Method for operating a drive device for a muscle-powered vehicle and drive device

Abstract

The present invention relates to a method for operating a drive unit (1) for a muscle-powered vehicle. The drive unit (1) comprises a pedal shaft (3) for receiving muscle force, an electric motor (6), and an output shaft (4). The pedal shaft (3) and the electric motor (6) are mechanically connected to the output shaft (4). The method comprises detecting (I) a change in a torque indicator (T1) associated with a torque at the pedal shaft (3). Furthermore, the method comprises controlling (II) the electric motor (6) to provide a torque (TK) such that it counteracts a change in torque (T2) at the output shaft (4) that is associated with the detected change in the torque indicator (T1).

Description

[0001] The present invention relates to a method for operating a drive unit for a muscle-powered vehicle. The muscle-powered vehicle can be a bicycle, for example a pedelec or e-bike. Furthermore, the present invention relates to a control unit for carrying out such a method, and to a drive unit with such a control unit.

[0002] DE 10 2009 029 655 A1 and US 2021 / 0122444 A1 refer to bicycles with an electric drive.

[0003] Bicycles are generally equipped with a pedal crank drive, in which a linear force input is converted into a rotational torque, which serves for propulsion, by means of a crank arm.

[0004] In addition to the described pedal-driven motor, pedelecs also feature an electric motor drive characterized by a uniform torque output and good controllability. Pedal-driven motors known from the prior art result in a non-uniform torque at the rider's pedal and thus also in a non-uniform propulsive force. In driving situations where high resistance must be overcome, such as uphill riding or off-road use, this can have a negative impact. For example, inconsistent propulsive forces can adversely affect traction or energy efficiency. The object of the present invention was therefore to provide a method for operating a drive unit for a muscle-powered vehicle that overcomes the disadvantages of the prior art.

[0005] This problem is solved by the claimed method for operating a drive unit for a muscle-powered vehicle. The muscle-powered vehicle can be a single-track vehicle, for example, a two-wheeler in the form of a pedelec or e-bike. Alternatively, the muscle-powered vehicle can be a multi-track vehicle, for example, a tricycle or a four-wheeled vehicle. The muscle-powered vehicle can also have a different configuration. The drive unit has a pedal shaft to which pedals can be attached to transmit muscle power from the rider to the pedal shaft. Two crank arms, offset by 180°, can be attached to the pedal shaft, each with a pedal mounted on it. When the pedals are operated by the rider, the force can only be applied via half a revolution of the pedal shaft per pedal.The resulting torque at the pedal shaft can build up in a sinusoidal wave from the top dead center of the first pedal and then fall off again at the bottom dead center of the first pedal. Subsequently, the resulting torque at the pedal shaft can build up in a sinusoidal wave from the top dead center of the second pedal and then fall off again at the bottom dead center of the second pedal. With uniform actuation of the crank arms, this results in two sinusoidal harmonics of torque at the pedal shaft over a 360° full rotation of the pedal shaft.

[0006] The drive system comprises an output shaft, which can be coupled to a wheel of the muscle-powered vehicle, for example, a drive wheel, to transmit a driving force from the output shaft to at least one wheel of the vehicle for propulsion. A driven gear, for example, a chainring, can be non-rotatably connected to the output shaft. The driven gear can be mechanically coupled to a wheel of the vehicle, for example, the drive wheel, by means of a continuous recirculating element, for example, a chain. The drive system also includes an electric machine, which can comprise one or more electric motors. Each of the electric motors can have a stator and a rotor, with one stator of the motor being fixed to a housing of the drive system. Some or all of the components of the drive system can be housed in the housing.The housing can be mounted on the vehicle in such a way that it is supported by the vehicle. The housing can be a stationary component that does not move during operation of the drive unit.

[0007] The pedal shaft and the electric motor are mechanically connected to the output of the drive unit. A torque from the pedal shaft can be transmitted to the output via this mechanical connection. Likewise, a torque provided by the electric motor can be transmitted to the output via this mechanical connection. The drive unit can include a superimposed transmission, for example, a planetary gear set, which sums the torques from the pedal shaft and the electric motor and transmits them to the output. The superimposed transmission can be located within the housing.

[0008] The method involves detecting changes in a torque indicator related to a torque applied to the pedal shaft. This detection can involve measuring or calculating the torque indicator. To detect changes in the torque indicator, it is recorded at different times, and the change is determined by comparing the values ​​recorded at these different times. The torque indicator is related to a torque applied to the pedal shaft, for example, a torque applied to the pedal shaft by the driver of a muscle-powered vehicle. For instance, the torque applied to the pedal shaft can be measured directly.In an alternative embodiment, the torque applied to the pedal shaft is detected indirectly by sensing one or more other quantities that are related to the torque on the pedal shaft in a fixed, defined way.

