Shifting device with freewheel function for a gearbox and gearbox with the shifting device

Abstract

Switching device (1) for a gearbox, with a support body (2), wherein the support body (2) can be arranged on a first component, with a shift sleeve body (4), wherein the shift sleeve body (4) is arranged on the support body (2) so as to be displaceable in an axial direction, with a coupling body (3), wherein the coupling body (3) can be arranged on a second component, wherein the switching device (1) can assume a release state and a switching state as operating states, wherein in the release state the switching sleeve body (4) and the coupling body (3) are disengaged and wherein in the switching state the switching sleeve body (4) is engaged with the coupling body (3), with synchronization means for synchronizing the rotational speeds of the shift sleeve body (4) and the clutch body (3) during the transition from the release state to the switching state, with a freewheel device (19), wherein the freewheel device (19) is designed to enable freewheeling in a first direction of rotation in the switching state and to block it in an opposite direction, characterized in that the freewheel device (19) is formed by a switching toothing (20) on the switching sleeve body (4) and a counter toothing (21) on the coupling body (3).

Description

[0001] The invention relates to a shifting device for a transmission having the features of the preamble of claim 1. Furthermore, the invention relates to a transmission having the shifting device.

[0002] Freewheel devices are used in transmissions. These devices have the properties of transmitting drive torque in a first direction of rotation and freewheeling in a second direction. Such freewheel devices are also used as overrunning clutches. Other components used in transmissions are shifting units, which can engage and decouple two shafts in a rotationally fixed manner. Furthermore, components are known from the prior art that can implement both the freewheel function and the shifting function.

[0003] For example, the publication DE 10 2014 215 418 A1, which arguably represents the closest prior art, discloses a synchronizer carrier assembly for a vehicle transmission with a synchronizer carrier having external teeth. The synchronizer carrier is ring-shaped around an axis of symmetry and is indirectly mounted on a shaft. A freewheel unit is positioned radially between the synchronizer carrier body and the shaft on a freewheel inner ring arranged on the shaft.

[0004] Further synchronous carrier arrangements are known, for example, from DE 1 212 358 B and US 1,752,937 A.

[0005] From DE 2 250 533 A a reversible freewheel clutch is known, which is used there for driving front wheels when their rotational speed falls below that of the rear wheels.

[0006] Further freewheel clutches are known from GB 858 460 A and FR 844 331 A.

[0007] The object of the present invention is to propose a shifting device with a freewheel function for a transmission that offers functional advantages. This object is achieved by a shifting device having the features of claim 1 and by a transmission having the features of claim 10. Preferred or advantageous embodiments of the invention emerge from the subclaims, the following description, and the accompanying figures.

[0008] The subject matter of the invention is a shifting device for a transmission. The transmission is, in particular, a vehicle transmission. The transmission is particularly preferably designed as an automatic transmission, a manual transmission and / or a gear change transmission. The shifting device has the function of coupling and decoupling a first component and a second component in a rotationally fixed manner at least in one direction of rotation. The components can, for example, be designed as a first and a second shaft. Furthermore, the shifting device implements a freewheel function, so that one of the components can always be rotated in one direction of rotation independently of the other component, regardless of the operating state.

[0009] The switching device comprises a support body, wherein the support body is arranged or can be arranged on the first component. In particular, the first component forms part of the switching device. Particularly preferably, the support body is connected to the first component in a rotationally fixed manner.

[0010] The switching device has a shift sleeve body, wherein the shift sleeve body is arranged on the support body so as to be displaceable in an axial direction. The shift sleeve body and the support body preferably have, at least in sections, axial toothing in the circumferential direction, which enables an axial relative displacement between the shift sleeve body and the support body, but forms a positive coupling in the circumferential direction. A main axis of the switching device is defined by the support body and / or the shift sleeve body and / or the components, wherein the terms "axial" and "in the circumferential direction" refer to this main axis. The support body and / or the shift sleeve body and / or the switching device preferably rotate(s) about the main axis during operation.

[0011] The switching device has a clutch body, wherein the clutch body is and / or can be arranged on the second component. Optionally, the second component forms a component of the switching device. The clutch body can be formed in one piece. Alternatively, the clutch body is implemented as a subassembly comprising multiple elements or components.

