JPH10297426A - Load limiter for seat belt retractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load limiter, by which an impact toward an occupant chest part can be reduced in an occupant chest part mobile locking initial stage and an impact energy absorbing quantity can be increased in case of a vehicle collision, for a seat belt retractor. SOLUTION: When a load limiter is operated, that is, when a wire winding reel 3 is rotated integrally with a spool shaft 1 and a wire 20 is wound up, a large diameter part 21 of the wire 20 is ironed by means of a wire ironing part 22, so that high frictional resistance is obtained. After the large diameter part 21 passes, the frictional resistance is lowered. Consequently, occupant locking force in an occupant chest part mobile locking initial stage is increased while an occupant locking force is reduced along a moving stroke, so that ideal occupant locking is carried out. At the same time, an impact energy absorbing quantity can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load limiter for a seat belt retractor used for a vehicle such as an automobile.

[0002]

2. Description of the Related Art It is desired that a seat belt retractor for a vehicle be capable of optimally restraining an occupant by restraining the occupant when the occupant is restrained, even if the seat belt is slack due to clothing or the like of the occupant. Therefore, the seat belt retractor operates by receiving an operation signal at the time of a vehicle collision, rotates the spool in the belt winding direction, removes the seat belt slack, and applies a pretension to the seat belt. In some cases, a pretensioner is provided.

[0003] Even in a seat belt retractor provided with such a pretensioner, a retractor lock mechanism that locks based on a detection signal of a collision sensor at the time of a collision of the vehicle has a problem that the seat belt is slightly moved due to the inertia of the occupant after the lock operation. Only after the amount is withdrawn, the rotation of the spool is locked, that is, the pull-out of the seat belt is locked. For example, as shown in page 4-29 of the new model manual issued by Toyota Motor Corporation in 1996. Before the retractor lock mechanism is locked and the rotation of the spool is locked, a load limiter device is provided to apply resistance to pulling out the seat belt and reduce an impact given to the occupant's chest. ing.

In this load limiter device, a pawl provided on a spool shaft is interlocked with a locking operation of a retractor lock mechanism, and the pawl is connected to a gear on the inner periphery of a wire take-up reel arranged concentrically with the spool shaft in a retractor housing. Meshing, transmitting the pull-out load (belt tension) of the seat belt to the wire take-up reel,
By shearing the shear pin fixing the wire take-up reel, the wire take-up reel is rotated to take up the wire drawn from the wire housing, and a wire ironing device provided on the wire housing in the wire take-up process. By squeezing the wire at the part, frictional resistance is generated to absorb the belt tension, and to reduce the impact given to the occupant's chest.

[0005]

Since the wire diameter of the wire is constant, the frictional resistance value generated at the wire ironing portion, that is, the wire ironing load becomes constant. As shown by the line b in FIG. 5, the belt tension that can be absorbed by the wire ironing at a certain stroke point in the initial stage of the occupant chest movement constraint from the operation start point of the load limiter device, that is, the occupant restraining force becomes a constant value. It will be suppressed.

Accordingly, the present invention temporarily increases the occupant restraining force in the early stage of restraining the occupant's chest movement, and gradually reduces the restraining force to ideally restrain the occupant's chest from moving, thereby relaxing the impact. It is an object of the present invention to provide a load limiter device for a seat belt retractor that can increase the amount of impact energy absorption and further improve safety.

[0007]

According to a first aspect of the present invention, a gear is provided on an inner periphery, is disposed concentrically with a spool shaft in a retractor housing, and rotates with respect to a load in a rotational direction exceeding a predetermined value. A wire take-up reel that is attached to the gear, a pawl that meshes with the gear at the time of locking operation of the retractor lock mechanism, and transmits a belt tension acting on the spool to the wire take-up reel, and a wire housing fixed to the retractor housing. A wire which is pulled out and is hung on a wire ironing part provided in the wire housing, and an end of which is retained on the wire winding reel. Characterized in that a large diameter portion for increasing the wire ironing load is provided.

According to a second aspect of the present invention, the large diameter portion of the wire according to the first aspect is formed in a tapered shape having a smaller diameter from the wire ironing portion to the rear.

