CN110067818B

CN110067818B - Auxiliary cylinder with multiple single pistons, operating device and clutch system

Info

Publication number: CN110067818B
Application number: CN201910048065.6A
Authority: CN
Inventors: 西蒙·奥特曼; 安德烈亚斯·达根巴赫; 欧尔夫·沃纳; 菲利普·瓦格纳; 奥雷利昂·高尔斯
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2018-01-23
Filing date: 2019-01-18
Publication date: 2022-09-13
Anticipated expiration: 2039-01-18
Also published as: CN110067818A; DE102018101409B3

Abstract

The invention relates to a slave cylinder (1) for a clutch actuating device of a motor vehicle, having a housing (2), a piston unit (3) which has a plurality of single pistons (4a, 4b, 4c) accommodated in the housing (2) and which acts in an adjusting manner on an actuating bearing (5) during operation, and having a carrier element (6) which couples the single pistons (4a, 4b, 4c) to the actuating bearing (5), each single piston (4a, 4b, 4c) being supported in a fixed manner on a mating contact region (8a, 8b, 8c) on the carrier element (6) by means of a contact region (7a, 7b, 7c), wherein the two single pistons (4b, 4c) are supported with their contact regions (7b, 7c) at least in the radial direction relative to the mating contact region (8b) of the carrier element (6), 8c) can be arranged in a relatively movable manner. The invention also relates to an actuating device having the auxiliary cylinder (1) and to a clutch system.

Description

Auxiliary cylinder with multiple single pistons, operating device and clutch system

Technical Field

The invention relates to a secondary cylinder for a clutch actuating device of a motor vehicle, such as a PKW, LKW, bus or other commercial vehicle, comprising: a housing; a piston unit having a plurality of individual pistons accommodated in a housing and acting in an adjusting manner on the actuating bearing during operation; and a carrier element coupling the single pistons to the actuating bearing, wherein each single piston is supported on a mating contact region on the carrier element in a manner that it is fixed against displacement by means of the contact region. The slave cylinder with three single pistons is thus realized as a multi-piston separator with different single pistons. The invention also relates to an actuating device for a clutch of a motor vehicle, comprising the secondary cylinder; and to a clutch system for a drive train of a motor vehicle, which has such an actuating device.

Background

Such auxiliary cylinders and clutch actuation systems are well known from the prior art. DE 102012212310 a1 discloses a release system for actuating a clutch, wherein the release system is designed in the form of a Concentric Slave Cylinder (CSC/"Concentric Slave Cylinder"). Two different pistons are used here for actuating one clutch each. Furthermore, prior art is known to the applicant, which has not yet been disclosed, in which one of the two known annular pistons is replaced by its own piston unit having a plurality of separate single pistons.

However, in the embodiments known from the prior art, it has proven to be a disadvantage: in order to be loaded with a certain preload during the corresponding centering operation, these embodiments are of relatively complex design and are therefore relatively complicated to produce. For this purpose, rail arrangements have hitherto been selected, for example.

Disclosure of Invention

The object of the present invention is therefore to overcome the disadvantages known from the prior art and in particular to provide a secondary cylinder which is as simple to produce as possible and by means of which not only the tilting of the system is reduced, but also the radial orientation/centering of the operating bearing and of the carrier element is simplified.

This is solved according to the invention by: the two single pistons are arranged with their contact regions relatively movably at least in the radial direction with respect to the contact regions on the support element side.

The actuating bearing can thereby be self-centered during operation in a simple manner. Tilting of the system is avoided. At the same time, a relatively simply producible piston unit is achieved, which has as many identical components as possible and which is coupled to the respective carrier element with relatively low effort.

Further advantageous embodiments are explained in detail below.

If three single pistons are provided in the piston unit, sufficient support of the carrier element is achieved without unnecessarily increasing the complexity of the piston unit.

It is also advantageous if a first single piston (of the piston unit) is arranged with its (first) contact region in the radial direction and in the circumferential direction fixedly with respect to the central axis of the housing on a first mating contact region of the carrier element. This ensures that the carrier element is fixed on the circumferential side and radially fixed relative to the piston unit/first single piston.

In this respect it is particularly expedient if the (first) contact area of the first single piston forms a spherical contact with the first mating contact area. The carrier element can thus pivot about the spherical contact portion/point formed between the (first) contact area and the first mating contact area of the first single piston. In this case, the first contact region is preferably formed by a (first) contact element which forms a ball/sphere on its side facing the carrier element. The first mating contact region more preferably has a recess/groove shaped complementarily to the spherical shape, which recess/groove fixedly supports the ball head in the circumferential direction as well as in the radial direction.

