the support 20, with the base 22a resting against a surface of the support itself (in this case, the rear surface) and with tabs 22c which preferably protrude from hole 20c on the opposite surface (in this case, the front surface) of support 20.
[0071] For the purpose of mounting the sensor, the support 20, already provided with the corresponding electrical and electronic components, is inserted into the cavity H of the body 10a of the sensor 10 in its open part or in the housing 12. Accompanying this insertion, the portion 20b of support 20 is positioned primarily within housing 16, while portion 20a is positioned within housing 12. The position of contacts 22 and holes 20c on support 20 is such that, following the aforementioned insertion of the support 20 inside the body 10a, these holes and contacts face towards the internal passages of the body of the connector 12b. Terminals 21 are then interference fit within corresponding passages of connector body 12a so that respective interconnecting portions 21b penetrate holes 22a and 20c of contacts 22 and bracket 20, respectively. The portions 21b of the terminals are then inserted between the tabs 22c, causing an elastic gap, which ensures a proper electrical connection and a well-balanced mechanical connection. Preferably, this elastic electrical connection is also suitable to avoid any damage to the support 20 and the corresponding circuit, due, for example, to possible mechanical stresses that occur during the use of the sensor 10, such as vibrations or voltages applied to the terminals. 21.
[0072] It can be understood that the sensor assembly is very simple and easily automated, which involves elementary operations, consisting of the insertion of the circuit support 20 into the cavity H of the body 10a and the subsequent fitting of the terminals 21 into the corresponding passages of the connector body 12a.
[0073] As mentioned in one embodiment, the body 10a of the sensor 10 is provided with positioning and/or orientation elements for the support 20. The presence of these elements also simplifies the assembly of the sensor 10 and at the same time ensures a high precision of the assembly between parts and greater measurement accuracy. The aforementioned positioning elements can be provided in at least one housing 12 and housing 16, preferably both in housing and housing. As already mentioned, one or more positioning elements may be provided on the cover 13 of the housing 12.
[0074] With reference, for example, to Figures 10 and 11, in one embodiment, on the inside of each of the two opposite side walls of the housing 12, insertion and positioning guides are defined, indicated by 12c, generally parallel to each other. others and between which an edge region of the support 20 can be fitted, particularly in its portion 20a. In the illustrated example, guides 12c are defined as being elevated over the inner surface of the aforementioned opposite walls of housing 12 (see also reference made to Figure 6, in which the top of a guide 12c is visible), however, it is also provided for in the scope of the invention is an embodiment, in which guides with a purpose similar to that of guides 12c are formed by recesses, which extend in the longitudinal direction of the sensor body 10. Preferably, the top of guides 12c is shaped so as to have a centering guide, in this case defined by an inclined surface, configured to facilitate entry of the opposite edges of the support portion 20a into a respective pair of guides 12c. Portion 20a of bracket 20 can be inserted with slight interference between guides 12c or with minimal play.
[0075] From Figure 10, it is also visible how, in a preferred mode, the lid 13 also has, on the inside of its upper wall, a positioning formation 13a, defining a base for the proximal or upper edge (with reference to the figure) of portion 20a. Preferably, also in this case, the positioning formation 13a is shaped in such a way as to define a centering guide, which in this case includes two converging inclined surfaces, in order to facilitate the entry of the proximal or upper edge of the portion 20a inside the corresponding base when the cover 13 is mounted on the housing 12. The formation 13a preferably comprises a surface or a locking element 13b suitable for preventing unwanted axial movements of the support 20.
[0076] In a preferred embodiment, between the distal end of the housing 16 and the distal end of the bracket 20 (i.e., its portion 20a), a free space or gap is defined, particularly to allow compensation for possible different expansions between the material that forms the housing 16 and the material that forms the support 20. This gap is indicated by H1 in Figure 12, which represents an enlarged detail of Figure 9, particularly of the distal end portion of the sensor 10. To elucidate this aspect, a preferred field of use of sensor 10 is considered, the automotive sector, which predicts the occurrence of very low temperatures, for example, below -40°C, with the production of the device as opposed to what essentially occurs at room temperature , for example, 25°C. With reference to this numerical example, the sensor 10 is therefore subjected to considerable thermal oscillations, which cause shrinkage of the housing 16, which varies according to the plastic material used.
[0077] Using the hypothesis that there is such a temperature difference or delta of 65°C (from +25°C to -40°C), the gap H1 is therefore provided in order to allow the free contraction of the casing 16, without it coming into contact with the distal end or edge of support 20, and/or that gap H1 is provided so as to prevent said contraction of casing 16 from damaging one or more electrodes J. With reference to materials previously mentioned, the following thermal expansion values can be considered:- HDPE => 200 ppm/°C- PP => 120 ppm/°C- COC => 60 ppm/°C- FR4 (support 20) => 20 ppm /°C
[0078] Now, considering the formula H1 [mm] = unit h[mm/mm] x length Lu of the sensor [mm], for the thermal delta exemplified here (65°C), the following values of unit h can be considered: - h for HDPE =0.012mm/mm - h for PP =0.007mm/mm - h for COC =0.003mm/mm
[0079] Therefore, for example, for a sensor body 10 with Lu = 150 mm, made of HDPE, the minimum value of H1 is equal to 0.012 x 150 = 1.8 m; for a sensor body of identical length, with Lu made of PP, the minimum value of H1 equals 0.007 x 150 = 1.05 mm; for the same sensor body made of COC, the minimum value of H1 is equal to 0.003 x 150 = 0.45 mm.
[0080] In a preferred embodiment, the portion 20b of the support of the circuit 20 is positioned within the housing 16 of the body 10a of the level sensor in such a way that its front part or its face provided with electrodes J, is adjacent or supported against the corresponding inner surface, preferably at least partially in contact with it. To that end, preferably, within the housing 16, one or more positioning elements are provided which tend to push the support portion 20b towards a wall of the housing 16. In one embodiment, from the inner part from a wall of the casing 16, at least one said positioning element protrudes which extends towards the opposite wall of the same casing.
[0081] A possible modality for this purpose is shown in Figure 13, which represents a cross section of the casing 16 (particularly according to a plane orthogonal to the geometric axis X, passing, for example, along the line XIII-XIII of Figure 4). From this figure, it can be seen that, from the inside of one of the longer walls of the casing 16, two projections 16a protrude (one of which is also visible in Figures 5 and 9), generally parallel to each other and which extend in the longitudinal direction of the casing, preferably but not necessarily over its entire length (such projections could also have intermediate interruptions). Projections 16a, in this case defined integrally with body 10a or casing 16, preferably have a tapered profile so that their generally pointed or conical top is pressed against the rear of portion 20b of support 20. It is evident that, to accompany the insertion of the holder 20 into cavity H, the projections 16a are configured to press the front area of the part 20b against the inner surface of the wall of the housing 16 opposite the same, from which the projections themselves are raised. . This pressure advantageously has an elastic component, due to a certain elasticity of the plastic material forming the casing 16.
[0082] In one embodiment, the positioning element 16 or each positioning element 16 is formed of a material different from the material of the casing 16, such as an elastomer, for example, assembled or co-molded or overmolded in the casing 16 and /or having a different shape from that shown and at the same time being configured to operate under buoyancy and/or elastically on the support 20 and the electrodes J.
[0083] In a preferred embodiment, the projection or projections 16a are configured to be able to act elastically and/or deform, at least in its top region, in order to possibly allow the insertion of the support 20, even in the case where the thickness of the latter is greater than the distance between the tip of the projections 16a and the inner surface of the casing 16 that faces this tip (a condition that could occur under dimensional tolerances due to different shrinkage of the plastic material during the corresponding molding), and also thus, ensuring the aforementioned thrust.
[0084] In one embodiment, within the casing 16 or, in any case, at least between the support 20 and its corresponding front wall, the casing 16a - a fluid filling material - is introduced, which is not electrically conductive, of preferred way, to ensure the absence of air bubbles, particularly between electrodes J and housing 16, which could invalidate the correct level measurement, carried out according to the methods described below. The aforementioned filler material, which is preferably intended to encapsulate and/or be in contact with at least a portion 20b of the support 20, can be, for example, a polyurethane resin or, preferably, a gel, of most preferably, a silicone gel. A suitable silicone gel for this application is, for example, that known as SilGel® 612, marketed by the company Wacker Chemie AG, Monaco, Germany.
[0085] The presence of said gel mainly has the function of filling any gaps that may arise between the front of the portion 20b of the sensor and the wall of the casing 16 facing the same. These gaps, despite having a minimal volume, may exist, for example, due to the roughness of the surface of the support 20 and/or the J electrodes, or even when the J electrodes have a thickness that results in a slight projection from the surface front of the circuit support portion 20b, or again, due to roughness and/or possible deformation of the wall of the casing 16, for example, as a result of the surface finish of the corresponding mold and/or different shrinkage of the polymeric material and/ or thermoplastic, in the case of molding the casing 16.
[0086] The concepts highlighted above are also clarified by the details of Figures 14 and 15. In the detail of Figure 14, the top of the projection 16a is clearly visible, which presses the back of the support portion 20b, thereby pushing the electrodes - one of which is indicated by J - against the inner surface of the front wall of the housing 16. The other enlargement of Figure 15 shows the interface zone between the electrode J and the aforementioned wall of the housing 16, from which it is possible to detect as , in the exemplified case, the front surfaces of the two elements in question have respective micro-cavities, for example, due to surface roughness and/or material deformations (for example, different material shrinkage during molding, slight curvatures, etc.) . In the presence of the aforementioned gel - indicated by G in Figure 15, at the interface between the aforementioned micro-cavities - the projections 16a push the part 20b of the support 20 against the inner surface of the casing 16, thereby facilitating the discharge of excess gel existing between the two parts in question. Thus, between these front parts, only a film of gel G remains, which is strictly necessary to fill said micro-cavities. The above-mentioned discharge of excess gel G is preferably allowed by the presence of at least one exhaust chamber in housing 16, comprising, for example, the part of cavity H, inside housing 16, which is not occupied by support 20 or by the 16a projections. This chamber is schematically indicated by H2 in Figure 13 (possibly, chamber H2 may comprise the space previously indicated by H1).
[0087] From Figure 14, deformation or slight removal of material from above the projection 16a can also be observed, which in this example specifically gains a nominally rounded tip. As explained, the tapered shape of the projections 16a is intended to allow deformation, particularly in the case where the circuit support portion 20b is forcibly inserted into the cavity of the housing 16 (for example, in the case of excessive retraction or dimensional tolerances resulting from the molding of the casing itself), and to ensure the thrust mentioned above, in order to obtain a good contact between the electrodes J, and the inner surface of the casing 16, to remove excess gel, for the purpose of a reliable and accurate detection. In this regard, it is considered that, in the preferred embodiment, the gel is introduced into the cavity of the shell 16 in order to essentially fill it, however, for practical purposes, it is sufficient for the gel to be present at the interface between the portion. 20b of the holder with the electrodes J and the front surface of the housing 16, where excess gel can flow, as mentioned, into the aforementioned outlet chamber H2 located within the housing.
[0088] As already mentioned, the methods of fixing the body 10a of the level sensor 10 to the tank may be different from those previously exemplified here. In general, the coupling may be based on the presence of suspended elements associated with at least one of the sensor body 10a 10 and the tank 1, provided for coupling with the cavities or bases present in the tank 1 and the sensor body 10a, the coupling preferably taking place so as to follow a movement which is partly axial and partly angular. In one embodiment, the mechanical coupling between the body 10a and the tank is a quick coupling, for example a snap fit, a threaded coupling or a quick release insert. Figure 16, for example, exemplifies the case of coupling between sensor 10 and tank 1 based on the essentially bayonet coupling system. In this example, the sensor body 10a is provided, in its attachment portion 14, with a plurality of surface engaging teeth or projections, only one of which is visible, indicated by 12d, intended for coupling with the respective coupling bases 5a defined in peripheral positions with respect to the opening 5 of the wall of the tank 1 provided with the opening 5, in this case the bottom wall 4. Preferably, this wall of the tank 1 has, in the opening 5, a cylindrical housing for receiving of the fastening portion 14 and the corresponding seal 15, with the bases 5a extending between the upper face of the wall 4 and the cylindrical surface of the aforementioned housing. For the purpose of coupling, the body 10a is inserted through the opening 5, until the seal 15 rests on a corresponding contact surface defined in the aforementioned cylindrical housing, in which the fastening portion is also received. This insertion is carried out so that the projections 12d fit within an essentially vertical portion of the respective bases 5a. A subsequent angular movement applied to the body 10a determines the passage of the projections 12d through an essentially horizontal portion of the bases 5a, with a consequent coupling between the parts, which typically occurs in the type known as bayonet coupling (however, also being able to provide portions slanted on the bases 5a).
