DE102012022982A1 - Torque measuring device and method for measuring a torque - Google Patents

Abstract

The invention relates to a torque measuring device, comprising a stator, a rotor, a torque measuring transducer provided on the rotor, a signal generating device for generating a switching signal from the torque measuring signal, at least one provided on the stator primary coil which can be powered by a supply voltage source with alternating current at least one secondary coil provided to the rotor for energizing the torque transducer and the signal generator, the secondary coil voltage being induced by the primary coil energized by the supply voltage source in the secondary coil, at least one modulation device provided on the rotor for modulating the coil current in the secondary coil at least one evaluation device provided on the stator and configured to detect the coil current modulation induced by modulating the coil current of the secondary coil in the primary coil. The invention also relates to a method for measuring a torque.

Description

The invention relates to a torque measuring device and a method for measuring a torque.

A stator and a rotor having torque measuring devices are known. The rotor is rotatably mounted on the torque transmitting device for measuring the respective torque, wherein the torque applied to the rotor is measured by means of a torque sensor provided on the rotor. The measured torque measurement signal is usually converted into a frequency or digital signal and then transferred without contact to a provided on the stator signal-receiving device, which is at least partially disposed around the rotor.

The non-contact transmission takes place for example in one of the WO 2009/062481 A1 known solution by driving a light-emitting diode provided on the rotor by a signal frequency-modulated by means of the measuring signal and receiving the frequency-modulated light signal provided by the control by means of a signal receiving device in the form of a photocell provided on the rotor. At the time of the DE 10 2004 015 771 B4 known solution is the non-contact transmission of the frequency-modulated signal to the stator inductively or by inductive coupling. All known solutions have in common that for the production of complex components provided or specially manufactured, accompanied by a high production cost and high production costs.

The invention is therefore based on the object to provide a torque measuring device, which is much cheaper to produce compared to the known solutions, and to provide a method for measuring a torque, which is feasible compared to the known solutions with significantly lower cost.

This object is achieved with a torque measuring device with the features of claim 1 and with a method for measuring a torque with the features of claim 9.

The torque measuring device according to the invention has a torque measuring transducer provided on the rotor for measuring a torque acting on the rotor and for outputting a torque measuring signal. Furthermore, the torque measuring device according to the invention comprises a signal generating device for generating a switching signal from the torque measurement signal, at least one provided on the stator primary coil, which is powered by a supply voltage source with alternating current, at least one provided on the rotor secondary coil, which is used to power the torque sensor and the signal generating means is provided by a secondary coil voltage of the secondary coil, wherein the secondary coil voltage is induced by the supplied by the supply voltage source primary coil in the secondary coil, at least one provided on the rotor modulation device for modulating the coil current in the secondary coil, said Modulation device for modulating the coil current in accordance with the switching signal from this can be controlled, and at least one provided on the stator evaluation, which is set by the da s modulating the coil current of the secondary coil in the primary coil induced coil current modulation to detect.

The operation of the device according to the invention is based on the modulating of the coil current in the secondary coil according to the switching signal by means of the modulation device and the detection of the current induced by modulating the coil current of the secondary coil in the primary coil coil current modulation by means of the evaluation. The modulation of the coil current in the secondary coil or the coil current modulation in the primary coil depends on the time characteristic of the torque measurement signal since the switching signal or modulation signal generated by the signal generation input is also dependent on the temporal progression of the signal Torque measuring signal depends. This mode of operation therefore makes it possible to transmit the information contained in the torque measurement signal contactlessly to the stator or the evaluation unit by means of a modulation of the coil current in the secondary coil which can be carried out in a simple and practical manner via the torque acting or transmitted to the rotor. The particularly necessary for the realization of this transmission signal generating device and modulation device, can advantageously in a simple and practical way z. B. are constructed or formed from inexpensive electronic components, along with a significant reduction of the manufacturing cost and manufacturing costs over the known solutions.

The stator is preferably arranged at least in sections or entirely around the rotor.