It is furthermore advantageous if the second single piston (of the piston unit) is arranged with its (second) contact region in a fixed manner in the circumferential/rotational direction relative to the central axis, but is arranged on the second mating contact region of the carrier element in a relatively displaceable manner in the radial direction (relative to the carrier element). The second single piston is thereby connected to the carrier element such that the carrier element can be moved in one degree of freedom relative to the second single piston. In operation, therefore, a compensating movement of the carrier element relative to the piston unit takes place around the spherical contact formed by the first contact area and the first mating contact area.

It is expedient in this respect that the (second) contact region of the second single piston is matched in shape to the second mating contact region in such a way that the (second) contact region of the second single piston can be moved (guided) along the guide rail in the radial direction relative to the second mating contact region.

It is also advantageous if the (second) contact region of the second single piston has a cylindrical surface facing the second mating contact region/carrier element, the longitudinal direction of said cylindrical surface being oriented in the radial direction. The second mating contact region in turn preferably forms a pit/groove which is formed complementarily to the (second) contact region of the second single piston, which is therefore likewise cylindrical, so that the cylindrical face which is oriented is arranged displaceably only in the radial direction within the pit of the second mating contact region. Thereby, a cylindrical contact portion is formed between the (second) contact area and the second mating contact area of the second single piston.

As an alternative to the second contact region being shaped as a cylindrical surface, it is also advantageous according to a further preferred embodiment if the (second) contact region of the second single piston has a spherical surface. The second mating contact region is preferably formed as a cylindrical pit/groove which is diametrically complementary to the (second) contact region/spherical surface of the second single piston, wherein the spherical surface is in turn arranged movably only in the radial direction within the pit of said second mating contact region. Thereby, a ball-and-cylinder contact is formed between the (second) contact area and the second mating contact area of the second single piston.

The first single piston and the second single piston are therefore always convexly shaped with respect to their (first and second) contact areas and the respective first and second mating contact areas are concavely shaped.

It is furthermore advantageous if a third single piston is arranged with its (third) contact region on/to a third mating contact region of the carrier element in a manner that it can be displaced relative to the central axis (relative to the carrier element) in the circumferential/rotational direction and in the radial direction. Thus, with regard to the third single piston, there is only axial support/fixing on the carrier element. The third single piston is thereby connected to the carrier element such that the carrier element can move with respect to the third single piston with two degrees of freedom.

In this respect it is also advantageous if the (third) contact area of the third single piston is matched in shape to the third mating contact area, so that the (third) contact area of the third single piston and the third mating contact area can freely move relative to each other in the contact plane.

It is also expedient for there to be a plane contact or a point contact or a line contact between the (third) contact region of the third single piston and the third mating contact region. The friction between the contact regions can thereby be set particularly skillfully.

If each individual piston is fixed in a movement-proof manner on the carrier element by means of the holding element, it is possible to achieve as identical a mounting of the individual pistons on the carrier element as possible. This makes it possible to use as many identical components as possible and also simplifies the production.

In this connection, it is particularly expedient if the holding means of the respective single piston is positively arranged, for example clamped, on the single piston and/or on the carrier element. This makes it possible to install the components particularly easily.

If each contact region (i.e. not only the first contact region, the second contact region but also the third contact region) of a single piston is formed by a contact element which is formed separately from the piston base body of the respective single piston, then the different single pistons only need to be configured differently with respect to their contact elements, and the remaining configurations of the single pistons can be implemented identically.

It is also advantageous in respect of the contact elements that they are received/fixed in respect of the respective single piston (preferably in respect of the holder) via a fail-safe connection. Thereby ensuring that the contact element is mounted in the correct orientation.

When a support element (preferably designed as a support plate) is provided between the piston base body and the contact element of the respective single piston, the support and mounting of the respective contact element is additionally improved. The support element supports the respective contact element on a side facing away from the carrier element. In this respect it is particularly advantageous if the contact element and the support element are supported by each other via a spherical contact. In this way, small fluctuations in the inclination position of the respective piston base body are easily corrected.

Furthermore, it is advantageous if the respective single piston, preferably the piston base body, has a plurality of, particularly preferably four, column regions, wherein the column regions all end in an imaginary reference plane and are provided for contacting regions which are fixed to the carrier element. This ensures that the respective single piston is additionally prevented from tilting relative to the carrier element.