[0089] In one embodiment, coupling within the tank is additionally or alternatively provided, such as coupling based on coupling projections associated with at least one of the distal end of the sensor 10 and the front wall of the tank, projections coupling that fit with the cavities present in said distal end and in the wall. For example, the distal end of the housing 16 may be provided with one or more coupling projections or teeth, preferably radial projections, intended to couple the respective coupling bases defined in an element that is suspended from the tank wall. which faces said distal end. This coupling inside the tank may involve elements technically equivalent to those described with reference to the example in Figure 16.
[0090] The coupling of the type illustrated in Figure 16, in addition to not requiring specific tools, also allows obtaining an elastic assembly of the body 10a of the sensor 10 on the tank 1. In the embodiment of Figure 16, the shape of the housing 12 is essentially cylindrical, which does not affect its characteristics described above.
[0091] In one embodiment, the attachment between the body 10a of the level sensor and the tank 1 is of the permanent type, made, for example, by means of gluing or welding. Such a solution is exemplified in Figure 17, according to which, from the outside of wall 4 of tank 1 (but could also be wall 2) an annular projection 2a is raised, in this case an essentially quadrangular projection , which delimits a region of the wall 4 in which the opening 5 is defined, which in this case consists essentially of a slit with transverse dimensions that are slightly larger than those of the housing 16. In this case, the fixing portion 14 of the body 10a has a shape which is essentially complementary to the closed profile defined by the projection 2a, i.e. quadrangular in the illustrated example, and which is preferably provided with its own annular projection, a complementary or mirror image of the projection 2a, not shown. For the purpose of coupling, the housing 16 of the body 10a is inserted into the opening 5, until the fastening portion 14 engages with the projection 2a. The definitive fixation between portion 14 and projection 2a can be obtained through an adhesive deposited on at least one of the two parts in question (with a type of glue that also fulfills the sealing function) or through joint welding of portion 14 and of the 2a projection, for example, through a solder produced by laser, by vibrations or ultrasound, or even with the remelting of the material or of the defined type of hot rolling. Obviously, in this case, the materials forming the wall 2 or 4 of the tank 1 and the fixing portion 14 of the sensor body will be compatible materials in terms of welding.
[0092] In the embodiment of Figure 17, the housing wall 12 from which the connector body 12a protrudes and the connector body itself have a different structure compared to the cases previously illustrated, which does not affect the characteristics of the device described with reference to Figures 1-15. In Figures 16 and 17, the connection between the terminals located within the body of connector 12a and the internal circuitry of sensor 10 is also different from that previously exemplified. According to these variants, electrical connectors are preferably provided, equipped with a connector body 12a shaped so as to define the switching means, configured to allow univocal coupling with a respective external electrical connector, and/or with biasing means, configured only to allow coupling with said external connector in the current direction, thereby avoiding reverse polarity or incorrect connections.
[0093] Figure 18 illustrates a variant modality similar to that of Figure 16, however, distinct due to the presence of two elastic elements 15' and 15'', represented here by rings, with the fixation portion 14 defining the corresponding bases for these elements. Preferably, the surface-engaging projections 12c are defined on the portion 14 at an intermediate position with respect to the two elastic elements 15' and 15'', or at a position intermediate to the corresponding positioning bases. As shown in Figure 19, in such an embodiment, the cylindrical housing is formed in the mounting opening 5 so as to have two axial support surfaces 5b and 5c for the elements 15' and 15'', respectively, with the coupling bases 5a for the 12d projections, which are in an intermediate position to these surfaces.
[0094] In this mode, the bottom seal 15'', particularly a radial seal, performs the function of sealing the space between the portion 14 of the body 10a and the inner side of the corresponding cylindrical housing. In this case, the elastic element 15' is designed to be axially compressed between the corresponding support surface of the portion 14 - indicated by 14a in Figure 18 - and the surface 5b of the cylindrical housing. Thus, in the assembled condition, the elastic reaction of the element 15' pushes the body 10, as a whole, out of the housing (downwards, with reference to Figure 18), thus ensuring an elastic assembly and the recovery of possible tolerances between the parties involved.
[0095] As mentioned, the mounting configurations described with reference to Figures 16-19 can also be used when the level sensor 10 is associated with the top wall of the tank, in a manner similar to that shown in Figure 1.
[0096] As seen in the modalities mentioned so far, the level sensor 10 includes a set of capacitive elements, which include a unit electrode J1 - Jn ("n" being equal to 37, in the examples illustrated so far). In this case, the term "unitary" means that each electrode J belongs to a capacitive element that does not require an additional electrode, as typically occurs in known level capacitive sensors, which assume the presence of pairs of electrodes or front or interdigitation armatures , or the presence of a common electrode or armature, which a plurality of electrodes or armatures face. In other words, in the solution proposed here, each electrode J creates the armature of a type of "virtual capacitor", whose other armature is formed by the medium subjected to detection present in the tank and where the interposed wall of casing 16, or another insulating layer which replaces it, forms the dielectric or insulating material between the armatures of this virtual capacitor, to which the suitable dielectric or insulating material, constituted by the gel layer G described above, is possibly added.
[0097] In practice, therefore, each electrode J produces, together with the corresponding control electronics, a type of capacitive proximity sensor, capable of detecting the presence or absence of the medium, even without direct contact with the latter. This type of operation is based on the principle of detecting the electrical capacitance of a capacitor, electrode J being the sensitive side of the capacitor and forming an armature, while the possible presence, in the vicinity, of an electrically conductive medium creates the other armature of the capacitor. Thus, the presence or absence of a medium in the vicinity of each electrode J determines an electrical capacitance that the control electronics are capable of detecting.
[0098] In the application considered here, each J electrode is therefore capable of obtaining at least two different capacitive structures depending on the presence or absence of liquid in front of it, and precisely at least:
[0099] - a first capacitive structure, which has a first electrical capacitance value when an electrode J faces the liquid, or when the level of the liquid in the tank is equal to or greater than the electrode considered J, and
[00100] - a second capacitive structure, which has a second value of electrical capacitance when an electrode J does not face the liquid, or when the level of the liquid in the tank is below the considered electrode J.
[00101] In the preferred embodiment illustrated, as seen, the electrodes J are insulated from the liquid, so that they are contained in the electrically insulating and fluid-proof housing 16. The wall of the housing 16, which the electrodes J are facing, with the possible interposed gel layer G, can therefore be treated as a kind of dielectric material of the "virtual capacitor" mentioned above.
[00102] The thickness of the wall of the casing 16 that faces the electrodes J, or of the insulation layer, may be indicatively comprised between 0.1 and 5 mm, preferably between 0.6 and 1 mm, even more preferred, being about 0.8 mm. In addition, as already mentioned, the concave casing 16 can be replaced by a direct overmolding of the plastic material in the sensitive element or by a generic wall or insulating layer of electrodes J, with the thickness of the part facing electrodes J being analogous to the thickness indicated for the homologous wall of casing 16.
[00103] Each electrode J is electrically connected - alone or together and particularly in parallel with at least one other electrode J, as explained below - to a respective input of a plurality of controller inputs 24 belonging to circuit arrangement 23. Preferably, between each controller input and a corresponding electrode J, a filter resistor is provided (two of these resistors being indicated by R1 and Rn in Figures 6 and 7). The controller 24 is essentially arranged to discriminate the electrical capacitance value associated with each electrode J, at least between the aforementioned first and second electrical capacitance values and, consequently, to identify at least one liquid/air transition in the tank, indicative of the level of the middle when it is in a fluid state. In a preferred embodiment, the controller 24 performs a sequential sampling of the electrical capacitance values present in the inputs that are connected to electrodes J, in order to identify the aforementioned transition.
[00104] The controller 24 is preferably a digital electronic microcontroller provided with an analog-digital converter. By way of example, a commercial microcontroller suitable for the application proposed here has the identification code PIC16F1517, marketed by the company Microchip Technology Inc., Chandler, AZ, United States. It should be noted, however, that the functions of the controller 24 can be at least partially implemented via dedicated external circuits, for example, in a preferred embodiment, the controller 24 is composed of a microcontroller that implements an analog-converter module. digital, but in other embodiments, controller 24 may include a microcontroller (or a microprocessor or an ASIC or FPGA integrated circuit) and an integrated circuit (external or independent) dedicated to fulfilling the functions of the analog-to-digital converter.
[00105] Figure 20 shows, in schematic form, a controller 24, which, for example purposes only, includes "n" IN signal inputs (a total of twenty in this case), to which they are connected, through corresponding conductive rails 25, multiple J electrodes in a unitary configuration (ie not connected together or in parallel with other electrodes).
[00106] In a preferred mode, the detection of the electrical capacitance value at each of the IN inputs is performed in an indirect way, based on the voltage measurement. In such a case, preferably, the IN inputs of controller 24 are analogue inputs and the controller implements or has an associated analogue-digital converter.
[00107] In a preferred embodiment, a circuit, which includes a controllable switch and a capacitor, is associated with each IN input, here also defined as sampling switch and sampling capacitor. The controllable switch is switchable between a first position, in which the sampling capacitor is connected to a voltage source, and a second position, in which the same capacitor is connected to a respective J electrode or more J electrodes connected together (in parallel). Preferably, said voltage is a direct voltage, for example the supply voltage of the circuit arrangement 23. The controller 24 has means for causing the controllable switch to switch from the first position to the second position, so as to discharge the sampling capacitor in a manner proportional to the electrical capacitance value associated with electrode J or corresponding group of electrodes J connected together. In addition, controller 24 has means for determining the voltage at input IN when the controllable switch is in its second position, this voltage being indicative of the electrical capacitance associated with electrode J or group of electrodes J. Controller 24 also has means of comparison , to compare the given voltage present at the IN input with at least one corresponding reference limit, and thereby deduce whether or not the liquid is facing electrode J or at least one of the electrodes of the group of electrodes J connected together.
[00108] In a preferred mode, the scanning or sampling of the IN inputs is achieved using a sampling and hold circuit associated with an analog-digital converter, and measuring the capacitance of each J electrode or group of electrodes J occurs by comparing the measurement in relation to the intrinsic capacitance of this circuit.
[00109] An example of operation of a sensor according to the configuration in Figure 20 - that is, with individual electrodes connected to the respective controller inputs 24 - is shown schematically in Figure 21. Note that in this figure, for clarity , a top mounted level sensor is shown. In the configuration of Figure 1, the corresponding electrodes J are illustrated in the same order as in Figure 20 (therefore, with the smallest electrode J1 and the largest electrode Jn).
[00110] Tank 1 is visible in Figure 21, with the detection part 11 of the sensor being built-in or the J1-Jn electrodes being contained in the corresponding housing 16, which is at least partially immersed in the AdBlue liquid, indicated by L ( support 20 is not represented here for reasons of clarity or considering that, in a possible embodiment, the same casing 16 could fulfill the functions of support 20). In the illustrated example, the IN analog inputs of controller 24 are connected to an MTP multiplexer implanted in the controller itself, which essentially operates as an electronic split switch, which is associated with the sampling and holding circuit, comprising a holding capacitor CHOLD and an SS sampling switch. The SS switch is switchable between a first position, which connects to the VD voltage (eg the supply voltage of controller 24) and a second position, which connects to an output of the MTP multiplexer, or the connection position with the electrodes J.
[00111] By means of the MTP multiplexer, the IN inputs, and therefore the J electrodes, are sequentially connected to the SS switch. The SS switch is cyclically switched in a way synchronized with the operation of the MTP multiplexer, between the first position, charging the CHOLD capacitor, and the second position, connecting the same capacitor to the IN input currently selected by the MTP multiplexer and therefore , to the corresponding electrode J. With the switch SS in its second position, a charge balance is essentially determined between the capacitance of the capacitor CHOLD and the capacitance associated with the electrode J. In other words, with this balance of charges, the capacitor CHOLD is discharged in a manner proportional to the capacitance of the "virtual capacitor" defined by electrode J. By means of the ADC analog-digital converter, the amount of charge or a residual voltage of the CHOLD capacitor is then determined, which is then compared with a threshold of predefined reference, in order to deduce whether electrode J is facing liquid L or not, or if electrode J has assumed the first capacitive structure or configuration. the or the previously indicated second capacitive structure or configuration.
