Method of effecting walking-while-pushing assist of electric bicycle

Abstract

To provide a rider of an electric bicycle with especially high user-friendliness in a walking-while-pushing situation.SOLUTION: The present invention relates to a method of effecting walking-while-pushing assist of an electric bicycle (100). The electric bicycle (100) includes a drive unit (2) that generates a propulsive force, and a gearshift stage changer (3) interposed between the drive unit (2) of the electric bicycle (100) and a drive wheel (101). The gearshift stage changer (3) is electronically operable. A method includes steps to be executed in a walking-while-pushing assist mode of the electric bicycle (100), that is, a step of calculating an instantaneous gear ratio of the gearshift stage changer (3), a step of activating the drive unit (2) for the purpose of generating a walking-while-pushing assist motor torque, and a step of controlling the gear ratio of the gearshift stage changer (3) according to the calculated instantaneous gear ratio and thus making the gear ratio adaptable.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for operating a push-walking assist for an electric bicycle and to an electric bicycle. [Background technology]

[0002] Electric bicycles with a push-assist function are known. In this case, for example in response to a button pressed by the rider of the electric bicycle, a motor torque is generated by the drive unit of the electric bicycle, which can assist the rider in pushing the bicycle. If the drive concept is a central motor, i.e. if the drive unit is arranged in the bottom bracket of the electric bicycle, the transmission of the generated push-assist motor torque takes place via a further drive train to the rear wheel of the electric bicycle. The drive torque acting on the rear wheel of the push-assist thus depends on the instantaneous gear ratio of the drive train, for example the shifting device. Depending on the current gear ratio, the resulting thrust of the push-assist may be too weak or too strong for the instantaneous situation. Furthermore, it is often necessary to limit the maximum speed of the electric bicycle generated by the push-assist, typically to a maximum of 6 km / h. In this case, the control is often performed by a speed signal measured at the rear wheel. Especially at such low speeds, the speed detection is often inaccurate. Summary of the Invention

[0003] In contrast, the method according to the invention having the features of claim 1 is distinctive in that it provides an optimized pushing assistance for an electric bicycle, which can provide an especially high level of user comfort for the rider of the electric bicycle in a large number of possible pushing situations. In particular, it is then possible to always provide an optimal pushing assistance in an especially simple and comfortable manner. This is achieved according to the invention by a method for operating a pushing assistance for an electric bicycle, which comprises a drive unit for generating a propulsive force and a gear shift device between the drive unit and the drive wheels of the electric bicycle. In this case, the gear shift device is designed to be electronically operable. In this case, the method comprises the following steps, which are performed in a pushing assistance mode of the electric bicycle, namely: - calculating an instantaneous gear ratio of a gear shift device; - operating the drive unit to generate a pushing-walking assist motor torque; - controlling and adapting the gear ratio of the gear shifting device depending on the calculated instantaneous gear ratio.

[0004] In that case, any gear-shift device that can provide a number of different discrete gear ratios, for example an external gearbox with a number of gears, can be provided as the gear-shift device. Alternatively, a gear-shift device with a continuously variable gear ratio, for example a CVT gearbox, can also be preferably provided.

[0005] The instantaneous gear ratio can be calculated, for example, by an electronic operating device of the gear shift device, and the instantaneous gear ratio can be, for example, an electronic signal of the operating device.

[0006] In other words, in this method, in particular in response to the start of the push-assist mode, in particular in response to a generated push-assist signal, which can be generated by a user input, first an instantaneous gear ratio of the gear shifter is calculated. In addition, in the push-assist mode, an operation of the drive unit is performed to generate a push-assist motor torque that provides a propulsive force for the electric bicycle. In addition, a controlled adaptation of the gear ratio of the gear shifter is performed in response to the calculated instantaneous gear ratio, in particular via an electronic operating device.

[0007] In particular, the controlled adaptation of the gear ratio can take place during operation of the drive unit, or, alternatively and preferably, the gear ratio can be adapted first, in particular immediately followed by the start of operation of the drive unit.

[0008] The controlled adaptation of the gear ratio can in particular be regarded as a shifting process or "shifting".

