GB2272952A

GB2272952A - A pull type clutch actuator having telescopic spring supports

Info

Publication number: GB2272952A
Application number: GB9323502A
Authority: GB
Inventors: Gottfried Mader; Wolfgang Grosspietsch; Herbert Voit; Manfred Wehner
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1992-11-14
Filing date: 1993-11-15
Publication date: 1994-06-01
Anticipated expiration: 2013-11-15
Also published as: GB9323502D0; DE4338262C2; DE4338262A1; GB2272952B

Abstract

A hydraulic actuator for a pulled friction clutch comprising a cylinder 3 and a bearing support 5 having a map-action connection 43, 45 with a spring support 35 so as to improve assembly. A tension spring 33 is connected via a further spring support 37 to the cylinder 3 and via support 35 to the bearing support 5. Simple assembly of the supports 35, 37 is achieved, whereby at the same time the supports 35, 37 are used as a protective covering for the spring 33 and the working surface 17 of the cylinder 3, by the supports 35, 37 being constructed as tubular telescopic sleeves. The spring 33 is held in position on the supports 35, 37 by projections 51, 53 and the support 37 is braced by a shoulder 49 of the cylinder 3 which is fixed to the gearbox housing. Hydraulic aperture 29 is sealed by rings 25, 27. The bearing support 5 is radially braced by guide rings 21, 23 of plastics material. Supports 35, 37 are constructed as synthetic plastics mouldings. <IMAGE>

Description

An hydraulically operable system for disengaging a pulled friction clutch The invention relates to an hydraulically operable system for disengaging a pulled friction clutch in which a cylinder and, disposed at a radial distance therefrom, a bearing support are disposed concentrically of the gearbox input shaft and the cylinder is fixed on the gearbox, whereby a tension spring is connected by a spring support to the cylinder and by a further spring support to the bearing support.

Hydraulically actuated means of disengaging pulled motor vehicle clutches are already known (e.g. DE-GM 9100 927), in which a bearing support used as a piston encloses the clutch release bearing, whereby its inner ring comprises a groove engaged in snap-action manner by a device mounted on a diaphragm spring of the clutch. Via spring supports, a tension spring is connected to a housing forming a cylinder and defining together with the piston a pressurised hydraulic space and it serves as an initial loading spring for the clutch release bearing. The fitting of such an initial loading spring is difficult since it is necessary first to mount the tension spring together with the rear spring support on the already installed disengaging system and secure it by an appropriate locking ring. Subsequently, the front spring support has to be connected to the cylinder.Another disadvantage is the fact that the initial loading spring is unprotected inside the bearing support.

The object of the invention is to provide an hydraulically operable system for disengaging a pulled friction clutch of a motor vehicle, the components of which can be assembled more easily than hitherto.

The invention is based on an hydraulically operable system for disengaging a pulled friction clutch which comprises: a clutch release bearing disposed centrally of an axis of rotation, enclosing the axis of rotation, two axially mutually displaceable and substantially tubular disengaging components of which a first disengaging component can be fixed on a component which is stationary in relation to the friction clutch, particularly a housing of a gear mechanism which has its input shaft connected to the friction clutch and of which a second disengaging component carries the clutch release bearing and which, together with the first disengaging component, defines in sealed manner a pressurised hydraulic space, and an initial load spring constructed in particular as a tension spring and connected via respective spring supports to the first and the second disengaging component and tensioning the second disengaging component, particularly in the disengaging direction of the friction clutch.

The improvement according to the invention resides in that one of the two disengaging components and of the spring supports connecting the initial loading spring to it comprise mutually associated snap-action connection members which maintain the spring support on this disengaging component.

Where the disengaging systems according to the invention are concerned, these are disengaging systems of the annular cylinder type in which, in contrast to the slave cylinders which are conventional, the initial loading spring is of substantial diameter and is disposed outside the pressurised hydraulic space. Upon actuation of a pulled friction clutch, the initial loading spring provides for a compensation of clearance between the connecting means coupling the disengaging members of the friction clutch, for example its diaphragm spring tongues to the clutch release bearing, these normally being snap-action connection means. The compensation for clearance ensures a reduction in wear and tear on the snap-action connection means.Since at least one of the spring supports of the initial loading spring is for its part fixed by snap-action connection means, the initial loading spring is very easily fitted, even if it is disposed radially within the disengaging system and the spring support is to be mounted at some location which is comparatively difficult of access.

