METHOD FOR OPERATING A DRIVE UNIT OF AN ELECTRIC BICYCLE

Description

State of the art

[0001] The present invention relates to a method for operating a drive unit of an electric bicycle, and to an electric bicycle.

[0002] Electric bicycles are known for their drive units, which assist the rider's pedaling with motor power. Typically, this motor assistance only occurs when the rider is applying a certain amount of pedaling torque, meaning only while pedaling. When the rider stops pedaling, the motor's output is either designed or required by law. Often, the motor's output is regulated based on the rider's pedaling torque, which is detected by sensors. Fluctuations in rider pedaling torque can vary considerably, leading to significant fluctuations in the motor's output and potentially negatively impacting riding comfort.For example, reference is made to the publication US 2022 / 135176 A1. Disclosure of the invention

[0003] The invention relates to a method with the features of claim 1 or 9, and to an electric bicycle according to claim 10. Advantageous further developments are set forth in the dependent claims.

[0004] The method according to the invention with the features of claim 1 is characterized in that a simple and cost-effective way can be provided for the precise regulation or control of a drive torque of a drive unit of an electric bicycle, which allows for a particularly high level of riding comfort for a rider of the electric bicycle.

[0005] The driver torque signal is defined in particular as a value of the driver torque currently generated by the driver, which is preferably detected by means of a torque sensor. Alternatively, and preferably, the driver torque signal can be any signal or piece of information that represents the generated driver torque and thus, in particular, reflects a driver request for motor assistance from the drive unit.

[0006] Preferably, the second filtering of the driver torque signal using the second low-pass filter takes place after the first filtering of the driver torque signal using the first low-pass filter.

[0007] Particularly preferred in the controlled generation of the motor torque is the control of the drive unit in such a way that the generated motor torque is directly proportional to the driver torque signal filtered by means of the second low-pass filter.

[0008] In other words, the system controls the motor torque generated by the drive unit based on a driver torque signal filtered by two separate low-pass filters. This allows for particularly flexible control of the drive unit to provide the optimal motor torque for maximum driving comfort. Specifically, torque fluctuations in the driver torque can be effectively filtered out when needed, resulting in a particularly smooth motor torque curve. This prevents, for example, any "wobbling" of the motor assistance. Furthermore, in other situations, the system can provide highly responsive motor assistance from the drive unit, meaning a rapid and direct response to the driver's input.This is achieved by using two separate low-pass filters to provide particularly high flexibility in filtering the driver torque signal. In particular, at least one of the two low-pass filters can be adaptive to allow optimal adjustment to the respective driving situations during operation.

[0009] The dependent claims describe preferred embodiments of the invention.

[0010] Preferably, the second low-pass filter has a variable time constant. During the execution of the method, the variable time constant is adjusted depending on the driver torque signal. In other words, the variable time constant of the low-pass filter is actively adapted to the current shape of the driver torque signal. For example, the variable time constant can be increased to smooth the driver torque signal more effectively. Alternatively, the variable time constant can be reduced to smooth the driver torque signal less effectively and thus provide greater responsiveness from the drive system.

[0011] Particularly preferably, the method further includes the step of determining the difference in the driver torque signal between an input and an output of the second low-pass filter. The variable time constant of the second low-pass filter is adjusted depending on the determined difference. That is, the values ​​of the driver torque signal present at the input and output of the second low-pass filter are subtracted from each other to calculate the difference. The variable time constant of the second low-pass filter is then adjusted depending on the magnitude of this difference. This allows for a particularly simple adaptation of the filtering.

[0012] Preferably, the variable time constant of the second low-pass filter is increased as the difference decreases. For example, a decreasing difference can be determined by recording the differences over a predetermined period. Alternatively, and more preferably, a gradient of the differences can be determined, and a decrease in the differences can be observed based on this gradient.

[0013] Based on the determined decreasing difference, or alternatively based on a low instantaneous value of the difference, a constant, uniform driving situation can be inferred. In this case, for example, low drive system responsiveness is required. Thus, a strong smoothing of the driver torque signal can be implemented to prevent unwanted fluctuations in engine torque and thereby provide a particularly high level of driving comfort.

