Length adjustment device for seats, specially motor vehicle...

Supports – Stand – Horizontally movable support surface

Reexamination Certificate

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Details

C297S341000, C297S344100

Reexamination Certificate

active

06170790

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a longitudinal adjusting device for seats, especially motor vehicle seats, whose backrest which is adjustable in selectable inclination positions is swivelably connected with a seat part, and the seat part is fastened to running rails, wherein every running rail is displaceable longitudinally in a guide rail fixed to the vehicle floor and at least one running rail can be secured to the guide rail in selectable longitudinal positions by means of a locking device, and at least one running rail is supported at the guide rail via a spring member for purposes of a forward displacement of the running rails.
2. Description of the Related Art
Longitudinal adjusting devices for seats of the type mentioned above are known in many constructional forms as can be seen, for example, from DE 32 26 198 A1or U.S. Pat. No. 4,143,911. Regardless of whether the displacement of the seat relative to the floor of the vehicle serves only for adjusting the longitudinal position of the seat or, when installed in two-door passenger automobiles, if it also serves to provide more space for rear seat passengers to board the vehicle, a spring element—e.g., an inherently elastic tension member—which reinforces the forward displacing movement of the seat is, as a rule, constructed as a helical tension spring which is connected on one hand with the running rail carrying the seat and, on the other hand, with either an articulation point of the vehicle floor or the guide rail which is fixed to the floor. Of course, it is also known to use helical pressure springs, wherein the articulation points are then reversed in a corresponding manner. Since a relatively large spring path is required for the longitudinal displacement of the seat, the selection of the springs according to their spring characteristic proves difficult inasmuch as the effective force should change only insignificantly from the start to the end of the displacing movement of the seat. However, this conflicts with the characteristics of helical tension springs and helical pressure springs of the type mentioned above which start at zero at the beginning of the spring path and, as the spring path advances, increase steadily to a maximum value at the end of the spring path. In order to achieve usable force ratios, springs of this type must have many turns and therefore have considerable length. This in turn requires a large space requirement for accommodating such helical tension springs and helical pressure springs.
SUMMARY OF THE INVENTION
It is the object of the invention to improve the spring device for reinforcing the forward displacement movement of the seat with its longitudinal adjusting device with respect to space requirement and the returning or restoring force. This object is met, according to the invention, in that a spiral spring is used as a spring member. Since the spiral spring takes up less space and, moreover, can be secured to a selectable location on the running rail, no significant installation space is taken up for this kind of return spring device. Further, the spiral spring can be tensioned in such a way that only a small rise or fall in force takes place over its useful range. In this respect, it will be apparent that the spiral spring, instead of the running rail, can also be associated with the floor of the vehicle or with the guide rail when the fixing point of the rope pull of the running rail is correspondingly associated with the return direction.
The spiral spring, as an automatically unwinding structural component part, can be fastened to the guide rail by one of its ends and to the running rail by its other end. However, as a rule, one end of the spiral spring is held in a stationary manner indirectly or directly at the rear area of the running rail, while the other end is held at a coiling or winding drum which is supported so as to be rotatable at the running rail, wherein one end of a pull rope is fixed to the winding drum and the other end of the pull rope is fastened to the front area of the guide rail.
A space-saving arrangement of the return spring device can be achieved in that the spiral spring is arranged in a hollow space of the winding drum and is connected by its inner end with a mandrel which is associated in a stationary manner with the running rail and on which the winding drum is mounted. The winding diameter can have either a constant or a changeable radius. For this purpose, a constructional unit can be advantageously provided in that the mandrel is a stationary, concentric component part of a can-like housing which surrounds the winding drum and which has, at its outer circumference, a slot for the passage of the pull rope fastened to the winding drum. For a reliable connection of the housing with the running rail, the housing may advantageously have, at its side wall, a carrying arm whose catch projections penetrate through bore holes in a holding cheek that is secured to the running rail.
An encapsulation of the constructional unit can be achieved so as to be substantially protected from soiling in that the housing is closable by means of a cover covering the spiral spring and the winding drum, wherein the housing, together with the spiral spring and the winding drum, forms a constructional unit.
In this case, the winding drum has, at its inner circumference, a receptacle for securing the outer end of the spiral spring whose inner end engages by a bent portion in a slot of the mandrel enclosed by the spiral spring.


REFERENCES:
patent: 2850074 (1958-09-01), Silverberg et al.
patent: 4143911 (1979-03-01), Sakakibara et al.
patent: 5383640 (1995-01-01), Johnson et al.
patent: 5765802 (1998-06-01), Bostrom et al.
patent: 5893610 (1999-04-01), Schuler et al.
patent: 5941494 (1999-08-01), Garrido
patent: 5971342 (1999-10-01), Sakai et al.
patent: 6036267 (2000-03-01), Downey
patent: 4241369 (1993-11-01), None

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