The connection between the single piston and the carrier element is further simplified if the respective column region is directly provided with a recess for receiving the holder in a form-fitting manner.

A particularly reliable axial fixation between the single piston and the carrier element is ensured if the holder of the respective single piston is additionally fixed via a fixing element, preferably in the form of a plate, on the side of the carrier element facing away from the single piston. In this connection it is also advantageous if the fixing element is shaped such that it allows a movement of the two second and third single pistons along their degree of freedom relative to the second and third mating contact areas of the carrier element.

In addition to the single piston forming the (first) piston unit, the secondary cylinder preferably has a further annular piston forming a further (second) piston unit. The annular piston interacts in a typical manner with a further clutch again by means of a further (second) actuating bearing.

The invention also relates to an actuating device for a clutch of a motor vehicle, having a slave cylinder according to at least one of the above-described embodiments of the invention.

The invention also relates to a clutch system for a drive train of a motor vehicle, comprising a clutch and the actuating device.

In other words, therefore, a multi-piston separator (secondary cylinder) with a spherical contact surface, a planar contact surface and a cylindrical contact surface (first to third contact areas) is realized according to the invention. It is proposed that the contact between the bearing plate (carrier element) on the bearing (actuating bearing) side and the three pistons (single pistons) of the multi-piston separator be designed such that the bearing is self-centering and tilting of the system is avoided. In this case, the first piston (first single piston) is contacted via a ball, the second piston (second single piston) is contacted via a cylinder, and the third piston (third single piston) is connected to the carrier plate (each by means of a corresponding shape) via a flat, line or point contact. The contacts differ in their degrees of freedom. The shape of the carrier element on the respective single piston side also differs. This connection makes it possible for the bearing to utilize its self-centering function, since the contact of the piston to the carrier corresponds to an approximately form-fitting connection.

Drawings

The invention will now be explained in detail below with reference to the accompanying drawings.

The figures show:

fig. 1 shows a perspective view of a secondary cylinder according to a preferred embodiment of the invention from the side on which the arrangement between the individual pistons of the piston unit by means of a carrier element can be seen, wherein the actuating bearing coupled thereto in a rotationally fixed manner is not shown,

fig. 2 shows a perspective view of the slave cylinder according to fig. 1, wherein additionally no carrier element is shown, so that differently shaped contact areas of the single piston can be seen,

fig. 3 shows a perspective view of the slave cylinder according to fig. 1, wherein compared to fig. 1 the actuating bearing coupled to the carrier element is now also depicted,

fig. 4 shows a longitudinal section through the secondary cylinder according to fig. 3, wherein the section is developed, so that the section of the first single piston of the piston unit can be seen,

fig. 5 shows a longitudinal section through the secondary cylinder according to fig. 4 in the region of the first single piston, the section plane being selected such that two pin-shaped projections are shown in section, which projections serve for the positive-locking arrangement of the first single piston on the support element via the retaining means,

fig. 6 shows a longitudinal section through the secondary cylinder, wherein the sectional plane is now extended, so that a section through the second single piston of the piston unit can be seen,

fig. 7 shows a longitudinal section through the secondary cylinder in the region of the second single piston, the section plane being selected such that two pin-shaped projections of a holder are shown in section, which couples the second single piston to the support element,

fig. 8 shows a longitudinal section through the secondary cylinder in the region of the second single piston, the section plane being offset compared to fig. 8, so that one of the column regions formed on the single piston can be seen well from the side,

fig. 9 shows a longitudinal section through the slave cylinder, the section plane being selected such that a sectional view of the third piston of the piston unit is shown,

fig. 10 shows a longitudinal section through the secondary cylinder in the region of the third single piston, the section plane being selected such that two pin-shaped projections of a holder are visible, which connects the third single piston to the support element,

fig. 11 shows a perspective view of the piston base body for the first to third single pistons from the side facing the carrier element during operation, wherein the column region can also be seen,

figure 12 shows a perspective view of the piston base body according to figure 11 in a longitudinal section,

figure 13 shows a perspective view of the (first) contact area of the first contact element forming a first single piston,

figure 14 shows a perspective view of the (second) contact area of the second contact element forming a second single piston,

figure 15 shows a perspective view of the (third) contact area of the third contact element forming a third single piston,

figure 16 shows a perspective view of the carrier element applied in figures 1 to 10 from the side of the carrier element facing the single piston in the mounted state,

figure 17 shows a perspective view of the carrier element according to figure 16 from the side of the carrier element facing the steering bearing in the mounted state,

figure 18 shows a perspective view of the holder connecting the respective single piston with the carrier element in the mounted state from the side of the holder facing the carrier element in the mounted state,

figure 19 shows a perspective view of the holder according to figure 18 in longitudinal section,

fig. 20 shows a perspective view of the support element supporting the respective contact element in the mounted state from the side facing the contact element, an

Fig. 21 shows a perspective view of the fixing element, which in the mounted state locks with the projection of the holder of the third single piston.

