WO2023075659A1

WO2023075659A1 - An electric drive device for a bike

Info

Publication number: WO2023075659A1
Application number: PCT/SE2022/050946
Authority: WO
Inventors: Måns BENGTSSON
Original assignee: Zipforce Ab
Priority date: 2021-10-28
Filing date: 2022-10-19
Publication date: 2023-05-04

Abstract

The invention relates to an electric drive device (1) for a bike (2), the drive device (1) comprising: a transmission element (4), comprising an endless loop (6); a first sprocket (8) and a second sprocket (10), which are configured to engage with the transmission element (4), an electric motor (12) connected to the first sprocket (8) or the second sprocket (10), and which electric motor (12) is configured to rotate the first sprocket (8) or the second sprocket (10) and to cause a rotational motion of the transmission element (4); a hub wheel (14) configured to be connected to a drive wheel (16) of the bike (2), and which hub wheel (14) is configured to be driven by the transmission element (4). The hub wheel (14) is configured to engage with an outside (18) of the endless loop (6) of the transmission element (4). The invention further relates to a bike (2).

Description

An electric drive device for a bike

Technical field

The present disclosure relates to an electric drive device for a bike and a bike comprising such an electric drive device. More specifically, the disclosure relates to an electric drive device for a bike and a bike as defined in the introductory parts of claim 1 and claim 12.

Background art

Electric drive devices for bikes are used for the propulsion of bikes. They can be used as a complement to the traditional driveline of the bike or be the main propulsion source for the bike. There are electric bikes provided with a hub engine or a pedal crankcase engine. The hub engine always rotates with the bike wheel, which gives a braking effect, depending on the magnetic and electrical losses, whether or not the engine is required.

Further, there are known electric friction drive devices for electric bikes, which are in contact with the periphery of the front or rear bike wheel. An electric driven friction drive wheel arranged on the drive device is configured to abut the the periphery of the front or rear bike wheel. The friction drive wheel transmits its rotary motion to the bike wheel by friction.

Document W02020/037088 Al discloses an example of an electric motor bicycle system with an electric motor adapted to drive a wheel gear coupled to a hub of the bicycle. A motor driven gear is coupled to the wheel gear with a chain. The chain may be tensioned with one or more tensioners.

Summary

A problem with the solutions of the prior art drive devices is that the electric motor rotates with the bike wheel even though the electric motor do not proposing the bike. This may result in a braking effect on the bike, which reduces the speed of the bike.

There is thus a need for an improved electric drive device for a bike and for an improved bike comprising such an electric drive device.

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem. These objectives are achieved with the above-mentioned electric drive device for a bike and a bike comprising such an electric drive device according to the appended claims.

According to an aspect there is provided an electric drive device for a bike, the drive device comprising: a transmission element, comprising an endless loop; a first sprocket and a second sprocket, which are configured to engage with the transmission element, an electric motor connected to the first sprocket or the second sprocket, and which electric motor is configured to rotate the first sprocket or the second sprocket and to cause a rotational motion of the transmission element; a hub wheel configured to be connected to a drive wheel of the bike, and which hub wheel is configured to be driven by the transmission element, which hub wheel is configured to engage with an outside of the endless loop of the transmission element. The transmission element (4), together with the first sprocket (8) and the second sprocket (10), are pivotally arranged for connecting and disconnecting the transmission element (4) to and from the hub wheel (14).

Advantages of such electric drive device are that it is uncomplicated to arrange and mount the drive device on the bike. The electric drive device will contribute to the propulsion of the bike. Further, the engagement between the transmission element and the hub wheel may be released under circumstances when the electric drive device should not be used. Due to the disengagement, no braking effect on the bike from the electric drive device will occur, which may otherwise reduce the speed of the bike. The disengagement between the transmission element and the hub wheel is possible due to the fact that the hub wheel is configured to engage with an outside of the endless loop of the transmission element.

According to an aspect there is provided a bike, wherein the bike comprises the above- mentioned electric drive device.