In a practical embodiment of the invention Torque measuring device, the torque measurement signal is an analog torque measurement signal or the torque transducer is set up to output the measurement result as an analog torque measurement signal. Preferably, in this practical embodiment, the signal generating device is adapted to generate from the analog torque measurement signal dependent on the temporal waveform of the analog torque measurement signal switching signal or modulation signal, wherein the switching signal or modulation signal preferably by the analog torque measurement signal frequency-modulated carrier signal or preferably a pulse width modulated by the analog torque measurement signal carrier signal. Due to the intended frequency modulation or pulse width modulation, distortions due to amplitude changes, which can occur due to environmental influences, can advantageously be avoided during transmission.

In the above practical embodiment, the signal generating means may also comprise a digital-to-analog converter for converting the analog torque measurement signal into a timing signal dependent digital switching signal. Even by digitizing the analog torque measurement signal, it is advantageously possible to avoid distortions due to amplitude changes during transmission, which can occur as a result of environmental influences.

In a preferred embodiment, the modulation device comprises a switching device provided on the rotor for short-circuiting the secondary coil, which can be controlled by the switching signal for temporally successive short-circuiting of the secondary coil, wherein the evaluation device is set up, which by the temporally successive short-circuiting induced in the primary coil Spulenstrom- Capture modulation. The modulation of the coil current of the secondary coil by short-circuiting by means of a switching device provided on the rotor can be realized in a very simple and practical manner by means of one or more electronic components, such as in particular by means of a transistor.

For measuring or detecting the torque transmitted by a shaft, the rotor may preferably be designed in the form of a flange which can be fastened rotationally fixed on a shaft.

Due to the above-described simple and inexpensive construction of the torque measuring device according to the invention, this is particularly suitable for torque measurement or torque detection of rotatable parts of devices that are used in everyday life - ie in particular for such devices that are produced in a large variety and in which a cost-optimized production is in the foreground. The torque measuring device according to the invention may be particularly preferably provided for torque measurement or torque detection on a pedal of a bicycle or for torque measurement or torque detection in the region of the pedals of a bicycle.

The method according to the invention for measuring a torque comprises the following steps: (A) measuring a torque acting on a rotor, (B) generating a switching signal dependent on the time course or the time profile of the measured torque, (C) modulating a coil current in a secondary coil according to the switching signal, and (D) detecting the coil current modulation induced by modulating the coil current of the secondary coil in a primary coil.

By naming the steps with the letters A to D, no exclusive binding to a chronological order is pursued. The letters serve only for naming or marking the steps. In particular, the method according to the invention can be carried out in such a way that steps A to D are carried out at the same time or substantially simultaneously.

The inventive method can be carried out in particular using the torque measuring device according to the invention. As can be seen from the above for the torque measuring device according to the invention, the method according to the invention can be carried out in comparison to the known solutions with significantly lower cost usage. In particular, step C of the method according to the invention can be realized in a very simple and practical manner by means of a modulation device provided on the rotor.

In a practical embodiment of the method according to the invention, a signal is generated from the coil current modulation detected in step D, from which the time profile of the measured torque can be provided by multiplication by a constant factor. Since the coil current modulation in the primary coil-as a result of the dependence of the switching signal on the time profile of the measured torque or the time waveform of the measured torque-depends on the time profile of the measured torque, advantageously a signal can be generated by conversion or signal processing from which the time profile of the measured torque can be provided by multiplication by a constant factor.

It is understood that the features of the solutions presented above or in the claims can be used both individually and jointly, the latter correspondingly causing an accumulation of the advantages of the corresponding features.

Further advantages, objects and characteristics of the present invention will be explained with reference to the following description of appended drawings. In the drawings show:

1 a sectional view of an embodiment of a torque measuring device according to the invention, and

2 a very schematic representation of the embodiment.

This in 1 in a sectional representation of an embodiment of a torque measuring device according to the invention 10 has a stator 12 and a rotor 14 on. To measure the torque transmitted by a shaft is the rotor 14 in the form of a rotatably mounted on or on a shaft flange 14 educated. On the rotor 14 is a torque transducer 16 with strain gages 18 intended. With the strain gauges 18 can be a distortion of the rotor in the form of a flange 14 , which is proportional to the acting or transmitted torque, are detected.

