Pretensioner, seat belt retractor, and seat belt device
View Patent ↗A plurality of driving force transmitting members, a piston, a spring and a gas generator are inserted into the pipe from the end of the pipe where the gas generator is mounted. The gas generator is press-fitted in the pipe while the flat faces thereof are deformed by a pair of protrusions of the pipe. Accordingly, the gas generator is temporarily held by the protrusions of the pipe. Then, one end of the pipe is firmly pressed and the gas generator is mounted in the pipe.
1. A pretensioner, comprising:
a gas generator for generating gas in an event of an emergency;
a piston activated with the gas generated by the gas generator so as to generate driving force;
a plurality of force transmitting members for transmitting the driving force from the piston to a rotational member so as to rotate a spool of a seat belt retractor in a belt retracting direction;
a pipe having a press-fitting portion formed on one end thereof to mount the gas generator, and guiding and housing the piston and the plurality of force transmitting members; and
a spring arranged between the gas generator and the piston in the pipe and urging the piston and the plurality of force transmitting members toward the rotational member;
wherein the pipe has an inner circumferential face, and a temporary joining member formed on the inner circumferential face,
the temporary joining member is a protrusion protruding inwardly from a part of the inner circumferential face between the press-fitting portion and the spring and forming an inner diameter of the pipe thereat, said inner diameter being less than an outer diameter of the gas generator at a position corresponding thereto so that the temporary joining member temporarily holds the gas generator when mounting the gas generator in the pipe, and
the protrusion has an inclined face inclined inwardly in a direction from the press-fitting portion toward the spring such that the gas generator is press-fitted when the gas generator is mounted in the pipe.
2. The pretensioner according to claim 1 , wherein the gas generator has a flat face at a side portion contacting the protrusion, and the protrusion deforms the flat face of the gas generator so as to temporarily hold the gas generator in the pipe.
3. The pretensioner according to claim 2 , wherein the pipe has a flat portion at a side portion adjacent to the protrusion, and the gas generator is positioned relative to the pipe in a rotational direction by contacting the flat face of the gas generator with the flat portion of the pipe.
4. The seat belt retractor, comprising:
the spool for retracting a seat belt;
a locking mechanism activated in the event of the emergency so as to prevent rotation of the spool in a belt withdrawal direction; and
the pretensioner according to claim 1 , the pretensioner being activated in the event of the emergency so as to generate the driving force for rotating the spool in the belt retracting direction.
5. A seat belt device, comprising:
the seat belt retractor according to claim 4 , the seat belt retractor retracting the seat belt;
a tongue slidably supported along the seat belt withdrawn from the seat belt retractor; and
a buckle to which the tongue is detachably latched, wherein the seat belt retractor prevents withdrawal of the seat belt in the event of the emergency so as to restrain an occupant.
6. The pretensioner according to claim 1 , wherein the temporary joining member is a pair of protrusions projecting radially inwardly from the part of the inner circumferential face of the pipe to face each other, and the gas generator has a pair of flat portions formed at side portions thereof facing outwardly in opposite directions so that the pair of protrusions engage the pair of flat portions.
7. A pretensioner, comprising:
a gas generator for generating gas in an event of an emergency;
a piston activated with the gas generated by the gas generator so as to generate driving force;
a plurality of force transmitting members for transmitting the driving force from the piston to a rotational member so as to rotate a spool of a seat belt retractor in a belt retracting direction;
a pipe having a press-fitting portion formed on one end thereof to mount the gas generator, and guiding and housing the piston and the plurality of force transmitting members; and
a spring arranged between the gas generator and the piston in the pipe and urging the piston and the plurality of force transmitting members toward the rotational member;
wherein the pipe has an inner circumferential face, and a temporary joining member formed in the inner circumferential face,
the temporary joining member is a protrusion provided on the inner circumferential face of the pipe between the press-fitting portion and the spring and forming an inner diameter of the pipe thereat, said inner diameter being less than an outer diameter of the gas generator so that the temporary joining member temporarily holds the gas generator when mounting the gas generator in the pipe,
the gas generator has a flat face at a side portion contacting the protrusion, and the protrusion deforms the flat face of the gas generator so as to temporarily hold the gas generator in the pipe,
the pipe has a flat portion at a side portion adjacent to the protrusion, and the gas generator is positioned relative to the pipe in a rotational direction by contacting the flat face of the gas generator with the flat portion of the pipe, and
the gas generator includes: a gas jetting end formed at a front end of the gas generator; a mounting flange portion formed at a rear end of the gas generator to abut against the press-fitting portion of the pipe; and the side portion arranged between the gas jetting end and the mounting flange portion of the gas generator and having a truncated cone-shape portion with respect to the gas jetting end, the side portion of the gas generator having the flat face engaging the side portion of the pipe.
8. The pretensioner according to claim 7 , wherein the pipe includes:
a small diameter portion for housing the spring, the piston, and the plurality of force transmitting members;
a large diameter portion arranged at the one end of the pipe and having the press-fitting portion; and
a medium diameter portion arranged between the small diameter portion and the large diameter portion and having the flat portion.
9. A pretensioner, comprising:
a gas generator for generating gas in an event of an emergency, having a pair of flat surfaces formed at side portions thereof facing outwardly in opposite directions;
a piston activated with the gas generated by the gas generator so as to generate driving force;
a plurality of force transmitting members for transmitting the driving force from the piston to a rotational member so as to rotate a spool of a seat belt retractor in a belt retracting direction;
a pipe having a press-fitting portion formed on one end thereof to mount the gas generator, guiding and housing the piston and the plurality of force transmitting members; and
a spring arranged between the gas generator and the piston in the pipe and urging the piston and the plurality of force transmitting members toward the rotational member;
wherein the pipe has an inner circumferential face, a pair of flat surfaces formed on the inner circumferential face to face each other and engaging the pair of flat surfaces of the gas generator, and temporary joining members protruding inwardly from the pair of flat surfaces of the pipe between the press-fitting portion and the spring, the temporary joining members temporarily holding the gas generator when mounting the gas generator in the pipe, and
each of the temporary joining members has an inclined face inclined inwardly in a direction from the press-fitting portion toward the spring such that the gas generator is press-fitted when the gas generator is mounted in the pipe.