[00112] As explained above, when an electrode J is facing liquid L (for example, electrode J1 in Figure 21), a first electrical capacitance value is associated with it, while otherwise (as with electrode Jn or Jn-1 of Figure 21), a second electrical capacitance value is associated with it, which is less than the first value. In Figure 21, the block of dotted lines, indicated by VE, is intended to represent, in a schematic way, the functionality of the "virtual" electrode or armature produced by liquid L, as explained above.
[00113] Following the aforementioned balance between the loads of the CHOLD capacitor and the J1 electrode, the voltage value at the capacitor heads and/or IN1 input may essentially coincide or may be greater or less than a given threshold reference, stored from beforehand in controller 24. For example, in one mode, controller 24 can be programmed so that the detection at an IN input of a voltage equal to or above the preset limit is indicative of the fact that the considered electrode does not face the liquid L (as in the case of electrode Jn), while the detection at input IN of a voltage below the threshold is indicative of the fact that the electrode is facing the liquid (as in the case of electrode J1).
[00114] As is evident, by performing the sequential sampling described, the controller 24 is able to locate the two electrodes J corresponding to the liquid/air transition in tank 1. And as soon as the presence of the liquid/air transition is detected, the controller can deduce the liquid level based on the fact that one of the two electrodes J, which is associated with a voltage value equal to or above the threshold, ends up being the first one in the air (or on the other hand, the electrode that is associated with the stress value below the threshold ends up being the last that faces the fluid).
[00115] For this purpose, information representative of the values in length (height) corresponding to the position of each electrode J are preferably contained in circuit 24, or in any case, the distance between electrodes J in the direction of the geometric axis of measurement X, in order to establish or calculate the level according to the predefined measurement unit. The electronics of the sensor 10 provide for the transmission or generation of signals out and/or towards the electrical connector of the sensor 10, representative of the level information.
[00116] It will be understood that the functionality described with reference to Figure 21 can also be obtained with different circuits, however, technically equivalent to the one exemplified. For example, a respective circuit could be associated with each IN input of controller 24, which performs the functionality of the sampling and holding circuit described above, with an MTP multiplexer between these circuits and the ADC converter. Another possibility is to equip each IN input with a circuit that performs the features of the sampling and retention circuit described above, directly connected to an ADC converter, such a case is shown schematically, for example, in Figure 22.
[00117] Preferably, the sensor electronics, subject of the invention, are properly initialized and/or calibrated during production, with the storage of the relevant software or program and/or at least part of its variants (such as a or more limits used in level detection), for example, which depends on the physical configuration of the sensor and the installation system, being represented here by tank 1.
[00118] In one modality, the calibration step includes a reading of all values of the J electrodes in unprocessed condition or in air (i.e., not facing the liquid), for the purpose of defining the first reference limits and /or an initial deviation cancellation, or to compensate for parasitic capacitances arising from materials, structures, thicknesses, etc. sensor and/or installation system. This value is stored as a threshold reference for the detections, such as a maximum threshold on the electrical voltage detectable by the CHOLD capacitor and/or the ADC circuit, this threshold value can subsequently be varied as a consequence of measurements made over the lifetime of the sensor, for example, via a dedicated reference electrode. This calibration operation is preferably performed only once on the production line, but for some applications where the tank has a critical geometry, which can be heavy when measuring the raw data from the J electrodes (such as very narrow volumes and the presence of metallic material), it is possible to use this calibration or the self-calibration directly on the installed sensor 10, in order to obtain an ideal calibration in the current system and/or to cancel all possible noise effects arising from the external environment.
[00119] The operating principle described here is to some extent dependent on the temperature and wear of the system, if observed in an absolute way. For that reason, in a preferred embodiment, the controller 24 is programmed to perform a measurement of a differential type, preferably to employ at least one reference electrode for that purpose. Because the effect of temperature is represented by a deviation in the measurement of the voltage value determined at an IN input of the controller 24, to perform the differential measurement between a detection electrode and a reference electrode, it is possible to obtain both the measurement over the detection electrode as the subtraction of the common mode effect present in the detection electrodes, and then canceling any thermal and/or structural deviation produced by the temperature change and/or wear; the thermal deviation mentioned above can also be compensated by means of a temperature sensor, for example, of the kind indicated by 26 and 27. According to this modality, therefore, the determined voltage value, used for the comparison with at least a reference limit, is preferably a differential value.
[00120] The aforementioned reference electrode is preferably the smallest electrode within tank 1 and therefore, with reference to the examples illustrated so far, electrode J1. It is also possible to provide up to more reference electrodes (for example, the first three J electrodes starting from the bottom), usable for performing the differential measurement, as well as for programming the controller 24 to choose, on its own, any of the J1 electrodes. -Jn as the reference electrode for the purpose of performing differential measurement. The controller 24 being, in fact, able to identify an electrode that faces or does not face the liquid, because the electrical capacitance is different in the two conditions and because of the presence of the upper limit mentioned above.
[00121] In such a mode, the controller 24 performs a scan of all electrodes J with the acquisition of the corresponding raw voltage data, to verify the presence of the liquid. In this step, the controller 24 calculates the difference between the raw data from each detection electrode and the raw data from the reference electrode J1, thus obtaining a relative measure. This difference is compared to at least a minimum threshold defined at the design stage. In a possible modality, if at least one of the calculated differences between each detection electrode J2 - Jn and the reference electrode J1 is below the minimum limit, then this means that the detection electrode in question is at least partially facing the liquid L ; in the opposite case, the electrode in question is in the air or at a height above the liquid level L.
[00122] As already indicated, the level investigation is essentially based on the identification, carried out by the controller 24, of the two detection electrodes corresponding to the transition between liquid and air. The evaluation is performed by comparing the relative information (differential measurement) with the predefined limits for each electrode in the design stage (possibly replaceable by the defined and stored limits that follow the liquid test in the production stage), in order to deduct whether an electrode faces the liquid or not. After the scan is performed, the controller can identify two adjacent sensing electrodes, one of which is facing the liquid and the other is not, ie the position (height) of the liquid/air transition in tank 1.
[00123] In an inventive modality in itself, the electronic circuit of the sensor 10 is subjected to calibration or configuration according to the type and/or conductivity of the medium subjected to level detection, especially considering that in the case of less conductive means, or resistive means, a type of electrical resistance virtually connected in series to the measurement capacitor would be determined, which resistance could determine an increase in the time needed to reach the final limit value (such as an increase in the charging time of the " virtual capacitor" to which an electrode J belongs and/or an increase in the discharge time of the CHOLD capacitor). In this context, the calibration mentioned above can be, for example, designed to take into account any delay in sample measurement and to avoid false readings of values that are not yet well stabilized.
[00124] In an inventive mode by itself, the electronic circuit of the sensor 10 is configured to detect the charge curve of the "virtual capacitor" corresponding to the measurement electrode J and/or to detect the discharge curve of the sampling capacitor , such as the CHOLD capacitor, where the charge and/or discharge curve is variable at least in proportion to the conductivity and/or electrical impedance characteristics of the medium under measurement, in order to be able to determine the characteristics of the medium under detection. The electronic circuit can employ the information thus obtained for the purpose of performing one or more detection operations, processing operations, comparison operations, storage operations, compensation operations and signaling operations. To that end, structural and/or circuit elements are usable which are at least partially analogous to those previously described.
[00125] As mentioned in a particularly advantageous modality, the detection electrodes comprise at least first detection electrodes, connected to the respective IN inputs of the controller 24, and second detection electrodes, which are electrically connected together or in parallel to the first sensing electrodes, the definition of parallel connection also referring to the parallel connection between the "virtual capacitors" defined by the electrodes J, which are mutually connected together with respect to a respective IN input.
[00126] An example of this type is illustrated schematically in Figure 23, where the aforementioned first electrodes go from electrode J4 to electrode J20, while the second electrodes go from electrode J21 to electrode Jn. In this example, electrodes J1 - J3 can be reference electrodes. In the configuration of Figure 23, a first subset (or module, block or group) of first electrodes can essentially be identified, which runs from electrode J4 to electrode J20, and a second subset of second electrodes, which runs from electrode J21 to the Jn electrode, which are essentially connected together or in parallel. The number of electrode subsets can be increased to obtain shorter or longer level sensors or to allow for different level measurements.
[00127] In such a modality, the comparison means implemented in the controller 24 are arranged to compare the voltage determined at the IN input corresponding to two electrodes connected together (for example, electrodes J4 and J21 in parallel) with at least two corresponding reference limits, in order to deduce whether or not the liquid is facing the first sensing electrode (the J4 electrode) and/or the second corresponding sensing electrode (the J21 electrode). The measurement can be performed as described previously. Preferably, in this case too, the measurement is performed by obtaining the raw data at the IN input to which the two detection electrodes are connected together and then by referencing this value with respect to an electrode of reference, that is, to electrode J1 in order to move from an absolute measurement to a differential measurement and cancel any common mode error effect due to temperature and/or wear of the level sensor, as previously described.
[00128] In one modality, the value obtained by the differential measurement is compared with a number of limits equal to the number of electrodes connected together, increased by 1. With reference to the example considered here of two J electrodes in parallel, therefore, the value differential is compared with three distinct limits defined at the design or production stage: a value equal to a first limit or within a certain range (eg +/- 40%) indicates that both electrodes are not facing the liquid, a value equal to a second threshold or within a certain range (eg +/- 40%) indicates that one of the electrodes (identified according to its physical location) faces the liquid and the other electrode does not ultimately a value equal to a third threshold or within a certain range (eg +/40%) indicates that both electrodes are facing the fluid.
[00129] In a different modality, a more simplified analytical logic is provided, according to which the value obtained by the differential measurement is compared with a number of limits equal to the number of electrodes connected together. Again with reference to the example considered here of two J electrodes in parallel, the differential value is compared with only two limits: a value above a first limit indicates that both electrodes are not facing the liquid, a value between the two limits indicates that one of the electrodes (identified according to its physical location) faces the liquid and the other electrode does not, a value below the second threshold ultimately indicates that both electrodes are facing the fluid.
[00130] Obviously, according to the same principle described above, more than two electrodes connected together can be provided, or more subsets with the respective electrodes in parallel, in which case the number of reference limits for each IN input will be equal to the number of electrodes in each parallel increased by 1, or equal to the number of electrodes in each parallel, depending on the analytical approach implemented.
[00131] For example, in Figure 24, the case of the first, second and third sensing electrodes connected together or in parallel is illustrated. The first electrodes go from electrode J4 to electrode J20, the second electrodes go from electrode J21 to electrode J37 and the third electrodes go from electrode J38 to electrode Jn. In this example, electrodes J1 - J3 can be reference electrodes. Therefore, in the example in Figure 24, it is possible to identify three subsets of electrodes or "virtual capacitors", with the electrodes of one subset (J4-J20) being essentially connected together or in parallel with homologous electrodes of the other subsets (J21-J37 and J38-Jn).
