• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a device (1) for measuring a pressure, in particular a pitot tube, comprising a tube (2) having a first opening (3) and a first pressure measuring device (4) for determining a pressure acting on the first opening (3). In order to avoid a blockage of the tube (2) and at the same time to allow an uninterrupted measurement, the invention provides that a conveying device, in particular a pump, is provided in order to move the medium in the tube (2) to the first opening (3). to produce decreasing pressure, the device (1) being designed such that when the tube (2) is filled with a medium to which a pressure decreasing towards the first opening (3) acts, with the first pressure measuring device (4) a pressure acting on the first opening (3) can be measured indirectly via the medium. Furthermore, the invention relates to a method for measuring a pressure with a device (1) which has a tube (2) with a first opening (3) and a first pressure measuring device (4).
    公开号:AT516021A4
    申请号:T50469/2014
    申请日:2014-07-04
    公开日:2016-02-15
    发明作者:
    申请人:Ebelsberger Karl Ing；
    IPC主号:
    专利说明:

    Apparatus and method for measuring a pressure
    The invention relates to a device for measuring a pressure, in particular a pitot tube, comprising a tube with a first opening and a first pressure measuring device for determining a pressure acting on the first opening.
    Furthermore, the invention relates to a use of such a device.
    Moreover, the invention relates to a method of measuring a pressure with a device having a tube with a first opening and a first pressure measuring device.
    Various devices for pressure measurement have become known from the prior art. Devices with a flow-oriented tube with an opening, so-called pitot tubes, usually serve to measure a dynamic pressure or total pressure in the flow. Simultaneous measurement of total pressure and static pressure allows determination of a velocity of flow, which is why pitot tubes are used on airplanes for speed measurement. In this case, the pitot tube is arranged on an outside of the aircraft such that during a flight the flow hits the opening of the tube substantially frontally in order to measure the back pressure. To measure the static pressure, a second opening connected to a pressure sensor, which is often aligned perpendicular to the first opening, may be provided in addition to a first opening, so that the flow is approximately parallel to a plane of the second opening. Such a second opening is also called static port.
    It has been found that in such devices, in particular the frontal flow-orifice is often clogged by particles, freezing rain, undercooled water, contaminants and the like, which makes measurement of the impact pressure and the speed of the aircraft no longer possible.
    To prevent freezing of the pitot tube at high airspeeds and low temperatures at high altitudes, prior art pitot tubes are often equipped with heaters. Furthermore, document WO 2013/0282200 A1 discloses a device for arranging in the opening in order to prevent the penetration of contaminants into a pitot tube. Document DE 10 2012 209 352 A1 has disclosed an apparatus for cleaning and removing particles blocking the pitot tube. For this purpose, in a blockage, a piston or the like is moved through the end opening of the pitot tube, however, cleaning of the pitot tube requires interruption of the velocity measurement.
    A disadvantage of the devices of the prior art is that a blocking of the tube can not be reliably prevented, whereby it comes again and again to precipitates the speed measurement of aircraft. This is particularly unfavorable because in poor visibility conditions pilots rely entirely on reliable data from aircraft measurement instruments and many decisions are made in extreme situations based on a measured speed. Thus, failure of the speed measurement, even at high altitudes for even a few minutes, can cause a plane crash. Due to flight data recorder evaluations, several aircraft crashes of the recent past are attributed to a velocity measurement falsified by a blocked pitot tube. A temporary failure of the speed measurement, for example for cleaning the pitot tube, must therefore be avoided in any case.
    This is where the invention starts. The object of the invention is to provide a device of the type mentioned above, with which a reliable and uninterrupted measurement of a pressure is possible by blocking the tube is prevented.
    Furthermore, a method of the type mentioned for continuous pressure measurement is to be given.
    The first object is achieved according to the invention by a device of the type mentioned above, wherein a conveyor, in particular a pump, is provided to produce in a medium located in the pipe a decreasing pressure to the first opening, wherein the device is designed such that when the pipe is filled with a medium, on which a pressure decreasing toward the first opening acts, with the first pressure measuring device, a pressure acting on the first opening is indirectly measurable via the medium.
    The device according to the invention makes it possible to measure the pressure, whereby a clogging of the usually cylindrical and rigid tube is easily prevented by continuously transporting a medium through the first opening, since unlike pitot tubes of the prior art a pressure can be provided by means of the conveyor in the pitot tube which is higher than the dynamic pressure acting on the first opening.
    A resulting pressure difference between pressure in the pipe, which is measured with the first pressure measuring device usually designed as a pressure transmitter, and ambient pressure or dynamic pressure acting on the first opening thus leads to a transport of the medium out of the pipe through the first opening. Thereby, particles, ice grains and the like impinging on and blocking the first opening are immediately removed from the medium. In the context of the invention, it has been recognized that a dynamic pressure acting on the first opening can also be measured inside the tube because the medium transmits the dynamic pressure at the first opening to the first pressure measuring device, so that it differs from prior art devices at the same time a pressure measurement and a cleaning of the first opening are possible. This makes an interruption-free measurement possible. The first opening means an interface between an interior of the pipe and an environment on which the dynamic pressure substantially acts. A static pressure applied to the medium by the conveyor is thus largely, normally completely, degraded at the first opening. The medium generally has only one dynamic pressure resulting from an exit velocity, also referred to as the acceleration amount, when exiting the opening from an environment. Usually, the opening is formed as a bore.
