slave cylinder

Abstract

Slave cylinder (1) with a housing (3) having an annular groove (8) in which an annular piston (12) is guided to be movable back and forth between a retracted (Figure 6) and an extended (Figure 5) position, and with an actuating bearing (16) which is attached to one end of the annular piston (12), wherein the annular piston (12) has at least one stop projection (33, 43) at its actuating bearing-side end, which projects radially inwards from the actuating bearing-side end of the annular piston (12), characterized in that the stop projection (33, 43) is formed on a first snap hook (31, 41) which is integrally connected with the annular piston (12).

Description

[0001] The invention relates to a slave cylinder with a housing having an annular groove in which an annular piston is guided to be movable back and forth between a retracted and an extended position, and with an actuating bearing which is attached to one end of the annular piston.

[0002] European patent EP 1 088 175 B1 discloses a pressure-mediated release system for a vehicle's shift-disconnect clutch, comprising: a piston-cylinder unit, designated as a slave cylinder, arranged concentrically to a drive shaft, the cylinder of which is detachably attached to a transmission housing; an annular piston guided in a pressure chamber radially bounded by a wall of the cylinder bore and a cylindrical surface of a guide sleeve; a release bearing attached to the end of the guide sleeve facing away from the pressure chamber and operatively connected to release elements of the shift-disconnect clutch; the guide sleeve is positioned and sealed on the cylinder; the guide sleeve is radially centered and axially supported on the cylinder; a seal is arranged between the guide sleeve and the cylinder,that their position lies within or partially radially inwardly offset from a projection of the annular surface of the pressure chamber, wherein the cylinder has a projection that engages in an annular space formed in the guide sleeve, wherein a seal is provided between the projection and a wall bounding the annular space, and the guide sleeve is centered on the projection. From German patent application DE 10 2011 081 298 A1, a slave cylinder (CSC) with a substantially concentric slave cylinder housing having a longitudinal axis is known, which has an annular space to form an annular pressure chamber in which an annular piston, which is provided with a seal on the pressure chamber side, is guided axially displaceably, wherein the annular piston acts on a release bearing, and at least one elastic and / or spring element is arranged on the slave cylinder housing in the direction of the release bearing.which provides a tolerance compensation for a stop of the slave cylinder housing for the release bearing in a rear end position of the ring piston.

[0003] A slave cylinder according to the preamble of claim 1 is disclosed in DE 10 2012 207 876 A1. Further prior art is shown in DE 10 2012 201 674 A1.

[0004] The object of the invention is to create a slave cylinder with a housing having an annular groove in which an annular piston is guided to be movable back and forth between a retracted and an extended position, and with an actuating bearing attached to one end of the annular piston, which is inexpensive to manufacture and easy to assemble.

[0005] The problem is solved in a slave cylinder with a housing that has an annular groove in which an annular piston is guided so as to be movable back and forth between a retracted and an extended position, and with an actuating bearing attached to one end of the annular piston, by the fact that the annular piston has at least one stop projection at its actuating bearing-side end, which projects radially inwards from the actuating bearing-side end of the annular piston. The slave cylinder has a longitudinal axis along or parallel to which the annular piston is movable back and forth in the axial direction. The term "axial" refers to the longitudinal axis of the slave cylinder. "Axial" means in the direction of or parallel to the longitudinal axis of the slave cylinder. Similarly, "radial" means transverse to the longitudinal axis of the slave cylinder.The slave cylinder is preferably a concentric slave cylinder with a central through-hole for a shaft, for example, a transmission shaft. Such a concentric slave cylinder is also referred to as a CSC, where the capital letters CSC stand for the English terms Concentric Slave Cylinder. The annular piston defines a hydraulic chamber within the annular groove of the slave cylinder. The stop projection serves to limit the axial travel of the annular piston during operation of the slave cylinder. Depending on the design, the stop projection can be circumferential. However, it is particularly preferable for the annular piston to have several stop projections at its actuating bearing end. The stop projections also advantageously serve to guide the annular piston during operation of the slave cylinder.

[0006] A preferred embodiment of the slave cylinder is characterized in that the stop projection is guided in a guide recess in the housing. The guide recess is advantageously designed as a longitudinal groove. The longitudinal groove preferably extends in the axial direction. The guide recess is advantageously designed to be deep enough that, during operation of the slave cylinder, there is little or no friction between the stop projection(s) and the housing of the slave cylinder. In the embodiment with multiple stop projections, each stop projection is advantageously assigned a guide recess. The guide recesses also advantageously serve to prevent unwanted rotation of the annular piston in the annular groove.

