Clutch unit for reversibly coupling drive side to output side of drive train

Abstract

The invention relates to a clutch unit for reversibly coupling a drive side (2) to an output side (3) of a drive train, comprising a linearly displaceable shifting collar (8), which sits on a drive element (4) of the drive side (2) and engages with an inner toothing (9) into an outer toothing (5) of the drive element (4), the shifting collar (8) can be displaced along the outer toothing (5) from a discoupled position into a coupled position by likewise engaging the inner toothing (9) into the outer toothing (7) of the output element (6) via the output element (6) of the output side (3), an actuator (10) is provided for displacing the shifting collar (8), which actuator has a linearly displaceable piston (13) and a shifting lever (17), and a shift lever (17) coupled to the piston (13) and connected to the shift collar (8), the piston (13) being axially supported on the shift lever (17) via a spring element (26) when moved into the coupled position.

Description

Technical Field

[0001] The invention relates to a clutch unit for reversibly coupling a drive side and an output side of a drive train. Background Art

[0002] Such a clutch unit, which is also often referred to as a "disconnecting unit", is used, for example, in a drive unit of a motor vehicle, such as a drive axle, which can also be an electric axle, which is often referred to as an e-axle. The clutch unit is used to reversibly connect the drive side to which the torque is applied with the output side to which the torque is to be transmitted and the torque is transferred. For example, the clutch unit can be arranged between the drive unit and the intermediate shaft so as to connect the outlet of the drive unit, i.e. the drive side, with the inlet of the intermediate shaft, i.e. the output side. It is also conceivable to arrange such an intermediate shaft and a differential, whereby the intermediate shaft to which the torque from the drive is applied represents the drive side, and the differential to which the torque is transmitted represents the output side. Therefore, the clutch unit can be incorporated into such a transmission system at different positions. The clutch unit can be switched via a controllable switching device, i.e. an actuator, so as to achieve or cancel the anti-torque coupling of the drive side and the output side.

[0003] Such a clutch unit connects two toothed elements on the drive side and the output side, i.e. an externally toothed drive element, such as a first gear, is arranged on the drive side, and an externally toothed output element, such as a second gear, is arranged on the output side, the two elements being connected in a reversible manner via a coupling element. Such a coupling element is usually provided in the form of a linearly movable shift collar, which is seated on the drive element, i.e. arranged on the drive side and engages with the external teeth of the drive element with the internal teeth. With the aid of an actuator, the shift collar for coupling the drive side with the output side can be moved along the external teeth of the drive element and pushed over the output element, so that the internal teeth of the shift collar also engage with the external teeth of the output element. The drive element and the output element are then coupled together in a rotationally fixed manner via the shift collar, which surrounds both the drive element and the output element and connects the drive element and the output element by tooth engagement.

[0004] When the shift collar is slid from the drive element to the output element, tooth-to-tooth contact can occur between the internal teeth of the shift collar and the external teeth of the output element, that is, if the teeth are not meshing at the moment of engagement, the end faces of the internal teeth of the shift collar will run onto the end faces of the external teeth of the output element. On the one hand, since the actuator continuously applies a sliding force axially to the shift collar, this generates a corresponding load on the entire switching system; on the other hand, the engagement process is delayed until there is a gap between the teeth and the internal teeth are pushed into the external teeth, whereby this sliding process takes place at an actuation speed that is usually controlled by the actuator. Summary of the invention

[0005] The invention is based on the problem of providing an improved clutch unit.

[0006] In order to solve this problem, according to the present invention, a clutch unit for reversibly coupling a drive side and an output side of a transmission system is provided, the clutch unit comprising a linearly movable shift collar, the shift collar being seated on a drive element on the drive side and engaging with an internal tooth in an external tooth of the drive element, and the shift collar can be shifted from a disconnected coupling position to a coupled position along the external tooth via an output element on the drive side by also engaging the internal tooth in the external tooth of the output element, wherein an actuator is provided for shifting the shift collar, the actuator having a linearly movable piston and a shift rod, the shift rod being coupled to the piston and connected to the shift collar, wherein during the movement into the coupled position, the piston is axially supported on the shift rod via a spring element.