    It is understood that the pressure in the pipe indirectly measured via the medium is higher than the pressure applied to the first opening. A conversion of measured pressure of the medium in the pipe to that at the first opening adjacent
    Pressure or dynamic pressure, however, is possible in a simple manner. For example, pressure loss between measuring position in the tube and first port can be determined computationally or empirically, for example by pressure loss determination experiments, for certain flow conditions, so optionally depending on various factors such as viscosity, temperature and velocity, unambiguous assignability of measured pressure of the medium in the tube to back pressure at the first port is present. It will be understood that a rate at which the medium flows out of the tube at the first port also has to be taken into account when converting measured pressure to back pressure, although an influence thereof on the pressure loss is usually of lesser importance. In addition to a pipeline pressure loss, a geodetic height difference between first port and first pressure gauge, additional inertia resulting from inertial forces, and the back pressure, also the acceleration altitude related to the exit velocity across the medium to the pressure measured by the first pressure gauge.
    In principle, any device with which a pressure decreasing towards the first opening can be applied to a medium located in the tube or with which a defined delivery rate of a medium can be reached through the first opening from the tube can be used as conveying device. For example, the conveyor may be formed by a pressurized reservoir which is connected to the pipe via a particular pressure reducing valve. The conveyor thus acts on the tube and is connected to the tube so that a medium can be transported by the conveyor into the tube and moved out of the tube through the first opening. Usually with the conveyor, a medium can be supplied to the tube at an end opposite the first opening.
    As a rule, a static pressure in the medium decreases from the conveyor to the first opening, whereby a movement in the medium is achieved. For this purpose, the conveying device and the device are usually matched to one another such that with the conveying device over a defined pressure range at least the amount of medium which leaves the tube through the first opening due to the pressure difference can be supplied to the tube. It is understood that, for example, with a smaller first opening, a lower delivery rate of the conveyor is required to maintain a filling of the tube or a desired pressure differential between an interior of the tube and an exterior of the tube and a back pressure of the environment, respectively.
    A particularly accurate determination of the pressure is at the same time robust execution possible if the conveyor is designed as a pump, in particular as a gear pump. Gear pumps have been proven to achieve a particularly well defined delivery rate and to provide a sufficiently large pressure differential. A constant flow rate results in a particularly well-defined pressure difference or pressure drop between pressure at the pressure transmitter and at the first opening adjacent ram pressure, so that a particularly accurate indirect pressure measurement over the medium is possible. In this case, the back pressure at the first opening is determined by subtracting the defined pressure difference from the pressure measured by the first pressure measuring device.
    The first pressure measuring device may for example be a pressure sensor, in particular a piezoelectric sensor, which projects into the tube or into a volume connected to the interior of the tube, which is filled with the medium, if an additional pressure is applied to the medium in the tube by the conveying device.
    In a particularly simple embodiment, the first pressure measuring device can also comprise or be formed by a sensor of the conveyor, since a power consumption of the conveyor remains constant, ie a constant mass flow conveyed through the first opening out of the pipe, depending on a pressure difference. which is to be overcome in the promotion of the medium. A constant or constant flow rate can be achieved for example with a constant-speed driven gear pump and a liquid medium.
    Alternatively or additionally, a flow rate can be measured to determine the pressure, even with known or constant power consumption of the conveyor, since this decreases with constant power consumption with increasing by the conveyor to be bridged pressure difference. The first pressure measuring device may therefore also comprise or consist of a flow meter. It is advantageous if a pressure from an area, by means of which the conveyor removes the medium, for example an environment or a reservoir, is known, since then performance data of the conveyor can be used to close the pressure applied to the first opening.
    The medium may in principle be any medium that can be conveyed through the tube and allow removal of the first opening blocking particles and the like. Usually, a liquid or gaseous medium is used, since such a medium can be conveyed with low resistance. In particular, when air is used as a medium, an additional reservoir for the medium can be omitted and ambient air can be conveyed.
    Accurate pressure measurement becomes easily possible when a portion of the pipe between the first pressure measuring device and the conveyor is completely filled with a medium. Thereby, a pressure from the conveyor to the first pressure measuring device can be transmitted via the medium. In addition, because the medium acts on the medium by a pressure acting through the first opening into an interior of the tube, the pressure medium bar acting on the first opening can be measured with the first pressure measuring device. As a rule, the tube is completely filled with a medium conveyed by the conveyor, so that the medium exits the tube continuously at the first opening.
