Pretensioner, seat belt retractor having the same, and seat belt apparatus provided therewith

Abstract

In order to improve piston sealing performance and thereby prevent reactive gas from losing gas pressure wherever possible, a piston (11) has an expanding section (11a) formed at one end thereof contacting a force transmission component (10). When gas pressure resulting from reactive gas generated by a gas generator (13) causes the piston (11) to exert a pressing force on the force transmission component (10) in the event of an emergency, the expanding section (11a) expands toward the inner circumferential surface (9a) of a pipe (9) due to the gas pressure. As a result, the outer circumferential surface 11a 1 of the expanding section (11a) in the piston (11) comes into contact with the inner circumferential surface (9a) of the pipe (9) in a more efficient manner, resulting in enhanced sealing between the piston (11) and the inner circumferential surface (9a) of the pipe. This prevents reactive gas from losing gas pressure, thereby allowing the gas pressure to more efficiently act on the piston (11).

Description

technical field [0001] The present invention relates to the technical field of a pretensioner that improves the binding force of a seat belt to an occupant by using reactive gas to rotate the reel of a seat belt retractor in the direction of seat belt winding at the initial stage of an emergency such as a vehicle collision, and the safety of winding. The technical field of a belt retractor and the technical field of a vehicle seat belt device. Background technique [0002] Conventionally, various seat belt retractors equipped with pretensioners have been developed for seat belt devices installed in vehicles such as automobiles. In this pretensioner, at the initial stage of an emergency when a deceleration greater than the normal deceleration is applied to the vehicle, such as when the vehicle is collided, the reel of the seat belt retractor is wound toward the seat belt by the reaction gas generated by the gas generator. direction rotation, the seat belt is wound by the ree...

AI Technical Summary

Problems solved by technology

[0010] However, if Figure 5 As shown in (a), since the piston d of the pretensioner a described in Patent Document 1 is formed of a ball, a relatively large gap r is generated between the piston d and the force transmission member c that is in contact with the piston d. , and forms the inner wall b of the conduit b that is difficult to be attached to the piston d when the piston d moves to press the force transmission member c 4 The shape of the direction deformation

Therefore, the sealing performance of the piston d is insufficient, the gas pressure loss of the reaction gas generated by the gas generator f occurs, and the gas pressure of the reaction gas cannot be effectively used for the force transmission member c.

[0011] In addition, if Figure 5 As shown in (b), similarly, in the cylindrical piston d described in Patent Document 2, the same gas pressure loss of the reaction gas as in the pretensioner a described in Patent Document 1 occurs

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