JP2002046576A - Seat belt device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an initial restraint effect by a seat belt webbing. SOLUTION: In the webbing 11, metal impact absorbing members 20, 21 are respectively provided to three parts. At the time of impact, when a load is applied to the webbing 11, the impact absorbing members 20, 21 are extend and deformed so as to exceed a yield point, whereby an impact energy of an occupant is absorbed. Accordingly, the initial restrain effect of the occupant by the webbing 11 is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a seat belt device.

[0002]

2. Description of the Related Art FIG. 11 shows characteristics of an occupant restraint in a collision by a conventional seat belt device. In the same drawing, a broken line S1 indicates a state in which the occupant is restrained only by the seat belt webbing, the vertical axis indicates the force transmitted from the webbing to the occupant's chest, and the horizontal axis indicates the moving amount of the occupant's chest. Since the webbing is loosened when worn on the body, the occupant must move forward to some extent during the collision (L
(Position 1) Restraining by webbing is started.
When the restraint is started, the webbing elastically expands with the movement of the occupant, and the load applied to the body from the webbing also increases. Then, when the occupant stops moving forward, the load received by the chest from the webbing also reaches a peak.

As described above, in the restraint using only the webbing, the timing at which the restraint of the occupant is started after the collision is late, and the peak value of the load received by the occupant from the webbing tends to increase. Therefore, in recent seat belt devices, these problems are solved by providing a pretensioner mechanism and a force limiter mechanism in the retractor.

[0004] A solid line S2 in FIG. 11 shows the characteristics of occupant restraint by such a seat belt device. When detecting the collision, the pretensioner mechanism instantaneously rolls up the webbing to bring the webbing into close contact with the occupant. Then, when the webbing lock is actuated and the webbing unreeling is stopped,
The restraint of the occupant is started earlier (the position of L2). On the other hand, when the specified load Fc is applied to the webbing, the force limiter mechanism feeds out the webbing so that the load applied to the occupant is not further increased.

[0005]

However, in the above-described seat belt device, the restraining force by the webbing is relatively small immediately after the pretensioner operates and restraint is started, so that the restraining effect can be efficiently achieved. I can't show it. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a seat belt device capable of enhancing an initial restraint effect by seat belt webbing.

[0006]

According to a first aspect of the present invention, there is provided a seat belt device made of a metal having a characteristic of extending and deforming beyond a yield point by a tensile load of a webbing at the time of a collision. Is characterized in that the shock absorbing member is mounted in parallel with the webbing in the direction in which the webbing extends.

According to a second aspect of the present invention, in the first aspect, a reduced portion having a cross-sectional area orthogonal to the extension direction smaller than other portions is formed in a part of the shock absorbing member. Has features.

[0008]

According to the first aspect of the present invention, when a load is applied to the webbing at the time of a collision, the shock absorbing member expands and deforms together with the webbing, and deforms beyond the yield point, so that the collision energy of the occupant is reduced. Is absorbed. This makes it possible to improve the effect of the occupant being initially restrained by the webbing.

According to the second aspect of the present invention, by providing a reduced portion having a small cross-sectional area in a part of the shock absorbing member, stress concentrates near the reduced portion. For this reason, the deformation exceeding the yield point appears more prominently in the vicinity of the reduced portion than in other portions, and the shape in the vicinity of the reduced portion greatly affects the elongation characteristics of the entire shock absorbing member. Therefore, when designing a shock absorbing member having desired elongation characteristics, it is only necessary to appropriately change the shape and the like in the vicinity of the reduced portion, and the design can be easily performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a three-point seat belt device 10 of the present embodiment.
The webbing 11 is woven from, for example, polyester fiber or the like, and has a property of being substantially elastically stretched when a tensile force is applied. On one side of the seat S, an outer-side fitting 12 is attached to the floor of the vehicle body, and one end of the webbing 11 is fixed thereto. In addition, a shock absorbing member 21 described later is attached to a connection portion between the webbing 11 and the outer-side attachment 12. On the other side of the seat S, an inner mounting 13 is attached to the floor of the vehicle body, to which a tongue plate 15 passed through the webbing 11 can be connected. Further, a shoulder anchor 16 is provided on the side opposite to the seat S, and on the upper part of the vehicle body (not shown), and the webbing 11 is stretched over the shoulder anchor 16. The webbing 11 extends downward from the shoulder anchor 16,
Its end is connected to a retractor (not shown) provided at the lower part of the vehicle body, and is constantly urged in the winding direction. The retractor is equipped with a well-known pretensioner mechanism, a lock mechanism, and a force limiter mechanism. When the pretensioner mechanism detects a collision,
It acts to wind up the webbing 11 instantaneously. Also,
The locking mechanism locks the webbing 11 when the webbing 11 is suddenly pulled out, and stops feeding. Further, the force limiter mechanism operates to extend the webbing 11 when a prescribed tensile load is applied to the webbing 11 after the webbing 11 is locked.

