Anti-rotation means for a central release, and central release with Anti-rotation means

Abstract

The invention relates to an anti-rotation means (1) for a central release (10), having two retaining rings (2), wherein each of the two retaining rings (2) comprises an annular flange part (2a) and a plurality of cylinder wall sections (2b) which project from a first side S1 of the annular flange part (2a) parallel to a centre axis Z of the first annular flange part (2a). Between respective cylinder wall portions (2b) of each retaining ring (2), circumferential spacings (2c) are formed in such a way that in a position in which the cylinder wall portions (2b) of one of the retaining rings (2) engage completely in the respective circumferential spacings (2c) of the other of the retaining rings (2) and the centre axes Z of the two retaining rings (2) coincide, the cylinder wall portions (2b) of the two retaining rings (2) form a circumferentially closed cylinder wall (3). In addition, at least one projection (2c) projects from a second side S2 of the annular flange part (2a) of each of the retaining rings (2).

Description

[0001] Anti-twist device for a central release bearing and central release bearing with anti-twist device

[0002] The invention relates to an anti-twist device for a central release mechanism and a central release mechanism with such an anti-twist device.

[0003] As is well known, central slave cylinders, also known as slave cylinders or CSC for short, are used to engage and disengage a clutch or brake, for example in a vehicle, particularly a motor vehicle. Such a central slave cylinder is therefore part of a hydraulic system for clutch or brake actuation. The key components of a central slave cylinder are a housing in which a piston is accommodated so that it can move axially relative to a central axis of the housing. A pressure chamber is formed between the housing and the piston, which pressure chamber can be filled with a pressurized fluid in order to move the piston in the aforementioned axial direction.

[0004] A common problem is that the piston rotates relative to the housing, which places mechanical stress on the central release mechanism. Various methods for preventing such rotation are known in the art. For example, a cylindrical pin can be pressed into the piston, i.e., connected to it by a force or material fit. The cylindrical pin is guided via a longitudinal groove on the central release mechanism housing. However, this solution requires a structural modification to the piston or housing.

[0005] The object of the invention is to provide an anti-twist device that can be used in a central release mechanism with minimal effort.

[0006] This object is achieved according to the invention by an anti-twist device for a central release mechanism according to claim 1 and a central release mechanism according to claim 7. Preferred embodiments are specified in the subclaims.

[0007] An anti-twist device for a central release mechanism according to embodiments of the invention comprises two retaining rings, each of the two retaining rings comprising an annular flange part and a plurality of cylinder wall sections which protrude from a first side S1 of the annular flange part parallel to a center axis Z of the annular flange part. Circumferential distances are formed between respective cylinder wall sections of each retaining ring such that, in a first position in which the cylinder wall sections of one of the retaining rings fully engage in the respective circumferential distances of the other of the retaining rings and the center axes Z of the two retaining rings coincide, the cylinder wall sections of the two retaining rings form a circumferentially closed cylinder wall, with at least one projection protruding from a second side S2 of the annular flange part of each of the retaining rings.

[0008] The invention therefore proposes an anti-twist device constructed from two retaining rings which, when assembled, are mounted on one another such that the cylinder wall sections of one retaining ring engage in the respective circumferential spacings of the other retaining ring. The two retaining rings are displaceable relative to one another in an axial direction with respect to the center axis Z. This results in particular in the aforementioned first position in which the cylinder wall sections of one retaining ring are inserted completely into corresponding circumferential spacings of the other retaining ring, so that the cylinder wall sections of the two retaining rings form a circumferentially closed cylinder wall. This also results in a second position in which the two retaining rings are so far apart from one another in the axial direction that at least some cylinder wall sections of one retaining ring still engage in corresponding spacings of the other retaining ring.In both positions, the two retaining rings therefore touch each other on at least some of the cylinder wall sections.

[0009] The at least one projection protruding on the first side of each retaining ring serves to engage with a respective element of a central release mechanism, wherein the at least one projection of one of the retaining rings is inserted into a movable piston of the central release mechanism and the at least one projection of the other retaining ring is inserted into a stationary element of the central release mechanism, for example a housing. In this way, when the anti-twist device is used in a central release mechanism, rotation between the piston and housing is prevented. The anti-twist device represents a simple-to-manufacture solution to the problem of said rotation, which can be easily adapted to any type of piston and housing. In particular, the anti-twist device can be made from a plastic material.

[0010] In general, it should be noted that when the terms "in the axial direction" or "in the radial direction" are used within the scope of the invention, these are to be interpreted as referring to the center axis Z of the retaining rings. In particular, when the anti-rotation device is used in a central release mechanism, this center axis Z also represents a corresponding center axis of the central release mechanism.