[00132] In such a modality, the comparison means implemented in the controller 24 are arranged to compare a given voltage at the IN input corresponding to three electrodes in parallel (for example, electrodes J4, J21 and J37) with three reference limits corresponding, in order to deduce whether or not the liquid is facing the first detection electrode (the J4 electrode) and/or the corresponding second detection electrode (the J21 electrode) and/or the third detection electrode (the J37 electrode) . An operating example of an arrangement of the type illustrated in Figure 24 is described below with reference to Figures 25 and 26.
[00133] Figure 25 is a schematic representation similar to that of Figure 21, in which only two inputs IN4 and IN of controller 24 are highlighted (the representation of reference electrode J1 has been omitted here for clarity). As in the case of Figure 21, controller 24 performs sequential sampling of its analog IN inputs, with corresponding differential measurement for each of them and corresponding comparison with the three predefined limits for the J electrodes that face the liquid L and/or with the pre-set limit for "dry" J electrodes, that is, electrodes that do not face liquid L.
[00134] The measurement principle adopted for the various IN inputs, for example, the IN4 input, is exemplified schematically and graphically in Figure 26. It can be assumed that the initial voltage of 5 V, indicated in the graphics, corresponds to the voltage VD in Figure 25. TH1, TH2 and TH3 indicate three predefined threshold values for input IN4, or a high limit, a low limit and an intermediate limit, respectively, for the condition of electrodes facing the liquid.
[00135] The graph in part a) of Figure 26 shows the condition that occurs in the case where none of the three electrodes J4, J21 and J38 is facing the fluid, following the switching of the SS switch in Figure 25 in the position where the CHOLD capacitor it is connected to the corresponding sensing electrode group J4, J21 and J38. In the figure, the decreasing voltage limit is intended to represent the decrease in the voltage value due to the differential measurement performed, in the modalities previously described, and/or the fact that, even if they are not facing liquid L, an electrical capacitance minimum is in any way associated with the three electrodes in question, depending on the structure of the device. The drop in voltage illustrated in the graph in part a) of Figure 26 is also detected in reference to a certain "dry" threshold value, indicated by THD, greater than the maximum threshold TH3 value, this threshold THD value also being usable for the purpose of discriminating against the three detection limits TH1, TH2 and TH3. The drop in voltage illustrated in graph a) remains within a certain proximity (eg the aforementioned value of +/40%) of the THD limit and in any case above the TH3 maximum limit. Therefore, controller 24 deduces the absence of liquid in front of electrodes J4, J21 and J38.
[00136] The graph in part b) of Figure 26 shows the condition in which one of the electrodes J4, J21 and J38 is facing the liquid L. In this case, the decrease in the voltage value is greater than in the previous case. In addition to the differential measurement, in fact, the total electrical capacitance associated with the three electrodes is greater than in the previous case, since one of them is facing liquid L. The voltage value is, in this case, within the determined proximity of the limit TH3 and from this, the controller 24 deduces the presence of liquid in front of only one of the electrodes, that is, the smallest electrode of the three (the physical position of the electrodes being known by the controller).
[00137] The graph in part c) of Figure 26 shows the condition corresponding to that of Figure 25 or the condition in which two of the electrodes J4, J21 and J38 are facing the liquid L. The voltage decrease is now greater than in the case of part b) of Figure 26 because, in addition to the differential measurement and in the condition in question, the total electrical capacitance associated with the three electrodes is also greater compared to the previous case. The voltage value is now within a certain proximity of the threshold TH2 and the controller 24 therefore deduces the presence of liquid in front of electrodes J20 and J37 and the absence of liquid in front of the remaining electrode Jn, that is, the largest electrode of the three. This discrimination is also performed considering that, in the case of freezing conditions or partial solidification of the liquid, it is possible to combine other measurements in order to better discriminate this condition, such as checking and comparing with the state of adjacent electrodes and/ or temperature detection. Finally, the graph in part d) of Figure 26 shows the condition in which all three electrodes J4, J21 and J38 are facing liquid L. The voltage drop is evidently greater than in the case of part c) of Figure 26 because, in addition to the differential measurement and in the condition in question, the total electrical capacitance associated with the three electrodes is at its maximum value. The voltage value is now within the determined proximity of the TH1 threshold, from which the controller 24 deduces the presence of liquid in front of the three electrodes J4, J21 and J38.
[00138] As explained above, the same results are achievable using a simplified logic, that is, comparing the voltage value with the three detection limits TH1, TH2 and TH3 alone, as follows:
[00139] - part a) of Figure 26: with the voltage value that remains above the TH3 limit, the controller 24 deduces the absence of liquid in front of electrodes J4, J21 and J38;
[00140] - part b) of Figure 26: with the voltage value that is between the TH3 limit and the TH2 limit, the controller 24 deduces the presence of liquid in front of the smallest electrode of the three;
[00141] - part c) of Figure 26: with the voltage value that is between the TH2 limit and the TH1 limit, the controller 24 deduces the presence of liquid in front of electrodes J20 and J37 and the absence of liquid in front of the electrode remnant Jn; and
[00142] - part d) of Figure 26: with the voltage value that increases below the TH1 threshold, the controller 24 deduces the presence of liquid in front of the three electrodes J4, J21 and J38.
[00143] By scanning the IN inputs using one of the modes exemplified above, the controller 24 is able to identify the liquid/air transition. In the specific case of Figure 25, therefore, the controller 24 can deduce the presence of the liquid/air transition between electrodes J37 and J38, thereby identifying the liquid level in tank 1.
[00144] From the description above, it becomes evident how the type of solution proposed is extremely flexible in relation to the possible lengths needed for the level sensor. In other words, with a given controller 24 and with the same number of analog IN inputs (or with a slightly larger number of IN inputs, as described here later) it is possible to produce level sensors with different lengths through the use of electrodes individual J for detection of either two J electrodes in parallel, or even three J electrodes in parallel and so on.
[00145] For example, by placing twenty individual J electrodes 2 mm high, at a distance of 2 mm from each other, an area of 78 mm is obtained, which is sensitive to level measurement ((20 electrodes + 19 spaces between them) 2 mm). When it is necessary to increase the length of the sensitive area (measurement of higher levels), keeping the same measurement resolution, it is possible to use two electrodes in parallel, or three and still keep the same controller 24.
[00146] Preferably, in the presence of the first sensing electrodes connected together with additional sensing electrodes, it is preferable that the physical locations of the various subsets of electrodes are farther apart from each other, so as to increase the signal difference and consequently, the quality of level information. For this reason, in a preferred embodiment, if a variety of groups of detection electrodes connected together are provided, the electrodes of each group will form respective subsets arranged in sequence along the geometric detection axis of the sensor, as becomes apparent , for example, in Figures 23 and 24. In general and with reference to, for example, Figure 24, a rule can be applied, in which a given number y (eg 17 electrodes) of first electrodes (J4-J20) in parallel with the second electrodes (J21 -J37), between each first electrode and the corresponding second electrode, y-1 electrodes will be interposed (eg 16 electrodes).
[00147] Thanks to the constructive typology described, it is also possible to have different sensitivities for the level readings. This can be achieved, in the production stage of the part 20a of the corresponding electrode holder J, by placing the electrodes themselves at a center-to-center distance equal to the desired resolution. It is also possible to provide at least two different measurement resolutions on the sensitive portion 20b of the sensor, particularly at least a higher measurement resolution and a lower measurement resolution, in a low area and in a high area of the portion 20b or vice versa. versa. In this case, the electrodes in the lower area of portion 20b will be closer to each other than the electrodes present in the upper area or vice versa. The minimum distance between two electrodes can be, for example, equal to 1 mm. Therefore, it becomes evident that the dimensions of the electrodes define the amount of electrical capacitance measurable by the control electronics, so that an electrode of greater magnitude would thus provide a greater dynamics or value.
[00148] The J electrodes are preferably (but not necessarily) equal to each other and can be, for example, produced with dimensions of 20 mm (length) x 2 mm (height) and accommodated at a distance of 2 mm from each other ; for sensors with a level lower than 100 or if it is necessary to increase the resolution in an area of the sensitive portion of the sensor, it is possible to reduce the size of the electrodes and, therefore, also reduce the distance between them, in order to obtain a higher resolution of measurement. In these cases, the electrodes can have, for example, dimensions of 15 mm (length) x 1 mm (height) and can be accommodated with 1 mm of distance between them. To maximize the measurement dynamics corresponding to the liquid, for example, in relation to the AdBlue liquid considered here (or another solution with urea or another reducing agent), it is also preferable to size the electrodes, to any value of their length, so that the height of one electrode is equal to the distance between two adjacent electrodes.
[00149] Figures 27 and 28 represent, with views similar to that of Figure 24, other possible arrangements, which include three groups of J electrodes in parallel. In the case of Figure 27, the two illustrated terminal electrodes of the set or electrodes J1 and Jn are not connected in parallel with the other electrodes and constitute reference electrodes, respectively, for the condition of presence and absence of liquid or vice versa, which function is preferably programmable or predetermined, for example, so as to allow mounting of the sensor 10 in tank 1 under the two conditions of Figures 1 and 2.
[00150] Figure 27 illustrates the configuration, in part similar to that of Figure 24, where the set of electrodes includes three subsets of the first, second and third sensing electrodes connected together (in parallel) to each other, the subsets being, in the however, separate from the individual electrodes. The first electrodes go from electrode J2 to electrode J17, the second electrodes go from electrode J19 to electrode J34 and the third electrodes go from electrode J36 to electrode J51. In this example, the intermediate electrodes J18 and J35 are independent and are interposed between the aforementioned three electrode subsets. In particular, the unit electrode J18 is interposed between the first subset (J2-J17) and the second subset (J19-J34), while the unit electrode J35 is interposed between said second subset and the third subset (J36-J51).
[00151] Intermediate electrodes J18 and J35 allow a clearer distinction between subsets of electrodes connected together, in particular, in order to detect particular conditions or states of the liquid or other medium subjected to detection (such as a solidification state or partial freezing of the liquid or the medium), particularly, a more precise and/or clear distinction when detecting the transitions of "liquid - air or gas" and/or "liquid - air or gas - solid or ice ". To this end, it is considered that the interposed electrodes J18 and J35 allow a faster determination of which and/or how various subsets or parts of them are facing the medium (or are not facing), and can then identify more quickly , areas of uncertainty in which more accurate measurements can be performed or in which detection of the transition zone between two adjacent electrodes can be done, for example, for detection of the "liquid to air" transition zone, as previously indicated .
[00152] The presence of independent intermediate electrodes is also useful to improve the discrimination of values in relation to the reference limits mentioned above (such as the TH1, TH2, TH3 and/or the "dry" limits), in particular, in the case of a high number of electrode subsets together (in parallel). In case of several subsets, in fact, several reference limits will be present, which are closer to each other; for example, where it is preferable, for cost reasons, to use a lower resolution ADC analogue-digital converter (eg 8 bits instead of 10 or 12 bits); the presence of said independent electrode J18, J35 allows a clearer and/or more determined detection, in a manner analogous to that described in reference to graph b) of Figure 26, where only the TH3 limit is considered.
[00153] Figure 28 is essentially similar to Figure 27, distinguished by the fact that the intermediate electrodes J18 and J35 are not individual, but parallel to each other and connected to the same IN input. Such a configuration can be useful to limit the number of connections with the intermediate electrodes provided, while ensuring a good distinction of the two limits (such as the TH1 and TH2 limits) associated with the same IN input.
[00154] With reference to the exemplary configurations described in Figures 27 and 28 and considering a greater number of subsets or groups of electrodes connected together (for example, equal to or greater than five subsets), more intermediate electrodes can then be provided, individually connected or joined in parallel pairs.
[00155] Figure 29 illustrates some of the circuit components used in a possible practical embodiment of the invention. Part a) of the Figure shows the microcontroller 24 used, in this case the microcontroller mentioned above PIC16F1517 from the company Microchip Technology Inc, with indications of their corresponding inputs and outputs. Part b) of the Figure shows electrodes J, which, in this case, comprises electrodes J1-J17 connected in a unitary configuration to the respective inputs of microcontroller 24, as well as electrodes J18 - J27 connected to the respective inputs of microcontroller 24 together or in parallel with electrode J28 - J37. It is worth noting, regarding the connection between each of the J1-J27 electrodes and the corresponding input of the microcontroller 24, the filter resistance mentioned above, which can possibly be omitted. Part c) of Figure 29 illustrates a possible circuit diagram of a temperature sensor usable in the device according to the invention, such as, for example, temperature sensor 26 and/or 27 of Figure 7, while part d ) of the Figure illustrates a possible communication port or electrical connector that belongs to the circuit arrangement 23 of Figure 7, usable, for example, to program and/or calibrate the level sensor in the production stage. Obviously the circuit arrangement 23 also includes a power supply stage, not shown, as it is producible according to techniques known per se.
