GB2332487A

GB2332487A - Friction clutch with rivet head clearance recesses

Info

Publication number: GB2332487A
Application number: GB9904792A
Authority: GB
Inventors: Jurgen Kleifges; Bernhard Schierling; Harald Jeppe
Original assignee: Mannesmann Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1995-04-21
Filing date: 1996-04-16
Publication date: 1999-06-23
Anticipated expiration: 2016-04-16
Also published as: GB2332488A; GB9904796D0; GB2332487B; GB9904792D0; GB2332488B

Abstract

A friction clutch comprises a sheet metal support carrier 13 having on each side a friction lining ring 16 which has a substantially uniform thickness and is fixed to the support carrier 13 by rivets 21. The lining rings 16 are radially extended to a region radially inside the zone of frictional surfaces 4, 7 and are rivetted to the support carrier 13 in this region. Frictional surfaces 4, 7, in this region, are provided with recesses 26, 27 having inclined obtuse angled surfaces which afford clearance to rivet heads as the lining rings wear, thus assuring a trouble free release operation of the clutch. Friction surface 4 is on a flywheel mass 2 secured to a crankshaft of an engine and friction surface 7 is on a pressing plate 6 loaded by diaphragm spring 8 towards mass 2. Support carrier 13 is rotationally fixed, eg via a torsional damper 12, to a hub and plate 6 is torsionally fixed but axially moveable with respect to a casing 5. The lining rings 16 may possess circumferentially offset recesses so as to vary where the rivet heads bear (see fig 4).

Description

1 Friction clutch for an automobile This invention relates to a friction

clutch for an automobile.

A known form of friction clutch has ffiction ring 2332487 interposed between frictional surfaces of a flywheel mass and a pressing plate urged by a spring towards the flywheel mass.

A friction clutch of this type is known, for example, from DE OS 2-33 02 808. In this construction, two friction lining rings are provided, which are riveted to a support, in the region of the friction faces of flywheel and pressing plate. Such a form of construction ensures that the friction lining rings can only be worn down until the ffiction surface of ly the pressing plate and the flywheel respectively come into contact acrainst the heads of the rivets. The remainder of the friction lining rings must be discarded unused. This leads to high costs, because the friction lining rings amount to a large part of the total cost of the clutch disc.

It is the objective of the present invention to construct a clutch disc with riveted-on friction lining rings such that the largest possible volume is available for wear and the remaining volume after the normal life is as small as possible.

According to the invention there is provided a friction clutch for an automobile, W comprising a flywheel mass for connection to the crankshaft of an interrial combustion engine and having an annular friction surface, a clutch easing fixed to the flywheel mass, a pressing plate mounted torsionally locked in the clutch easing but axially displaceable, havino, an annular friction surface substantially in axial alignment With the friction surface of the flywheel mass, a clutch spring for applying an axial force to the pressing plate 2 towards the flywheel mass and a clutch disc having ffiction lining rings interposed between the pressing plate and the flywheel mass, the clutch disc being torsionally keyed to a hub, wherein the clutch disc takes the form of a support carrier which is torsionally keyed to the hub, the support carrier extending from the hub radially outwards into the region of the friction surfaces and comprising on each side one of the friction lining rin s 9 with correspondincr counter-friction surfaces confronting the friction surfaces of the pressing plate and flywheel mass, wherein the two friction lining rings possess a substantially uniform thickness of material over their radial extent and extend at least in one radial direction beyond the ftiction surfaces and are riveted in this region to the support carrier wherein the pressing plate and the flywheel mass possess recesses in the region in which the friction linin(:),, rings pr ject radially beyond the ffiction surfaces, and -7 01 the recesses lead via inclined surfaces at obtuse angles into the friction surfaces.

1:1 By the displacement of the fixing regions in the radial direction out of the ffiction areas, c) it is possible to provide the friction lining rings easily with such a tl- ckness of material that this thickness is, if at all, only slightly greater than the admissible wear. In this way the mass moment of inertia of the clutch can be considerably reduced because the ffiction lininQs have the --Teatest distance from the axis of rotation. Furthermore, the production of the clutch disc can be made considerably cheaper, because the friction lining rings are simple to manufacture and have a relatively small volume. In addition, the counterfriction surfaces of the friction lining rings are made without interT-uptions over their entire effective area. which is to the benefit both of stability and also the volume of wear.

BY, the arrangement of recesses at the pressing plate and at the flywheel mass, in the re21on in which the friction lining rings extend radially beyond the friction surfaces and 3 having the recesses lead via inclined surfaces at obtuse angles in to the friction surfaces, the invention provides the ability to maintain the operational reliability of the friction clutch especially in respect of satisfactory clutch release, even with increasing wear of the friction linings.

