Torque sensor unit for an e-bike

Abstract

The invention relates to a torque sensor unit (100) comprising a movable first sensor part (10) and a stationary second sensor part (20) fed by a supply voltage (V_SUP). The first sensor part (10) and the second sensor part (20) are electromagnetically coupled. Electromagnetic signal transmission from the first sensor part (10) to the second sensor part (20) induces a modulated measuring voltage (V_MOD) at an output (22) of the second sensor part (20). The torque sensor unit (100) also comprises a circuit (30) which is coupled to the output (22) of the second sensor part (20) and is designed to output, on the basis of the modulated measuring voltage (V_MOD), an output signal (TORQ) which is indicative of a torque at the first sensor part (10). In addition, the circuit (30) is also coupled to the supply voltage (V_SUP) and designed to output the output signal (TORQ) on the basis of both the modulated measuring voltage (V_MOD) and the supply voltage (V_SUP).

Description

Torque sensor unit for an e-bike TECHNICAL FIELD [1] This document relates to embodiments of a torque sensor unit, in particular for an electric drive device of a bicycle, as well as corresponding embodiments of a method for measuring a torque using a torque sensor unit. Furthermore, this document relates to embodiments of an electric drive device comprising a torque sensor unit and to embodiments of a bicycle comprising an electric drive device. BACKGROUND [2] Bicycles are increasingly being equipped with electric drive systems to make pedaling easier for riders. Such bicycles are commonly referred to as e-bikes or pedelecs, which also include derivatives such as cargo bikes, recumbent bikes, and the like. [3] The control of the electric drive device is based on various control parameters, e.g. a parameter whose value is indicative of the current torque generated by the cyclist on the pedal. [4] If the control of the electric drive device is based on the actual torque (generated by the cyclist on the pedal), an accurate measurement of the corresponding parameter should be carried out, i.e., in particular, that the same parameter value is always assigned to the same actual torque, regardless of any disturbing influences. [5] There are a variety of different types of sensors for measuring torque, for example, those that measure the torque based on an electromagnetic coupling between a moving part and a stationary part. [6] The technical problem underlying the present invention is to propose a torque sensor unit based on electromagnetic coupling that allows the torque to be measured with the least possible interference. SUMMARY [7] The aforementioned technical problem is solved by the subject matter of the independent claims. Features of advantageous embodiments are specified in the subclaims. [8] According to a first aspect, a torque sensor unit comprises a movably arranged first sensor part and a stationary second sensor part fed by a supply voltage. The first sensor part and the second sensor part are electromagnetically coupled. An electromagnetic signal transmission from the first sensor part to the second sensor part induces a modulated measuring voltage at an output of the second sensor part. The torque sensor unit further comprises a circuit coupled to the output of the second sensor part, which is designed to output an output signal indicative of a torque at the first sensor part as a function of the modulated measuring voltage. In addition, the circuit is additionally coupled to the supply voltage and is designed to output the output signal as a function of both the modulated measuring voltage and the supply voltage. [9] According to a second aspect, a method for measuring a torque using a torque sensor unit is proposed. The torque sensor unit comprises a movably arranged first sensor part and a stationary second sensor part powered by a supply voltage. The first sensor part and the second sensor part are electromagnetically coupled. An electromagnetic signal transmission from the first sensor part to the second sensor part induces a modulated measuring voltage at an output of the second sensor part. The measuring method comprises outputting an output signal indicative of a torque at the first sensor part as a function of both the modulated measuring voltage and the supply voltage.

[0010] Further aspects relate to an electric drive device for a bicycle comprising a torque sensor unit according to the first aspect and to a corresponding bicycle.

[0011] Some embodiments are described below. The features of these embodiments may be combined to form further embodiments, unless expressly stated otherwise.

[0012] The electromagnetic coupling between the first sensor part and the second sensor part eliminates the need for wires or slip rings. In some embodiments, the two sensor parts are oriented such that relative movement (such as a rotation) has no effect on the electromagnetic coupling.

