GB2248477A

GB2248477A - A process for assembling a friction clutch unit and a friction clutch unit which can be assembled by the process.

Info

Publication number: GB2248477A
Application number: GB9109813A
Authority: GB
Inventors: Holger Westendorf; Andreas Krause; Friedrich Kittel
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1990-05-07
Filing date: 1991-05-07
Publication date: 1992-04-08
Anticipated expiration: 2011-05-07
Also published as: GB9109813D0; FR2661723B1; DE4014471C2; BR9101821A; GB2248477B; FR2661723A1; DE4014471A1

Description

1 A PROCESS FOR ASSEMBLING A FRICTION CLUTCH UNIT AND A FRICTION CLUTCH

UNIT WHICH CAN BE ASSEMBLED BY THE PROCESS The invention relates to a method for assembling a friction clutch unit and to a friction clutch unit which can be assembled by the method.

A friction clutch unit (modular clutch) is known from DE-A-33 43 506, which comprises a flywheel, a clutch housing fastened on the flywheel, a pressing plate which is nonrotatably but axially movably guided on the clutch housing, a clutch disc arranged with its friction linings axially between the flywheel and the pressing plate and a clutch main spring arrangement tensioning the pressing plate against the flywheel via the friction linings. During assembly of the known clutch, the clutch housing, the pressing plate and the clutch main spring arrangement formed by a diaphragm spring are firstly pre-assembled to form a pressure plate unit which is then applied to the flywheel with interposition of the clutch disc. For fastening purposes, the clutch housing is bent twice through 900 round a rib or flange of the flywheel. The pressing force of the diaphragm spring can be adjusted to a certain extent by adjusting the bending force.

An object of the invention is to improve the known process for assembly such that the pressing force at which the clutch main spring arrangement is prestressed when the friction clutch is engaged can be adjusted more precisely than hitherto to a predetermined pressing force value. A further object of the invention is to provide a friction clutch which can be assembled particularly advantageously by the process according to the invention.

The invention is based on a process for assembling a friction clutch of the aforementioned type, in which the clutch main spring arrangement has a predetermined pressing 2 force/spring travel characteristic and is prestressed to a predetermined pressing force value when the friction clutch is engaged and in which the following process steps are carried out:

pre-assembly of the clutch housing, pressing plate and clutch main spring arrangement to form a pressure plate unit; b) application of the pressure plate unit onto the flywheel and interposition of the clutch disc; fastening of the clutch housing on the flywheel.

According to the invention, the following process steps are proposed for assembling a friction clutch in which the axial tolerances of the pressure plate unit, the clutch disc and the flywheel are adapted to one another such that process step c) leads to a pressing force of the clutch main spring arrangement which is lower than the predetermined pressing force value:

d) measurement of the pressing force of the clutch main spring arrangement while the pressure plate unit is moved against the force of the clutch main spring arrangement into a predetermined axial position relative to the flywheel in step b); e) determination of the axial residual path over which the pressure plate unit is to move, based on the predetermined axial position relative to the flywheel, when the clutch main spring arrangement is to be prestressed to the predetermined spring force value, more specifically as a function of the predetermined pressing force/spring travel characteristic; and f) axial shifting of the clutch housing fastened on the flywheel in step c) with plastic deformation of the clutch housing by the residual path determined in step e) relative to the flywheel.

3 With this process, the pressure plate unit of the friction clutch is placed on the flywheel together with the associated clutch disc, the contact faces of the clutch housing and of the flywheel which are intended to contact one another still being at a relatively great distance from one another as the clutch main spring is in the relaxed state. By loading the clutch housing toward the supported flywheel by exertion of force, it is possible to measure the spring characteristic as a function of the path covered. The housing of the pressure plate is now moved toward the flywheel until there is a short distance between the contact faces of housing and flywheel, and the spring force trend is determined. With knowledge of the spring force trend over the entire spring travel, it is possible to determine the amount by which the clutch housing still has to be moved toward the flywheel in order to maintain the desired initial tension of the clutch main spring which is established quite exactly for various reasons. For this purpose, however, the axial tolerances of pressure plate and clutch disc relative to the flywheel have to be set such that the pressing force of the clutch main spring still lies slightly below the proposed value after the two elements have been fastened. Therefore, the overall axial displacement still required for the clutch housing can be established from the known spring force characteristic at the moment of the last measurement of force. This is accordingly composed of the residual path still available between the contact faces at the moment of measurement and the deformation path. The residual path is covered after the last measurement of force, until the contact faces come into contact with one another and is recorded exactly. The clutch housing is then fastened on the flywheel and the axial shifting of the housing in the direction of the flywheel subsequently takes place over the deformation path by plastic deformation.