[0009] Thus, this method provides the advantage that the current gear ratio between the drive unit and the drive wheel of the electric bicycle is taken into account and adapted appropriately during the operation of the electric bicycle push-assist. In this case, the gear ratio can be adapted based on various factors, for example on sensor data representing the current pushing situation of the electric bicycle. Alternatively or additionally, a particularly simple method can be provided in which a predefined gear ratio suitable for a number of pushing situations is always provided. Thus, for example, if the gear ratio of the gear shifting device is particularly small or large before or at the start of the pushing-assist mode, the gear ratio suitable for pushing the electric bicycle can be adjusted to one suitable for pushing the electric bicycle at the start of the pushing-assist mode. This makes it possible to provide the electric bicycle user with a particularly high level of comfort when pushing the electric bicycle.

[0010] The dependent claims are preferred developments of the invention.

[0011] Preferably, the drive unit is operated to provide a constant walking assist motor torque during the walking assist mode, i.e. the walking assist motor torque of the drive unit, which is directly present on the output shaft of the drive unit, is not changed but is always generated at a constant value in the walking assist mode, thereby providing a particularly simple and efficient walking assist operation.

[0012] Particularly preferably, the gear ratio of the gear shifting device is adapted in a controlled manner to provide a predefined assist gear ratio in the assist mode, i.e. exactly one preferred gear ratio, the assist gear ratio, is defined and this gear ratio is automatically adjusted in the assist mode, thereby making the method particularly simple and inexpensive to implement.

[0013] In particular, at least two different desired gear ratios are defined. In this case, the gear ratio difference between each of the desired gear ratios and the calculated instantaneous gear ratio is calculated in the method. A controlled adaptation of the gear ratio of the gear shifter is then performed to adjust the gear ratio from the instantaneous gear ratio to the closest desired gear ratio. That is, for example, in a gear shifter with multiple gears, at least two preferred gears are defined. In this case, in the pushing assistance mode, the gear is shifted to the closest gear from the calculated instantaneous gear or gear ratio. This makes it possible, for example, to make it possible to make a minimal change in the gear ratio, so that a gear ratio well suited to the pushing operation can be entered particularly quickly.

[0014] More preferably, in the push-assist mode, the instantaneous speed of the electric bicycle is additionally calculated. In that case, the controlled adaptation of the gear ratio of the gear shifting device is additionally performed depending on the calculated instantaneous speed of the electric bicycle. For example, in that case, the speed of the electric bicycle generated by the propulsive force of the push-assist motor torque, especially in the case of a constant push-assist motor torque and / or in the case of a constant motor speed, can be controlled by adapting the gear ratio. For example, in that case, the controlled adaptation of the gear ratio can be controlled so that a predetermined maximum pushing speed is not exceeded. This allows the adaptation of the push-assist to be optimally adjusted to the instantaneous movement of the electric bicycle, which allows for an especially high level of user comfort for the rider.

[0015] Preferably, the instantaneous speed of the electric bicycle is calculated based on the calculated instantaneous gear ratio and the instantaneous motor speed of the drive unit. That is, the instantaneous speed is calculated based on information of the total gear ratio between the output shaft of the drive unit of the electric bicycle and the drive wheel, which is dependent on the instantaneous gear ratio of the gear shifting device, and the instantaneous motor speed. In particular, the motor speed can be calculated by a sensor and / or based on the control of the drive unit. This allows the instantaneous speed to be calculated particularly accurately and with high temporal resolution.

[0016] In particular, the controlled adaptation of the gear ratio of the gear shifter is performed in such a way that the instantaneous speed of the electric bicycle is kept below a predetermined maximum walking speed, in particular for a constant predetermined motor torque and / or a constant predetermined motor speed. For example, the maximum walking speed can be 6 km / h. This makes it possible to simply and reliably ensure that, for example, the walking assistance does not move the electric bicycle faster than a defined maximum speed.

[0017] Particularly preferably, the controlled adaptation of the gear ratio of the gear shifter is additionally performed on the basis of a calculated motor torque of the drive unit. In particular, the motor torque can be calculated by a torque sensor and / or preferably on the basis of the drive of the drive unit. Preferably, in that case, the controlled adaptation of the gear ratio is performed in such a way that the gear ratio is reduced if the calculated instantaneous motor torque is equal to or greater than a predetermined target motor torque, particularly preferably if the additionally calculated speed is equal to or less than a predetermined target pushing speed and / or if the calculated speed decreases. In other words, if the instantaneous gear ratio is too large to allow the movement of the electric bicycle to be efficiently performed by the drive unit, the gear ratio is reduced. For example, this may be the case in the case of large gradients. Alternatively or additionally, preferably, the gear ratio can be increased on the contrary if the calculated instantaneous motor torque is less than the predetermined target motor torque and / or in particular if the calculated speed increases.