    In order to achieve a measurement result with high accuracy, it is normally provided that with the first pressure measuring device, a pressure in the medium in a region between the conveyor and the first opening is measurable. For this purpose, the first pressure measuring device is preferably arranged along a direction of flow of the medium between the conveying device and the first opening, so that the measurement result is not distorted by local and optionally discontinuous flows.
    Measuring a pressure is basically possible with the device even if a compressible medium such as a gas, for example air, is used. to
    Achieving a high measurement accuracy, it has proven to be favorable that the medium is a liquid, in particular an antifreeze liquid. Freezing of the first opening can thus be avoided even at very low temperatures and high flight speeds in a particularly simple manner. A specific choice of antifreeze liquid will result depending on an expected service temperature. Using the apparatus for measuring speed on an aircraft with a deployment altitude in excess of 10,000 m, an antifreeze fluid having a freezing point of less than minus 60 ° C, in particular isopropanol, has been found. Typically, the apparatus includes data acquisition means for continuously acquiring data measured by the first pressure measuring device. Thereby, a blockage of the first opening can be easily determined by an over-limit pressure rise in the line. In particular, when a liquid is employed as the medium, blockage of the first opening can be detected in a particularly rapid manner, usually within a few milliseconds, usually within a few microseconds, by a pressure rise within a short time in the tube. A blockage of the first opening thus detected may be used, for example, to indicate a failure of a speed measurement for which the dynamic pressure is being measured. Thus, when used in an aircraft, there is a risk of making decisions based on incorrect measurements. To determine the threshold above which a pressure change is interpreted as a blockage of the first port, a pressure change can be calculated or measured at maximum expected speed differences in a flow. Using the device on an aircraft with a liquid as the medium, a pressure change of more than 0.38 bar / s, which may also be referred to as a pressure increase gradient, has been pointed out as an indication of a sudden blockage of the tube. This corresponds to a speed change of 200 km / h within 0.131 seconds, which is possible for example when flying from one air layer with 100 km / h backwind into another air layer with 100 km / h headwind.
    It has proven to be advantageous that the conveyor is connected on the one hand to the pipe and, on the other hand, to a reservoir. The reservoir can thus be filled, for example, before a flight with a medium such as an antifreeze liquid, which during an operation, for example during a flight using the
    Apparatus for measuring speed on an aircraft, by means of which the conveyor device for a dynamic pressure measurement is conveyed through the pipe and the first opening. Usually, the reservoir has a vent valve. The vent valve may be designed so that a static pressure of a flow flowing around the device in the reservoir is applied. An output of the conveyor then increases with increasing velocity or pressure, against which the conveyor conveys the medium through the tube and the first opening. It may also be provided that a constant or defined pressure is provided via the vent valve in the reservoir.
    Advantageously, during a measurement, a continuous delivery of the medium through the tube and the first opening are opposite to a flow direction of a medium flowing around the tube, the velocity of which is measured. For example, if the device is being moved by aircraft, it will be conveyed in the direction in which the device is being moved, but with a speed that is higher than that of the device, when used on an aircraft, ie in the direction of flight. In order to minimize consumption of the medium, it is generally provided that the device is designed in such a way that only a small amount of the medium is conveyed during a pressure measurement. This can be achieved on the one hand in that a pressure of the medium in the tube is only slightly above a pressure acting on the first port, since a speed at which the medium flows through the first opening from the tube, in particular by a pressure difference between pressure on the conveyor and the first opening adjacent pressure and a pressure drop in the tube is determined. On the other hand, a low consumption of the medium can also be achieved by the tube having an inner diameter which decreases towards the first opening. Typically, an inner diameter of the tube in the tube is about 3 mm for ease of manufacture and reduces to about 0.1 mm in the region of the tube tip. Methods for producing correspondingly small holes are known. For a particularly low consumption of the medium, it has proved to be favorable if a minimum diameter of the tube is less than 20 mm, advantageously less than 5 mm, preferably less than 1 mm, preferably less than 0.5 mm, in particular 0.01 mm to 0.2 mm. Furthermore, this also makes it possible to use a conveyor with low power in order to obtain a continuous overpressure in the pipe. Usually, the tube has the minimum diameter in the area of the first opening. Preferably, the first opening is formed with the minimum diameter. This achieves low power consumption of the device. In addition to a low consumption of the medium, such a formation also prevents in a simple way that large foreign bodies can penetrate into an interior of the tube.
    For accurate speed measurement, it is favorable if the tube has an outer diameter tapering towards the first opening. Usually, a tube tip of the tube is approximately conical. As a result, influences of a flow in the region of the first opening are largely avoided, whereby a favorable approach angle independence is achieved. Preferably, the tube has a cylindrical cross section. It is understood, however, that the tube can in principle also be formed with a, for example, rectangular or elliptical cross-section.
    The device can also be used to determine a velocity profile in a flow. For this purpose it can be provided that a plurality of devices according to the invention are distributed in the flow such that a velocity profile of the flow, ie a spatial velocity distribution, can be measured by means of the devices.