[0009] Furthermore, the method includes controlling the electric machine to provide torque in such a way as to counteract any torque change at the output that would otherwise occur with the detected change in the torque indicator. The drive unit can be designed such that a torque change at the pedal shaft can lead to a torque change at the output of the drive unit. Within the scope of the present invention, the electric machine is controlled in such a way that it provides a torque which counteracts the torque change that would otherwise occur at the output, thus mitigating such a torque change at the output.

[0010] The method of the present invention thus enables the mitigation of torque fluctuations at the output of the drive unit, which can lead to torque fluctuations at the drive wheel of the bicycle and consequently to fluctuations in the bicycle's propulsive force, by controlling the electric motor. As a result, a method for operating a drive unit for a muscle-powered vehicle can be provided that delivers a more uniform torque at the drive wheel and thus a more uniform propulsive force. This has a beneficial effect on the vehicle's traction and energy efficiency.

[0011] In one embodiment, the detection includes sensing an increase in the torque indicator, for example, an increase in the torque applied to the pedal shaft. If such an increase in the torque indicator is detected, the control of the electric machine can include controlling it in such a way that the torque provided by the electric machine is reduced. Alternatively or additionally, the detection can include sensing a decrease in the torque indicator. If such a decrease in the torque indicator is detected, the control of the electric machine can include controlling it in such a way that the torque provided by the electric machine is increased. In both embodiments, the torque applied to the pedal shaft can be summed with the torque provided by the electric machine.By summing the signals, the respective change in the torque indicator can be attenuated. Within the framework of these embodiments, the electric machine can therefore be controlled in such a way that it provides a torque which is opposite to a torque change detected at the pedal shaft.

[0012] In one embodiment, controlling the electric machine includes controlling it such that the torque provided by the electric machine essentially compensates for the torque change at the output shaft that accompanies the detected change in the torque indicator. In other words, the torque change at the pedal shaft is essentially canceled out by a corresponding torque provided by the electric machine, so that there is essentially no torque change at the output shaft of the drive unit. Even if the torque change at the output shaft that accompanies the detected change in the torque indicator is essentially compensated for, a slight change in torque at the output shaft may still occur.However, this change can only be of such a magnitude that, in the present technical field, for example in the field of drive systems for pedelecs, it has no influence on the uniform character of the torque applied to the output and thus to the rider's drive wheel. In one embodiment, the electric machine is controlled in such a way that it provides a torque which completely compensates for the torque change at the output that accompanies the detected change in the torque indicator.

[0013] In one embodiment, the torque indicator detection can involve sensing a sinusoidal torque reading on the pedal shaft over a full 360° rotation of the pedal shaft. In this embodiment, the control mechanism can include controlling the electric motor in such a way that the torque changes at the output shaft associated with the detected changes in the torque indicator are counteracted over the entire pedal shaft rotation. In other words, in this embodiment, the electric motor can provide a sinusoidal torque that is superimposed on the sinusoidal torque applied to the pedal shaft in such a way that the torque fluctuation at the pedal shaft is at least partially compensated by the torque of the electric motor. Thus, the output shaft of the drive unit can provide a substantially constant torque over a full pedal shaft rotation.As a result, a drive system for a muscle-powered vehicle can be provided that delivers a substantially constant torque at the output and therefore also at the drive wheel of the bicycle, regardless of the adjustment angle of the pedal shaft. This results in essentially constant propulsive forces.

[0014] In one embodiment, detecting a change in a torque indicator associated with a torque on the pedal shaft includes processing a measurement signal from the torque indicator. In other words, the detection process involves acquiring a measurement signal from the torque indicator, which is then processed in this embodiment. For example, the detection process may involve measuring over a specific time period, such as a few milliseconds, tenths of a second, or seconds, and the processing may include deriving an average value from the acquired measurement signals over that time period. For example, the average value can be determined by calculating the arithmetic mean of the measurement signals. The average value can also be derived in another way.

[0015] In one embodiment, detecting the change in the torque indicator includes detecting a change in the pedal shaft torque, as described above. Thus, in this embodiment, the torque indicator can be the torque applied to the pedal shaft. The detected torque at the pedal shaft can be processed as described above. The processed version of the detected torque can then be used to control the electric machine within the present method. This embodiment allows for the provision of a substantially constant torque at the output of the drive unit in a particularly accurate, effective, and cost-efficient manner.

