Drive unit for a bicycle and bicycle with a drive unit

Abstract

A drive unit (1) for a bicycle (2) that can be propelled at least temporarily by muscle power is provided with an electric machine (3) for providing a motive force, a crank assembly (4) for applying muscle power, an output element (5) for transmitting a combined motive force to a drive wheel (6) of the bicycle (2), and a transmission unit (7) for transmitting the combined motive force to the drive wheel (6). A switchable freewheel (9) is provided between the electric machine (3) and the output element (5), while no freewheel is provided in the transmission unit (7) between the drive wheel (6) and the drive unit (1).

Description

[0001] This document describes a drive system for a bicycle, enabling the bicycle to be propelled. It also describes a bicycle equipped with such a drive system. Specifically, this description relates to a drive system for a bicycle powered at least intermittently by muscle power, where an electric motor can provide supplementary power for propelling the bicycle.

[0002] Drive systems for bicycles, especially for pedelecs or e-bikes, are known. These systems combine the muscle power of a bicycle, applied via a crank mechanism, with a driving force provided by an electric motor. The combined driving force is used to propel the bicycle. In known drive systems, electrical energy is consumed when the electric motor is operating, while when coasting or going downhill, the bicycle rolls or is braked by a braking device. A bicycle according to the prior art is disclosed, for example, in EP 4 273 033 A1.

[0003] The objective is to provide an improved drive system for a bicycle that enhances the efficiency of using an electric motor. This objective is achieved with a drive system having the features of claim 1 and with a bicycle having the features of claim 6. Advantageous embodiments are defined in the dependent claims.

[0004] A drive system for a bicycle that can be propelled at least temporarily by muscle power comprises an electric motor for providing a driving force, a crank mechanism for applying muscle power, an output element for delivering a combined driving force, and a transmission device for transferring the combined driving force to the drive wheel. A first freewheel is provided between the crank mechanism and the output element to allow the driving force to be transferred from the crank mechanism to propel the bicycle.A second freewheel is provided between the electric machine and the output element, wherein the second freewheel can be switched in such a way that in a first state of the second freewheel a torque from the electric machine to the output element can only be transmitted in one direction of rotation for the propulsion of the bicycle, and in a second state of the second freewheel a torque between the electric machine and the output element can be transmitted in both directions of rotation or alternatively only in the direction of rotation opposite to the direction of rotation for propulsion.

[0005] A bicycle that can be propelled, at least temporarily, by muscle power can be designed as an e-bike or pedelec. The drive unit can be attached to the bicycle frame. The transmission device for transferring the combined drive power to the drive wheel can include a traction drive. The transmission device can also include a mechanism for adjusting the gear ratio between the output element and the drive wheel. The drive wheel can be a rear wheel of the bicycle. The bicycle can have one or more drive wheels. In particular, the bicycle can have two wheels or more than two wheels.

[0006] According to one embodiment, a torque can be introduced into the electric machine from the output element when the second freewheel is in the second state. In this case, power transmission between the drive wheel and the electric machine can occur via the transmission device such that rotation of the drive wheel results in rotation of the electric machine.

[0007] According to one embodiment, the drive device can be operated in a recuperative mode when the second freewheel is in the second state, so that a torque applied to the output element is applied to the electric machine.

[0008] According to one embodiment, the electric machine can be operated as a generator in recuperative mode and can generate usable electrical energy when torque is applied from the output element. This electrical energy can be stored, in particular, in an electrical energy storage device, such as an electrical storage battery. In recuperative mode, mechanical power available at the drive wheel can be converted into electrical power by driving the electric machine.