The drawings are merely schematic and are provided for understanding the present invention. Like elements are provided with like reference numerals.

Detailed Description

In fig. 1 a slave cylinder 1 according to the invention according to a preferred embodiment is shown. In the figures, the connection between the (first) piston unit 3 of the secondary cylinder 1 and the carrier element 6 can be seen in particular, which connection is described in detail below. The slave cylinder 1 is configured as a hydraulic slave cylinder 1. The secondary cylinder 1 is realized in particular as a multiple separator. The slave cylinder 1 therefore has, in addition to the (first) piston unit 3, a further (second) piston unit 16, wherein each

piston unit

3, 16 serves for actuating a separate clutch. The secondary cylinder 1 is thus realized in a typical manner for actuating a plurality of clutches or for actuating a plurality of partial clutches of a double clutch or a triple clutch. The slave cylinder 1 is typically part of a clutch actuation system of a motor vehicle drive train during operation, which is not further shown here for the sake of clarity. The actuating system is again a component of a clutch system to which at least two clutches belong, which can be actuated by the secondary cylinder 1. The secondary cylinder 1 continues to be connected to the primary cylinder during operation with its

piston units

3, 16.

The secondary cylinder 1 basically has a housing 2 with a central through-opening 17. The through hole 17 extends along the central axis 9 of the housing 2. The housing 2 extends substantially annularly around a central axis 9. The shaft or propeller shaft of the motor vehicle drive train projects through the through-opening 17 in a typical manner during operation.

The two

piston units

3, 16 are integrated into the housing 2. The second piston unit 16 is typically designed as a CSC unit (unit having a piston 18 extending concentrically with the central axis 9). The piston 18 of the second piston unit 16, which can be seen in fig. 4, for example, is designed as an annular piston 18. The annular piston 18 is guided displaceably in an annular receiving space 19 of the housing 2. An annular pressure chamber 20 is enclosed between the annular piston 18 and the receiving space 19, wherein the annular piston 18 is moved into a position of displacement or displacement in order to actuate a clutch operatively connected to the second piston unit 16 as a function of the pressure applied there. The annular piston 18 is coupled in a typical manner to a (second) actuating bearing 21 in the form of a rolling bearing, i.e. a ball bearing, in a rotationally fixed manner.

The first piston unit 3 is arranged with its three individual pistons 4a to 4c radially outside the second piston unit 16. The first piston unit 3 is also integrated in the housing 2. In this case, three

individual pistons

4a, 4b, 4c are arranged distributed (at the same angle) along an imaginary circular line which runs around the central axis 9. Each single piston 4a to 4c is movably accommodated in a separate single chamber 22a to 22c of the housing 2. The individual chambers 22a to 22c are typically connected to a common hydraulic input. Each individual piston 4a to 4c encloses an individual pressure chamber 23a to 23c with the respective individual chamber 22a to 22 c. The three individual pressure chambers 23a to 23c are hydraulically coupled to one another.

As can also be seen particularly clearly in fig. 1, each

individual piston

4a, 4b, 4c is connected to the support element 6 in a rotationally fixed manner. The carrier element 6 is embodied as a carrier plate. As can also be seen in fig. 3, the support element 6 is connected in a rotationally fixed manner to a (first) actuating bearing 5 in the form of a rolling bearing. The first steering bearing 5 is disposed radially outward of the second steering bearing 21. The carrier element 6 is axially supported (along the central axis 9) via an annular/completely circumferential support region 24 with respect to the first actuating bearing 5. The carrier element 6 is also arranged on the first actuating bearing 5, so that a radial offset between the first actuating bearing 5 and the carrier element 6 and thus an offset of the rotational axis/center axis of the actuating bearing 5 relative to the center axis 9 is achieved.

