192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
2000-12-11
2002-09-03
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C192S111400
Reexamination Certificate
active
06443285
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a thrust plate assembly for a motor vehicle friction clutch with automatic wear compensation including a housing that is fixedly connectable to a flywheel for joint rotation with the flywheel about an axis of rotation, a pressure plate arranged in the housing such that the pressure plate is fixed with respect to rotation relative to the housing and axially displaceable relative to the housing, an energy accumulator having one side supported at the housing and another side supported at the pressure plate, and a wear adjustment device arranged in the support path of the energy accumulator between the energy accumulator and a component of the housing and pressure plate and including at least one adjustment element which is displaceable to compensate for wear, the wear adjustment device being operatively arranged for compensating for wear in proportion to the occurring wear.
2. Description of the Related Art
A prior art thrust plate assembly is disclosed in German reference DE-A-29 20 932 having a wear adjustment device with an adjustment ring with a plurality of surface regions arranged successively in circumferential direction. These plural surface regions are inclined relative to the circumferential direction and contact corresponding counter-surfaces of a pressure plate which are inclined relative to the circumferential direction. During a rotation of this adjustment ring in circumferential direction, i.e., in a wear adjustment movement direction, the surfaces and counter-surfaces slide against one another so that the adjustment ring is displaced axially in relation to the pressure plate and compensates, e.g., for wear occurring in the region of friction facings. The adjustment ring is pretensioned by an adjusting spring for movement in the circumferential movement direction. In this known thrust plate assembly, an area of a diaphragm spring acting on the adjustment ring is swiveled during a disengaging or releasing movement and the pressure plate follows this movement of the diaphragm spring essentially completely. However, if wear which is detectable by a play sensor of the thrust plate assembly has occurred previous to the disengaging movement, the release path of the pressure plate is limited so that at the end of the movement travel or lift of the diaphragm spring, the pressure plate no longer follows this lift and the wear adjustment device, i.e., the adjustment ring, is consequently released for carrying out the compensating movement mentioned above. The extent to which the pressure plate no longer follows the lifting off movement of the diaphragm spring corresponds precisely to the wear previously detected by the play sensor. The precise amount of this release path that is no longer traveled is compensated by the wear adjustment device. Therefore, the adjustment ring initially directly contacts the diaphragm spring again during an engagement process to be carried out subsequently and finally the diaphragm spring acts upon the subassembly formed of the pressure plate and adjustment ring to the precise extent and manner as with a clutch disk which does not exhibit any wear. Even when wear occurs, the installation position of the diaphragm spring does not change over the life of a thrust plate assembly of this type so that the releasing force required remains essentially the same and the clutch characteristic remains essentially unaltered.
SUMMARY OF THE INVENTION
An object of the present invention to provide a thrust plate assembly which has an improved capacity for adapting to operating conditions which change over the operating life of a clutch.
The object is met according to an embodiment of the present invention by a thrust plate assembly for a friction clutch in a motor vehicle with automatic wear compensation, comprising a housing fixedly connectable to a flywheel for joint rotation with the flywheel about an axis of rotation, a pressure plate arranged in the housing such that the pressure plate is fixed with respect to rotation relative to the housing and axially displaceable relative to the housing, an energy accumulator such as a diaphragm spring having one side supported at the housing and another side supported at the pressure plate, and a wear adjustment device arranged in the support path of the energy accumulator between the energy accumulator and a component of the housing and pressure plate. The wear adjustment device has at least one adjustment element which is displaceable to compensate for wear and is operatively arranged for effecting wear compensation in proportion to the occurring wear.
In the thrust plate assembly according to the present invention, the ratio of movement of the wear adjustment device to the amount of wear differs from 1:1.
As was already noted, the axial expansion of the subassembly formed of the pressure plate and adjustment ring when carrying out wear compensation in the prior art is exactly the same as the extent to which friction linings become thinner. However, it has been determined that other characteristics of the thrust plate assembly which change over its useful life are not accounted for by this arrangement. It has been recognized, for example, that the operating characteristic, i.e., force characteristic, of a spring element such as an energy accumulator changes over the operating life. This property of the spring element is taken into account by the present invention in that a compensation process is not implemented in a ratio of 1:1 to the actually occurring wear. Rather, it is ensured by diverging from this ratio of 1:1 in a defined manner that the installation position of the energy accumulator changes in spite of the occurrence of wear and the execution of a compensating movement compelled by the occurrence of wear.
According to the present invention, when a spring force decreases in a determined installation position due to fatigue, wear compensation may be effected to a determined degree while simultaneously bringing the energy accumulator into a position which allows the spring to generate a higher force than in the original installation position, i.e., in the new state. Therefore, the defined selection of the ratio, which now no longer takes into account the exact wear actually occurring, accounts for many different variables which are known to change over the operating life of a clutch. In this way, the operating characteristic of a thrust plate assembly of this type and a clutch outfitted with this thrust plate assembly may be maintained in an improved manner.
The thrust plate assembly according to the present invention may, for example, comprise at least one adjustment element that is movable in a wear adjustment movement direction corresponding to occurring wear and that the movement in the wear adjustment movement direction causes a displacement of at least one adjustment element in a compensating movement direction different than the wear adjustment movement direction, and that the extent of movement in the compensating movement direction for wear and the wear itself is in a ratio other than 1:1.
A desired ratio between the wear which occurs and is detected and the compensation that is actually implemented is achieved in that the at least one adjustment element moves in the wear adjustment movement direction with a surface inclined in the wear adjustment movement direction along a counter-surface. Alternatively, the desired ratio may be achieved in that the at least one adjustment element moves along a counter-surface inclined in the wear adjustment movement direction. In both cases, the angle of inclination of the surface or counter-surface is selected in such a way that the extent of movement in the compensating movement direction is in a ratio to wear other than 1:1.
To detect wear in operation, the thrust plate assembly according to the invention may have at least one play sensor arrangement with a detection element having a detection portion arranged for interacting with a component or subassembly for detectin
Lindner Joachim
Weidinger Reinhold
Mannesmann Sachs AG
Rodriguez Saul
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