Release bearing-free central release for a hydraulic or pneumatic clutch actuation device

Abstract

A release bearing-free central release mechanism for a hydraulic or pneumatic clutch actuation device, comprising a cylinder housing (3) which comprises an annular pressure chamber (4) in which an axially movable piston (6) is mounted, which forms an operative connection with a clutch, wherein the cylinder housing (3) is positioned on the one hand on a clutch cover (2) and on the other hand on a transmission cover surrounding a transmission input shaft, characterized in that the central release mechanism (1) is centered either on the clutch cover (2) or the transmission cover.

Description

[0001] The invention relates to a release bearing-free central release mechanism for a hydraulic or pneumatic clutch actuation device, comprising a cylinder housing which comprises an annular pressure chamber in which an axially movable piston is mounted, which forms an operative connection with a clutch, wherein the cylinder housing is positioned on the one hand on a clutch cover and on the other hand on a transmission cover surrounding a transmission input shaft.

[0002] DE 10 2009 010 133 A1 discloses a central release bearing which, as a slave cylinder arranged concentrically around a transmission input shaft, is part of a hydraulic system for clutch actuation. To prevent vibrations from the drive train from being transmitted to the hydraulic system, the housing of the central release bearing is designed in two parts. These partial housings are hydraulically connected to one another but are mechanically decoupled from one another by friction sealing elements, with the friction sealing elements arranged between the housing and the transmission cover. The central release bearing is centered directly on the transmission input shaft. The rotary union, which connects the central release bearing, which rotates with the clutch, and the stationary transmission cover, is designed to be floating, since there is no direct bearing between the transmission cover and the housing of the cover-mounted central release bearing.Due to the mounting of the second sub-housing with the rotary union on the transmission cover and the first sub-housing of the central release bearing on the clutch, axial vibrations of the crankshaft acting on the clutch are transmitted to the friction seals of the rotary union, resulting in increased wear on the friction seals. Furthermore, the tolerance chain is very long when axial vibrations occur. Furthermore, centering the central release bearing on the transmission input shaft requires design modifications to the transmission input shaft during installation.

[0003] The invention is therefore based on the object of specifying a release bearing-free central release mechanism in which measures for the structural adaptation of the transmission input shaft during assembly of the central release mechanism can be dispensed with.

[0004] According to the invention, this problem is solved by centering the central releaser either on the clutch cover or the transmission cover. This has the advantage that centering on the transmission input shaft is eliminated, thus eliminating the need for structural adaptation of the transmission input shaft, which reduces the manufacturing costs of the clutch actuation device. Centering only on one side makes it possible for a rotary union, which connects the rotating central releaser to the stationary transmission cover, to be centered directly on the cylinder housing of the central releaser. This arrangement is applicable to both hydraulic and pneumatic clutch actuation devices.Especially with pneumatic clutch actuation systems, centrifugal force compensation is not required, allowing the seals on the rotary union to be designed to leak when depressurized. With this seal design, no friction torque is generated at the seals, preventing a loss of power from the combustion engine at the central release bearing.

[0005] Advantageously, the cylinder housing rests on a centering device, which is directly connected to an adapter housing connected to the transmission cover. The adapter housing encloses the transmission input shaft. The direct connection between the cylinder housing and the adapter housing reduces the tolerance chain during the transmission of vibrations from the coupling to the transmission. Wear on the rotary union seals is thus eliminated.

[0006] In one embodiment, the cylinder housing is firmly connected to the clutch cover, preferably by screwing, while a motion-absorbing element is arranged between the adapter housing and the transmission cover. Due to the fixed arrangement of the cylinder housing on the clutch cover, additional centering on the transmission input shaft is unnecessary. This simplifies the assembly of the clutch actuation device. The motion-absorbing element, which is arranged between the adapter housing and the transmission cover, absorbs axial vibrations transmitted by the clutch and prevents them from being transmitted to the transmission.

[0007] In one variant, the centering device, preferably consisting of two plain bearings, centers the adapter housing axially and radially on the cylinder housing. The motion-absorbing element compensates not only for vibrations but also for the wobbling movements between the adapter housing and the gearbox cover caused by the coupling.

[0008] In a particular embodiment, the motion-absorbing element is made of an elastic material, preferably an elastomer or silicone. Such materials are cost-effective and yet allow for reliable absorption of the vibrations transmitted from the clutch to the transmission.

[0009] In an alternative, the adapter housing is permanently connected to the transmission cover, while the movement-absorbing element is located between the cylinder housing and the clutch cover. In this case, the central release bearing is centered on the transmission cover. This also eliminates the need for centering on the transmission input shaft, thus reducing the assembly effort for the clutch actuation device.