[00156] Due to its nature of having distinct detection elements, the sensor, according to the invention, is capable of performing level measurements in a wide range of situations, which occur, for example, in SCR systems. A first typical situation previously described is that in which the liquid contained in the tank is entirely in a fluid state. A second situation is where the tank is operated under conditions of low temperature, such as to produce total freezing of the liquid present in the tank. Also in this case, the sensor 10 is perfectly capable of recognizing the electrodes facing the frozen mass and thereby calculating its height. A third situation is where the tank contains a predominantly liquid part, in which frozen parts float or are immersed ("iceberg effect"). Also in this case, the level measurement made by the sensor 10 can take place in the modalities already described above, since the presence of frozen parts does not affect the operation of the sensor 10 or the level calculation. Similar considerations apply when there is a direct transition between liquid and ice.
[00157] Sensor 10 is also capable of performing detections in mixed situations when the liquid-ice system is freezing or thaw. A case of this type is illustrated schematically in Figure 30, where at the top of the tank 1 there is frozen liquid, indicated by I, to form a partial or total "cap"; in the lower part of tank 1, at a higher temperature, the content L of the tank is already in liquid form and between the solid part I and the liquid part L, there is air, indicated by A, or a vacuum. This condition can arise, for example, in the case of using liquid L contained in the tank before it has completely frozen over or after it has partially defrosted the contents of the tank by means of a heater. In this case, an intermediate or air gap between the liquid and the ice essentially corresponds to the part of the liquid used. According to one aspect of the invention, in such a condition, it is advantageous to detect the level of the liquid in order to avoid its total use, that is, in order to leave at least a part of the liquid in the tank, for reasons that will be explained later.
[00158] In the condition of the exemplified type, the control electronics of the sensor 10 are able to correctly identify the presence of one or more electrodes (J4, J20) that face the liquid L, followed by the presence of one or more electrodes (J21 , J37) that face the air A, followed, in turn, by one or more electrodes (J38, Jn0) that face the ice. Advantageously, in such a situation, the sensor control electronics according to the invention are able to define both the amount/level of the liquid content L, important because it is the part directly usable at the moment by the SCR system, as the total amount of liquid (L+I) present in the tank, important for tank refill planning 1. A possible control logic, which is usable for the detection of the so-called "igloo effect" (presence of a layer of air covered by a layer of ice) may be as follows:
[00159] - only all detection electrodes that are "dry", that is, facing the air, are considered;
[00160] - the information obtained about a number (for example, 3) of successive electrodes to an electrode considered dry are evaluated (successive electrodes meaning those above the electrode considered dry, in the case of mounting the sensor from the underside or below of the electrode considered dry, in the case of mounting the sensor from above);
[00161] - check if above a "dry" electrode there is an electrode - between the aforementioned successive electrodes - which is facing the liquid; for this purpose, in a preferred modality, the difference can be calculated between the measurements performed on said successive electrodes and the electrode considered "dry", comparing the three individual results with the absolute limits defined in the design stage. If at least one of these differences coincides or is within the determined proximity of the defined threshold, the presence of the "igloo effect" will be determined.
[00162] It is also possible that, starting with the situation of the type shown in Figure 30, a refill of the tank is performed, thereby introducing a part of the liquid L, which could be blocked by the ice cap I still present in tank 1 According to the principles set out above, also in this case, the sensor according to the invention is clearly capable of detecting the increase in the total level of liquid present in tank 1. Again with reference to situations of the type represented in Figure 30, it will be It is understood that, if necessary, the electronics of the sensor 10 can be programmed to perform subsequent detections, spaced apart for a certain period of time (e.g., 2 minutes), in order to verify the progressive melting course of the ice cap I.
[00163] As already indicated, the sensor electronics, subject of the invention, are initialized and calibrated during the production stage, with the storage of the software and the corresponding variables, which includes one or more of the physics-dependent reference limits sensor configuration - tank system, whose minimum limits are representative of the condition of an electrode or group of electrodes that does not face the fluid. The lower limit for the opposite case (liquid that faces an electrode) can be preset through experimentation and/or possibly set through another test with the sensitive part 11 of the sensor completely immersed in the liquid. In the case where the sensor 10 provides electrodes in parallel, the intermediate limits are also defined including experimentally the minimum limit and the maximum limit.
[00164] Temperature information can be obtained through sensor 27 and/or 26 and can be used by electronics 23 to recognize the system tank situation, for example, to deduce the liquid freezing condition and activate a heater corresponding, and/or to mathematically compensate the information about the level measurement, particularly in the case of applications at critical temperatures, where the use of the differential measurement with the reference electrode may not be sufficient to guarantee the error compensation.
[00165] It should be noted that, in order to cause the melting, by means of a heater, of some frozen liquids, such as the AdBlue additive considered here, in any case it is necessary for a part of the molten liquid to be present in the tank, so that the heater can continue heating the liquid and transmitting heat to the frozen mass. When applying to an SCR system, when the vehicle engine is started, there is an additive removal and this is not particularly problematic, as long as a certain amount of the heated additive still remains in the tank, which additive can reach the frozen mass by virtue of vehicle movement and consequent agitation of the hot liquid in tank 1. If, on the other hand, the initial removal of the additive determines the emptying of all residual liquid from the contents of the tank, the melting effect will be stopped. For this reason, in a preferred embodiment, the sensor according to the invention can be arranged, for example, at the software level, to detect the level of the molten liquid, so as to guarantee the presence of a minimum level, sufficient for the melting effect is not interrupted; to that end, the sensor 10 can send a suitable signal or data, for example usable by the vehicle electronics and/or for relevant alerts.
[00166] It will be understood, of course, that with the sensor, subject of the invention, the progressive melting of the frozen mass of liquid is also easily detectable, as the melting gradually progresses. The sensor 10 is, of course, capable of operating during heating and/or defrosting of liquid or other medium subjected to level detection, as well as in the course of its possible freezing.
[00167] The sensor 10 is interconnected with an external control system, such as an SCR system control unit, through connector 12b. To this end, the sensor control electronics 23 are arranged for data transmission, preferably in a serial format, more preferably via an interface and/or a SENT (Single Edge Nibble) protocol Transmission). The signals sent may also comprise, in addition to information representative of the level of the medium subjected to detection, information representative of at least one of the temperature of the medium or air present in the tank, the presence of the freezing or solidification condition of at least part of the medium subjected to detection, the presence of an abnormal function condition, a warning signal and/or status.
[00168] From the above description, one arrives at the deduction of how the operation of the level sensor described here is essentially independent of the dielectric constant of the medium being measured. The sensitive element represented by the set of electrodes is capable of carrying out the level measurement even if it is completely isolated from the liquid, thus ensuring its protection against contact with aggressive liquids, such as AdBlue or urea, and providing good robustness mechanics for the sensor structure. With this fact in perspective, the wall thickness of the casing 16, in particular, in the area facing the electrodes J, may be indicatively comprised between 0.1 and 5 mm, preferably between 0.6 and 1 mm, of even more preferably, about 0.8 mm; as already mentioned, the casing can be replaced by direct overmolding of the plastic material on the sensitive element, or by a generic insulating wall of the electrodes J, with a thickness similar to that indicated.
[00169] The sensor described here can be of any length and therefore it is easily adaptable to any reservoir. A problem present in the application of level sensors is exactly that represented by the length of the sensor or the height of the level to be measured, which is a variable that depends on the tank installation. In this context, the invention allows:
[00170] - the use of standardized electronics or a minimum possible number of components, with a microcontroller that, for the same or nearly the same number of inputs, can manage a large series of lengths due to the possible connection together or in parallel of multiples electrode subsets;
[00171] - the use of a highly flexible circuit model for the various possible lengths required for the sensor or to keep the same microcontroller with the same number of inputs even for level sensors with different lengths. As already mentioned, for example, by arranging 20 electrodes 2 mm high at a distance of 2 mm from each other, a sensitive area of 78 mm for measuring length is obtained, or 78 mm of a sensitive area for a group of first electrodes; when it is necessary to increase the length of the sensitive area, it is possible to use the same number of inputs by provision of second electrodes in parallel to the first, thus being possible to keep the same microcontroller, both for reasons of course and in terms of design. As a non-limiting example, it is theoretically possible to reach lengths close to 780 mm, with ten subsets of electrodes. For such long lengths, it is also possible to reduce the number of electrode subsets, in the case where a lower measurement sensitivity or resolution is acceptable, at least in certain parts or levels of the sensor. To this end, as already mentioned, it is possible, for example, to increase the distance between the electrodes in areas where the measurement accuracy is less significant (such as a level close to the full tank) or, conversely, to decrease this distance with the intention to have a higher resolution in the areas considered most critical (for example, close to the minimum level of the tank).
[00172] In several previously described modalities, the mounting of the sensor 10 on the bottom wall of the tank was considered so that the electrode indicated by J1 would represent the smallest electrode inside the tank itself. Obviously, as explained, sensor mounting can also take place on the top wall of the tank, in which case - with reference to the illustrated examples - electrode J1 will be the one near the distal end of portion 20b of bracket 20 and electrode Jn will be the one near the proximal end of said portion 20b. Obviously, the control software will be arranged to allow level detection according to the sensor installation point, as another advantage of the flexibility of use.
[00173] From the above description, the characteristics of the present invention become clear, as well as its advantages, represented mainly by the simplicity of production of the proposed level sensor due to its low cost, its precision and reliability, and the its high flexibility of use and configuration.
[00174] It will be apparent to a person skilled in the art that numerous variants are possible for the devices and methods described as an example, without departing from the scope of the invention as defined by the appended claims.
[00175] According to possible variants of modalities or applications, the level sensor, subject of the invention, can be arranged outside the reservoir or the tank that contains the medium subjected to detection (i.e., on an external wall or on a formed base on this outer wall of the reservoir or tank), with the set of electrodes J resting against a wall of this reservoir, with the possible interposition of gel G or similar. In this case, the aforementioned reservoir wall is properly configured in terms of material and thickness, in order to create the layer that electrically insulates the electrodes J from the inner side of the reservoir 1. A possible modality is illustrated in Figure 31, in which the housing of the sensor body 10a is, in this case, an open-side housing 16', so that the front part of the support portion 20b and therefore the electrodes J are facing and/or supported against a respective portion 16 "of a side wall 6 of tank 1; in the example, this portion 16", which, in this case, creates the insulating layer that electrically insulates the electrodes J from the inner side of tank 1, is narrowed from the rest of the wall 6, for example, with a thickness between the aforementioned values 0.1 and 5 mm.
[00176] According to other variants of modality, the casing 16 and at least part of the corresponding features previously described can be included in at least one part integrated or associated with the reservoir or tank. As already mentioned, the electrodes could be directly associated with a wall or portion of the tank wall (for example, the 16" portion of Figure 31), which in this case would constitute both the substrate for the J electrodes and the layer of insulation from the tank contents.
[00177] The present invention has been described with particular reference to detecting the level of a liquid medium, particularly a urea-based additive, but as already mentioned, the described sensor can also be used in combination with different substances and materials, and it can also potentially be subjected to solidification for reasons other than freezing (eg a mass of a powdered material or the like, in which a part is compacted or solidified, for example due to excessive moisture).

