GB2234323A

GB2234323A - Friction clutch driven plates

Info

Publication number: GB2234323A
Application number: GB8916766A
Authority: GB
Inventors: Anthony John Curtis
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1989-07-21
Filing date: 1989-07-21
Publication date: 1991-01-30
Anticipated expiration: 2009-07-21
Also published as: GB2234323B; GB8916766D0

Abstract

A friction clutch driven plate having a friction facing carrier (14) mounted on a hub (11) with torsion damping springs (15, 48) operating in two stages to resist rotation of the carrier (14) around the hub (11). A friction damper (52, 42) operates during the initial damping phase together with first stage torsion damping springs (48). The friction damper comprises a flange plate (43) rotationally fast with the hub(11), a pair of side plates (41, 42) fast with the carrier (14) and located on each side of the flange plate (43), and a friction plate (52) located between the flange plate (43) and one of the side plates (42). The friction plate (52) is free to rotate relative to the other plates (41, 42, 43) and is biased into frictional engagement with the side plate (42) to generate the friction damping. The plates (41, 42, 43) also house the springs (48) and form part of the first stage torsion damping means. <IMAGE>

Description

FRICTION CLUTCH DRIVEN PLATES This invention relates to friction clutch driven plates, and in particular, but not exclusively, to friction clutch driven plates for use on vehicles.

In a typical motor vehicle the engine is connected to the vehicle gearbox via a friction clutch which includes a fly wheel and pressure plate connected to the engine, and between which is sandwiched a driven plate which is connected to the gearbox.

A friction clutch driven plate typically comprises a hub which is splined onto the gearbox input shaft, a co-axial friction facing carrier plate mounted on the hub and capable of limited angular rotation about the hub, and springs housed in aligned apertures in a flange connected to the hub and the carrier plate, to act between the hub and carrier plate to restrain said angular rotation. The facing carrier plate is connected to the vehicle flywheel through the friction facings.

In some vehicles when the engine is idling and there is no torque load passing through the clutch driven plate the irregular impulses from the vehicle engine can be transmitted to the gearbox and cause gearbox idle chatter.

Solutions to overcome this problem have involved the use of multi-stage spring damping in which the movement between the friction facing carrier plate and the hub flange is dampened by main or second stage damping springs and the hub flange is free to rotate through a limited angular movement relative to the hub drive and is restrained in this movement by a very low rate first stage torsional damping spring or springs. The hub flange can oscillate around the hub when the vehicle is idling with only the first stage damping springs operating to suppress any transmission of vibrations to the gearbox.

These very low load impulses passing through the driven plate can also be dampened by use of a low rate friction damping means which is operated sometimes in conjunction with the first stage damping.

The present invention provides a low rate friction damping means for use in a friction clutch driven plate having at least two stages of torsion damping operational between the friction facing carrier and the hub.

Accordingly there is provided a friction clutch driven plate comprising a hub, a friction facing carrier mounted on the hub and capable of limited angular movement around the hub, torsion damping means acting between the facing carrier and the hub to resist said rotational movement, said torsion damping means comprising a first stage torsion damping means operable over an initial phase of said annular rotation, main torsion damping means operable over a second phase of said angular rotation, and a friction damping means operable between the carrier and the hub for said initial phase, said friction damping means comprising a flange plate rotationally fast with one of the hub and facing carrier, a pair of side plates arranged one on each side of the flange plate and which are rotationally fast with each other and with the other of the facing carrier and hub, and a friction plate located between the flange plate and one of said side plates and which is capable of limited angular rotation relative to both the flange plate and the side plates, said friction plate being axially moveable relative to the flange and side plates and being biased into frictional engagement with said one side plate to generate friction damping during said initial phase.

Conveniently saia friction damping means flange plate is rotationally fast with the hub and the side plates are made rotationally fast with the carrier.

Preferably said friction damping means flange plate comprises two plates arranged side by side and which are rotationally fast with the hub and which are axially moveable relative to each other.

Convienently in the friction damping means there are two friction plates each of which is located between said flange plate and a respective side plate, and a spring washer acts between the two friction plates to bias each friction plate into frictional engagement with the adjacent side plate.