Ideally, at least one of the two spring supports, preferably the spring support which carries the snap-action connecting members, is constructed as a tubular sleeve which in an axial direction at least partially overlaps the initial loading spring on the side which is radially remote from the disengaging components. By virtue of its sleeve form, not only is the initial loading spring protected from damage but also the sleeve can be used as a handling element which facilitates fitting of the spring support.

In a preferred development, both spring supports are constructed as tubular sleeves and are adapted for telescopic inter-engaging displacement. Ideally, the arrangement is such that the sleeves are so long in an axial direction that they axially overlap in both extreme relative positions of the two disengaging components which represent the clutch disengaged position and the clutch engage position of the friction clutch. This developed embodiment permits not only of a space-saving disposition of the initial loading spring but on the one hand protects the initial loading spring and on the other possibly exposed sliding surfaces of the disengaging components.It is particularly advantageous also that the spring support can be fitted together with the initial loading spring as one component unit, for example in that this component unit is pushed axially onto or into the disengaging component which has to be connected by the snap-action connection and is fixed thereon by the snap-action connection. The tubular sleeves of the spring supports have in other words and at the same time the function of protective covers.

Such protective covers can be inexpensively produced from synthetic plastics materials by an injection moulding process.

Ideally, the second disengaging component which carries the clutch release bearing coaxially engages the stationary first disengaging component so that the pressurised hydraulic space is formed radially between the inner periphery of the first disengaging component and the outer periphery of the second disengaging component. Where the initial loading spring is concerned, this is preferably a coiled tension spring and the previously described sleeves forming the protective covers ideally extend radially within the coil spring, the snap-action connecting members being provided on the second disengaging component and the spring support associated with it.

Where such an embodiment is concerned, it has been found to be favourable for the sleeve connected to the first disengaging component to have at the end a radially projecting flange which is axially braced on an annular shoulder on the first disengaging component. In such a developed embodiment, the initial loading spring can be installed with particular ease.On the other hand, the angled-over portion at the end occludes the aperture remaining between the sleeves of the spring support and of the first disengaging component and allows a sealing of the end bore of the first disengaging component constituting the cylinder, so that the working surface of the cylinder is guided for axial displacement on the second disengaging component which is used as a piston or bearing support if, as already indicated, the initial loading spring is disposed radially between the disengaging components and the sleeves which constitute the protective covers.

In a further essential development, it is envisaged that at least one of the tubular spring supports has at least one radially extending projection which serves as a bracing surface for the initial loading spring. In this case, with an initial loading spring constructed as a coil spring, the projection expediently extends likewise helically along the tubular wall of the spring support and in fact it has a direction of twist which is the, same as that of the coil spring. The coil spring which in the preferred embodiments of the invention is biased for tension can be fitted on the projections by being turned into the spring support. Where the snap-action connection members of the spring support are concerned, these are expediently one or a plurality of axially extending spring tongues with which snap-action recesses on the second disengaging component are associated. The spring tongues permit of easy axial fitment, in so far as they are pressed radially inwardly after radially outwardly resiliently projecting means and remain in this position until they have reached the snap-action recesses of the second disengaging component. The spring tongues can spring out radially into the snap-action recesses and in this way can axially secure the spring support.

In a preferred development embodiment in which the spring support is again constructed as a sleeve which engages the second disengaging component it is envisaged that this sleeve have at its end which is axially remote from the clutch release bearing an annular pocket into which the initial loading spring axially engages, its radially outer wall radially guiding the sleeve in the second disengaging component. In this case, the spring tongues are disposed on the radially outer wall of the pocket and, as explained previously, project radially outwardly. The pocket makes it possible to guide the initial loading spring at a radial distance from the two disengaging components and it is particularly advantageous in the case of embodiments in which the spring supports form the aforementioned protective covers.