[0018] More preferably, in the assist mode, the instantaneous gradient on which the electric bicycle is located is calculated, in which case the gear ratio of the gear shifter is adapted in a controlled manner, additionally as a function of the calculated instantaneous gradient, particularly preferably additionally based on the weight of the electric bicycle, thereby providing a particularly efficient and comfortable assist function.

[0019] In particular, in the assisted-push mode, the instantaneous motor speed is additionally calculated, in particular by means of a sensor and / or based on the drive of the drive unit. A controlled adaptation of the gear ratio of the gear shift device is then performed in order to keep the motor speed below a predetermined maximum speed, in particular the maximum speed being observed in the case of a predetermined target pushing speed, which is set in particular in the assisted-push mode. In particular, this allows the noise emission of the drive unit to be kept low, which in turn provides a particularly high level of user comfort.

[0020] Preferably, in the push-assist mode, a calculation of the drive wheel torque is additionally performed based on the calculated motor torque of the drive unit and the calculated instantaneous gear ratio. In this case, a controlled adaptation of the gear ratio of the gear shifter is performed so that the drive wheel torque is kept within a predetermined torque range. In particular, the torque range can include a range from a predetermined target drive wheel torque and a deviation of up to 5%, preferably up to 10%. This allows a constant push-assist to be provided even in changing pushing situations, such as changes in gradient, thereby enabling a particularly high user comfort for the electric bicycle rider.

[0021] Furthermore, the present invention relates to an electric bicycle comprising a drive unit, an electronically operable gear shifter and a control unit, the control unit being in particular configured to controllably operate the drive unit and the gear shifter, and the control unit being configured to execute the above-mentioned method for operating a push-assist for an electric bicycle. [Brief description of the drawings]

[0022] [Figure 1] 1 is a simplified schematic diagram of an electric bicycle on which a method according to a first exemplary embodiment of the present invention is performed; [Diagram 2] FIG. 2 is a simplified schematic diagram of the signal flow when performing the method of the first exemplary embodiment; [Diagram 3] FIG. 2 is a simplified schematic diagram of the steps of the method of the first exemplary embodiment. [Figure 4] FIG. 4 is a simplified schematic diagram of the steps of a method according to a second exemplary embodiment of the present invention. [Diagram 5] FIG. 11 is a simplified schematic diagram of the steps of a method according to a third exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The invention is explained below on the basis of exemplary embodiments with reference to the figures, in which functionally identical components are respectively provided with the same reference numerals.

[0024] 1 shows a simplified schematic diagram of an electric bicycle 100 having a drive unit 2 and a gear shift device 3. The drive unit 2 is arranged in the area of ​​the bottom bracket of the electric bicycle 100 and comprises a motor, in particular an electric motor. The motor can be supplied with electrical energy by an electrical energy store 105 of the electric bicycle 100.

[0025] The motor torque generated by the drive unit 2 can be used to assist the pedaling force generated by the muscles of the rider of the electric bicycle 100.

[0026] In Fig. 1, the gear shifting device 3 of the electric bicycle 100 is shown in a highly simplified schematic manner. In particular, the gear shifting device 3 comprises at least one shifting device by means of which the gear ratio in the drive train of the electric bicycle 100 can be changed, in particular between the drive unit 2 and the drive wheel 101, which is the rear wheel of the electric bicycle 100. For example, the shifting device can be provided on the rear wheel hub and / or on the chain ring as an external derailleur, in particular by means of sprockets of different sizes, providing different gear ratios. Alternatively, and preferably, other types of shifting devices, for example gear trains or internal derailles, or the shifting device can provide a continuously variable gear ratio.

[0027] In that case, the gear shifter 3 is configured to be electronically operable, i.e. a change in the gear ratio of the gear shifter 3 can be triggered by an electronic shifting signal. Preferably, the gear shifter 3 then comprises an actuator that is arranged to change the gear ratio in response to receiving the shifting signal, for example by moving a shifting mechanism. The shifting signal can in particular be generated by manual operation by the rider of the electric bicycle 100.

[0028] In addition, the electric bicycle 100 comprises a control unit 5 which is arranged to operate the drive unit 2 and the gear shifting device 3. In particular, the control unit 5 can be integrated in the drive unit 2 as shown in a simplified schematic form in Fig. 1. The control unit 5 is formed so as to be able to generate shifting signals. In addition, the control unit 5 is then arranged to execute the method for operating the walking assistance of the electric bicycle 100 according to the first exemplary embodiment of the present invention.

