192 clutches and power-stop control – Clutches – Axially engaging
Patent
1994-09-08
1996-12-24
Pitts, Andrea L.
192 clutches and power-stop control
Clutches
Axially engaging
192 8924, F16D 1350
Patent
active
055866344
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is concerned in general terms with diaphragm clutches, especially for motor vehicles, and is directed more particularly to that part of these clutches, commonly referred to as the clutch mechanism, which, constituting by itself a unitary assembly, is to be fitted as such on a plate, referred to as a reaction plate, after a friction plate has been inserted, so as to constitute such a clutch.
In general terms, and as described in the document FR-A-2 463 874, such a mechanism comprises a hollow cover plate having at its outer periphery an annular skirt, oriented generally axially, at least one pressure plate, which is coupled in rotation to the cover plate through attachment means which enable the said pressure plate to be displaced axially with respect to the said cover plate, and, between the cover plate and the pressure plate, a diaphragm the outer periphery of which defines a Belleville ring, which, firstly, bears at its outer periphery on a deflection abutment carried by the cover plate, and, secondly, bears at its inner periphery on a projecting element of the pressure plate so as to urge the said plate in a direction in which it is displaced away from the cover plate.
Such a mechanism poses problems. In this connection, having regard to manufacturing tolerances, the diameter of the peripheral skirt of the cover plate may vary not insignificantly, for example in the order of 1 mm for a cover plate size having a diameter of the order of 220 mm.
The same is true, to a lesser extent, for the diaphragm, since its manufacturing tolerances are of course more strict, but it is subjected to ovality effects due in particular to the heat treatment to which it is subjected so as to give it a certain hardness and elasticity. For example, the diameter of the diaphragm may vary by 0.5 mm for a cover plate size with a diameter of 220 mm.
Conventionally, the mechanism is dynamically balanced before leaving the production line, but once it is fitted in the vehicle, this mechanism is no longer able to be dynamically balanced, the diaphragm being displaced with respect to the cover plate under the effect of parasitic movements such as shocks, wear in the deflection abutment, longitudinal and radial movements of the crankshaft of the engine, etc.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome these drawbacks in a simple and inexpensive way, and accordingly to provide a novel clutch mechanism which is dynamically balanced under all circumstances.
In accordance with the invention, a mechanism of the type described above is characterised in that the deflection abutment is of elastic material and carries an integral centring extension, oriented generally axially and interposed radially between the inner periphery of the skirt of the cover plate and the outer periphery of the diaphragm.
Thanks to the invention, the extension defines a resilient bearing which automatically centres the diaphragm with respect to the cover plate in the event of any relative movement of the diaphragm with respect to the cover plate.
Thus the dynamic balancing which is carried out on the production line will be preserved subsequently. In addition, the deflection abutment with its extension isolates the diaphragm with respect to the cover plate, so that the mechanism is not noisy, to the benefit of the comfort of the occupants of the vehicle.
It will also be appreciated that the deflection abutment enables wear and manufacturing tolerances, and in particular geometrical imperfections in the cover plate, to be compensated for.
In this connection, the cover plate, which is usually made by press forming, does not have perfect geometry, so that the engagement offered by the cover plate to the diaphragm is not regular, and as a result, some of the fingers of the diaphragm are offset with respect to the others.
Thus the clutch release bearing, acting on the ends of the fingers of the diaphragm, must bear first on the offset fingers and then on the others.
As a result, there is
REFERENCES:
patent: 5265709 (1993-11-01), Takeuchi et al.
Pitts Andrea L.
Valeo
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