One-way clutch system for vehicle

Abstract

The invention relates to a one-way clutch system of a vehicle, in particular of an electric bicycle, comprising a gearwheel, an output shaft, a one-way clutch, a friction element and a housing, the one-way clutch being designed to cause a torque transmission from the gearwheel to the output shaft when the gearwheel and the output shaft are rotated relative to each other in a locking direction, the transmission of torque is prevented when the gear and the output element rotate relative to each other in the free running direction, and wherein the friction element is designed to generate a predetermined friction torque between the gear and the housing.

Description

Field of the Invention

[0001] The present invention relates to a one-way clutch system (Freilaufanordnung) for a vehicle and to a vehicle. Background Art

[0002] In vehicles, such as for example electric bicycles, one-way clutches have hitherto been known which are designed to interrupt the connection between a driven output element and a motor transmission connected to a drive motor if the driven output element rotates faster with respect to the forward-pointing direction of rotation than the output of the motor transmission, that is to say in the direction of rotation which the drive of the vehicle causes in the forward-pointing driving direction. In the case of alternating mechanical loads in the drive train, such as for example due to vibrations at the chain which can occur when driving on uneven sections of road and which can lead to alternating rotational movements at the sprocket and thus at the output element, undesired noises can occur due to the existing transmission clearances. Summary of the Invention

[0003] In contrast, the one-way clutch system according to the invention with the features of claim 1 is distinguished by a particularly advantageous structure which enables a particularly efficient avoidance of noise with easy manufacturability. This is achieved according to the invention by a one-way clutch system for a vehicle, preferably an electric bicycle, which one-way clutch system comprises a gear, an output shaft, a one-way clutch, a friction element and a housing. The one-way clutch is designed to effect torque transmission from the gear to the output shaft when the gear and the output shaft rotate relative to one another in the locking direction, in particular by the one-way clutch itself. When the gear and the output element rotate relative to one another in the free-running direction (Freilaufrichtung), which is preferably opposite to the locking direction, the one-way clutch prevents torque transmission between the gear and the output shaft. Here, the friction element is configured to generate a predeterminable frictional torque between the gear and the housing.

[0004] In particular, the output shaft can be connected to a further drive train of the vehicle, for example via a sprocket and preferably a chain.

[0005] The housing can be, for example, a housing for holding and / or supporting the components of the one-way clutch system and, for example, further components of the vehicle. Preferably, the gear and the output shaft are rotatably supported in the housing. In other words, the housing is a stationary part relative to which the gear and the output shaft are rotatably arranged.

[0006] In other words, a one-way clutch system is provided, which has a one-way clutch between a gear and an output shaft. The gear can form, for example, the last gear of a transmission mechanism of a vehicle's drive system, and in particular transmits an output torque, which is provided, for example, for propelling the vehicle, to the output shaft. A friction element is provided between the fixed housing and the gear, which causes a predetermined frictional torque between the gear and the housing. For example, as long as the frictional torque or the frictional force is not exceeded, the gear is fixed relative to the housing by the frictional torque, in particular with a corresponding predetermined frictional force.

[0007] The advantage provided by the one-way clutch system here is that alternating external rotational impulses that may occur at the output shaft and are transmitted to the gear via the one-way clutch do not negatively affect the noise generation at the gear. Specifically, especially when the gear is in tooth engagement with another gear, by means of the additional frictional torque caused by the friction element, it can be ensured that the load-bearing tooth flank of the gear is always in engagement. That is to say, the following tooth flank of the gear remains in engagement even in the case of a rotation in the opposite direction of the output shaft by the frictional torque, and this tooth flank can be in engagement with, for example, another transmission gear when transmitting torque from the gear via the one-way clutch to the output shaft. That is to say, the additional frictional torque of the friction element prevents the gear from being dragged along due to, for example, the free-running friction of the one-way clutch in the free-running direction. If an external rotational impulse is then introduced into the gear via the one-way clutch, this external rotational impulse is further transmitted directly through the existing contact at the load-bearing tooth flank of the gear, for example, directly into the transmission mechanism. Therefore, by means of the friction element, it can be prevented that, in the case of an alternating direction of rotation in the drive train, for example due to chain vibrations caused by uneven ground, the tooth flanks at the bicycle alternately impact against each other by overcoming the backlash. Subsequently, noise generation, such as, for example, "clicking", can thus be avoided.