[0029] The method will now be explained in more detail, with reference to Figures 2 and 3. Figure 2 shows a simplified schematic diagram of the signal flow, in particular between the drive unit 5 and the gear shift device 3, when carrying out the method.

[0030] In this method, in the pushing-walking assist mode, the control unit 5 operates the drive unit 2 so that the drive unit 2 generates a constant pushing-walking assist motor torque. As a result, the drive wheel 101 of the electric bicycle 100 is driven via the drive train of the electric bicycle 100, particularly including the gear shift device 3, so that the drive wheel has a drive wheel torque that provides propulsion for the electric bicycle 100. As a result, the motor torque of the drive unit 2 can be used to assist the rider when pushing the electric bicycle 100.

[0031] In this way, the method provides for an accurate adaptation of the gear ratio of the electronic gear shifter 3 in the push-assist mode. For this purpose, the control unit 5 generates a shift signal 35, which is transmitted to the electronic gear shifter 3 in such a way that it causes a change in the gear ratio.

[0032] In that case, the shift signal 35 is generated as a function of the calculated instantaneous gear ratio of the gear change device 3. This instantaneous gear ratio can be calculated by the control unit 5, in particular on the basis of the gear signal 31 which represents the currently engaged gear of the gear change device 3.

[0033] Additionally, further signals, in particular a motor speed signal 61 generated by a motor speed sensor 6, and in particular a speed signal 71 representing the instantaneous speed of the electric bicycle 100, can be used, based on which a controlled adaptation of the gear ratio of the gear shift device 3 is carried out.

[0034] In that case, the speed signal 71 can be provided, for example, by the speed sensor 7. Alternatively, the speed signal 71 can be provided on the basis of a calculation in the control unit 5, in particular on the basis of the calculated instantaneous gear ratio of the gear shift device 3 and on the basis of the motor speed, so that a particularly accurate calculation of the speed of the electric bicycle 100 can be made.

[0035] In that case, in a first exemplary embodiment of the method, a particularly simple implementation is carried out. The procedure of the method is shown in a simplified schematic form in the flow chart 50 in FIG. 3, which is formed in particular as a decision diagram. In that case, in a first step 51, it is determined whether the push-assist mode is active. If this is not the case, a negative route 62 is taken and no further steps are carried out. If the push-assist mode is active, a positive route 61 is followed to the next step 52, in which it is determined whether the calculated instantaneous gear ratio of the gear shifter 3 corresponds to a predefined push-assist gear ratio. If this is not the case, a negative route 62 is taken and a next step 53 is carried out, in which the gear shifter 3 is operated to change to the predefined push-assist gear ratio. If the predefined push-assist gear ratio is already present, a positive route 61 is taken and no further steps are carried out.

[0036] Therefore, in the pushing assist mode, while the pushing assist motor torque is generated by the drive unit 2, it is always possible to ensure that the gear shift device 3 provides a predetermined pushing assist gear ratio to provide suitable pushing assistance to the rider of the electric bicycle 100 in a variety of pushing situations.

[0037] FIG. 4 shows a simplified schematic diagram of a flow chart 50 of a method according to a second exemplary embodiment of the invention. The second exemplary embodiment corresponds substantially to the first exemplary embodiment of FIGS. 1 to 3, but differs in that two different target gear ratios are defined to which the gear shift device 3 can be switched during the push-walking assist mode. In that case, in a second step 52 of the method, a determination is made whether one of the two predefined target gear ratios is present at the moment. If this is not the case, then, following route 62, in a next step 53, the gear ratio difference between each of the target gear ratios and the calculated instantaneous gear ratio is calculated. In addition, the gear ratio of the gear shift device 3 is controlled and adapted to adjust to the closest target gear ratio.

[0038] This makes it possible to provide a gear ratio that is favorable for the push-walking assistance by requiring fewer gear changes in the push-walking assistance mode, which further increases user comfort.

[0039] Figure 5 shows a simplified schematic diagram of a flow chart 50 of a method according to a second exemplary embodiment of the present invention. The second exemplary embodiment substantially corresponds to the first exemplary embodiment of figures 1 to 3, but differs in that it provides a more flexible adaptation of the gear ratio depending on the motor torque and speed.

