Buckle for a safety belt system provided with a belt pretensioner

Claim 1

A buckle for a safety belt system provided with a belt pretensioner which is effective between said buckle and an anchoring point on the vehicle bodywork or a vehicle seat by moving said buckle towards the anchoring point, said buckle comprising a housing, a guide path for an insert tongue in said housing, a locking bar mounted in said housing for cooperation with a detent opening of the insert tongue, a release button displaceably guided within said buckle, displacement of said release button being parallel to the guide path in said housing and releasing said locking bar from said detent opening on said insert tongue, said release button being movable from a rest position in an actuating direction across a lost motion path before releasing said locking bar, and a locking pawl cooperating with a detent edge on said housing for arresting movement of said release button in the actuating direction prior to release of said locking bar, said locking pawl being biased by biasing means into a position in which said locking pawl does not arrest movement of the release button in said actuating direction, said locking pawl being mounted on said release button, said detent edge on said housing being located at a distance from a pawl tip of said locking pawl along the movement direction of the buckle when the release button is not actuated, said locking pawl being pivotable about a pivot axis, the pivot axis being perpendicular to the movement direction of said buckle in a pretensioning movement, the center of gravity of said locking pawl being offset with respect to the pivot axis of said pawl by an amount such that said locking pawl, under the action of a deceleration of said buckle exceeding a predetermined threshold value, overcomes said biasing means and is moved into engagement with said detent edge to arrest said release button from further movement in said actuating direction.