[0014] Preferably, the variable time constant of the second low-pass filter is reduced when an increasing difference is detected. For example, an increasing difference can be determined by recording the differences over a predetermined period. Alternatively, preferably, a gradient of the differences can be determined, and an increase in the differences can be observed based on this gradient. Based on the detected increasing difference, or alternatively, based on a high instantaneous value of the difference, a dynamic driving situation, such as a technically demanding driving situation, can be inferred. In this case, for example, high responsiveness of the drive system is desirable. By reducing the variable time constant of the second low-pass filter, the filtering effect of the second low-pass filter is reduced or completely deactivated. For example, the variable time constant can be set to zero.This allows for a particularly direct and rapid conversion of the driver's request into engine torque.

[0015] Preferably, the variable time constant of the second low-pass filter is reduced to a value equal to or below a predetermined threshold time constant when the measured difference is greater than or equal to a predetermined threshold difference. This allows for high drive responsiveness, analogous to the method described above. Alternatively, or more preferably, the variable time constant of the second low-pass filter is increased to a value greater than the predetermined threshold time constant when the measured difference is less than the predetermined threshold difference. This also allows for an operating mode of the drive unit, analogous to the method described above, in which strong filtering is implemented to prevent undesirable torque fluctuations in the motor torque. Furthermore, the method can be carried out reliably and accurately in a particularly simple manner.

[0016] Preferably, determining the driver torque signal includes the step of recording the driver torque signal over a predetermined time period. During this process, the variable time constant of the second low-pass filter is adjusted based on the recorded driver torque signal. For example, the driver torque signal can be recorded over a period of five seconds. This allows for further simplification of the procedure and even more precise adjustment of driving comfort.

[0017] Preferably, the method further comprises the step of determining a maximum value of the recorded driver torque signal, particularly within a predetermined time period. The variable time constant of the second low-pass filter is then adjusted based on this maximum value. This allows the method to be carried out in a particularly simple and cost-effective manner.

[0018] Particularly preferably, the method further comprises the step of multiplying the driver torque signal by a support factor. The controlled generation of the motor torque is then achieved using the driver torque signal multiplied by the support factor. The support factor can, for example, be a predetermined constant value. Alternatively, and preferably, the support factor can be variable, i.e., adaptive, and adjusted, for example, depending on the magnitude of the driver torque signal. This allows the control of the drive unit to be carried out in a particularly simple manner.

[0019] The multiplication of the driver torque signal preferably occurs before the second filtering, in particular between the first filtering using the first low-pass filter and the second filtering using the second low-pass filter. That is, the driver torque signal, already multiplied by the support factor, is filtered by the second filter.

[0020] Alternatively, and preferably, the driver torque signal is multiplied after the second filtering. In this case, the first and second filtering preferably occur immediately one after the other.

[0021] Preferably, the first low-pass filter has a predetermined first time constant that has a constant value. This makes the process particularly simple and cost-effective, while providing optimal processing of the driver torque signal to enable the highest possible driving comfort.

[0022] Furthermore, the invention leads to an electric bicycle comprising a drive unit, which is specifically configured to generate motor torque to assist the rider's muscle power, and a control unit. The control unit is configured to actuate the drive unit in a controlled manner. The control unit is also configured to carry out the described method. Brief description of the drawings

[0023] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: Figure 1 is a simplified schematic view of an electric bicycle in which a method for operating a drive unit of the electric bicycle according to a first embodiment of the invention is carried out, Figure 2 is a simplified representation of an exemplary time-dependent torque curve in which the method according to the first embodiment is carried out, Figure 3 is a simplified representation of an implementation of the method according to the first embodiment, and Figure 4 is a simplified representation of an implementation of a method according to a second embodiment of the invention. Embodiments of the invention

[0024] Figure 1Figure 1 shows a simplified schematic view of an electric bicycle 100. The electric bicycle 100 comprises a drive unit 102, which is designed as an electric motor. The drive unit 102 is arranged in the area of ​​a bottom bracket 108 of the electric bicycle 100 and is designed to assist a manual pedaling force applied by a rider of the electric bicycle 100 via a crank mechanism 104 by means of an electrically generated torque.

[0025] Furthermore, the electric bicycle 100 includes an electrical energy storage device 109, by means of which the drive unit 102 can be supplied with electrical energy. A control unit 103 is also integrated into the drive unit 102.

[0026] The control unit 103 is configured to actuate the drive unit 102 in response to pedaling by the rider of the electric bicycle 100. Specifically, the drive unit 102 is controlled such that, depending on the rider's muscle power, a motor torque is generated to provide motor assistance to the rider while pedaling. The generation of the motor torque is controlled according to the magnitude of the rider's torque.

