Gear unit and motor-driven gear unit for cable window lift systems

Abstract

Gear unit and a motor-driven gear unit for cable window lift systems of motor vehicles, including drive and gear mechanism which cooperates with the drive and is coupled to rotatably mounted cable drum for winding and unwinding cable of the cable window lift system. According to the invention a diameter of the cable drum of the gear unit or motor-driven gear unit is in a range from about 22 mm to about 30 mm, wherein a gear ratio of the gear mechanism ranges from about 1:38 to about 1:55. A cable drum has, on its end side, claws which engage in correspondingly designed recesses on the end side of a worm wheel. Electric motors having a maximum driving torque of only about 5.7 Nm can be used. Overall, the size of the gear unit or motor-driven gear unit can be reduced by about 40-50%.

Description

FIELD OF INVENTION [0001] The present invention relates to a gear unit and to a motor-driven gear unit for cable window lift systems of motor vehicles. RELATED ART [0002] The many requirements on motor-driven gear units for cable window lift systems in motor vehicles mean in practice relatively narrow parameter ranges in terms of the structural design. In particular, the following constraints must be taken into account in the structural design: the output power of the electric motor used for the electric drive; the available on-board power of motor vehicles, which has an effect on the maximum output power; the friction forces brought about by the structural design of the window lift system, which predefine the necessary minimum output power; the structural design both for window lift systems of motor vehicle front doors and also for window lift systems of motor vehicle rear doors; the required maximum travel for adjusting the window; the expected maximum number of actuations of the ...

AI Technical Summary

Benefits of technology

The present invention provides a gear unit for cable window lift systems of motor vehicles that can be used for both rear and front cable window lift systems. The gear unit is designed with a smaller diameter cable drum and a reduced gear ratio, which allows for the use of smaller power motors. The gear unit is simple in design, cost-effective, and can be sealed in a more simplified manner compared to previous designs. The cable drum can be coupled directly to the worm wheel, allowing for a manual or electric drive without further design modifications. The invention thus provides a versatile and cost-effective solution for cable window lift systems in motor vehicles.

Problems solved by technology

In practice, these requirements have led to window lift system drives with worm wheel reduction always having a gear ratio in the range from about 1:62 to about 1:84, wherein the cable drums always have a diameter in the range from about 36 mm to about 48 mm and the output power of the electric motors always is about 20 W. Deviations from these relatively narrow parameter ranges are in practice very difficult since in any modification a large number of conditions have to be optimized, as mentioned above.

Some of the abovementioned parameters and also other parameters can rarely be changed in practice because serious technical problems would arise.

For example, a possible reduction in the diameter of the cable drum entails the disadvantages that the cable winds up relatively high on the drum, which poses great problems in terms of cable guidance and also the structural design of cable window lift systems, and that the cable is bent to a considerably greater extent, which adversely affects the durability of the cable which is to be ensured throughout the entire service life of the motor vehicle.

In particular, the fact that for this reason electric cable window lift systems both for the front door and for the rear door are nowadays provided as a unit with electric motors having a possible output power of 20 W nevertheless has the disadvantage that too great a structural volume has to be provided in the rear door, which is actually not necessary.

However, the comparatively high requirements in terms of adjusting a front window, particularly relatively complex window guides with a poorer mechanical efficiency and the like, prevent this.

The multi-part design of the driven train, comprising the driven pawl, the deformable rubber damping elements connected to the pawl—which engage in a form-fitting manner in corresponding retaining ribs in the inner periphery of the worm wheel—and the worm wheel, is comparatively complex and expensive.

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