[0012] The switching device can assume at least a release state and a switching state as operating states. Optionally, the switching device can assume further operating states, for example as intermediate states. In the release state, the shift sleeve body and the clutch body are disengaged. In this operating state, the first and second components can assume different angular velocities. In the switching state, the shift sleeve body is engaged with the clutch body. In particular, the clutch body and the shift sleeve body, and thus the support body and the first component, are positively coupled to one another in a circumferential or rotational direction.

[0013] The shifting device has synchronization means for synchronizing the rotational speeds of the shift sleeve body and the clutch body so that they are synchronized during the transition from the release state to the shift state, in particular, they run at the same rotational speed. The synchronization means can be of any design and based on any mode of operation.

[0014] Optionally, the synchronization means comprises a synchronous running sensor for detecting a synchronous relative rotational movement and / or reversal of the relative rotational movement between the shift sleeve body and the clutch body, which prevents switching into the switching state in the case of asynchronous rotational movement and enables switching into the switching state in the case of synchronous rotational movement or after a reversal of the relative rotational movement.

[0015] The switching device has a freewheel device, wherein the freewheel device is designed, in the switched state, to enable freewheeling, in particular of the clutch body relative to the support body and / or to the first component, in a first direction of rotation in the direction of rotation about the main axis and to lock it in an opposite direction. Preferably, the freewheel device with this property is also designed as an overrunning clutch.

[0016] Within the scope of the invention, it is proposed that the freewheel device be formed by a gear toothing on the shift sleeve body and a counter toothing on the clutch body. Thus, the invention proposes implementing the freewheel function through toothing in the shift sleeve body and the clutch body. In particular, the switching device according to the invention achieves that, due to its design, the synchronization process is implemented and only subsequently is the freewheel device activated. The invention is based on the following considerations: With an activatable or switchable freewheel, such as the one described in the aforementioned publication, the freewheel's locking function can be activated regardless of the current speed difference between the connected components. In simple terms, three different operating points can prevail at the time the freewheel is activated: 1. Largely synchronous operation between the two components to be connected. The effect of the now active freewheel only becomes apparent when the two components attempt to move relative to each other in the freewheel's locking direction, in which a torque is transmitted opposite to the relative direction of movement. 2. Relative movement of the components to be connected counter to the locking direction. The effect of the now active freewheel only becomes apparent when the relative movement direction between the components is reversed. 3. Relative movement of the components to be connected in the locking direction. The now locking freewheel attempts to abruptly stop the relative movement, which can result in very large accelerations and forces.

[0017] In contrast, due to the synchronous running sensor or the synchronization means, the switching device can only be switched or activated during largely synchronous movement of the two components, so that situations 2 and mainly 3 as previously described can be safely avoided.

[0018] The switching device thus forms a switchable positive connection between two components, which in the deactivated state enables free relative movement between the components in both directions; in the active state and when the components move relative to one another in one direction of movement, it has a blocking effect and the positive connection is automatically released in the event of relative movement opposite to the blocking direction; integration of synchronization means, so that activation of the connection is only released when the movement is almost synchronous and is otherwise mechanically blocked or prevented.

[0019] In a preferred design embodiment of the invention, the shift teeth are configured as a sawtooth profile. The sawtooth profile ensures that, upon relative rotation between the clutch body and the shift muffle body, rotation is enabled in the first direction of rotation and blocked in the opposite direction. Preferably, the sawtooth profile has a wall arranged in an axial plane relative to the main axis, and from the base of which extends a sawtooth profile that rises from the wall in the circumferential direction.

[0020] The counter-toothing is preferably designed as a negative or complementary toothing to the switching toothing, so that in the first direction of rotation, the sawtooth profiles can slide off each other, creating a freewheel. In the opposite direction, the walls of the switching toothing and counter-toothing come into contact with each other, creating a positive coupling.

