Pretensioning safety belt apparatus

摘要

A length of shoulder belt webbing is extensible around the torso of a vehicle occupant to restrain forward movement of the vehicle occupant in the vehicle. A webbing guide guides the belt webbing around the body of the vehicle occupant. In response to vehicle deceleration at a rate above a predetermined rate, a pyrotechnic charge directs gas under pressure into an expansible chamber to move the webbing guide upward on the vehicle to tension belt webbing extending through the webbing guide. A gas outlet enables controlled flow of gas out of the expansible chamber to allow controlled downward movement of the webbing guide under tension in the belt webbing resulting from forward movement of the vehicle occupant subsequent to upward movement of the webbing guide. The webbing guide may be height adjustable by the vehicle occupant. The pyrotechnic charge may be connected with the webbing guide for movement with the webbing guide.