GB2234322A

GB2234322A - Friction clutch driven plates

Info

Publication number: GB2234322A
Application number: GB8916765A
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: GB2234322B; GB8916765D0

Abstract

A rotary coupling for inclusion in a friction clutch driven plate and which comprises an annular flange means (43) with annular side plates (41, 42) arranged on each side of the flange means (43) and which are capable of notation relative to the flange means (43). The flange moans (43) comprises two flange plates (43) with a spring washer (56) located therebetween to bias them into frictional engagement with the side plates (41, 42) to form a friction damper to resist the relative rotation between the flange means and side plates. The rotary coupling is operably located in the driven plate between a hub (11) and a friction facing carrier (14) to resist an initial phase of angular movement of the carrier (14) around the hub (11). <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-carrVier-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 torsion 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 has devised a friction damping means for use in a friction clutch driven plate, and which is particularly useful in a driven plate having at least two stages of torsion damping operational between the friction facing carrier and the hub.

Accordingly there is a rotary coupling comprising a central annular flange means, and a pair of coaxial annular side plates arranged one on each side of the flange means and which are rotationally fast with each other, the side plates being capable of limited rotational movement relative to the flange means, said flange means comprising two coaxial flange plates arranged side-by-side with a spring washer located between the two flange plates to bias each plate into frictional engagement with a side plate so as to resist rotational movement between the side plates and the flange plates.

Preferably the rotary coupling forms part of a friction clutch driven plate comprising a hub, a friction facing carrier mounted on the hub and which is capable of limited angular rotation about the hub, and said rotary coupling which is operable between the facing carrier and hub to resist an initial phase of said angular rotation.

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 teeth meshing with the hub teeth, FIG 2 is a section on the line II-II of Fig. 1, FIG 3 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 illustrated 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 circumferentially spaced teeth 20 extending radially outwards on the outer surface of the hub 11. A coaxial annular flange 12. having spaced annular array of teeth 30 in its inner peripheral margin is mounted on the hub 11 concentrically with the teeth 20, so that the two sets of teeth 20 and 30 mesh and loosely engage with each other 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, for example 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 20 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.

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 mesh with the teeth 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 teeth 30.

The rotational movement between the flange 12 and the hub 11 is resisted by a rotary coupling 50 forming a part of the driven plate and which is located axially between the flange 12 and the retainer plate 19. This coupling 50 forms a first stage damping means which operates for an initial phase of rotation of the carrier 14 around the hub 11.

The first stage damping means 50 is of a similar construction to the main damping unit of the driven plate and comprises a pair of flange plates 43 and a pair of side plates 41, and 42. The flange plates 43 have lugs 44 on their inner peripheries for engagement with splines or slots 45 on the outer surface of the hub 11 so that the flange plates are rotationally fast with the hub 11 and are free to move axially. The side plates 41 and 42 are fastened together by pins 46, preferably four pins which pass through elongated apertures 51 in the flange plates 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 a washer 52 having three axial tabs 47 on its outer periphery that engage with substantially no circumferential play in slots in the radially inner edge of the flange spring windows 16, and which pass through notches 49 in the outer edge margin of the side plate 41 adjacent the flange 12.

Four first stage torsion damping springs 48 are housed in spring apertures or windows 54, 55, in the flange plates 43 and side plates 41 and 42 respectively. These low rate springs 48 provide a resistance to rotation which is much less than for the main torsion damping springs.

The tabs 47 may engage in the notches 49 in the side plate 41 with substantially no circumferential play in which case the side plates 41 and 42 move with the hub flange 12, or if desired and there is some circumferential play the operation of the damper springs 48 can be delayed until the circumferential play has been taken up.

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 c-ase at least two springs are an exact fit in the flange plate spring windows 54, and side plate windows 55, 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 circumferentially elongated spring windows in the flange plate 43.Furthermore when the side plates 41, 42, and hub plates 43, 52 are assembled, the assembly can be arranged so that the pins 46 are off set relative to the apertures 51 in the flange plates 43 so that the damping characteristics are different in the drive and overun conditions.

