Drive system for an electric bicycle comprising a shift device, and method

Abstract

The invention relates to a drive system for an electric bicycle (1) comprising a shift device (14) and to a method. The drive system is provided for an electric bicycle (1), comprising a powertrain with at least one electric drive motor and at least one crank element, in each case for applying a drive force in order to drive a wheel of the electric bicycle (1), a shift device (14) for carrying out shifting processes in order to change the transmission ratio between the powertrain and the wheel (12) to be driven, and an electronic controller for controlling the shift device (14), wherein the controller is configured so as to determine whether a shifting process is to be carried out on the basis of a torque and / or a pedaling speed which is specified on the at least one crank element by an operator of the electric bicycle (1). The controller is configured so as to determine the process of carrying out the shifting process on the basis of at least one additional parameter. The invention also relates to a method.

Description

[0001] Drive system for an electric bicycle with a switching device and method

[0002] Description

[0003] The proposed solution relates to a drive system for an electric bicycle according to the preamble of claim 1 and a method according to claim 7.

[0004] It is known to provide an electric bicycle with a drive train comprising an electric drive motor and a crank element that engage a bottom bracket shaft to generate drive force for driving a wheel of the electric bicycle. To change the gear ratio between the drive train and the wheel to be driven, a gear shifting device is generally provided, allowing gear shifting to be performed. Gear shifting is typically initiated by the electric bicycle rider when desired. Alternatively, an electronic control device is provided that automatically initiates the gear shifting. The control device can trigger the gear shifting based on torque and / or pedaling speed of the rider.

[0005] Against this background, the proposed solution is based on the task of providing a drive system with a switching device and an electronic control device for controlling the switching device, which enables an improved driving experience.

[0006] According to a first aspect of the proposed solution, the problem is solved by a drive system for an electric bicycle according to claim 1. This system has a drive train with at least one electric drive motor and at least one crank element, each for applying a drive force for driving a wheel of the electric bicycle. The at least one electric drive motor can apply a motor drive force, and the at least one crank element can apply a rider drive force. The respective drive force can be applied to a bottom bracket shaft of the drive system in order to make it available for driving the wheel of the electric bicycle. The drive forces can be combined at the bottom bracket shaft to form a total drive force, which is transmitted to the wheel via a power transmission link such as a chain.

[0007] The drive system also includes a shifting device for performing shifting operations to change the gear ratio between the drive train and the driven wheel. With a high gear ratio, a relatively large wheel movement can be achieved with a high drive force. At the same pedaling speed, with a low gear ratio, only a small wheel movement can be achieved in the same time—but less drive force is required for this small movement.

[0008] The drive system also includes an electronic control device for controlling the shifting device, wherein the control device is configured to determine whether a shifting operation is to be performed based on a torque and / or pedaling speed specified by a rider of the electric bicycle on the at least one crank element. This allows the shifting operation to be automated, allowing the rider to better concentrate on riding.

[0009] The proposed solution is based on the idea of ​​improving the control device so that it controls the shifting device not only depending on rider input in the form of torque and / or cadence, in order to improve a positive and natural riding experience. Therefore, the control device is configured to determine the execution of the shifting operation based on at least one additional parameter. If at least one additional parameter can be used in addition to or as an alternative to the cadence and torque, the electronic control device can more precisely determine how the shifting device is to be controlled.

[0010] In one embodiment, the at least one further parameter is independent of the operating parameters of the drive system. The operating parameters can include parameters that must be specified anyway during the intended operation of the drive system on an electric bicycle in order to ensure proper operation and propulsion of the bicycle. These include, for example, the torque and pedaling speed. In this respect, the at least one parameter can, for example, be independent of the operating parameters of the drive system if it can be measured even if the drive system is not present during operation of the electric bicycle. In one embodiment, the drive system has an acceleration sensor with which the at least one further parameter can be provided in the form of an acceleration of the electric bicycle. The acceleration sensor can, for example, comprise an inertial measurement unit (IMU).

[0011] Acceleration is an example of a parameter that is independent of the drive system's operating parameters. It enables the electronic control unit to better assess the riding situation the electric bike is in and thus initiate gear changes more precisely. For example, when riding uphill and downhill, a change in acceleration can be used to more easily distinguish between ascents (uphill) and descents (downhill). Compared to basing the control of the gearshift unit solely on torque and / or pedaling speed, the alternative or additional use of acceleration allows for faster gear changes that are more tailored to the situation, which contributes to a positive and natural riding experience.

[0012] In one embodiment, the drive system has a GPS module with which the at least one further parameter can be provided in the form of a geolocation of the electric vehicle. The GPS (Global Positioning System) module can be used to further optimize the control of the switching unit compared to the use of acceleration. For example, during an uphill and downhill journey along a route, upcoming climbs and descents marked on a map can be anticipated using the geolocation, so that the control device can trigger a gear change even faster and more precisely, adapted to the driving situation. Here, the control device can be configured and provided to detect and analyze climbs and descents in advance.

[0013] In one embodiment, determining the execution of the switching operation includes determining a switching time. Using the switching time, the control device of the switching device can specify at what point in time the switching operation is to take place.

[0014] The proposed solution also relates to an electric bicycle with the drive system. According to a second aspect of the proposed solution, the problem is solved by a method for operating a drive system for an electric bicycle. The method comprises the following steps:

[0015] - Determining at least one parameter that is independent of an operating parameter of the drive system,

[0016] - Determining whether a gear shift is to be performed to change a gear ratio between a drive train of the electric bicycle and a wheel of the electric bicycle to be driven, based on a torque specified by a rider of the electric bicycle and / or a pedaling speed specified by the rider and based on the at least one parameter, and

[0017] - Carrying out the switching process.