The edges in the region of the transition ftorn the inclined surfaces to the friction surface may be chamfered. This measure reduces, in an especially simple manner, a notch effect between the partly worn region of the friction lining g ring and the region not subject to Z:1 wear.

The invention is explained in more detail below with reference to various embodiments, In the drawings Fig. I is a longitudinal section through the upper half of a friction clutch constructed in accordance with the invention, Fig. 2 is a partial section through worn friction lining rings corresponding to 1 - Fia. 1 - Fig. 3 is a partial section through axially sprung apart friction lining rings., Fig. 4 is a partial section of a friction lining ring with radially inwardly open fixing openings; Flaures 5 and 6 are views of two different supports in the form of lining springs and z:t 4 Figures 7 to 9 are partial views of different friction lining rings.

Fig- I shows the basic construction of a friction clutch 1. This consists of a flywheel mass 2, which in the present case is secured by a disc 3 to a crankshaft, not shown, of an internal combustion en(21ne. It Will be self-evident that the flywheel mass 2 can be connected, in a manner not further described, via a torsion damping device to a further flywheel mass, which is secured directly to the crank-shaft. On the flywheel mass 2, a clutch casing 5 is fixed. The casing 5 houses a pressing plate 6, which is connected in axially displaceable but torsionally keyed manner to the clutch casin- 5, e.(),. via 1:1 'D tangential leaf springs. The clutch casing 5 furthermore contains a membrane spring 8, t which on the one hand is supported via spacer pins 9 against the clutch casing 5 and on the other hand bears against the pressing plate 6 and loads the latter with a force towards the flywheel mass 2. The pressing plate 6 and the flywheel mass 2 are provided with annular friction surfaces 4, 7 respectively, which basically are axially aligned with each other. Between the pressing plate 6 and the flywheel mass 2, friction lining rings 16 of a clutch disc 10 can be clamped. The clutch disc 10 possesses a torsionally keyed connection between the friction lining rings 16 and the hub, which is mounted torsionally keyed on a gear shaft, not shown. This torsionally keyed connection includes, in the present case, a support 13. Between the support 13 and the hub I I a ftirther torsion damper 12 is provided. The support I') is connected, in its radially inner zone, with a component of the torsion damper 12, or this component of the torsion damper 12 is extended radially outwards sufficiently far for it to be able to fulfill the function of the support 13. In the present case, the support 13 extends radially outwards sufficiently far to coincide substantially with the external diameters of the friction lining rings 16. Both the friction lining rings 16 have counter-friction surfaces 4', 7' respectively, which correspond to the friction surfaces 4 of the flywheel mass 2 and the friction surface 7 of the pressing plate 6 respectively. The friction lining rings 16 are lengthened radially inwards beyond the counter-friction surfaces 4' and 7' respectively and in this region the friction lining rings 16 are riveted to the support 13. For this purpose, the support 133 possesses rivet openings 25, which correspond to fixing openings in the friction lining rings. In this connection, reference should be made to Fig. 4, which shows a half-view of a friction lining ring 16, which extends radially inwards beyond the counter-friction surfaces 4' and 7' respectively and possesses there radially inwardly open fixing openings 23. Circumferentialy offset from these fixing, openings 23, recesses 24 are provided. These serve, on the one hand, for lightening the weight of the friction lin-ing ring 16 and, on the other hand, afford the possibility that two identical friction lining nings 16 can be brou-ht into overlap with one another by rotation so that each fixing opening 2') =1 In corresponds to a recess 24. This makes riveting according to Fig. I possible, At each I fixing point, a rivet 20 is passed with its shank through the fixing opening 23 in the tD I I friction lirung ring 16, so that its set head 21 comes to bear against the outer face of the friction lining ring. The shank also passes through the rivet operung 25 in the support 13 and is riveted on the face of the support 0 remote from the firiction lirling ring 16. The closing head 22 of the rivet 20 is thus located in the recess 24 of the opposite friction lirUng ring 16.

From Fig. 1 it can also be seen that, in the region of the fixing openings 23 and recesses C:1 24 respectively of the friction lining rings 16, the pressing plate 6 is provided with a 0 C recess 26 and the fl,,,wheel mass 2 with a recess 27. These recesses 26, 27 terminate in an inclined surface with an obtuse angle a running into the friction surface 4, 7 respectively.