4 According to a further process for assembling a friction clutch, it is proposed that the spring force trend be monitored during assembly up to the point at which the contact faces touch one another. This can be carried out, for example, by evaluating the force trend over the travel, more specifically to the point at which a kink with a subsequent substantially steeper characteristic trend appears owing to exact contact of the contact faces in the characteristic curve. It is thus possible to establish the deformation path still to be covered and to cover this deformation path by plastic deformation of the clutch housing after the clutch housing and flywheel have been fastened.

The accuracy of the basic adjustment of the initial tension of the main spring of a friction clutch increases quite considerably as a result of the two proposed processes. owing to the spring force trend of the pressure plate unit already known prior to assembly and owing to the incorporation of the clutch disc pertaining to a pressure plate unit, it is possible still to remain slightly below the proposed initial tension value, with suitable tolerances between the individual components, in particular in an axial direction, after assembly of pressure plate and flywheel, with the result that the residual path can be adjusted exactly by plastic deformation of the clutch housing toward the flywheel.

The clutch module obtained in this way is screwed as a complete unit, which will no longer be influenced, onto the crankshaft of the internal combustion engine.

The clutch housing... be constructed advantageously in different ways. Thus, it is possible, on the one hand, to provide, in the clutch housing between fastening flange and supporting point for the clutch main spring, an encircling, substantially Vshaped groove, in the region of which plastic deformation takes place. However, it is also possible to carry out plastic deformation directly radially inside the fastening zone of the flange in that the flywheel forms an edge at this position and has an offset face and the former for the plastic deformation of the clutch housing engages with a projection radially inside the shoulder. According to a further variation, the fastening flange is provided in each case in the region of the proposed fastening screws with partial faces which project beyond the contour of the fastening flange toward the flywheel and the plastic deformation of the clutch housing takes place in the region radially outside these partial faces in each case. Plastic deformation, which has substantially no repercussions, of the clutch housing is achieved'in this way.

The invention is described in more details hereinafter with reference to several embodiments.

Figure 1 is a partial longitudinal section through a clutch module in the finally adjusted position, already mounted on an internal combustion engine.

Figure 2 is a partial section through a variation of a clutch module with a substantially V-shaped deformation region, also in the operating position.

Figure 3 is a partial section with partial deformation regions concentrically to the fastening screws in each case in the operating position.

Figure 4 is an enlarged view of a partial section similar to Figure 3 in an assembly position during the measuring process.

Figure 1 shows the upper half of a longitudinal section through a friction clutch 1 in the operating position. A 6 carrier disc 6 onto which the complete friction clutch 1 can be screwed in the form of a module is screwed on a crankshaft 5 of an internal combustion engine. The friction clutch 1 comprises a flywheel 2, a clutch housing 9, in the present case a diaphragm spring 10 as a clutch main spring which is pivotally mounted via spacer bolts 13 and wire rings on the clutch housing 9, a pressing plate 8 which is fastened on the clutch housing 9 in a non-rotatable but axially shiftable manner not shown in detail (for example via tangential leaf springs), and a clutch disc 4 which is clamped between pressing plate 8 and flywheel 2. The clutch housing 9 has, in its radially outer region, a fastening flange 18 which, in the assembled state, rests with its contact face 12 on a contact face 11 of the flywheel 2. Both faces 11 and 12 extend radially. For fastening purposes, fastening screws 19 are distributed round the periphery in the present case. The illustration also shows a former 16 which surrounds the contour of the clutch housing 9 radially outside the spacer bolts 13 and rests with an encircling projection 20 on the flange 18, more specifically in its region radially inside the fastening screws 19. All components of the friction clutch 1 are rotatably arranged round an axis of rotation 7. The pressure plate unit 3 consisting of the clutch housing 9, the diaphragm spring 10 and the pressing plate 8 exists as a prefabricated component. The contact face 11 of the flywheel 2 extends radially inwardly to a diameter which is somewhat smaller than the average diameter of all heads of the fastening screws 19. A shoulder 21 is provided in the flywheel 2 at this position so that an offset face 14, which is offset from the former 16 - relative to the contact face 11 - is formed radially inside this shoulder. The resultant recess is required during assembly of the friction clutch in order plastically to deform the clutch housing 9 in this direction.