[0016] As explained above, the torque indicator can also be measured using one or more other parameters. For example, measuring the change in the torque indicator can include measuring the pedal shaft speed, the power at the pedal shaft, the change in pedal shaft speed, and / or the pedal shaft angle. Alternatively or additionally, measuring the change in the torque indicator can include measuring one or more current values ​​of the electric machine, one or more voltage values ​​of the electric machine, and / or the resulting power output of the electric machine. Alternatively or additionally, measuring the change in the torque indicator can include measuring the vehicle's acceleration, speed, and / or change in vehicle speed.Alternatively or additionally, the detection of the change in the torque indicator can involve detecting the rotational speed of a drive wheel and / or a change in the rotational speed of a drive wheel of the vehicle, whereby the drive wheel can be mechanically connected to the output of the drive unit, for example via a continuous rotating element as described above. One or more other parameters can also be detected to monitor the change in the torque indicator. One, several, or all of these parameters can be used to control the electric machine for the torque compensation described above.In addition, when recording the change in the torque indicator in connection with one, several or all of the quantities described above, a translation depending on a drive concept can be taken into account, for example depending on whether the electric machine is directly connected to the drive or mechanically connected to the pedal shaft.

[0017] The present invention further relates to a control unit that is configured, i.e., specifically prepared, for example, programmed, to execute the method for operating the drive unit of a muscle-powered vehicle according to one of the embodiments described above. The control unit may comprise one or more microprocessors for executing the method, which may be located in the same or different locations. The microprocessors may be networked together via a network, for example, the internet, to execute the method jointly. The control unit may have one or more input and / or output interfaces to communicate with the components of the drive unit in the manner required for executing the method.Regarding the understanding and advantages of the individual features, reference is made to the above explanations in connection with the procedure for operating the drive device.

[0018] Furthermore, the present invention relates to a drive device for a muscle-powered vehicle comprising a pedal shaft for receiving muscle power, an electric motor, an output shaft, and a control device according to the embodiments described above. The pedal shaft and the electric motor are mechanically connected to the output shaft. Regarding the design and advantages of the individual features, reference is made to the above descriptions in connection with the method for operating the drive device. Fig. Figure 1 shows a drive device for a muscle-powered vehicle according to an embodiment of the present invention. Fig. Figure 2 shows a method for operating the drive device from Fig. 1 according to an embodiment of the present invention. Fig. Figure 3 shows torque and propulsive force curves in the Fig. 1 drive device shown, which is operated according to a conventional method. Fig. Figure 4 shows torque and propulsive force curves in the Fig. 1 drive device shown, which according to the in Fig. The procedures shown in section 2 are operated.

[0019] Fig. Figure 1 shows a drive unit 1 for a muscle-powered vehicle according to an embodiment of the present invention. In this embodiment, the muscle-powered vehicle is a bicycle, more precisely a pedelec. The drive unit 1 comprises a housing 2 in which a pedal shaft 3 is rotatably mounted. Pedals 9 are mechanically connected to the pedal shaft 3, and a rider can apply torque to the pedal shaft 3 via these pedals. The pedals 9 are attached to the pedal shaft 3 by means of two crank arms 10 offset by 180° to transmit the torque. Furthermore, the drive unit 1 comprises an output shaft 4, which in this embodiment is non-rotatably connected to a drive gear (not shown), designed as a chainring.The chainring is mechanically connected to a rear wheel hub of the bicycle via a chain, in order to transmit a torque from the output 4 of the drive unit 1 to the rear wheel of the bicycle.

[0020] Furthermore, the drive unit 1 comprises a planetary gear set 5 and an electric motor 6. The electric motor 6 is electrically connected to a battery (not shown), which supplies it with energy to provide torque. The electric motor 6 and the planetary gear set 5 are housed in the casing 2 of the drive unit 1. The pedal shaft 3 and the electric motor 6 are mechanically connected to the output 4 of the drive unit 1 via the planetary gear set 5. Thus, torque applied to the pedal shaft 3 by the cyclist can be transmitted to the output 4 via the planetary gear set 5. Likewise, torque provided by the electric motor 6 can be transmitted to the output 4 via the planetary gear set 5.In the present embodiment, the superimposed transmission 5 is designed such that it sums up the torques of the pedal shaft 3 and the electric machine 6 and supplies them together to the output 4.

