Reversible seat belt tensioner

Abstract

A reversible seat belt tensioner includes an electric motor (2), a belt shaft (1) drivable in the belt winding direction by the electric motor (2) via a drive wheel (10), and a drive shaft (9) transmitting the rotational movement of the electric motor (2) to the drive wheel (10). The drive shaft (9) is connected to at least one of the drive wheel (10) and the electric motor (2) via a helical gear unit. The teeth of the helical gear unit make point-shaped contacts with each other, and the drive shaft (9) is axially movable relative to the electric motor (2) or the drive wheel (10) without disengaging the gear teeth.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a Continuation of U.S. patent application Ser. No. 13 / 060,480, entitled “REVERSIBLE SEAT BELT TENSIONER,” which claims priority to German Patent Application 10 2008 048 339.7, filed Sep. 22, 2008, and International Patent Application No. PCT / EP2009 / 006287, filed Aug. 31, 2009.TECHNICAL FIELD OF THE INVENTION[0002]The invention relates to a reversible seat belt tensioner comprising an electric motor, a belt shaft drivable in the belt winding direction by the electric motor via a drive wheel, and a drive shaft transmitting the rotational movement of the electric motor to the drive wheel.BACKGROUND OF THE INVENTION[0003]From WO 2003 / 099619 A2, a reversible seat belt tensioner is known wherein the drive shaft transmitting the rotational movement of the electric motor to the belt shaft is coupled to the electric motor via a crown gear unit and is coupled to the drive wheel via a worm gear unit.[0004]A disadvantage in this e...

AI Technical Summary

Benefits of technology

The invention provides a reversible seat belt tensioner that can be arranged in different orientations, making it more compact and easier to install. It also reduces noise during tensioning. This is achieved by using a helical gear unit that allows for the arrangement of rotating parts at angles with each other, and by designing helix angles that can change the transmission ratio. This reduces the need for high production accuracy requirements and reduces effort and costs.

Problems solved by technology

A disadvantage in this embodiment is that the arrangement of the components with respect to each other cannot be freely chosen, as the gear wheels of the gear units deflect the rotational movement by 90 degrees each, and, therefore, the rotational axes of the meshing rotating components have to be arranged at an angle of 90 degrees with respect to each other.

It has further turned out that the noises developing in the crown gear unit and in the worm gear unit during the seat belt tensioning, in particular for vehicles of the higher quality class, are no longer tolerated by the vehicle manufacturers.

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