Patent ID: 6848717

Claim:
A belt tensioner of a seat belt for an occupant on a seat in a vehicle, comprising: a motor switchable between two power ranges; an extraction lock configured to act in response to predetermined parameters; an irreversible tensioning device configured to produce an irreversible tightening of the belt with a strong force to force a desired sitting position of the occupant in response to a crash signal generated by a sensory system; and a retraction device configured to automatically shorten the belt including: (a) a return spring including a retainer remote from the belt and adjustable according to predetermined parameters by the motor; and (b) a normally open clutch arranged parallel to the return spring and configured to one of couple and connect the retainer to the retraction device to connect the retraction device to the motor for a reversible belt tightening in response to a dangerous driving condition, the clutch closable by the motor in accordance with the motor one of rotating in a direction of rotation corresponding to the reversible belt tightening and switching to high power.