6 In connection with Fig. 2, which shows a worn friction clutch 1, it can be seen that with W f the friction linin 1 increasing wear o g rings 16, a step develops in the latter, which corresponds to the inclined surface of the recesses 26 and 27. By this form of construction, even after wear has occurred, a trouble-free release operation for the clutch disc 10 is assured, because there is no cylindrical step against which the pressing plate 6 can catch or against which the clutch disc can catch on the flywheel mass 2. Preferably, the inclined surfaces in the pressing plate 6 and flywheel mass 2 are interrupted or 1:1 chamfered at the transition into the friction surfaces 4, 7 respectively, so that there are no sharp edges here. By this construction it is possible to wear down the ffiction lining rings 16 in the region of their counter-friction surfaces 4' and 7 virtually as far as the support 13. The fixing reClions between the friction lining rings 16 and the support 1-33 W Z= are thus unaffected by the wear.

Figures 5 and 6 each show a lining spring 14, 15 respectively, which may be used instead of the support I') as a carrier for the friction li ing rings 16. The lining spring 14 1 I ini 1. n is provided with a web 29, extending substantially radially inwards, which leads radially inwards into a foot 28. By this foot 28, the lining spring 14 is connected either directly to the hub I I or to a component of the torsion damper 12. Radially outwards, the web 29 is adjoined in each circumferential direction by a fin 30, 31 respectively, these fins 30, 31 corresponding in the axial direction substantially with the friction surfaces 4, 7 respectively or the counter-friction surfaces 4', 7' respectively. The fins 3) 0, 3 1 are each formed undulating in the circumferential direction in order to make possible an axial springing action of the two friction lining rings 16 against one another. In the present case, a tongue 32 extends radially inwards out of the fin 3)1 and comprises a rivet hole 33. A further rivet hole 33 is disposed in the web 29- It is, however, readily also possible to provide, on the fin 30, a tongue 32', which is provided either instead of the 7 rivet hole 3 ') in the web 29 or additionally thereto. Several lining springs 14 are fixed alternating with one another in the circumferential direction, and the two friction lining rings 16 are riveted to the one or the other lining spring, alternately from both sides c 1 analogously to Fig. 1.

spring 15, which is intended for double-sided ar angement. In such Fig. 6 shows a lining cn I T = an arrangement, two lining springs 15 are installed opposite handed to each other, different openings being provided in the radially inwardly extending tongues 332, which project from the fins 30, 3 1. In the one tongue 32, a rivet hole 33) is provided, and in the other tongue 32 an opening '34, these two openings being explained in connection with Fig. 3. Fig. 3) shows a section through the two friction lining rings 16, which are installed in conjunction with the lining springs 15. The lining springs 15 are shown here in the outwardly sprung state corresponding to the released friction clutch 1. The maximum release travel of the two friction lining rings 16 is determined by the corresponding stepped rivets 336. These are so constructed that they have two different shank diameters. The stepped rivet 36 passes, with its smaller shank diameter, through the fiXing opening 23 of the friction lining ring 16 according to Fig. 4 and also through the rivet hole 33 in the one lining spring 15. Adjoining this, the rivet shank is provided with a laraer diameter, so that this one lining spring 15 can be firmly riveted to the corresponding friction lining ring 16. The stepped rivet 36 passes, with its larger shank diameter, through the opening 34 in the other tongue 32 of the other lining spring 15 and 11:1 engages behind this tongue 32 with its other rivet head. In this way, on the one hand, a determined prestress between the two lining springs 15 can be achieved and, on the other hand, a linutation to the outward springing in the disengaged state of the friction clutch.

8 Figures 7 to 9 show different forms of construction of the friction lining rings. Thus, for example, the ffiction lirung ring 17 according to Fig. 7 is so shaped that the fixing openings 35 and the recesses 24 extend radially outwards beyond the count er-fi-i ction surfaces 4' and 7' respectively. With such an attachment of the friction lining rings 17, a ZD ZD better transfer of torque into the support carrier is possible, because a larger diameter is available here.

According to Fig. 8, the friction lining ring 18 is so formed that both radially outside and also radially inside the count er-friction surfaces 4', 7' respectively, fixing opening 35 and recesses 24 are provided. In a case of this type, a doubled attachment can be provided, which may be advantageous especially in the case of exceptionally high torques.

In Fig. 9, a friction lining ring 19 is illustrated, which possesses its fixing openings 35 1:1 -ty Z radially outside the counter-ffiction surfaces 4', T respectively and which is constructed in its external diameter without interruption all around. For this purpose, apertures or recesses 37 are provided circumferentially offset from the individual fixing opening 35, these apertures or recesses fulfilling the function of the recesses 24. Such a form of a that is construction provides also the better torque transfer and also a friction lining rin.' especially simple to manufacture.