Under a further aspect of the invention, an hydraulically operable system for disengaging a pulled friction clutch is provided in which the spring supports can not only be produced inexpensively for the initial loading spring and easily assembled but are at the same time constructed as protective covers for the initial loading spring. From the second point of view, the invention is based on a disengaging system in which a cylinder and a bearing support disposed at a radial distance therefrom are disposed concentrically in relation to the gearbox input shaft and the cylinder is mounted on the gearbox, a tension spring being connected via a spring support to the cylinder and to the bearing support via a further spring support.The improvement according to the invention resides in the fact that the spring supports are constructed as tubular telescopically inter-engagably displaceable sleeves, whereby the spring support which is connected to the bearing support forms a snap-action connection together with the bearing support. Also from the second aspect of the invention, the aforementioned advantages are provided.

The aforedescribed advantageous alternative embodiment of the invention can be used also in the case of disengaging systems according to the second aspect whereby in this connection the first disengaging component forms the cylinder while the second disengaging components form the bearing support.

Examples of embodiment of the invention are explained in detail hereinafter with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section through an hydraulic disengaging system for a pulled friction clutch of a motor vehicle, shown in different operating posi tions in the upper and lower halves of the drawing; Fig. 2 is a longitudinal section through the disengaging system in Fig. 1, shown in its two extreme positions, which represent the engaged position of the friction clutch (upper half) and the disengaged position of the friction clutch (bottom half), and Fig. 3 shows a longitudinal section through an alternative embodiment of the disengaging system, again in two different operating positions.

The system of disengaging a pulled friction clutch, shown in Figs. 1 and 2 of a motor vehicle (not shown) comprises two substantially tubular and in the direction of an axis of rotation 1, relatively mutually displaceable disengaging components of which a first disengaging component is formed by a cylinder 3 used as a housing while the second component is a bearing support 5 disposed for displacement in the cylinder 3. The housing 3 is stationary in its fitment on a gearbox housing not shown in greater detail and which is part of a motor vehicle gear mechanism which follows the friction clutch in the flow of driving power and, together with the bearing support 5, it encloses a gearbox input shaft (not shown) which is connected to the friction clutch equi-axially with the axis of rotation 1 and together with the bearing support 5.For its part, the end of the bearing support 5 which is axially towards the friction clutch engages around a clutch release bearing 7 of which the outer ring 9 is axially fixed on the bearing support 5 while in per se known manner its inner ring 11 comprises snap-action connection members 13 for coupling the clutch release bearing 7 to disengaging members of the friction clutch, for example the spring tongues of a diaphragm spring indicated at 15.

The cylinder 3 has an inner cylindrical surface 17 which at a radial distance is opposite an outer cylindrical surface 19 of the bearing support 5. At the clutch end of the cylinder 3 on the one hand and at the gearbox end of the bearing support 5 on the other there are axially fixed guide rings 21, 23 via which the bearing support 5 is radially braced against the cylinder 3. Radially between the cylindrical surface 17, 19 and axially between the guide rings 21, 23 produced for instance from a synthetic plastics material with favourable sliding properties and sealed by the sealing rings 25, 27 there is a pressurised hydraulic space 29 with which an hydraulic connection 31 is associated.As can best be seen from the top part of Fig. 2, the spring tongues 15 of the diaphragm spring of the clutch, when the friction clutch is engaged, maintain the bearing support 15 in a position in which it is withdrawn from the cylinder 3, a position in which the pressurised space 29 is at its minimum volume. When pressure is applied to the pressurised space 29 (Fig. 2, bottom), this is expanded and against the restoring force of the spring tongues 15, it pulls the bearing support 5 substantially completely into the cylinder 3.

