Method for adjusting a piezoelectric torque sensor

Abstract

The invention relates to a method for adjusting a piezoelectric torque sensor of a measuring device for determining a torque exerted on a test object as a result of a force flow, the measuring device preferably being part of a test stand, wherein the measuring device has a piezoelectric torque sensor and a second torque sensor based on another measuring principle, which is designed to detect a static torque continuously, wherein the measuring device is set up such that both torque sensors measure the torque in the force flow, wherein a nominal measuring signal of the piezoelectric torque sensor is ascertained on the basis of a torque measurement by the second torque sensor, and wherein a detected measuring signal of the piezoelectric torque sensor is adjusted and outputted on the basis of the ascertained nominal measuring signal.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for adjusting a piezoelectric torque sensor of a measuring device, preferably a test bench, for determining a torque applied at a test object, wherein the measuring device has a piezoelectric torque sensor. BACKGROUND

[0002] In the development and adjustment of engines, in particular combustion engines or electric machines, it is important to know the torque at the engine shaft as precisely as possible, in particular in test bench operation.

[0003] From the prior art it is known to use measuring systems with strain gauges or also with piezoelectric sensors for this purpose.

[0004] Strain gauges and similar measuring elements are generally used to measure static forces. Measuring systems with measuring elements of this type generally have a too long reaction time to measure dynamic force profiles due to their construction.

[0005] Piezoelectric torque sensors have piezoelectric elements which generate a voltage on the basis of the piezoelectric effect when a force acts on them.

[0006] The principle is based on the fact that a voltage occurs at a piezoelectric element when it is deformed elastically. Due to the deformation of the piezoelectric element, a small dipole is formed within the elementary cell of the piezoelectric element. The sum of the associated electric fields in all elementary cells of the piezoelectric element, on deformation or force, leads to a macroscopically measurable voltage. Normally, the charge transfer is measured by means of a charge voltage converter, also called charge amplifier.

[0007] The measuring principle of piezoelectric measuring elements or piezoelectric elements can measure forces which occur for a short time or at certain frequencies well. But the measuring elements of piezoelectric elements are less suitable for measuring forces over a longer period of time, for example steady forces, since the measuring signal is subject to a time drift. Piezoelectric elements are therefore suitable for measuring dynamic tensile, compressive and shear forces. They have a wide dynamic range, are rigid and can also measure high dynamic forces with high resolution at the same time. Piezoelectric sensors have a very high natural frequency due to their construction and therefore hardly influence the system to be measured.

[0008] It is known from the document WO 2019 / 144172 A1 for a force and / or torque measuring device for determining a torque at a torque transmission shaft, which is formed by a bearing device, in particular a machine bearing, of the output shaft and / or input shaft of the torque transmission shaft, wherein the measuring device has at least two, preferably three or four piezoelectric elements and a fixing device, wherein the fixing device carries the piezoelectric elements and is constructed in such a way that the force, in particular the shear force, between the bearing device and a support device for supporting the bearing device can be measured by means of the piezoelectric elements. SUMMARY

[0009] It is therefore the task of the present invention to expand the measurement spectrum of a measuring device for measuring a torque with a piezoelectric torque sensor. The task of the present invention is in particular to provide a method for adjusting a piezoelectric torque sensor of a measuring device for low-frequency ranges of torque vibrations and a test bench with which such an adjustment can be carried out.

[0010] The task is solved by the teaching of the independent claims. Advantageous design proposals are claimed in the dependent claims.

[0011] A first aspect of the present invention relates to a method for adjusting a piezoelectric torque sensor of a measuring device for determining a torque, which is preferably part of a test bench, the torque being exerted at a test object due to a force flow, wherein the measuring device has a piezoelectric torque sensor and a second torque sensor based on another measuring principle, which is designed to continuously detect a static torque, wherein the measuring device is set up in such a way that both torque sensors measure the torque in the force flow, wherein a nominal measurement signal of the piezoelectric torque sensor is ascertained based on the torque measurement by the second torque sensor, and wherein a detected measurement signal of the piezoelectric torque sensor is adjusted and output based on the ascertained nominal measurement signal.