[0021] In principle, the synchronization means can be designed in any desired manner. However, it is preferred that the synchronization means comprise a synchronizer ring with a locking toothed section and with a friction cut. The friction section can in particular be designed as a conical section. In particular, the synchronization means can be designed as a single-cone or a multi-cone synchronization device. In a further development, it is preferred that the clutch body comprise a counter-friction section which can enter into frictional engagement with the friction section. Optionally, additional friction cones are arranged between the friction section and the counter-friction section.

[0022] It is possible for the synchronization work to be performed by the synchronizer ring. Alternatively, the synchronization can be implemented via a control device, which forms part of the switching device, by controlling a motor that drives the switching device. In this embodiment, part or a major part of the synchronization work can be performed by the motor. In this alternative, the synchronizer ring forms a synchronization sensor, which ensures that switching from the release state to the switching state only occurs when the rotational speeds of the components are synchronized with one another.

[0023] In a preferred development of the invention, it is provided that the synchronization means comprises a spring module, wherein the spring module acts between the shift sleeve body and the synchronizer ring and wherein a synchronization force is transmitted from the shift sleeve body to the synchronizer ring via the spring module.

[0024] The spring module preferably spaces the shift sleeve body and the synchronizer ring, in particular the locking contour of the shift sleeve body from the locking contour of the synchronizer ring.

[0025] In a preferred embodiment of the invention, when the switching device is in the release state, the spring module biases the shift sleeve body against movement into the switching state. Alternatively or additionally, when the switching device is in the switching state, the spring module biases the shift sleeve body against movement into the release state. In particular, the spring module is designed to be bistable, so that the spring module is self-retaining in the switching state and self-retaining in the release state. Thus, the states of the switching device are maintained even without the introduction of force by the shift sleeve body.

[0026] In a preferred structural embodiment of the invention, the spring module is designed as a dead-center spring module, wherein the dead center is passed or exceeded during the transition from the release state to the switching state. Similarly, the dead center is passed or exceeded during a transition from the switching state to the release state.

[0027] In a preferred development of the invention, the freewheel device and the spring module are designed such that actuation of the freewheel device leads to a switching of the switching device from the switched state to the release state. When the freewheel device is actuated, the spring sleeve body is displaced in the axial direction by the clutch body against the spring force of the spring module. The displacement path is dimensioned such that the spring module is guided over the dead center and / or switches the bistable states. After the dead center is exceeded, the switching sleeve body is pressed by the spring module into the release state, so that a switching of the switching device occurs. Switching to the switched state is only possible by applying a switching force, e.g. via the switching sleeve body.

[0028] A further object of the invention relates to a transmission with the switching device as described above or according to one of the preceding claims.

[0029] Further features, advantages, and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. These show: Fig. 1 a schematic three-dimensional partially sectioned representation of a switching device as an embodiment of the invention; Fig. 2 the switching device in the Fig. 1 with further components displayed; Fig. 3 the switching device of the previous figures in a switching state; Fig. 4 a three-dimensional representation of the switching device of the preceding figures with graphically displayed synchronization device; Fig. 5 a schematic longitudinal section along the main axis of the switching device of the preceding figures.

[0030] The Fig. Figure 1 shows a schematic three-dimensional, partially sectioned view of a switching device 1 in a release state. The switching device 1 has the function of coupling or decoupling a first and a second shaft (not shown) as components, optionally in a free-running direction, in one rotational direction. Fig. 1, the switching device 1 is in the release state, so that the two shafts or components are decoupled from each other and can run in any direction of rotation, for example at different speeds. Fig. Figure 3 shows the switching device 1 in the switched state, with the two shafts coupled to each other in a free-running manner. With the free-running coupling, the components or shafts can rotate freely relative to each other in one direction of rotation; in the opposite direction, the locking direction, the components or shafts are positively connected to each other. The two shafts or components (not shown) extend coaxially to an indicated main axis H.

[0031] The switching device 1 has a support body 2, which is rotationally fixedly connected to the first shaft. Furthermore, the switching device 1 has a coupling body 3, which is rotationally fixedly connected to the second shaft. Instead of a first and a second shaft, other components can also be coupled to the switching device 1.

[0032] On the support body 2, a shift sleeve body 4 is arranged, which is arranged axially displaceable to the main axis H on the support body 2. In the Fig. In the release state shown in Figure 1, the shift sleeve body 4 is disengaged from the clutch body 3.