In order to avoid axial clearance of the clutch release bearing 7 and of the snap-action connecting members 13 and in order thus to reduce possible wear and tear on these elements, there is clamped between the cylinder 3 and the bearing support 5 an initial loading spring 33 which is constructed as a tension-loaded coil spring, the axial ends of which are in each case supported in a spring support 35, 37 respectively. The spring supports are constructed as telescopically inter-engaging sleeve-like protective covers which radially inwardly, i.e. from the side radially remote from the cylinder 3 and the bearing support 5, mask radially inwardly the initial loading spring 33 which is enclosed both by the cylinder 3 and also the bearing support 5. The spring support 5 associated with the clutch end of the initial loading spring 5 forms an axially open pocket 39 engaged by the initial loading spring 33 and of which the radially outer wall 41 radially guides the spring support 35 on the inner periphery of the bearing support 5.

Projecting resiliently and radially outwardly from the wall 41 and distributed in a peripheral direction there are a plurality of axially extending spring tongues 43 which engage in a snap-action manner in associated catch recesses 45 on the inner periphery of the bearing support 5. The spring support 37 associated with the gearbox end of the initial loading spring 33 is provided with a radially outwardly projecting flange area 47 with which it is axially braced via a shoulder 49 of the cylinder 3 directed towards the gearbox and annularly surrounds the cylindrical surface 17. The two spring supports 35, 37 are, for fixing means, provided with radial webs or projections 51, 53 behind which engage the end turns of the initial loading spring 33.

As can best be seen from Fig. 2, the inter-engaging telescopic sleeve-like portions of the spring supports 35, 27 are so dimensioned axially and radially that in any operating position they completely mask not only the initial loading spring 33 but also the inner cylindrical surface 17 of the cylinder 3. Complete masking is also provided by the closed annular flange 47 of the spring support 37. The two spring supports 35, 37 are constructed as synthetic plastics mouldings and can together with the initial loading spring 33, be combined into one component unit which can be incorporated as such into the disengaging system. For this purpose, the component unit only needs to be fitted into the bearing support 5 together with the spring support 35 until the spring tongues 35 snap into position in the catch recesses 45 in the bearing support 5.

The sleeve-like portions of the spring supports 35, 37 guided radially on one another in a sleeve-like manner facilitate this process.

The embodiment of disengaging systems shown in Fig. 3 differs from that in Fig. 1 only in that the webs or projections 51, 53 provided for fixing the end turns of the initial loading spring 33 on the again sleeve-like spring supports 35, 37 have helical patterns extending with the direction of turn as the initial loading spring 33 and, as Fig. 3 shows, preferably by more than one turn of the initial loading spring 33. The initial loading spring 33 can thus turn into the spring supports 35, 37 by more than one turn, so that the bracing surface is enlarged and axial safeguarding of the initial loading spring 33 is improved.

With regard to a description of the rest of the construction and mode of operation of the disengaging system, reference is made to the description of Figs.

1 and 2.

Claims

PATENT CLAIMS

1. An hydraulically operable system for disengaging a pulled friction clutch in which a cylinder (3) and, disposed at a radial distance therefrom, a bearing support (5) are disposed concentrically of the gearbox input shaft and the cylinder (3) is fixed on the gearbox, whereby a tension spring (33) is connected by a spring support (37) to the cylinder (3) and by a further spring support (35) to the bearing support (5), characterised in that the spring supports (35, 37) are constructed as tubular telescopically inter-engagable sleeves, the spring support (35) which is connected to the bearing support (5) forming a snap-action connection together with the bearing support (5).

2. A disengaging system according to claim 1, characterised in that at least one spring support (35, 37) comprises at least one extending projection (51, 53) which serves as a bracing surface for the tension spring (33).

3. A disengaging system according to claim 2, characterised in that the projection (51, 53) extends helically on the outer surface of the spring support (35, 37) in keeping with the pitch of the tension spring (33).

.

4. A disengaging system according to one of claims 1 to 3, characterised in that the spring support (35) which is connected to the bearing support (5) has at least one radially outwardly projecting spring tongue (43) which engages a corresponding recess (45) in the bearing support (5).

5. A disengaging system according to one of claims 1 to 4, characterised in that the spring support (37) which is connected to the cylinder (3) has at the end an angled over portion (47) which corresponds to the aperture in the cylinder (3).

6. A disengaging system according to one of claims 1 to 5, characterised in that the spring supports (35, 37) are disposed at a distance radially within the bearing support (5) and in that the tension spring (33) extends between the spring supports (35, 37) and the bearing support (5).