According to the invention, each individual piston 4a to 4c is mounted/supported and coupled in a rotationally fixed manner via differently shaped contact regions 7a to 7c on mating contact regions 8a to 8c (each in the form of a projecting web) of the carrier element 6. In this case, the two single pistons, i.e. the second single piston 4b and the third single piston 4c, are arranged with their second and

third contact areas

7b and 7c, at least in the radial direction, so as to be movable relative to the two second and third

mating contact areas

8b, 8c, with respect to the central axis 9. The third single piston 4c is also arranged/accommodated (with its third contact region 7c) so as to be relatively displaceable in the circumferential/rotational direction about the central axis 9 with respect to the third mating contact region 8 c. The other (first) single piston 4a is fixedly mounted with its first contact region 7a not only in the circumferential/rotational direction but also in the radial direction of the central axis 9 on the first mating contact region 8a of the carrier element 6. The different single pistons 4a to 4c and their contact points between the contact areas 7a to 7c and the mating contact areas 8a to 8c are described in detail below.

In principle, it should be pointed out that the different single pistons 4a to 4c are of substantially identical design, but differ in their contact regions 7a to 7c or in the form of their contact elements 13a to 13c forming the contact regions 7a to 7 c. The principle configuration of the single pistons 4a to 4c described below with respect to the first single piston 4a therefore also applies to the second single piston 4b and the third single piston 4 c.

The first single piston 4a has a piston base body 14. A first contact element 13a is fixedly arranged on the piston base body 14. The first contact element 13a can also be seen in fig. 4 and 5. On the axial side facing away from the first contact element 13a, a piston seal 25 is typically arranged on the piston base body 14, said piston seal serving to seal the first pressure chamber 23a against the environment. The piston seal 25 is correspondingly guided displaceably (in the axial direction) in the first single chamber 22 a.

The first contact element 13a again has a first contact region 7a on its side facing the carrier element 6. The first contact region 7a is shaped by a spherical contact surface 27 of the first contact element 13a facing the carrier element 6. The spherical contact surface 27 can also be seen particularly well in fig. 2. The first contact region 7a is seated fixedly in the radial direction and in the circumferential direction in a first mating contact region 8a formed correspondingly thereto. The first mating contact region 8a is formed as a pit 26 (also referred to as a recess/depression) formed corresponding to the first contact region 7 a. The pit 26 is realized by a recess/pressed portion (fig. 1). The first single piston 4a is thereby fixed both radially and circumferentially to the carrier element 6. Furthermore, a spherical contact is achieved between the first contact region 7a and the first mating contact region 8 a. This means that the carrier plate 6 can be received on the first single piston 3a pivotably about a spherical contact and can thus be tilted/rotated relative to the first single piston 3 a.

The first contact element 13a is integrally formed as a ball, as can also be seen in fig. 13. The first contact element 13a is supported on its side facing away from the carrier element 6 by a separate support element 15, which is fixedly connected to the piston base body 14. The support element 15 again has, as can be seen in detail in fig. 20, a recess 28 which is formed correspondingly to the spherical surface 27 of the first contact element 13 a. Thereby achieving a spherical contact between the first contact element 13a and the support element 15. Furthermore, the support element 15 is accommodated in a recess 28 formed in the piston base body 14.

Furthermore, the first contact element 13a is guided in the direction of movement of the first single piston 4a by means of four column regions 29 as can be seen in fig. 11 and 12. In this regard, the outer circumferential side of the first contact element 13a is supported on the corresponding column region 29.

The holder 12 serves for the fixed coupling of the first single piston 4a to the carrier element 6. As can be seen from the overview of fig. 4 and 5, the holding element 12 is positively fixed directly in the region of the column region 29. For this purpose, the holding element 12, which is also shown separately in fig. 18 and 19, has a first latching region/latching projection region 30, which engages in a recess 31 of the respective post region 29. The first latching region 30 is matched to the post region 29 and its recess 31 in such a way that the holder 12 is connected axially fixed to the piston base body 14 in the installed position. The first latching region 30 extends from a disk-shaped bearing region 32 of the holder 12 toward the axial side facing the piston base body 14. The bearing region 32 is supported in the mounted state on the carrier element 6 side.

On the side of the bearing region 32 facing the carrier element 6, the retaining element 12 forms a second latching region/latching projection region 38. The two pin-like projections 33 of the second latching region 38 extend axially away from the bearing region 32. The projection 33, also referred to as a latch connecting pin, passes through the first mating contact region 8a via a receiving opening 34, as can be seen in fig. 1. The projection 33 is axially locked/positively fixed on the axial side of the first mating contact region 8a facing away from the bearing region 32. The holder 12 and thus the first single piston 4a are thereby fixedly connected in the axial direction to the carrier element 6 on the basis of its piston base body 14.

