Machine element or mechanism – Mechanical movements – Grip units and features
Reexamination Certificate
1999-01-20
2001-04-10
Fenstermacher, David (Department: 3682)
Machine element or mechanism
Mechanical movements
Grip units and features
C074S156000, C192S015000, C297S36700R
Reexamination Certificate
active
06212965
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a shiftable clamping-type locking mechanism, and in particular to a locking mechanism used in gearboxes for adjusting a seat position of a car seat.
In general, clamping-type locking mechanism of this type are used to secure the position between two elements. When releasing a locking mechanism, both elements can be moved in directions that have been previously locked. The locking mechanism is provided with tracks between which clamping members are positioned and so spring-loaded against these tracks as to seek a clamped position. The tracks may, for example, be formed on opposing outer cylindrical surface areas of both elements. It is also conceivable to design the tracks along confronting sides of longitudinally displaceable elements. Locking mechanisms of this type may be installed, for example, in gearboxes in which a shaft should be securely fixed in both directions of rotation. Such gearboxes are used, for example in seat adjustments of motor vehicles or in mechanisms for raising and lowering windows in motor vehicles.
International patent publication WO 96/20352 discloses a clamping-type locking mechanism for adjusting the seat position of a seat. The locking mechanism includes two elements nested within its other, with the outer element forming a cylindrical track about its inner surface area, and with the inner element being provided with several circumferentially spaced ramps extending about the outer surface area in opposition to the cylindrical track and inclined in opposite directions. Each ramp forms with the cylindrical track a wedge-shaped clamping gap in which a clamping roller is positioned under spring tension. As the imaginary peaks of the wedge-shaped clamping gap either face one another or, as in this case, face away from one another, the clamping rollers positioned under spring tension in the clamping gap prevent a rotation of the inner element relative to the outer element in both directions of rotation. When the clamping rollers are released and thus in cleared position, only those clamping rollers are actually freed which are functionally relevant for this direction of rotation. The clamping rollers are arranged in pockets of a cage at clearance in circumferential directions, whereby the cage can be slightly pivoted relative to the inner element. This pivot path is utilized for releasing the clamping rollers from their pertaining clamping gaps. A torque acts on the inner element and is effected by a force impacting on the seat. In the clamping situation, these types of locking mechanisms retain the seat at a set level.
These types of locking mechanisms are however subject not only to static torque in their clamped position but also to oscillating, dynamic loads with changing torque. In such a changing load, the clamping force, which is transmitted from the inner element via the clamped rollers into the outer element, is initially reduced in the conventional locking mechanism, until the changing load reaches a value at least approximating zero. Although in this stage, the clamping rollers are still resiliently received in their clamping gap by means of the provided springs; However, relative movements between the inner element and the outer element are possible because of the reduced clamping action as a result of the changing load. Thus, an undesired slip may be caused. In case of a seat adjustment, such relative movements result in an unintended change of the seat level.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide an improved clamping-type locking mechanism, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an improved clamping-type locking mechanism, in which a slip between clamped elements is positively eliminated.
These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a plurality of clamping members, e.g. rollers or balls, arranged between confronting tracks of two elements and so spring-biased as to seek a clamped position, a control unit which acts on the two elements for moving the clamping members from the clamped position into a release position in which the clamping members are liberated from the tracks so that the elements are freely movable relative to one another; and a coupling unit for detachably connecting both elements in a form-fitting manner.
Through the provision of an additional coupling unit, the locking mechanism according to the present invention can be operated without experiencing an undesired slip between both elements. The coupling unit can be dimensioned for small loads as the loads are predominantly transmitted via the locking mechanism. Only in circumstances when dynamic or changing loads reach or pass the value zero is the coupling unit subject to these small dynamic loads, preferably at zero crossing. The form-fitting engagement of both elements to one another is then able to positively eliminate undesired slip between the two elements.
The coupling unit is preferably disengaged when the clamping members occupy their release position and thus are liberated from the tracks. An adjustment of both elements relative to one another is then possible in a manner known per se. The coupling unit is engaged when the clamping members occupy their clamped position and thus are in engagement with the tracks.
According to another feature of the present invention, an actuating device is provided for operating the control unit and the coupling unit. In a neutral position of the actuating device, the clamping members are arranged in their clamped position, with the coupling unit being engaged. An actuating device of this type can be designed in many ways to initially engage the coupling unit and to subsequently liberate the clamping members to occupy their release position, when operating the actuating device in an actuating direction.
Advantageously, the coupling unit can be realized in a particularly simple manner by providing the one element with a first tooth profile and the other element with a second tooth profile, with both tooth profiles being displaceable relative to one another for effecting a tooth engagement. Suitably, the first element includes a shaft and a gear which represents the tooth profile of the first element and is so secured on the shaft that the gear is prevented from executing a rotation relative to the shaft but is able to move in axial direction relative to the shaft. The other element is then provided with the second tooth profile, with the shaft being rotatably mounted with respect to the other element. The coupling unit is engaged when the gear is so axially displaced as to mesh with the second tooth profile. When the gear is axially shifted along the shaft and dissociated from the second tooth profile, the coupling unit is disengaged.
Preferably, the coupling unit is operated by an actuating mechanism which includes a rotatably mounted actuator, whereby an indexing mechanism is positioned between the actuator and the gear for converting a rotational movement of the actuator into an axial movement of the gear for engaging and disengaging the coupling unit. The conversion of the rotational movement into an axial movement may be realized by providing the actuator with a cam surface for support of the gear, with the cam surface including at least one ramp and a support area following the ramp, whereby the ramp is inclined in rotational direction of the actuator with respect to a plane in which rotations of the actuator take place, and the support area extends parallel to the plane. When turning the actuator relative to the gear, the gear glides initially with its contact surface along the cam surface, i.e. along the sloped ramp and subsequently along the support area. When situated in the region of the support area of the cam surface, the gear of the one element has been shifted in axial direction to such an extent as to detach from the second tooth profile of the other element.
A
Feiereisen Henry M.
Fenstermacher David
Ina Walzlager Schaeffler OHG
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