[0040] In a second step 56 it is then determined whether the instantaneous motor torque of the drive unit 2 is greater than or equal to a predetermined target motor torque. In particular, the target motor torque can be 90% of the maximum motor torque that can be provided. If this is the case according to route 61, then in the next step 57 it is determined whether the calculated instantaneous speed is to be reduced. If this is the case, then via route 61, the next step 58 is carried out, in which the gear ratio of the gear shift device 3 is reduced. In particular, the next smaller gear is then shifted to.

[0041] This allows a particularly precise and efficient adaptation of the pushing assistance to the instantaneous pushing situation, ensuring that optimal assistance is always provided to the rider of the electric bicycle 100 when pushing. [Explanation of symbols]

[0042] 100 Electric Bike 101 Drive wheel 105 Energy Reservoir 2 Drive unit 3 Gear shift device 31 Gear signal 35 Switching signal 50 Flowchart 51 Steps 52 Steps 53 Steps 56 Steps 58 Steps 5. Control Unit 6 Motor speed sensor 61 Motor speed signal, positive route 62 No Route 71 Speed ​​signal

Claims

1. A method for operating a pushing assist function of an electric bicycle (100), the electric bicycle (100) comprising a drive unit (2) for generating a propulsive force, and a gear shifting device (3) between the drive unit (2) and a drive wheel (101) of the electric bicycle (100), the gear shifting device (3) being configured to be electronically operable, the method comprising steps executed in a pushing assist mode of the electric bicycle (100), comprising: - calculating an instantaneous gear ratio of the gear shift device (3); - operating the drive unit (2) to generate a pushing assist motor torque; - controlling and adapting the gear ratio of the gear-shift device (3) depending on the calculated instantaneous gear ratio.

2. 2. The method of claim 1, wherein the operation of the drive unit (2) is performed to provide a constant assisted-push motor torque during the assisted-push mode.

3. 3. The method according to claim 1 or 2, wherein the gear ratio of the gear shift device (3) is adapted in a controlled manner to provide a predetermined pushing assist gear ratio.

4. at least two different target gear ratios are defined, - a gear ratio difference between each of said target gear ratios and said calculated instantaneous gear ratio is calculated, The method according to claim 1 or 2, wherein the gear ratio of the gear shift device (3) is adapted in a controlled manner to adjust to the closest target gear ratio.

5. In the pushing-walking assist mode, an instantaneous speed of the electric bicycle (100) is additionally calculated; The method according to any one of claims 1 to 4, wherein the controlled adaptation of the gear ratio of the gear shift device (3) is additionally effected as a function of the calculated instantaneous speed.

6. 6. The method according to claim 5, wherein the instantaneous speed is calculated based on the calculated instantaneous gear ratio and an instantaneous motor speed of the drive unit (2).

7. 7. The method according to claim 5 or 6, wherein the controlled adaptation of the gear ratio of the gear shifting device (3) is performed such that the instantaneous speed of the electric bicycle (100) is kept below a predetermined maximum pushing speed.

8. 8. The method according to claim 1, wherein the controlled adaptation of the gear ratio of the gear shift device (3) is additionally performed on the basis of a calculated motor torque of the drive unit (2), in particular in such a way that the gear ratio is reduced if the calculated instantaneous motor torque is equal to or greater than a predetermined target motor torque, in particular additionally if the calculated speed is equal to or less than a predetermined target pushing speed and / or if the calculated speed decreases.

9. In the pushing walking assist mode, an instantaneous gradient is additionally calculated, The method according to any one of claims 1 to 8, wherein the controlled adaptation of the gear ratio of the gear shift device (3) is additionally performed as a function of the calculated instantaneous gradient, in particular additionally based on the weight of the electric bicycle (100).

10. 10. The method according to claim 1, wherein in the pushing-assist mode, a calculation of the instantaneous motor speed is additionally performed, and the controlled adaptation of the gear ratio of the gear shift device (3) is performed in order to keep the motor speed below a predetermined maximum speed, in particular at a predetermined target pushing speed.

11. In the pushing-walking assist mode, a drive wheel torque is additionally calculated based on the calculated motor torque of the drive unit (2) and the calculated instantaneous gear ratio; The method according to any one of the preceding claims, wherein the controlled adaptation of the gear ratio of the gear shift device (3) is performed in such a way that the drive wheel torque is kept within a predetermined torque range.

12. An electric bicycle, a drive unit (2), a gear shift device (3) configured to be electronically operable; - a control unit (5) configured to carry out the method according to any one of claims 1 to 11.

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