192 clutches and power-stop control – Elements – Wear compensators
Reexamination Certificate
2000-02-01
2001-07-03
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Elements
Wear compensators
C192S070251
Reexamination Certificate
active
06253897
ABSTRACT:
The present invention concerns a friction clutch mechanism, notably for a motor vehicle, and relates more particularly to a clutch equipped with a device for compensating for the wear due notably to the wear on the friction lining or linings, this device, hereinafter referred to as a wear take-up device, operating generally as the wear occurs on the lining or linings.
Description of Related Art
A conventional friction clutch generally has a reaction plate forming part of an engine flywheel, possibly in two parts in order to form a damping flywheel or a flexible flywheel, fixed with respect to rotation to the first shaft, usually a driven shaft such as the crankshaft of the internal combustion engine, and supporting through its external periphery a rear cover to which there is attached, with axial mobility, at least one front pressure plate.
The pressure plate is fixed with respect to rotation to the cover and reaction plate whilst being able to move axially under the action of axially acting engaging means controlled by disengaging means. The engaging means can consist of helical springs or two Belleville washers mounted in series, subjected to the action of disengaging levers forming disengaging means.
Generally, the engaging and disengaging means form part of the same piece, for example a metallic diaphragm bearing on the cover. The diaphragm can be mounted in series or in parallel with a Belleville washer in order to provide assistance for the disengagement force.
A friction disk, carrying friction linings at its external periphery, fixed with respect to rotation to the shaft, usually a driven shaft such as the input shaft of the gearbox, is interposed between the pressure plate and the reaction plate so as to be clamped between them when the clutch is in the engagement position in order to transmit the torque from the driving shaft to the driven shaft.
Conventionally, the friction linings are mounted on an axially elastic support coupled rigidly or elastically to the hub fixed with respect to rotation to the driven shaft. By virtue of this arrangement the friction disc assists the diaphragm during the operation of disengaging the clutch.
In a variant, the support is embedded at its external periphery in a friction lining.
Conventionally, the engaging means, cover and pressure plate form part of the unitary assembly referred to as a friction clutch mechanism.
The engaging means control the axial movement of the pressure plate when they are actuated by a clutch release bearing by means of the disengaging means.
The clutch release bearing can be controlled mechanically, hydraulically, electrically or electro-mechanically. The control can be of the manual, automatic or semi-automatic type.
During the service life of such a clutch, the friction lining or linings and the counter-materials, pressure plate and reaction plate wear, which cause a variation in the axial position of the pressure plate, that of the axially acting engaging means and that of the clutch release bearing, resulting in a variation in the axial clamping force between the friction disc on the one hand and the pressure and reaction plates on the other hand, because of the changes in the operating conditions of the engaging means, and the force necessary for disengaging is affected thereby. By providing such a clutch with a wear take-up device, these drawbacks are avoided, the engaging means, as well as the clutch release bearing, usually in constant abutment on the disengaging means, occupying the same position when the clutch is in the engagement position, which makes it possible to reduce the axial bulk of the friction clutch.
The French patent application No FR-96.11297 filed on Sept. 17, 1996 and published under the number 2 753 503 describes and depicts in FIGS. 21 to 26 a friction clutch mechanism, notably for a motor vehicle, of the type having a rear cover 52, a front pressure plate 51 connected with respect to rotation to the cover 52 while being able to move axially with respect to it, abutment means 14 carried by the pressure plate 51, axially acting engaging means 53 acting between the cover 52 and the support means 14, and a wear take-up device.
The wear take-up device comprises on the one hand means 41 with ramps 56 carrying a set of external teeth 59 and placed between the pressure plate 51 and the abutment means 14 in order to constitute a pressure plate 51, 54 with a variable thickness between its friction face and the abutment means 14 and comprises moreover a unit carried by the cover 52 and which includes a piece 62, secured to the cover 52, forming a support for fixing the unit to the cover 52.
The support 62 is roughly in a U-shape with a top central web 64, in the general form of a horizontal plate, oriented roughly tangentially, and two opposite lateral wings 65, 66, each of which extends vertically downwards in an axially oriented plane perpendicular to the top web and each of which has a hole 61 for rotatably mounting an assembly 67, 63, 60, the piece 62 forming a support having a front fixing lug 68 which extends vertically upwards in a transverse plane perpendicular to the overall axis of the mechanism from a front transverse edge of the plate forming a central web 64 and which is fixed by riveting to a peripheral edge of the cover 52.
The assembly has notably a shaft carrying a worm, a ratchet wheel and a helical spring. The support also carries an elastic member provided on the one hand with a control tongue on the other hand with a non-return catch.
The control tongue is able to be manoeuvred by an actuator forming part of the engaging means of the clutch and cooperates, as does the catch, with the teeth on the ratchet wheel.
The worm cooperates with the teeth on a set of teeth belonging to the ramp means produced in the form of a ring with ramps disposed axially between the support means of the engaging means and the pressure plate. The worm cooperates with this set of teeth and with means of guiding in rotation, comprising the helical spring, which are made operational by the wear on the friction lining when the clutch is engaged. The worm is mounted tangentially with respect to its associated set of teeth.
It is desirable to ensure good holding in the fixed position of the unit by means of its U-shaped support without for that purpose having recourse to additional lugs for fixing by riveting like the lugs 69 illustrated in FIGS. 23 and 25 in this same document.
SUMMARY OF THE INVENTION
To this end, the invention proposes a clutch mechanism of the type mentioned above, characterised in that the support has at least one axially oriented stabilisation lug which extends towards the rear through an opening formed in the cover and riveted by at least one roughly tangentially oriented horizontal abutment edge which constitutes an abutment surface for the stabilisation lug.
By virtue of the invention, the support is simplified since the stabilisation lug replaces the fixing lugs of the prior art. The unit is stable. In addition, by virtue of the opening, it is possible to reduce the bulk because the support enters the opening. This support can thus have greater length whilst being more stable and robust.
According to other Characteristics of the Invention:
the abutment edge is a bottom edge of the opening and the stabilisation lug is in vertical abutment, through its bottom face, on the bottom horizontal abutment edge in order to have a support of maximum length, which is very stable and compact since it fits within the contour of the opening;
the bottom horizontal abutment edge is offset radially inwards with respect to the plane of the plate forming the top central web in order to increase still further the stability of the support and of the unit;
the stabilisation lug extends from a rear transverse edge of the plate forming the top central web in the plane of the latter, and is then angled successively twice so that its rear free end portion extends horizontally in a plane offset radially downwards in order to reduce the bulk to the maximum possible extent and to fit within the co
Blard Michel
Graton Michel
Liniak Berenato Longacre & White
Lorence Richard M.
Valeo
LandOfFree
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