The webbing 11 has a pair of shock absorbing members 20 and 21 at a total of three locations.
Among them, the outer side fixture 12 to the tongue plate 15
And a pair of shock absorbing members 20 attached in the middle of
As shown in FIGS. 2 and 3, the webbing 11 is formed of a substantially rectangular metal plate, and the webbing 11 is sandwiched therebetween, and the length direction of the webbing 11 coincides with the length direction (that is, the extension direction) of the webbing 11. The two ends are fixed with a pair of fasteners 23 respectively. In the center of each shock absorbing member 20 in the length direction, a rhombic opening 2 penetrating in the thickness direction is provided.
4 are provided. Both side portions of the opening 24 are reduced portions 25, and the cross-sectional area orthogonal to the length direction is smaller than other portions. In addition, in the webbing 11,
A pair of similarly-shaped impact absorbing members 20 are also attached to a position below the shoulder anchor 16.

Further, the webbing 11 and the outer side fixture 1
As shown in FIG. 4, a pair of shock absorbing members 21 are attached to a connection portion between the two. These shock absorbing members 21 have substantially the same structure except that they are slightly larger in size than the shock absorbing members 20, and are formed of a substantially rectangular metal plate. One end in the length direction of the shock absorbing member 21 is attached to the webbing 11 by a pair of fasteners 26, and the other end is attached to the outer-side attachment 12. Further, a rhombic opening 27 is provided at the center of each shock absorbing member 21, and both sides thereof are reduced portions 28.

Now, each of the shock absorbing members 20, 21 is
It has an elongation characteristic as shown in FIG. 5, for example, with respect to a tensile load. When a tensile load is applied to each of the shock absorbing members 20 and 21, the load suddenly increases with respect to the amount of elongation in the initial stage, and then becomes slightly gentle, reaches the yield point Y, and exceeds the yield point Y. Then, the load gradually decreases.

Next, effects of the present embodiment will be described. In the present embodiment, the webbing 11 and the shock absorbing members 20 and 21 are used.
By arranging in parallel, the so-called parallel spring principle is applied. That is, as shown in FIG. 6, the total elongation modulus K is equal to kw + ks obtained by adding the elongation modulus kw of the webbing and the elongation modulus ks of the shock absorbing member. A solid line S3 in FIG. 7 shows an example of the characteristics of the seat belt device 10 of the present embodiment, in which the vertical axis represents the load transmitted from the webbing to the occupant's chest, and the horizontal axis represents the movement amount of the occupant's chest. I have. Note that the broken line S2 in the figure shows the same characteristic of the seat belt device as that shown in FIG. 11 of the conventional example for comparison.

