GB2170871A

GB2170871A - Friction material and carrier plate assembly

Info

Publication number: GB2170871A
Application number: GB08600867A
Authority: GB
Inventors: Peter Frederick Crawford
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1985-02-12
Filing date: 1986-01-15
Publication date: 1986-08-13
Also published as: GB2170871B; AU5247686A; GB8600867D0; GB8503611D0; AU573416B2

Abstract

A friction material and carrier plate assembly 2 for a driven plate of a friction clutch comprises a steel disc 4 having a marginal portion 11 formed with through openings 14A spaced by spokes 18A flexible axially of the disc. On each side of the disc annular friction facings such as 20 partially overlie the openings 14A and are bonded to the spokes 18A. The friction facings are also flexible and may have grooves to promote cooling and assist such flexibility. <IMAGE>

Description

SPECIFICATION Friction material and carrier plate assembly This invention relates to a friction material carrier plate assembly.

Such an assembly may be used as part of the construction of a friction clutch driven plate particularly, though not exclusively, for the clutch of a motor vehicle.

The driven plate is intended and arranged for connection with an output shaft to transmit driving torque to the shaft, when the clutch is in use, to rotate the shaft with the driven plate about the axis of the shaft. To this end the driven plate can comprise said assembly of friction material and carrier plate, and a member connected to the carrier plate to receive driving torque from the latter, and said driving member being arranged and intended for connection to a said output shaft.

The driving member may have a passage or opening lined internally with axial splines to engage with axial splines on an exterior of the output shaft. For example the driving member may be a disc provided with the passage or opening or may be a disc fast with a hub formed with the passage or opening.

The driven plate may be arranged to allow some limited selective arcuate movement between the carrier plate and driving member and therefore the transmission of driving torque to the driving member from the carrier plate may be through torsion damping resilient means, for example helical springs known per se, constrained between the carrier plate and driving member.

In use in a clutch the driven plate may be releasably clampable between a flywheel or driving plate and a pressure plate under the action of spring means, for example, a diaphragm spring.

Friction clutch driven plates having annular friction facings adhered directly to both sides of a metal carrier plate are known having no cushioning between the facings, but this lack of cushioning gives rise to heat spotting caused by rubbing of the driven plate friction faces over high spots on the pressure plate and driving plate. Heat spotting can cause rapid breakdown of the friction material.To mitigate this drawback British Patent 2044864 discloses a friction clutch driven plate having two co-axial annular friction facings each moulded directly onto its own respective carrier plate, the two carrier plates being arranged back-to-back to present the friction faces of the facings in axially opposite directions, and being joined so that the backs of the carrier plates are resiliently spaced apart allowing the friction faces to flex on contact with a driving member surface when applied to the faces under an axial load. This is a relatively complex construction.

An object of the invention is to provide a friction material and carrier plate assembly of relatively simple construction and capable of axial compliance so that when used in a friction clutch driven plate disadvantages associated with heat spotting may be avoided or at least mitigated.

According to the invention there is provided a friction material and carrier plate assembly comprising a carrier plate substantially in the form of a disc supporting two substantially co-axial annularly disposed friction facings, said carrier plate being for rotation about a central axis and having an marginal region adjacent to an outer periphery of the carrier plate, the marginal region comprising a continous outer peripheral portion surrounding a radially inner portion having through openings therein, said marginal region being sandwiched between the two friction facings overlying the openings and secured to opposite faces of the marginal region, said friction facings being capable of flexing or deforming axially, and parts of the carrier plate between adjacent openings being resiliently flexible axially.

Preferably the friction facings are directly bonded to the marginal portion.

Preferably one or more of the openings is/are only partially covered by at least one of the friction facings.

The invention will now be futher described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a diagrammatic plan view of an embodiment material and carrier plate assembly formed accordig to the invention and intended to form part of a friction clutch driven plate; Fig. 2 is a diagrammatic section on line ll-ll in Fig. 1, and Figs. 3 to 9 are respectively diagrammatic plan views (on enlarged scale relative to Fig.

1) of second to eight embodiments of friction material and carrier plate assemblies formed according to the invention.

In the drawings like references refer to like or comparable parts.

With reference to Figs. 1 and 2 the assembly 2 comprises a steel carrier plate 4 of disc form centrally apertured at 6 to fit, for example, on an internally splined hub known per se (not shown) when the assembly is incorporated in said driven plate. Also the carrier plate is formed with windows 8 for torsional vibration damping springs (not shown) known per se and holes 10 for stop rivets (not shown) known per se.

Adjacent to outer periphery 12 the carrier plate has a marginal region 11 extending radially inwardly from the periphery 12 to an inner limit indicated approximately by dot-dash line 13. The marginal region 11 comprises a continous outer peripheral portion 15 surrounding a radially inner portion indicated approximately at 17 in which an annular array of through openings 14 (identified at 14A in Figs. 1 and 2) is formed. The array of openings 14A is centred on axis X. Preferably radially outer ends 16 of the openings 1 4A are close to the outer periphery 12 so that oppposite each opening the peripheral portion 15 is radially quite thin.Between each opening 1 4A is an adjacent spoke or spacing part 18 (identified at 1 8A in Figs. 1 and 2) which is integral with the carrier plate since each part 18 is constituated by residual plate material remaining after the openings 14 are formed in the inner portion 17 of the marginal region 11. In the example the openings 14A are all substantially similar and are substantially equi-angularly spaced one from another about the axis X.

At the aforesaid marginal region 11, two substantially coincident and co-axial annular friction facings 20 and 22 are respectively secured to opposite faces of each spacing part 18A. Preferably the facings 20,22 are directly bonded to the spacing parts 18A. The bonding technique may require application of adhesive both to the face of the spacing part 18A and to the portion of the friction facing to be bonded to the spacing part.