Such bike will be easy to propel, when the transmission element and the hub wheel are in engagement and the electric drive device contributes to the propulsion of the bike, but also when the transmission element is disengaged from the hub wheel released under circumstances when the electric drive device should not be used. Due to the disengagement, no braking effect on the bike from the electric drive device will occur, which may otherwise reduce the speed of the bike.

The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.

Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

Brief of the

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

Fig. 1 schematically illustrates a side view of an electric drive device arranged at a front of a bike according to an example,

Fig. 2 schematically illustrates a side view of an electric drive device arranged at the rear of a bike according to an example,

Fig. 3 schematically illustrates a side view of an electric drive device arranged at the rear of a bike according to an example,

Fig. 4 schematically illustrates a side view of an electric drive device arranged at the rear of a bike according to an example,

Fig. 5 schematically illustrates a detail view of an electric drive device according to an example, and

Figures 6 and 7 schematically illustrate side views of a bike according to two examples. Detailed description

The present disclosure will now be described with reference to the accompanying drawings, in which preferred examples of the disclosure are shown. The disclosure may, however, be exemplified in other forms and should not be construed as limited to the herein disclosed examples. The disclosed examples are provided to fully convey the scope of the disclosure to the skilled person.

According to an aspect of the present disclosure, an electric drive device for a bike is provided. The electric drive device comprising: a transmission element, comprising an endless loop; a first sprocket and a second sprocket, which are configured to engage with the transmission element, an electric motor connected to the first sprocket or the second sprocket, and which electric motor is configured to rotate the first sprocket or the second sprocket and to cause a rotational motion of the transmission element; a hub wheel configured to be connected to a drive wheel of the bike, and which hub wheel is configured to be driven by the transmission element, which hub wheel is configured to engage with an outside of the endless loop of the transmission element. The transmission element, together with the first sprocket and the second sprocket, are pivotally arranged for connecting and disconnecting the transmission element to and from the hub wheel.

The electric drive device comprises the components, which together generates a propulsion of the bike. The device can be a complement to a manually propelled driveline of the bike, such as pedals, pedal crankcase, drive chain, a hub wheel and a drive wheel. Depending of the design of the device and the bike, the device may alternatively be a main propulsion source for the bike.

The bike may be a bicycle, a tricycle, a unicycle or a quadricycle comprising one or more drive wheels. The drive device may be mounted on any wheel of a bike. The wheel or wheels of the bike provided with the drive device may be defined as a drive wheel of the bike.

The transmission element is configured to transfer rotational motion and torque. The transmission element is an endless loop. The endless loop may be flexible. The endless loop is configured to take different shapes. The shape of the endless loop will adapt to the positions and the shapes of the first and second sprockets. A rotational motion and torque of the first sprocket will be transferred to the second sprocket by the endless loop of the transmission element. A rotational motion and torque of the second sprocket will be transferred to the first sprocket by the endless loop of the transmission element. The electric motor may be connected to the first sprocket or the second sprocket, and which electric motor is configured to rotate the first sprocket or the second sprocket and to cause a rotational motion of the transmission element. When the electric motor is connected to the first sprocket, the electric motor is configured to generate a rotational motion of the first sprocket. The rotational motion of the first sprocket will drive the transmission element. The transmission element driven by the first sprocket will generate a rotational motion of the second sprocket. Alternatively, when the electric motor is connected to the second sprocket, the electric motor is configured to generate a rotational motion of the second sprocket. The rotational motion of the second sprocket will drive the transmission element. The transmission element, driven by the second sprocket, will generate a rotational motion of the first sprocket.

The electric motor is connected to an electric power source. The electric power source may be a battery arranged on the bike. The battery may be rechargeable by an external power source. The battery may be rechargeable by the electric motor in a regeneration mode. The regeneration mode may occur during retardation of the bike, for example during a braking sequence to reduce the speed of the bike. The battery may be arranged on the front fork of the bike. The battery may be arranged on the frame of the bike. The battery may be arranged at the electric drive device. The battery and the electric drive device may be folded together similar to a folding knife, when folding the electric drive device from the engaged to the disengaged position.