The invention will now be described by way of example and with reference to the accompanying drawings in which: FIG 1 is an elevation of a clutch driven plate according to the invention, FIG 1A is a sectional view showing the hub flange meshing with the hub splines, FIG 2 is G section on the line II-II showing the central portion only Fig. 1, FIG 3 is a section similar to Fig 2 showing an alternative construction for the friction damping means, FIG 4 is a similar section to Fig 2 showing yet another alternative friction damping means, FIG 5 and Fig 6 show side plates from the friction damping means viewed from one side, FIG 7 is a friction plate from the friction damping means viewed from one side, FIG 8 is the centre flange plate of the friction damping means, FIG 9 is a elevation from view A showing the assembled friction damping means with one side plate removed to show the assembly, FIG 10 is a graph of torsion load versus angular displacement for a driven plate according to this invention.

With reference to Figs 1 1A and Fig. 2 there is illustratged a friction clutch driven plate for a motor vehicle and which comprises a hub 11 having internal splines 13 for connection with a gearbox input shaft and an annular array of circumferentiaily spaced teeth 20 extending radially outwards on the outer surface of the hub 11. A coaxial annular flange 12 having spaced annular notches 30 in its inner peripheral margin is mounted on the hub 11 concentrically with the teeth 20 so that the teeth 20 loosely engage with the notches 30 allowing the flange 12 limited angular movement about the hub 11. A coaxial friction facing carrier 14 is also mounted on the hub 11 and is capable of limited angular movement relative to both the flange 12 and the hub 11.

A set of main torsion damping springs 15 are housed in aligned apertures 16 and 17 in the hub flange 12 and facing carrier 14 respectively, and act to restrain the angular movement therebetween. Although the number of springs illustrated is a preferred six springs, there is no reason why other number of springs cannot be used,forexample between four springs and eight springs.

The annular facing carrier 14 comprises an annular carrier plate 18 located to one axial side of the flange 12, and an annular retainer plate 19 disposed on the other axial side of the flange 12. The two annular plates 18 and 19 are secured together by three stop pins 21 which pass through co-operating apertures in the outer peripheral margin of the flange 12. The stop pins 21 limit the rotational movement of the facing carrier 14 about the hub 11 and flange 12 by abutment against the radial ends of the apertures.

A plurality of segments 23 are arranged in a circular array and are attached to the outer peripheral margin of the carrier plate 18 by any suitable means such as rivets, and a pair of opposed annular friction facings 24 are secured one on each side of the segments 23 by suitable means such as rivets. The segments 23 typically are of spring steel and are shaped to provide resilient axial cushioning between the two friction facings.

A friction damping washer 26 is located axially between the hub flange 12 and the carrier plate 18 and the carrier plate 18 is biased against the friction washer 26 by a spring washer 28 located between the hub flange 12 and the side plate 41 of a first stage damping means 50 to be described later.

The main damping springs 15 are housed in the aligned apertures (sometimes referred to as spring windows) 16, in the hub flange 12, and apertures 17 in the carrier plate 18 and retainer plate 19. The spring windows 16 and 17 have circumferential ends that are contactable with the ends of the springs 15 during the rotational movement of the carrier 14 around the hub 11 to compress the springs 15. The main damping springs may all act simultanously or can be brought into operation after different angular phases of rotation, as is well known in the trade.

The teeth 20 on the hub 11 are engaged in the notches 30 on the inner peripheral margin of flange 12 so that the flange 12 is capable of limited angular rotation around the hub 11. The angular rotation of the flange 12 around the hub 11 being limited in both directions of rotation by abutment of teeth 20 with the circumferential ends of the notches 30.

The rotational movement between the flange 12 and the hub 11 is resisted by a first stage damper means.