[0009] According to one embodiment, the second freewheel can be moved into the second state by a command when a recuperation request is received. In particular, the command can be entered by the vehicle's rider via an input device provided on the bicycle. In this case, the bicycle rider can specify whether or not recuperation should occur. Furthermore, the command can be generated by a control unit that, based on the bicycle's operating states, can at least partially and automatically initiate operation with recuperation. Alternatively, the command can be generated by actuating a brake on the bicycle, so that recuperation can occur when the brake is applied. Recuperation requires a drive force at the rear wheel that can power the electric motor.Therefore, inertia and deceleration of the bicycle can generate a driving force. Furthermore, driving force can be generated when cycling downhill.

[0010] According to one aspect, a bicycle has a drive unit with one or more of the aforementioned features, wherein the bicycle has a drive wheel and a transmission unit for transmitting torque between the drive unit and the drive wheel.

[0011] According to one embodiment, the transmission device for transmitting torque between an output element of the drive unit and the drive wheel can be configured in both a propulsion mode and a rebound mode. This configuration makes it possible to apply a driving force provided by the electric machine to the drive wheel for propulsion. Furthermore, in a predetermined operating state, it allows a torque delivered by the drive wheel to be transmitted to the electric machine in rebound mode, enabling the electric machine to operate as a generator for producing electrical power.

[0012] According to one embodiment, a torque transmission path between the output element of the drive unit and the drive wheel can be designed without a freewheel. This design allows both the propulsion mode and the rebound mode for the bicycle to function without interfering with the torque transmission path between the output element of the drive unit and the drive wheel. According to an alternative embodiment, a torque transmission path between the output element of the drive unit and the drive wheel can be equipped with a switchable freewheel, in which the freewheel function can be selectively deactivated.

[0013] According to one embodiment, a hub gear can be provided on the drive wheel, via which the drive wheel is coupled to the drive unit. A hub gear can be designed without a freewheel, so that a torque transmission path between the drive wheel and an input element of the hub gear can transmit torque to the output element in both propulsion and deceleration modes. Furthermore, the hub gear can allow the gear ratio between the drive wheel and the output element to be adjusted in both propulsion and deceleration modes. The hub gear can provide two or more gear ratios. The hub gear can be manually shifted by the bicycle rider to adjust the gear ratio. Alternatively, the hub gear can be shifted via an output signal from the control unit.In this case, a suitable gear ratio can be set at least partially automatically in propulsion mode. Additionally, a gear ratio suitable for recuperation operation can also be set at least partially automatically in deceleration mode.

[0014] According to one embodiment, a control device may also be provided, which is configured to selectively control the state of the second freewheel based on an evaluation of the bicycle's operating state or on the basis of inputs from the rider, in order to enable or prevent recuperative operation of the electric machine. In this embodiment, information regarding the bicycle's operating state may be supplied to the control device. This information may include the charge level of the electrical energy storage device, a torque delivered by the drive wheel or a related value, the bicycle's speed, the actuation state of the bicycle's braking system, the gradient on which the bicycle is located, or other relevant information.

[0015] The control unit can be integrated into the drive unit. Alternatively, the control unit can be a separate unit mounted on the bicycle. Based on the setting of the first state or the second state of the second freewheel, the control unit can determine whether or not recuperation should occur. Additionally, the control unit can adjust the degree of recuperation, in particular the braking torque generated by the electric motor in recuperative mode, based on information about the bicycle's operating state.

[0016] The first freewheel between the crank mechanism and the output element allows the crank mechanism to apply driving force to the drive wheel, propelling the bicycle. Furthermore, this measure prevents the crank mechanism from being driven by the drive unit, particularly the electric motor or the drive wheel. This design allows the drive unit to both recuperate electrical energy and maintain the operation of a conventional bicycle. Fig. Figure 1 shows a schematic representation of a bicycle with a drive unit in one embodiment; and Fig. Figure 2 shows a simplified representation of the structure of a drive unit in one embodiment.