The hub wheel may be arranged at the hub of the drive wheel. The hub wheel may be removable arranged at the drive wheel. A rotational motion of the hub wheel will result in a rotational motion of the drive wheel. The hub wheel and the transmission element are configured to engage with each other. The outside of the endless loop of the transmission element is configured to engage with a periphery of the hub wheel. The transmission element may be disengaged from the hub wheel by removing the transmission element from the hub wheel. The hub wheel may be arranged in parallel with a brake disc at the drive wheel. The hub wheel may have the same diameter as the brake disc or may have a different diameter than the brake disc. The hub wheel may be arranged at the same side of the drive wheel as the brake disc. The hub wheel may be arranged at the opposite side of the drive wheel as the brake disc. The hub wheel may be arranged in parallel with a bike cassette at the drive wheel. The hub wheel may be arranged at the same side of the drive wheel as the bike cassette. The hub wheel may be arranged at the opposite side of the drive wheel as the bike cassette. The electric drive device may be easy to arrange and mount on the bike. The engagement between the transmission element and the hub wheel may be released under circumstances when the electric drive device should not be used. Due to the disengagement or disconnection of the transmission element from the hub wheel, no braking effect on the bike from the electric drive device will occur, which may otherwise reduce the speed of the bike. The disengagement between the transmission element and the hub wheel is possible due to the fact that the hub wheel is configured to engage with an outside of the endless loop of the transmission element. However, during circumstances when the transmission element is engaged with the hub wheel, the battery for propulsing the electric motor may be rechargeable by the electric motor in a regeneration mode. In the regeneration mode the electric motor works as a generator.

The electric drive device may be connectable to and releasable from the bike by means of a connectable and releasable attachment device. This will facilitate maintenance of the electric drive device and prevent theft of the electric drive device.

The transmission element, the first sprocket and the second sprocket may be pivotally arranged on the bike. Pivoting the transmission element, the first sprocket and the second sprocket as a unit in relation to the hub wheel may connect or disconnect the endless loop of the transmission element to or from the hub wheel. A pivotation of the transmission element, the first sprocket and the second sprocket in a first direction may connect the endless loop of the transmission element with the hub wheel, so that the endless loop engage with the hub wheel. A pivotation of the transmission element, the first sprocket and the second sprocket in a second direction may disconnect the endless loop of the transmission element from the hub wheel. Pivoting the transmission element, the first sprocket and the second sprocket together, may be performed manually, electrically, pneumatically and/or hydraulically. A manually pivoting of the transmission element, the first sprocket and the second sprocket together, may be performed by controlling a control lever connected to the electric drive device by a wire. In the engaged position of the endless loop and the hub wheel, the transmission element, the first sprocket and the second sprocket as a unit may be spring loaded, so that the endless loop of the transmission element abuts and engages the hub wheel by a force from the spring.

According to an aspect, the first sprocket and the second sprocket are configured to engage with an inside of the endless loop of the transmission element.

The motion of one of the first or second sprocket will be transferred to the other sprocket by the endless loop of the transmission element. A rotational motion and torque of the first sprocket will be transferred to the second sprocket by the endless loop of the transmission element. A rotational motion and torque of the second sprocket will be transferred to the first sprocket by the endless loop of the transmission element. The first or second sprocket may be arranged at a fixed or adjustable distance to each other, and the length or the circumference of the endless loop may be adapted the distance between the first and second sprocket. The arrangement of the first and second sprocket inside of the endless loop will secure the position of the transmission element and prevent the transmission element do be disengaged from the first and second sprocket.

According to an aspect, the transmission element, together with the first sprocket and the second sprocket, are pivotally arranged about a center axis of the first sprocket or the second sprocket.

The arrangement of a pivoting axis of the transmission element, the first sprocket and the second sprocket as a unit, coinciding with the center axis of the first sprocket will create a compact drive device, which is concentrated to the hub area of the drive wheel of the bike. In addition, the first sprocket is arranged on a shaft, which may be rotatably mounted in the front fork or the frame of the bike. The transmission element, the first sprocket and the second sprocket as a unit may be pivotally arranged about the shaft of the first sprocket. Alternatively, arranging the pivoting axis of the transmission element, the first sprocket and the second sprocket as a unit, coinciding with the center axis of the second sprocket will create a compact drive device, which is concentrated to the hub area of the drive wheel of the bike. In addition, the second sprocket is arranged on a shaft, which may be rotatably mounted in the front fork or the frame of the bike. The transmission element, the first sprocket and the second sprocket as a unit may be pivotally arranged about the shaft of the second sprocket.