[0013] Due to the electromagnetic coupling between the first sensor part and the second sensor part, wireless signal transmission between the first sensor part and the second sensor part is possible and, in some embodiments, also provided. The first sensor part comprises, for example, a switch that operates at a switching frequency dependent on a torque-dependent value measured there. These switching operations can lead to a corresponding electromagnetic signal transmission from the first sensor part to the second sensor part and thus induce said modulated measurement voltage.

[0014] The modulated measurement voltage corresponds, for example, to a differential voltage between the supply voltage and a sensor voltage drop in the second sensor section. Fluctuations in the supply voltage can therefore also lead to fluctuations in the modulated measurement voltage. However, such fluctuations in the modulated measurement voltage are not attributable to corresponding changes in torque and would therefore lead to measurement errors. Therefore, the circuit generates the output signal while also taking the supply voltage into account, ensuring, for example, that the fluctuations in the modulated measurement voltage induced by fluctuations in the supply voltage are not reflected in the output signal. The following example explains which circuit implementation is suitable for this purpose.

[0015] According to one embodiment, the circuit comprises a first operational amplifier with a first input, a second input, and an output. The first input is coupled to the supply voltage. The second input is coupled to the modulated measurement voltage. The output is fed back to the first input, for example, via a resistor.

[0016] For example, the torque sensor unit further comprises a first filter circuit, wherein the first input is coupled to the supply voltage via the first filter circuit. The first filter circuit can be configured as a low-pass filter.

[0017] For example, the torque sensor unit further comprises a second filter circuit, wherein the second input is coupled to the modulated measurement voltage via the second filter circuit. The second filter circuit can also be configured as a low-pass filter.

[0018] In particular, the first operational amplifier can be configured as a subtractor or as a differential amplifier. For example, the first input of the first operational amplifier is inverting and the second input of the first operational amplifier is non-inverting.

[0019] According to a further embodiment, the circuit comprises a second operational amplifier with a first input, a second input, and an output. For example, the first input and the second input are coupled to the output of the first operational amplifier via a third filter circuit. The output signal is provided at the output of the second operational amplifier.

[0020] In one embodiment, the circuit is designed to disregard changes in the modulated measurement voltage induced by fluctuations in the supply voltage when generating the output signal. This suppression of influences caused by fluctuations in the supply voltage is achieved, for example, on the basis of the above-explained interconnection of the two operational amplifiers. The fluctuations in the supply voltage can arise, for example, when another load is also coupled to the supply voltage, resulting in an at least temporary voltage drop due to the corresponding power consumption. Such a voltage drop also induces a change in the modulated measurement voltage, which However, this is not due to a corresponding change in torque and could therefore lead to incorrect measurement results. According to the above embodiments, this can be avoided because changes in the modulated measurement voltage induced by fluctuations in the supply voltage are not taken into account when generating the output signal.

[0021] Also proposed here is an electric drive device for a bicycle, which comprises a torque sensor unit according to one of the preceding embodiments. The electric drive device is designed, for example, as an e-bike drive, e.g., as a mid-engine. The central placement between the front and rear wheels contributes to stability and safety. For example, the first sensor part of the torque sensor unit is arranged on a drive axle, e.g., on a shaft of the electric drive device. Alternatively, the first sensor part can also be arranged in a pedal, on the crank, or in the chainring.

[0022] The electric drive device comprises, for example, a control unit for controlling the electric drive device, wherein the control unit receives the output signal of the torque sensor unit and controls the electric drive device based on the output signal.

[0023] Finally, a bicycle is proposed that includes an electric drive device as described above. Using the torque sensor unit, a control unit detects, for example, the torque currently generated by the cyclist on the pedals and, based on this, controls, for example, a correspondingly adjusted power output of the electric drive device.

[0024] A bicycle battery, for example, provides the aforementioned supply voltage. For measurement and / or signal transmission purposes, the first sensor component can include its own battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings show:

[0026] Fig. 1 shows a schematic and exemplary block diagram of a Torque sensor unit according to one or more embodiments; and

[0027] Fig. 2 shows schematically and exemplarily a circuit diagram of a Circuit of a torque sensor unit according to one or more embodiments. DETAILED DESCRIPTION

[0028] Fig. 1 shows schematically and exemplarily a block diagram of a torque sensor unit 100 according to one or more embodiments.