A third aspect of the present invention is characterized in that the large diameter portion of the wire according to the first or second aspect is formed by spirally winding a wire member around the outer periphery of the wire.

[0010]

According to the first aspect, at the initial stage of operation of the load limiter device, that is, at the initial stage of winding the wire, the large diameter portion of the wire is squeezed by the wire squeezing portion, so that the wire squeezing load is large. After the locking operation of the retractor locking mechanism and the rotation of the spool are locked, the occupant restraining force in the initial stage of restraining the occupant's chest movement by the seat belt is temporarily increased, and after the large diameter portion has passed the wire ironing portion, Since the occupant restraining force gradually decreases, the movement of the occupant's chest can be ensured, and the impact can be mitigated and ideally restrained, and the amount of impact energy absorbed can be increased, further improving safety. can do.

According to the second aspect, in addition to the effect of the first aspect, the large diameter portion of the wire is formed in a tapered shape having a small diameter toward the rear of the wire ironing portion. Can be reduced by the liner, and the impact on the occupant's chest can be reduced more ideally.

According to the third aspect, in addition to the effects of the first and second aspects, the large-diameter portion of the wire is formed by spirally winding and fixing a linear member on the outer periphery of the wire. The portion can be easily formed, and can be advantageously obtained in terms of cost.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 3, reference numeral 1 denotes a retractor housing for a seat belt retractor. The retractor housing 1 is formed in a flat U-shape, and a wire take-up reel 3 described later is mounted on both side walls 1A. Mounting holes 2 are formed.

Reference numeral 3 denotes a ring-shaped wire take-up reel, which is fitted to the peripheral edge of the mounting hole 2 via an annular groove 4 on the outer periphery and is concentric with a spool shaft 11 having a seat belt end (not shown). It is arranged.

The wire take-up reel 3 has a reel groove 5 on one side edge inside the retractor housing 1 and a gear 6 formed on the inner periphery. The shear pin 7 is fixed to the side wall 1A by a plurality of shear pins 7, and when a load equal to or more than a predetermined value acts in the rotation direction, the shear pin 7 is sheared and can be rotated.

The reel groove 5 of the wire take-up reel 3
A notch 8 is partially formed in the portion where the notch 8 is formed. A stopper 9 and a wire stopper 10 are provided adjacent to the portion where the notch 8 is formed, and an end of a wire 20 described later is connected to the notch 8. 8
Through the stopper 9 and the wire stopper 10,
The end of the wire 20 is made to stay.

On the other hand, a pawl 12 meshing with the gear 6 of the wire take-up reel 3 is connected to a pin 13 of the spool shaft 11 in conjunction with a locking operation of a retractor lock mechanism (not shown).
The pawl 12 meshes with the gear 6 to transmit the pullout load (belt tension) of the seat belt to the wire take-up reel 3 as a rotational load.

A stopper plate 14 for restricting the rotation of the wire take-up reel 3 by engaging a stopper 9 of the wire take-up reel 3 with an inner surface of the back wall 1B of the retractor housing 1 by a caulking pin 15. It is fixed by swaging.

A wire housing 16 is fitted to and fixed to the back wall 1B below the stopper plate 14 through a boss 17 projecting from the back of the stopper plate 14 and a boss fitting hole 18 of the back wall 1B. At the same time, the end face of the boss portion 19a of the wire bobbin 19 of the wire housing 16 abuts against the side wall 1A and is fastened and fixed by a screw 24.

In the wire bobbin 19, a wire 20 is wound around a boss portion 19a and housed. The wire 20 has a projection 22a raised on a lower flange connected to the bottom of the wire bobbin 19; And a roller 22b rotatably supported on the side wall of the wire housing 16 adjacent to the wire 22a and pulled out in an S-shape around a wire ironing portion 22 composed of a roller 22b. It is frequent.

Then, a wire ironing load (friction resistance) at the wire ironing portion at the initial stage of winding the wire is applied to a portion of the wire 20 suspended on the wire ironing portion 22.
Is formed.

The large diameter portion 21 is formed in a tapered shape having a smaller diameter toward the rear of the wire ironing portion 22, that is, toward the wire bobbin 18.