[0021] Furthermore, the drive unit 1 includes a sensing device 7 for detecting a torque indicator T1 associated with a torque on the pedal shaft 3. In the present embodiment, the sensing device 7 is configured to detect the torque applied to the pedal shaft 3. Therefore, in the present embodiment, the torque indicator T1 is the torque applied to the pedal shaft 3. The sensing device 7 is configured as a torque sensor to detect the torque applied to the pedal shaft 3. The drive unit 1 includes a control unit 8, which is electronically connected to the sensing device 7 for reading the torque applied to the pedal shaft 3. The control unit 8 is also electronically connected to the electric machine 6 to control or regulate the torque provided by it.

[0022] The control unit 8 is configured to perform the following with reference to Fig. 2 procedures described. The starting point for the procedure is the one described in Fig. The 3 torque and thrust force curves shown in conventional methods for operating a Fig. 1. Drive unit shown 1. In Fig. Figure 3 schematically depicts the torque curve T1 of the pedal shaft 3 as a function of the angular position ω of the pedal shaft 3 when a cyclist applies a torque to the pedal shaft 3 as intended. The upper section also shows the resulting torque curve T2 at the rear wheel of the bicycle as a function of the angular position ω of the pedal shaft 3. The lower section of the Fig. Figure 3 shows the resulting propulsive force V of the bicycle as a function of the angular position ω of the pedal shaft 3. Also shown in Fig. Figure 3 represents an angular position ω of the pedal shaft 3 at a starting point ω1 of a complete pedal shaft revolution, at which a pedal 9 of the pedal shaft 3 is located at top dead center. Furthermore, the angular position ω2 is shown, at which the same pedal 9 is again at top dead center after completing a full pedal shaft revolution of 360°.

[0023] As from Fig. As can be seen in Figure 3, in conventional drive systems 1 for pedelecs, the force application can only be initiated via half a revolution per crank arm 10 when operated by the rider. The resulting torque T1 on the pedal shaft 3 builds up in a sinusoidal wave from the top dead center of the first pedal 9, then drops again to its bottom dead center. Subsequently, the torque T1 on the pedal shaft 3 builds up again in a sinusoidal wave when the second pedal 9, which is offset by 180° relative to the first pedal 9, is actuated from its top dead center, and then drops again to its bottom dead center. With both pedals 9 being actuated simultaneously, this results in two sinusoidal harmonics in the torque on the pedal shaft 3 over a 360° full revolution of the pedal shaft 3, as shown in Figure 3. Fig. 3 shown. Consequently, the torque T1 experiences a near-zero crossing twice during a full revolution. As shown Fig. As can be seen in Figure 3, this non-uniform torque characteristic T1 of the pedal shaft 3 is also reflected in the torque T2 of the rear wheel of the bicycle, which in turn correlates linearly with the torque at the output 4 of the drive unit 1. Consequently, the propulsive force V of the bicycle also exhibits a corresponding non-uniform characteristic, as shown in the lower section of Figure 3. Fig. 3 visible.

[0024] These disadvantages are eliminated by the method for operating the drive unit 1. Fig. 1 of the present invention. The torque and thrust force curves T1, T2 and V resulting from the method of the present invention when the drive device 1 is actuated by the driver, which are described above in conjunction with Fig. The activity described in section 3 corresponds to the following: Fig. 4 shown. Fig. 4 is like Fig. 3. In a first step I of the method of the present invention, the control device 8 detects, via the detection device 7, a change, i.e., an increase or decrease, of the torque T1 applied to the pedal shaft 3, which has a profile as described above in conjunction with Fig. 3 has the described torque T1. Referring to Fig. 4. For example, an increase in the torque T1 of the pedal shaft 3 can be detected here, which occurs as described above when a pedal 9 is actuated by the rider from its top dead center. As described above, such an increase can occur, for example, from a rotational angular position ω1 of the pedal shaft 3.

[0025] In the present embodiment, the torque indicator, i.e., the torque T1 applied to the pedal shaft 3, is recorded and processed in step I over a specific period of time by calculating an average value of the recorded torque over that period. If a change, i.e., an increase or decrease, of the torque indicator T1 is detected in step I, the process proceeds to step II.

[0026] In step II, the change in the torque indicator T1 detected in step I is used to control the electric machine 6. More precisely, in step II, the electric machine 6 is controlled to provide a torque TK such that it counteracts the torque change T2 at the rear wheel or at the output 4 that accompanies the change in the torque indicator T1 detected in step I. In other words, the electric machine 6 is controlled to provide a torque TK that essentially compensates for the change in torque T1 at the pedal shaft 3 detected in step I. Consequently, in the method of the present invention, the change in torque T1 at the pedal shaft 3 is not reflected in the torque T2 at the output 4 of the drive unit 1 and therefore not in the propulsive force V.Instead, the change in torque T1 of the pedal shaft 3 is compensated by an opposing change in torque TK of the electric machine 6. The procedure then returns to step I.