[0007] The invention provides for integrating a spring element into the switching path of the actuator, whereby the spring element serves on the one hand as a damping element for relieving the switching system in the event of tooth-to-tooth contact and on the other hand as an energy storage device via which the shift collar can be moved into the coupled position at the highest possible speed.

[0008] The actuator, which is preferably a hydraulic actuator, has a piston which is mounted in a suitable cylindrical housing so that it can be moved linearly. The piston is connected to a shift rod which in turn is connected to a shift collar, which can also be referred to as a sliding collar, for example via a shift fork or the like. If the piston moves axially when the actuator is activated, the shift rod connected to the piston and the shift fork connected to the shift rod move axially, whereby the shift fork then carries the shift collar along with it and pushes the shift collar over the output element, thereby coupling with the output element in the process. According to the invention, a spring element is incorporated in the connection of the piston to the shift rod, via which the piston is axially supported during the movement from the end coupling position to the coupling position. This means that the piston moving from the end coupling position acts axially on the spring element. As long as the shift collar can move freely, i.e. there is no tooth-to-tooth contact and therefore no quasi-axial stop of the shift collar, the shift rod can move freely without compressing the spring element. However, if the shift collar runs against the end face of the external toothing of the output element, i.e. an axial stop occurs, the piston is further displaced axially and at the same time compresses the spring element supported relative to the shift rod, which can no longer be displaced axially. This means that the spring element builds up a restoring force and at the same time the shift rod is pressed against the output element with only a reduced force. As soon as the tooth returns into the gap due to the gear movement, the spring element relaxes, which means that the shift collar is "launched" into the coupling position almost suddenly due to the restoring force. This means that the energy storage device then achieves a sudden and therefore significantly faster coupling of the drive side and the output side.

[0009] The incorporation of a spring element thus has a dual function. On the one hand, it incorporates a defined compliance into the actuation system, since the spring element still achieves damping even in the case of further control and movement of the piston and acts as a quasi-chargeable force accumulator, thereby avoiding the generation of excessive pressures between the shift collar and the output element in the case of the axial stop. On the other hand, the force accumulator acts as an additional actuation means, which enables the shift collar to be moved into the coupling position as quickly as possible, so that the shift collar reaches the coupling position faster than in previously known systems, in which reaching the coupling position depends only on the actuation speed of the actuator, i.e. the speed of the piston movement, when the gear is in play.

[0010] The spring element itself is advantageously a wave spring or a disk spring, whereby a spring element can also be understood as two or more wave springs or disk springs connected in series, i.e. a spring assembly. Such an annular spring enables symmetrical axial support, just as the shift lever can be acted upon symmetrically by the actuating force from the energy storage device.

[0011] The piston itself is arranged on the shift rod so that it can move slightly axially. For this purpose, the piston can move along the shift rod between two axial stops provided on the shift rod. The piston thus has a certain axial play along the shift rod, which allows the piston to move slightly further linearly in order to compress the spring element when the shift collar is in contact with the output element.

[0012] In order to achieve the most compact design possible, the spring element is advantageously supported by one of the axial stops on this side, while on the other side the spring element conveniently supports directly on the piston. This means that the spring element is directly incorporated between such an axial stop and the piston.

[0013] Such an axial stop, preferably both axial stops, can be formed by a retaining ring which is received in a groove on the gearshift rod. The axial stops can be easily formed using such a retaining ring. Preferably, both axial stops are formed by retaining rings, whereby in principle only one axial stop has to be formed in this way, while the other axial stop can also be realized by a shoulder or the like formed on the gearshift rod.

[0014] It is conceivable that, when viewed radially, the spring element rests directly on the retaining ring if the retaining ring is wide enough. Alternatively, it is conceivable to incorporate a support disk which rests on the retaining ring and on which the spring element rests, ie is axially supported.

[0015] In order to make the device as compact as possible, it is advantageous if the piston has an annular recess in which the spring element is received. An annular piston with a central through-hole for the shift rod to pass through comprises a corresponding annular recess which advantageously opens into the through-hole. The annular spring element can now be arranged in this recess so that it is finally integrated into the piston. The piston can be pushed over an axial stop or a retaining ring which can even be adjacent to the piston in the decoupled position, or can be accommodated in the annular recess, depending on the depth of the annular recess or the length of the piston when viewed in the axial direction.