[0033] The support body 2 has external teeth 5, which are designed as axial teeth and / or teeth with teeth running in the axial direction. The shift sleeve body 4, in contrast, has internal teeth 7, which engage with the external teeth 6 and enable axial displacement of the shift sleeve body 4 on the support body 2. To initiate the displacement, the shift sleeve body 4 has a circumferential groove 8 for engagement of a shifting element, such as a shift fork. Both the support body 2 and the shift sleeve body 4 are roughly designed as a hollow cylinder and are arranged coaxially and / or concentrically to the main axis H.

[0034] The shifting device has a synchronization device 9, which forms a synchronization means of the shifting device 1. The synchronization device 9 has a synchronizer ring 10, which comprises a locking tooth section 11 and a friction section 12. The locking tooth section 11 is designed to be congruent with the external toothing 6 in terms of the toothing, so that the shift sleeve body 4 with the internal toothing 7 can first be displaced within the external toothing 5 and subsequently penetrate the locking tooth section 11. The synchronizer ring 10 can be pivoted in the circumferential direction about the main axis H, so that, depending on the angular position of the synchronizer ring 10, traversing the locking tooth section 11 with the internal toothing 7 is possible and is locked in other positions.

[0035] The synchronization device 9 has a spring module 13, wherein the spring module 13 is formed by a plurality of individual springs 14. The plurality of individual springs 14 or the spring module 13 is supported on the one hand in a first receiving groove 15, which is arranged on the shift sleeve body 4, and on the other hand on a second receiving groove 16, which is arranged on the synchronizer ring 10, so that the individual springs 14 and / or the spring module 13 act between the shift sleeve body 4 and the synchronizer ring 10. The first receiving groove 15 is arranged in a circumferential web section 17, which simultaneously forms a mechanical stop for the synchronization device 9 or the synchronizer ring 10. The spring module 13 can be designed to hold the synchronizer ring 10 at least at an axial distance d in the axial direction from the internal toothing of the shift sleeve body 4. Alternatively, the distance d can be achieved or ensured by a different design.

[0036] In the Fig. In Figure 2, the switching device is also shown in the released state, but the web section 17 is drawn all the way around, so that the fixation of the individual springs 14 of the spring module 13 is better illustrated. The switching device 1 functions as follows: In the Fig. 1 and Fig. 2, the shift sleeve body 4 is in the end position in the direction of the support body 2. The synchronizer ring 10 is pressed in the direction of the clutch body 3 by the individual springs 14, which are designed as over-center springs, and / or by the spring module 13, this movement being limited by a mechanical travel limiter between the shift sleeve body 4 and the synchronizer ring 10. This mechanical travel limiter is implemented by means of a shoulder on the synchronizer ring 10 and a ring, which is formed by the web section 17, on the shift sleeve body 4 for receiving the individual springs 14. The friction section 12 of the synchronizer ring 10 is arranged without contact with a counter-friction section 8 of the clutch body 3.

[0037] The teeth of the locking toothed section 11 are arranged axially congruent with the teeth of the external toothing 5, so that the locking toothed section 11 and / or the synchronizer ring 10 is / are in a releasing position. For locking, the locking toothed section 11 and / or the synchronizer ring 10 can rotate relative to the support body 2 in the circumferential direction, so that the teeth of the locking toothed section 11 are positioned in front of the grooves of the external toothing 6 of the support body 2 and thereby lock the shift sleeve body 4 during axial movement.