According to the structure of the above-described embodiment, when a retractor lock mechanism (not shown) locks during a frontal collision of the vehicle, the spool shaft 11 is interlocked with this lock operation.
Is rotated and meshes with the gear 6 of the wire take-up reel 3.

The spool (not shown), which is fitted around the spool shaft 11 and winds up the seat belt, is not drawn until the seat belt is pulled out a little by the inertial movement of the occupant after the locking operation of the retractor lock mechanism. Although the rotation is locked, the pull-out load (belt tension) of the seat belt after the locking operation of the retractor lock mechanism is immediately applied to the pawl 1 from the spool shaft 11.
The load is transmitted as a rotational load to the wire take-up reel 3 via the shaft 2, and when this load exceeds a predetermined value, the shear pin 7 is sheared, and the wire take-up reel 3 is integrated with the spool shaft 11 in the seat belt withdrawing direction. To rotate.

When the wire 20 is wound along the reel groove 5 by the rotation of the wire take-up reel 3, the wire 20 is pulled out from the wire bobbin 19 while being squeezed by the wire squeezing portion 22. In the initial stage of the removal, the large-diameter portion 21 of the wire 20 is squeezed by the wire squeezing portion 22 to cause the wire squeezing load (friction resistance).
Therefore, the occupant restraining force at the initial stage of restraining the occupant's chest movement by the seat belt from the locking operation of the retractor locking mechanism to the locking of the spool is shown in FIG.
When the large diameter portion 21 passes through the wire wrought portion 22 and the general portion of the wire 20 is squeezed by the wire squeezed portion 22 as shown by the line a in the characteristic diagram of FIG. Therefore, the movement of the occupant's chest can be surely restrained, and the shock can be moderated to ideally restrain the movement.

Further, since the occupant restraining force in the initial stage of restraining the occupant's chest movement is increased, the amount of impact energy absorbed can be increased and safety can be further improved.

Particularly in the present embodiment, the large-diameter portion 21 of the wire 20 is formed in a tapered shape having a smaller diameter toward the rear of the wire ironing portion 22, so that the occupant restraining force can be reduced linearly. Can be performed, and the impact on the occupant's chest can be reduced more ideally.

FIG. 4 shows a different example of the large diameter portion 21 of the wire 20. In this embodiment, a wire member 23 made of the same material as the wire 20, for example, is spirally wound around the outer periphery of the wire 20. The large diameter portion 21 is formed by being fixed.

In this embodiment, since the large-diameter portion 21 can be formed by winding and fixing the wire member 23 around the outer periphery of the wire 20, the wire 20 itself has the same wire diameter as in the conventional case. In addition, since the wire member 23 can be easily spirally wound and fixed to the wire 20, the large-diameter portion 21 can be easily formed at an arbitrary portion of the wire 20, which is advantageous in cost. Obtainable.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the embodiment.

FIG. 3 is an enlarged view showing a large-diameter portion of the wire according to the embodiment.

FIG. 4 is an enlarged view showing a different example of a large diameter portion of a wire.

FIG. 5 is an impact energy absorption characteristic diagram of the load limiter device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 retractor housing 3 wire take-up reel 6 gear 11 spool shaft 12 pawl 16 wire housing 20 wire 21 large diameter portion 22 wire ironing portion 23 linear member

Claims (3)

[Claims] 1. A retractor lock having a gear on the inner periphery, disposed concentrically with a spool shaft in a retractor housing, and rotatably attached to a load in a rotational direction of a predetermined value or more, and a retractor lock. A pawl that meshes with the gear when the mechanism is locked to transmit the belt tension acting on the spool to the wire take-up reel, and a wire squeezing portion provided on the wire housing that is pulled out from the wire housing fixed to the retractor housing. And a wire having an end portion suspended on the wire take-up reel. A load limiter for a seat belt retractor. 2. The load limiter device for a seat belt retractor according to claim 1, wherein the large-diameter portion of the wire is formed in a tapered shape having a smaller diameter from the wire ironing portion toward the rear. 3. A load limiter device for a seat belt retractor according to claim 1, wherein the large diameter portion of the wire is formed by spirally winding and fixing a linear member around the wire.