The second single piston 4b is shown in detail in fig. 6 to 8. Since the construction of the second single piston 4b is as identical as possible to that of the first single piston 4a, as already mentioned, only the differences of the second single piston 4b with respect to the first single piston 4a will be described below for the sake of brevity.

The second contact element 13b forming the second contact region 7b of the second single piston 4b is in particular different from the first contact element 13 a. The second contact element 13b can also be seen in fig. 14. The second contact element 13b now has a hemispherical surface 27, by means of which the second contact element 13b is supported on the support element 15. The second contact region 7b is cylindrically shaped. The second contact region 7b is formed by a circumferential region of the cylindrical surface 39. The cylindrical surface 39 runs with its longitudinal direction/longitudinal extension in the radial direction of the central axis 9 as can be seen in fig. 1 and 2. The second contact region 7 b/the cylindrical surface 39 is accommodated in a correspondingly shaped recess 26 (also referred to as an elongated hole) so as to be displaceable relative to one another in the radial direction. The hollows 26 of the second mating contact region 8b thus form a guide rail 10 along which the second contact region 7b is guided movably in the radial direction. The second single piston 4b is therefore fixedly connected to the carrier element 6 in the circumferential/rotational direction with respect to the central axis 9 and is supported on the carrier element 6, whereas it is accommodated so as to be relatively displaceable with respect to the carrier element 6 in the radial direction of the central axis 9. Thereby, a cylindrical contact is realized between the second contact area 7b and the second mating contact area 8 b. According to other embodiments, it is also possible to form the second contact region 7b again as a function of the first contact region 7a or to form the second contact element 13b as a whole as a ball in the same way as the first contact element 13 a.

In this connection, as can be seen in fig. 16 and 17, the respective receiving openings 34 of the second mating contact region 8b for the insertion projections 33 are configured as elongated holes due to the displaceability in the radial direction.

The third single piston 4c is shown in detail in connection with fig. 9 and 10. The third single piston 4c is likewise constructed in principle from the first single piston 4a, so for the sake of brevity only the differences between the

single pistons

4a and 4c will be described below. The third contact element 13c forming the third contact region 7c is in turn shaped differently from the first contact element 13 a. The third contact element 13c has a hemispherical surface 27, by means of which the third contact element is supported on the support element 15 (fig. 15). The third contact region 7c is in turn formed on its side facing the carrier element 6. The third contact area 7c is shaped flat as a flat face 35. The flat surface 35 is in surface contact with the mating surface 40 of the third mating contact region 8c, which mating surface is likewise designed substantially flat (alternatively, point or line contact is also possible). Whereby the third contact area 7c and the third mating contact area 8c are contacted in the contact plane 11. It is thus allowed for the third contact region 7c to be movable with respect to the third mating contact region 8c not only in the radial direction but also in the circumferential direction (inside the contact plane 11) with respect to the central axis 9 c.

To ensure this displacement, the receiving opening 34 is correspondingly large. However, in order to ensure a form-fitting connection with the holder 12, as can be seen well in fig. 1, an additional fixing element 36 in the form of a fixing plate is provided. The fastening element 36 likewise has a receiving opening 34 which interacts with the projection 33 and axially supports the projection 33 in the installed state, so that the holder 12 of the third single piston 4c is coupled in a rotationally fixed manner to the carrier element 6.

Returning to fig. 2, 18 and 19, it is also provided with respect to the holder 12 that the holder 12 has a window 37 in the bearing region 32. The window 37 is designed such that it serves to make a mistake-proof connection. The window 37 is dimensioned such that, during installation, in particular the relative rotational position and the orientation in the radial direction of the second contact element 13b and the third contact element 13c relative to the piston base body 14 and the carrier element 6 are brought into the correct position.