[0012] A second aspect of the present invention relates to a test bench for a machine, preferably an electric machine, for measuring a dynamic torque, wherein the test bench has a piezoelectric torque sensor and a second torque sensor based on another measuring principle, which is designed to continuously detect a static component of the torque, wherein both torque sensors are set up and arranged at the test bench in order to measure the torque in the force flow on the test bench.

[0013] A third aspect of the present invention relates to a measuring device for a machine, preferably an electric machine, for measuring a dynamic torque, wherein the measuring device has a piezoelectric torque sensor and a second torque sensor based on another measuring principle, which is designed to continuously detect a static component of the torque, wherein both torque sensors are set up and arranged for measuring the torque in a unique force flow.

[0014] The measuring device and / or the test bench is preferably intended for testing the test object at a rotational speed of more than about 10 000 U / min, preferably more than about 35 000 U / min and most preferably more than about 100 000 U / min.

[0015] The measuring spectrum is preferably, according to the application, the frequency range in which a reasonable measurement can be performed with the measuring device.

[0016] The test object is preferably, according to the application, a machine to be checked or an overall system consisting of a machine to be checked and a shaft and / or a shafting. The individual elements of the test object are preferably connected to one another in a torsionally rigid manner.

[0017] The adjustment is preferably, according to the application, a setting or correction of the measured values displayed by the measuring device to a deviation from the reference values of the reference device forming the rated values which is as small as possible. The measuring device is usually adjusted when the measuring deviation between the display values of the measuring device and the display values of the reference device is so high during calibration that it is not permitted. When adjusting according to the application, the drift of the signal of the piezoelectric torque sensor is corrected, in particular by means of the signal of the sensor provided for continuously detecting the static torque. Further deviations, for example caused by other effects in a frequency range which differs from the frequency range observed during adjustment, are preferably not detected by the adjustment according to the application.

[0018] The force flow is, according to the application, the course of the force and / or torque in the system of the machine from the point of action, in particular from the introduction point, to one or more points at which the force and / or torque is recorded by means of a reaction force and / or a reaction torque. The force flow consists of the force, in particular the transverse force relative to the direction of rotation of the shaft, and in particular the torque around the axis of rotation.

[0019] The power flow is, according to the application, the course of the power in the system of the machine from the introduction point to one or more points at which the power is reduced.

[0020] The quasi-stationary frequency range preferably has, according to the application, a vibration frequency at which the measurement can be performed by both torque sensors in a balanced state of the torque sensor, respectively. In this balanced state, there is in particular no significant measurement difference at the respective measurement point caused by the vibrations at the test bench, and the response time of the second torque sensor is less with respect to the speed of change of the torque. In this state, in contrast to the measurement at higher frequencies, a drift of the measurement of the piezoelectric torque sensor also occurs.

[0021] The device according to the application can be constructed in hardware and / or software technology and has, inter alia, a preferably digital processing unit, in particular a microprocessor unit (CPU), and / or one or more programs or program modules, preferably in data connection or signal connection with a memory system or a bus system. The CPU can be constructed to process instructions as a program stored in the memory system, to detect input signals of the data bus and / or to emit output signals to the data bus. The memory system can have one or more, in particular different, storage media, in particular different memories, in particular optical, magnetic, solid and / or other non-volatile media. The program can be so obtained that it embodies or implements the method described herein and the CPU implements the steps of this method.

[0022] The measuring flange according to the application is preferably a torque sensor which has two flanges between which the applied torque can be measured.

[0023] The application is based on the recognition that, when there is sufficient spacing from possible natural or resonant modes of the test rig, the piezoelectric torque sensor can be adjusted by means of a second torque sensor which is arranged in the same force flow as the piezoelectric torque sensor.

[0024] The reference signal is measured here by means of the second torque sensor in the force flow in which the piezoelectric torque sensor also measures the torque. The nominal measurement signal of the piezoelectric torque sensor is calculated on the basis of this reference signal. The measurement signal of the piezoelectric torque sensor can be adjusted by means of this nominal measurement signal. This measurement signal, which is corrected by means of the adjustment, can then be output to the user or via a data interface for further data processing.