[0007] Another preferred embodiment of the slave cylinder is characterized in that the guide recess has an axial end stop for the stop projection at its end facing away from the annular groove. This prevents the annular piston from moving out of the annular groove or detaching from the slave cylinder in an undesirable manner after its assembly.

[0008] According to the invention, the stop projection is formed on a first snap hook, which is integrally connected to the annular piston. The snap hook allows movement of the stop projection in the radial direction. This enables the snap hook to override the axial end stop on the housing during assembly. Preferably, the snap hook has no preload before assembly and also in the assembled position. This reliably prevents unwanted breakage of the snap hook. During assembly, when the stop projection overrides the axial end stop on the housing, the snap hook moves only so little that unwanted breakage of the snap hook is reliably prevented.

[0009] Another preferred embodiment of the slave cylinder is characterized in that the actuating bearing engages the stop projection. After the annular piston is mounted, the actuating bearing is mounted on the annular piston such that the actuating bearing, in particular a retaining ring of the actuating bearing, engages the stop projection, preferably several stop projections, which are formed on the snap hook. This reliably prevents unwanted overtravel of the axial end stop(s) after assembly. The extended position of the annular piston is defined by the axial end stop(s).

[0010] Another preferred embodiment of the slave cylinder is characterized in that the annular piston has at least one retaining projection at its actuating bearing-side end, which projects radially outwards from the actuating bearing-side end of the annular piston and bears against the actuating bearing in the axial direction. The actuating bearing is advantageously preloaded against the retaining projection by a housing-side supported preload spring. The retaining projection can theoretically be circumferential. In practice, however, several retaining projections are provided at the actuating bearing-side end of the annular piston. During assembly of the actuating bearing, the retaining projection(s) are advantageously overcome by the actuating bearing-side end of the annular piston.

[0011] Another preferred embodiment of the slave cylinder is characterized in that the retaining projection is formed on a second snap hook, which is integrally connected to the annular piston. This allows the actuating bearing to easily jump over the retaining projection during assembly. When the retaining projection jumps over, the snap hook moves radially inwards with the retaining projection. The retaining projection preferably interacts with a retaining ring of the actuating bearing. The retaining ring of the actuating bearing is preferably a bent sheet metal part made of steel.

[0012] Another preferred embodiment of the slave cylinder is characterized in that the annular piston for the actuating bearing has at least one axial contact surface which is spaced axially from the retaining projection to such an extent that a gap is created between the contact surface and the actuating bearing for vibration decoupling of the actuating bearing. This prevents vibrations, such as those caused by pressure fluctuations in the hydraulic system, from being transmitted from the annular piston to the actuating bearing during operation of the slave cylinder.

[0013] Another preferred embodiment of the slave cylinder is characterized in that the annular piston has at least two first snap hooks and at least two second snap hooks, which are arranged evenly distributed in the circumferential direction. Each of the first snap hooks has a stop projection. Each of the second snap hooks has a retaining projection. The first snap hooks are advantageously arranged diametrically. The second snap hooks are also advantageously arranged diametrically. The diametrical arrangement of the snap hooks simplifies the assembly of the annular piston and the actuating bearing. Furthermore, the diametrical arrangement of the snap hooks ensures stable guidance of the annular piston in the annular groove.

[0014] The invention further relates to a ring piston, a housing, and / or an actuating bearing for a slave cylinder described above. These parts are available separately. The ring piston is advantageously manufactured as an injection-molded part.

[0015] The invention may also relate to a method for mounting a slave cylinder as previously described. According to one embodiment of the method, the annular piston is first mounted, wherein the stop projection(s) on the first snap hook override the axial end stop(s) on the housing. After the annular piston has been mounted, the actuating bearing is mounted on the annular piston, wherein the retaining projection(s) on the second snap hook are overridden by the actuating bearing.

[0016] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are described in detail with reference to the drawing. The drawing shows: Fig. 1 a slave cylinder with a ring piston in half-section; Fig. 2 a perspective view of the ring piston made of Fig. 1; Fig. 3 a perspective view of a half section during the assembly of the ring piston into a housing of the slave cylinder made of Fig. 1; Fig. 4 the same representation as in Fig. 3 during the assembly of the actuating bearing on the mounted ring piston; Fig. 5 the slave cylinder out Fig. 1 with the ring piston in its extended position; Fig. 6 the same representation as in Fig. 5 with the ring piston in its retracted position; Fig. 7 an enlarged perspective view of a guide recess in the housing of the slave cylinder; Fig. 8 a sectional view of Fig. 7; and Fig. 9 an enlarged section of the ring piston Fig. 2.