According to an aspect, the electric motor is configured to generate a pivotal motion of the transmission element, the first sprocket and the second sprocket for connecting and disconnecting the transmission element to and from the hub wheel.

The electric motor is connected to the first sprocket and configured to rotate the first sprocket. The rotational motion of the electric motor may also be used to pivote the transmission element, the first sprocket and the second sprocket as a unit in relation to the hub wheel for connecting or disconnecting the endless loop of the transmission element to or from the hub wheel. The rotational direction of the electric motor may control the pivotal direction of the transmission element, the first sprocket and the second sprocket. Rotating the electric motor in a first direction in order to engage the endless loop of the transmission element with the hub wheel and for propelling the bike may also pivot the transmission element, the first sprocket and the second sprocket as a unit in the direction of the hub wheel. In order to disengage the endless loop of the transmission element with the hub wheel the electric motor is switched to rotate in a second rotational direction, which is opposite to the first rotational direction. This will result in that the transmission element, the first sprocket and the second sprocket as a unit will pivot in the direction from the hub wheel.

According to an aspect, the first sprocket and the second sprocket are rotatably arranged on a guide bar.

The guide bar may arrange the first or second sprocket at a fixed or adjustable distance to each other. The first sprocket and the second sprocket may be rotatably arranged on the guide bar by bearings. The guide bar may together with the transmission element, the first sprocket and the second sprocket be pivotally arranged for connecting and disconnecting the transmission element to and from the hub wheel.

According to an aspect, a tensioning mechanism is arranged on the guide bar for tensioning the endless loop of the transmission element.

The distance between the first and second sprocket may be adjustable in order to tension the endless loop of the transmission element. The tension of the transmission element will keep the endless loop in place and in engagement with the first and second sprocket. Further, the tension of the transmission element will adapt the shape of the endless loop to the shape and radius of the hub wheel, which will result in an engagement between the transmission element and the hub wheel when they are connected. The tensioning mechanism may be a mechanical spring, or a hydraulic, pneumatic or electric controlled actuator.

According to an aspect, the hub wheel is a brake disc, which is provided with peripheral arranged engagement elements, which are configured to engage with the transmission element.

The brake disc is firmly connected to the wheel of the bike. Each wheel of the bike may be provided with a brake disc. The brake disc may be provided with a caliper and brake pads. In addition, the brake disc is provided with peripheral arranged engagement elements, which are configured to engage with the transmission element. The transmission element is configured to transmit the rotational motion and torque from the electric motor to the brake disc for generating a rotational motion of the drive wheel and thus propelling the bike. According to an aspect, the hub wheel is a bike cassette of a powertrain of the bike.

The bike cassette is a transmission element in the powertrain of the bike. The cassette may comprise a number of sprockets of different diameters arranged on the rear wheel of the bike. The bike cassette offers a number of different gears of different gear ratios. The transmission element is configured to transmit the rotational motion and torque from the electric motor to one or a number of the sprockets of the cassette for generating a rotational motion of the drive wheel and thus propelling the bike. The drive device may be configured to select between the different sprockets on the cassette in order to select different gear ratios for propelling the bike.

According to an aspect, the transmission element is a drive chain.

The drive chain may be a conventional bike chain, which comprises a number of links, which are pivotally arranged in relation to each other. The first and second sprocket of the drive device and the hub wheel are provided with teeth for engagement with the drive chain.

According to an aspect, the transmission element is a toothed belt.

The toothed belt is a flexible, endless loop, which is provided with a number of inwardly directed teeth. In addition, the toothed belt is provided with a number of outwardly directed teeth. The inwardly directed teeth on the toothed belt are configured to engage with peripheral arranged teeth on the first and second sprockets. The outwardly directed teeth on the toothed belt are configured to engage with peripheral arranged teeth on the hub wheel.

