Patent ID: 8123154
Filing Date: 2012-02-28
Classification: B60R

Abstract:
1. A seat belt retractor for motor vehicles having a belt shaft and a housing, said retractor comprising: a two-stage force limiting device having two force limiting elements connected in series, the force limiting elements being switchable between a high level and a low level of force limitation via an interposed coupling that is controlled by means of a control device for switching the coupling between the high level and the low level of force limitation, said control device comprising a counter gear mechanism which determines an amount of belt webbing that is extended from the belt shaft, the coupling being reversibly switchable between the high and the low levels of force limitation, the counter gear mechanism comprising a first externally toothed gear wheel rotatably connected to the belt shaft, a second externally toothed gear wheel rotatably connected to the housing, and a third externally toothed gear wheel rotatably connected to a rocker arm pivotably mounted on the housing and pivotable between two switching positions, wherein the third gear wheel meshes with the first and with the second toothed gear wheels, the first and third gear wheels comprising a first pair of interacting switching lugs, and the second and third gear comprising a second pair of interacting switching lugs, wherein the switching lugs of each pair come into contact with each other in a respective unwinding state and pivot the rocker arm into one of the two switching positions; a first catch directly controlled by the rocker arm via a mechanical connection; a second catch being a control catch positioned on the first catch relatively displaceably thereto and interacting with the rocker arm, the second catch having a control coq that interacts with an outer gearing of a toothed ring; the first catch having a release position in which the first catch is pretensioned relative to the toothed ring by means of a first spring; the second catch having a holding position and a release position and being biased by a pretensioned second spring in a direction of engagement in the outer gearing of the toothed ring, the second spring being fixed in the release position of the second catch relative to the toothed ring by means of a separately controlled holding device which releases the second spring when the second catch engages in the outer gearing of the toothed ring.