[0017] Fig. Figure 1 shows a bicycle 2, which in a known manner has a frame, a steering mechanism, a saddle, and two wheels. In particular, the bicycle 2 has a drive wheel 6, which is designed as the rear wheel of the bicycle 2. Furthermore, the bicycle 2 has a drive unit 1, which in the present embodiment is mounted on the frame of the bicycle 2. The drive unit 1 is in Fig. Figure 1 is shown only as an example and includes an electric machine 3 integrated into the drive unit 1. Furthermore, the drive unit 1 includes a crank mechanism 4 with which a rider of the bicycle 2 can apply muscle power to the drive unit 1. The drive unit 1 also includes an output element 5, which is coupled to the drive wheel 6 via a transmission device 7. In the present embodiment, the output element 5 is designed as a sprocket. The sprocket is coupled to the drive wheel 6 via a link chain and a pinion. The transmission device 7 enables power transmission between the drive wheel 6 and the output element 5 of the drive unit 1.

[0018] The Fig. The bicycle 2 shown in Figure 1 further comprises elements not shown, such as an electrical energy storage device coupled to the drive unit 1 for energy exchange, as well as a braking device and other elements suitable for a bicycle. Additionally, the drive unit 1 comprises a control unit 10, which in the present embodiment is integrated into the drive unit 1. The control unit 10 has interfaces for receiving and outputting signals used to control the drive unit 1.

[0019] Fig. Figure 2 shows a schematic representation of the structure of the drive unit 1. As in Fig. As shown in Figure 2, the drive unit comprises the crank assembly 4, which has a rotatably mounted shaft that is guided through the drive unit 1 in the transverse direction of the bicycle 2. The drive unit 1 also comprises the aforementioned electric machine 3, which is coupled to an electrical energy storage device (not shown) for the exchange of electrical energy.

[0020] With regard to torque transmission, a torque transmission path is provided between the electric machine 3 and the output element 5 of the drive unit 1. In this torque transmission path between the electric machine 3 and the output element 5, a gear arrangement 11 (not described in detail) is provided in the present embodiment to adapt the output speed of the electric machine 3 to the required speed of the output element 5. Furthermore, the crank assembly 4 is coupled to the output element 5 by a gear arrangement 12 (not described in detail) such that a drive force applied to the crank assembly 4 can be applied to the output element 5 for propulsion.

[0021] This design enables torque to be applied to the output element 5 for propulsion of the bicycle 2 from both the electric machine 3 and the crank mechanism 4. The output element 5 is coupled to the drive wheel 6 via the aforementioned transmission device 7.

[0022] The specific design of the drive unit 1 is explained below. A first freewheel 8 is provided in the power transmission path between the crank assembly 4 and the output element 5. In the present embodiment, the first freewheel 8 is mounted on a shaft of the crank assembly 4 and coupled to the output element 5 via the aforementioned gear arrangement 12. The first freewheel 8 is designed as a non-switchable freewheel. The first freewheel 8 enables torque transmission from the crank assembly 4 to the output element 5 in a direction of rotation that propels the bicycle 2 forward. Due to the design of the first freewheel 8, no force can be transmitted to the output element 5 in the opposite direction of rotation of the crank assembly 4.

[0023] Furthermore, a second freewheel 9 is provided in the torque transmission path between the electric machine 3 and the output element 5. In the present embodiment, the second freewheel 9 is located on an output shaft of the electric machine 3. The second freewheel 9 is designed as a switchable freewheel that can be moved into a first state and a second state. In the present embodiment, the second freewheel 9 is moved into the first state or the second state by a signal output by the control device 10. For this purpose, an electrical switching element can be provided in the second freewheel 9, which determines the first state or the second state by controlling an electrical current. In an alternative embodiment, a mechanical switching element is provided with which the second freewheel 9 can be moved into the first state or the second state.In the first state of the second freewheel, torque transmission from the electric machine 3 to the output element 5 is enabled, while the second freewheel 9, in the opposite direction of rotation, does not allow any power transmission between the electric machine 3 and the output element 5. In the second state of the second freewheel 9, the freewheel function of the second freewheel is deactivated. Therefore, depending on the design of the second freewheel 9, torque can be transmitted between the electric machine 3 and the output element 5 in the second state of the second freewheel 9 in the opposite direction of rotation or in both directions of rotation.