[0016] The actuator itself is preferably an actuator that can be hydraulically controlled, so it can be axially positioned by means of a fluid. Preferably, the piston is activated in two directions via a fluid. This means that in order to move from the disconnected coupling position to the coupled position, the fluid is guided to the cylindrical housing or pressure chamber on one side of the piston until the piston or the shift collar is in the coupled position. In order to move from the coupled position to the disconnected coupling position, the fluid is guided to the other side of the piston or to the pressure chamber of the cylindrical housing there, so that the piston moves back axially and the shift rod and the shift collar are returned by the axial movement of the piston. Therefore, each marking position is actively controlled and approached. In this way, the coupling and disconnection functions can be realized as "normally held" functions. This is because the piston remains in the corresponding position, that is, in the disconnected coupling position or the coupled position, without the need to continuously build up pressure via the actuating hydraulics, which enables more efficient switching operations, such as with regard to the "navigation function" of a motor vehicle, where there is no coupling and no energy consumption is required to maintain this disconnected coupling state.

[0017] In order to realize this actuation function of the actuator in two directions, a first sealing element is advantageously provided to seal the piston toward the gearshift rod, and a second sealing element is provided to seal the piston toward the wall of the tubular member guiding the piston. The two sealing elements define two pressure chambers, one in front of the piston and one behind the piston, and seal the two pressure chambers relative to each other. The piston movement depends on whether the fluid is pressed into the pressure chamber in front of the piston or into the pressure chamber behind the piston. Suitable sealing rings or the like are used as sealing elements.

[0018] The clutch unit according to the invention is advantageously designed as a damping system, which reduces system or component stresses in the case of tooth-to-tooth contact, i.e., in the case of axial contact between the shift collar and the output element. At the same time, better and faster engagement is achieved due to the use of a spring element as an energy or force accumulator, via which the shift collar can be moved very quickly into the engaged position, while also increasing the rigidity of the system.

[0019] Furthermore, the invention relates to a drive train, in particular a drive train of a motor vehicle, comprising a drive element and an output element and a reversibly coupled clutch unit of the type described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be described below based on exemplary embodiments with reference to the accompanying drawings. The accompanying drawings are schematic representations, in which:

[0021] Figure 1 shows a schematic diagram of a clutch unit according to the invention, and

[0022] Figure 2 An enlarged view of a detail of an actuator of a clutch unit with an integrated spring element is shown. DETAILED DESCRIPTION

[0023] Figure 1 A schematic diagram of a clutch unit 1 according to the invention is shown, which can also be referred to as a coupling device and which is used to couple a drive side 2, where a torque is introduced or present, with an output side 3, where the torque is to be transmitted and where the torque is further branched off. A drive element 4 with external teeth 5 is provided on the drive side 2. The drive element 4 is, for example, a gear or an externally toothed shaft.

[0024] On the output side 3, an output element 6 with external teeth 7 is provided, whereby the output element 6 can also be a gear or an externally toothed shaft or the like. The external teeth 5, 7 are linear radial teeth with the same pitch and are located on the same radius. In order to couple the drive element 4 to the output element 6 in a rotationally fixed manner, an axially displaceable shift collar 8 is provided. The shift collar has internal teeth 9, which are located on the Figure 1 In the decoupled position shown, the internal toothing is fully engaged with the external toothing 5 of the drive element 4. This means that in the decoupled position, the shift collar 8 is only coupled to the drive element 4. In this position, no torque can be transmitted to the output element 6. However, if torque transmission is to take place, the shift collar 8 must be axially displaced and pushed onto the output element 6 or the external toothing 7 of the output element, so that the internal toothing 9 of the shift collar 8 is pushed into the external toothing 7 and meshes with the external toothing. At the same time, the internal toothing 9 remains engaged with the external toothing 5, so that the drive element 4 and the output element 6 are coupled in a rotationally fixed manner via the shift collar 8.