    In order to be able to measure a static pressure with the device, not only a dynamic pressure but also for speed measurement, it is advantageous if the device has a static line with a second opening and a second pressure measuring device for determining a pressure acting on the second opening, the second opening in one plane other than the first opening, in particular in a plane approximately perpendicular to a plane of the first opening. Both openings usually protrude into a medium whose speed is to be measured. Thus, a flow in which the device is positioned acts only on an opening or impact on the first opening only, while with the second opening a static pressure can be measured via the static line. It goes without saying that, to measure the second pressure, only a second pressure measuring device can be provided, with which a static pressure in a flow flowing around the device can be measured, for example a pressure sensor which is oriented parallel to the flow, preferably a piezoelectric sensor.
    In order to prevent freezing or clogging of the static line, a conveying device, in particular a pump, is advantageously provided to produce a pressure decreasing towards the second opening in a medium located in the static line, the device being designed such that when the static line is connected to a medium is filled, on which a decreasing to the second opening pressure acts, with the second pressure measuring device acting on the second opening Druckmittelbar over the medium is measurable. Analogous to the indirect determination of the pressure acting on the first opening, the pressure in the static line measured in the medium must also be converted to a static pressure acting on the second opening. An assignment of measured pressure in the static line and at the second opening adjacent pressure can again empirically or computationally respectively. Separate conveyors and pressure gauges may be provided for the pipe and the static line. However, it is also possible that a single conveyor applies pressure to a medium in the tube and pressure to a medium in the static line. Also, a single pressure measuring device may be provided for measuring the pressure in the static pipe and in the pipe. The first pressure-measuring device corresponds in the case of the second pressure-measuring device.
    In order to measure a velocity of a flow flowing around the device with the tube and the static line, it is normally provided that the device is designed to measure a differential pressure between the first pressure and the second pressure. This can be done, for example, by a membrane, on which, on the one hand, a pressure acting on the tube and on the other hand, a pressure acting on the static line acts when a deflection of the membrane caused by a pressure difference is measured. The deflection is then proportional to a differential pressure between back pressure and static pressure or a speed.
    Alternatively or additionally, it can be provided that a second pressure measuring device is provided for measuring a pressure in the static line. In order to determine a speed, in this embodiment a difference between pressure determined at the first opening and pressure determined at the second opening is calculated. In this embodiment, in addition to the pressure difference, static pressure and static pressure exist in absolute values.
    A structurally simple embodiment results when a manifold is provided, on which acts the conveyor, wherein the manifold is connected to the pipe and / or to the static line via switchable valves. As a result, an additional conveying device for the static line can easily be dispensed with. The back pressure and the static pressure can then be measured simultaneously or alternately by means of the valves.
    It has proven to be advantageous that an acting on the tube, preferably switchable pressure accumulator is provided. Due to the pressure accumulator occurring pressure peaks can be buffered or intercepted when an intrusion of ice grains or the like, so that damage due to an excessively high pressure on the device are avoided.
    The advantages of the device can be implemented particularly well when the device is used to determine a speed. Due to the robust method that can be implemented with the device, it is possible to use objects that are stationary as well as moving in a flow, such as land, water or air vehicles. More preferably, the device is used to measure a dynamic pressure in a velocity measurement, wherein a static pressure measurement is also carried out to determine the speed from a difference between static pressure and dynamic pressure.
    In principle, the speed measuring device can be used in any flow. It has proven to be particularly favorable if, in the case of an aircraft having a speed-measuring device for determining a speed while measuring a back pressure, the speed-measuring device has a device according to the invention. Typically, the pitot tube disposed on the outside of the aircraft is designed in accordance with the invention so that a speed of the aircraft is possible while transporting a medium through the first opening. As a result, blocking of a pitot tube commonly used on airplanes for speed measurement can be prevented in a simple manner while still ensuring reliable speed measurement. In particular, to avoid freezing of the first opening, it has proven useful when using the device on an aircraft that an antifreeze liquid is used as the medium ,
    For measuring an airspeed of an aircraft, it is advantageous that the tube is oriented in the direction of flight and connected by a console to the aircraft fuselage. It is usually envisaged that the console is aligned perpendicular to the oriented in the direction of the pipe and connected at a rear end of the tube with the pipe and the fuselage. This results in an approximately L-shaped configuration of a part of the device lying outside the aircraft fuselage.
    It has been shown that ice crystals attach themselves to the console under appropriate weather conditions, which can also form thick deposits of ice. In order to prevent such ice deposits from protruding into a region of a tip of the tube and thus plugging the first opening, it is preferably provided that a distance from the bracket to the first opening be 5 cm to 30 cm, in particular 10 cm to 20 cm, preferably approximately 12 cm 15 cm, is.