[0029] The torque sensor unit 100 comprises a movably arranged first sensor part 10 and a stationary second sensor part 20 fed by a supply voltage V_SUP (of, for example, 12 V).

[0030] The first sensor part 10 and the second sensor part 20 are electromagnetically coupled. This coupling is illustrated in Fig. 1 by the two coil elements. In fact, the second sensor part 20 can have a coil 23 energized by the supply voltage V SUP . The first sensor part 10 can also have a coil 13 or can interact electromagnetically with the second sensor part 20 in some other way.

[0031] The first sensor part 10 and the second sensor part 10 are electromagnetically coupled. An electromagnetic signal transmission from the first sensor part 10 to the second sensor part 20 induces a modulated measuring voltage V MOD at an output of the second sensor part 20. Due to the signal transmission from the first sensor part 10 to the second sensor part 20 (e.g. resulting from the application of a torque), the measuring voltage V MOD is, for example, pulse width modulated. The first sensor part 10 comprises, for example, a switch (not shown here) which is operated at a switching frequency dependent on a value measured there (which depends, for example, on the torque). These switching operations can lead to a corresponding electromagnetic signal transmission from the first sensor part 10 to the second sensor part 20 and thus induce said modulated measuring voltage.

[0032] The second sensor part 20 receives the supply voltage V_SUP, for example, via an input 21. A capacitor C3, for example, is connected between input 21 and output 22 of the second sensor part 20, for example in parallel with the coil 23.

[0033] The output 22 can be connected to ground via a switch S1 that can be operated by a control unit.

[0034] The torque sensor unit 100 further comprises a circuit 30 coupled to the output 22 of the second sensor part 20, which is configured to output an output signal TORQ as a function of the modulated measurement voltage V MOD , which is indicative of a torque at the first sensor part 10. Furthermore, the circuit 30 is additionally coupled to the supply voltage V SUP and is configured to output the output signal TORQ as a function of both the modulated measurement voltage V MOD and the supply voltage V SUP .

[0035] The modulated measurement voltage V MOD corresponds, for example, to a differential voltage between the supply voltage V SUP and a sensor voltage V SENS falling in the second sensor part 20. Thus, not only changes in the sensor voltage V SENS induced by the signal transmission from the first sensor part 10 to the second sensor part 20 lead to changes in the modulated measurement voltage V MOD, but also fluctuations in the supply voltage V SUP.

[0036] Fluctuations in the supply voltage V SUP can occur, for example, if another load 200 is also coupled to the supply voltage V_SUP and, due to the corresponding power consumption, an at least temporary voltage drop occurs. The additional load 200 is, for example, a bicycle headlight, a bicycle brake light, and / or a cell phone charger. The control unit or subunits of the control unit of the electric drive device can also form such an additional load 200.

[0037] For example, the additional load 200 can be represented as a parallel circuit comprising a capacitor C4 and an ohmic resistor RI. When the additional load 200 is supplied with the supply voltage V SUP, for example by actuating a switch S2, the capacitor C4 is charged. The resulting Current consumption may lead to a temporary reduction of the supply voltage V SUP, which is reflected in a corresponding change of the modulated measuring voltage V MOD knocks down.

[0038] Even with additional stabilization by an optionally provided voltage regulator 300, fluctuations in the supply voltage V SUP cannot be excluded, which may cause a corresponding change in the modulated measuring voltage V MOD would cause.

[0039] Such fluctuations in the modulated measuring voltage V MOD are therefore not attributable to corresponding changes in the torque or corresponding signal transmissions from the first sensor part 10 to the second sensor part 20 and would accordingly lead to measurement errors.

[0040] Therefore, it is provided here that the circuit 30 generates the output signal TORQ with additional consideration of the supply voltage V SUP and, for example, ensures that the voltage fluctuations in the supply voltage V SUP induced fluctuations of the modulated measuring voltage V MOD are not reflected in the output signal TORQ.

[0041] This not only enables a more robust and accurate torque measurement, but also a less complex circuit, e.g. the elimination of the voltage regulator 300 or at least another voltage regulator for the voltage V SUP supplied to the torque sensor unit.

[0042] In the following, with additional reference to Fig. 2, a suitable embodiment of a circuit implementation is explained by way of example.