[0024] In the present embodiment, the output element 5 is designed as a sprocket. The transmission device 7, in this embodiment, comprises a link chain that encircles the output element 5 in the form of the sprocket. Furthermore, the transmission device 7 has a pinion that is mounted concentrically on the drive wheel 6. In this embodiment, the transmission device 7 has a hub gear mounted on the drive wheel 6. Thus, the present design enables power transmission between the output element 5 and the drive wheel 6 via the transmission device 7. In this embodiment, the transmission device 7 is designed such that power transmission between the output element 5 and the drive wheel 6 can occur in both directions of rotation.For this reason, the transmission device 7 in the present embodiment uses a hub gear, as its design enables such torque transmission in two directions of rotation. In the present design, no freewheel is provided within the torque path between the output element 5 and the drive wheel 6. Specifically, the hub gear uses a design in which a freewheel is not provided between the pinion and the hub gear elements.

[0025] The following section explains the operation of the drive unit 1 in more detail. In operation using muscle power, the rider of the bicycle 2 applies muscle power to the crank assembly 4, which in turn powers the drive unit 1. The driving force is transmitted via the first freewheel 8 to the output element 5 and then, via the transmission unit 7, to the drive wheel 6, thus propelling the bicycle 2. If assistance is required from the electric motor 3, the electric motor 3 is powered by the supply of electrical energy to propel the bicycle 2. The torque delivered by the electric motor 3 is transmitted via the second freewheel 9 to the output element 5, to which the torque from the crank assembly 4 is simultaneously transmitted, provided the rider of the bicycle 2 applies torque to the crank assembly 4.In this state, a combined driving force is transmitted to the output element 5 and further to the drive wheel via the transmission device 7. If the rider of the bicycle 2 stops operating the crank mechanism 4, the output element 5 continues to be driven by the rotation of the drive wheel 6 due to the design of the transmission device 7. However, the first freewheel 8 prevents the rotation of the output element 5 from being transmitted to the crank mechanism 4 in this state.

[0026] If recuperation is not requested, the second freewheel 9 is moved to the first state, in which no torque can be transmitted from the output element 5 to the electric motor 3 when the bicycle 2 is moving forward. In this state, the bicycle 2 is in a rolling state, in which the electric motor 3 is stationary and, if applicable, the crank mechanism 4 is not operated.

[0027] In the event that recuperation is requested, which can be triggered, for example, by the control unit 10, the second freewheel 9 is moved into the second state, in which the rotation of the output element 5 can be transferred to the electric motor 3 when the bicycle 2 is moving forward. In this state, the electric motor 3 is driven when the bicycle 2 is moving forward and can generate electrical power in this operating state. Simultaneously, the electric motor 3 generates a torque that acts as a braking force on the drive wheel 6 in the opposite direction of travel of the bicycle 2. The electrical power generated by the electric motor 3 is stored in the electrical energy storage device via a corresponding control unit.

[0028] Due to the design of the elements in the power transmission path between the output element 5 and the drive wheel 6, the drive force from the drive wheel 6 can be transferred to the electric machine 3 both during propulsion and in recuperation mode. The second freewheel 9 and its switchable design allow the bicycle 2 to be set to either a rolling state without recuperation or operation with recuperation, which involves the introduction of torque into the electric machine 3. Simultaneously, the first freewheel 8 prevents the crank assembly 4 from rotating without input from the rider of the bicycle 2 when the output element 5 rotates. This design thus provides a bicycle that can be propelled, at least temporarily, by muscle power, thereby fulfilling the function of an e-bike.Pedelecs can be provided and at the same time recuperation is enabled, while the application for the rider does not differ from that of an ordinary bicycle, particularly with regard to the operation of the crank device 4.