[0025] The dynamic component of the torque can be measured with high accuracy by means of the piezoelectric torque sensor. Conversely, in the low-frequency component of the torque, the greater signal drift of the piezoelectric element begins to play a role, so that the piezoelectric torque sensor can only detect this component incorrectly. Conversely, the second torque sensor measures the static component of the torque at low frequencies, but cannot map the high-frequency signal components. Low-frequency operating conditions are given, inter alia, when the test object has a vibration frequency of less than 10 Hz. Test rigs usually have a natural vibration in the range from 50 Hz to 80 Hz. The adjustment should therefore be carried out when the vibration frequency is no greater than 10 Hz, so that the influence of the natural vibration can be ruled out.

[0026] This adjustment or readjustment can be carried out periodically or continuously for the piezoelectric torque sensor by means of the measuring device according to the application, so that the torque can also be measured accurately at frequencies of less than 1 Hz. Steady-state forces or torques can therefore also be measured by means of the application.

[0027] Therefore, the measurement spectrum of piezoelectric torque sensors can be extended to the low-frequency vibration range, especially up to the static range, through this invention.

[0028] In an advantageous design of the method, the rated measurement signal of the piezoelectric torque sensor is also determined based on the shaft rotational speed measurement. Because the shaft rotational speed is taken into account, different moments of inertia in different parts of the transmission system or the test object can be considered during adjustment.

[0029] In another advantageous design of the method, the rated measurement signal of the piezoelectric torque sensor is obtained using the following equation:

[0030]

[0031] in,

[0032] M Piezo_cal It is the rated measurement signal.

[0033] M W The torque is measured by means of the second torque sensor at a shaft or shaft system that is torsionally connected to the test object or is a component of the test object.

[0034] J W It is the moment of inertia of the shaft or shaft system that is torsionally connected to the test object (5) or is a component of the test object (5).

[0035] J UUT It is the moment of inertia of the test object.

[0036] It is the time derivative of the measured rotational speed of the shaft (10a, 10b, 10c) or shaft system that is torsionally connected to or is a component of the test object, and

[0037] M R This is especially the frictional torque caused by bearings and / or transmission mechanisms.

[0038] The present invention has recognized that, by means of this relatively simple equation, which in particular forms the basis of the model, a reliable value of the rated measurement signal of the piezoelectric torque sensor can be obtained, which has a great degree of consistency with the actual value of the torque at the measurement site.

[0039] In another advantageous design of the method, a model of the controlled system, namely the measurement signal-rated measurement signal, is generated based on the detected measurement signal and the rated measurement signal calculated at the same time point. The detected measurement signal is then adjusted using the model after its generation. Generating the model allows for speed-related adjustments without further measurement.

[0040] In another advantageous design of the method, the model is based on a transfer function, the parameters of which are determined by test bench experiments at the test object in such a manner that a measurement signal detected by means of a piezoelectric torque sensor is compared with a rated measurement signal determined based on torque measurement using a second torque sensor. This allows for simple adjustments.

[0041] In another advantageous design of the method, a piezoelectric torque sensor measures the reaction torque at at least one support point of the test object to determine the corresponding applied torque. In an advantageous design of the test bench, the piezoelectric torque sensor is constructed and arranged in such a manner that the force flow between the test object and the support device used to support it can be measured. The reaction torque, by virtue of which the test object is supported, is also ultimately determined here. By averaging the torque at the test object based on the reaction torque, it is unnecessary to measure at rotating components of the test object to determine the torque. This prevents altering the moment of inertia of the measuring device or introducing elasticity into the measuring device through measuring devices at rotating components, such as measuring flanges.

[0042] The advantages and features previously described with reference to the first aspect of the invention are applicable accordingly to the second aspect of the invention, and vice versa.

[0043] In an advantageous design, the test bench has a load-bearing device, particularly a force gauge or braking system, to apply a load to the test object. Dynamic measurements can be performed at the test bench using the force gauge.

[0044] In another advantageous design, the test bench has a transmission mechanism, particularly an acceleration transmission mechanism, arranged in the force flow between the load device and the test object, wherein a piezoelectric torque sensor is arranged to detect torque on the side of the test object that is positioned relative to the force flow of the transmission mechanism, and a second torque sensor is arranged to detect torque on the side of the load device that is positioned relative to the force flow of the transmission mechanism.