A first spring washer 56, preferably a wavy washer, is located between the flange plates 43 concentric with the hub 11 to act between the flange plates 43 to bias them into frictional engagement with the side plates 41 and 42. A second spring washer 57, again a wavy washer, is located coaxially to the hub 11 between the hub teeth 20 and the adjacent side plate 41 of the first stage damping meansand biases the friction damping means against the inner periphery of the carrier plate 19.

A third spring washer 58, again preferably a wavy washer, is located between the outer peripheral margin of the side plate 41 and the washer 52 to bias the washer 52 into friction engagement with the retainer plate 19, to bias the hub flange 12 against the friction washer 26, and also to bias the side plate 41 against a washer 59 located between the flange 12 and said side plate 41.

The operation of the driven plate will now be explained also with reference to Fig. 1 and Fig. 3 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 'L1' between the two sets of teeth 20 and 30.Since the plates 41 and 42 are held fast to the hub flange 12, by the tabs 47 on the washer 52 and the flange plates 43 are held fast to the hub 11, the initial resistance to rotational movement is due to the friction damping generated between the side plates 41 and 42 and the two flange plates 43, the rubbing of the spring washer 57 on its adjacent surfaces and by the first stage damping springs 48. In this case all the first stage springs are shown co-operating together. This is the stage A of the graph in Fig 10. This stage A continues until the lost-motion clearance 'L1' between the teeth -30 on the flange 12, and the teeth 30 on the hub 11, has been taken up (see Fig 1A.). This this ends the operation of the first stage damper.

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 and between the washer 52 and the retainer plate 19 under the bias of the spring washer 58. The friction facing continues its relative anti-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 B, during which the main torsion springs 15 may 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 same sequence of events takes place with the first stage damper operating followed by the main torsion damping spring 15. The manner in which the resistance to rotation operates in this over-run mode can be altered by changing the operating clearance in this direction of rotation as compared with the drive mode direction of rotation.

For example in the hub (see Fig. 1A) the clearance L2 in one direction can be less than L1 in the other direction.

Claims

1. A rotary coupling comprising a central annular flange means, and a pair of coaxial annular side plates arranged one on each side of the flange means and which are rotationally fast with each other, the side plates being capable of limited rotational movement relative to the flange, said flange means comprising two coaxial flange plates arranged side-by-side with a spring washer located between the two flange plates to bias each plate into frictional engagement with a side plate so as to resist rotational movement between the side plates and the flange plates.

2. A rotory coupling as claimed in Claim 1, and further including spring means acting between the side plates and the flange plates to resist said angular rotation.

3. A friction clutch driven plate comprising a hub and a friction facing carrier mounted on the hub and capable of limited angular movement about the hub, wherein a rotary coupling according to Claim 1 or Claim 2 is operably located between the facing carrier and the hub to resist an initial phase of angular movement of the facing carrier around the hub.

4. A friction clutch driven plate as claimed in Claim 3, wherein the flange plates are rotationally fast with the hub, and the side plates are connected to the facing carrier.

5. A friction clutch driven plate as claimed in Claim 4 wherein the hub has an annular array of teeth on its outer periphery which mesh with teeth on the inner periphery of the hub flange such that the hub flange is capable of limited rotational movement relative to the hub, and the facing carrier is mounted on the hub for limited rotational movement relative to both the hub flange and the hub, said side plates being rotationally fast with the hub flange for movement of the side plates relative to the flange plates during the limited rotational movement of hub flange around the hub.

6. A friction clutch driven plate according to Claim 5, wherein the friction facing carrier comprises a carrier plate arranged on one side of the hub flange and a retainer plate arranged on the other side of the hub flange and which is rotationally fast with the carrier plate, and the rotary coupling is located axially between the hub flange and the retainer plate.

7. A friction clutch driven plate as claimed in Claim 6 wherein at least one of said side plates is connected to the hub flange by a washer having axially extending tabs thereon, said tabs being engaged in aligned aperatures in the hub flange and said one side plate.

8. A friction clutch is claimed in Claim 7 wherein a further spring washer is located between said one side plate and the washer to bias said washer into frictional engagement with the retainer plate.

9. A friction clutch driven plate substantially as described herein and with reference to the accompanying drawings.