[0017] In the Fig. Figures 1 to 9 show a slave cylinder 1 in various views and sections. The slave cylinder 1 serves in a (not shown) fluidic clutch actuation system to actuate, in particular disengage, a clutch (also not shown).

[0018] The slave cylinder 1 comprises a housing 3 with an inner cylinder 4 and an outer cylinder 5. The inner cylinder 4 radially defines a central through-hole, which serves, for example, for the axial passage of a transmission shaft.

[0019] The term axial refers to a longitudinal axis 7 of the slave cylinder 1. Axial means in the direction of or parallel to the longitudinal axis 7 of the slave cylinder 1. The term radial means transverse to the longitudinal axis 7 of the slave cylinder 1. The inner cylinder 4 and the outer cylinder 5 of the slave cylinder 1 are arranged coaxially to the longitudinal axis 7.

[0020] An annular space 8, also referred to as an annular groove, is formed between the inner cylinder 4 and the outer cylinder 5. The annular groove 8, or annular space 8, represents a hydraulic pressure chamber which is bounded in the slave cylinder 1 by an annular piston 12.

[0021] The ring piston 12 is in Fig. 5 shown in its extended position. In Fig. Figure 6 shows the annular piston in its retracted position. Between its retracted and extended positions, the annular piston 12 is guided so that it can move back and forth in the annular space 8 or in the annular groove 8.

[0022] The ring piston 12 is attached to its housing to seal the hydraulic pressure chamber. Fig. 1 lower end equipped with a U-ring seal 14. The U-ring seal 14 seals the hydraulic pressure chamber in the annular space 8 in a pressure-tight manner. At a Fig. At the upper end of the ring piston 12, an actuating bearing 16 is attached. The actuating bearing 16 is designed as a rolling bearing and is also referred to as a release bearing.

[0023] The actuating bearing 16 comprises an inner bearing ring 18 and an outer bearing ring 19. Rolling elements 20 are arranged in a cage 21 between the inner bearing ring 18 and the outer bearing ring 19. The rolling elements 20 are, for example, balls.

[0024] The actuating bearing 16 further comprises a retaining ring 17. The retaining ring 17 is designed as a bent steel component. The retaining ring 17 is arranged radially inside the actuating bearing 16 and partially surrounds the inner bearing ring 18.

[0025] A preload spring 24 is in the axial direction, in Fig. 1 from below, preloaded against the actuating bearing 16. A collar of a dirt guard 30 is axially positioned between a in Fig. The upper end coil of the preload spring 24 and the inner bearing ring 18 of the actuating bearing 16 are clamped together. The dirt protection device 30 prevents unwanted ingress of dirt into the slave cylinder 1.

[0026] In Fig. Figure 2 shows that the ring piston 12 has first snap hooks 31, 41 at one end facing away from the O-ring seal 14. At the free ends of the first snap hooks 31, 41, a stop projection 33, 43 is formed, which projects radially inwards.

[0027] Furthermore, second snap hooks 32, 42 are formed at the end of the ring piston 12 facing away from the O-ring seal 14. Retaining projections 34, 44 are formed at the free ends of the second snap hooks 32, 42. The retaining projections 34, 44 are directed radially outwards.

[0028] The first snap hooks 31 and 41 are arranged diametrically. The second snap hooks 32 and 42 are also arranged diametrically. The snap hooks 31, 32 and 41, 42 are integrally connected to a base body 36 of the annular piston 12 and extend in the axial direction. The base body 36 of the annular piston 12 essentially has the shape of a straight circular cylinder shell.

[0029] In Fig. 2 further shows that on the base body 36 of the ring piston 12 there are two axial contact surfaces 35, 45 for the actuating bearing (16 in Fig. 1) are formed. The axial contact surfaces 35, 45 are arranged in the area of ​​the second snap hooks 32, 42.

[0030] In Fig. Figure 3 is indicated by an arrow 38, showing that the ring piston 12 is installed first when assembling the slave cylinder 1. The ring piston 12 is then inserted into Fig. 3 moved downwards with the groove seal 14 into the ring groove 8.

[0031] In Fig. 4 is indicated by an arrow 39, that after the assembly of the ring piston 12 the actuating bearing 16 is attached to the assembled ring piston 12.

[0032] In Fig. 5 is indicated by an arrow 50, showing how the ring piston 12 together with the actuating bearing 16 is removed from its in Fig. 5 shown extended position in its Fig. The retracted position shown in section 6 is moved. The path of the ring piston 12 in Fig. The upward movement 5 is limited by the stop projection 33, which projects radially inwards on the first snap hook 31.