[0043] The circuit 30 comprises a first operational amplifier 31 with a first input 311, a second input 312 and an output 313.

[0044] The first operational amplifier 31 is configured as a subtractor or differential amplifier. The output 313 is fed back to the first input 311, for example, via a resistor 315. Furthermore, the first input 311 of the first operational amplifier 31 is inverting, and the second input 312 of the first operational amplifier 31 is non-inverting.

[0045] The first input 311 is coupled to the supply voltage V SUP via a first filter circuit 33. The second input 312 is coupled to the modulated measurement voltage V MOD via a second filter circuit 34.

[0046] Due to this connection, the change in the modulated measurement voltage V MOD induced by fluctuations in the supply voltage V SUP is subtracted from the output signal at output 313. This means that such changes in the modulated measurement voltage V MOD are not reflected in the output signal TORQ.

[0047] The first filter circuit 33 is configured as a low-pass filter. It includes resistors 331, 332, 333, and capacitor 336, connected as shown in Fig. 2.

[0048] The second filter circuit 34 can also be configured as a low-pass filter.

[0049] The second filter circuit 34 receives the modulated measurement voltage V MOD via a diode 341. The correspondingly rectified voltage is fed to the second input 312 of the first operational amplifier 31 via an RC network comprising resistors 341, 342, 343, and capacitor 346. The capacitor 346 and diode 347 form, for example, a so-called peak detector. The two resistors 341 and 342 form a voltage divider, so that the voltage supplied to the first operational amplifier 31 is limited in magnitude.

[0050] The second input 312 is also connected to ground via a resistor network 37 comprising resistors 371, 372, and 373. Resistor 373 can be connected to a defined voltage (to which, for example, the first operational amplifier 31 is also connected), so that even in the absence of an input signal, no undefined states arise (Fig. 2 does not show the corresponding voltage source).

[0051] The circuit 30 further comprises a second operational amplifier 32 having a first input 321, a second input 322 and an output 323. There, the first input 321 and the second input 322 are coupled to the output 313 of the first operational amplifier 31 via a third filter circuit 35.

[0052] The first input 321 of the second operational amplifier 32 is, for example, non-inverting and is connected to the output of the first operational amplifier 31 via a first RC element 351, 352 of the third filter circuit 35.

[0053] The second input 322 of the second operational amplifier 32 is, for example, inverting and is connected to the output of the first operational amplifier 31 via a second RC element 356, 357 of the third filter circuit 35.

[0054] The non-feedback output 323 of the second operational amplifier 32 is connected to ground, for example, via a resistor 325. The output signal TORQ is provided at the output of the second operational amplifier 32. The second operational amplifier 32 is designed, for example, as a comparator.

[0055] As explained in the introduction, the circuit 30 is designed to disregard changes in the modulated measuring voltage V MOD induced by fluctuations in the supply voltage V SUP when generating the output signal TORQ.

[0056] This suppression of influences due to fluctuations in the supply voltage V SUP is achieved, for example, based on the circuitry of the first operational amplifier 31 explained with reference to Fig. 2. The circuit section connected downstream of this, comprising the second operational amplifier 32 and the third filter circuit 35, performs, for example, an analog-to-digital conversion, so that the output signal TORQ can be provided as a digital output signal, according to some embodiments. The digital output signal can then be detected by the control unit and used as the basis for corresponding control processes.

[0057] As described in the introduction, the torque sensor unit 100 is particularly suitable for use in an electric drive device (not shown in the drawing here) for a bicycle (also not shown in the drawing here). The electric drive device is designed, for example, as an e-bike drive, e.g., as a mid-engine. For example, the first sensor part 10 of the torque sensor unit 100 is arranged on a drive axle, e.g., on a shaft of the electric drive device. Alternatively, the first sensor part 10 can also be arranged in a pedal, on the crank, or in the chainring.

[0058] The electric drive device comprises, for example, a control unit for controlling the electric drive device, wherein the control unit receives the output signal TORQ of the torque sensor unit 100 and controls the electric drive device based on the output signal.

[0059] Using the torque sensor unit, a control unit detects, for example, the torque currently generated by the cyclist on the pedal and, based on this, controls, for example, a correspondingly adjusted power output of the electric drive device.