[0029] In the present embodiment, the transmission device 7 is provided with a system consisting of a sprocket, pinion, and chain. Other arrangements are conceivable, such as a belt drive or a cardan drive. Furthermore, in the present embodiment, the transmission device 7 is provided with a hub gear. However, the hub gear is not essential for the operation, and the provision of different gear ratios can be dispensed with. The in Fig. The assembly of the drive unit 1 shown in section 2 is merely an example.

[0030] More or fewer elements are conceivable, as long as the functionality described above is fulfilled.

[0031] In one embodiment, the recuperative operation is initiated by a signal from the control unit 10 provided for the drive unit 1. In an alternative embodiment, the recuperative operation is initiated by an input from the rider of the bicycle 2. Furthermore, in another alternative embodiment, the recuperative operation is initiated by a signal generated by a braking device of the bicycle 2, such that when the braking device of the bicycle 2 is applied, the second freewheel 9 is moved into the second state, thus enabling recuperative operation. Reference symbol 1 Drive unit 2 bicycles 3 Electric Machine 4 Crank mechanism 5 Starting element 6 drive wheel 7 Transmission device 8 First free run 9 Second freewheel 10 Control unit 11 Gear arrangement 12 Gear arrangement QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 4 273 033 A1

[0002]

Claims

[1] Drive device (1) for a bicycle (2) which can be operated at least temporarily with muscle power, comprising an electric machine (3) for providing a drive force, a crank device (4) for introducing muscle power, an output element (5) for delivering a combined drive force and a transmission device (7) for transmitting the combined drive force to the drive wheel (6), wherein a first freewheel (8) is provided between the crank device (4) and the output element (5) to enable the drive force from the crank device (4) to be introduced to propel the bicycle (2), wherein a second freewheel (9) is provided between the electric machine (3) and the output element (5), wherein the second freewheel is switchable such that in a first state of the second freewheel (9) a torque from the electric machine (3) to the output element (5) can only be transmitted in one direction of rotation for the propulsion of the bicycle (2) and in a second state of the second freewheel (9) a torque between the electric machine (3) and the output element (5) can be transmitted in both directions of rotation. [2] Drive device (1) according to claim 1, characterized by that a torque can be introduced into the electric machine (3) from the output element (5) when the second freewheel (9) is in the second state. [3] Drive device (1) according to claim 1 or 2, characterized bythat the drive device (1) can be operated in a recuperative mode when the second freewheel (9) is in the second state, so that a torque applied to the output element (5) is applied to the electric machine (3). [4] Drive device (1) according to claim 3, characterized by that the electrical machine (3) is operated as a generator in recuperative mode and generates electrical energy that can be used for storage when a torque is introduced by the output element (5). [5] Drive device (1) according to one of the preceding claims, characterized by that the second freewheel (9) is put into the second state by an instruction when there is a request for recuperation. [6] Bicycle (2) with a drive device (1) according to one of the preceding claims, wherein the bicycle (2) has a drive wheel (6) and a transmission device (7) for transmitting a torque between the drive device (1) and the drive wheel. [7] Bicycle (2) according to claim 6, characterized by that the transmission device (7) is designed to transmit a torque between an output element (5) of the drive device (1) and the drive wheel (6) both in a propulsion mode and in a thrust mode. [8] Bicycle (2) according to claim 6 or 7, characterized by that a torque transmission path between the output element (5) of the drive device (1) and the drive wheel (6) is designed without a freewheel. [9] Bicycle (2) according to one of claims 6 to 8, characterized bythat a hub gear is provided on the drive wheel (6), via which the drive wheel (6) is coupled to the drive device (1). [10] Bicycle (2) according to one of claims 6 to 9, characterized by that furthermore a control device (10) is provided which is designed to selectively control the state of the second freewheel (9) on the basis of an evaluation of an operating state of the bicycle (2) or on the basis of specifications by the rider in order to enable or prevent recuperative operation of the electric machine (3).

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