    The further object is achieved according to the invention by a method of the type mentioned above, wherein a pressure acting on the first opening with the first pressure measuring means is measured indirectly via a medium located in the tube, which conveyed by a conveyor, in particular a pump, through the first opening from the tube becomes. As a result, clogging of the tube is easily prevented, whereby a reliable speed measurement can be ensured. Usually, the method is implemented with a device according to the invention.
    It is particularly favorable if the medium is conveyed continuously through the first opening during a measurement of the pressure, preferably at a speed of less than 50 km / h, advantageously 1 m / h to 50 m / h, advantageously 5 m / h to 20 m / h, in particular 10 m / h to 15 m / h. This allows simultaneous discharge of contaminants and measurement of a velocity. A continuous and with constant speed promotion has the further advantage that for an indirect pressure measurement favorable, stable conditions in the tube vorhanden.Aufgrund the relatively low speed with which the medium is discharged through the first opening, resulting in correspondingly small diameter of the first opening , normally less than 1 mm, a low consumption of the medium of, for example, about 0.0015 ml / min. However, depending on the weather, it may also be beneficial to transport a higher amount through the orifice by means of the conventional positive-conveying pump. For example, for first de-icing, an antifreeze fluid level of 0.374 ml / min or more may be transported through the first port. In general, a control is provided, with which the amount is regulated depending on the weather conditions such that at low consumption of antifreeze liquid icing of the first opening is reliably prevented.
    A pressure required to achieve such speeds or a capacity of the conveyor results from further parameters such as a pressure loss in the pipe and an expected pressure difference between an area where the conveyor conveys the medium and a first opening. To remove particles blocking the first opening, the conveyor may also be designed to apply a greater pressure, for example to apply a pressure of 1 bar to 100 bar, in particular 5 bar to 30 bar, to a medium in the tube. Usually, as the material for the tube in metal, preferably titanium, used, so that despite a high pressure in the tube allowable strength limits are not exceeded.
    As a rule, during the measurement, the tube is completely filled with the medium on which, on the one hand, a pressure acting on the first opening and, on the other hand, a pressure applied by the conveyor act. By such, usually homogeneous filling of the tube with a single medium, a particularly good transfer of the pressure acting on the first opening pressure on the first pressure measuring device is ensured.
    It is advantageously provided that the medium is a liquid, in particular an antifreeze liquid. A choice of a specific antifreeze liquid results depending on the specific requirements, which include, inter alia, a
    Flow rate and a temperature of the device flowing around the medium.
    In a method for measuring a velocity, wherein a dynamic pressure and static pressure are measured, it has been proven that the back pressure is measured by a method according to the invention. Thereby, a failure of the speed measurement by a blockage of the first opening can be easily prevented.
    Further features, advantages and effects of the invention will become apparent from the following examples. In the drawings, which are referred to, show:
    Figures 1 to 3 an aircraft equipped with a device according to the invention in different views.
    4 shows a detail of a device according to the invention;
    Fig. 5 and 6 details of further inventive devices.
    Fig. 1 shows schematically an aircraft 11 formed with a device 1 according to the invention. As can be seen, the apparatus 1 comprises a tube 2 oriented in the direction of flight 22 with a first opening 3 located at the end on a tube axis, which is connected to a conveyor device designed as a gear pump 5 and via a collecting line 8 to a first pressure measuring device 4 designed as a pressure transmitter. Further, a static line 17 is provided with a second opening 15, wherein the second opening 15 lies in a plane which is perpendicular to a plane in which the first opening 3 of the tube 2 is located.
    As a result, a dynamic pressure acts on the first opening 3 and static pressure on the second opening 15, so that a speed of the flow can be determined by subtraction. The tube 2 and the static line 17 are connected to a manifold 8, which is connected via the conveyor to a reservoir 6, in which an antifreeze liquid 24 is stored as a medium.
    In order to prevent that when removing the antifreeze liquid 24 from the reservoir 6 in the reservoir 6 forms a suppression, the reservoir 6 has a loading and
    Bleed valve 13 on. Further, a fine filter 21 is provided between the reservoir 6 and the gear pump 5 so that impurities from the reservoir 6 can not enter the pipe 2. Apart from the gear pump 5, a pressure accumulator 10 acts on the collecting line 8 in order to be able to intercept the pressure peaks occurring when particles, raindrops and the like penetrate.
