192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
2000-08-29
2002-03-12
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C192S070270, C192S089240, C192S10900B, C192SDIG001
Reexamination Certificate
active
06354418
ABSTRACT:
The present invention relates to friction clutches, especially for motor vehicles, and is more particularly directed to the unitary assembly which is incorporated in such a clutch, as described for example in the documents FR-A-2 242 892 and FR-A-2 420 690. Such a unitary assembly is called a clutch mechanism.
A clutch mechanism conventionally comprises a reaction plate which is part of an engine flywheel, which may be divided into two parts so as to constitute, in particular, a torsion damped flywheel.
The reaction plate is fixed in rotation to a first shaft, such as a driving shaft, namely the crankshaft of the internal combustion engine in the context of application to a motor vehicle.
This reaction plate has a dorsal friction face, and is fixed in rotation to a pressure plate which is able to be displaced axially with respect to the reaction plate, also referred to as the engine flywheel.
The pressure plate has a front friction face.
The friction liners of a friction disc are interposed between the pressure plate and the reaction plate, and more precisely between the friction faces of these latter.
These liners are fixed to a support which is usually axially deformable elastically. In another version, the support is rigid, being for example encapsulated at its outer periphery within a single friction liner. The said support, which may be double, is rigidly or elastically connected to a hub which is fixed in rotation to a second shaft, such as a driven shaft, namely the input shaft of a motion transmission means, for example a gearbox in the context of application to a motor vehicle.
When the friction liners are gripped between the pressure plate and reaction plate (clutch engaged), the torque is transmitted from the driving shaft to the driven shaft via the friction disc. When the friction liners are not gripped between the said plates (clutch disengaged), the driven shaft is not driven by the driving shaft. For this purpose, axially acting clutch engaging means are provided, and constitute a unit with declutching means which are arranged to counteract, when required, the action of the clutch engaging means bearing on a cover plate, so as to act on the pressure plate, and more precisely so as to act on engagement means carried by the pressure plate, which is fixed in rotation to the cover plate while being able to be displaced axially with respect to the latter, for example with the aid of a coupling using axially elastic tongues, or with the aid of a tenon and mortice type coupling, in which radial lugs, forming tenons, of the pressure plate are engaged for axial sliding movement in grooves, forming mortices, of the cover plate.
The cover plate has at its outer periphery fastening means for securing it to the reaction plate, either detachably or permanently.
The clutch engaging means include at least one Belleville ring, and the declutching means include declutching levers for acting on the clutch engaging means. Usually, these clutch engaging and declutching means are part of one common component, elastic in the axial direction, which is a so-called diaphragm. This diaphragm, which is of frusto-conical form in the free state, has a peripheral portion in the form of a Belleville ring, which is extended radially towards the centre by a central portion divided into radial fingers by blind slots with widened bases, to define widened apertures at the inner periphery of the Belleville ring that constitutes the axially acting clutch engagement means, while the radial fingers constitute declutching levers and therefore the declutching means of the clutch.
In the documents FR-A-2 242 892 and FR-A-2 420 690, the cover plate constitutes, with the pressure plate, the resilient tongues and the diaphragm, a unitary assembly or so-called clutch mechanism which is fixed on the reaction plate. This clutch mechanism may of course constitute, with the friction disc and the reaction plate, a module which is attached in a unitary manner on the crankshaft of the engine of the vehicle or on a radial plate fixed to the crankshaft, with the reaction plate then being secured on the radial plate, which is preferably flexible.
This mechanism may be equipped with a wear compensating device for the friction liners and the friction faces of the pressure plate and reaction plate, in order that the diaphragm can be in a substantially constant position when the clutch is engaged, over the working life of the friction clutch.
This wear compensating device usually comprises ramps and counter-ramps which act between the pressure plate and the engagement means of the diaphragm, or between the diaphragm and the cover plate. An initiator, which is sensitive to the state of wear in the friction liners, enables the ramps to be rotated in the event of wear in order that the diaphragm will always occupy the same position when the clutch is engaged under the action of the clutch engaging means (liners gripped).
The initiator may include an elastic wear sensor or a system having a ratchet wheel and a worm, incorporated in a cassette.
Other versions may be envisaged.
In the documents mentioned above, the cover plate has a base portion, oriented transversely and open in the centre, and including abutment lugs at its inner periphery.
It is on these transversely oriented abutment lugs that the fingers of the diaphragm bear when the clutch mechanism is no longer fixed on the reaction plate. This position is called the storage position. In this position the diaphragm is inclined by a large amount, and the pressure plate projects axially with respect to the free end of the cover plate.
The pressure plate is further away in the axial direction from the base portion of the cover plate than it is when the clutch is in its engaged condition. In that condition the diaphragm is generally flat.
As can be seen in the document FR-A-2 242 892, the abutment lugs are spaced apart circumferentially at regular intervals with the fastening lugs of the diaphragm, so as to mount the diaphragm for tilting movement between a primary abutment and a secondary abutment, these abutments being carried by the cover plate.
The abutment lugs are separated therefore in pairs by slots, in the middle of which the fastening lugs are located.
The primary abutment is formed by press-forming the cover plate, and the secondary abutment is defined by the fastening lugs extending through the widened apertures in the diaphragm. As can be seen in
FIG. 2
of the document FR-A-2 420 690, the secondary abutment is of course carried, in another version, by a crown ring.
The abutment lugs may also be fastening lugs and may in particular carry rivets or small fastening posts, or any other means, as described in the document FR-A-2 420 690.
An object of the present invention is to make use of the abutment lugs in a simple and inexpensive way.
According to the invention, a mechanism of the type defined above is characterised in that a support member carries at its outer periphery locating lugs which project radially outwards, in that the support member is in contact with at least a plurality of the declutching levers, while the locating lugs are in contact with the face of the abutment lugs facing towards the declutching levers, so that the locating lugs and the support member are inserted axially between the declutching levers and the abutment lugs by a connection of the bayonet type.
Thanks to the invention, the locating lugs and the support member together constitute a locating means or spacer which is inserted axially, in one embodiment, between the diaphragm and the abutment lugs, so as to maintain the diaphragm in a predetermined position during assembly and/or disassembly of the clutch mechanism.
The support member, with its locating lugs, constitutes an assembly and/or dismantling tool for the clutch mechanism. It also acts as a tool for protection of, especially, the resilient tongues which couple the pressure plate in rotation with the cover plate.
In all cases, it is possible to avoid modifying the cover plate. The declutching levers can of course be part
Liniak Berenato Longacre & White
Lorence Richard M.
Valeo
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