• 专利附录
  • 专利说明
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    • 专利摘要:
    The method according to the invention provides for the gravimetric weighing to be continued during the refilling of a gravimetric dosing device (1) for bulk material, for additionally determining the refilled bulk material mass via a refilling container (3) during the refilling and thus in real time or on average the output during the refilling -Mass flow to determine. The invention also relates to a gravimetric metering device for bulk goods.
    公开号:CH715328A2
    申请号:CH01566/18
    申请日:2018-12-19
    公开日:2020-03-13
    发明作者:Helfenstein Urs；Ludescher Stefan
    申请人:K Tron Tech Inc；
    IPC主号:
    专利说明:

    The present invention relates to a method for regulating the mass flow of a metering device for bulk goods according to the preamble of claim 1 and a metering device for carrying out this method according to the preamble of claim 12.
    The gravimetric feeders also known as differential weigh feeders are widely used and used in many branches of industry for all kinds of pourable materials, i. Bulky goods, insofar as they can even be conveyed by a gravimetric feeder. The pourable materials are put into a storage container and then dosed out of this via an output conveyor. The doser is on a scale, so the weight registered by the scale is the gross weight, i.e. the known and constant weight of the components of the feeder (tare) plus the variable weight of the bulk material currently in the storage container (net weight).
    Thus, the scales continuously register the weight loss of the entire doser during operation of the doser, and thus the weight decrease in the reservoir because of the constant weight of the doser, so that a control of the doser from the weight decrease determines the actual mass flow of the pourable material output and can regulate the output conveyor accordingly in comparison with a predetermined target mass flow in order to minimize the difference between the actual and the target mass flow.
    A very precise regulation of the output mass flow may be necessary, for example in the field of pharmacy or when color pigments are to be mixed in in industrial production. In addition, the target mass flow rate can be small, for example in the case of the color pigments mentioned and in the manufacture of drugs, or large, for example in the field of plastics production and in mining.
    If the mass flow output from the doser is to be continued without interruption, the reservoir must be refilled periodically while the dosing is running. A refilling station then fills this with bulk material as soon as a predetermined lower level is detected gravimetrically (i.e. via the weight loss in the storage container), and refilling stops as soon as the storage container has reached its filling weight or the amount measured by a level in the refill container the reservoir has been dispensed. As a rule, the refilling station is located above the storage container, so that for refilling, for example, a slide or a differently designed valve in the line between the storage container and the refilling station can be opened and closed again.
    During the refilling, the gravimetric control is blind, since the balance no longer registers a decrease in weight corresponding to the actual mass flow output, but an increase in weight that is marked by considerable disturbances. Depending on the dynamic behavior of the scales used, these disturbances last for a shorter or longer period beyond the end of the refill, so that gravimetric dosing can only be resumed when the scales have calmed down again after the refill is complete. This blind time window can last about 5 seconds to 5 minutes, depending on the type of bulk material, the target mass flow and the dosing device or refilling station used.
    Since gravimetric dosing is not possible in the prior art during refilling, a volumetric control is used, i. E. the output conveyor is controlled by the volume of bulk material it is conveying, in which case the nature of the matter, for example, does not take into account the density or compression of the bulk material. Using the example of the screw conveyors that are often used, this means that the control of the screw speed is set according to the volume of the target mass flow, i.e. according to the volume between the turns of the screw (volumetric conveyance) and no longer according to the weight loss of the storage container (gravimetric conveyance).
    Volumetric conveying has the disadvantage that, in contrast to gravimetric control, the fluid dynamic behavior of the bulk material moved by refilling and dosing itself cannot be recorded, i.e. the volumetrically controlled mass flow of bulk material cannot be regulated if the mere regulation of the speed of the screw conveyors or the operating speed of the output conveyor is disregarded. However, the behavior of the moving bulk material has a decisive influence on the volumetrically generated mass flow: for example, as mentioned above, various bulk materials compress strongly under pressure (others less), so that their mass per unit volume is dependent on the fill level of the storage container, which is one thing with volumetric conveyance different mass flow depending on the level.
    The brochure “K-Tron Smart Refill Technology” from 2009 shows on page 2, Fig. 3 “Dynamics of the refill operation” a volumetric control model for the output conveyor, which takes into account the compression of the bulk material below in the area of the screw conveyor arising from the height of the column of material, ie the level of the storage container results. During the gravimetric conveying, the gravimetric control regulates the screw speed down when the fill level is high (i.e. compacted bulk material) and then increases this in turn with a decreasing fill level (i.e. decreasing compression). A screw speed can thus be assigned to each filling level while the storage container is being emptied. For refilling, when a refilling station dispenses powder quickly and in large quantities into the storage container, a suitable curve for the rise in the fill level is now assumed (usually a straight line) and the screw speed determined during the emptying of the storage container is assigned to this fill level curve. with which the screw speed decreases accordingly during refilling until the storage container is filled. The error during the volumetric conveyance is correspondingly reduced compared to a constant screw speed, but not eliminated, since the true conditions in the storage container are still unknown during the refilling.