[0025] In order to achieve this movement of the shift collar 8, an actuator 10 is provided, which is a hydraulic actuator. The actuator has a housing 11, in which a cylindrical insert 12 made of sheet metal is accommodated, which forms a guide cylinder and in which a piston 13 is arranged. The housing 11 is axially closed by a cover 14. Within the cylindrical insert 12, the piston 13 can be axially displaced via a hydraulic fluid, for which purpose a first pressure chamber 15 is provided, which is realized between the piston 13 and the cover 14. On the opposite side, a second pressure chamber 16 is realized, which is realized between the piston 13 and the end wall of the insert 12. Depending on which pressure chamber 15, 16 the hydraulic fluid is pressed into, the piston will move in one direction or the other.

[0026] Furthermore, a shift rod 17 is provided, which extends through the housing 11 and is sealed relative to the housing via corresponding sealing elements 18, 19. The shift rod 17 is axially displaceable, for which purpose it is coupled to the piston 13. For this purpose, two axial stops 20, 21 are provided on the shift rod 17, which are realized via two retaining rings 24, 25 received in corresponding grooves 22, 23. The piston 13 can be slightly displaced axially between these axial stops 20, 21.

[0027] This axial displacement can be counteracted by a spring element 26 which is designed as a wave spring or a disk spring or a corresponding spring assembly and is accommodated in an annular recess 27 of the piston. On the one hand, the spring element 26 bears on the piston 13 or on the bottom of the recess 17, see Figure 1 , and on the other hand, the spring element bears on the axial stop 20 or the bearing disk 28, which bears on the retaining ring 24. If fluid is pressed into the pressure chamber 15, the piston 13 is displaced to the left until the spring element 26 rests against the bearing disk 28, unless this is already the case.

[0028] The shift rod 17 is also connected to a carrier 29, such as a shift fork, which in turn is connected to the shift collar 8 by a corresponding form-fitting engagement. For this purpose, the shift collar 8, which rotates with the drive element 4, has, for example, a circumferential annular projection 30, which engages in a corresponding receiving groove 31 on the shift fork 29.

[0029] Figure 2 A section of the actuator 10 is shown in an enlarged view. The piston 13 is shown in an enlarged manner, with the pressure chamber 15 on the right and the pressure chamber 16 on the left. In order to also seal towards the piston side, two sealing elements 32, 33 are provided on the piston, via which sealing is provided on the one hand with respect to the shift rod 17 and on the other hand with respect to the cylindrical insert 12.

[0030] Also shown in an enlarged manner is the spring element 26 and the annular recess 27 in which the spring element is retained. Figure 2 As shown, in Figure 1 and Figure 2 In the decoupling position shown, the piston 13 even extends above the stop element 20 and the support disk 28 , which means that the stop element and the support disk are also accommodated in the recess 27 in the decoupling position, thereby providing a very compact design.

[0031] If a torque-proof coupling is to be achieved starting from the decoupled position shown in the figure, in which the drive element 4 is not coupled to the output element 6, hydraulic fluid is pressed into the pressure chamber 15. The piston 13 moves to the left. In this case, the shift rod 17 is driven after the spring element 26 bears on the axial stop 20 and the piston 13 runs against the spring element 26. With the external teeth 5, 7 spaced apart, the shift collar 8 can be easily pushed over the external teeth 7, or the internal teeth 9 can mesh with the external teeth 7. The hydraulic actuation continues until the coupled position is reached, in which the piston 13 moves to a left stop position, for example at the bottom of the cylindrical insert 12.

[0032] However, if the external teeth 5, 7 are not aligned, the internal teeth 9 of the shift collar will inevitably run with their end sides against the end sides of the external teeth 7 of the output element 6, thus producing an axial stop. In this case, after the hydraulic fluid is still pressed into the pressure chamber 15 under pressure, the piston 13 is pushed further axially, wherein the shift rod 17 cannot be further displaced axially due to the effect of the stop. However, the piston 13 can continue to move due to its axial play or its axial mobility; at the same time, the spring element 26 is compressed and a restoring force is built up. The spring element 26 thus acts as a force accumulator. On the one hand, after damping or compliance is incorporated into the actuation system via the spring element 26, this damps the stop movement, so that the component loads in the actuation system are reduced. At the same time, as mentioned above, the spring element 26 acts as an energy storage device. As soon as the movement of the drive element 4 relative to the output element 6 leads to a situation in which the outer teeth 5, 7 are aligned again and the inner teeth 9 can thus be pushed into the outer teeth 7, the spring element 26 suddenly relaxes and launches the shift rod and thus the shift collar 8 in the direction of the output element 6, thus pushing the shift collar 8 over the output element 6 and engaging the teeth 7, 9. Due to the utilization of the energy stored in the spring element 26, this process takes place faster than would be possible via hydraulic actuation of the piston 13 alone if the piston 13 was rigidly connected to the shift rod 17.