[0045] This invention is particularly advantageous in a test bench apparatus with a transmission mechanism, because a piezoelectric torque sensor is preferably arranged on the side of the force flow that rotates at a high speed. Here, the high-frequency vibrations generated by the transmission mechanism can be determined by means of the piezoelectric torque sensor. Conversely, other types of second torque sensors, particularly those based on strain gauge devices, measure the torque on the side of the transmission mechanism that rotates at a lower speed. This allows measurements to be performed at low torque vibration frequencies, i.e., so-called quasi-steady-state measurements or even steady-state measurements. The force flow is transformed, in particular, from a low-dynamic force flow to a high-dynamic force flow. The low-frequency components of the torque vibration are transformed through this conversion. The arrangement of the second torque sensor on the side of the transmission mechanism that rotates at a higher speed is particularly disadvantageous, because it is impossible to determine torques with high vibration frequencies by means of a second torque sensor that is not based on a piezoelectric measurement principle. However, the equations shown above are also particularly applicable to the relationship between the torque measured by the second torque sensor and the rated measurement signal of the piezoelectric torque sensor.

[0046] In another advantageous design of the method, the shaft system has a transmission mechanism, wherein a second torque sensor is arranged in the section of the transmission mechanism that rotates at a lower speed, and a piezoelectric torque sensor is arranged in the section of the transmission mechanism that rotates at a higher speed. This design is particularly advantageous because the torque vibrations occurring at extremely high frequencies in the higher-speed sections of the shaft system can be well determined by the piezoelectric torque sensor.

[0047] In another advantageous design, the test bench has a rotational speed sensor, which is set and arranged to measure the rotational speed of the object being tested.

[0048] In another advantageous design of the test bench, the transmission mechanism forms a shaft system with at least one shaft, and the speed sensor is arranged in such a way that the speed is detected on the side of the shaft system with respect to the transmission mechanism where the load device is arranged.

[0049] In another advantageous design of the test bench, the measurement principle of the second torque sensor is based on a strain gauge, and the second torque sensor is preferably a measuring flange. Strain gauge-based torque sensors are particularly well-suited for measuring torque or force based on torque in steady-state and quasi-steady-state conditions or at low frequencies.

[0050] In another advantageous design, the test object and load device, if present, support the transmission mechanism on the same base.

[0051] In another advantageous design, the test bench has an adjustment device for continuously adjusting the piezoelectric torque sensor, wherein the torque detected by the piezoelectric torque sensor is adjusted by the adjustment device using a model. Attached Figure Description

[0052] Further features and advantages will become apparent from the following description of the embodiments with reference to the accompanying drawings. In the drawings:

[0053] Figure 1 An embodiment of a test bench with a piezoelectric torque sensor and a second torque sensor is shown at least partially schematically;

[0054] Figure 2 A block diagram, at least partially schematic, illustrates a method for adjusting the torque of a piezoelectric element; and

[0055] Figure 3 An embodiment of a controlled system for adjusting the measurement signal of a piezoelectric torque sensor is shown at least partially schematically. Detailed Implementation

[0056] Figure 1 An embodiment of the test bench 1 for testing the machine is shown.

[0057] The invention will now be explained using a test bench 1 for testing motor 5. However, it will be apparent to those skilled in the art that the illustrated embodiments can also be used for other types of machines, particularly electromechanical energy converters or chemical-mechanical energy converters.

[0058] The test bench 1 preferably has a force gauge 7, which can provide a load and apply a load, especially a driving torque or braking torque, to the motor to be tested.

[0059] The test bench 1 shown is preferably used to test this type of motor, which operates for more than 10,000 minutes during normal operation. -1 Preferably greater than 35000 min -1 And the most preferred value is greater than 100,000 min -1 The test bench operates at a higher speed. This is, for example, the electrical drive of a compressor, such as a turbocharger, or the electrical drive motor used in electric vehicles. This high speed cannot be provided by or recorded by the force gauge 7. Therefore, the test bench 1 preferably has a transmission mechanism 8, in particular a so-called acceleration transmission mechanism, which converts the speed at the shaft sections 10b, 10c that torsionally connect the force gauge 7 to the acceleration transmission mechanism 8 into a higher speed. This converted higher speed is transmitted to the motor 5 to be tested through the shaft section 10a that torsionally connects the acceleration transmission mechanism 8 to the motor 5 to be tested. In turn, the speed provided by the motor 5 to be tested is converted by the acceleration transmission mechanism 8 into the speed and torque range within which the force gauge can operate.