[0008] The dependent claims relate to preferred refinements of the invention.

[0009] Preferably, the one-way clutch system includes at least one pair of friction elements that are diametrically opposed with respect to the output shaft. Particularly preferably, the one-way clutch system includes two pairs of friction elements, that is, a total of four friction elements, which are arranged, in particular, evenly distributed around the circumference. Thereby, the friction elements can be generated particularly evenly and purposefully. In particular, disturbing or negatively acting forces and torques can be avoided.

[0010] Particularly preferably, the friction element is configured to generate a frictional torque by means of a radial frictional force. In other words, the friction element is configured to cause a radial frictional force and thus, in particular, to cause a frictional torque between the gear and the housing by means of a corresponding radial frictional engagement. Thus, a frictional torque can be generated by means of a particularly simple and cost-effective structure. In a design with a radial frictional force, particularly when the radial frictional force is applied symmetrically with respect to the output axis of the output shaft, it is particularly advantageous that the necessary forces for friction cancel each other out and thus no additional force component occurs between the one-way clutch and the shaft, which additional force component would, for example, lead to additional friction that would act against the desired frictional torque between the gear and the housing.

[0011] Preferably, the friction element is configured to generate a frictional torque by means of an axial frictional force. In other words, the friction element is configured to cause an axial frictional force and thus, in particular, to cause a frictional torque between the gear and the housing by means of a corresponding axial frictional engagement. Thus, for example, a frictional torque can be provided by means of a structure that is particularly space-saving in the radial direction.

[0012] Preferably, the friction element has a friction arm and a friction ring. The friction arm and the friction ring are in mechanical contact with each other here in order to generate a frictional torque by means of this mechanical contact. In other words, the friction element is at least two-piece and includes preferably at least one friction arm and a friction ring. For example, a plurality of friction arms can also be provided. In particular, a protruding, at least partially elastically flexible member can be regarded as a friction arm, which presses against the friction ring, in particular by means of an elastic force. Thus, a predetermined frictional torque can be generated particularly reliably in a simple and cost-effective structure.

[0013] Further preferably, in particular at least one friction arm is fixed to the gear, wherein the friction ring is fixed to the housing. The friction arm can, for example, be fixed in a region of the gear that is radial within the tooth section and is, for example, at least partially constructed to protrude in the axial direction. The friction ring can, for example, be an integral component of the housing or alternatively is preferably constructed as an additional member fixed to the housing. Thus, a particularly simple and cost-effective structure and manufacturability of the one-way clutch system can be achieved.

[0014] Preferably, in particular at least one friction arm is fixed to the housing, wherein the friction ring is fixed to the gear. The friction arm can, for example, be an integral component of the housing or alternatively is constructed as an additional member fastened to the housing. Further preferably, the friction ring can be an integral component of the gear or alternatively is preferably constructed as an additional member fixed to the gear.

[0015] The friction arm is particularly preferably configured in a plate-like manner. In particular, the friction arm is entirely composed of a plate, preferably a metal plate. Thereby, easy manufacturability with a flexible geometry can be achieved. In addition, elastic flexibility can be provided in an easy manner in order to establish mechanical contact for the frictional torque by means of an elastic spring force.

[0016] Furthermore, it is preferred that the friction arm has a base region and at least one friction region. The friction region extends in the circumferential direction starting from the base region. The friction region has a friction surface here, which is in mechanical contact with the friction ring in order to generate a frictional torque. For example, a point contact can be provided between the friction surface and the friction ring. Alternatively, it is preferred that a line contact or a surface contact can be configured. It is preferred that the friction arm has two friction regions. The two friction regions are arranged opposite each other and extend in the circumferential direction starting from the base region. Each of the friction regions in the friction regions has a friction surface here. Thereby, a particularly easy and cost-effective structure of the friction element can be provided in order to reliably and in a defined manner establish a frictional engagement between the gear and the output shaft.