The first stage damping means 50 is of a similar construction to the main damping unit of the driven plate and comprises a flange plate 43 and a pair of side plates 41, and 42. The flange plate 43 has lugs 44 on its inner periphery for engagement with splines or slots 45 on the outer surface of the hub 11 so that the flange plate is rotationally fast with the hub 11 and is free to move axially, this is more easily seen in Fig. 8. The side plates 41 and 42 are fastened together by pins 46, preferably four pins which pass through elongated apertures 51 in the flange plate 43 so that the side plates 41 and 42 are free to rotate relative to the flange plate 43. The side plates 41 and 42 are made rotationally fast to the hub flange 12 by three axial tabs 47 on the plate 41 that engage in slots on the radially inner edge of the hub flange spring windows 16.

An annular friction plate 52 is located axially between the flange plate 43 and the axially outer side plate 42.

The friction plate 52 is shown in Fig 7 and has lugs 53 on its inner periphery that loosely engage the slots 45 on the outer surface of the hub 11. The lugs 53 are a loose fit in the splines to allow the friction plate 52 to move rotationally relative to the flange plate 43.

The friction plate 52 has apertures 49 therein to accommodate the pins 46 when the plate 52 rotates relative to the flange plate 43.

Four first stage torsion damping springs 48 are housed in spring apertures or windows 54, 55, 56, in the flange plate 43 and side plates 41 and 42 respectively and friction plate 52 (see Figs 5, 6, 7, and 9). These low rate springs 48 provide a resistance to rotation which is much less than for the main torsion damping springs.

The springs 48 may all have the same spring rating or not as is desired and can all be brought into operation simultaneously or may be phased in at different dwell angles, again as is desired. In this case at least two springs are an exact fit in the flange plate spring windows 54, side plate windows 55, and friction plate windows 56 to return the hub 11 to an at-rest position relative to the hub flange under no-load conditions (no torque loads on the friction facings) and also to give the required torque versus angular displacement characteristics for the clutch The other two springs 48 are arranged to come on in stages by having cricumferentially elongated spring windows 54A in the flange plate 43. In this case the second pair of springs come into operation after about 7O of rotational movement.Furthermore as can be seen in Fig. 9, when the side plates 41, 42, hub flang 43, and friction plate 52 are assembled, the assembly can be arranged so that the pins 46 are off set relative to the apertures 49, and 51 in the flange plate and friction plates respectively reflecting the movement characteristics set by the relationship between the hub teeth 20 and the notches 30 in the flange 12 Similarly the lugs 53 on the inner periphery of the friction plate 52 are illustrated as being off set in the slot 45 on the hub 11 so that in the drive direction of rotation from the 'at rest' condition the friction plate 52 is free to rotate about 7O and in the other direction of the rotation is free to rotate only lo.

An alignment hole 57 is present in each side plate, 41, 42, flange plate 43 and friction plate 52 to aid correct assembly of the components.

A spring washer 58, preferably a wavy washer, is located radially outwardly and concentric with the hub flange 43 to act between the side plate 41 and the friction plate 52 to bias the friction plate 52 into frictional engagement with the other side plate 42. This spring washer is of sufficient strength to generate a hysteresis of between 6-12 Nm. A second spring washer 59 is located coaxially to the hub 11 between the teeth 20 on the outer surface of the hub and the side plate 41 and rubs against the two surfaces. This spring 59 is of sufficent strength to generate a hysteris of about 1.0 to 3.0 Nm so it can be seen that the spring 58 is a much stronger spring than the spring 59.

The operation of the driven plate will now be explained also with reference to Fig. 1 and Fig 10 and with the hub 11 held stationary and a drive load applied to the friction facings 24, the facing carrier 14 is moved anti-clockwise as shown by arrow X in Fig. 1. Since carrier 14 and flange 12 are held rotationaly fast by the main torsion damping springs 15, the flange 12 will initially move with the carrier 14 relative to the hub 11 to take up the clearance 'L' between the teeth 20 and notches 30. Since the plates 41 and 42 are held fast in the hub flange 12, by the tab 47 and the friction damper flange plate 43 is held fast to the hub 11, and because spring 58 is stronger than the spring 59, the friction plate 52 is held stationary relative to the side plates 41 & 42 and the initial resistance to rotational movement is due to the friction damping generated by the spring 59 rubbing on either the side plate 41 or the side of the teeth 20, and also biasing the carrier plate 18 so that it also rubs on the side of the teeth 20, and by the first stage damping springs 48. In the initial phase only two springs 48 are compressed between the ends of the spring windows 55 and 54.