7 The assembly process is as follows: a clutch disc 4 is inserted into the axially supported flywheel 2 and the preassembled pressure plate unit 3 is applied thereto from the arrow side. In this assembly state, the diaphragm spring 10 is relaxed and a relatively large gap therefore exists between flange 18 and contact face 11. A force of increasing value is now exerted from the arrow side onto the applied former 16 either until perfect contact between the contact faces 11 and 12 is achieved or until just before such contact. The force measured in the final state is below the necessary initial tension of the diaphragm spring 10 in any case owing to the tolerances during production of pressure plate unit 3 and clutch disc 4. This allows the remaining axial path of the clutch housing 9 towards the flywheel 2 to be established in order to arrive at the necessary initial tension. In the present case, the striking distance Y between the contact face 12 of the fastening flange 18 and the offset face 14 on the flywheel 2 will be present after the contact faces 11 and 12 have made contact with one another. In this position of the clutch housing 9, the fastening screws 19 are inserted and the pressure plate unit 3 is screwed rigidly to the flywheel 2. A sufficiently great axial force is then exerted by means of the former 16 plastically to deform the clutch housing 9 in the axial direction until, after covering the deformation path X, it assumes its prescribed position and the diaphragm spring 10 has the necessary initial tension. For this purpose, the former 16 has a projection 20 of which the external diameter coincides with the transition from the shoulder 21 of the flywheel 2 into the offset face 14. The plastic deformation of the clutch housing 9 therefore takes place exactly in a predetermined diameter range radially inside the fastening screws 19 and can therefore be carried out without affecting the shape of the remainder of the clutch housing. The illustration in Figure 1 shows the state after plastic 8 deformation. The former 16 is then removed and the friction clutch 1 is screwed on the carrier disc 6.

Figure 2 shows a variation in a partial view in which the clutch housing 9 has, radially inside the fastening flange 18, a substantially cylindrically extending region provided with an encircling, substantially V-shaped groove 15 which is subjected to plastic deformation. In the present case, a former 16 substantially corresponding to Figure 1 is used which is applied from the exterior onto the clutch housing 9 and, by the methods already described - on the basis of the striking distance Y covers the deformation path X in the direction of the arrow toward the flywheel 2.

Figure 3 shows a detail of a variation of Figures 1 and 2. The fastening flange 18 of the clutch housing 9 is partially provided with partial faces 22 which extend concentrically round the openings for fastening screws 19 and project relative to the face of the fastening flange 18 toward the flywheel 2. A region w ' ith corresponding recesses, which serve as a support face for the heads of the fastening screws 19, is located in an equal diameter and substantially at the same axial distance on the rear of the fastening flange 18. In this case, the plastic deformation is produced by a plurality of formers 17 which are arranged on the periphery, are constructed annularly, surround the heads of the fastening screws 19 and of which the internal diameter corresponds to the external diameter of the partial faces 22. By the arrangement of individual regions, distributed round the periphery, for plastic deformation according to the deformation path X it is possible to eliminate repercussions on the shape of the clutch housing 9 during the plastic deformation.

Figure 4 again shows - on an enlarged scale - the design according to Figure 3 during construction of the friction 9 clutch. As in Figures 2 and 3, the components such as clutch disc, pressing plate and diaphragm spring arranged between clutch housing 9 and flywheel 2 are omitted for the sake of clarity. The situation illustrated shows the position on reaching the residual path Z just before the contact faces 11 and 22 strike one another. In this state, the clutch housing 9 has already been loaded by a considerable force in the direction of the arrow and the clutch main spring is partially prestressed. With knowledge of the initial tension of the clutch main spring attained hitherto and by measuring out the residual path Z it is known how great the deformation path X following the coverage of the residual path Z must be in order to achieve the functional initial tension of the clutch main spring. After measuring the initial spring tension in the illustrated position and the residual path Z, the clutch housing is screwed on the flywheel 2 by the fastening screw 19 and the plastic deformation is then produced via the former 17. This procedure is identical to that shown in Figure 3.