    In addition, it is proposed in this prospectus on page 4 in Fig. 4 “Refill Frequency” to increase the refill frequency up to 60 refills per hour. This means that the individual refilling time is reduced, i.e. the dosing error during operation with the volumetric control model can be reduced. It can be assumed that the total refill time per hour remains constant regardless of the refill frequency. However, it is the case that if the refilling takes longer, the deviation between the target and the actual value increases, i.e. the dosing error more and more serious. For most applications, more frequent but small dosing errors can now be tolerated, since these remain in the specification, while rarer but larger dosing errors lead out of the specification and are therefore unacceptable. The volumetric control model, which takes into account the compression on the basis of data from the previous emptying of the storage container, in conjunction with a high refilling frequency, enables comparatively good dosing during refilling for certain applications. However, the volumetric controller model that takes into account the compression is disadvantageous in that considerable metering errors still occur during refilling, i.e. Dosing errors that are greater than those that occur during gravimetric dosing. It is particularly disadvantageous that the dosing error itself is still not known, even if it can be reduced in size by a volumetric control model with an increased refill frequency. The mere existence of an unknown dosing error can result in a quality problem, for example in pharmacy or with color mixtures (see above), even if a dosing error should be permissible per se.
    In WO 2013/182 869 it is proposed on page 7 to store data during the refill, to give the same amount of powder in the storage container for the refill and to operate the output conveyor according to the data stored in a previous refill have been. Thanks to the same refilling conditions, it is possible to collect data at the outlet of the feeder and to regulate the speed of the output conveyor accordingly. However, there is no suggestion of what kind of data this could be, nor how data can be recorded at all at the outlet of the dispenser. U.A. The principle of gravimetric dosing overcomes the problem that the throughput in kg / h of a bulk material flow can only be measured with considerable effort - this would also mean that an additional measuring station would have to be provided behind the doser. Furthermore, it remains unclear how a controller model would have to be structured for the next refill if data could actually be collected at the outlet of the dispenser.
    Accordingly, it is the object of the present invention to provide a metering device for bulk goods that allows the metering error to be determined during refilling. This object is achieved by a method with the features of claim 1 or by a dispenser with the features of claim 14.
    The fact that the bulk material weight output into the storage container during the refilling is detected in the refilling station, this can be determined independently of the disturbances occurring in the dispenser during refilling. Because the increase in the bulk material weight that occurred during the refilling in the storage container is determined, the actual mass flow of the bulk material weight that has flowed off via the output conveyor can be determined from the difference to the refilled bulk material weight. Since the measurement only has to be made of the increase in the bulk material weight in the storage container, the considerable disturbances of this measurement that occur during refilling can be suitably compensated as described below.
    In a further embodiment of the present invention according to claims 2 and 15, a dispenser for bulk goods is provided over the set task, which further allows a control of the actual mass flow output during refilling of the storage container. As a result, a dosing device with a regulation of the quantity of bulk material dispensed is also available during the refill phase, whereby the dispensing error (minimized due to the regulation) can optionally be dispensed in addition to the regulation.
    [0015] Further preferred embodiments have the features of the dependent claims.
    The invention is described in more detail below with reference to the figures.
    It shows: Fig. 1 schematically a dispenser according to the invention, Fig. 2a a flow chart for determining the metering error of the dispensed during refilling from the dispenser of Fig. 1 mass flow Fig. 2b a flow chart for regulating the during refilling from the dispenser 1, FIG. 3 is a flow chart for calculating an adjusted weight of the bulk material in the storage container of the dosing device from FIG. 1, FIG. 4 is a diagram for determining the delay in weight increase in the storage container of the dosing device from FIG. 1, and FIG. 5 shows a flow chart for a further embodiment of the regulation of the mass flow output from the dispenser of FIG. 1 during the refilling.
    Fig. 1 shows schematically a metering device 1 according to the invention with a refill station 2 with a refill container 3 for the bulk material to be conveyed and dosed. The dosing device 1 has a storage container 4 for the bulk material, as well as an output conveyor, designed here as a screw conveyor 5, for the bulk material. This is shown cut open so that a screw conveyor 6 can be seen. At this point it should be mentioned that other output conveyors are also in accordance with the invention, such as disk or vibration conveyors.
    Via a connecting channel 7 between the refill container 3 and the storage container 4, this bulk material can be refilled, which in turn is delivered by the screw conveyor 6 driven by a motor 8 via a discharge line 9 as a uniformly metered mass flow. For this purpose, the motor 8 is regulated via a controller 10. This does not necessarily have to be arranged on the dosing unit 1, but can be located anywhere in the production line, e.g. are at the line control. To relieve the figure, the data lines between it and the relevant components of the dispenser 1 and the refill station 2 that are necessary for the operation of the control have been omitted.