[0060] The transmission mechanism 8 and different shafts or shaft sections 10a, 10b, 10c together form a shaft system. The test object is formed solely by the motor 5, or by the motor 5 and at least partially by the shaft system, depending on which components should be tested.

[0061] As in Figure 1 As shown, the force gauge 7, the acceleration transmission mechanism 8, and the motor 5 to be tested are supported on the same base 11. The motor 5 to be tested is supported relative to the base 11 by a support device 6. The support device 6 provides a reaction force to the motor 5 to be tested, thereby supporting the force and power flow between the motor 5 to be tested and the force gauge 7.

[0062] The support device 6 is preferably as follows: Figure 1 As shown, it is constructed in such a way that the motor 5 to be tested can be supported on the side of the shaft on which the motor 5 is arranged, or on the side of the shaft end 10a that can be connected to the motor shaft, particularly the end side. This arrangement provides the advantage that, as... Figure 1 As shown, the torque sensor 3 can be arranged between the support device 6 and the motor 5 to be tested such that most of the torque acting on the motor 5 to be tested is applied to the piezoelectric torque sensor 3. In particular, this arrangement can minimize or even eliminate force diversion that does not pass through the piezoelectric torque sensor 3. For this method of supporting the motor 5 to be tested via the piezoelectric torque sensor 3 and the support device 6, both the piezoelectric torque sensor 3 and the support device 6 preferably have a shaft for the motor 5 to be tested or a through hole for the shaft or shaft section 10a. This through hole is preferably constructed as a bore.

[0063] However, the motor 5 to be tested can also be supported in other ways, such as on the side facing the base 11, or on the side facing away from the base, in a suspended manner, or on other sides of the motor 5 to be tested. Regarding Figure 1 The details of the support for the motor 5 to be tested, other feasible options for the support, and the details of determining the reaction force by means of the piezoelectric torque sensor 3 can be derived from the reference WO 2019 / 144172 A1 at the beginning of this article.

[0064] The test bench 1 is divided into two sides, I and II, by the acceleration transmission mechanism 8. On the first side I, where the motor 5 to be tested is arranged, the shaft system rotates at a higher speed, wherein a lower torque is applied to the shaft system. This section of the shaft system is therefore also referred to in this specification as the first section I of the shaft system.

[0065] On the side referred to as the second side II at the other output end of the acceleration transmission mechanism 8, shaft sections 10b and 10c rotate at lower speeds and with higher applied torque. The transmission ratio of the acceleration transmission mechanism 8 is typically about 3:1 to 10:1. This section of the shaft system is therefore also referred to in this specification as the first section II of the shaft system.

[0066] The preferred shaft system or transmission system comprises an electric motor 5, shaft sections 10a, 10b, 10c, an acceleration transmission mechanism 8, and a force gauge 7, relating to a system capable of vibration. The resonant or intrinsic mode of the vibration depends on the design of the test bench 1 and the electric motor 5 to be tested, and is typically greater than 50 Hz.

[0067] To determine the torque acting on the motor 5 to be tested due to the force flow from or to the force gauge 7, the test bench 1 has a piezoelectric torque sensor 3. This torque sensor 3 preferably does not directly determine the torque applied to the motor 5 to be tested through shaft section 10a, but rather indirectly determines the reaction torque by which the motor 5 to be tested is supported at the support device 6. Furthermore, the test bench 1 has a second torque sensor 4, which measures torque not based on the piezoelectric measurement principle, but by means of other measurement principles. Here, a strain gauge, as is commonly known in the prior art, is preferably used. The second torque sensor 4 is preferably configured as a measuring flange that measures the torque between the two shaft sections 10b and 10c.

[0068] Two torque sensors in Figure 1 The arrangement shown is particularly advantageous for adjusting the piezoelectric torque sensor 3, because smaller vibrations typically occur in the second section II of the shaft system, which rotates at a lower speed, and measurements are accurate using the second torque sensor 4 employing a strain gauge. Strain gauge-based sensors are, of course, only suitable for dynamic measurements in limited ways.

