Seat belt retractor employing ultrasonic motor

摘要

A reel of a seat belt retractor (20) equipped in a automobile for reeling a seat belt is integral with a shaft (1) of an ultrasonic motor (10). The ultrasonic motor (10) is rotated either one direction or the other so as to retract or draw out the seat belt. A control device (60) for controlling the rotation of the ultrasonic motor (10) by supplying a control signal based on the signals sensed by a buckle sensor (68) which senses a buckle is locked, a tension sensor (63) which senses tension of a seat belt, a speed sensor (64) which senses speed of the automobile, a rotation sensor (62) which senses the rotation degree and a child seat sensor (69) which senses whether child seat is set on a passenger seat. <IMAGE> <IMAGE>