[0027] In the present embodiment, the detection I of the torque indicator T1 comprises detecting a change in this torque indicator over a complete revolution of the pedal shaft 3. The control II of the electric machine 6 comprises controlling this electric machine 6 such that the torque changes T2 at the output 4 associated with the detected changes in the torque indicator T1 are counteracted over a complete revolution of the pedal shaft 3. As a result, the output 4 can provide a substantially constant torque T2 over a complete revolution of the pedal shaft 3, as shown in Fig. Figure 4 shows that, consequently, a substantially constant propulsive force V of the bicycle can be provided over a complete revolution of the pedal shaft 3. The detection and control can be carried out in partial steps, with each detection step I being followed by a control step II in a sequential, loop-like manner, as shown in Figure 4. Fig. 2 is shown. Reference sign 1 Drive unit 2 cases 3 Pedal shaft 4 Drive 5 superimposed gear units 6 Electric Machine 7. Recording device 8 Control unit 9 pedals 10 crank arms I Capture change torque indicator II Controlling an electric machine T torque V Feed force ω Pedal wave angle ω1 Start of full rotation ω2 End of complete revolution T1 Torque Pedal Shaft T2 torque output TK torque electric machine

Claims

[1] Method for operating a drive device (1) for a muscle-powered vehicle, wherein the drive device (1) has a pedal shaft (3) for absorbing muscle power, an electric machine (6) and an output (4), wherein the pedal shaft (3) and the electric machine (6) are mechanically operatively connected to the output (4), comprising detecting (I) a change in a torque indicator (T1) associated with a torque on the pedal shaft (3) by detecting the torque indicator (T1) at different times and by comparing the values detected at different times, and controlling (II) the electric machine (6) to provide a torque (TK) in such a way that it counteracts a torque change (T2) at the output (4) associated with the detected change in the torque indicator (T1). [2] Method according to claim 1, characterized bythat the detection (I) comprises detecting an increase in the torque indicator (T1) and the control (II) of the electric machine (6) comprises controlling such that the torque (TK) provided by the electric machine (6) is reduced. [3] Method according to claim 1 or 2, characterized by that the detection (I) comprises detecting a reduction in the torque indicator (T1) and the control (II) of the electric machine (6) comprises controlling such that the torque (TK) provided by the electric machine (6) is increased. [4] Method according to one of the preceding claims, characterized by that the actuation (II) of the electric machine (6) comprises actuation such that the torque (TK) provided by the electric machine (6) substantially compensates for the torque change (T2) at the output (4) associated with the detected change in the torque indicator (T1). [5] Method according to one of the preceding claims, characterized by that the detection (I) comprises detecting a sinusoidal torque indicator (T1) over a complete pedal shaft revolution and the control (II) comprises controlling the electric machine (6) in such a way that the torque changes (T2) at the output (4) associated with the detected changes in the torque indicator (T1) are counteracted over the complete pedal shaft revolution, so that the output (4) provides a substantially constant torque (T2) over a complete pedal shaft revolution. [6] Method according to one of the preceding claims, characterized by that the detection (I) comprises processing a measurement signal of the torque indicator (T1). [7] Method according to one of the preceding claims, characterized by that detecting (I) the change in the torque indicator (T1) comprises detecting a change in the pedal shaft torque. [8] Method according to one of the preceding claims, characterized by in that the detection (I) of the change in the torque indicator (T1) comprises detecting at least one of a rotational speed of the pedal shaft (3), a power at the pedal shaft (3), a change in the speed of the pedal shaft (3), a rotational angle of the pedal shaft (3), a current value of the electric machine (6), a voltage value of the electric machine (6), a resulting power of the electric machine (6), an acceleration value of the vehicle, a speed of the vehicle, a change in the speed of the vehicle, rotational speed information of a drive wheel of the vehicle that is mechanically operatively connected to the output (4), and a change in the speed of a drive wheel of the vehicle that is mechanically operatively connected to the output (4). [9] Control device (8) arranged to carry out the method according to one of the preceding claims. [10] Drive device (1) for a muscle-powered vehicle with a pedal shaft (3) for absorbing muscle power, an electric machine (6), an output (4) and a control device (8) according to claim 9, wherein the pedal shaft (3) and the electric machine (6) are mechanically operatively connected to the output (4).

Images