This is the stage A of the graph in Fig 10. After the lost motion clearance 'M' the lugs 53 on the friction plate 52 and slots 45 on the hub 11 has been taken up (see Fig. 9), the friction plate 52 is now held stationary relative to the flange plate 43, and the second pair of first stage damping springs 48 in the hub flange apertures 54A also begin to operate being compresed between the ends of the side plate windows 55 and the hub flange windows 54. Since the friction plate 52 is now held stationary, further movement of the facing carrier 14 is resisted by fricton damping generated between the friction plate 52 and the side plate 42, and by all four first stage damping springs 48. this is the stage B in Fig 10. the friction hysteris during this stage B is higher than during the initial stage C.

This stage B continues until the lost-motion clearance 'L' between the hub flange 12, and the hub 11, is taken up (see Fig lA.) and should be for about 2O of relative rotation. This effectively this ends the operation of the first stage damper.

When the lost motion movement between the teeth 20 on the hub 11 and the notches in the hub flange 12 has been taken up, further anti-clockwise movement causes the compression of the main torsion springs 15 between the end of the respective flange spring windows 16 and the opposed friction carried spring windows 17. As the carrier 14 rotates around the hub 11 and flange 12 some friction hysterises will be generated by the friction washers 26 under the bias of the spring washers 28 & 59 The friction facing continues its relative clockwise movement until the stop pins 21 abut the ends of the stop pins apertures as is well known in the trade. This is stage C. During this stage it can be seen that the main torsion springs 15 come into operation in stages.

If the load on the facings 24 is now relieved the facing carrier now moves clockwise and the torsion loads return back down the curve, allowing for the effects of hysteresis. For the sake of simplicity the hysteresis effect has been shown only on the drive side of the graph.

When the driven plate goes into the over-run mode, with the friction facing carrier now moving clockwise relative to the hub, the clearance between the lugs 53 on the friction plate 52 and slots 45 in the clockwise direction are only about lo and therefore, initially the friction plate 52 is held stationary with the side plate 43 for only lo, and the resistance to rotation during this phase is produced by a pair of first stage damping springs 48 in the flange plate apertures 54, and by the friction damping operating between the side plate 41 and the flange plate 43. This is stage X of the graph in Fig.

10.

When the lugs 53 on the friction plate 52 are in abutment with the ends of the slots 45, the second pair of first stage springs 48 in the flange plate windows 54A also come into operation together with the friction damping operating between the friction plate 52 and the side plate 42. This is the stage Y is Fig. 10.

This stage Y continues until the teeth 30 on the hub flange 12 abut the teeth 20 on the hub 11. Since the clearance 'L2' is the anticlockwise direction is less than in the clockwise direction, the main torsion damping springs 15 come into operation after only a total rotation movement of about 3O in the over-run condition.

Further clockwise movement is resisted by the main torsion damping springs 15 and previously described.

This is stage Z of the graph.

Now with reference to Fig. 3 there is illustrated a section through a clutch driven plate which is a modification of the plate previously described and therefore the same reference numbers will be used as for the embodiment in Figs 1 and 2.

The principal modification in Fig 2 is that in the first stage damper means 50 there are a pair of friction plates 152 which are each located between a respective side plate 41, 42 and the flange plate 43. These friction plates 152 are substantially identical to the friction plate 52 of Fig 2, but are axially thinner. The spring washer 58 located radially outwardly of the flange plate 43 acts between the friction plates 152 to bias them against the adjacent side plates. By using a pair of spaced friction plates 152 a high level of friction damping can be generated in the portions B and Y of the graph, the friction damping being between the side plates 41 and 42 and respective friction plate 152. The friction damping in the first stages A and X is generated by the spring washer 59 rubbing on the side plate 41 and the side of the teeth 20. The use of two friction plates 152 gives a more even load distribution across the first stage damper means.

In Fig 4 there is illustrated yet another embodiment of the invention in which the flange plate 43 is replaced by two flange plates 243 which are substantially identical and are axially seperable.