[0017] The one-way clutch is preferably configured as a pinch roller one-way clutch. Thereby, a reliable free-running function and a stop function can be provided in the case of an easy and particularly cost-effective structure.

[0018] Alternatively, it is preferred that the one-way clutch can also be configured in other ways, for example as a wedge one-way clutch or as an independent spring-loaded one-way clutch or as a centrally spring-loaded one-way clutch.

[0019] In addition, the invention relates to a vehicle, preferably an electric bicycle, which includes the described one-way clutch system.

[0020] Preferably, the vehicle further includes a drive unit and a crank drive, the drive unit is connected to the gear, in particular for torque transmission, and the crank drive is connected to the crankshaft, in particular against rotation. In particular, the one-way clutch is thus arranged between the transmission of the drive unit and the output shaft, which in particular forms the pedal shaft or the crankshaft of the vehicle. The one-way clutch can also be referred to as a motor one-way clutch, for example. Description of the Drawings

[0021] The present invention will be described below with reference to embodiments in conjunction with the drawings. In the drawings, functionally identical components are each denoted by the same reference numeral. The following are shown:

[0022] Figure 1 A simplified schematic view of a vehicle having a one-way clutch system according to a first embodiment of the present invention is shown,

[0023] Figure 2 It is shown Figure 1 A detailed cross-sectional view of the one-way clutch system of

[0024] Figure 3 A perspective view showing the details of the one-way clutch system of Figure 1

[0025] Figure 4 A detailed cross-sectional view showing the one-way clutch system according to the second embodiment of the present invention,

[0026] Figure 5 A perspective view showing Figure 4 the details of the one-way clutch system of

[0027] Figure 6 A detailed cross-sectional view showing the one-way clutch system according to the third embodiment of the present invention, and

[0028] Figure 7 A detailed simplified schematic view showing the working principle of the one-way clutch system according to the present invention. Detailed Description of the Invention

[0029] Figure 1 A simplified schematic view of a vehicle 100 is shown, which vehicle includes a one-way clutch system 1 according to the first embodiment of the present invention. The vehicle 100 is a vehicle 100 that can be operated using muscular force and / or motor force, specifically an electric bicycle.

[0030] The electric bicycle 100 includes a drive unit 102, which drive unit includes a motor, in particular an electric motor. The motor can be supplied with electrical energy by means of an electrical energy storage device 109 of the electric bicycle 100.

[0031] The drive unit 102 is arranged in the region of the pedal bearing of the electric bicycle 100. The motor torque generated by means of the motor can motor-drivingly support the pedal force generated by the driver of the electric bicycle 100 by muscular force.

[0032] The muscular force of the driver can here be applied to the output shaft 3 by means of a crank drive mechanism 104 including a crank. The output shaft 3 extends along an output axis 30. The gear 2 of the drive unit 102 is arranged coaxially with the output shaft 3 (see Figure 2 and Figure 3 ).

[0033] The gear 2 here forms the last gear of a (not shown) transmission mechanism of the drive unit 102. By means of the transmission mechanism, the motor can transmit the pedal torque to the gear 2.

[0034] The output shaft 3 further includes a connection region 108, to which an output element 107, in particular a sprocket, is non-rotatably fastened (see Figure 1 ).

[0035] The one-way clutch 4 is disposed between the gear 2 and the output shaft 3, and in the illustrated embodiment, the one-way clutch is configured as a pinch roller type one-way clutch. When the gear 2 rotates relative to the output shaft 3 (see Figure 3 ) in the stop direction 42, the one-way clutch 4 stops and causes torque transmission between the gear 2 and the output shaft 3. When the gear 2 rotates relative to the output shaft 3 in the opposite free-running direction 41, the one-way clutch 4 releases rotation and prevents torque transmission.

[0036] It should be noted that in the drawings, the "free-running direction 41" and the "stop direction 42" are defined and shown from the perspective of the gear 2. For example, from the perspective of the output shaft 3, directions opposite in spirit will be obtained with respect to the release and stop of the one-way clutch 4.

