Patent ID: 9688237
Date: 2017-06-27
CPC Classifications: B60R

Claim:
1. A seatbelt retractor comprising: a take-up drum onto which a webbing is wound; a lock mechanism having a lock member that is arranged near one end of the take-up drum and connected to the take-up drum with relative rotation between the take-up drum and the lock member being prohibited, the lock member being prohibited from rotating in a webbing-pull-out direction in case of emergency, and the take-up drum being allowed a relative rotation with respect to the lock member when force to pull out the webbing exceeds a predetermined value in a state that the lock member is prohibited from rotating in the webbing-pull-out direction; an energy absorption mechanism arranged between the take-up drum and the lock member and configured to absorb energy by allowing the relative rotation between the take-up drum and the lock member; and a stopper mechanism configured to stop the relative rotation between the take-up drum and the lock member when the take-up drum is rotated a predetermined number of times relative to the lock member, wherein the lock member includes: wherein the stopper mechanism includes a ring member that (i) is externally fitted and screwed to the fixation boss so as to be allowed relative rotation with respect to the fixation boss, (ii) has an outer peripheral surface fitted in the fitting hole so as to prohibit relative rotation of the ring member and allow the ring member to move in the axial direction of the take-up drum with respect to the fitting hole, and (iii) is movable toward a base end of the fixation boss in the axial direction of the take-up drum by the relative rotation with respect to the fixation boss, wherein when the take-up drum is rotated the predetermined number of times relative to the lock member, the ring member comes into contact with the base end of the fixation boss and is prevented from moving so as to stop the relative rotation between the take-up drum and the lock member, and wherein the base end portion of the fixation boss, including a surface of the base end portion that comes into contact with the ring member, is inside the closed cylindrical portion in the axial direction of the take-up drum and is located radially inward of the lock teeth of the closed cylindrical portion.