The described process, when suitably carried out, allows the tolerances occurring during production of pressure plate and clutch disc subsequently to be eliminated and allows the fitted position of the clutch main spring to be adjusted exactly.

Claims

CLAIMS:

e) 1. A method of assembling a friction clutch assembly which has a flywheel (2) on an axis of rotation (7), a clutch housing (9) fastened on the flywheel (2), a pressing plate (8) guided non-rotatably but axially movably on the clutch housing (9), a clutch disc (4) arranged with its friction linings axially between the flywheel (2) and the pressing plate (8) and a clutch main spring arrangement (10) tensioning the pressing plate (8) via the friction linings against the flywheel (2), wherein the clutch main spring arrangement (10) has a predetermined pressing force/spring travel characteristic and, when the friction clutch is engaged, is prestressed to a predetermined pressing force value, comprising the process steps a) pre-assembly of the clutch housing (9), the pressing plate (8) and the clutch main spring arrangement (10) to form a pressure plate unit (3); b) application of the pressure plate unit (3) onto the flywheel (2) with interposition of the clutch disc (4); c) fastening of the clutch housing (9) on the flywheel (2), characterised by the following process steps for assembly of a friction clutch, in which the axial tolerances of the pressure plate unit (3), the clutch disc (4) and the flywheel (2) are adapted to one another such that process step (c) leads to a pressing force of the clutch main spring arrangement (10) which is lower than the predetermined pressing force value: d) measurement of the pressing force of the clutch main spring arrangement (10) while the pressure plate unit (3) is moved against the force of the clutch main spring arrangement (10) into a predetermined axial position relative to the flywheel (2) in step b); determination of the axial residual path over which the pressure plate unit (3) is to move based on the predetermined axial position relative to the flywheel when the clutch main spring arrangement (10) is to be prestressed to the predetermined pressing force value, more specifically as a function of the predetermined pressing force/spring travel characteristic; and f) axial shifting of the clutch housing (9) fastened on the flywheel (2) in step c) with plastic deformation of the clutch housing (9) by the residual path determined in step e) relative to the flywheel (2).
2. A method as claimed in claim 1, wherein the predetermined axial position of the pressure plate unit is the position in which the clutch housing (9) rests almost or completely on the flywheel (2).
3. A method as claimed in claim I or 2, wherein the clutch housing (9) is plastically deformed in step f) in the region of a radially projecting fastening flange (18) fastened on the flywheel (2) in step c) or in the region (15) of axially extending peripheral walls.
4. A method as claimed in claim 3, wherein, in step f), the flywheel (2) is axially supported and the clutch housing (9) is pressed toward the flywheel (2) by a former (16, 17) applied axially to the fastening flange (18) or to the region of the peripheral wall remote from the flywheel (2).
5. A friction clutch assembly for assembling by the method as claimed in any one of claims 1 to 4, in which the clutch housing (9) has a substantially axially extending peripheral wall from which a fastening flange (18) resting on the flywheel (2) projects radially, wherein the peripheral wall has, in particular, a substantially V-shaped encircling groove (15).
6. A friction clutch assembly for assembling by the method as claimed in any one of claims 1 to 4, in which the clutch housing (9) has a substantially axially extending peripheral wall from which a fastening flange (18) projects radially outwardly, the fastening flange (18) resting on a contact face (11) of the flywheel (2) and being fastened on the contact face (11) by screws (19), wherein the contact face (11) of the flywheel (2) forms, radially inside the region of arrangement of the fastening screws (19), a recess (14) which overlaps a region of action of the fastening flange, located radially between the fastening screws (19) and the peripheral wall, for a former (16).
7. A friction clutch assembly for assembly by the method as claimed in any one of claims 1 to 4, in which the clutch housing (9) rests with a radially projecting fastening flange (18) on a contact face (11) of the flywheel (2) and the fastening flange (18) is fastened on the contact face (11) by screws ( 19), wherein the fastening flange (18) rests, with contact regions (22) substantially circularly concentrically surrounding the screws (19), on the contact face 11 of the flywheel (2), the contact regions (22) being curved from the fastening flange (18) towards the flywheel (2).
8. A method of assembling a friction clutch assembly substantially as described with reference to Figure 1, Figure 2, or Figures 3 and 4, of the accompanying drawings.