[0027] The control unit 103 is configured to carry out a procedure for operating the drive unit 102. Using this procedure, the drive unit 102 can be optimally actuated depending on the rider's torque during operation, i.e., particularly during the movement of the electric bicycle 100.

[0028] The procedure is described below in relation to the Figures 2 to 4described in detail Figure 2 Figure 1 shows an example view of a torque recording 60, which can be recorded during a ride on the electric bicycle 100. The rider torque 62 is shown as a function of time 61. The rider torque 62 can be measured using a torque sensor 107 (see Figure 107). Figure 1 ) are recorded. In the torque recording 60 of the Figure 2 Thus, an exemplary time-dependent torque curve 55 of the driver torque 62 is shown.

[0029] As in the Figure 2 To recognize, the current value of the driver torque 62 can change periodically over time 61, for example similar to a sinusoidal oscillation.

[0030] The sequence of procedure 10 according to a first embodiment of the invention is described in Figure 3 shown in a highly simplified schematic form.

[0031] In this procedure, the determined driver torque 62, in particular its instantaneous value determined by means of the torque sensor 107, is provided as a driver torque signal 50. In particular, the driver torque signal 50 thus exhibits the same fluctuating profile as the one in Figure 2 The torque curve shown over time is 55. This determination 1 of the driver torque signal 50 takes place in the first process step.

[0032] Subsequently, the driver torque signal 50 undergoes an initial filtering process (2) using a first low-pass filter. This first low-pass filter has a predetermined, constant time constant. This provides an initial smoothing of the driver torque signal 50.

[0033] After the first filtering stage 2, preferably immediately afterwards, a second filtering stage 3 is performed using a second low-pass filter. The second low-pass filter is designed as a separate filter from the first low-pass filter and, unlike the first low-pass filter, has a variable time constant.

[0034] Following the second filtering 3 using the second low-pass filter, the filtered driver torque signal 50 is multiplied by a support factor 5.

[0035] The support factor can, for example, be a predetermined constant numerical value. Alternatively, and preferably, the support factor can be variable and, for example, adjusted depending on the level of the determined driver torque 62. Alternatively, or additionally preferably, the support factor can be adjustable by manual input from the driver.

[0036] Depending on the driver torque signal 53 multiplied by the support factor, the drive unit 102 is then actuated by the control unit 103. This takes place in the step of controlled generation 4 of the motor torque.

[0037] The variable time constant of the second low-pass filter is adjusted depending on the difference in the driver torque signal 50 between an input and an output of the second low-pass filter. For this purpose, in an additional step 3a, the difference between the driver torque signal 50 at the input of the second low-pass filter and the driver torque signal 50 at the output of the second low-pass filter is determined.

[0038] In a simple embodiment, the adjustment of the second time constant can be carried out by increasing it during the execution of the method 10 if the difference decreases. This is the case, for example, if the driver torque curve 55 exhibits comparatively small fluctuations over time, as is the case, for example, in the Figure 2 shown in section B.

[0039] The increased second time constant results in stronger filtering or smoothing of the rider torque signal at such low measured differences. This means, for example, that short-term changes in rider torque are not immediately translated into a large change in motor torque, but rather that the drive unit 102 operates particularly smoothly. This is especially advantageous in driving situations where smooth propulsion of the e-bike 100 is desirable and no large changes in motor torque demand are necessary. In this case, the particularly effective filtering by means of the second low-pass filter with a high time constant provides a particularly high level of riding comfort, as, for example, unwanted fluctuations in motor torque can be avoided.

[0040] Similarly, the second time constant can be reduced if the difference increases. This can be the case, for example, if the driver torque curve exhibits large fluctuations over time, as is the case, for example, in the Figure 2 shown in section A.

[0041] The reduced second time constant in this case results in less filtering or smoothing of the driver torque signal 50 at such large differences. This allows the drive unit 102 to react faster and more directly to changes in the driver torque signal 50, giving the driver the impression that the drive is more responsive. This is particularly desirable in dynamically challenging driving situations to ensure a high level of driving comfort in these situations.

[0042] In an alternative or additional embodiment of method 10, the instantaneous value of the difference determined in step 3a is monitored. If the determined difference is greater than or equal to a predetermined threshold difference, the variable second time constant of the second low-pass filter is reduced to a value equal to or below a predetermined threshold time constant. Similarly, the variable second time constant of the second low-pass filter is preferably increased to a value greater than the predetermined threshold time constant if the determined difference is less than the predetermined threshold difference. This allows method 10 to be implemented particularly simply and cost-effectively.