权利要求:
Claims (19)
[0001]
1. Level sensor for detecting the level of a medium contained in a reservoir (1), the sensor (10) comprising: a set of capacitive elements designed to be associated with the reservoir (1), in particular, to extend accordingly with a geometric detection axis (X) of the middle level (L), the set of capacitive elements comprising a plurality of electrodes (J1-Jn), in particular, on a face of an electrically insulating substrate (20) having a generally elongated shape, the electrodes (J1-Jn) being spaced apart from each other, in particular along the geometric detection axis (X) and being essentially coplanar with each other; at least one insulating layer (16; 16") for electrically isolate the electrodes (J1-Jn) from the inner side of the reservoir (1), a controller (24) that has a plurality of inputs (IN1-INn), in which each capacitive element comprises a group of electrodes connected in common each other (J4, J21, J38; J20, J37, J n), particularly in parallel, the electrode group (J4, J21, J38; J20, J37, Jn) being connected to a respective input (IN) of the plurality of inputs (IN1-INn), where the controller (24) is preconceived to discriminate an electrical capacitance value associated with each electrode (J1- Jn) to deduce the level of the medium (L) present in the reservoir (1), in which the electrodes of the respective groups form, on the insulating substrate (20), respective subsets of electrodes (J4-J20; J21-J37; J38- Jn) arranged in a sequence along a geometric detection axis (X), characterized by the fact that a given number y of first electrodes (J4-J20) connected in parallel to the second electrodes (J21-J37) between each first electrode and the corresponding second electrode, y-1 electrodes are interposed.
[0002]
2. Level sensor according to claim 1, characterized in that each capacitive element consists of a group of electrodes connected in common to each other (J4, J21, J38; J20, J37, Jn), particularly in parallel , so that each group of electrodes composes an armature of a virtual capacitor, whose other armature is created by the medium contained in the reservoir and in which the insulating layer (16; 16") makes up the dielectric material between the armatures of the aforementioned virtual capacitor , and in which the controller (24) was preconceived to perform a sequential sampling of the electrical capacitance values present in the inputs (IN1-IN) and thus discriminating an electrical capacitance value associated with each electrode for the deduction of the level of the medium (L) present in the reservoir (1).
[0003]
3. Level sensor according to claim 1, characterized in that each electrode (J1-Jn) is capable of reaching at least: - a first configuration or capacitive structure that has a first electrical capacitance value when the electrode (J1-Jn) faces the medium (L), or when the level of the medium (L) in the reservoir (1) is equal to or greater than the electrode (J1-Jn), and - a second configuration or capacitive structure that has a second value of electrical capacitance when the electrode (J1-Jn) does not face the medium (L), or when the level of the medium (L) in the reservoir (1) is below the electrode (J1-Jn).
[0004]
4. Level sensor, according to claim 1, characterized in that the controller (24) is preconceived to discriminate the electrical capacitance value associated with each electrode (J1-Jn) from at least a first and a second value of electrical capacitance, to identify a transition between the medium and the air or gas in the reservoir (1), which represents the level of the medium (L).
[0005]
5. Level sensor according to claim 1, characterized in that with each input (IN) of the plurality of inputs (IN1-INn), a circuit, which includes a controllable switch (SS) and a capacitor (CHOLD) , is operatively associated, the controllable switch (SS) being switchable between a first position, in which the capacitor (CHOLD) is connected to a voltage source (VDD), and a second position, in which the capacitor (CHOLD) is connected to the respective group of electrodes (J1-Jn), and the controller (24) is configured to switch the switch (SS) from the first position to the second position, in order to discharge the capacitor (CHOLD) in a manner proportional to the value of electrical capacitance associated with the group of electrodes (J4, J21, J38; J20, J37, Jn).
[0006]
6. Level sensor according to claim 2, characterized in that with each input (IN) of the plurality of inputs (IN1-INn), a circuit, which includes a controllable switch (SS) and a capacitor (CHOLD) , is operatively associated, the controllable switch (SS) being switchable between a first position, in which the capacitor (CHOLD) is connected to a voltage source (VDD), and a second position, in which the capacitor (CHOLD) is connected to the respective group of electrodes (J1-Jn), and the controller (24) is configured to switch the switch (SS) from the first position to the second position, in order to discharge the capacitor (CHOLD) in a manner proportional to the value of electrical capacitance associated with the corresponding group of electrodes (J4, J21, J38; J20, J37, Jn).
[0007]
7. Level sensor, according to claim 5, characterized in that the controller (24) has: a measuring circuit, to determine a voltage at said input (IN) with the switch (SS) in the second position, and a comparison circuit, to compare the voltage determined at said input (IN) with at least one corresponding reference threshold (THD, TH1, TH2, TH3), to deduce whether the medium (L) faces or does not face an electrode of the group. of electrodes (J4, J21, J38; J20, J37, Jn).
[0008]
8. Level sensor, according to claim 7, characterized in that each group of electrodes comprises at least a first electrode (J4) and a second electrode (J21) connected in parallel to each other, and the comparison circuit is preconceived to compare the voltage determined at said input (IN) with at least two corresponding reference limits, in order to deduce whether the medium (L) faces or does not face the first electrode (J4) and/or the second electrode (J21).
[0009]
9. Level sensor, according to claim 7, characterized in that the reference limits (THD, TH1, TH2, TH3; TH1, TH2, TH3) are of a number corresponding to the number of electrodes of said increased group in one, or else of a number corresponding to the number of electrodes in said group, and the comparison circuit is preconceived to compare the voltage determined at said input (IN) with each of the reference limits, to deduce if each one of the electrodes (J4, J21, J38) of said group faces or does not face the middle (L).
[0010]
10. Level sensor according to claim 6, characterized in that the voltage determined at said input (IN) is a differential voltage, the measuring circuit being preconceived to calculate the difference between the voltage value detected at said input (IN) and the voltage value detected at an input (IN1) of the plurality of inputs (IN1-INn), which is connected to at least one reference electrode (J1), and the comparison circuit is preconceived to compare the value voltage differential with said reference limit or with each of said reference limits (THD, TH1, TH2, TH3; TH1, TH2, TH3).
[0011]
11. Level sensor according to claim 1, characterized in that at least a portion of an electrically insulating substrate (20) rests against the insulating layer (16; 16") on a face thereof provided with the plurality of electrodes (J1-Jn).
[0012]
12. Level sensor according to claim 1, characterized in that between the insulating layer (16; 16") and the face of an electrically insulating substrate (20), containing the plurality of electrodes (J1-Jn ), a filling material (G) is present (G), the filling material (G) being disposed between the insulating layer (16; 16") and said face and/or front of the electrodes (J).
[0013]
13. Level sensor according to claim 1, characterized in that the set of capacitive elements is contained in an enclosure (16), which is electrically insulating and fluid-proof, defining at least one said layer of insulation and configured to be disposed within the reservoir (1) according to the geometric detection axis (X), the housing being preferably a housing (16) defining a respective cavity (H) for the insertion of the electrically insulating substrate (20) containing the electrodes (J1-Jn), or being a molded casing over at least a part of the electrically insulating substrate (20) containing the electrodes (J1-Jn).
[0014]
14. Level sensor, according to any one of the preceding claims, characterized in that it comprises at least one of: - a sensor body (10a) defining a connecting portion (14) configured for a sealed coupling in a respective mounting opening (5) of the reservoir (1); - a sensor body (10a) at least partially formed of a moldable thermoplastic material; - a sensor body (10a) defining a cavity (H) for receiving a substrate electrically insulating (20), the cavity (H) having elements to guide and/or position (12c, 16a) the substrate (20); - a sensor body (10a) having a connector (12a) with electrical terminals (21) , in which an electrically insulating substrate (20) has electrical contacts (22) configured for elastic coupling or insertion with the terminals (21) of the connector (12a); - a sensor body (10a) having positioning elements (16a) ) configured to push at least a portion (20b) d and an electrically insulating material (20) containing electrodes (J1-Jn) towards the insulating layer (16; 16"); - a sensor body (10a) having a coupling arrangement (12d) preconceived for quick coupling to a wall (2, 4) of the reservoir (1); - a sensor body (10a) having a pre-designed distal end for releasable coupling with a wall of the reservoir (1).
[0015]
15. Level sensor according to claim 1, characterized in that the electrically insulating substrate (20) containing the electrodes (J1-Jn): - has a first portion (20b) containing the plurality of electrodes ( J1-Jn) and a second portion (20a) containing a circuit arrangement (23) including the controller (24) on the substrate, preferably being provided with electrically conductive rails (25) for the electrical connection of the electrodes ( J1-Jn), and/or- has at least one temperature sensor (26, 27) associated therewith, and/or- has a distal end, which is spaced from a distal end of a corresponding housing (16), particularly to compensate for possible expansions, and/or- has at least one reference electrode (J1) associated with it, in at least one of a portion of the distal end thereof and a portion of the proximal end thereof, and/or- has a plurality of reference electrodes (J1, Jn; J18, J35) associated a thereto, so that at least two reference electrodes (J1, Jn) each at a respective end of a set of the plurality of electrodes (J1-Jn), or else the reference electrodes (J18, J35) are interposed with subsets of sensing electrodes (J2-J37; J19-J34, J36-Jn), and/or- has a plurality of reference electrodes associated with it (J1, J18, J35, Jn), each connected to a respective input (IN) of the controller (24) or else at least some of which are connected in parallel (J18, J35) to the same input (IN) of the controller (24), and/or have first electrodes of the plurality of electrodes (J1-Jn), which are closer to one of the others in the direction of a geometric detection axis (X) compared to the second electrodes of the plurality of electrodes (J1-Jn), the first electrodes determining a higher level measurement resolution than that determined by the second electrodes.
[0016]
16. Level sensor, according to claim 1, characterized in that the controller (24) is preconceived to detect one or more of the following conditions: - the medium (L) contained in the reservoir (1) is entirely in the fluid state; - the medium (L) contained in the reservoir (1) has gone entirely from a fluid state to a solid or frozen state; - the medium (L) contained in the reservoir (1) has a predominant fluid part, in which the parts of the medium are floating or submerged, which are in the solid or frozen state ("iceberg effect"); - the medium (L) contained in the reservoir (1) is in the phase of passage from a fluid state to a state solid or vice versa, such as freezing or thaw; - the medium (L) contained in the reservoir (1) includes at least one part in a solid or frozen state (I) and a second part in a fluid or liquid state ( L), with a layer (A) of air or gas being interposed between the first part (I) and the second part (L) ("eff igloo");- the medium (L) contained in the reservoir (1) comprises at least a part in a solid or frozen state, with a part above in a fluid or liquid state.
[0017]
17. Method for controlling a level sensor of a medium (L) contained in a reservoir (1), the sensor having a plurality of electrodes arranged according to an assembly (J1-Jn), which extends according to an axis geometric detection (X) of the medium level (L), comprising the steps to:i) obtain electrical signals through the first electrodes (J21, J37), which do not face the medium (L);ii) obtain electrical signals through a variety of second electrodes (J38, Jn), which are above a first considered electrode (J37); characterized by: iii) verifying that, above the first considered electrode (J37), at least one electrode that faces the medium (L) is present, among the above-mentioned second electrodes (J38, Jn), and in this way to deduce that the medium (L) contained in the reservoir (1) comprises at least a part in the solid or frozen state (I), the which is above a layer of air or gas (A), in which step iii) comprises:- calculating the difference between the values of electrical signals obtained through said second electrodes (J38, Jn) and the value of the electrical signal obtained through the first electrode considered (J37), and compare the unit results with at least one defined limit, and if at least one of the differences coincide or are within a certain proximity of the defined limit, deduce that the medium (L) contained in the reservoir (1) comprises at least a part in the solid or frozen state (I), which is above a layer of air or gas (A).
[0018]
18. Level sensor for detecting the level of a medium contained in a reservoir (1), the sensor (10) comprising: a set of capacitive elements designed to be associated with the reservoir (1), to extend in accordance with a geometric detection axis (X) of the middle level, the set of capacitive elements comprising a plurality of electrodes (J1-Jn) on one face of a substantially insulating substrate (20) having a generally elongated shape, the electrodes (J1- Jn) being spaced apart from each other along the geometric detection axis (X) and being essentially coplanar to each other, at least one insulating layer (16; 16") to electrically insulate the electrodes (J1-Jn) from the interior of the reservoir (1), a controller (23, 24) having a plurality of inputs (IN1-IN), the controller (24) being preconceived to deduct the level of the medium (L) present in the reservoir (1) based on the electrical signals obtained, in which each element cap active comprises at least one unitary electrode (J) and a group of electrodes connected in common to each other (J4-J21; J38-J20, J37-Jn), in particular, in parallel, the unit electrode (J) or the group of electrodes (J4-J21; J38-J20, J37-Jn) being connected to a respective input (IN) of the plurality of inputs (IN1-INn), in which the controller (23, 24) is predisposed to discriminate a value of the electrical capacitance associated with each electrode to deduce the level of the medium present in the reservoir, characterized by the fact that:- between the layer of insulation (16; 16") and the face of an electrically insulating substrate (20) containing the plurality of electrodes (J1-Jn), a filler material (G) is present, the filler material (G) being arranged between the insulation layer (16; 16") and said face and/or front of the electrodes (J1-Jn), and/or - the level sensor comprises a sensor body (10a) having positioning elements ( 16a) configured to push at least a portion of an electrically insulating material (20) containing the electrodes (J1-Jn) towards the insulating layer (16; 16"), the positioning elements (16a) being elastically producible and/or deformable.
[0019]
19. Reservoir, in particular a tank, characterized in that it is preconceived for coupling with a level sensor as defined in claim 1.