    The doser 1 rests on several gravimetric (i.e. gravimetric dosing serving) scales 11 (but only one gravimetric scale can be provided), which in turn are arranged via a support beam 12 on a frame 13 of the production line. Likewise, in the embodiment shown here, the refill container 3 rests according to the invention on refill scales 14 which are arranged on the frame 13. In the embodiment shown, the connecting channel 7 has a slide 15 which can be opened to refill the storage container 4 and which remains closed while it is being emptied. Other closing devices, such as a rotary valve, can also be provided. A bellows 16 is also provided, which mechanically decouples the storage container 4 (and thus the dosing device 1) from the refilling station 2, so that the gravimetric scales 11 only detect the weight of the dosing device 1. Such a bellows 16 is also provided in front of the line 9, which conveys the evenly metered mass flow of the bulk material.
    The structure of this arrangement described above is basically known to the person skilled in the art, as are the two operating modes used: Once the gravimetric operating mode, in which the storage container is emptied and the weight loss of the doser 1 corresponds to the actual mass flow of the bulk material (since the weight of the doser 1 itself is constant), a gravimetric control model in the controller 10 regulating the conveying capacity of the screw conveyor 6 with regard to the target mass flow. Then the volumetric operating mode, in which the storage container is refilled with blind gravimetric control. Instead of the regulation, there is then a volumetric control model, which is preferably based on the data for regulation during the gravimetric operation, as described above, but, as mentioned, the non-regulatable actual mass flow deviates from the target mass flow greater than this is the case in gravimetric mode.
    FIG. 1 also shows a pressure sensor 20 for the internal pressure prevailing in the storage container 4. During the more or less sudden refilling of the storage container, the air pressure in it increases accordingly. If the gravimetric operation is resumed after the refilling, an increased pressure continues for a short time in a closed system in which the storage container 4 is not open to the environment. This is often also the case when an overpressure channel is provided between the storage container 4 and the refill container 3, since this (or the lines preceding it upstream) often cannot take over the function of an expansion vessel. This means that when changing from the volumetric to the gravimetric mode, the weight registered by the gravimetric scales 11 is even higher than it corresponds to the bulk material in the storage container 4. The reason for this is that the slide 15 of the refill station 2 is (necessarily) suspended from the refill container 3 on the frame 13, so that the product of the cross-sectional area of the connecting channel 7 times the currently prevailing overpressure results in an additional, distorting force on the gravimetric scales 11 . It is known to the person skilled in the art to recognize an increased air pressure in the storage container 3 via the pressure sensor 20 at the beginning of the gravimetric mode and to avoid incorrect gravimetric dosing.
    A pressure sensor 21 on the output line 22 can also be seen, via which pressure fluctuations prevailing in this can be detected and processed by the controller 10 analogously to the pressure fluctuations in the storage container 4.
    The applicant has found that during the refill, in addition to the pressure fluctuations in the storage container 4, further disturbances occur which undesirably affect the mass flow output during the refill:
    This includes, for example, the pulse of the bulk material falling from the height of the refill container 3 to the bottom of the storage container 4, and this disruption can be different. Firstly, the pulse generates a force on the storage container 4, which is recognized by the gravimetric scales as weight (weight by pulse), so that the controller 10 detects an incorrect bulk material mass in the storage container 4. Second, the impulse also compresses the bulk material lying under the falling bulk material, i.e. beyond the compression corresponding to the level (compression by pulse). Thirdly, the bulk material can also be driven through the impulse by the rotating screw in the conveying direction (or by a differently structured output conveyor) (additional conveyance by impulse). Conversely, it can result that the bulk material swirls during the fall into the storage container 4, the momentum changes as a result and fluidization of the bulk material occurs in the storage container 4 (reduced conveyance by fluidization). Finally, a short-term bridging of the bulk material can occur during refilling, both in the storage container 4 or in the refill container 3, so that the refill quantity is influenced, first when the bridges are built, then when they collapse (changed conveyance due to incorrect material flow).
    Depending on the material, all of these disturbances occur during a refill phase or during the entire refill, equally or differently, individually or in combination, then accumulate or alternately partially offset each other. The ambient conditions can influence these disturbances, for example through the temperature, the air pressure or the air humidity, so that, for example, depending on the time of day, this creates an additional drift in the mass flow of bulk material metered during refilling.
    Fig. 1 now shows according to the invention in the embodiment shown as scales 14 sensors for a parameter for the output refill of the refill station 2. The refill container 3 rests on the refill scales 14. This allows not only that for a refill in Determine the total weight of the bulk material outputted to the storage container 4, but also the mass flow of the bulk material during the refilling itself. The applicant has found that disturbances occurring in the storage container 4 during the refilling can be detected and eliminated mathematically in the control or at least significantly reduced if during During the refill, it is not the bulk material weight filled into the storage container 4, but the bulk material weight output from the refill container 3 that is recorded, see FIG. the description below.
    The result is a gravimetric doser according to the invention with a storage container for the bulk material to be dosed and a refill station connected to this, which is designed to refill a refill amount of bulk material into the storage container and is provided with a sensor for a parameter for the refill amount at least one scale, which is operably connected to the storage container and an output conveyor for the bulk material for gravimetric dosing of the bulk material, and with a control for the output conveyor which is designed to control it during a refilling phase according to a volumetric control model, wherein the control is further developed, during the refill, the bulk material weight output by the refill station from the signals of the sensor for the refill quantity, and a value for the weight of the bulk material currently present in the storage container from the weight signal of the at least one gravimetric scale ts and from this to determine an actual bulk material flow.