[0010] Advantageously, the cylinder housing is axially secured to the coupling cover and radially centered on the adapter housing via the centering element. This design allows for minimal radial and axial movement, allowing for good centering of the rotary union and only minimal eccentricity of the axis. The axis offset, which is adjusted via the centering element, is set between the coupling, which is fixed to the motor side, and a central housing attached to the gearbox cover.

[0011] In one embodiment, the centering element is designed as a ball bearing, needle bearing, or plain bearing. These bearings are commercially available components that are inexpensive and therefore contribute to reducing the manufacturing costs of the clutch actuation device.

[0012] In one variant, the motion-absorbing element positioned between the cylinder housing and the clutch cover has radial clearance relative to the cylinder housing. This radial clearance compensates for any axial misalignment of the transmission input shaft.

[0013] In a further development, the motion-absorbing element extending along a recess in the clutch cover has a rounded portion that engages the clutch cover. This rounded portion initiates compensating movements that compensate for the wobbling movement of the clutch. Since the clutch cover is not rigidly connected to the cylinder housing, compensation for these wobbling movements is reliably ensured.

[0014] The invention permits numerous embodiments. Two of them will be explained in more detail with reference to the figures shown in the drawing.

[0015] It shows: Fig. 1: a first embodiment of a central release mechanism according to the invention with a compensation on a gearbox cover, Fig. 2: a second embodiment of the transmission cover according to the invention with a compensation on a clutch cover.

[0016] Identical features are marked with the same reference symbols.

[0017] Fig. 1 shows a first embodiment of a release bearing-free central release mechanism 1 according to the invention, which can be used as a slave cylinder in a hydraulic or pneumatic clutch actuation device. The central release mechanism 1 is firmly fixed to a clutch cover 2. This fixation can be achieved by a positive fit or via an additional component, such as a screw or a rivet. The central release mechanism 1 consists of a cylinder housing 3, which forms an annular pressure chamber 4 on the inside. Due to the annular pressure chamber 4, the cylinder housing 3 has a cavity in which an adapter housing 5 engages, which accommodates a transmission input shaft (not shown).

[0018] A piston 6 is axially movable within the pressure chamber 4 and is sealed from the pressure chamber 4 by piston seals 7. The piston 6 is pressure-connected to the coupling (not shown). Extending along the inner diameter 29 of the cylinder housing 3 are two sleeves 8, 9 made of PTFE (polytetrafluoroethylene), each housing a seal 10, 11 in the form of an O-ring. These PTFE sleeves 8, 9, also referred to as rotary unions, are radially centered on the cylinder housing 3 and axially held by two bayonet rings 12, 13. Both PTFE sleeves 8, 9 run on bushings 14, 15, which are attached to the adapter housing 5 and have very good surface properties. In addition, a centering element 16 is mounted on the inner diameter 29 of the cylinder housing 3, which is designed in the form of two plain bearings 17, 18.The adapter housing 5 and the cylinder housing 3 lie directly on both sides against the plain bearings 17, 18 (. Fig. 1a).

[0019] The adapter housing 5 furthermore has a media supply 19 for a hydraulic or pneumatic medium. At the end of the media supply 19 facing the transmission cover (not shown in detail), a movement absorption element 20 made of an elastic material is attached, which makes contact with the media supply 19 and the transmission cover. Due to the fixed locking of the cylinder housing 3 of the central release mechanism 1 on the clutch cover 2, additional centering of the central release mechanism 1 is unnecessary, since the adapter housing 5 is radially and axially centered on the cylinder housing 3 via the centering unit 16. The compensation of the wobbling movement and axial movements of the clutch is achieved by the movement absorption element 20 arranged between the adapter housing 5 and the transmission cover. This movement absorption element 20 is preferably made of an elastomer or silicone.

[0020] A second embodiment of a release bearing-free central release according to the invention is shown in Fig.2. The adapter housing 5 has a fixing element 21 at the media supply 19, with which the adapter housing 5 is screwed to the transmission cover (not shown). The wobbling movement and the eccentricity of the transmission input shaft axis are compensated for by locking the central release bearing 1 to the clutch cover 2. For this purpose, the cylinder housing 3 has a collar 22 which extends parallel to the clutch cover 2 and rests against it. A second movement-absorbing element 23 is formed between the clutch cover 2 and the collar 22 of the cylinder housing 3.The second movement-absorbing element 23 engages in a recess 24 of the clutch cover 2 in an almost form-fitting manner and has a rounded portion 25 in the direction of the clutch cover 2, which is particularly suitable for executing the wobbling movement of the clutch in the recess 24 without this being transmitted to the central release bearing 1. In addition, a gap 27 is provided between the clutch cover 2 and the outer diameter 26 of the cylinder housing 3, which gap allows radial play between the clutch cover 2 and the cylinder housing 3 to compensate for the axial offset between the clutch fixed to the engine and a central housing fixed to the transmission cover. The cylinder housing 3 is pressed against the clutch cover 2 by a preload spring 28, which engages inside the piston 6 and preloads it against the outer diameter 26 of the cylinder housing 3.The preload spring 28 acts on a disc spring of the clutch (not shown in detail), which presses the entire central releaser 1 onto the clutch cover 2.