Reference is directed to UK patent application 9607828.2 "the parent application" which contains subject matter common to this application, The parent application has a claim defining a friction clutch in the following terms.

A friction clutch for an automobile, comprising a flywheel mass for connection to the crankshaft of an internal combustion engine and having, an annular friction surface. a 9 clutch casing fixed to the flywheel mass, a pressing plate mounted torsionally locked in D the clutch casing but axially displaceable, having an annular ffiction surface substantially in axial alignment w-ith the fTiction surface of the flywheel mass, a clutch spring for applying an axial force to the pressing plate towards the flywheel mass and a clutch disc ha-,,,In(y friction lining rings interposed between the pressing plate and the flywheel mass, the clutch disc being torsionally keyed to a hub-, wherein the clutch disc takes the form of a support carrier which is torsionally keyed to the hub, the support carrier extending ID from the hub radially outwards into the region of the ffiction surfaces and comprising on I each side one of the friction lining rings With corresponding counter- friction surfaces Z) V confronting the friction surfaces of the pressing plate and flywheel mass, wherein the two friction lining rings possess a substantially uniform thickness of material over their radial ID extent and extend at least in one radial direction beyond the friction surfaces and are riveted in this region to the support carrier, wherein the support carrier consists of individual lining springs distributed around the circumference, which possess fins orientated alon- the circumference inside the friction surfaces and also substantially radially orientated webs, which make the connection to the hub or to a torsion damper and wherein rivet holes are provided at least in tongues pr jecting radially out of the fins, OJ 1 -1 1 these tongues extending radially outside the friction surfaces.

C.

Reference is also directed to UK patent application "the second divisional application" which also contains subject matter common to this application. The second divisional application has a claim defining a friction clutch in the following ternis.

A friction clutch for an automobile, comprising a flywheel mass for connection to the crankshaft of an internal combustion engine and having an annular friction surface, a clutch casing fixed to the flywheel mass, a pressing plate mounted torsionally locked in the clutch casing but axially displaceable, having an annular ffiction surface substantially in axial alignment with the friction surface of the flywheel mass, a clutch spring for applying an axial force to the pressing plate towards the flywheel mass and a clutch disc having friction lining rings interposed between the pressing, plate and the flywheel mass, the clutch disc being torsionally keyed to a hub; wherein the clutch disc takes the form of a support carrier which is torsionally keyed to the hub, the support carrier extending from the hub radially outwards into the region of the friction surfaces and comprising on each side one of the friction lining rings with corresponding counter- friction surfaces confronting the ffiction surfaces of the pressing plate and flywheel mass, wherein the two ftiction lining rings possess a substantially uniform thickness of material over their radial extent and extend at least in one radial direction beyond the friction surfaces and are riveted in this region to the support carrier and wherein the support carrier is formed as a plane sheet metal component with friction lining rings disposed on both sides and rivets corinect the one and the other ffiction lining ring respectively to the support carrier radially inside and/or radially outside the projections of the friction surfaces.

11

Claims

Claims

I. A friction clutch for an automobile, comprising a flywheel mass for connection to the crankshaft of an internal combustion engine and having an annular friction surface. a clutch casing ly , fixed to the flywheel mass, a pressing plate mounted torsional locked in the clutch casing but axially displaceable, having an annular friction surface substantially in axial alignment with the friction surface of the flywheel mass, a clutch spnina for applying an axial force to the pressing plate towards the flywheel mass and a clutch disc having friction lining rings interposed between the pressing plate and the flywheel mass, In C the clutch disc being torsionally keyed to a hub; wherein the clutch disc takes the form of a support camer which is torsionally keyed to the hub, the support carrier extendin!a from the hub radially outwards into the region of the friction surfaces and compnsincr on each side one of the ffiction. lining rings with corresponding counter-friction surfaces confronting the friction surfaces of the pressing plate and flywheel mass, wherein the two friction lining rings possess a substantially uniform thickness of material over their radial extent and extend at least in one radial direction beyond the friction surfaces and are riveted in this region to the support carrier wherein the pressing plate and the flywheel mass possess recesses in the region in which the friction lining rings pr ject radially lt I= 01 beyond the friction surfaces, and the recesses lead via inclined surfaces at obtuse angles into the friction surfaces.
2. A friction clutch according to claim 1, wherein the edges in the region of the 1 - transition from the inclined surfaces to the friction surface are chamfered.