[0043] Figure 4Figure 1 shows a highly simplified schematic view of a method 10 for operating a drive unit 102 of an electric bicycle 100 according to a second embodiment of the invention. The second embodiment essentially corresponds to the first embodiment of the invention. Figure 3 , with the difference being an alternative temporal sequence of the process steps. In detail, in the second embodiment, the multiplication 5 of the driver torque signal 50 by the support factor takes place between the first filtering 2 and the second filtering 3. Thus, the driver torque signal 50, already multiplied by the support factor, is filtered by the second low-pass filter during the second filtering 3. The driver torque signal 53' thus filtered and multiplied is then directly provided to the step of controlled generation 4 of the engine torque.

[0044] Preferably, the driver torque signal 50 and / or the difference can be continuously monitored in each of the described embodiments and the respective instantaneous value can be used to carry out the method 10.

[0045] Alternatively, it is particularly advantageous to record the driver torque signal 50 and / or the difference over a predetermined time period, whereby the variable second time constant of the second low-pass filter is adjusted depending on this recording. A particularly simple embodiment of the method 10 can be provided if the adjustment of the variable second time constant of the second low-pass filter is carried out depending on a determined maximum value of the recorded driver torque signal 50 and / or the difference within the predetermined time period.

Claims

1. Method for operating a drive unit (102) of an electric bicycle (100), comprising the following steps: - determination (1) of a rider torque signal (50) which is based on a rider torque (55) generated by means of muscle power of a person riding the electric bicycle (100), - first filtering (2) of the rider torque signal (50) by means of a first low-pass filter, - second filtering (3) of the rider torque signal (50) by means of a second low-pass filter, - controlled generation (4) of a motor torque by means of the drive unit (102) in dependence on the rider torque signal (53) filtered by means of the second low-pass filter, - wherein the second low-pass filter has a variable time constant which is adapted in dependence on the rider torque signal (50), characterized by the following step: - determination (3a) of a difference of the rider torque signal (50) between an input and an output of the second low-pass filter, wherein the variable time constant of the second low-pass filter is adapted in dependence on the difference, and / or - recording of the rider torque signal (50) over a predetermined time period and adaptation of the variable time constant in dependence on the recorded rider torque signal (50).

2. Method according to Claim 1, wherein the variable time constant of the second low-pass filter is increased when a decreasing difference is determined.

3. Method according to Claim 1 or 2, wherein the variable time constant of the second low-pass filter is decreased when an increasing difference is determined.

4. Method according to one of Claims 1 to 3, - wherein the variable time constant of the second low-pass filter is reduced to a value equal to or less than a predetermined threshold time constant when the determined difference is greater than or equal to a predetermined threshold difference, and / or - wherein the variable time constant of the second low-pass filter is increased to a value greater than the predetermined threshold time constant when the determined difference is less than the predetermined threshold difference.

5. Method according to Claim 1, also comprising the following step: determination of a maximum value of the recorded rider torque signal (50), wherein the adaptation of the variable time constant takes place in dependence on the maximum value.

6. Method according to one of the preceding claims, also comprising the following step: multiplication (5) of the rider torque signal (50) by a support factor, wherein the controlled generation of the motor torque takes place by means of the rider torque signal (53, 53') multiplied by the support factor.

7. Method according to Claim 6, wherein the multiplication (5) of the rider torque signal (50) takes place before or after the second filtering (2).

8. Method according to one of the preceding claims, wherein the first low-pass filter has a predetermined, constant time constant.

9. Method for operating a drive unit (102) of an electric bicycle (100), comprising the following steps: - determination (1) of a rider torque signal (50) which is based on a rider torque (55) generated by means of muscle power of a person riding the electric bicycle (100), - first filtering (2) of the rider torque signal (50) by means of a first low-pass filter, - second filtering (3) of the rider torque signal (50) by means of a second low-pass filter, and - controlled generation (4) of a motor torque by means of the drive unit (102) in dependence on the rider torque signal (53) filtered by means of the second low-pass filter, characterized by the following step: multiplication (5) of the rider torque signal (50) by a support factor, wherein the controlled generation of the motor torque takes place by means of the rider torque signal (53, 53') multiplied by the support factor.

10. Electric bicycle, comprising a drive unit (102) and a control unit (103) which is set up to actuate the drive unit (102) in a controlled manner, wherein the control unit (103) is further set up to carry out a method according to one of the preceding claims.