    In a further embodiment according to the invention, the control is further designed to determine a correction factor for the volumetric control model from the difference between a target flow of bulk material and the actual flow of bulk material and to apply it to this.
    FIG. 2a shows a flow chart for the inventive determination of the metering error of the mass flow output by the metering device 1 (FIG. 1) during the refilling of its storage container 4.
    In step 30, the refilling is triggered by the controller 10, for example when the weight signal of the scales 11 corresponds to a lower level of the storage container 4. As a result, the controller 10 switches in step 31 to the volumetric control model stored in it, described above, and opens the valve in the refill channel 7, designed here as a slide 15, so that a refill mass flow of bulk material flows into the refill container. The refill scales 14 accordingly register a reduction in the weight of the refill container 3, from which the controller 10 in step 32 determines the bulk material mass refilled into the storage container 4.
    According to the invention, the controller 10 now processes the weight signals from the gravimetric scales 11, but these are heavily falsified due to the disturbances occurring during the refill, i.e. no longer correspond to the bulk material present in the storage container 4. Correspondingly, in step 33, the mass of bulk material in the storage container 4 that has been cleared of faults must be determined (see also the description of FIG. 3).
    If at a point in time the (true or approximately true) weight of the bulk material present in the storage container 4 and the weight of the refilled bulk material (by the scales 11 and 14) is known, the difference between these weights corresponds to one (compared to these weights) earlier point in time) the weight of the bulk goods output via the output conveyor. The derivation according to the time results in step 34 the refill mass flow, the change in the mass of the bulk material in the storage container 4 and the actual bulk material mass flow output by the metering device 1.
    The data on the actual bulk material flow can be stored in a data memory of the control or output in real time to the line control or to another instance in which the data on the ongoing dosing are processed further. With this data, there is complete traceability of the dosage without a “blind spot” during refilling, which, as described above, can be essential, especially in highly sensitive production (e.g. pharmacy or other applications).
    It should be noted at this point that the volumetric control model in the simple case contains a mere predetermined value for the target mass flow, and thus a simple, constant manipulated variable for the motor 8 (or for the drive of a differently designed output Conveyor) so that it controls the mass flow generated by the output conveyor via a predetermined value for a target mass flow. However, it can also contain, for example, a manipulated variable that is predetermined over the refilling period, for example during a preceding gravimetric emptying (or according to another suitable principle), as described above. It then controls the mass flow generated by the output conveyor using data on the compression of the bulk material while the storage container is being emptied.
    In step 36, the controller 10 checks, for example, based on the refilled mass of bulk material (scales 14) or based on the faults cleared bulk weight (scales 11), whether the reservoir contains the refill target amount of bulk material and breaks in the positive case in step 37 the refill off, ie switches to the gravimetric mode or, in the negative case, goes back to step 31 to continue the refilling.
    As a result, according to the invention, there is a (gravimetric) determination of the mass flow output by the dispenser 1 during the refill, the dispenser having a storage container and a refill station connected to it, designed for gravimetric dispensing via an output conveyor, the refill container The storage container is periodically refilled with bulk material from a lower level to a full state and provided with a sensor for a parameter for the dispensed refill quantity, while the refill is controlled by a volumetric control model, and the during refilling of the storage container in this refilled bulk material weight is determined from the data of the sensor for the refill quantity output from the refill station and the increase in the bulk material weight in the reservoir during the refilling of the storage container and from the difference between these weights of the currency The actual bulk material flow output at the end of the refill is calculated.
    FIG. 2b shows a flow chart for a further embodiment of the invention, namely for regulating the mass flow released from the dispenser of FIG. 1 during refilling, which is based on the determination of the actual bulk material flow according to the sequence of FIG. 2a.
    On the basis of the actual mass flow after step 34 (see also Fig. 2a), the controller 10 now additionally generates a current correction factor for the volumetric control model and thus for the manipulated variable in step 35 so that the actual mass flow to the Target mass flow is at least approximated or essentially corresponds to this.
    It thus results preferably that, further to regulate the mass flow, a correction factor for the volumetric control model is generated from the difference between a target flow of bulk goods and the actual flow of bulk goods and is applied to this. It is particularly advantageous that the data on the actual bulk material flow or actual mass flow are of course still available for traceability of the dosing during refilling, but at the same time the (now quantitatively measurable and traceable) dosing error itself is minimized during refilling.
    The sequence according to FIGS. 2a or 2b is preferably run through at least once, preferably several times, during the refilling, so that the actual bulk material flow can be determined several times and / or the correction factor generated several times and then applied to the volumetric control model in real time . For the specific case, the person skilled in the art can determine the cycle time of this cycle and thus the fineness of the regulation during the refilling, which can also be adjusted to the properties of the material to be dosed, among other things. The result is that the gravimetric feeder is preferably designed to determine the actual bulk material flow (sequence according to FIG. 2a) and / or the correction factor (sequence according to FIG. 2b) several times during refilling, with a correction factor determined in each case and in real time to apply to the volumetric control model in such a way that its value for the target bulk material flow is adjusted during the refill. It goes without saying that, as mentioned above, the dosing error can also be quantitatively recorded and output in the case of a bulk material flow regulated during refilling.
