The invention relates to a longitudinal seat adjustment device.
Longitudinal seat adjustments generally have a lower rail fixed to a chassis, inside which lower rail and upper rail, to which the seat is attached, can be propelled by motor. A spindle fixed by its respective ends to the lower rail sits inside the upper rail, on which spindle a transmission fixedly coupled to the upper rail is arranged in axially movable fashion. The seat, which is located on the two upper rails arranged parallel to one another, can be propelled via a motor device that sits between the rails.
Examples of devices for the purpose of longitudinal seat adjustments have been disclosed in DE 36 40 197 A1, DE 42 08 948 C2, DE 196 42 655 C2, DE 198 15 283 A1, DE 198 44 817 A1, DE 199 44 690 A1, and WO 95/16 585. There is a need for a compact longitudinal seat adjusting device in which only a few components are needed and that can without difficulty accommodate the forces that occur especially in the case of a crash, and in particular for a transmission that transforms the rotational motion of the drive motor into a translational motion.
A further goal of the present invention is for the space occupied by the longitudinal seat adjusting device to be relatively small, preferably only 15 mm in width. Moreover, the permissible protrusion of the upper rail is likewise not to be too great, at most some 15 mm. Finally, the device according to the invention is to satisfy a strength requirement in both directions, which is for example 25000 N.
Finally, the device according to the invention is to be relatively rapidly adjustable, that is, for example at between 15 and 25 mm/s over a relatively long adjustment range of for example 300 mm.