192 clutches and power-stop control – Elements – Engaging surfaces
Patent
1992-07-08
1993-12-21
Lorence, Richard M.
192 clutches and power-stop control
Elements
Engaging surfaces
192107R, 188218XL, F16D 6904, F16D 1364
Patent
active
052714888
DESCRIPTION:
BRIEF SUMMARY
This invention relates to friction material facing and carrier assemblies particularly for friction clutch driven plates, and to a method of manufacture thereof.
It is known to manufacture a friction clutch driven plate by the use of adhesive to secure an annular friction facing to a support or carrier plate. In conventional driven plates an epoxy resin based adhesive may be used for this purpose.
It is desirable for the friction facing of a driven plate to have a certain degree of flexibility and axial cushioning. The epoxy resin adhesive film generally provides little or no compliance or cushioning.
The axial cushioning is desired to ameliorate a phenomenon known in the trade as "heat spotting", which leads to localised overheating of high spots on the friction faces of the driven plate ,flywheel, or pressure plate. The cushioning also helps to prevent clutch judder on take-up of the drive.
The necessary axial cushioning is generally provided between the opposed back faces of a pair of annular friction facings. This is conventionally achieved by mounting the facings on spring steel cushioning segments.
EP0252583A, describes the use of a silicone rubber adhesive for mounting a friction facing onto a carrier or support. The silicone rubber adhesive serves to secure the facing to its support and also provides the necessary axial cushioning, thus allowing a simplification of the driven plate construction. In PCT/GB88/00953 there is disclosed a construction in which the silicone rubber adhesive is formed in discrete concentrically spaced circles. Each circle of adhesive is described as being formed by a respective adhesive nozzle.
In a further development, disclosed in EP0323036, the silicone adhesive is applied to the reverse side of the friction facing is a continuous spiral of substantially three turns, the spiral starting radially inwardly of the facing and moving outwards.
This latter system has the advantage that only a single application nozzle is needed and that there are less problems associated with starting and finishing of the adhesive application process.
However, the spiral locus of the adhesive on the friction facing leads to an out of balance construction. As can be seen in FIG. 1, the elastomeric adhesive is laid onto the facing 2 in the form of a spiral 4 comprising three turns 4A, 4B, 4C. There are large areas X and Y of friction facing on both the radially inner and outer margins of the facing that are free of adhesive.
The present invention seeks to overcome the above problem whilst still ameliorating the problems already overcome in the known prior art.
According to the invention there is provided a friction material facing and carrier assembly for a clutch driven plate, and which comprises at least one annular friction facing secured to the carrier by a plurality of concentric circular stripes of adhesive elastomeric material which are coaxial with the facing, each circular stripe being interupted at only a single point on the circle to form a gap between the beginning and end of the respective circle, the interruptions in each circular stripe being radially aligned one with the other, and the end of one circular stripe is joined to the beginning of the adjacent concentric circular stripe so that the adhesive forms a continuous stripe from the radially inner margin of the facing to the radially, outer margin of the facing.
Also according to this invention there is further provided a method of making a friction material facing and carrier assembly having at least one annular friction facing secured to a carrier by adhesive applied to the back face of the facing, said method comprising the steps of extruding elastomeric adhesive material from a nozzle, causing simultaneous relative rotational movement between the nozzle and the facing so as to lay a substantially circular stripe of adhesive material onto the back face of the facing, and relatively displacing the nozzle radially just before the circle is completed, and repeating said operations as desired to form a desired number of concen
REFERENCES:
patent: 4821860 (1989-04-01), Crawford et al.
patent: 5076410 (1991-12-01), Maycock et al.
patent: 5137133 (1992-08-01), Graton et al.
Cooke Richard D. M.
Sleath Stuart J.
Automotive Products plc
Germain Lee A.
Lorence Richard M.
Milliken Paul E.
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