Winding device, in particular for a vehicle safety belt

Claim 1

In a device for winding a safety belt, in particular for an automobile vehicle, comprising a fixed housing, a drum which is mounted in the housing to rotate about an axis and to which drum one end of the belt is fixed, at least one elastically yieldable return means for biasing said drum in a belt retraction direction, a shaft mounted to rotate about an axis parallel to the axis of the drum, the return means being disposed between the housing and the shaft, a first pulley integral with the drum, a second pulley integral with the shaft, each pulley having a diameter increasing from one end of the pulley to the other end of the pulley and defining a helical groove, the two pulleys being oriented in opposite directions, and a transmission cable fixed at each of its ends to each one of the pulleys, the elastically yieldable return means being drivingly connected to said shaft; the improvement comprising in combination a means for blocking the drum against rotation, a rotatable cylindrical pulley having an axis parallel to the axis of the drum and around which cylindrical pulley the cable passes in its path between the two pulleys, an input shaft integral with said cylindrical pulley and means responsive to acceleration of said input shaft beyond a threshold value of acceleration for actuating said blocking means whereby said input shaft acceleration is directly proportional to the linear acceleration of the belt.