[0069] Conversely, the piezoelectric torque sensor 3 is arranged in the first section I of the shaft system, directly at the motor 5 to be tested, where the applied torque should also be determined. By directly placing the piezoelectric torque sensor at the test object, high accuracy in measuring the applied torque can be achieved.

[0070] To determine the rotational speed of the shaft system, particularly in the second section II of the shaft system, a speed sensor 9 capable of determining the rotational speed is arranged. Figure 1 In this system, the speed sensor 9 determines the speed of the shaft of the force gauge 7, and therefore the speed of shaft sections 10b and 10c. Thus, the speed in the first section I of the shaft system can also be deduced by the selected transmission ratio of the acceleration transmission mechanism 8.

[0071] Based on the torque M measured by the second torque sensor 4 W and the rotational speed ω measured by the rotational speed sensor 9 W Considering, in particular, the frictional torque M caused by the bearings and / or the acceleration transmission mechanism 8, R The moment of inertia J of the shaft system W and the moment of inertia J of the motor 5 to be tested UUT Under these circumstances, determine the rated measurement signal M. Piezo_cal This will be explained in more detail below with reference to a method 100 for adjusting a piezoelectric torque sensor according to the invention.

[0072] Simultaneously, the actual measurement signal M of the torque applied to the piezoelectric torque sensor 3 can be measured using the piezoelectric torque sensor 3. Piezo .

[0073] To calibrate the actual measurement signal of the piezoelectric torque sensor 3, the test bench 1 preferably also includes adjustment devices 12. These adjustment devices are preferably part of the data processing unit of the test bench 1, but can also be part of an external data processing unit. This is done during the calibration of the actual torque signal M. Piezo The piezoelectric torque sensor 3 can then be adjusted using the adjusting device 12. Preferably, a model stored in the adjusting device 12 is used for calibration or adjustment. This model is further explained in more detail below with reference to the method 100.

[0074] Figure 2 A block diagram illustrating an embodiment of a method 100 for adjusting a piezoelectric torque sensor of measuring device 2 is shown. This measuring device 2 is preferably the one previously referenced. Figure 1 Part of the test bench 1 described.

[0075] The piezoelectric torque sensor 3 is adjusted during continuous operation of the test bench. To do this, torque is applied to the force gauge 7 via the shaft system using the motor 5 to be tested, or vice versa, torque is applied from the force gauge 7 to the motor 5 to be tested.

[0076] During adjustment, test bench 1 is preferably operated at a lower rotational speed of the shaft system, wherein the rotational speed is preferably less than 50 min in the second section II of the shaft system. -1 Within this range of rotational speeds, depending on the construction of the test bench 1 and the test object, a small vibration frequency of less than about 10 Hz, preferably less than about 5 Hz, and even more preferably less than about 1 Hz, is expected for the torque.

[0077] This frequency range of vibration is chosen in such a way that there is a gap between the resonant frequency or eigenmode of the total system consisting of test bench 1 and the test object. The resonant frequency or eigenmode is typically about 50 Hz.

[0078] These frequency ranges suitable for adjustment of the vibration frequency are further preferably isolated by means of frequency filters, especially by means of Fourier analysis. The rotational speed during test bench operation is not important for adjustment in this case.

[0079] During operation, the piezoelectric torque sensor 3 measures the torque applied to the motor 5 under test, 101a. (As already referenced...) Figure 1 As explained, the piezoelectric torque sensor 3 preferably detects the reaction force used to support the motor 5 under test at the support device 6. The second torque sensor 4 detects the torque of 101b in the shaft system and is therefore located at a greater distance from the motor 5 under test. Figure 1 In the test bench 1 or test object with transmission mechanism 8 shown, the second torque sensor 4 is preferably arranged in the area of ​​the shaft system with a relatively low rotational speed.

[0080] Based on torque measurement M via the second torque sensor 4 W and the rotational speed ω measured by the rotational speed sensor 9 W Calculate the rated measurement signal M of 102 Piezo_cal The rated measurement signal is preferably derived based on the following equation:

[0081]

[0082] However, in principle, the friction torque M can also be considered when necessary. R In almost all cases, the torque M measured by the second torque sensor 3 will be used. W Used to determine the rated measurement signal M Piezo_cal .

