192 clutches and power-stop control – Transmission and brake – Torque-responsive brake
Reexamination Certificate
2000-03-08
2001-07-31
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Transmission and brake
Torque-responsive brake
C192S111400
Reexamination Certificate
active
06267218
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a clamp-type locking mechanism, as used, for example, in seat-height adjustments of motor vehicles.
Conventional locking mechanisms include a rotatable driven element which can be secured with respect to a holding element formed, for example, as housing by means of a releasable clamp connection in one, preferably in both, rotation directions. In case of a seat-height adjustment, a selected seat position can be implemented in this manner. An adjustment element is provided to release the clamp connection and to rotate the driven element with respect to the holding element. Thus, when incorporated in a seat adjustment, a rotation of the driven element results in a modification of the seat position.
A clamp-type locking mechanism is known, for example, from WO-A 96/20352, and includes a driven element which is rotatably received in a housing. Clamping ramps of the driven element and a cylindrical clamping track of the housing define clamping gaps for receiving spring-loaded clamp rollers. An adjustment element is swingable to a limited extent with respect to the driven element and engages between the driven element and the housing. The adjustment element includes engagement members which press the clamp rollers out of their clamping gaps in order to permit a rotation of the adjustment element in unison with the driven element. This clamp-type locking mechanism has furthermore a friction device for transmitting a friction moment between the housing and the driven element. This friction device prevents an undesired stick-slip effect by which the clamp rollers are clamped and released again in rapid sequence. This stick-slip effect may be caused by a torque applied on the driven element and acting in same direction as the adjusting moment introduced into the adjustment element. The friction device is formed here by a friction disk which is positively connected to the driven element and has an outer surface area which bears upon the cylindrical clamping track of the housing. This type of friction device suffers the drawback that the transmitted friction effect decreases as the wear of the friction surface progresses, so that the pressing action between the friction disk and the housing decreases with increasing material wear of the friction disk.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide an improved clamp-type locking mechanism, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to so improve a clamp-type locking mechanism, that a reliable transmission of the friction moment between the driven element and the holding element is insured.
These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a spring mechanism to load the friction device with its friction surface against the holding element.
The spring mechanism is suitably so configured that the spring rigidity and the spring travel allows self-adjustments of the friction device in response to a wear, thereby ensuring a sufficient contact pressure of the friction surface against the holding element.
The configuration of the friction device is, of course, dependent on the design of the clamp-type locking mechanism. For example, clamp-type locking mechanisms are conceivable in which the holding element has an end face arranged transversely to the rotation axis of the driven element and formed with a planar clamping track, whereas the driven element has an end face arranged transversely to the rotation axis and formed with circumferentially spaced clamping ramps. In this case, the friction surface is formed at an end face of the friction device, whereby the spring mechanism may include, for example, a biased disk spring for pressing the friction surface of the friction device against the planar clamping track.
The present invention is especially suitable for application in a clamp-type locking mechanisms, as disclosed, for example, in the afore-stated WO-A 96/20352. In a clamp-type locking mechanism of this type, the clamping track is formed by a housing wall of a cylindrical recess of a housing, whereby a shaft, which is arranged coaxially in the cylindrical recess, has an outer surface area positioned in facing relationship to the housing wall and including the circumferentially spaced clamping ramps. In this case, the friction surface is provided on the outer surface area of the friction device.
According to another feature of the present invention, the spring mechanism includes a spring-loaded ring, which is breached by an opening, for urging the friction surface of the friction device against the cylindrical clamping track. This results in a simple and particularly cost-efficient configuration.
According to still another feature of the present invention, the spring-loaded ring may have two diametrically opposite areas for receiving friction elements with respective friction surfaces which may be formed by a coating, applied on the ring. It is, however, also possible to provide the friction surfaces in the form of a friction lining which is applied onto the ring. The use of a friction lining is advantageous because wear of the friction lining can easily be compensated through adjusting the biased ring. In order to ensure that the ring and the areas with the friction surfaces are arranged in concentric relationship to the cylindrical clamping track, the ring is suitably provided between the areas with a centering cam which bears upon the cylindrical clamping track.
A clamp-type locking mechanism in accordance with the present invention may, of course, also be so configured that the holding element is formed as fixed axle with cylindrical outer surface area, whereby the axle is received in a bore of the driven element. The driven element is provided in this case at its bore wall with the clamping ramps.
REFERENCES:
patent: 3243023 (1966-03-01), Boyden
patent: 5248017 (1993-09-01), Schwarzbich
patent: 5896973 (1999-04-01), Hochmuth et al.
patent: 6066097 (2000-05-01), Kurita
patent: WO 96/20352 (1996-07-01), None
Hochmuth Harald
Ritter Joachim
Feireisen Henry M.
Ina Walzlager Schaeffler OHG
Lorence Richard M.
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