Claims

CLAIMS 1. Torque sensor unit (100), comprising: a movably arranged first sensor part (10); a stationary second sensor part (20) fed by a supply voltage (V_SUP), wherein o the first sensor part (10) and the second sensor part (20) are electromagnetically coupled, and o an electromagnetic signal transmission from the first sensor part (10) to the second sensor part (20) induces a modulated measurement voltage (V_MOD) at an output (22) of the second sensor part (20); a circuit (30) coupled to the output (22) of the second sensor part (20) and designed to output an output signal (TORQ) indicative of a torque at the first sensor part (10) as a function of the modulated measurement voltage (V_MOD);characterized in that the circuit (30) is additionally coupled to the supply voltage (V SUP) and is designed to output the output signal (TORQ) as a function of both the modulated measurement voltage (V MOD) and the supply voltage (V_SUP); 2. Torque sensor unit (100) according to claim 1, wherein the circuit (30) comprises a first operational amplifier (31) having a first input (311), a second input (312) and an output (313), wherein the first input (311) is coupled to the supply voltage (V SUP); the second input (312) is coupled to the modulated measurement voltage (V MOD); and the output (313) is fed back to the first input (311).

3. Torque sensor unit (100) according to claim 2, further comprising a first filter circuit (33), wherein the first input (31) is coupled to the supply voltage (V SUP) via the first filter circuit (33).

4. Torque sensor unit (100) according to claim 2 or 3, further comprising a second filter circuit (34), wherein the second input (312) is coupled to the modulated measurement voltage (V MOD ) via the second filter circuit (34).

5. The torque sensor unit (100) according to claim 3, wherein the first filter circuit (33) is configured as a low-pass filter.

6. Torque sensor unit (100) according to one of the preceding claims 2 to 5, wherein the first operational amplifier (31) is configured as a differential amplifier.

7. Torque sensor unit (100) according to one of the preceding claims 2 to 6, wherein the first input (311) of the first operational amplifier (31) is inverting and the second input (312) of the first operational amplifier (31) is non-inverting.

8. Torque sensor unit (100) according to one of the preceding claims 2 to 7, wherein the circuit (30) comprises a second operational amplifier (32) having a first input (321), a second input (322) and an output (323), wherein the first input (321) and the second input (322) are coupled to the output (313) of the first operational amplifier (31) via a third filter circuit (35); the output (323) of the second operational amplifier (32) provides the output signal (TORQ).

9. Torque sensor unit (100) according to one of the preceding claims, wherein the circuit (30) is designed to disregard changes in the modulated measuring voltage (V MOD) induced by fluctuations in the supply voltage (V SUP) when generating the output signal (TORQ).

10. Torque sensor unit (100) according to one of the preceding claims, wherein the modulated measuring voltage (V MOD) corresponds to a differential voltage between the supply voltage (V SUP) and a sensor voltage (V_SENS) dropping in the second sensor part (20).

11. An electric drive device for a bicycle, comprising a torque sensor unit (100) according to any one of the preceding claims.

12. Electric drive device according to claim 11, wherein the first sensor part (10) is arranged on a drive axle of the electric drive device.

13. Electric drive device according to claim 11 or 12, comprising a control unit for controlling the electric drive device, wherein the control unit receives the output signal (TORQ) of the torque sensor unit (100) and controls the electric drive device based on the output signal (TORQ).

14. A bicycle comprising an electric drive device according to any one of claims 11 to 14.

15. A method for measuring a torque by means of a torque sensor unit (100), wherein the torque sensor unit (100) comprises: a movably arranged first sensor part (10); a stationary second sensor part (20) fed by a supply voltage (V_SUP), wherein o the first sensor part (10) and the second sensor part (20) are electromagnetically coupled, and o an electromagnetic signal transmission from the first sensor part (10) to the second sensor part (20) induces a modulated measuring voltage (V_MOD) at an output (22) of the second sensor part (20); wherein the method is characterized by: Outputting an output signal (TORQ) indicative of a torque at the first sensor part (10) as a function of both the modulated measuring voltage (V_M0D) and the supply voltage (V_SUP).

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