[0011] Advantageously, the anti-twist device can be designed so that the two retaining rings are identical to each other. Thus, only a single type of retaining ring needs to be produced during manufacture, and when two retaining rings are combined to form an anti-twist device, there is no risk of confusion between the retaining rings.

[0012] In the anti-rotation device according to the invention, the at least one projection can protrude parallel to the center axis Z. This facilitates insertion of the at least one projection into a corresponding recess or cutout of an element of the central release mechanism.

[0013] Preferably, at least one pair of projections is provided, which are spaced apart by an angular distance of less than 30°, in particular less than 15°. Within the scope of the invention, the term "angular distance" is to be interpreted as meaning an angle that the two projections of each pair form with the central axis Z. The angular distance is defined as the smaller of the two angles that the two projections form with the central axis Z.

[0014] According to preferred embodiments, two or more pairs of projections can be present. In the case of an even number of pairs, two pairs are preferably arranged opposite one another. In particular, the respective pairs are arranged at equal angular distances from one another and each enclose the same angular distance from one another. As far as the design of the projections is concerned, the projections of a pair can be semicircular in a plan view perpendicular to the central axis Z, with respective arcuate sections of each pair of projections directed away from one another. In other words, the respective arcuate sections of each pair are directed outwards. This facilitates engagement in an arcuate elongated hole in an element of a central release mechanism, as will become apparent below with reference to the drawing.

[0015] In addition, a circumferential groove can be formed on an outer peripheral side of the annular flange portion. When using the anti-rotation device in a central release mechanism, a bellows or other type of dirt protection can be inserted into this groove, which is axially movable with the piston and a retaining ring or can expand in the axial direction.

[0016] A further embodiment provides for a circumferential receptacle to be formed on the first side S1 of the annular flange part. The circumferential receptacle thus extends in the same axial direction as the cylinder wall sections and preferably radially outside them. It can serve, in particular, to accommodate one end of a spring element, in particular a spring, of the central releaser. The second end of the spring element can then be supported, for example, on the housing of the central releaser. In this way, the spring does not have to be attached directly to the piston of the central releaser.

[0017] The invention also relates to a central release mechanism comprising an annular housing defining a pressure chamber in which a piston is slidably received. An anti-rotation device according to one of the above embodiments is mounted on the piston in such a way that at least one projection of one of the retaining rings of the anti-rotation device engages in a recess of the piston, and at least one projection of the other retaining ring of the anti-rotation device engages in a recess of the housing.

[0018] Due to the engagement of the projections in the piston and the housing, the piston and the housing are secured against relative rotation. When the central release device is in use, as is generally known, the pressure chamber is pressurised with a fluid under vacuum, in particular a hydraulic fluid, so that the piston is displaced in the axial direction with respect to the central axis Z, which during use forms the central axis Z of both the anti-rotation device and the release device as such. In this case, the retaining ring whose projection is received in the recess in the housing remains essentially static on the housing, which means that it does not participate in a release movement of the piston. In contrast, the retaining ring whose projection is received in the recess in the piston moves together with the piston in the axial direction.This means that the retaining rings of the anti-rotation device are moved from the first position to the second. At the same time, the anti-rotation protection between the piston and the housing remains intact.

[0019] In the event that the central release bearing has a spring, this can engage in the circumferential recess of one of the retaining rings.

[0020] The central release mechanism can also have a release bearing, which rests against the piston at an end of the piston remote from the pressure chamber. The recess in the piston, into which the projection of one of the retaining rings of the anti-rotation device engages, is preferably positioned such that it lies radially in the region of a contact surface of the release bearing. In other words, the recess is at the same axial height as the contact surface of the release bearing. This has proven particularly advantageous from a stability perspective.

[0021] The invention is explained in more detail below using a non-limiting embodiment with reference to the drawing.

[0022] The drawing shows:

[0023] Fig. 1 is a perspective view of an anti-twist device according to the

[0024] State of the art;

[0025] Fig. 2a; 2b a perspective view and a longitudinal view of a retaining ring of an anti-twist device according to the invention;

[0026] Fig. 2c, 2d show a perspective view of an anti-rotation device according to the invention in a second position and in a first position, respectively; Fig. 3a to 3c show an embodiment of a central release mechanism according to the invention in various views in the disengaged position;

[0027] Fig. 4a to 4c show an embodiment of a central release mechanism according to the invention in different views in retracted position;

[0028] Fig. 5a shows a positioning plate which can be used in the central release mechanism according to the invention;

[0029] Fig. 5b to 5d various detailed views of the positioning plate in the assembled state;

[0030] Fig. 6a is an exploded view of an assembly of a retaining ring and the positioning plate on the piston of the central release device according to the invention; and

[0031] Fig. 6b is an exploded view of an assembly of another retaining ring on the housing of the central release device according to the invention.