    Fig. 3 shows a flow chart for determining a fault-free bulk material weight in the storage container, i. to step 33 of FIG. 2. This further opens up the way of at least reducing or essentially eliminating the effects of the above-described disturbances on the mass flow output by the metering device by means of a correction factor representing a manipulated variable for the volumetric control model.
    The result is that the increase in the bulk material weight in the storage container is calculated during the refilling by means of a bulk material weight which has been cleared of disturbances.
    In Fig. 3 three branches 40 to 42 are shown, in which the controller 10 of the dosing device 1 (Fig. 1) each independent of the other branches 40 to 42 a cleanup of the gravimetric scales 11 (Fig. 1 ) detected, but falsified by a specific disturbance weight of the bulk material present in the storage container 4.
    Each branch 40 to 42 begins with step 30 as soon as the controller 10 starts the refill and ends with step 38, i. as soon as the reservoir 4 is filled. In each branch, according to step 43, the weight signal of the gravimetric scales 11 is recorded by the controller 10 during the refilling and used to determine the corrected weight.
    In branch 40, in step 45, the force acting on the storage container by the pulse of the refilled bulk material and recognized by the gravimetric scales 11 as weight is determined. For this purpose, the geometry of the refill channel 7 and the storage container 4, so that the height of fall of the bulk material, can be stored in the controller 10. From the signals of the refill scales 14, the controller 10 can determine the decreasing weight of the refill container 3 and from this the mass flow of the bulk material falling into the storage container 4. The impulse (or impulse current) follows from the height of fall and the mass flow and from this, in turn, the force acting over time through the impulse on the gravimetric scales 11, which generates the desired proportion of the weight detected by the gravimetric scales 11. In step 46 this force is subtracted from the detected weight and stored in the controller as a weight adjusted for the pulse. The result is that the adjusted bulk material weight during refilling is preferably calculated by the force exerted on the storage container via the impulse of the falling bulk material and that the control of the gravimetric feeder is preferably designed, adjusted for the impulse of the bulk material falling into the storage container To determine the bulk weight in the storage container. It should be noted that the signals from the refill scales 14 can indicate a slight pulsation that is generated, for example, by a refill screw conveyor. This pulsation is smoothed out by the free fall of the refilled powder. In the controller 10, a corresponding smoothing (possibly determined by tests) can then be assumed in real time, so that the amount of bulk material actually fed to the storage container is recorded with high precision.
    In branch 41, the current overpressure in the reservoir 4 is detected in step 47, from which the controller 10, through the geometry of the reservoir 4 and the refill channel 7 stored in it, determines the force with which the scales 11 are loaded by the excess pressure. In step 48, this force is subtracted from the detected weight and stored in the controller as a weight adjusted for the excess pressure. This is preferably also done with regard to the overpressure in the dispensing line. The result is that the adjusted bulk material weight is calculated with the aid of a current pressure prevailing in the storage container.
    A gravimetric metering device is preferably obtained in which the storage container and / or an output line for bulk material arranged after the output conveyor is provided with a pressure sensor which is designed to generate a signal for a pressure fluctuation during the refilling of the storage container, and wherein the controller is further designed to determine, from the signal for the pressure fluctuation and the signal from the scale, a value for the weight of the bulk material currently present in the storage container, adjusted for the pressure fluctuation.
    In the branch 42, the dynamic behavior of the gravimetric scales 11 is recorded in step with regard to the weight detected by them. The fact that the impulse caused by the refilled material over the spring stiffness of the scales 11 (it can be a single or several gravimetric scales, depending on the structure of the feeder 1), the damping of the weighing system and the entire weighed mass (weighed part the balance, the feeder, the bulk material and the force generated by the impulse on the balance) is set in vibration, a virtual force arises from the dynamic behavior of the oscillating balance, which represents a further disturbance, which is the detected weight of the bulk material in the storage container 4 falsified.
    The force generated by the pulse can be calculated according to step 45 in branch 40.
    The mass of the weighing part of the scales 11, the damping of the weighing system and its spring stiffness are parameters that a person skilled in the art can determine in a specific case because either the scales 11 are known, because these parameters can be determined via a calibration function or because the behavior of the balance can be determined through experiments simply by refilling. A person skilled in the art can use these parameters to calculate the oscillation and the resulting virtual force of the scales 11 during refilling and store them in the controller 10. The current weight signal is now adjusted with regard to the virtual force and stored as a weight adjusted for the dynamic behavior of the balance in the controller 10, after step 50. The result is that the adjusted bulk weight is calculated using the vibration properties of the at least one gravimetric balance The control of a gravimetric feeder is furthermore preferably designed to determine a bulk material weight in the storage container adjusted to a virtual force from the dynamic behavior of the at least one gravimetric scales oscillating due to the impulse of the bulk material falling into the storage container.