[0038] During a switching operation, the switching device 1 is transferred from the release state to a switching state. In this case, an actuating force is introduced into the shift sleeve body 4, in this case via the groove 8, so that the shift sleeve body 4 is displaced in the axial direction. As a result of the displacement, an axially acting force is introduced onto the synchronizer ring 10 via the spring module 13, so that the synchronizer ring 10 is also displaced axially and initially bears against the counter friction section 18 via the friction section 12 in a sliding frictional contact. The sliding frictional contact synchronizes the rotational speeds between the support body 2 and the clutch body 3 and thus between the first and second shafts or the components.The synchronizer ring 10 is arranged in the axial direction such that it can rotate freely at least over a certain angular range and is sufficiently spaced from the internal toothing 7 so that rotation by the synchronizer ring 10 is initially unhindered. The sliding contact causes the synchronizer ring 10 to pivot about the main axis H, so that it initially moves into a locking position. As soon as the rotational speeds of the supporting body 2 and the clutch body 3 are equalized and a reversal of the relative rotational movement between the shift sleeve body and the clutch body occurs, the synchronizer ring 10 pivots back such that the teeth of the locking toothing section 11 are aligned with the teeth of the external toothing 6.In an alternative embodiment, the synchronizer ring 10 can be unlocked (once the rotational speeds of the support body 2 and the clutch body 3 are equalized) by further advancing the shift sleeve body 4, pivoting it back so that the teeth of the locking toothing section 11 are aligned with the teeth of the external toothing 6. Then, the locking toothing section 11 and the synchronizer ring 10 are in the released position. Upon further axial displacement of the shift sleeve body 4, the internal toothing 7 moves through the locking toothing section 11.

[0039] In the Fig. 3, the switching device 1 is shown in the switching state, wherein the switching sleeve body 4 is opposite the switching state in the Fig. 1 is axially displaced.

[0040] The individual springs 14 of the spring module 13 are designed as dead center springs, which assume a bistable function. While the individual springs 14 of the spring module 13 in the release state of the switching device 1 in the Fig. 1 elastically secure a spacing d between the locking toothing section 11 and the internal toothing 7 of the shift sleeve body 4 (this in conjunction with a mechanical travel limitation between the shift sleeve body 4 and the synchronizer ring 10), the individual springs 14 of the spring module 13 are in the switching state in the Fig. 3 are folded over a dead center, so that they now resiliently secure the switching state. The mechanical travel limitation between the shift sleeve body 4 and the synchronizer ring 10 ensures that, in the open end position of the shift sleeve body 4, the friction section 12 is safely spaced from the counter friction section 18, thus minimizing friction losses in the open state.

[0041] When returning from the switching state to the release state, the dead center and thus a spring force of the spring module 13 must be overcome.

[0042] In the Fig. 4 shows the switching device 1 in a three-dimensional representation, wherein the support body 2 and the clutch body 3 form a freewheel device 19. The freewheel device 19 is formed by a switching toothing 20 of the shift sleeve body 4 and a counter toothing 21 of the clutch body 3. The switching toothing 20 is aligned in the axial direction and is designed to run circumferentially. The counter toothing 21 is similarly aligned in the axial direction and is designed to run circumferentially. The switching toothing 20 and the counter toothing 21 are jointly designed such that it is free-running in one direction of rotation about the main axis H and locked in the opposite direction. This is achieved by sawtooth sections 22a in the switching toothing and by sawtooth sections 22b, each of which has a wall 23a,b and a sawtooth profile 24a,b that adjoin the wall 23a,b.In the locking direction, the wall sections 23 a, b lie against each other in a locking manner in the direction of rotation; in the opposite direction, the sawtooth profiles 24 a, b can slide on each other, so that a freewheel is implemented.

[0043] The Fig. 5 shows the switching device 1 in a schematic longitudinal section along the main axis H. It can be seen that the locking toothing section 11 of the synchronizer ring 10 and the internal toothing 7 of the shift sleeve body 4 are sufficiently spaced apart by the distance d that the synchronizer ring 10 has sufficient time to rotate into the locking position until the internal toothing 7 of the shift sleeve body 4 meets the locking toothing section 11.

[0044] If, in the switching state, the clutch body 3 is rotated relative to the support body 2 and / or the first shaft relative to the second shaft in the freewheeling direction, the sawtooth profiles 24a,b run onto one another, so that an axial distance between the clutch body 3 and the shift sleeve body 4 is increased.

[0045] By increasing the axial distance, the dead center of the spring module 13, in particular of the individual springs 14, is exceeded, causing the spring module 13 or the individual springs 14 to fold over and the switching device 1 to enter the release state. In the release state, the clutch body 3 and the support body 2, or the first and second shafts, can rotate freely and / or independently of one another.

