192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
2000-04-28
2001-10-02
Marmor, Charles A. (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C192S111400
Reexamination Certificate
active
06296099
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of friction clutches, and more specifically, to friction clutches having automatic adjustment mechanisms.
BACKGROUND OF THE INVENTION
A friction clutch, or brake, includes a driven member having a friction surface that wears over the life of the device. In order for the friction clutch to continue operating effectively, the relative position of the engaging members must be adjusted or realigned to compensate for wear that occurs on the friction surface.
A friction clutch operates by transmitting torque from a driving member, such as a flywheel, to a driven member, each member rotating about an axis. The driven member is interposed between the flywheel and a pressure plate. A release assembly cooperates with the pressure plate to selectively move the pressure plate axially in order to engage and disengage the friction clutch. As wear occurs on the friction surface of the driven member, the pressure plate moves axially toward the flywheel in order to engage the driven member. Components such as levers or biasing members that contact the pressure plate directly or indirectly are affected by the change in relative position of the pressure plate. Therefore, the change in position of the pressure plate must be compensated in order to maintain proper plate load and freeplay.
With most heavy duty friction clutches, the adjustment of a release bearing and spring assembly is manually achieved in order to compensate for wear on the friction surface of the driven member. Manual adjustment, however, requires continuous monitoring to determine if adjustment is necessary, as well as manpower to perform the adjustment. If the adjustment is not timely completed, the clutch will operate less effectively and will wear prematurely.
It is also known in the art to provide a friction clutch with an automatic adjustment mechanism. While a number of such mechanisms do compensate for wear, numerous parts are typically required to achieve the desired result. Furthermore, more components within a clutch will increase the complexity and cost of manufacture. Still further, a more complicated design will increase the likelihood of failure.
It is therefore a goal of the present invention to provide a friction clutch with an automatic adjustment mechanism which has a simple structure and minimal parts.
SUMMARY OF THE INVENTION
A friction clutch comprises an adjustment mechanism including a stationary annular cam, a rotating annular cam, a cam biasing spring, a fulcrum ring, a wear sensor and an adjustment limiting device. The friction clutch transmits torque from a driving member, having an axis of rotation, to a driven member coupled to an axially extending driven shaft for rotation therewith. A cover is coupled to the driving member for rotation therewith, and a pressure plate is coupled to the cover. The driven member is interposed between the driving member and the pressure plate and has a friction surface connected thereto. The friction surface engages the driving member for transmitting torque from the driving member to the driven member.
The stationary cam has a stationary cam surface and is centered about the axis of rotation and is rotatably fixed relative to the pressure plate. The stationary cam surface has a plurality of ramps thereon. The rotating cam has a rotating cam surface in contact with the stationary cam surface. The rotating cam surface has a plurality of ramps thereon. The rotating cam is disposed between the adjustment limiting device and the stationary cam. The rotating cam rotates with respect to the stationary cam to move an axial end of the rotating cam from a first axial position to a second axial position relative to the pressure plate.
The cam biasing spring has a first and a second end, the first end is received in the rotating cam, and the second end of the cam biasing spring is attached to the pressure plate. The fulcrum ring is centered about the axis of rotation and is operatively coupled to the cover. The wear sensor is disposed within an aperture located in the cover and has an axial range of travel from a stop position to a full travel position. The adjustment limiting device has an axial range of travel from a stop position governed by the pressure plate to a full travel position. The adjustment limiting device cooperates with the rotating cam to govern the amount of rotation of the rotating cam relative to the stationary cam.
A release assembly extends about the driven shaft. A radially extending lever is interposed between the release assembly and the adjustment mechanism. The lever is operatively disposed at an axial end of the release assembly at a first end and cooperates with the fulcrum ring adjacent to a second end. The lever also cooperates with the adjustment limiting device to move the pressure plate to engage and disengage the driven member. The lever further cooperates with the adjustment limiting device to cause an axial end of the rotating cam to rotate from a first position relative to the cover prior to wear to a second position relative to the cover after wear has occurred on the friction surface when the adjustment limiting device has a sufficient adjustment gap to allow the rotating cam to rotate to a second relative position where the second position is axially spaced from the first position limited by the adjustment limiting device.
In a second embodiment, the pressure plate has a stationary cam surface formed upon an axial surface. The rotating cam rotates upon the stationary cam surface with respect to the pressure plate to move an axial end of said rotating cam from a first axial position to a second axial position relative to the pressure plate.
In a third embodiment, the rotating cam has an adjustment limiting device in cooperation with the wear sensor, where the wear sensor governs the axial range of travel of the rotating cam when the rotating cam rotates with respect to the stationary cam surface.
Further objects, features and advantages of the present invention will become apparent to those skilled in the art from analysis of the following written description, the accompanying drawings and appended claims.
REFERENCES:
patent: 5090537 (1992-02-01), Fukuda
patent: 5513735 (1996-05-01), Uenohara
patent: 5513736 (1996-05-01), Mizukami
patent: 5566804 (1996-10-01), Gochenour et al.
patent: 5570768 (1996-11-01), Uenohara et al.
patent: 5934429 (1999-08-01), Jennings
Eaton Corporation
Marmor Charles A.
Musial, II Mitchell M.
Rodriguez Saul
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