In other words, according to the invention, a three-piston release (slave cylinder 1) is formed, which is part of the actuating device for the partial clutch K1. There is also an actuating device for the partial clutch K2. The invention is based on the kinematic design of the three contact points between the hydraulic piston system (

single pistons

4a, 4b, 4c) and the carrier plate 6 of the bearing (first actuating bearing 5), on which the radial offset of the bearing is compensated. The piston 4a is therefore provided with a spherical contact portion. The second piston 4b is provided with a cylindrical contact portion, wherein the outer side 39 is shown facing outwards in the radial direction. The third piston 4c is provided with a planar, linear or punctiform contact. The contact points 1 and 2 (first and

second contact regions

7a, 7b) can be understood to be convex and concave, respectively. The spherical contact is thus formed by a ball which engages in the spherical recess 26 of the carrier plate 6. Likewise, the contact part 2 is formed by a cylinder which engages in a cylindrical recess 26 of the carrier plate 6. The concave fitting shape is left aside in the carrier plate 6 only at the contact portions 3 (third contact areas 7 c). Here, a line contact, a point contact, or a surface contact is considered.

The multiple piston system K1 (first piston unit 3) is divided into three piston assemblies (

single pistons

4a, 4 c). This ensures, with an optimal positioning: the engagement bearing K1 always or mostly reaches the center of rotation of the clutch. In this case, the effects resulting from the unknown friction values between the different components, the different thermal expansions and tolerances are taken into account as interference variables. The following kinematic scheme is therefore also proposed: when the clutch is in contact with the outer ring K1, a floating contact is provided, which in the non-actuated state is acted upon solely by the preload of the clutch. When the release bearing 5 is in contact with the carrier plate 6, a preloaded contact is provided (radial offset compensation). When the carrier plate 6 is in contact with the

pistons

4a, 4b, 4c, an approximately stationary system is proposed. This system is constituted by a spherical contact in which the piston 4a carries a ball which engages into a corresponding shape in the carrier plate 6. The contact portion positions the carrier plate 6. The tilt and rotational degrees of freedom have not been determined. The system is formed by a cylindrical contact, the outer side 39 of which protrudes outwards in the radial direction (wei β t). The contact portion determines the degree of freedom of rotation. Also considered are balls which extend in a cylindrical surface. The system is formed by a planar contact which excludes tilting of the system and blocks the last degree of freedom. Point contacts or line contacts are also conceivable here.

This arrangement results in a characteristic when three or more pistons are applied, which can be similar to a normal CSC, which involves the bearing 5 self-centering on the centre of rotation. By the quasi-static nature, or by approximately determining the friction value 1 (blocking) when the carrier plate 6 is in contact with the piston, the centering function takes place in the position provided for this: in the radial misalignment compensation of the bearing 5.

A quasi-static contact, which is formed by the contact regions 7a to 7c and the mating contact regions 8a to 8c, is realized in order to define, on the one hand, a position in which the bearing 5 can reach its position. It is necessary for this purpose that the force for eccentricity is greater during contact than during radial misalignment compensation. At the same time, compensation for manufacturing tolerances and for possible different thermal expansions is required in the contact 4. In this regard, the contact formed by a/b/c (7a to 7c and 8a to 8c) provides the necessary degree of freedom, although it represents a corresponding blocking of the contact with respect to the self-centering of the bearing 5. The matching therefore takes place in the respective single contact during thermal expansion or during tolerance compensation. The spherical contact portion (the first contact area 7a with the first mating contact area 8a) always defines the radial position of the system. It causes, for example, the carrier 6 to be eccentric with respect to the carrier plate 6 (steel) when the housing 2 (plastic) expands (temperature). This expansion or eccentricity is resisted by other contacts. This contact (second contact region 7b with second mating contact region 8b) therefore only determines the circumferential orientation of the carrier plate 6 via the cylinder. But does not block the radial position of the cylinder but opens its radial position so that a new position is reached when the cylinder is expanded. In the case of an angular error of the cylindrical surface in the carrier plate 6, the piston 4b carrying the contact 7b compensates the angular error by slight rotation, but the cylinder is otherwise oriented approximately in its angular position in the piston 4 b. The contact 7c (the third contact area 7c with the third mating contact area 8c) has no resistance to movement to the subject thermal expansion at all, since it is only in planar abutment. When compensating for thermal expansion, the contact part corresponding to the ball, for example the bearing 5, is pulled out of the center of rotation together with the carrier plate 6. On the next actuation, however, the bearing 5 again reaches its position in the center of rotation of the clutch via radial misalignment compensation.