[0021] To minimize axial vibrations caused by the crankshaft of the combustion engine on the clutch, the centering between the cylinder housing 3 and the adapter housing 5 must be axially free. This can be achieved using a centering unit designed as a bearing 30, such as a ball bearing, a needle bearing, or a plain bearing.

[0022] Since in this second embodiment, the central release bearing 1 is firmly fixed to the transmission cover and held only axially by the clutch cover 2, the cylinder housing 3 is radially centered on the adapter housing 5, which in turn is firmly attached to the transmission cover. Wobbling movements of the clutch and the offset compensation of the transmission input shaft axis are compensated for at the bracket for the clutch cover 2.

[0023] Both solutions presented have the advantage that the rotary union 8, 9 is centered directly on the cylinder housing 3, resulting in minimal radial and axial movement, thus reducing wear on the friction seals used to seal the central releaser 1. In addition, the central releaser 1 can be mounted on the transmission input shaft without any structural changes.

[0024] The described arrangements can be used in both hydraulic and pneumatic clutch actuation devices. List of reference symbols 1 central release bearing 2 clutch cover 3 cylinder housings 4 Pressure chamber 5 adapter housings 6 pistons 7 Piston seal 8 PTFE cuff 9 PTFE cuff 10 Seal 11 Seal 12 bayonet ring 13 Bayonet ring 14 Cylinder bushing 15 cylinder bushing 16 Centering element 17 plain bearings 18 plain bearings 19 Media supply 20 Motion recording element 21 Fixing element 22 Collar of the cylinder housing 23 Motion recording element 24 recess 25 Rounding 26 Outer diameter of the cylinder housing 27 gap 28 Preload spring 29 Inner diameter of the cylinder housing 30 warehouses

Claims

[1] Release bearing-free central release for a hydraulic or pneumatic clutch actuation device, with a cylinder housing (3) which comprises an annular pressure chamber (4) in which an axially movable piston (6) is mounted, which forms an operative connection with a clutch, wherein the cylinder housing (3) is positioned on the one hand on a clutch cover (2) and on the other hand on a transmission cover surrounding a transmission input shaft, characterized by that the central release bearing (1) is centered either on the clutch cover (2) or the gearbox cover. [2] Central release mechanism according to claim 1, characterized by that the cylinder housing (3) rests on a centering device (16, 30) which bears directly against an adapter housing (5) connected to the gearbox cover, the adapter housing (5) enclosing the gearbox input shaft. [3] Central release mechanism according to claim 1 or 2, characterized bythat the cylinder housing (3) is firmly connected to the clutch cover (2) by screwing, while a movement absorbing element (20) is arranged between the adapter housing (5) and the gear cover. [4] Central release mechanism according to claim 2 or 3, characterized by that the centering device (16), consisting of two plain bearings (17, 18), centers the adapter housing (5) axially and radially on the cylinder housing (3). [5] Central release mechanism according to claim 3, characterized by that the movement absorbing element (20) consists of an elastic material, namely an elastomer or a silicone. [6] Central release mechanism according to claim 1 or 2, characterized by that the adapter housing (5) is firmly connected to the gearbox cover, while the movement absorbing element (23) is formed between the cylinder housing (3) and the clutch cover (2). [7] Central release mechanism according to claim 6, characterized bythat the cylinder housing (3) is held axially on the clutch cover (2) and is radially centered on the adapter housing (5) via the centering element (30). [8] Central release mechanism according to claim 7, characterized by that the centering element (30) is designed as a ball bearing or needle bearing or plain bearing. [9] Central release device according to claim 6, 7 or 8, characterized by that the movement absorbing element (23) positioned between the cylinder housing (3) and the clutch cover (2) has a radial play with respect to the cylinder housing (3). [10] Central release mechanism according to claim 9, characterized by that the movement-absorbing element (23) extending along a recess (24) of the clutch cover (2) has a rounded portion (25) engaging in the clutch cover (2).

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