| 摘要 |
PURPOSE: To provide a belt retractor for a vehicular seat belt with a rotational belt tensioner drive engaged with a belt reel, which attains more compact structure advantageously using an available gas generator and providing a large tensioning stroke. CONSTITUTION: A speed-up planetary gear device is arranged between a belt tensioner drive 12 and a belt reel 16. The speed-up planetary gear device has a ring gear 30 with an internal teeth, a planetary gear 28, a planetary carrier, and a sun gear 26. The planetary gear 28 is engaged with the internal teeth of the ring gear and an external teeth of the sun gear 26. The belt tensioner drive 12 has a driving part united to the ring gear 30 so as to drive, and the sun gear 26 can connected to the belt reel 16 so as to drive, and the planetary carrier is fixed to a retractor housing. The driving part is formed by a rotary piston 301 of a rotary piston rotationally drive having a gas generator 36. |