[0046] To reactivate the switching device 1 into the switching state with a blocked direction of rotation, the switching device 1 must be actively actuated again so that the switching sleeve body 4 is again displaced in the axial direction, as previously described.

[0047] Preferably, the synchronizer ring 10 is designed with a friction section 12 and a counter-friction section 18 on the clutch body 3 as a synchronizer sensor (with only low friction torques), which can be dimensioned much more weakly, wherein the synchronization between the first and second shafts or between the support body 2 and the clutch body 3 is achieved by an active speed adjustment of a driving motor. Thus, a large part of the synchronization work is implemented by the motor and not by the synchronizer sensor. The advantage of a synchronizer sensor is the lower friction losses when an attempt is made to move the switching device into the switching state before a synchronous rotational movement is achieved. List of reference symbols 1 switching device 2 supporting bodies 3 coupling bodies 4 shift sleeve bodies 5 External gearing 6 empty 7 Internal gearing 8 grooves 9 Synchronization device 10 Synchronizer ring 11 Locking tooth section 12 Friction section 13 Spring module 14 single springs 15 first receiving groove 16 second receiving groove 17 footbridge section 18 Counter friction section 19 Freewheel device 20 gear teeth 21 Counter-toothing 22 sawtooth sections 23a,b wall sections 24a,b sawtooth profiles H main axis d distance

Claims

[1] Switching device (1) for a gearbox, with a support body (2), wherein the support body (2) can be arranged on a first component, with a shift sleeve body (4), wherein the shift sleeve body (4) is arranged on the support body (2) so as to be displaceable in an axial direction, with a coupling body (3), wherein the coupling body (3) can be arranged on a second component, wherein the switching device (1) can assume a release state and a switching state as operating states, wherein in the release state the switching sleeve body (4) and the coupling body (3) are disengaged and wherein in the switching state the switching sleeve body (4) is engaged with the coupling body (3), with synchronization means for synchronizing the rotational speeds of the shift sleeve body (4) and the clutch body (3) during the transition from the release state to the switching state, with a freewheel device (19), wherein the freewheel device (19) is designed to enable freewheeling in a first direction of rotation in the switching state and to block it in an opposite direction, characterized by that the freewheel device (19) is formed by a switching toothing (20) on the switching sleeve body (4) and a counter toothing (21) on the clutch body (3). [2] Switching device (1) according to claim 1, characterized by that the switching teeth (20) are designed as a sawtooth profile. [3] Switching device (1) according to claim 1 or 2, characterized by that the support body (2) has an external toothing (5) and the shift sleeve body (4) has an internal toothing (7), wherein the external toothing (5) and the internal toothing (7) engage with each other, enable axial displacement and prevent twisting in the direction of rotation. [4] Switching device (1) according to one of the preceding claims, characterized bythat the synchronization means comprises a synchronizer ring (10) with a locking toothed section (11) and with a friction section (12). [5] Switching device (1) according to claim 4, characterized by that the coupling body (3) has a counter friction section (18). [6] Switching device (1) according to claim 4 or 5, characterized by that the synchronization means comprises a spring module (13), wherein the spring module (13) acts between the shift sleeve body (4) and the synchronizer ring (10) and wherein a synchronization force is transmitted from the shift sleeve body (4) via the spring module (13) to the synchronizer ring (10). [7] Switching device (1) according to claim 6, characterized bythat in the release state, the spring module (13) elastically spaces the shift sleeve body (4) against the synchronizer ring (10), so that when the shift sleeve body 4 moves into the switching state, the friction surface section 12 is pressed against the counter-friction section 18 and / or in the switching state, the spring module (13) prestresses the shift sleeve body (4) against movement into the release state. [8] Switching device (1) according to claim 6 or 7, characterized by that the spring module (13) is designed as a dead center spring module and / or the operating states are bistable. [9] Switching device (1) according to one of the preceding claims, characterized by that actuation of the freewheel device (19) leads to switching of the switching device (1) from the switching state to the release state. [10] Gearbox for a vehicle, characterized by a switching device (1) according to one of the preceding claims.

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