According to a further aspect of the present disclosure there is provided a bike, wherein the bike comprises an electric drive device disclosed herein.

The bike may be a bicycle, a tricycle, a unicycle or a quadricycle comprising one or more drive wheels. The drive device may be mounted on any wheel of a bike. The wheel or wheels of the bike provided with the drive device may be defined as a drive wheel of the bike. Such bike will be easy to propel, when the transmission element and the hub wheel are in engagement and the electric drive device contributes to the propulsion of the bike, but also when the transmission element is disengaged from the hub wheel released under circumstances when the electric drive device should not be used. Due to the disengagement, no braking effect on the bike from the electric drive device will occur, which may otherwise reduce the speed of the bike. According to an aspect, the electric drive device is configured to be pivotally connected to a front fork and/or to a frame of the bike.

The transmission element, the first sprocket and the second sprocket of the drive device may be pivotally connected to a front fork and/or to a frame of the bike. Such a configuration may allow for a number of driving devices arranged on the bike. Pivoting the transmission element, the first sprocket and the second sprocket as a unit in relation to the hub wheel may connect or disconnect the endless loop of the transmission element to or from the hub wheel. A pivotation of the transmission element, the first sprocket and the second sprocket in a first direction may connect the endless loop of the transmission element with the hub wheel, so that the endless loop engage with the hub wheel. A pivotation of the transmission element, the first sprocket and the second sprocket in a second direction may disconnect the endless loop of the transmission element from the hub wheel. Pivoting the transmission element, the first sprocket and the second sprocket together, may be performed manually, electrically, pneumatically and/or hydraulically. In the engaged position of the endless loop and the hub wheel, the transmission element, the first sprocket and the second sprocket as a unit may be spring loaded, so that the endless loop of the transmission element abuts and engages the hub wheel by a force from the spring.

The transmission element, together with the first sprocket and the second sprocket, may be pivotally arranged about a center axis of the first sprocket. The center axis of the first sprocket and the second sprocket may be parallel to the center axis of the drive wheel of the bike. The electric motor may be connected to the first or the second sprocket. The electric motor is configured to generate a pivotal motion of the first or the second sprocket. The pivotal motion of the first or second sprocket may drive the transmission element and thus generating a pivotal motion of the other sprocket. The hub wheel and the transmission element may be engaged with each other. The hub wheel may be a bike cassette of a powertrain of the bike. The bike cassette my comprise a number of sprockets of different diameters. The transmission element may be axially displaceable along the center axis of the first and second sprocket. The axially displacement is performed by a displacement arrangement. The control lever may control the displacement arrangement. A wire may be configured to transfer a movement from the control lever to the displacement arrangement. When displacing the displacement arrangement axially, the transmission element may be moved from one sprocket of the bike cassette to another sprocket of the bike cassette, which may result in a gear shifting. The displacing arrangement may be connected to control device, which may control the axially displacement of the displacement arrangement and thus the shifting of gears. A tension sensor may be arranged to sense the tension of the transmission chain for propelling the bike. The tension sensor may be connected to the control device. In case the control device receives a signal from the tension sensor that the tension of the transmission chain is low, the control device may control the electric motor to a speed adapted to the propelling speed generated by the transmission chain.

The drive device for a bike will now be described together with the appended drawings.

Fig. 1 schematically illustrates a side view of an electric drive device 1 arranged at a front of a bike 2 according to an example. The drive device 1 comprising a transmission element 4, comprising an endless loop 6. A first sprocket 8 and a second sprocket 10 are configured to engage with the transmission element 4. An electric motor 12 is connected to the first sprocket 8 and which is configured to rotate the first sprocket 8 and to cause a rotational motion of the transmission element 4. A hub wheel 14 is configured to be connected to a drive wheel 16 of the bike 2, and which hub wheel 14 is configured to be driven by the transmission element 4. The hub wheel 14 is configured to engage with an outside 18 of the endless loop 6 of the transmission element 4. The hub wheel 14 and the transmission element 4 are engaged with each other in fig. 1.