    It should be noted here that the influence of the dynamic behavior of the balance depends primarily on its spring stiffness - depending on the properties of the refilled material and the resonance frequency of the gravimetric balance, a person skilled in the art can, in a specific case, determine the dynamic behavior Refrain from adjusted weight, for example in the case of very rigid scales with a high resonance frequency and a material that swirls during refilling and generates a soft impulse.
    At this point it should also be mentioned that of course the disturbances according to branches 40 and 41 or the disturbances according to all branches 40 to 42 are recorded in parallel and a corrected weight of the bulk material in the storage container is obtained directly from the results of steps 45, 47 and if necessary 49 can be calculated.
    FIG. 4 shows a diagram 55 for the distribution of the bulk material between the refill container 3 and the storage container 4 during refilling. The time is plotted on the horizontal axis, where tB marks the beginning and t the end of the refill. The mass M of bulk material is plotted on the horizontal axis.
    The curve MN denotes the mass of bulk material in the refill container 3; it corresponds to the weight detected by the refill scales 14. The curve MV denotes the mass of bulk material in the storage container 4, it corresponds to its true weight.
    If the refill is released at the time tbau, the mass in the refill container is reduced immediately, since the bulk material falls through the connecting channel 7. During the falling time of the bulk material, however, the mass in the storage container does not change; it only increases at time tb + fall, namely when the falling bulk material has reached the lower level of the storage container. Thus, the mass in the storage container rises slightly for a short time after the end of the refill at time ten, namely until time te + fall. The second time interval Te = te - te + fall is smaller than the first time interval Tb = tb - tb + fall, since the height of fall at the upper level is smaller after refilling.
    The curve D denotes the difference between the masses in the refill container 3 and in the storage container 4, namely MN - MV. Since it is a matter of a mere exchange of mass between these containers, this difference should basically be constant and have the value Dk. The jump in curve D in the first time interval Tb to a value greater than Dk thus indicates that a bulk material is in free fall, also in the section TN and during the jump in the time interval Te.
    In step 34 of Figure 2, the controller 10 determines the actual mass flow output by the dispenser during refilling by forming the difference between the bulk weight output by the refill container 3 and the bulk material weight in the storage container 3, which has been cleared of faults, which is based on the the gravimetric scales 11 detected weight is based. According to diagram 55, the determined actual mass flow in the time interval Tb + TN + Te = te + Fall - tb contains systematic errors F = D - Dk. The calculation of the actual mass flow is thus too large by the error mass flow derived from time, which leads to a correspondingly incorrect correction factor. Depending on the specific case, this error can be accepted - however, the person skilled in the art will preferably modify the algorithm in step 34 of FIG. 2 so that the values for the mass output by the refill container 3 (curve MN) by one in the time interval The current time Tr can be shifted to the right, see chap. the curve MNr, with the result that the systematic error F is reduced or disappears. The time T is available from the detected weight of the refill scales 14 and the detected weight of the gravimetric scales 11 (rapid increase in weight due to the pulse) or can simply be assumed from the height of fall according to the geometry used in the specific case. Likewise the time Te.
    The result is that the refilled bulk material weight as the decrease in the weight of the refill container and the increase in the bulk material weight registered by the at least one gravimetric scale in the storage container for the calculation of the actual bulk material flow are processed at the same time or with a time difference, the time difference preferably being processed corresponds at least approximately to a fall time of the bulk material from the refill container into the storage container.
    Fig. 5 shows a flow chart of a further embodiment of the present invention. In a first section A, the metering device 1 (FIG. 1) is operated conventionally according to a volumetric control model during a first refill (step 30) and a first correction factor is then determined for the volumetric control model. In section B, for materials whose refill properties reproduce well in the specific case, the correction factor based on previous refills is further improved until the average of the actual mass flow output during refilling approaches or essentially corresponds to the target mass flow.
    In step 30 (section A) the first refilling begins, which according to step 60 only takes place with a volumetric control model. Nevertheless, according to the invention, in step 61 the mass of the refilled bulk material is determined via the refill scales 14 and stored in the controller 10. After refilling, the controller 10 switches the dosing device 1 back to the gravimetric mode, see FIG. Step 62.
    As soon as the scales have calmed down, the average actual mass flow output during refilling is determined according to step 63: in the gravimetric mode, the gravimetric actual mass flow output can now be reliably recognized, as can the true current weight of the bulk material Storage container 4. The difference between the refilled bulk material and the true weight at the beginning of the gravimetric mode gives the true mass of the bulk material dispensed during the refill, with the refill time the average refill actual mass flow during the refill. Since the conditions are known during the gravimetric operating mode (actual mass flow), the average refill actual mass flow up to the next refill can be calculated by the controller 10. In this way, according to the invention, the actual mass flow output during refilling is available, although only as an average value during refilling, but still as a quantitative value, which in a specific case can already satisfy quality assurance requirements in a production line.
    From the difference between the target mass flow rate and the average actual refill mass flow rate, the controller calculates a correction factor for the volumetric control model in step 64.
