192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
1998-05-06
2001-01-23
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C192S111400
Reexamination Certificate
active
06176360
ABSTRACT:
The present invention relates to a friction clutch, in particular for a motor vehicle, and more particularly it relates to a clutch equipped with a device for compensating for wear, due in particular to wear in the friction liners, the said device, referred to hereinafter as a wear compensating device, operating as the said liners become worn.
A conventional friction clutch generally includes a reaction plate, which may be in two parts so as to constitute a torsion damper, and which is mounted in rotation on a first shaft, which is typically a driving shaft such as the crankshaft of the internal combustion engine and which supports, through its outer periphery, a cover plate to which at least one pressure plate is attached.
The pressure plate is coupled in rotation to the cover plate and to the reaction plate, while being able to be displaced axially under the action of controlled axially acting resilient means, consisting generally of a metallic diaphragm which bears on the cover plate, while a friction disc, carrying friction liners at its outer periphery and fixed in rotation to a shaft, typically a driven shaft such as the input shaft of the gearbox, is interposed between the pressure plate and the reaction plate in such a way as to be gripped between them when the clutch is in an engaged condition. The diaphragm controls the axial displacement of the pressure plate when it is actuated by a clutch release bearing. More precisely, the peripheral portion of the diaphragm constitutes the above mentioned resilient means, or clutch engaging means, controlled by the declutching means, which in the present case are the fingers of the diaphragm. The clutch engaging means, when they are actuated by the clutch release bearing, counteract the action of the declutching means.
In the course of the useful life of such a clutch, the friction liners become worn along with the counter materials, i.e. the pressure plate and reaction plate, and this causes variation to take place in the position of the pressure plate and those of the axially acting resilient means and the clutch release bearing, from which there follows a variation in the gripping force exerted between the friction disc on the one hand and the pressure and reaction plates on the other hand, because of the changes that take place in the working conditions (or positions) of the diaphragm, and the force necessary to disengage the clutch is consequently affected. By equipping such a clutch with a wear compensating device, these drawbacks are avoided, the diaphragm and the clutch release bearing, which is typically in constant engagement on the diaphragm, occupying the same position when the clutch is in its engaged condition.
It has already been proposed, in the document U.S. Pat. No. 5,090,536, to provide a take-up device by arranging between the diaphragm and the pressure plate two annular sleeves carrying complementary ramps, a first annular sleeve being fixed in rotation with respect to the pressure plate, the second one being displaceable in rotation with respect to the latter and to the first sleeve, with the relative circumferential displacement of the two sleeves leading, due to the complementary ramps which they carry, to the sleeves moving apart in the axial direction so as to compensate for the said wear, this movement apart of the sleeves simulating an increase in the axial thickness of the pressure plate; for its relative displacement in rotation, the second sleeve is provided at its periphery with a toothed sector, the teeth of which mesh with a worm which is disposed tangentially and which is mounted in rotation on a shaft carried by the cover plate of the clutch; the worm is arranged to be driven in rotation by means of a uni-directional coupling, through a drum carried by the same shaft that carries the worm, which drum is itself driven in rotation when wear occurs in the liners of the friction disc; the uni-directional coupling is so arranged that the worm is driven by the drum, which constitutes a kind of arming member for the device when the latter is itself driven in rotation during the declutching operation, the rotation of the worm leading to rotation of the second sleeve as stated above.
A uni-directional coupling disposed between the worm and the shaft that supports it enables the latter to keep its rotational position after each adjustment.
Such a device, in accordance with the document U.S. Pat. No. 5,090,536, has the following disadvantages: the arming member which is carried by the cover plate of the clutch, is liable to become driven in rotation by a lever which is itself controlled by the clutch release bearing; beyond that, the clutch release bearing must be specifically adapted for control of the said lever, and is bulky in the axial direction; in addition, when the clutch release bearing is caused to be displaced axially beyond the course of travel that is just necessary for the declutching operation, the take-up operation is effected when no wear has taken place, which is dangerous because it can lead to jamming of the clutch, which ends up by being no longer able to be disengaged.
An object of the present invention is to overcome these disadvantages.
According to the invention, a friction clutch, especially for a motor vehicle, of the kind comprising a reaction plate adapted to be mounted in rotation on a driving shaft, a friction disc carrying friction liners at its outer periphery and adapted to be mounted in rotation on a driven shaft, a pressure plate, a cover plate fixed on the reaction plate, axially acting resilient means acting between, firstly, the cover plate, and secondly, the pressure plate through abutment means, the pressure plate being fixed in rotation to the cover plate while being able to be displaced axially with respect thereto and being subjected to the action of resilient return means for returning the pressure plate axially towards the cover plate, the said clutch further including a wear compensating device comprising circumferentially disposed ramp means located axially between the abutment means and the pressure plate and adapted to be driven in rotation by means of a set of teeth, which they carry at their periphery and with which a tangentially disposed worm cooperates, means for driving the worm in rotation being provided and being rendered operational by wear in the friction liners when the clutch is engaged, together with non-return means preventing the worm from turning in the direction counter to that in which it is driven in rotation by the means for driving it in rotation when they are operational, the worm, the non-return means and the means for driving the worm in rotation being carried by a support fixed to the cover plate, and the axially acting resilient means consisting of a diaphragm, is characterised by the fact that the means for driving the worm in rotation are controlled by the diaphragm.
The fact that the worm, the non-return means and the means for driving the worm in rotation are carried by the cover plate improves the precision with which wear is detected.
Preferably, the means for driving the worm in rotation are controlled by the diaphragm through an interposed tongue or control finger, constituting a control member, the course of travel of which is limited during operation of the clutch by a so-called control abutment.
Preferably, the ramp means consist of an annular ring having ramps which are inclined and spaced apart circumferentially; preferably, the pressure plate has pads or ramps which are arranged to cooperate with the ramps of the ramp means.
Preferably, the said annular ring further includes engagement zones consisting of the rounded upper edge of press-formed projecting elements disposed on circular arcs centred on the axis of the clutch and located radially outwardly of the ramps; thanks to this arrangement, firstly, the engagement zones are very long, and secondly, numerous ramps can be provided so that the contact pressures are minimised.
Preferably, the ramp means have an axial flange provided with ventilating apertures; pref
Blard Michel
De Briel Jacques Thirion
Doremus Olivier
Bonck Rodney H.
Liniak, Bernato Longarce & White
Valeo
LandOfFree
Friction clutch with wear adjusting device, in particular... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Friction clutch with wear adjusting device, in particular..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Friction clutch with wear adjusting device, in particular... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2526653