    A connection of the manifold 8 to the pipe 2 and the manifold 8 as shown via switchable valves 9. Thus, the antifreeze liquid 24 alternately or simultaneously through the pipe 2 and the static line 17 are promoted to allow a pressure measurement over the antifreeze liquid 24 during cleaning. As a result, it is possible, for example, to check easily before starting whether the first opening 3 and / or the second opening 15 are clogged or taped with an adhesive tape. During a flight, the second port 15 typically does not continuously, but only occasionally, normally at regular intervals, convey a medium to check for possible blockage, since a blockage risk at the second port 15 is substantially less than due to an orientation thereof about parallel to the flow the first opening 3. The device 1 can also be used for measuring the speed, when both valves 9 are opened, so that the manifold 8 is connected both to the pipe 2 and to the manifold 8. The jam pressure is measured indirectly via the first pressure measuring device 4 which is connected to the manifold 8, while a static pressure is measured via a second pressure measuring device 4a connected to the second line and also designed as a pressure transmitter. It is understood that a measurement of a pressure can also be carried out indirectly via a measurement of a speed with which the medium or antifreeze liquid 24 flows through the tube 2 and the static line 17, respectively. Usually, a pressure in the tube 2 is measured continuously, for example by means of a data processing system such as a computer. Thereby, even a blockage of the pipe 2 by intrusion of a hailstone, a particle or the like can be directly detected since a blockage of the first opening 3 while simultaneously conveying the gear pump 5 results in an extreme pressure increase within a short time. About this pressure increase within a short time, also softer than
    Thus, a blockage can be easily determined if the pressure increase gradient is above a defined limit. It has been found that a pressure increase gradient of more than 0.38 bar / s indicates a blockage of the first opening 3. In the event of a blockage, a pressure in the tube 2 may also rise to about 280 bar. A reflux of the antifreeze liquid 24 into the reservoir 6 is prevented by a between the conveyor and the first opening 3 and between the conveyor and the second opening 15 arranged check valve 20 in a simple manner.
    Since, in contrast to conventional pitot tubes in aircraft 11 in a device 1 according to the invention, a fluid which is conveyed continuously as a rule is used as the medium, mass forces of the fluid acting on pressure-measuring devices 4, 4 can generally not be neglected. However, a computational correction of a measurement result by mass forces, which act on the antifreeze liquid 24 and thus on pressure measuring devices 4, 4a, is possible without further ado. For this purpose, it can preferably be provided that acceleration sensors are arranged in the region of the device 1 on the aircraft 11 in order to be able to take into account mass forces particularly precisely. Furthermore, it is understood that the pressures measured in the pipe 2 or in the static line 17 with the pressure measuring devices 4, 4a do not exactly correspond to the back pressure and the static pressure, but the measurement results in particular by a pressure loss between a measuring position and first opening 3 and second opening 15 Conversion of measured pressure accumulation pressure or static pressure can be done based on a line calculation or based on calibration measurements of known flow velocity. Unlike pitot tubes of the prior art, a drainage hole in the tube is usually not provided to reliably transmit a pressure from the first opening 3 to the first pressure gauge 4.
    Further, it can be seen in Fig. 1 that the tube 2 is connected via a bracket 14 to an aircraft fuselage, whereby the tube 2 is spaced from an aircraft fuselage wall 12. In order to prevent a layer of ice growing on the console 14 during flight from blocking the first opening 3, a distance 16 of the first opening 3 from the console 14 of usually more than 5 cm, in particular 10 cm to 12 cm, is provided. Further, the tube 2 may be provided with a so-called anti-ice coating and arranged in the tube 2 for external deicing of the tube 2, a heater.
    Fig. 2 shows a side view of an aircraft 11 with a device 1 according to the invention for measuring a speed. As shown, the apparatus 1 is disposed in a front portion of the aircraft 11, with the first pressure gauge 4 positioned in the tube 2 between the conveyor and the first opening 3. In the case of an illustrated ascent flight of the aircraft 11, the first opening 3 is lower by an additional amount than the first pressure measuring device 4 provided for measuring a pressure applied to the first opening 3, so that a corresponding height difference or resulting hydraulic forces are indirectly determined at the first opening 3 applied pressure must be taken into account. Due to known constructional dimensions of the device 1 as well as a measurement of an inclination of the aircraft 11, this is readily possible when converting measured pressure to pressure applied to the first port 3.
    Fig. 3 shows schematically the aircraft 11 formed with a device 1 according to the invention from a tail in the direction of flight, wherein wings 23 of the aircraft 11 are shown. The aircraft 11 is shown inclined to fly through a left turn. Mass forces acting on the antifreeze fluid 24 are typically computed by measuring accelerations acting on the aircraft 11 in all directions and using the measured accelerations to account for inertial forces. Here, too, results due to a lateral inclination of the aircraft 11, an additional difference in height between the first pressure measuring device 4 and the first opening 3, which is taken into account in determining the voltage applied to the first opening 3 pressure. The same applies to a height difference between the second pressure measuring device 4a and the second opening 15.
    4 shows a tube tip 7 of a tube 2 of a device 1 according to the invention.
    As shown, the tube 2 is formed with an outer diameter decreasing to the tip, so that an approximately conical tube tip 7 is formed. It is understood that the tube tip may alternatively also be cuboidal, hemispherical or halbellipsoidförmig trained. Accurate measurement is possible if, in the region of the first opening 3, a ratio of the outer diameter of the tube 2 to the inner diameter or inner diameter of the tube 2 is obtained. to a diameter of the first opening 3 is only slightly larger than one. The illustrated tube tip 7 has an outer diameter of 0.5 mm at the first opening 3, so that a ratio of outer diameter to inner diameter at the first opening 3 is five. As a rule, the tube tip 7 has a cone angle of about 30 °. As a result, a falsification of a flow in the region of the tip is avoided, so that the dynamic pressure measured in the region of the first opening 3 substantially corresponds to the actual back pressure.