The first sprocket 8 and the second sprocket 10 are configured to engage with an inside 20 of the endless loop 6 of the transmission element 4. The transmission element 4, together with the first sprocket 8 and the second sprocket 10, are pivotally arranged for connecting and disconnecting the transmission element 4 to and from the hub wheel 14. In fig. 1, the hub wheel 14 is a brake disc 14, which is provided with peripheral arranged engagement elements 28, which are configured to engage with the transmission element 4. The first sprocket 8 and the second sprocket 10 are rotatably arranged on a guide bar 24. The transmission element 4 may be a drive chain or a toothed belt.

A manually pivoting of the transmission element 4, the first sprocket 8 and the second sprocket 10 together, may be performed by controlling a control lever 25 (fig. 6) connected to the electric drive device 1 by a wire 27.

Fig. 2 schematically illustrates a side view of an electric drive device 1 arranged at the rear of a bike 2 according to an example. The transmission element 4, the first sprocket 8, the second sprocket 10, the guide bar 24 and the electric motor 12 has been pivoted, so that the endless loop 6 of the transmission element 4 is disconnected from the hub wheel 14. According to fig. 2, the hub wheel 14 is a bike cassette 14 of a powertrain 30 of the bike 2.

Fig. 3 schematically illustrates a side view of an electric drive device arranged at a rear of a bike according to an example. According to this example, the transmission element 4, together with the first sprocket 8 and the second sprocket 10, are pivotally arranged about a center axis 22 of the first sprocket 8. The electric motor 12 is configured to generate a pivotal motion of the transmission element 4, the first sprocket 8 and the second sprocket 10 for connecting and disconnecting the transmission element 4 to and from the hub wheel 14. In fig. 3, the hub wheel 14 and the transmission element 4 are engaged with each other.

Fig. 4 schematically illustrates a side view of an electric drive device arranged at a rear of a bike according to an example. According to this example, the transmission element 4, together with the first sprocket 8 and the second sprocket 10, are pivotally arranged about a center axis 22 of the first sprocket 8. The center axis 22 of the first sprocket 8 may be parallel to the center axis of the bike wheel. The electric motor 12 is connected to the second sprocket 10. The electric motor 12 is configured to generate a pivotal motion of the second sprocket 10. The pivotal motion of the second sprocket 10 will drive the transmission element 4 and thus generating a pivotal motion of the first sprocket 8. In fig. 4, the hub wheel 14 and the transmission element 4 are engaged with each other. The hub wheel 14 in fig. 4 is a bike cassette 14 of a powertrain 30 of the bike 2. The bike cassette 14 comprises a number of sprockets of different diameters. The transmission element 4 may be axially displaceable along the center axis 22. The axially displacement is performed by a displacement arrangement 40. The control lever 25 (fig. 6) may control the displacement arrangement 40. A wire 42 is configured to transfer a movement from the control lever 25 to the displacement arrangement 40. When displacing the displacement arrangement axially, the transmission element may be moved from one sprocket of the bike cassette 14 to another sprocket of the bike cassette 14, which will result in a gear shifting. The displacing arrangement 40 may be connected to control device 44, which may control the axially displacement of the displacement arrangement 40 and thus the shifting of gears. A tension sensor 46 may be arranged to sense the tension of the transmission chain 48 for propelling the bike 2. The tension sensor 46 may be connected to the control device 44. In case the control device 44 receives a signal from the tension sensor 46 that the tension of the transmission chain 48 is low, the control device 44 may control the electric motor 12 to a speed adapted to the propelling speed generated by the transmission chain 48. The transmission element 4 according to the example in fig. 2 and fig. 3 may also be axially displaceable along the center axis 22, and thus also be provided with the displacement arrangement 40, the wire 42, the control lever 25, the control device 44, the tension sensor 46 and the transmission chain 48, with the functions described in connection with the example of fig. 4.

Fig. 5 schematically illustrates a detail view of an electric drive device according to an example. The guide bar is provided with an opening for pivotal connection to the bike. In an opposite end of the guide bar, a pin or a handle for manually pivoting the guide bar about the pivotal connection of the guide bar to the bike. The electric motor is arranged on the guide bar and connected to the first sprocket. The transmission element 4 is arranged to engage with the first and second sprockets. A tensioning mechanism 26 is arranged on the guide bar 24 for tensioning the endless loop 6 of the transmission element 4.