[0037] In the case where the one-way clutch 4 is stopped, the drive unit 102 can drive the output shaft 3 via the gear 2 and the one-way clutch 4 by means of the generated motor torque.

[0038] Furthermore, the drive unit 102 includes a housing 6, which is provided for receiving and holding the components of the drive unit 102 and the one-way clutch system 1. In addition, the housing 6 can be provided for being assembled to the bicycle frame of the electric bicycle 100.

[0039] In particular, the output shaft 3 is rotatably supported in the housing 6 by a pedal bearing 9.

[0040] The one-way clutch system 1 further includes a friction element 5 configured in a multi-piece manner. The friction element 5 includes a plurality of friction arms 51 and a friction ring 52.

[0041] The friction ring 52 is preferably configured as a metal ring, which is in particular configured as an independent component and fixed to the bearing sleeve of the housing 6.

[0042] The friction arms 51 are configured in a plate shape and fixed to the gear 2. Here, the friction arms 51 are arranged diametrically opposite with respect to the output axis 30.

[0043] In detail, each friction arm 51 has a fastening region 51d, which is fixed, for example, by a welding connection to the axial end side of the gear 2. In addition, each friction arm has a base region 51a, which extends substantially in the axial direction starting from the fastening region 51d. In addition, each friction arm 51 has two friction regions 51b, which are respectively arranged oppositely and extend in the circumferential direction starting from the base region 51a. Here, a friction surface 51c is formed at each friction region 51b, and the friction surface is in mechanical contact with the radially inner friction ring 52.

[0044] The friction arms 51 are designed in this case so as to press radially inwards against the friction ring 52 with a predetermined radial friction force 45a (see Figure 2 ). When gear 2 and output shaft 3 rotate relative to each other (see Figure 3 ), thereby generating a predetermined increased friction torque 45 in a targeted manner. In particular, when the gear 2 and the output shaft 3 are stationary or generally when the gear 2 and the output shaft 3 do not rotate relative to each other, the friction torque 45 is generated by the static friction between the friction ring 53 and the friction arm 51. Figure 3 2 is shown as an example, which does not rotate relative to the housing 6. When the gear 2 rotates relative to the output shaft 3 in the free running direction 41, the friction lock between the gear 2 and the housing 6 generated by the friction element 5 causes a friction torque 45 that acts in the opposite direction of the free running direction 41.

[0045] The friction torque 45 causes the tooth flanks of the gear 2 which are in meshing during the torque transmission during the rotation in the locking direction 42 to remain in meshing even when the output shaft 3, in particular at least briefly, performs such a rotation for releasing the freewheel 4, which can occur, for example, due to chain vibrations caused by uneven ground. Such a rotation, for example, according to the above definition and Figure 3 This will be similar to the rotation of the gear 2 in the free-running direction 41 relative to the output shaft 3 .

[0046] For example, Figure 7 The tooth side in meshing is shown in FIG. Figure 7 The tooth engagement between the gear wheel 2 of the drive unit 102 and a further gear wheel 25 is shown. For example, a torque generated by a motor is transmitted from the gear wheel 25 to the gear wheel 2. The tooth flanks of the two gear wheels 2, 25 are in contact with each other at the tooth engagement point 27.

[0047] The friction torque 45 ensures that the tooth flanks of the two gears 2, 25 always remain in contact with each other at the tooth meshing point 27, even if the output shaft 3 rotates relative to the gear 2, which would cause the one-way clutch 4 to open. This prevents the gears 2, 25 from moving relative to each other and the opposing tooth flanks that are not in meshing from hitting each other. Unwanted noises due to undesired tooth flank collisions can be avoided. For example, "clicking" of the transmission can be avoided.

[0048] The preferred friction element 5 is designed such that the resulting frictional torque 45 is greater than the free-running frictional torque (Freilauf-Reibmoment) transmitted by the one-way clutch 4 in the free-running direction 41. That is, the frictional torque 45 additionally generated by means of the friction element 5 prevents the gear 2 from being dragged along due to the free-running frictional torque present in the one-way clutch 5 when the output shaft 3 rotates relative to the gear 2 in the clockwise direction (which is analogous to the gear 2 rotating relative to the output shaft 3 in the free-running direction 41), which would lead to alternating flank collisions. Thus, by means of the one-way clutch system 1, a particularly low-noise operating mode of the drive system 102 can be provided in the case of a particularly simple and cost-effective structure.