Preferably the outer periphery 24 of each friction facing is close to the periphery 12 of the carrier plate. However, it also preferred that the radially outer end 16 of each opening 14A is disposed radially outwardly beyond the periphery 24. Also it is preferred that a radially inner end 26 of each opening 14A is disposed radially inwardly beyond the inner periphery 28 of each friction facing 20,22. Thus, although the friction facings overlie the openings 14A cooling air can flow radially along the open ended passages or air gaps provided by the openings between the friction facings.

The spacing parts 18 (18A in Figs. 1 and 2) are resiliently flexible in the axial direction of the axis X and are therefore in the nature of leaf-springs of which the flexing can be facilitated by making the radial dimensions between ends 16 of the openings and the plate periphery 12 small. Each friction facing 20 or 22 can be formed of any friction material know per se and may be of a non-asbestos type but is somewhat resilient such that each facing can flex or deform axially. Such flexing or deformation can reduce chance of heat spotting and can take place: (i) opposite the openings 14A, for example by displacement of a portion of a friction facing into the opening, and (ii) at flexed spacing parts 18A.

In Figs. 1 and 2 all the spacing parts 18A are substantially similar and with respect to the axis X the angular width of each spacing part is substantially the same as the angular width of each opening. Therefore, about 50% of the surface of each friction facing 20 or 22 facing towards the carrier plate is not directly supported by the spacing parts. This amount of unsupported surface may be reduced or increased as will be understood from the embodiments in Figs. 3 to 6 and 8 and 9.

In Fig. 3 the openings 14 are identified at 1 4B and with respect to the central axis are angularly wider than the spacing parts 18 identified at 18B.

The openings 14 in Fig. 4 are indentified at 14C and are angularly less wide than the spacing part 18 identified at 18C.

In Figs. 5 and 6 respectively, the openings 14 (respectively 14D in Fig. 5 and 14E in Fig.

7) are still only partially covered by the friction facings 20,22 though in Fig. 5 the radially inner ends 26 of the openings 14D are covered by the friction facings 20,22 whilst Fig.

6 shows the radially outer ends 16 of the openings 14D covered by the facings. Peripheries 12 and 24 of the carrier plate 4 and the friction facings respectively may substantially coincide in a modification of the embodiment shown in Fig. 6. In Figs. 5 and 6 air passages could be maintained between the friction facings at the openings if one of the friction facings covers the openings in like manner to that in Figs. 1, 3 or 4 or one facing covers the opening as in Fig. 5, and the other facing covers those openings as in Fig. 6.

In the foregoing the openings 14 and spacing parts 18 are generally radial. Their disposition may be non-radial. For example, Fig. 7 shows openings identified at 14G and spacing portions at 18G which are raked. This can promote flow of cooling air through the passages at the openings.

The openings 14 can be of any desired shape. In Fig. 8 the openings identified at 14H are circular.

Fig. 9 shows an embodiment in which the marginal region of the the carrier plate is formed with a plurality of annular arrays of openings identified at 14J and wherein the spacing parts 1 8J interconnect in a form of zig-zag.

Grooves may be formed in the friction face of any of the facings 20,22. This can promote cooling and increase flexibility of the facings.

As will be understood from Figs. 1 to 8 it is preferred that the openings 18 extend wholly or at least a greater part of the way across the radial width of the friction facings 20,22 In previously proposed carrier plate and friction materials assemblies, two annuli of friction material are solidly bonded without cushioning to continuous, solid peripheral margin portions at opposite sides of the carrier plate so that each annulus is continuously supported over the whole area of one of its faces by the carrier plate. In the case of the assembly 2 formed in accordance with the invention and as described with reference to the drawings only portions of surfaces of the facings 20, 22 are in contact with the carrier plate and in use wear of the friction facings can be less, for the same amount of use, than in previously proposed assemblies.

Also the carrier plate 4 in the assembly 2 may be of thinner metal than in said previously proposed assemblies so that weight and inertia may be reduced.

Claims

1. A friction material and carrier plate assembly comprising a carrier plate substantially in the form of a disc supporting two substantially co-axial annularly disposed friction facings, said carrier plate being for rotation about a central axis and having an annular marginal region adjacent to an outer periphery of the carrier plate, the marginal region comprising a continous outer peripheral portion surrounding a radially inner portion having through openings therein, said marginal region being sandwiched between the two friction facings overlaying the openings and secured to opposite faces of the marginal region, said friction facings being capable of flexing or deforming axially, and parts of the carrier plate between adjecent openings being resiliently flexible axially.

2. An assembly as claimed in Claim 1, in which the friction facings are bonded to the marginal portion.

3. An assembly as claimed in Claim 1 or Claim 2, in which said openings are partially covered by the friction facings.

4. An assembly as claimed in Claim 3 in which an air gap for the flow of air therethrough between the friction facings exists at said partially covered opening.

5. An assembly as claimed in Claim 3 or Claim 4 in which a side of said opening extends non-radially relative to the axis from a radially inner point of the side to a radially outer point of said side.

6. An assembly as claimed in Claim 5, in which said air gap or opening is in raked disposition relative to the axis.

7. A friction material and carrier plate assembly substantially as herein before described with reference to Figs. 1 and 2 or with reference Figs. 3,4,5,6,7,8 or 9 of the accompanying drawings.

8. a friction clutch driven plate including an assembly as claimed in any one preceeding claim.

9. A frictin clutch including an assembly as claimed in any one of claims 1 to 9.