    The cycle is repeated in section B, but according to step 65 the volumetric control model corrected by the correction factor is used during the refilling. After the doser 1 has been operated again in gravimetric operation (step 67), the query is made as to whether operation should be continued (step 68), if not, the stop in step 69, if so, a renewed determination of the actual refill mass flow in step 70.
    The result is that the actual bulk material flow and / or the correction factor is determined after a refill, but before the subsequent refill and, in the case of the correction factor, is applied to the volumetric control model and for a next refill, the correction factor preferably being applied during several Refills are re-determined based on a previous correction factor, the control of the gravimetric dosing device further preferably being designed to determine a value for the weight of the total bulk material refilled during a refill from the signals of the sensor for the refill quantity and from a weight signal of the at least one gravimetric scales to determine an actual bulk material flow and / or a correction factor during the emptying of the storage container following the refill and, in the case of the specific correction factor, to apply this to the volumetric control model for a subsequent refill.
    According to the invention, further disruptions such as the additional compression or fluidization of the bulk material in the storage container generated by the pulse can be recognized and corrected. If there is additional compression, the actual mass flow becomes too large, if fluidization occurs, the actual mass flow becomes too small. In both cases this is recognized in step 34 of FIG. 2 and the mass flow is regulated accordingly in real time according to step 35. Likewise, in the sense of the average actual mass flow output, according to steps 63, 64 and 70 of FIG. 5.
    This also applies analogously to the case that bulk material is driven through the output conveyor by the impulse and as a result the actual mass flow briefly has an undesirable peak. The person skilled in the art can then design the control in such a way that a strong peak is recognized, the mass flow is regulated accordingly in real time or on average, and the time and height of the peak is also recorded and stored in the control. In addition to the correction factor, the volumetric control model can then contain a predetermined change which, at the established point in time, regulates the actual mass flow down in a predetermined manner. According to the invention, faults caused by bridge formation are also detected and eliminated during the construction of bridges, and also during the collapse of bridges, which triggers an impulse similar to the impulse of the refilled material.
    In FIG. 1, the mass of bulk material dispensed from the refill container 3 into the storage container 4 during the refill is detected via the one or more refill weighers 14, the refill weighers 14 representing sensors for a parameter for the refill amount output. Instead of the refill scales 14, the fill level of the refill container 3 can also be used, which can be detected by fill level sensors, provided that compression of the bulk material in the refill container is known, for example through experiments. Likewise, instead of a slide 15 (FIG. 1), the person skilled in the art can provide rotary valves for a fast but dosed discharge of the bulk material into the storage container 4. Finally, it is conceivable to provide a cascade of dispensers, with a refill dispenser being able to be designed according to FIG. 1, but then having a comparatively large conveying capacity. The delivery rate of the rotary valve or of the refill doser etc. then represents a parameter for the refill quantity output, which can be processed by the controller in a manner analogous to the weight signal of the refill scales 14.
    权利要求:
    Claims (20)
    [1]
    1. Method for determining the mass flow of a dosing device (1) for bulk goods, which has a storage container (4) and a refilling station (2) connected to it with a refilling container (3), the dosing device (1) having at least one gravimetric balance (11 ) for gravimetric dosing via an output conveyor, and the refill container (3) periodically refills the storage container (4) from a lower fill level to a filled state with bulk material and is provided with a sensor for a parameter for the refill quantity dispensed, and wherein during the refilling the output conveyor is controlled by a volumetric control model, characterized in that the bulk material weight refilled in this during the refilling of the storage container (4) from the data of the sensor for the refilling quantity dispensed from the refilling station and that during the refilling of the Storage container (4) there was an increase in Bulk weight is determined in the storage container (4) and the actual bulk flow output during refilling is calculated from the difference between these weights.
    [2]
    2. The method of claim 1, wherein a correction factor for the volumetric control model is further generated and applied to the control of the mass flow from the difference between a target - bulk material flow and the actual bulk material flow.
    [3]
    3. The method of claim 1 or 2, wherein during the refill at least once, preferably repeatedly, the actual bulk material flow is determined and / or the correction factor is generated, and wherein the correction factor determined in each case is applied in real time to the volumetric control model.
    [4]
    4. The method according to claim 3, wherein, the refilled bulk weight as a decrease in the weight of the refill container (3) and the at least one gravimetric scale (11) registered increase in bulk weight in the storage container (4) for the calculation of the actual bulk material flow simultaneously or are processed with a time difference, the time difference preferably corresponding at least approximately to a fall time of the bulk material from the refill container (3) into the storage container (4).
    [5]
    5. The method according to claim 3, wherein during the refill, the increase in the bulk weight in the storage container (4) is calculated via a bulk material weight cleaned of faults.
    [6]
    6. The method according to claim 5, wherein the adjusted bulk weight is calculated with the aid of a current pressure prevailing in the storage container (4).
    [7]
    7. The method according to claim 5, wherein the adjusted bulk weight is calculated with the aid of a pressure currently prevailing in the derivation (9).
    [8]
    8. The method according to claim 5, wherein during the refilling the adjusted bulk weight is calculated by the force exerted on the impulse of the falling bulk material on the storage container (4).