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同族专利:

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公开号 | 公开日

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CN107076597A|2017-08-18|

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引用文献:

---

公开号 | 申请日 | 公开日 | 申请人 | 专利标题

---

---

KR100535680B1|2001-07-13|2005-12-09|삼성전자주식회사|Sensor for detecting water level|

---

DE10261767A1|2002-12-19|2004-07-15|Hydac Electronic Gmbh|Device and method for measuring capacitance and device for determining the level of a liquid with such a device|

---

US7258005B2|2004-02-06|2007-08-21|David Scott Nyce|Isolated capacitive fluid level sensor|

---

US20080250796A1|2005-02-15|2008-10-16|Control Devices, Inc.|Methods and Apparatus for Detecting and Making Ice|

---

FR2892509B1|2005-10-26|2007-12-21|Inergy Automotive Systems Res|CAPACITIVE GAUGE FOR FUEL TANK|

---

US7729870B2|2007-09-05|2010-06-01|Yizhong Sun|Methods for detecting oil deterioration and oil level|

---

US7863909B2|2008-03-04|2011-01-04|Synaptics Incorporated|System and method for measuring a capacitance by transferring charge from a fixed source|

---

US7963164B2|2008-06-09|2011-06-21|Rochester Gauges, Inc.|Capacitive sensor assembly for determining level of fluent materials|

---

GB0909510D0|2009-06-03|2009-07-15|Airbus Uk Ltd|Fuel level measurement apparatus and method|

