Elektromotorischer Stelltrieb für verstellbare Aggregate an einem Kraftfahrzeug

摘要

A motor-vehicle power actuator has a housing, an electric motor in the housing having an output shaft, an input gear fixed on the shaft, a threaded spindle extending along and rotatable about a spindle axis in the housing, an output gear fixed on the spindle adjacent and out of contact with the input gear, and a nut threaded on the spindle and nonrotatable relative thereto. Thus rotation of the spindle in one rotational sense displaces the nut axially relative to the spindle axis in a release direction. A rocker pivotal in the housing on the shaft axis carries an intermediate gear meshing with the input gear, and also meshable with the output gear. The rocker is pivotal between an end position in which the intermediate gear meshes with the output gear and through an intermediate position in which the intermediate gear does not mesh with the output gear. The rocker and intermediate gear are so positioned that, on normal forward rotation of the motor shaft, the rocker moves into its end position. A biasing unit urges the rocker into the intermediate position except when the motor is energized and is rotatably driving its shaft and a spring unit engaged between the housing and the nut axially biases the nut in one of the directions so that when the motor is not actuated the biasing unit disconnects the input and intermediate gears from the output gear and the spring unit urges the nut in the one direction.