[0018] The proposed solution also relates to a computer program product for an electronic control device for controlling a switching device for changing a gear ratio between a drive train and a wheel to be driven of an electric bicycle, in that the computer program product comprises instructions which, upon execution of the instructions, cause at least one processor of the control device to carry out the method.

[0019] The advantages and features described in connection with the first aspect of the proposed solution may also apply to the method according to the second aspect.

[0020] The attached figures illustrate possible embodiments of the proposed solution.

[0021] Here we show:

[0022] Figure 1 shows an electric bicycle with a variant of a proposed drive system; and

[0023] Figure 2 is a schematic view of a configuration of a

[0024] Control device.

[0025] Figure 1 shows an example of an electric bicycle 1 with a frame 10 on which a front wheel 11 and a rear wheel 12 are rotatably mounted. The rear wheel 12 can be driven with the assistance of an electric motor via a drive system with a drive train A. For this purpose, the drive train A has at least one electric drive motor in the form of an electric motor M. A drive torque generated by the electric motor M can be transmitted to the rear wheel 12 with the aid of a power transmission element 13, for example in the form of a chain or a belt, optionally in addition to a drive torque applied by muscle power via a bottom bracket shaft T. In this way, not only a first drive torque can be transmitted to the rear wheel 12, which is applied by a rider of the electric bicycle 1 via pedals connected to the bottom bracket shaft T.Rather, the rear wheel 12 can also be driven by a second drive torque generated by the electric motor M. The two drive torques can be provided as a total torque via the bottom bracket shaft T.

[0026] A shifting device 14 is provided between the drivetrain A and the driven rear wheel 12. Shifting operations can be performed with the shifting device 14 to change a gear ratio between the drivetrain A and the driven wheel 12. A shifting operation can be performed, for example, using a derailleur of the shifting device 14 on a hub of the rear wheel 12, which allows switching between different chainrings for the chain.

[0027] An electronic control device SE is provided to control the switching device 14. The control device SE is configured to determine whether a gear shift is to be performed. For this purpose, the control device SE can trigger the gear shift automatically via the switching device 14. To determine the timing of a gear shift as precisely as possible, the control device SE is coupled to an acceleration sensor 21 and a GPS module 20. The acceleration sensor 21 and the GPS module 20 can be arranged at any location on the electric bicycle 1. The positions shown are merely examples.

[0028] Figure 2 shows an exemplary configuration of the control device SE for controlling the shifting device 14. First, the control device SE is coupled to a frequency unit 22 and a torque unit 23. These provide a pedaling speed and a torque. The torque and pedaling speed are specified by a rider of the electric bicycle 1 on a crank element K. Based on the pedaling speed and / or the torque, the control device SE can determine whether a shifting operation should be performed. In addition, the control device SE can base its determination of whether a shifting operation should be performed on an acceleration of the electric bicycle 1 and a geolocation of the electric bicycle 1, which are provided to it via an acceleration sensor 21 and a GPS module 20. This can improve the determination, enabling an improved riding experience.

[0029] List of reference symbols

[0030] I Electric bike

[0031] 10 frames

[0032] II Front wheel

[0033] 12 rear wheel

[0034] 13 Power transmission link

[0035] 14 Switching device

[0036] 20 GPS module

[0037] 21 Accelerometer

[0038] 22 Frequency unit

[0039] 23 Torque unit

[0040] A drivetrain

[0041] K Crank element

[0042] M electric motor

[0043] SE Electronic control device

[0044] T bottom bracket spindle

Claims

Claims 1 . Drive system for an electric bicycle (1), with - a drive train (A) with at least one electric drive motor (E) and at least one crank element (K), each for applying a drive force for driving a wheel (12) of the electric bicycle (1), - a switching device (14) for carrying out switching operations to change a transmission ratio between the drive train (A) and the wheel (12) to be driven, and - an electronic control device (SE) for controlling the switching device (14), wherein the control device (SE) is configured to determine whether a switching operation is to be carried out based on a torque and / or a pedaling speed specified by a rider of the electric bicycle (1) on the at least one crank element (K), characterized in that the control device (SE) is configured to determine the execution of the switching operation based on at least one further parameter.

2. Drive system according to claim 1, characterized in that the at least one further parameter is independent of operating parameters of the drive system.

3. Drive system according to one of claims 1 or 2, characterized by an acceleration sensor (21) with which the at least one further parameter can be provided in the form of an acceleration of the electric bicycle (1).

4. Drive system according to one of claims 1 to 3, characterized by a GPS module (20) with which the at least one further parameter can be provided in the form of a geolocation of the electric bicycle (1).

5. Drive system according to one of the preceding claims, characterized in that the determination of the execution of the switching operation comprises a determination of a switching time.

6. Electric bicycle (1) with a drive system according to one of claims 1 to 5.

7. A method for operating a drive system for an electric bicycle (1), comprising the steps: - Determining at least one parameter that is independent of an operating parameter of the drive system, - Determining whether a gear shift is to be carried out to change a gear ratio between a drive train (A) of the electric bicycle (1) and a wheel of the electric bicycle (1) to be driven, based on a torque specified by a rider of the electric bicycle (1) and / or a pedaling speed specified by the rider and based on the at least one parameter, and - Carrying out the switching process.

8. Computer program product for an electronic control device (SE) for controlling a switching device (14) for changing a gear ratio between a drive train (A) and a wheel to be driven of an electric bicycle (1), wherein the computer program product comprises instructions which, upon execution of the instructions, cause at least one processor of the control device (SE) to carry out a method according to claim 7. *********

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