    Further, it can be seen that an inner diameter of the tube 2 is formed decreasing towards the tip, the first opening 3 having a diameter of only 0.1 mm in order to easily prevent large particles from entering. Furthermore, it is ensured that only a small amount of the antifreeze liquid 24 is required to carry out the method, wherein the antifreeze liquid 24 is continuously discharged through the first opening 3. In a region more than about 8 mm apart from the first opening 3, the tube 2 has an inner diameter of about 3 mm.
    A particularly low consumption is achieved when the antifreeze liquid 24 is conveyed through the pipe 2 and the first opening 3 at a low speed. Optimal speed results from the preferred requirement that at least the amount of antifreeze liquid 24 is conveyed which is the first Opening 3 evaporates. For conventional antifreeze liquids 24, this results in a speed at the first opening of 1 m / h to 50 m / h, in particular 10 m / h to 20 m / h. Isopropanol is advantageously used as antifreeze liquid since this antifreeze liquid 24 is suitable for flight altitudes of more than 10,000 m and corresponding speeds because of a very low freezing point. In particularly unfavorable weather conditions, such as heavy rainfall at particularly low temperature, a promotion of the antifreeze liquid 24 can also be carried out at a significantly higher speed, for example, up to 50 km / h through the first opening 3, to ensure high availability.
    FIG. 5 shows an alternative embodiment of a tube tip 7 of a device 1 according to the invention from the front, that is to say from a direction from which a flow impinges on the tube tip 7. As can be seen, the first opening 3 is not formed with a circular diameter, but in the form of a cross. The cross is thereby formed by two intersecting slots 19 having a width of about 0.1 mm. The slots 19 have a length of about 3 mm. At the same time, a jam pressure can be measured with high accuracy even with slightly varying flow angles. At the same time, low consumption of a medium is ensured and penetration of particles with a diameter of more than 0.1 mm is prevented.
    6 shows in a front view another alternative embodiment of a tube tip 7 of a tube 2 of a device 1 according to the invention. In this embodiment, the first opening 3 is formed by a plurality of bores 18 of approximately circular cross-section, each individual bore 18 having a diameter of approximately 0.1 mm.
    With a device 1 according to the invention, a measurement of a back pressure is continuously possible, at the same time a penetration of foreign bodies in the tube 2bzw. a blockage of the tube 2 is avoided by foreign bodies or ice. By forming the device 1 with an additional device for measuring a static pressure, which is preferably also formed with a pressurized medium, a reliable speed measurement can take place. Thus, by using the apparatus 1 on an airplane 11, failure of the speed measurement can be easily and reliably prevented, thereby enhancing safety. Usually, an antifreeze liquid 24 is continuously discharged through the pipe 2, for example a pitot tube of an aircraft 11, against the flow direction out of the pitot tube through the first opening 3. In this case, the medium serves on the one hand a discharge of foreign bodies in the tube 2 and on the other hand, a transmission of the dynamic pressure, so that due to a pressure measured in the tube 2 of the first medium and a known pressure, which is applied by the conveyor to the medium, the back pressure at the first opening becomes. Therefore, if particles penetrate through the first opening 3 in the tube 2, they are decelerated by the usually continuously promoted antifreeze liquid 24, accelerated in the opposite direction and discharged from the tube 2. An ejection of the particles can then take place with a maximum of the conveyor pressure achievable. This results in low penetration depths of the particles of usually less than 1 mm, whereby the tube 2 is rinsed again in a few milliseconds upon penetration of particles. This ensures high availability.
    权利要求:
    Claims (20)
    [1]
    A device (1) for measuring a pressure, in particular a pitot tube, comprisinga tube (2) having a first opening (3) and a first pressure measuring device (4) for determining a pressure acting on the first opening (3), characterized in that a conveyor, in particular a pump, is provided for producing a pressure decreasing in a tube (2) towards the first opening (3), the device (1) being designed such that when the tube (2) is in contact with a medium is filled, on which a to the first opening (3) towards decreasing pressure acts, with the first pressure measuring means (4) acting on the first opening (3) pressure is indirectly measurable via the medium.
    [2]
    A device (1) according to claim 1, characterized in that a portion of the tube (2) between the first pressure measuring device (4) and the conveyor is completely filled with a medium.
    [3]
    3. Device (1) according to claim 1 or 2, characterized in that with the first pressure measuring device (4), a pressure in the medium in a region between the conveyor and the first opening (3) is measurable.
    [4]
    4. Device (1) according to one of claims 1 to 3, characterized in that the medium is a liquid, in particular an antifreeze liquid (24).
    [5]
    Device (1) according to any one of Claims 1 to 4, characterized in that the conveyor is connected on one side to the tube (2) and on the other side to a reservoir (6).