[0083] Based on the derived rated measurement signal M Piezo_cal The measurement signal M detected by correction 103 Piezo A further preferred approach is to output 104 corrected measurement signals.

[0084] The measurement signal M detected by the piezoelectric torque sensor 3 Piezo The correction is preferably performed using the measurement signal / rated measurement signal obtained by the controlled system.

[0085] Examples of such controlled systems are in Figure 3 As shown in the image.

[0086] The measurement signal M is preferably corrected in the following manner. Piezo That is, to compare this measurement signal with the rated measurement signal M. Piezo_cal In comparison, the correction value obtained in this way, preferably at a lower frequency of torque vibration, is applicable to the entire measurement range, and in particular to higher frequencies of torque vibration.

[0087] Furthermore, in a preferred embodiment, a model is generated by which the rated measurement signal M can be determined based on the vibration frequency of the torque and the measurement of the second torque sensor 4. Piezo_cal .

[0088] exist Figure 3 The controlled system shown is essentially mapped to the method described above for calculating the rated measurement signal M. Piezo_cal The equation.

[0089] The rotational speed ω of the shaft W The time-derived value is multiplied by the sum of the moment of inertia of the shaft system and the motor 5 to be tested. The torque M is measured using the second torque sensor 4. W Subtract the frictional torque M, which is a function of rotational speed n and transmission ratio T. R The product of this and the previously calculated signal is then passed through a low-pass filter LP to derive the nominal measurement signal M. Piezo_cal The rated measurement signal M Piezo_cal The measurement signal M, which was corrected based on the old adjustment, Piezo Subtracting this, the measured signal also passes through a low-pass filter LP. The low-pass filter LP shown here preferably has the same characteristics, particularly the same dynamics, limiting frequency, order, and type. By setting a low-pass filter, the vibration frequency of the measured signal suitable for adjusting a piezoelectric torque sensor can be isolated.

[0090] The difference is fed to the integrator at a rate of 1 / s. If the calculated acceleration of the shaft rotation is less than the limit, the previous adjustment is replaced by the new value S in integrator 1 and used to correct the measurement signal M measured by the piezoelectric torque sensor 3. Piezo .

[0091] By taking into account the limit of rotational acceleration, it is ensured that the adjustment is not changed only at a certain vibration frequency.

[0092] The embodiments described above are merely examples and should not be construed as limiting the scope of protection, application, or structure in any way. Rather, those skilled in the art have been given instructions to implement at least one embodiment through the foregoing description, wherein various changes in the function and arrangement of the described components can be made without departing from the scope of protection derived from the claims and such equivalent combinations of features. In particular, the various embodiments can be combined with each other.

[0093] List of reference numerals

[0094] 1. Test bench

[0095] 2. Measuring device

[0096] 3. Piezoelectric torque sensor

[0097] 4. Second torque sensor

[0098] 5 motors

[0099] 6. Support device

[0100] 7. Force gauge

[0101] 8. Transmission Mechanism

[0102] 9. Speed ​​sensor

[0103] 10a, 10b, 10c axes

[0104] 11. Base

[0105] 12 Adjusting the device

Claims

1. A method (100) for adjusting a piezoelectric torque sensor (3) of a measuring device (2) for determining the torque applied to a test object (5) due to a force flow, wherein, The measuring device (2) has a piezoelectric torque sensor (3) and a second torque sensor (4) based on other measurement principles. The second torque sensor is designed to continuously detect static torque. The measuring device (2) is configured such that the two torque sensors measure (101a, 101b) the torque in the force flow. The rated measurement signal of the piezoelectric torque sensor (3) is derived (102) based on the torque measurement by the second torque sensor (4). The measured signal detected by the piezoelectric torque sensor is adjusted (103) and output (104) based on the derived rated measurement signal.

2. The method (100) according to claim 1, wherein, Within the quasi-steady-state frequency range of the torque vibration frequency at the measuring device, i.e., within the frequency range below 50 Hz, the rated measurement signal of the piezoelectric torque sensor (3) is determined.

3. The method (100) according to claim 1 or 2, wherein, The rated measurement signal of the piezoelectric torque sensor (3) is determined within the frequency range of the torque vibration frequency where no inherent vibration mode or resonant mode appears in the measurement environment, i.e., at the torque vibration frequency of less than 20 Hz.