[0033] In Fig. Figure 7 shows that in the housing 3, on the outside of the inner cylinder 4, a guide recess 51 is provided for the first snap hook 31 with the stop projection 33. The guide recess 51 forms a guide track for the first snap hook 31 with the stop projection 33.

[0034] The housing-side guide track 51 is limited at the release bearing-side end of the inner cylinder 4 of the housing 3 by an axial end stop 53 for the stop projection 33. During the assembly of the ring piston 12 (see Fig. 3) the axial end stop 53 is skipped by the stop projection 33 on the first snap hook 31.

[0035] However, skipping only occurs in the compression direction of the annular piston 12. In the opposite expansion direction of the annular piston 12, that is, during operation of the clutch system, when the annular piston 12 reaches its in Fig. When the extended state shown in 5 is reached, the first snap hook 31 strikes the axial end stop 53 with the stop projection 33.

[0036] In Fig. Figure 8, indicated by arrows 58 and 59, shows that the guide track or guide recess 51 includes a depression 55. The depression 55 serves to prevent or reduce unwanted friction between the stop projection 33 and the guide track or guide recess 51.

[0037] In Fig. Figure 9 shows that the retaining projection 34 for the actuating bearing 16 is axially spaced from the axial contact surface 35. In a summary view of the Fig. 9 with Fig.Figure 1 shows that in the axial direction, at the axial distance between the retaining projection 34 and the axial contact surface 35, there is a gap indicated by arrows 47 and 48. The gap 47, 48 serves to decouple vibrations during operation of the slave cylinder 1. Reference symbol list 1 slave cylinder 3 cases 4 internal cylinders 5 external cylinders 7 Longitudinal axis 8 ring groove 12 ring pistons 14 U-ring seal 16 actuating bearings 17 retaining ring 18 inner bearing ring 19 Outer bearing ring 20 rolling elements 21 cage 30 Dirt protection device 31 first snap hook 32 second snap hook 33 Stop lead 34 Holding advantage 35 axial contact surface 36 basic shapes 38 Arrow 39 Arrow 41 first snap hook 42 second snap hook 43 lead 44 Holding advantage 45° axial contact surface 47 Arrow 48 Arrow 50 arrows 51 Guide recess 53 axial end stop 55 In-depth study 58 Arrow 59 Arrow

Claims

[1] Slave cylinder (1) with a housing (3) which has an annular groove (8) in which an annular piston (12) is arranged between a retracted ( Fig. 6) and an extended ( Fig. 5) position is guided back and forth, and with an actuating bearing (16) which is attached to one end of the annular piston (12), wherein the annular piston (12) has at its actuating bearing-side end at least one stop projection (33, 43) which projects radially inwards from the actuating bearing-side end of the annular piston (12), , characterized by that the stop projection (33,43) is formed on a first snap hook (31,41) which is integrally connected to the annular piston (12). [2] Slave cylinder according to claim 1, characterized by that the stop projection (33,43) is guided in a guide recess (51) of the housing (3). [3] Slave cylinder according to claim 2, characterized bythat the guide recess (51) has an axial end stop (53) for the stop projection (33,43) at its end facing away from the annular groove (8). [4] Slave cylinder according to one of the preceding claims, characterized by that the actuating bearing (16) engages around the stop projection (33,43). [5] Slave cylinder according to one of the preceding claims, characterized by that the annular piston (12) has at least one retaining projection (34, 44) at its actuating bearing-side end, which projects radially outwards from the actuating bearing-side end of the annular piston (12) and bears against the actuating bearing (16) in the axial direction. [6] Slave cylinder according to claim 5, characterized by that the retaining projection (34,44) is formed on a second snap hook (32,42) which is integrally connected to the annular piston (12). [7] Slave cylinder according to claim 5 or 6, characterized bythat the annular piston (12) for the actuating bearing (16) has at least one axial contact surface (35, 45) which is spaced apart in the axial direction from the retaining projection (34, 44) to such an extent that a gap (47, 48) for vibration decoupling of the actuating bearing (16) is formed between the contact surface (35, 45) and the actuating bearing (16). [8] Slave cylinder according to one of the preceding claims, characterized by that the annular piston (12) has at least two first snap hooks (31, 41) and at least two second snap hooks (32, 42) which are arranged uniformly distributed in the circumferential direction. [9] Annular piston (12), housing (3) and / or actuating bearing (16) for a slave cylinder (1) according to one of the preceding claims.

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