It is furthermore mentioned that the

components

13b and 13c each have the shape of a sphere on their side facing the piston, which makes it possible to use the same component 15 for all the contact points and to compensate slight angular errors in the system in this spherical contact point. Furthermore, the possible tilting gap is delimited in the component 14 (piston) by four columns (column regions 29). These columns 29 are preloaded during operation or pressed by the pressure in the pressure chamber during operation against the carrier plate 6. When the tilting now occurs, these posts 29 strike the carrier plate 6 according to the embodiment or, as the case may be, the component 12 resting on the carrier plate 6. This produces a force which acts counter to the tilting force and prevents tilting. In the variant shown, the preload is applied to the system by means of a clutch. This preload is supported on the housing 2 via the following sequence of components: bearing K15 → carrier plate 6 →

members

13a, 13b, 13c → support plate 15 → piston (piston base 14). When pressure is applied, forces are applied in reverse order via the seal and the piston.

List of reference numerals

1 auxiliary cylinder

2 casing

3 first piston unit

4a first single piston

4b second Single piston

4c third Single piston

5 first control bearing

6 bearing element

7a first contact area

7b second contact area

7c third contact area

8a first mating contact area

8b second mating contact area

8c third mating contact area

9 central axis

10 guide rail

11 plane of contact

12 holder

13a first contact element

13b second contact element

13c third contact element

14 piston base

15 support element

16 second piston unit

17 through hole

18 ring piston

19 accommodating cavity

20 pressure chamber

21 second steering bearing

22a first single chamber

22b second single chamber

22c third Single Chamber

23a first pressure chamber

23b second pressure chamber

23c a third pressure chamber

24 support area

25 piston seal

26 pits

27 spherical surface

28 recess

29 column region

30 first latching region

31 groove

32 support area

33 raised part

34 receiving hole

35 plane

36 securing element

37 window

38 second latching region

39 cylindrical surface

40 mating surfaces.

Claims

1. A secondary cylinder (1) for a clutch actuating device of a motor vehicle, having a housing (2), a piston unit (3) which has a plurality of single pistons (4a, 4b, 4c) accommodated in the housing (2) and which, in operation, acts in an adjusting manner on an actuating bearing (5) in order to self-center the actuating bearing, and having a carrier element (6) which couples the single pistons (4a, 4b, 4c) to the actuating bearing (5), wherein each single piston (4a, 4b, 4c) is supported in a non-moving manner on a mating contact region (8a, 8b, 8c) on the carrier element (6) by means of a contact region (7a, 7b, 7c),

characterized in that the two single pistons (4b, 4c) are arranged with their contact areas (7b, 7c) relatively displaceable at least in the radial direction with respect to the mating contact area (8b, 8c) of the carrier element (6).

2. The slave cylinder (1) according to claim 1, characterized in that a first single piston (4a) is fixedly arranged with its contact area (7a) in the radial direction and in the circumferential direction relative to the central axis (9) of the housing (2) on a first mating contact area (8a) of the carrier element (6).

3. The slave cylinder (1) according to claim 2, characterized in that the contact area (7a) of the first single piston (4a) forms a spherical contact with the first mating contact area (8 a).

4. The slave cylinder (1) according to any one of claims 1 to 3, characterised in that a second single piston (4b) is seated with its contact region (7b) on a second mating contact region (8b) of the carrier element (6) fixedly in the circumferential direction relative to the central axis (9) of the housing, but relatively movably in the radial direction.

5. The slave cylinder (1) according to claim 4, characterized in that the contact area (7b) of the second single piston (4b) matches in shape the second mating contact area (8b) such that the contact area (7b) of the second single piston (4b) is movable along a guide rail (10) in radial direction relative to the second mating contact area (8 b).

6. The slave cylinder (1) according to any one of claims 1 to 3, characterised in that a third single piston (4c) is seated with its contact region (7c) on a third mating contact region (8c) of the carrier element (6) relatively movably in the circumferential direction and in the radial direction with respect to the central axis (9) of the housing.

7. The slave cylinder (1) according to claim 6, characterized in that the contact area (7c) of the third single piston (4c) matches in shape the third mating contact area (8c) such that the contact area (7c) of the third single piston (4c) and the third mating contact area (8c) are free to move relative to each other in a contact plane (11).

8. The slave cylinder (1) according to any one of claims 1 to 3, characterised in that each single piston (4a, 4b, 4c) is fixed in a movement-resistant manner on the carrier element (6) by means of a holder (12).

9. An actuating device for a clutch of a motor vehicle, having a secondary cylinder (1) according to at least one of claims 1 to 8.

10. A clutch system for a drive train of a motor vehicle, having a clutch and an actuating device according to claim 9.