    [9]
    9. The method according to claim 5 or 8, wherein the cleaned bulk material weight is calculated via the vibration properties of the at least one gravimetric balance (11).
    [10]
    10. The method of claim 1 or 2, wherein the actual bulk material flow and / or the correction factor after a refill, but before the subsequent refill is determined and applied to the volumetric control model for a next refill, the correction factor preferably being based on several refills a previous correction factor is redetermined.
    [11]
    11. The method of claim 1 or 2, wherein the volumetric control model controls the mass flow generated by the output conveyor via a predetermined value for a target mass flow.
    [12]
    12. The method according to claim 1 or 2, wherein the volumetric control model additionally controls the mass flow generated by the output conveyor by data for the compression of the bulk material during the emptying of the storage container (4).
    [13]
    13. Gravimetric dosing device for bulk goods, with a storage container (4) for the bulk material to be dosed and a refill station (2) connected to this, which is designed to refill a refill quantity of bulk material into the storage container (4) and with a sensor for a parameter is provided for the refill quantity, with at least one gravimetric balance (11), which is operatively connected to the storage container (4) and an output conveyor for the bulk material for gravimetric metering of the bulk material, and with a controller (10) for the output conveyor , which is designed to control it during a refill phase according to a volumetric control model, characterized in that the control is further developed during the refill from the signals from the sensor for the refill quantity, the bulk material weight output by the refill station (2), and from the weight signal of the at least one gravimetric balance (11) to determine a value for the weight of the bulk material currently present in the storage container (4) and from this to determine an actual bulk material flow output by the metering device during refilling.
    [14]
    14. Gravimetric metering device according to claim 13, wherein the control is further developed to determine a correction factor for the volumetric control model from the difference between a desired bulk material flow and the actual bulk material flow and to apply it.
    [15]
    15. Gravimetric metering device according to claim 12 or 13, wherein the sensor for a parameter of the refill quantity is designed as a weight sensor (14).
    [16]
    16. Gravimetric metering device according to claim 12 or 13, wherein the storage container (4) and / or an output line (9) for bulk goods arranged after the output conveyor is provided with a pressure sensor (20, 21) which is designed during the refilling of the storage container (4) to generate a signal for a pressure fluctuation, and wherein the control (10) is further developed from the signal for the pressure fluctuation and the signal of the at least one gravimetric balance (11) a value for the weight adjusted for the pressure fluctuation to determine the bulk material currently present in the storage container (4).
    [17]
    17. Gravimetric metering device according to claim 12 or 13, wherein the controller (10) is designed to determine a pulse in the storage container (4), adjusted to the pulse of the bulk material falling into the storage container.
    [18]
    18. Gravimetric metering device according to claim 12 or 13, wherein the controller (10) is designed to correct a virtual force from the dynamic behavior of the oscillating at least one gravimetric balance (11) oscillating due to the pulse of the bulk material falling into the storage container (4) Determine the bulk weight in the storage container (4).
    [19]
    19. Gravimetric dosing device according to claim 12 or 13, wherein the controller (10) is further designed to determine the actual bulk material flow and / or the correction factor several times during the refilling and, in the case of the determined correction factor, to apply this in real time to the volumetric control model, in such a way that its value for the target bulk material flow is adjusted during the refilling.
    [20]
    20. Gravimetric dosing device according to claim 12 or 13, wherein the controller (10) is designed to determine from the signals of the sensor for a parameter for the dispensed refill quantity a value for the weight of the bulk goods refilled during refill and from a weight signal of at least to determine a gravimetric balance (11) during the emptying of the storage container (4) actual bulk material flow after the refilling and / or to determine a correction factor and, in the case of the determined correction factor, to apply this to the volumetric control model for a subsequent refilling.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    CH01064/18A|CH715304A2|2018-09-07|2018-09-07|Process for the gravimetric control of a dosing device for bulk goods during the refilling of its storage container and dosing device for carrying out the process.|CN201980073352.0A| CN113196019A|2018-09-07|2019-09-06|Method for the gravitational adjustment of a dosing device for pouring material during the refilling of its storage container and dosing device for carrying out the method|
    KR1020217010341A| KR20210069054A|2018-09-07|2019-09-06|Method of gravimetric control of a metering dispensing unit for bulk material in a storage hopper during refilling and a metering dispensing unit for carrying out said method|
    US17/190,591| US20210364340A1|2018-09-07|2019-09-06|Method for the Gravimetric Control of a Metering Device for a Bulk Material During the Refilling of its Storage Container, and Metering Device for Carrying Out the Method|
    EP19857130.9A| EP3847426A2|2018-09-07|2019-09-06|Method for the gravimetric control of a metering device for bulk material during the refilling of its storage container, and metering device for carrying out the method|
    PCT/IB2019/057521| WO2020049513A2|2018-09-07|2019-09-06|Method for the gravimetric control of a metering device for bulk material during the refilling of its storage container, and metering device for carrying out the method|
    JP2021512736A| JP2021536010A|2018-09-07|2019-09-06|A method for controlling the weight of the weighing and distributing unit for bulk materials during refilling of the storage hopper and the weighing and distributing unit for carrying out the above method.|
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