[0032] Figure 1 shows a perspective view of a prior art central release mechanism 10', which is constructed from a housing 11', for example made of aluminum, and a piston 12', for example also made of aluminum, wherein a cylindrical pin 20' is attached to an outer side of the piston 12', which pin is usually made of stainless steel and is guided on the housing 1T.

[0033] Figures 2a and 2b show, in perspective view and in longitudinal view along a central axis Z, a retaining ring 2, which can form part of an anti-rotation device 1 according to the invention (see Figures 2c and 2d). The retaining ring 2 has an annular flange part 2a, from the first side S1 of which several cylinder wall sections 2b protrude, which do not necessarily have to be of the same size, as can be seen in the figures. The cylinder wall sections of Figure 2b protrude essentially perpendicularly from the first side S1 of the flange part 2a, i.e., essentially parallel to the central axis Z.

[0034] Between each two cylinder wall sections 2b, respective circumferential gaps 2c are formed, which also do not need to be of a uniform size. On a second side S2 of the flange part 2a, projections 2d protrude, essentially parallel to the center axis Z. These projections, as shown here, can be arranged in pairs, with two pairs of projections 2d facing each other in this embodiment. The projections 2d are each formed with an arcuate section 2d1, with the arcuate sections 2d1 of each pair pointing away from each other. Furthermore, a circumferential groove 2f is formed on an outer circumferential side 2e of the flange part 2a.

[0035] Figures 2c and 2d show an embodiment of an anti-twist device 1 according to the invention, which is constructed from two identical retaining rings 2, which are shown in Figures 2a and 2b. The retaining rings 2 are brought together such that their respective cylinder wall sections 2b are directed towards one another. As can be seen, in a first position of the retaining rings 2, which is shown in Figure 2d, the cylinder wall sections 2b of each retaining ring 2 engage one another such that a closed cylindrical surface is formed. In a second position of the retaining rings 2, they are shifted relative to one another in the axial direction such that only the respective ends of the cylinder wall sections 2b of the opposite retaining rings 2 touch.

[0036] Figure 3a shows a perspective view of an embodiment of a central release mechanism 10 according to the invention. The central release mechanism 10 comprises a housing 11 that defines a pressure chamber 16 in which a piston 12 can slide axially relative to the center axis Z. A release bearing 13 is mounted on one end of the piston 12 and serves to disengage a clutch or a brake (not shown in the figure). Furthermore, a spring 14 is provided that preloads the piston 12 in the axial direction. As can also be seen, two retaining rings 2 are placed between the housing and the piston 12, forming an anti-twist device 1 shown in Figures 2c and 2d. The central release mechanism 10 is shown in a maximally extended state, in which the piston 12 is fully pushed out. Figure 3b shows a longitudinal section of a section of the central release mechanism 10 shown in Figure 3a.The projection 2d on the first side S1 (see Figure 2a) of one of the retaining rings 2 can be seen, which is inserted into a recess 12a of the piston 12. The recess 12a is located, as can be seen, in the radial direction in the region of a support surface 13a of the axial bearing 13 in the piston 12. In addition, a part of the spring 14 is inserted into a circumferential receptacle 2g. Furthermore, one end of the bellows 15 is inserted from the radial outside into the circumferential groove 2f of the retaining ring 2, so that the bellows 15 unfolds when the piston 12 moves (in the extended position or position of maximum extension shown here).

[0037] Figure 3c shows a section of a side of the central release mechanism 10 of Figure 3a opposite the section in Figure 3b, in longitudinal section. The other of the two identical retaining rings 2 is shown here, with a portion of the spring 14 being inserted into the circumferential receptacle 2g of the retaining ring 2, specifically the opposite portion with respect to the image in Figure 3b, and with one end of the bellows 15 being inserted radially from the outside into the circumferential groove 2f of the retaining ring 2, specifically the opposite end with respect to the illustration in Figure 3b. Furthermore, the projection 2d of the retaining ring 2 is inserted into a recess 11a provided for this purpose in the housing 11.

[0038] Figures 4a to 4c are representations of the central release mechanism 10 corresponding to those in Figures 3a to 3c, but with the central release mechanism 10 shown in the retracted position (minimal extension position). As can be seen in Figures 4b and 4c, the spring 14 is compressed in this position and the bellows 15 is tightly folded.

[0039] With reference now to Figure 5a, a further element is described that can optionally be used in the release device 10 (see Figures 3a, 4a). This is a positioning plate 17, which serves to detect the position of the piston (see Figures 3a, 4b). The positioning plate 17 comprises extensions 17a, which, as shown here, can be arranged in pairs. Figure 5b shows a longitudinal section of the positioning plate 17 in a clamped position between the piston 12 and the contact surface 13a of the release bearing 13. Furthermore, a sensor 18 can be seen, which, together with the positioning plate 17, carries out a wear measurement.