Claims

1. A friction clutch driven plate comprising a hub, a friction facing carrier mounted on the hub and capable of limited angular movement around the hub, torsion damping means acting between the facing carrier and the hub to resist said angular movement, said torsion damping means comprision a first stage torsion damping means operable over an initial phase of said angular rotation, main torsion damping means operable over a second phase of said angular rotation, and a friction damping means operable between the carrier and the hub for said initial phase, said friction damping means comprising a flange plate rotationally fast with one of the hub and facing carrier, a pair of side plates arranged one on each side of the flange plate and which are rotationally fast with each other and with the other of the facing carrier and hub, and a friction plate located between the flange plate and one of said side plates and which is capable of limited angular rotation relative to both the flange plate and the side plates, said friction plate being axially moveable relative to the flange and side plates and -biased into frictional engagement with said one side plate to generate friction damping during said initial phase.

2. A friction clutch driven plate as claimed in Claim 1 wherein in said friction damping means, the flange plate is rotationally fast with the hub, and the side plates are made rotationally fast with the carrier.

3. A friction clutch driven plate as claimed in Claim 2, wherein in said friction damping means the side plates are connected to each other by pins which pass through co-operating aperatures in the flange plate and the friction plate, to allow limited angular movement of the side plates to both the flange plate and the friction plate.

4. A friction clutch driven plate as claimed in Claim 2 or Claim 3, wherein in said friction damping means the flange plate has lugs on its inner periphery that engage in slots in the outer periphery of the hub to hold the flange plate rotationally fast with the hub but allow for axial movement of the flange plate relative to the hub.

5. A friction clutch driven plate as claimed in Claim 4 wherein in said friction damping means the friction plate has lugs on its inner periphery that loosely engage in said slots to allow for limited angular rotation of the friction plate relative to the hub and flange plate.

6. A friction clutch driven plate as claimed in any one of Claims 1 to 5 wherein in said friction damping means, a spring washer acts between the other side plate and the friction plate to bias the friction plate into frictional engagement with said one side plate.

7. A friction clutch driven plate as claimed in Claim 6 wherein in said friction damping means, said spring washer is concentric with and radially outside of said flange plate.

8. A friction clutch driven plate as claimed in any one of Claims 1 to 7 wherein in said friction damping means, the flange plate comprises two flange plates arranged side by side and which are rotationally fast with the hub and which are axially moveable relative to each other.

9. A friction clutch driven plate as claimed in any one of Claims 1 to 5, and Claim 8 when dependant upon any one of Claims 1 to 5, wherein in said friction damping means, there are two friction plates each of which is located between said flange plate and a respective side plate, and a spring washer acts between the two friction plates to bias each friction plate into frictional engagement with the adjacent side plate.

10. A friction clutch driven plate as claimed in Claim 9 wherein in said friction damper means, the spring washer is located radially outwardly and concentric with the hub flange means.

11. A friction clutch driven plate as claimed in any one of Claims 1 to 10 wherein the side plates, flange plate and friction plate each have spring apertures therein to house springs which act between said side plates, flange plate and friction plate to resist relative rotational movement therebetween, and which form a first stage torsion damping means.

12. A friction clutch as claimed in any one of Claims 1 to 11 wherein said hub has an annular flange thereon and the friction damping means is arranged to one axial side of the annular flange with one of the two side plates adjacent the annular flange, and a spring washer acts between the hub and the adjacent friction damper side plate to bias said adjacent side plate away from the annular flange

13. A friction clutch driven plate as claimed in Claim 12 wherein said annular hub flange is capable of limited angular rotation about the hub, and the friction damping means is operated by said rotation of the annular hub flange.

14. A friction clutch driven plate as claimed in any one of claims 1 to 13 wherein in the friction damping means, said side plates, flange plate, and friction plate all have an aligment hole therein to facilitate correct assembly of the friction damping means in the driven plate.

15. A friction clutch driven plate substantially as described herein and with reference to Figs 1, 2, 5 to 10, or Fig 3, or Fig 4, the accompanying drawings.