192 clutches and power-stop control – Elements – Engaging surfaces
Reexamination Certificate
2000-12-21
2001-10-23
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Elements
Engaging surfaces
C192S052600
Reexamination Certificate
active
06305522
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to clutch discs or clutch plates of the type serving to transmit, or to interrupt the transmission of, torque between driving and driven rotary units, e.g., in friction clutches which are installed in the power trains of motor vehicles to transmit torque between a prime mover and a variable-speed transmission or between a transmission and a unit (such as a differential) which receives torque from the transmission.
A standard clutch plate or clutch disc (hereinafter called clutch disc) comprises a rotary support having a hub which can be non-rotatably mounted on the input shaft of a torque receiving unit (e.g., a transmission), and two annular friction linings which are affixed to the support and can be clamped between two coaxial rotary members (e.g., an axially movable pressure plate and an axially fixed counterpressure plate, such as a flywheel affixed to the output element of the internal combustion engine of a motor vehicle). The clutch can further comprise a so-called resilient cushion which is installed between the friction linings to yield during engagement and to dissipate energy during disengagement of the clutch.
Clutch discs of the above outlined character are disclosed, for example, in published German patent application Serial No. 30 23 634, in German Auslegeschrift No. 26 41 379, in German patent No. 27 20 664, and in U.S. Pat. Nos. 2,296,515 and 5,085,307.
When a friction clutch employing or cooperating with a clutch disc of the above outlined character is being engaged, the pressure plate is moved axially toward the counterpressure plate so that the two plates frictionally engage the adjacent exposed surfaces of the respective friction linings. At the same time, the two friction linings are caused to move axially toward each other and thus compress the resilient cushion between them. This entails a gradual (smooth) engagement of the clutch. During the initial stage of engagement of the clutch, the pressure plate and the counterpressure plate slip relative to the respective friction linings with attendant generation of friction heat, i.e., the temperature of the entire friction clutch rises. A serious drawback of such temperature change is that the conicity of the pressure plate increases or that the originally flat friction surface of the pressure plate assumes a conical shape. In fact, even the counterpressure plate (flywheel) of the clutch disc is likely to assume a conical shape which is undesirable even if it is less pronounced than the aforediscussed heat-induced conicity of the friction surface of the pressure plate.
The development of conicity at the friction surfaces of the pressure plate and counterpressure plate (also called reaction plate) results in the establishment of radially outwardly widening annular gaps between the two plates and the adjacent exposed surfaces of the respective friction linings. Reference may be had to the disclosure of U.S. Pat. No. 2,902,130. The development of such gaps, in turn, results in an unequal distribution of surface pressures upon the friction linings, as seen radially of the clutch disc, namely the surface pressure rises in a direction toward the axis of the clutch disc and decreases radially outwardly. Otherwise stated, the clutch disc exhibits a tendency to shift the effect of surface friction nearer to its axis. The result is a non-uniform wear upon the friction surfaces of the friction linings and a reduction of the maximal torque which can be transmitted by the clutch disc and the friction clutch embodying such clutch disc. The reason is a shift of the average effective friction diameter as a function of the radial distribution of surface pressure.
The only presently known solution of the above outlined problems is a replacement of the friction linings, a replacement of the clutch disc which employs such friction linings, or a replacement of the friction clutch which employs or cooperates with the clutch disc.
OBJECTS OF THE INVENTION
An object of the invention is to provide a clutch disc which is not affected, or which is not unduly affected, by the developing conicity of the pressure plate and/or counterpressure plate as a result of pronounced heating of a friction clutch which employs the clutch disc.
Another object of the invention is to provide a clutch disc which is designed in such a way that it can at least partially compensate for the developing conicity of the pressure plate and/or counterpressure plate as a result of heating during partial engagement or disengagement of the friction clutch.
A further object of the invention is to provide novel and improved friction linings for use in the above outlined clutch disc.
An additional object of the invention is to provide a novel and improved resilient cushion for use between the friction linings of the above outlined clutch disc.
Still another object of the invention is to provide novel and improved combinations of resilient cushion and friction linings for use in the above outlined clutch disc.
A further object of the invention is to provide a friction clutch which embodies the above outlined clutch disc.
An additional object of the invention is to provide a novel and improved method of counteracting the adverse effects of the development of conicity of the pressure plate and/or counterpressure plate as a result of overheating during partial engagement or partial disengagemet (slippage) of the friction clutch, e.g., a friction clutch between the internal combustion engine and the variable speed transmission in the power train of a motor vehicle.
Another object of the invention is to provide a clutch disc which is not affected (or not overly affected) by deformation of a pressure plate and/or counterpressure plate as a result of cooling of the friction clutch.
SUMMARY OF THE INVENTION
One feature of the instant invention resides in the provision of a clutch disc which comprises a support rotatable about a predetermined axis and normally comprising a centrally located hub adapted to be secured to a shaft (such as the input shaft of a variable speed transmission in the power train of a motor vehicle), and two washer-like annular friction linings which are coaxial and rotatable with the support. The friction linings are movable relative to each other in the direction of the axis of the support between first positions at a greater first distance from each other and second positions at a lesser second distance from each other. The clutch disc further comprises a resilient cushion which is disposed between the friction linings and is arranged to bias the friction linings in the direction of the axis of the support toward the first positions and to store energy (or additional energy) during movement of the friction linings toward the second positions, and means for blocking movements of the friction linings toward each other beyond the second positions.
As a rule, the friction linings are disposed between, and are movable from the first toward the second positions, by rotary first and second pressure plates of a friction clutch, such as an axially movable pressure plate and an axially fixed counterpressure plate (e.g., a flywheel secured to the output shaft of an internal combustion engine in the power train of a motor vehicle).
In accordance with a highly advantageous feature of the invention, at least one of the friction linings is tiltable relative to a fulcrum defined by the blocking means and constituting an annular pivot or seat having its center at or close to the axis of the support. Each friction lining has a side confronting the other friction lining, and the blocking means can comprise at least one projection provided at (e.g., forming part of) the side of the at least one friction lining. For example, the blocking means can comprise a first portion provided on one of the friction linings and a second portion provided on the other friction lining; at least one of the first and second portions can form part of the respective friction lining.
The blocking means can be designed in such a way that it co
Birk Albert
Busse Jurgen
Elison Hans-Dieter
Gunther Kraft
Lehmann Steffen
Bonck Rodney H.
Darby & Darby
LuK Lamellen Kupplungsbau GmbH
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