192 clutches and power-stop control – Clutches – Operators
Patent
1995-11-30
1997-11-18
Pitts, Andrea L.
192 clutches and power-stop control
Clutches
Operators
192 7027, F16D 1344
Patent
active
056878257
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns the diaphragm clutch mechanisms as described for example in the document FR-A-1 524 350.
Such a mechanism forms a unit assembly and includes a cover suitable for being attached to the reaction plate of the clutch, a diaphragm mounted on the cover by pivoting means pivotally fixing the diaphragm to the cover, a pressure plate fixed to the cover with respect to rotation whilst being mounted so as to be axially movable with respect to it using coupling means, such as tangential elastic tongues.
In this type of mechanism the diaphragm bears on the cover in order to act on the pressure plate so as to push it away from the cover.
More precisely, the pivoting means include studs fixed to the cover and having a head profiled so as to offer a support for the peripheral part, in the form of a Belleville washer, of the diaphragm.
The studs pass through broadened orifices 23 (FIG. 5) formed in the area where the fingers 22 of the diaphragm are rooted at the Belleville washer part 21 of the latter.
These orifices are said to be broadened since they form one of the ends of the slots 24 separating the fingers 22 in pairs.
These orifices have a rectangular shape overall with lateral edges 25 designed to cooperate with an annular-shaped guide portion, in this case cylindrical, which the stud has between its head and foot.
In practice it has been found that wear phenomena occur at this guide portion. This is due to the fact that the diaphragm is a hardened piece.
The object of the present invention is to mitigate this drawback.
SUMMARY OF THE INVENTION
According to the invention a mechanism of the type indicated above is characterised in that its guide portion is cut into to form two lateral edges overall in the form of flats designed to cooperate with the lateral edges of the broadened orifices of the diaphragm.
Thus the wear on the said guide portions is reduced by increasing the contact surfaces, to the benefit of better functioning of the diaphragm because these lateral edges have a height greater than the thickness of the diaphragm.
The mechanism therefore has better reliability, its service life being increased.
It will be noted that the edges are overall in the form of flats since they can be slightly convex, notably when the studs are produced by forging. The lateral edges are therefore parallel to each other overall.
These studs are hardened, for example by a quench-hardening and annealing operation.
As a variant the studs can be in two parts, namely a first part fulfilling the functions of pivoting and guiding the diaphragm and a second part, in the form of a rivet, passing through the first part to fix the stud to the base of the cover.
This arrangement is particularly advantageous since the first part can easily be hardened, being for example produced from sintered steel, whilst the second part is produced by means of a standard unhardened rivet allowing easy fixing of the studs.
This second part supports only tensile loads.
The rivet can thus have a smaller cross section than when the stud is made in a single piece.
This rivet is also long, which makes it possible to achieve clamping of the diaphragm of the elastic type between its tilt supports, which is useful for reducing parasitic friction of the diaphragm pivot to a minimum.
In addition it is possible to reduce the size of the stud in its lower part, which is particularly advantageous, space being left for the friction disc.
The invention will be more clearly understood on a reading of the detailed description of the preferred embodiment of the invention which follows, and which is given by way of example only and with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in axial section of a mechanism according to the invention;
FIG. 2 is a partial view, to a larger scale, of a part of the mechanism in the top part of FIG. 1;
FIG. 3 is a view in the direction of the arrow 3 in FIG. 1 with local cutaway to show the pressure plate;
FIG. 4 is a plan view o
REFERENCES:
patent: 3939951 (1976-02-01), Sink et al.
patent: 4491211 (1985-01-01), Steeg
Giroire Jean-Pierre
Villata Gino
Pitts Andrea L.
Valeo
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