The stationary or immovable stator 12 is in sections around the rotor 14 arranged around. At the stator 12 is a primary coil 20 provided, which is powered by a supply voltage source with alternating current (in 1 not shown). On the rotor 14 is a secondary coil 22 intended. One also on the rotor 14 provided electronics 24 includes, among other things, a signal generator for generating a switching signal from the torque measurement signal of the torque sensor and a modulation device for modulating the coil current in the secondary coil (in 1 not shown in detail), wherein the modulation device for modulating the coil current in accordance with the switching signal from this is controllable.

Based on 2 , which shows a very schematic representation of the embodiment, the structure of the torque measuring device according to the invention will be explained in more detail below.

The on the rotor 14 provided torque transducers 16 for measuring one on the rotor 14 acting torque and to output an analog torque measurement signal has a strain gauge bridge 26 on.

The signal generator 28 for generating a switching signal from the analog torque measurement signal comprises an amplifier 30 and a controller 32 , The controller 32 has a pulse width modulation function and is set up after amplification of the analog torque measurement signal by the amplifier 30 to generate a dependent of the temporal waveform of the analog torque measurement signal switching signal from the amplified torque measurement signal, wherein the switching signal is in the form of a pulse width-modulated by the analog torque measurement signal carrier signal. A typical frequency of this carrier signal is z. At 300 Hz.

Alternatively, the controller 32 also have a frequency modulation function and be set up after the amplification of the analog torque measurement signal by the amplifier 30 to generate from the amplified torque measurement signal a switching signal, which is designed in the form of a frequency-modulated by the analog torque measurement signal carrier signal. Another alternative may provide that the controller 32 a digital-to-analog converter capable of converting through the amplifier 30 amplified analog torque measurement signal is provided in a dependent of the temporal waveform digital switching signal.

The on the stator 12 provided primary coil 20 is from a supply voltage source 34 can be supplied with alternating current, the supply voltage source 34 a controller 36 and a transistor 38 having, which as a switching means 38 for providing the corresponding AC voltage in the desired AC voltage frequency - typically z. B. can be at about 40 kHz - from the controller 36 is controlled.

The on the rotor 14 provided secondary coil 22 is for powering the torque transducer 16 and the signal generator 28 by a secondary coil voltage of the secondary coil 22 provided, wherein the secondary coil voltage from that by the supply voltage source 34 energized primary coil 20 in the secondary coil 22 is induced. For smoothing and rectifying the secondary coil voltage is also an electronic device 40 provided with smoothing function and rectifying function.

The on the rotor 14 provided modulation device 42 for modulating the coil current in the secondary coil 22 is for modulating this coil current in accordance with the switching signal from this controllable. The also from the secondary coil voltage of the secondary coil 22 With Power powered modulation device 42 comprises a switching device in the form of a transistor 44 for short-circuiting the secondary coil 22 , that of the switching signal for temporally successive shorting of the secondary coil 22 is controllable.

The rectifying function of the above electronic device 40 allows in this embodiment, the driving of the transistor 44 for short-circuiting the secondary coil 22 , that this works or works only with rectified current. The electronic device 40 also has capacitors and diodes, not shown, for short circuiting the secondary coil 22 through the transistor 44 in its potentially damaging effect on the controller 32 and the amplifier 30 the signal generator 28 and in its possibly damaging effect on the torque transducer 16 advantageous to weaken.

One on the stator 12 provided evaluation device 46 is set up by modulating the coil current of the secondary coil 22 in the primary coil 20 to detect induced coil current modulation, so by the temporally successive short-circuiting in the primary coil 20 induced coil current modulation. By the short-circuiting in the primary coil 20 To separate induced coil current modulation of higher-frequency components, has the evaluation 46 a low pass (not shown) on.

