Chairs and seats – Movable back – Tiltable
Reexamination Certificate
2001-06-12
2003-05-27
Cuomo, Peter M. (Department: 3636)
Chairs and seats
Movable back
Tiltable
C297S369000, C297S373000
Reexamination Certificate
active
06568759
ABSTRACT:
The present invention concerns an adjusting device for carrying out an adjusting function. Adjusting devices of this type are used, for example, as seat adjusters in motor vehicles. The present invention particularly concerns those adjusting devices in which a clamping roller switch gear and a switchable clamping roller locking gear are coupled to each other.
The clamping roller switch gear is an infinitely variable step-by-step switch gear with which a motor vehicle seat, for example, can be adjusted. A drive element and a driven element define, together with opposing clamping surfaces, wedge-shaped clamping gaps which taper in opposite directions and in which clamping rollers are arranged. Housing-fixed stops are provided which keep the clamping rollers disengaged from the clamping surfaces when the drive element of the clamping roller switch gear is not activated. In this way, it is assured that the driven element is rotatable in an idling or in an initial position of the drive element. If the drive element is moved out of its initial or idling position, the drive element effects a work stroke. The return movement of the drive element into the initial position is an idling stroke during which the driven element is not activated. During the work stroke of the drive element in the one direction, the one clamping rollers are brought into clamping engagement with the clamping surfaces, while the respective other clamping rollers are fixedly supported on the housing and remain disengaged from the clamping surfaces. During the idling stroke, those clamping rollers that were previously clamped are disengaged from the clamping surfaces due to the reversal of movement, while the other clamping rollers remain supported on the housing-fixed stops and disengaged from the clamping surfaces even during the idling stroke. Therefore, no entrainment of the driven element takes place during the idling stroke.
The switchable clamping roller locking gear is connected to the driven element of the clamping roller switch gear so that a rotation of the driven element of the clamping roller switch gear causes an entrainment of the driven shaft of the switchable clamping roller locking gear. When the clamping roller switch gear is not activated, the switchable clamping roller locking gear effects that a torque introduced into the driven shaft of the locking gear from the outside is transmitted to a housing which is preferably fixed on a frame. This is possible because clamping rollers arranged between the driven shaft of the clamping roller locking gear and the housing are in a state of locking readiness with their clamping surfaces in both directions of rotation. The clamping surfaces are arranged on the housing and the driven shaft and define clamping gaps for the clamping rollers. In the case of a motor vehicle seat, the torque applied from the outside to the driven shaft is produced by the weight of the seat or by spring forces and/or the weight of a person occupying the seat. The switchable clamping roller locking gear therefore prevents an accidental variation in the height of the seat.
BACKGROUND OF THE INVENTION
One example of an adjusting device, particularly for a motor vehicle seat is known from EP 0 631 901 B1. Among other things, an adjusting device is disclosed in which a clamping roller switch gear (FIGS. 2 and 3 of EP 0 631 901 B1) and a switchable clamping roller locking gear (FIG. 13 of EP 0 631 901 B1) are coupled to each other. A pivoting lever of the clamping roller switch gear comprises a substantially circular recess into which an inner element engages. In the annular space defined between the inner element and the wall of the recess, a plurality of circumferentially spaced clamping rollers are arranged that are spring-biased against housing-fixed stops. A plurality of circumferentially spaced radial constrictions of the annular space are formed by an appropriate shaping of the recess, so that the wall of the recess and the outer peripheral surface of the inner element define wedge-shaped clamping gaps in which the clamping rollers are arranged. The inner element is rotationally fixed to dogs that engage between clamping rollers of the switchable clamping roller locking gear as will be described more closely below.
The housing-fixed stops for the clamping rollers of the clamping roller switch gear at first effect that the clamping rollers of the clamping roller switch gear remain disengaged from their clamping surfaces when the pivoting lever is not activated, i.e. when it is in its idling initial position. The pivoting lever can be pivoted in both directions of rotation out of its initial idling position, a pivoting in one of the two directions of rotation being called a work stroke and a pivoting of the lever back into its initial position being called an idling stroke. In the prior art adjusting device, a work stroke in clockwise direction causes the clamping rollers situated on the right-hand side of the housing-fixed stops to be drawn into their clamping gaps so that the inner element can be pivoted together with the pivoting lever. Due to this pivoting motion, the clamped clamping rollers approach the other clamping rollers situated on the left-hand side of the housing-fixed stops. This course of movement is due to the fact that the clamping rollers on the left-hand side are supported on the housing-fixed stops and are retained in a state of disengagement from their clamping surfaces. Thus, during the work stroke, the pivoting lever and the inner element are pivoted in common past the clamping rollers that are supported on the housing. When the pivoting lever is released, the previously clamped clamping rollers slip or roll out of clamping engagement due to the changed direction of pivot of the pivoting lever. The other clamping rollers are not yet in clamping engagement because the associated clamping ramps that are disposed on the pivoting lever are at a distance from these clamping rollers. Therefore, during this idling stroke, no rotation of the inner element takes place. A renewed displacement of the pivoting lever out of its initial position in clockwise direction therefore effects a further rotation of the driven shaft in clockwise direction.
The inner element comprises dogs (FIG. 13 of EP 0 631 901 B1), each of which engages between two peripherally adjacent clamping rollers of the switchable clamping roller locking gear. The clamping rollers are arranged in an annular space defined between a stationary housing and a driven shaft, wedge-shaped clamping gaps for the clamping rollers being defined between the cylindrical inner wall of the housing and the clamping ramps of the driven shaft. The clamping rollers are biased by compression spring into their clamping gaps so that a permanent locking readiness is assured. A rotation of the dogs causes the one clamping rollers to be pressed out of the associated clamping gaps so that a rotation of the driven shaft of the switchable clamping roller locking gear can take place. The driving power transmitted by the dogs is introduced into the driven shaft of the switchable clamping roller locking gear by the clamping rollers. The rotation of the driven shaft serves to adjust the seat.
In the adjusting device described above, it must be assured that the inner element of the clamping roller switch gear is perfectly mounted because this inner element is vital to the functioning of the clamping roller switch gear and for the functioning of the switchable clamping roller locking gear. If this inner element is not properly mounted, it is possible, for example, for the inner element to tilt so that, on the side of the switchable clamping roller switch gear, the wedge-shaped clamping gaps get altered and, on the side of the switchable clamping roller locking gear, the point of application of the dogs on the clamping rollers is changed. Both consequences are disadvantageous because they can lead to a malfunctioning of the machine elements or even to a complete failure of the adjusting device. The discussed prior art offers no soluti
Cuomo Peter M.
INA Walzlager Schaeffler oHG
Muserlian Lucas and Mercanti
White Rodney B.
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