[0040] Figure 5c shows the positioning plate 17 applied to the retaining ring 2 without a release bearing. It can be seen how the extensions 17a are positioned laterally next to the projections 2d of the retaining ring 2. Preferably, the two extensions 17a of a pair have the same angular distance from each other as the projections 2d of each retaining ring 2.

[0041] Figure 5d shows one of the extensions 17a of the positioning plate 17 (transparent line), which is secured against rotation between the recess 12a in the piston 12 and the projection 2d on the retaining ring 2. In general, as shown here, the recess 12a can be designed as a continuous elongated hole.

[0042] Figure 6a is an exploded view showing how the retaining ring 2 and the positioning plate 17 are attached to the piston 12. For this purpose, the projections 2d of the retaining ring 2 and the extensions 17a of the positioning plate 17 are inserted from opposite sides into the recess 12a, which is formed as an arcuate elongated hole, of the piston 12 and clamped there.

[0043] Figure 6b is an exploded view showing how the retaining ring 2 is attached to the housing 11. The projections 2d of the retaining ring are inserted into the recess 11a of the housing 11 in the direction of the thick arrows. It should be noted that Figure 6a shows one of the two retaining rings 2 of an anti-rotation device 1 according to the invention (see Figures 2c and 2e), and Figure 6b shows the other of the two retaining rings 2, both retaining rings 2 being identical.

[0044] 1 Anti-rotation device 2 Retaining ring 2a Flange part 2b Cylinder wall section 2c Circumferential distance 2d Projection

[0045] 2d1 curved section 2e outer peripheral side 2f circumferential groove 2g around running mount

[0046] 10 Central release bearing 11 Housing 11 a Recess 12 Piston 12a Recess 13 Release bearing

[0047] 13a Support surface

[0048] 14 Spring 15 Bellows 16 Pressure chamber 17 Position plate 17a Extension 18 Sensor

[0049] Z center axis 10' central release lever state of the art 11' housing state of the art 12' piston state of the art 20' cylindrical pin state of the art

Claims

Patent claims 1. Anti-rotation device (1) for a central release (10), comprising two retaining rings (2), each of the two retaining rings (2) comprising an annular flange part (2a) and a plurality of cylinder wall sections (2b) which protrude from a first side S1 of the annular flange part (2a) parallel to a center axis Z of the first annular flange part (2a), wherein circumferential distances (2c) are formed between respective cylinder wall sections (2b) of each retaining ring (2) such that, in a position in which the cylinder wall sections (2b) of one of the retaining rings (2) completely engage in the respective circumferential distances (2c) of the other of the retaining rings (2) and the center axes Z of the two retaining rings (2) coincide, the cylinder wall sections (2b) of the two retaining rings (2) form a circumferentially closed cylinder wall (3),and wherein at least one projection (2d) of each of the retaining rings protrudes from a second side S2 of the annular flange part (2a).

2. Anti-rotation device (1) according to claim 1, characterized in that the two retaining rings (2) are identical to one another.

3. Anti-rotation device (1) according to claim 1 or 2, characterized in that the at least one projection (2d) projects parallel to the center axis Z.

4. Anti-rotation device (1) according to one of the preceding claims, characterized in that at least one pair of projections (2d) are present which are spaced apart from one another by an angular distance of less than 15°.

5. Anti-rotation device (1) according to claim 4, characterized in that two or more pairs of projections (2d) are present.

6. Anti-rotation device (1) according to claim 4 or 5, characterized in that the projections (2d) of a pair in a plan view perpendicular to the center rumsachse Z is semicircular, wherein respective arc sections (2d1) of each pair of projections (2d) are directed away from each other.

7. Anti-rotation device (1) according to one of the preceding claims, characterized in that a circumferential groove (2f) is formed on an outer peripheral side (2e) of the annular flange part (2a).

8. Anti-rotation device (1) according to one of the preceding claims, characterized in that a circumferential receptacle (2g) is formed on the first side S1 of the annular flange part (2a).

9. Central release device (10), comprising an annular housing (11) which delimits a pressure chamber (16) in which a piston (12) is slidably received, characterized in that an anti-twist device (1) according to one of the preceding claims is mounted on the piston (12) in such a way that the at least one projection (2c) of one of the retaining rings (2) of the anti-twist device (1) engages in a recess (12a) of the piston (12) and the at least one projection (2c) of the other retaining ring (2) of the anti-twist device engages in a recess (11a) of the housing (11).

10. Central release mechanism (10) according to claims 8 and 9, characterized in that the central release mechanism (10) has a spring (14) which engages in the circumferential receptacle (2f) of one of the retaining rings (2).

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