    [6]
    A device (1) according to any one of claims 1 to 5, characterized in that the tube (2) has an inner diameter which decreases towards the first opening (3).
    [7]
    A device (1) according to any one of claims 1 to 6, characterized in that a minimum diameter of the tube (2) is less than 20 mm, advantageously less than 5 mm, preferably less than 1 mm, preferably less than 0.5 mm , in particular 0.01 mm to 0.2 mm.
    [8]
    A device (1) according to any one of claims 1 to 7, characterized in that the tube (2) has an outer diameter tapering towards the first opening (3).
    [9]
    A device (1) according to any one of claims 1 to 8, characterized in that the device (1) comprises a static line (17) having a second opening (15) and a second pressure measuring device (4a) for determining a second opening (15). wherein the second opening (15) lies in a plane different from the first opening (3), in particular in a plane approximately perpendicular to a plane of the first opening (3).
    [10]
    Device (1) according to claim 9, characterized in that a conveying device, in particular a pump, is provided for producing a pressure decreasing towards the second opening (15) in a medium located in the static line (17), the device (1) is designed such that when the static line (17) is filled with a medium to which a pressure decreasing towards the second opening (15) acts, the second pressure measuring device (4a) can measure a pressure acting on the second opening (15) indirectly via the medium is.
    [11]
    Device (1) according to claim 9 or 10, characterized in that the device (1) is designed to measure a differential pressure between the first pressure and the second pressure.
    [12]
    12. Device (1) according to one of claims 1 to 11, characterized in that on the pipe (2) acting, preferably switchable pressure accumulator (10) is provided.
    [13]
    Aircraft (11) having a speed measuring device for determining a speed while measuring a back pressure, characterized in that the speed measuring device comprises a device (1) according to one of claims 1 to 12.
    [14]
    Aircraft (11) according to claim 13, characterized in that the tube (2) is oriented in the direction of flight (22) and connected to the fuselage by a bracket (14).
    [15]
    Use of a device (1) according to any one of claims 1 to 12 for determining a speed.
    [16]
    16. A method for measuring a pressure with a device (1), which has a pipe (2) with a first opening (3) and a first pressure measuring device (4), in particular a device (1) according to one of claims 1 to 12, characterized in that a pressure acting on the first opening (3) is measured indirectly with the first pressure measuring device (4) via a medium located in the pipe (2), which is conveyed by a conveyor, in particular a pump, through the first opening (3) from the pipe (2 ).
    [17]
    17. Method according to claim 16, characterized in that during a measurement of the pressure the medium is conveyed in particular continuously through the first opening (3), preferably at a speed of less than 50 km / h, with an advantage of 1 m / h to 50 m / h, with advantage 5 m / h to 20 m / h, in particular 10 m / h to 15 m / h.
    [18]
    18. The method according to claim 16 or 17, characterized in that the tube (2) during the measurement is completely filled with the medium, on which on the one hand on the first opening (3) acting pressure and on the other hand acts a pressure applied by the conveyor.
    [19]
    19. The method according to any one of claims 16 to 18, characterized in that the medium is a liquid, in particular an antifreeze liquid (24).
    [20]
    20. A method for measuring a velocity, wherein a dynamic pressure and static pressure are measured, characterized in that the dynamic pressure in a method according to one of claims 16 to 19 is measured.
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    同族专利:
    公开号 | 公开日
    WO2016000008A1|2016-01-07|
    AT516021B1|2016-02-15|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20140020479A1|2011-03-31|2014-01-23|Thales|Device for maintaining and analyzing an aerodynamic probe|
    WO2013028220A1|2011-08-19|2013-02-28|Aerovironment Inc.|Water resisitant aircraft pitot device|
    DE102012209352A1|2012-06-04|2013-12-05|Hans-Harald Schack|Device e.g. pitot tube for measuring back pressure in flowing gaseous and/or liquid media, has pipe that is connected to pressure measuring device, and cleaning device which is provided for cleaning lumen of pipe|DE102016119359A1|2016-10-11|2018-04-12|Deutsches Zentrum für Luft- und Raumfahrt e.V.|Dynamic pressure probe for a sensor device and missile with a sensor device|US3349615A|1964-10-30|1967-10-31|Charles W Finkl|Marine speed indicators|
    US3546939A|1968-02-15|1970-12-15|Howard H Hilderbrand|Fluid flow indicator|
    GB0420913D0|2004-09-21|2004-10-20|Talbot John S|Pressure testing apparatus|
    法律状态:
    2019-11-15| MA04| Withdrawal (renunciation)|Effective date: 20190410 |
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50469/2014A|AT516021B1|2014-07-04|2014-07-04|Apparatus and method for measuring a pressure|ATA50469/2014A| AT516021B1|2014-07-04|2014-07-04|Apparatus and method for measuring a pressure|
    PCT/AT2015/050159| WO2016000008A1|2014-07-04|2015-06-24|Device and method for measuring a pressure|
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