Figures 6 and 7 schematically illustrate side views of a bike 2 according to two examples. In fig. 6, the electric drive device is arranged at a front fork of the bike 2. In fig. 7 the electric drive device is arranged at a frame of the bike 2. The electric drive device 1 is configured to be pivotally connected to the front fork 32 of the bike 2 in fig. 6 and to the frame 34 of the bike 2 in fig. 7. A battery 36 is connected to the front fork 32 of the bike 2 in fig. 5 and to the frame 34 of the bike 2 in fig. 6 in order to deliver electric power to the drive device 1. The battery 36 may alternatively be connected to the front fork 32 of the bike 2 in fig. 7 and to the frame 34 of the bike 2 in fig. 6. For manually pivoting of the transmission element 4, the first sprocket 8 and the second sprocket 10 together, a control lever 25 is arranged on the bike 2.

The foregoing description of the embodiments has been furnished for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the embodiments to the variations described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order to best explicate principles and practical applications, and to thereby enable one skilled in the arts to understand the invention in terms of its various embodiments and with the various modifications that are applicable to its intended use. The components and features specified above may, within the frame work of the disclosure, be combined between different embodiments specified.

Claims

1. An electric drive device (1) for a bike (2), the drive device (1) comprising: a transmission element (4), comprising an endless loop (6); a first sprocket (8) and a second sprocket (10), which are configured to engage with the transmission element (4), an electric motor (12) connected to the first sprocket (8) or the second sprocket (10), and which electric motor (12) is configured to rotate the first sprocket (8) or the second sprocket (10) and to cause a rotational motion of the transmission element (4); a hub wheel (14) configured to be connected to a drive wheel (16) of the bike (2), which hub wheel (14) is configured to be driven by the transmission element (4); and which hub wheel (14) is configured to engage with an outside (18) of the endless loop (6) of the transmission element (4); characterised in that the transmission element (4), together with the first sprocket (8) and the second sprocket (10), are pivotally arranged for connecting and disconnecting the transmission element (4) to and from the hub wheel (14).

2. The drive device (1) according to claim 1, wherein the first sprocket (8) and the second sprocket (10) are configured to engage with an inside (20) of the endless loop (6) of the transmission element (4).

3. The drive device (1) according to any one of claims 1 and 2, wherein the transmission element (4), together with the first sprocket (8) and the second sprocket (10), are pivotally arranged about a center axis (22) of the first sprocket (8) or the second sprocket (10).

4. The drive device (1) according to claim 34, wherein the electric motor (12) is configured to generate a pivotal motion of the transmission element (4), the first sprocket (8) and the second sprocket (10) for connecting and disconnecting the transmission element (4) to and from the hub wheel (14).

5. The drive device (1) according to any one of the preceding claims, wherein the first sprocket (8) and the second sprocket (10) are rotatably arranged on a guide bar (24).

6. The drive device (1) according to claim 5, wherein a tensioning mechanism (26) is arranged on the guide bar (24) for tensioning the endless loop (6) of the transmission element (4).

7. The drive device (1) according to any one of the preceding claims, wherein the hub wheel (14) is a brake disc (14), which is provided with peripheral arranged engagement elements (28), which are configured to engage with the transmission element (4).

8. The drive device (1) according to any one of claims 1 - 6, wherein the hub wheel (14) is a bike cassette (14) of a powertrain (30) of the bike (2).

9. The drive device (1) according to any one of the preceding claims, wherein the transmission element (4) is a drive chain.

10. The drive device (1) according to any one of claims 1 - 6, wherein the transmission element (4) is a toothed belt.

11. A bike (2), wherein the bike (2) comprises an electric drive device (1) according to any one of the preceding claims.

12. The bike (2) according to claim 11, wherein the electric drive device (1) is configured to be pivotally connected to a front fork (32) and/or to a frame (34) of the bike (2).