[0049] Figure 4 A detailed cross-sectional view of the one-way clutch system 1 according to a second embodiment of the invention is shown. In Figure 5 is shown Figure 4 a perspective view of the details of the one-way clutch system 1. The second embodiment basically corresponds to Figures 1 to 3 the first embodiment, wherein the difference lies in an alternative design and arrangement of the friction element 5. In the second embodiment, the friction arm 51 is fixed to the housing 6. The friction ring 52 is here an integral component of the gear 2. In particular, the gear 2 and the friction ring 52 can thus be constructed as a common integral component. Thereby, alternative geometries and structures can be provided, which allow for easy and cost-effective manufacturing.

[0050] Figure 6 A detailed cross-sectional view of the one-way clutch system 1 according to a third embodiment of the invention is shown. The third embodiment basically corresponds to Figure 4 and Figure 5 the second embodiment, wherein the difference lies in an alternative design of the friction element 5 such that an axial frictional force 45b is generated instead of the radial frictional force 45a. Here, the friction arm 51 is fastened to the housing 6 such that the friction arm presses axially, in particular elastically, against the axial end face of the gear 2 which thus forms the friction ring 52. Thereby, additional alternative structures and geometries can be provided, which offer advantageous functionality and manufacturability.

Claims

1. A one-way clutch system for a vehicle (100), in particular an electric bicycle, the one-way clutch system comprising: - gear (2), - output shaft (3), - one-way clutch (4), - a friction element (5), and - a housing (6), - wherein the one-way clutch (4) is designed to cause a torque transmission from the gear (2) to the output shaft (3) when the gear (2) and the output shaft (3) rotate relative to each other in a blocking direction (42), and to prevent the torque transmission when the gear (2) and the output element (3) rotate relative to each other in a free-running direction (41), and wherein the friction element (5) is designed to generate a predetermined friction torque (45) between the gear (2) and the housing (6).

2. The one-way clutch system according to claim 1, comprising at least one pair of friction elements (5) diametrically opposed with respect to the output shaft (3).

3. A one-way clutch system according to any one of the preceding claims, wherein: The friction element (5) is designed in such a way that the friction torque (45) is generated by means of a radial friction force (45a).

4. A one-way clutch system according to any one of the preceding claims, wherein: The friction element (5) is designed in such a way that the friction torque (45) is generated by means of an axial friction force (45b).

5. A one-way clutch system according to any one of the preceding claims, wherein: The friction element (5) has a friction arm (51) and a friction ring (52) which are in mechanical contact with each other in order to generate the friction torque (45).

6. The one-way clutch system according to claim 5, wherein: The friction arm (51) is fixed to the gear (2), and the friction ring (52) is fixed to the housing (6).

7. The one-way clutch system according to claim 5, wherein: The friction arm (51) is fixed to the housing (6), and the friction ring (52) is fixed to the gear (2).

8. The one-way clutch system according to any one of claims 5 to 7, wherein: The friction arm (51) is designed in the form of a plate.

9. The one-way clutch system according to any one of claims 5 to 8, wherein: The friction arm (51) has a base region (51a) and at least one friction region (51b), wherein the friction region (51b) extends from the base region (51a) in a circumferential direction, and wherein the friction region (51b) has a friction surface (51c) in contact with the friction ring (52).

10. A one-way clutch system according to any one of the preceding claims, wherein: The one-way clutch (4) is constructed as a clamp roller type one-way clutch.

11. A vehicle, in particular an electric bicycle, comprising a one-way clutch system (1) according to any one of the preceding claims.

12. The vehicle according to claim 11, further comprising a drive unit (102) which is connected to the gearwheel (2) in a torque-transmitting manner and a crank gear (104) which is connected to the output shaft (3) in a particularly rotationally fixed manner.

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