4. The method (100) according to claim 2, wherein, Adjustments are made during continuous operation of the test object (5), wherein torque within the desired frequency range is isolated by means of a frequency filter.

5. The method (100) according to claim 1 or 2, wherein, The rated measurement signal of the piezoelectric torque sensor (3) is also determined based on the rotational speed measurement of the test object.

6. The method (100) according to claim 1 or 2, wherein, The rated measurement signal of the piezoelectric torque sensor (3) is obtained using the following equation: in, M Piezo_cal It is the rated measurement signal. M W The torque is measured by means of the second torque sensor (4) at a shaft (10a, 10b, 10c) or shaft system that is torsionally connected to or is a component of the test object (5). J W It is the moment of inertia of the shaft (10a, 10b, 10c) or shaft system that is torsionally connected to or is a component of the test object (5). J UUT It is the moment of inertia of the test object (5). It is the time derivative of the measured rotational speed of the shaft (10a, 10b, 10c) or shaft system that is torsionally connected to or is a component of the test object (5). M R The frictional torque is caused by the bearing and / or transmission mechanism (8).

7. The method (100) according to claim 6, wherein, The shaft system has a transmission mechanism (8), wherein the second torque sensor (4) is arranged with respect to the transmission mechanism (8) in a shaft section that rotates at a lower speed and the piezoelectric torque sensor (3) is arranged with respect to the transmission mechanism (8) in a shaft section that rotates at a higher speed.

8. The method (100) according to claim 1 or 2, wherein, The piezoelectric torque sensor (3) measures the reaction torque at at least one support portion of the test object (5) in order to determine the torque applied to the test object (5).

9. The method (100) according to claim 1, wherein, Within the quasi-steady-state frequency range of the torque vibration frequency at the measuring device, i.e., within the frequency range between 5Hz and 50Hz, the rated measurement signal of the piezoelectric torque sensor (3) is determined.

10. The method (100) according to claim 1 or 2, wherein, The rated measurement signal of the piezoelectric torque sensor (3) is determined within the frequency range of the torque vibration frequency that does not exhibit an inherent vibration mode or resonant mode on the test bench (1), i.e., at the torque vibration frequency of less than 10 Hz.

11. The method (100) according to claim 2, wherein, Adjustments are made during continuous operation of the test object (5), wherein torque within the desired frequency range is isolated by means of Fourier analysis.

12. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method (100) according to any one of claims 1 to 11.

13. A computer-readable medium having a computer program stored thereon according to claim 12.

14. A test bench (1) for measuring dynamic torque of a machine, configured to perform the method according to any one of claims 1 to 11, wherein, The test bench (1) has a piezoelectric torque sensor (3), an adjustment device (12) and a second torque sensor (4) based on other measurement principles. The second torque sensor is designed to continuously detect the static component of the torque. The adjustment device (12) is configured to adjust the piezoelectric torque sensor (3). The two torque sensors (3, 4) are arranged and positioned on the test bench (1) in such a way that the torque in the force flow can be measured on the test bench (1).

15. The test bench (1) according to claim 14, wherein, The piezoelectric torque sensor (3) is constructed and arranged such that it can measure the force in the force flow between the test object (5) and the support device (6) for supporting the test object (5).

16. The test bench (1) according to claim 14 or 15, with a load device (7) for applying load to the test object (5).

17. The test bench (1) according to claim 16, having a transmission mechanism (8) arranged in the force flow between the load device (7) and the test object (5), wherein, The piezoelectric torque sensor (3) is arranged to detect the torque on the side I of the test object (5) on which the force flow with respect to the transmission mechanism (8) is arranged, and the second torque sensor (4) is arranged to detect the torque on the side II of the load device (7) on which the force flow with respect to the transmission mechanism (8) is arranged.

18. The test bench (1) according to claim 14 or 15, wherein, The measurement principle of the second torque sensor (4) is based on a strain gauge and the second torque sensor (4) is a measuring flange.

19. The test bench (1) according to claim 14, wherein, The machine in question is an electric motor.

20. The test bench (1) according to claim 16, wherein, The load device (7) is a force gauge or a brake.

21. The test bench (1) according to claim 17, wherein the transmission mechanism (8) is an acceleration transmission mechanism.

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