7. A disengaging system according to one of claims 1 to 6, characterised in that the spring supports (35, 37) which extend in a sleeve-like manner are provided as protec tive covers for the faying surfaces of the cylinder (3) and of the tension spring (33).

8. An hydraulically operable disengaging system for a pulled friction clutch of a motor vehicle comprising: - a clutch release bearing (7) disposed centrally of a axis of rotation (1), - enclosing the axis of rotation (1), two axially mutually displaceable and substantially tubular dis engaging components (3, 5) of which a first disengaging component (3) can be fixed on a component which is stationary in relation to the friction clutch, particularly a housing of a gear mechanism which has its input shaft connected to the friction clutch and of which a second disengaging component (5) carries the clutch release bearing (7) and which, together with the first disengaging component (3) defines in sealed manner a pressurised hydraulic space (29), and - an initial load spring (33) constructed in particular as a tension spring and connected via respective spring supports (35, 37) to the first (3) and the second (5) disengaging component and tensioning the second disengaging component (5) particularly in the disengaging direction of the friction clutch, characterised in that one (5) of the two disengaging components (3, 5) and the spring support (35) connecting the initial load spring (33) to it comprise mutually associated snap-action connecting members (43, 45) which maintain the spring support (35) on this disengaging component (5).

9. A disengaging system according to claim 8, charac terised in that at least one of the two spring supports (35, 37) is constructed as a tubular sleeve which in an axial direction at least partially overlaps the initial load spring (33) on the side radially remote from the disengaging components (3, 5).

10. A disengaging system according to claim 9, charac terised in that both spring supports (35, 37) are constructed as tubular sleeves and are adapted for telescopic inter-engaging displacement.

11. A disengaging system according to claim 10, charac terised in that the axial length of the sleeves is so dimensioned that the sleeves axially overlap in both extreme relative positions of the two disengaging components (3, 5) which represent the clutch disengaged position and the clutch engaged position of the friction clutch.

12. A disengaging system according to claim 10 or 11, characterised in that the second disengaging component (5) coaxially engages the first disengaging component (3) and the pressurised hydraulic space (29) is disposed radially between the inner circumference (17) of the first disengaging component (3) and the outer circumference (19) of the second disengaging component (5) and in that the initial load spring (33) is con structed as a coiled tension spring and the sleeves extend radially within the coil spring, the snap-action connecting members (43, 45) being provided on the second disengaging component (5) and the spring support (35) associated with it.

13. A disengaging system according to claim 12, charac terised in that the sleeve connected to the first disengaging component (3) has at the end a radially projecting flange (47) which is axially braced on an annular shoulder (49) on the first disengaging component (3).

14. A disengaging system according to one of claims 8 to 13, characterised in that each spring support (35, 37) has a tubular shape and comprises at least one radially extending projection (51, 53) which serves as an axial bracing surface for the initial load spring (33).

15. A disengaging system according to claim 14, charac terised in that the initial load spring (33) is constructed as a coil spring and in that the projection (51, 53) extends helically along a tubular wall of the spring support (35, 37), the direction of twist being the same as that of the coil spring.

16. A disengaging system according to one of claims 8 to 15, characterised in that the snap-action connecting member of the spring support (35) has at least one axially extending spring tongue (43) with which a snap action recess (45) on the second disengaging component (5) is associated.

17. A disengaging system according to claim 16, charac terised in that the spring support (35) carrying the spring tongues (43) is constructed as a sleeve which engages the second disengaging component (5) and has at its end axially remote from the clutch release bearing (7) an annular pocket (39) into which the initial load spring (33) axially engages, its radially outer wall (41) radially guiding the sleeve in the second disengaging component (5), each spring tongue (43) being disposed on the radially outer wall (41) and projecting radially outwardly.

18. A disengaging system according to one of claims 8 to 17, characterised in that the spring supports (35, 37) are constructed as synthetic plastics mouldings.

19. An hydraulically operable system for disengaging a friction clutch substantially as described with reference to and as illustrated in Figures 1 and 2 or Figure 3 of the accompanying drawings.