[0033] In the coupled position, the piston 13 no longer needs to be pressurized, since the actuator is a double-sided actuator and the device remains in the adopted coupled position due to the use of the corresponding axial toothing. No additional energy consumption is required to maintain this condition. If the coupled position is to be released again, i.e. if the shift collar 8 is to be pushed back again, fluid is pressed into the second pressure chamber 16, so that the piston 13 and, with it, the shift rod 17 together with the shift collar 8 are pushed to the right again and the toothed engagement of the shift collar 8 with the output element 6 is released again.

[0034] Reference numerals list

[0035] 1 Clutch unit

[0036] 2 Drive side

[0037] 3 Output side

[0038] 4. Driving elements

[0039] 5 External teeth

[0040] 6 Output elements

[0041] 7 External teeth

[0042] 8 Shift ring

[0043] 9 internal teeth

[0044] 10 Actuator

[0045] 11 Shell

[0046] 12 Cylindrical insert

[0047] 13 Piston

[0048] 14 Cover

[0049] 15 Pressure Chamber

[0050] 16 Pressure Chamber

[0051] 17 Gear lever

[0052] 18 Sealing element

[0053] 19 Sealing element

[0054] 20 Axial stop

[0055] 21 Axial stop

[0056] 22 grooves

[0057] 23 Grooves

[0058] 24 Retaining ring

[0059] 25 Retaining ring

[0060] 26 Spring element

[0061] 27 Notch

[0062] 28 Support plate

[0063] 29 Bearing

[0064] 30 Annular protrusion

[0065] 31 Shift fork

[0066] 32 Sealing element

[0067] 33 Sealing element

Claims

1. A clutch unit for reversibly coupling a drive side (2) with an output side (3) of a drive train, the clutch unit comprising a linearly movable shift collar (8), the shift collar being seated on a drive element (4) of the drive side (2) and engaging with an internal toothing (9) in an external toothing (5) of the drive element (4), and the shift collar being displaceable from a disconnected position to a coupled position along the external toothing (5) via an output element (6) of the output side (3) by also engaging the internal toothing (9) in an external toothing (7) of the output element (6), wherein: An actuator (10) is provided for displacing the shift collar (8), the actuator having a linearly movable piston (13) and a shift rod (17) which is coupled to the piston (13) and to the shift collar (8), wherein during the movement into the coupled position the piston (13) is axially supported on the shift rod (17) via a spring element (26).

2. The clutch unit according to claim 1, characterized in that: The spring element (26) is a wave spring or a disc spring.

3. The clutch unit according to claim 1 or 2, characterized in that: The piston (13) is movable along the shift rod (17) between two axial stops (20, 21) arranged on the shift rod (17).

4. The clutch unit according to claim 3, characterized in that: The spring element (26) supported on one side on the piston (13) is supported on the other side via one of the axial stops (20).

5. The clutch unit according to claim 3 or 4, characterized in that: At least the axial stop (20), preferably both axial stops (20, 21), supporting the spring element (26) are formed by retaining rings (24, 25) received in grooves (22, 23) on the shift rod (17).

6. The clutch unit according to claim 5, characterized in that A support plate (28) on which the spring element (26) rests rests on the retaining ring (24).

7. The clutch unit according to one of the preceding claims, characterized in that The piston 13) has an annular recess (27) in which the spring element (26) is accommodated.

8. The clutch unit according to one of the preceding claims, characterized in that The actuator (10) is a hydraulically controllable actuator (10).

9. The clutch unit according to claim 8, characterized in that: A first sealing element (32) is provided for sealing the piston (13) toward the shift rod (17), and a second sealing element (33) is provided for sealing the piston (13) toward the wall of a cylinder (12) guiding the piston (13).

10. A drive train, in particular a drive train of a motor vehicle, comprising a drive element (4) and an output element (6) and a clutch unit (1) for reversibly coupling the drive element and the output element according to one of the preceding claims.

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