That in the 1 and 2 illustrated embodiment of the torque measuring device according to the invention 10 Accordingly, it can be used in particular for carrying out an embodiment of a method according to the invention for measuring a torque, which comprises the following steps:

• (A) Measure the on the rotor 14 acting torque,
• (B) generating a dependent of the time course of the measured torque switching signal by the signal generating means 28 .
• (C) modulating a coil current in the secondary coil 22 in accordance with the switching signal by the modulation device 42 , and
• (D) Detecting by modulating the coil current of the secondary coil 22 in the primary coil 20 induced coil current modulation by the evaluation 46 ,

LIST OF REFERENCE NUMBERS

10

Torque measuring device

12

stator

14

rotor

16

Drehmomentmessaufnehmer

18

Strain gauges

20

primary coil

22

secondary coil

24

electronics

26

Strain gauge bridge

28

Signal generator

30

amplifier

32

controller

34

Supply voltage source

36

controller

38

transistor

40

electronic device

42

modulation device

44

transistor

46

evaluation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2009/062481 A1 [0003]
• DE 102004015771 B4 [0003]

Claims (10)

Torque measuring device ( 10 ), with - a stator ( 12 ), - a rotor ( 14 ), - one on the rotor ( 14 ) torque transducers ( 16 ) for measuring one on the rotor ( 14 ) acting torque and for outputting a torque measurement signal, - a signal generating device ( 28 ) for generating a switching signal from the torque measurement signal, - at least one on the stator ( 12 ) provided primary coil ( 20 ) supplied by a supply voltage source ( 34 ) can be supplied with alternating current, - at least one on the rotor ( 14 ) provided secondary coil ( 22 ), which are used to supply power to the torque transducer ( 16 ) and the signal generator ( 28 ) by a secondary coil voltage of the secondary coil ( 22 ) is provided, wherein the secondary coil voltage from the by the supply voltage source ( 34 ) energized primary coil ( 20 ) in the secondary coil ( 22 ) is induced, - at least one on the rotor ( 14 ) modulation device ( 42 ) for modulating the coil current in the secondary coil ( 22 ), wherein the modulation device ( 42 ) for modulating the coil current according to the switching signal of the latter can be driven, - at least one on the stator ( 12 ) evaluation device ( 46 ), which is set up by modulating the coil current of the secondary coil ( 22 ) in the primary coil ( 20 ) induced coil current modulation to detect. Torque measuring device ( 10 ) according to claim 1, characterized in that the torque-measuring signal is an analog torque-measuring signal. Torque measuring device ( 10 ) according to claim 2, characterized in that the signal generating device ( 28 ) is arranged to generate from the analog torque measurement signal dependent on the temporal waveform of the analog torque measurement signal switching signal. Torque measuring device ( 10 ) according to claim 3, characterized in that the signal generating means 828 ) comprises a digital-to-analog converter for converting the analog torque measurement signal into a temporal waveform-dependent digital switching signal. Torque measuring device ( 10 ) according to claim 3, characterized in that the switching signal is a frequency-modulated by the analog torque measurement signal carrier signal. Torque measuring device ( 10 ) according to claim 3, characterized in that the switching signal is a pulse width modulated by the analog torque measurement signal carrier signal. Torque measuring device ( 10 ) according to one of the preceding claims, characterized in that the modulation device ( 42 ) one on the rotor ( 14 ) provided switching device ( 44 ) for short-circuiting the secondary coil ( 22 ) which is dependent on the switching signal for the time-sequential short-circuiting of the secondary coil ( 22 ) is controllable, wherein the evaluation device ( 46 ), which by the temporally successive short-circuiting in the primary coil ( 20 ) induced coil current modulation to detect. Torque measuring device ( 10 ) according to one of the preceding claims, characterized in that the rotor ( 14 ) is designed in the form of a non-rotatably mounted on a shaft flange. A method of measuring torque, comprising the steps of: (A) measuring a torque applied to a rotor ( 14 (B) generating a switching signal dependent on the time characteristic of the measured torque, (C) modulating a coil current in a secondary coil ( 22 ) according to the switching signal, and (D) detecting by modulating the coil current of the secondary coil ( 22 ) in a primary coil ( 20 ) induced coil current modulation. A method according to claim 9, characterized in that from the coil current modulation detected in step (D), a signal is generated, from which the time profile of the measured torque can be provided by multiplication by a constant factor.

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