After the collision, when the pretensioner is operated, the slack of the webbing 11 is taken up, the webbing 11 comes into close contact with the occupant's body, and the webbing 11 is locked by the lock mechanism to stop the feeding. Webbing 1
In FIG. 1, since the shock absorbing members 20 and 21 are attached in parallel with the direction of extension, the elongation and deformation characteristics thereof are obtained by adding the elongation and deformation characteristics of the respective shock absorbing members 20 and 21 to those of the webbing 11 itself. It has become. Therefore, when the restraint by the webbing 11 is started, the occupant receives a larger load on the chest than in the case of the conventional webbing 11 alone. And as the chest moves forward, webbing 11
At the same time, each of the shock absorbing members 20 and 21 expands and deforms, and reaches the yield point Y. When each of the shock absorbing members 20 and 21 exceeds the yield point Y, the load applied to the shock absorbing members 20 and 21 gradually decreases, and the load applied to the webbing 11 side arranged in parallel with the shock absorbing members 20 and 21 increases. Therefore, as shown in FIG. 7, the characteristics of the seat belt device 10 change stepwise. Then, when the load applied to the webbing 11 reaches a specified value (here, Fc2) of the force limiter mechanism, the locked webbing 11 is fed out, and a further increase in the load is suppressed. When all the collision energy of the occupant's body is absorbed, the movement of the chest stops (the position indicated by L3).

As described above, by attaching the shock absorbing members 20 and 21 to the webbing 11, the initial restraint is effectively performed. In the above, an example was given in which the prescribed value Fc2 of the force limiter was made lower than before so as to lower the maximum value of the load applied to the occupant. For example, the maximum movement amount (L3) of the chest may be reduced. It becomes possible.

Further, by providing the reduced portions 25 and 28 having a small cross-sectional area in a part of the shock absorbing members 20 and 21, stress is concentrated near the reduced portions 25 and 28 when a tensile force acts. For this reason, the deformation exceeding the yield point appears more prominently in the vicinity of the reduced portions 25 and 28 than in other portions, and the shape in the vicinity of the reduced portions 25 and 28 greatly affects the elongation characteristics of the entire shock absorbing members 20 and 21. Will have an effect. Therefore, when designing a shock absorbing member having desired elongation characteristics,
The shape and the like in the vicinity of the reduced portion may be appropriately changed (for example, in the case of the above, the openings 24 and 27 are enlarged or reduced in the length direction or the width direction), and design can be easily performed.

<Other Embodiments> The technical scope of the present invention is as follows.
The present invention is not limited to the embodiments described above, and for example, the following ones are also included in the technical scope of the present invention. (1) Although the seat belt device 10 of the above embodiment is of a three-point type, the present invention is also applicable to a two-point type and other types of seat belt devices. (2) In the above-described embodiment, an example is shown in which the impact absorbing members 20 and 21 are attached to the webbing 11 at three locations, one pair at a time.
The number of attachments is not limited to the above. (3) The shape of the shock absorbing member may be, for example, a shape shown by 30, 31, or 32 in FIGS. Each of 33, 34, and 35 is a reduced portion, and has a smaller cross-sectional area than other portions. Further, shapes other than those described above may be used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a seat belt device according to an embodiment.

FIG. 2 is a plan view showing a shock absorbing member.

FIG. 3 is a side view of the shock absorbing member.

FIG. 4 is a plan view showing another shock absorbing member.

FIG. 5 is a load-elongation characteristic diagram of the shock absorbing member.

FIG. 6 is a diagram showing the principle of a parallel spring.

FIG. 7 is a load-movement amount characteristic diagram of the seat belt device.

FIG. 8 is a plan view showing another shock absorbing member.

FIG. 9 is a plan view showing another shock absorbing member.

FIG. 10 is a plan view showing another shock absorbing member.

FIG. 11 is a characteristic diagram of load-movement amount of a conventional seat belt device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Seat belt device 11 ... Webbing 20, 21, 30, 31, 32 ... Shock absorbing member 25, 28 ... Reduction part Y ... Yield point

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimihiro Ouchi 77-1 Shimohoike, Yoshiwara-cho, Toyota-shi, Aichi F-term (reference) in Knox Electronics Co., Ltd. 3D018 BA05 BA14 DA02 DA05

Claims (2)

[Claims] 1. A metal shock absorbing member having a characteristic of extending and deforming beyond a yield point by a tensile load of a webbing at the time of a collision is attached to said webbing in parallel in the direction of extension. Seat belt device. 2. The seat belt device according to claim 1, wherein a reduced portion having a cross-sectional area orthogonal to the extension direction smaller than other portions is formed in a part of the shock absorbing member.