---

JP5212417B2|2010-04-12|2013-06-19|三菱電機株式会社|Power semiconductor module|

---

KR101031498B1|2010-07-09|2011-04-29|주식회사 켐트로닉스|Apparatus and method for sensing change of capacitance and computer readable record-midium on which program for excuting method thereof, apparatus and method for sensing touch using the same and computer readable record-midium on which program for excuting method thereof|

---

CN102401676A|2010-09-16|2012-04-04|苏州工业园区天驰自控仪表有限公司|Measurement converting device|

---

TWI428612B|2010-12-10|2014-03-01|Elan Microelectronics Corp|A circuit for sensing a capacitance to be measured and a method thereof|

---

EP2549619A1|2011-07-19|2013-01-23|Kabushiki Kaisha Toyota Jidoshokki|Charge and discharge control apparatus|

---

CN102944287B|2012-11-23|2016-04-13|江苏南水科技有限公司|Capacitance type flexible electronic tide staff|

---

CN103017863A|2012-12-12|2013-04-03|重庆德格科技发展有限公司|Parallel-plate multi-electrode capacitance type oil level sensor|US11015245B2|2014-03-19|2021-05-25|Asm Ip Holding B.V.|Gas-phase reactor and system having exhaust plenum and components thereof|

---

US10458018B2|2015-06-26|2019-10-29|Asm Ip Holding B.V.|Structures including metal carbide material, devices including the structures, and methods of forming same|

---

US10211308B2|2015-10-21|2019-02-19|Asm Ip Holding B.V.|NbMC layers|

---

ITUB20159220A1|2015-12-24|2017-06-24|Eltek Spa|DEVICE AND METHOD FOR DETECTION OF THE LEVEL OF A MEDIA|

---

US11139308B2|2015-12-29|2021-10-05|Asm Ip Holding B.V.|Atomic layer deposition of III-V compounds to form V-NAND devices|

---

ITUA20161342A1|2016-03-04|2017-09-04|Eltek Spa|SENSOR DEVICE FOR CONTAINERS OF LIQUID SUBSTANCES|

---

ITUA20161345A1|2016-03-04|2017-09-04|Eltek Spa|SENSOR DEVICE FOR CONTAINERS OF LIQUID SUBSTANCES|

---

US10381693B2|2016-03-24|2019-08-13|Flow-Rite Controls, Ltd.|Liquid level sensor for battery monitoring systems|

---

ITUA20163239A1|2016-04-18|2017-10-18|Eltek Spa|DEVICE FOR DETECTION OF THE LEVEL OF A MEDIA|

---

DK3505877T3|2016-04-21|2020-11-16|Hewlett Packard Development Co|INK LEVEL REGISTRATION|

---

US10367080B2|2016-05-02|2019-07-30|Asm Ip Holding B.V.|Method of forming a germanium oxynitride film|

---

US9859151B1|2016-07-08|2018-01-02|Asm Ip Holding B.V.|Selective film deposition method to form air gaps|

---

US9887082B1|2016-07-28|2018-02-06|Asm Ip Holding B.V.|Method and apparatus for filling a gap|

---

KR20180013034A|2016-07-28|2018-02-07|에이에스엠 아이피 홀딩 비.브이.|Substrate processing apparatus and method of operating the same|

---

US10408660B2|2016-08-11|2019-09-10|Orscheln Products L.L.C.|Electronic fluid level indicator|

---

KR20180068582A|2016-12-14|2018-06-22|에이에스엠 아이피 홀딩 비.브이.|Substrate processing apparatus|

---

KR20180070971A|2016-12-19|2018-06-27|에이에스엠 아이피 홀딩 비.브이.|Substrate processing apparatus|

---

US10269558B2|2016-12-22|2019-04-23|Asm Ip Holding B.V.|Method of forming a structure on a substrate|

---

CN109249618A|2017-07-14|2019-01-22|三纬国际立体列印科技股份有限公司|Three-dimensional printing device and level sensing methods|

---

KR20190009245A|2017-07-18|2019-01-28|에이에스엠 아이피 홀딩 비.브이.|Methods for forming a semiconductor device structure and related semiconductor device structures|

---

US10541333B2|2017-07-19|2020-01-21|Asm Ip Holding B.V.|Method for depositing a group IV semiconductor and related semiconductor device structures|

---

US11018002B2|2017-07-19|2021-05-25|Asm Ip Holding B.V.|Method for selectively depositing a Group IV semiconductor and related semiconductor device structures|

---

IT201700082600A1|2017-07-20|2019-01-20|Eltek Spa|DEVICE FOR DETECTION OF THE LEVEL OF A MEDIA|

---

IT201700082500A1|2017-07-20|2019-01-20|Eltek Spa|DEVICE FOR DETECTION OF THE LEVEL OF A MEDIA|

---

IT201700082457A1|2017-07-20|2019-01-20|Eltek Spa|DEVICE FOR DETECTION OF THE LEVEL OF A MEDIA|

---

US11139191B2|2017-08-09|2021-10-05|Asm Ip Holding B.V.|Storage apparatus for storing cassettes for substrates and processing apparatus equipped therewith|

---

US11056344B2|2017-08-30|2021-07-06|Asm Ip Holding B.V.|Layer forming method|

---

KR20190023920A|2017-08-30|2019-03-08|에이에스엠 아이피 홀딩 비.브이.|Substrate processing apparatus|

---

US10403504B2|2017-10-05|2019-09-03|Asm Ip Holding B.V.|Method for selectively depositing a metallic film on a substrate|

---

US11022879B2|2017-11-24|2021-06-01|Asm Ip Holding B.V.|Method of forming an enhanced unexposed photoresist layer|

---

KR20200089659A|2017-11-27|2020-07-27|에이에스엠 아이피 홀딩 비.브이.|Storage device for storing wafer cassettes for use with batch furnaces|

---

US11081345B2|2018-02-06|2021-08-03|Asm Ip Holding B.V.|Method of post-deposition treatment for silicon oxide film|

---

US11114283B2|2018-03-16|2021-09-07|Asm Ip Holding B.V.|Reactor, system including the reactor, and methods of manufacturing and using same|

---

US11088002B2|2018-03-29|2021-08-10|Asm Ip Holding B.V.|Substrate rack and a substrate processing system and method|

---

US11230766B2|2018-03-29|2022-01-25|Asm Ip Holding B.V.|Substrate processing apparatus and method|

---

FR3079610B1|2018-03-30|2020-03-20|Mgi Coutier|DEVICE FOR MEASURING A PHYSICAL PARAMETER OF A FLUID OF A MOTOR VEHICLE CIRCUIT|

---

TW202013553A|2018-06-04|2020-04-01|荷蘭商Ａｓｍ 智慧財產控股公司|Wafer handling chamber with moisture reduction|

---

KR20190140613A|2018-06-12|2019-12-20|현대자동차주식회사|Device and method for monitoring liquid level of liquid storage tanks for vehicle|

---

US10612136B2|2018-06-29|2020-04-07|ASM IP Holding, B.V.|Temperature-controlled flange and reactor system including same|

---

US11053591B2|2018-08-06|2021-07-06|Asm Ip Holding B.V.|Multi-port gas injection system and reactor system including same|

---

US11049751B2|2018-09-14|2021-06-29|Asm Ip Holding B.V.|Cassette supply system to store and handle cassettes and processing apparatus equipped therewith|

---

US11232963B2|2018-10-03|2022-01-25|Asm Ip Holding B.V.|Substrate processing apparatus and method|

---

KR20200045067A|2018-10-19|2020-05-04|에이에스엠 아이피 홀딩 비.브이.|Substrate processing apparatus and substrate processing method|

---

US11087997B2|2018-10-31|2021-08-10|Asm Ip Holding B.V.|Substrate processing apparatus for processing substrates|

---

US11031242B2|2018-11-07|2021-06-08|Asm Ip Holding B.V.|Methods for depositing a boron doped silicon germanium film|

---

US10847366B2|2018-11-16|2020-11-24|Asm Ip Holding B.V.|Methods for depositing a transition metal chalcogenide film on a substrate by a cyclical deposition process|

---

RU2695588C1|2018-11-18|2019-07-24|Александр Александрович Калашников|Method of measuring liquid level and device for its implementation |

---

US11217444B2|2018-11-30|2022-01-04|Asm Ip Holding B.V.|Method for forming an ultraviolet radiation responsive metal oxide-containing film|

---

US11158513B2|2018-12-13|2021-10-26|Asm Ip Holding B.V.|Methods for forming a rhenium-containing film on a substrate by a cyclical deposition process and related semiconductor device structures|

---

KR20200091543A|2019-01-22|2020-07-31|에이에스엠 아이피 홀딩 비.브이.|Semiconductor processing device|

---

CN111524788A|2019-02-01|2020-08-11|Asm Ip私人控股有限公司|Method for topologically selective film formation of silicon oxide|

---

KR20200102352A|2019-02-20|2020-08-31|에이에스엠 아이피 홀딩 비.브이.|Cyclical deposition method including treatment step and apparatus for same|

---

TW202044325A|2019-02-20|2020-12-01|荷蘭商Ａｓｍ Ｉｐ私人控股有限公司|Method of filling a recess formed within a surface of a substrate, semiconductor structure formed according to the method, and semiconductor processing apparatus|

---

DE102019104753A1|2019-02-25|2020-08-27|Schlüter Automation und Sensorik GmbH|Level measuring device|

---

KR20200108243A|2019-03-08|2020-09-17|에이에스엠 아이피 홀딩 비.브이.|Structure Including SiOC Layer and Method of Forming Same|

---

USD935572S1|2019-05-24|2021-11-09|Asm Ip Holding B.V.|Gas channel plate|

---

USD922229S1|2019-06-05|2021-06-15|Asm Ip Holding B.V.|Device for controlling a temperature of a gas supply unit|

---

USD944946S1|2019-06-14|2022-03-01|Asm Ip Holding B.V.|Shower plate|

---

USD931978S1|2019-06-27|2021-09-28|Asm Ip Holding B.V.|Showerhead vacuum transport|

---

US11227782B2|2019-07-31|2022-01-18|Asm Ip Holding B.V.|Vertical batch furnace assembly|

---

USD940837S1|2019-08-22|2022-01-11|Asm Ip Holding B.V.|Electrode|

---

USD930782S1|2019-08-22|2021-09-14|Asm Ip Holding B.V.|Gas distributor|

法律状态:
2020-06-09| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-06-01| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

---

2021-08-03| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 28/05/2015, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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ITTO2014A000439|2014-05-30|

---

ITTO20140439|2014-05-30|

---

PCT/IB2015/054020|WO2015181770A2|2014-05-30|2015-05-28|A sensor for detecting the level of a medium|

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