JPH0717351A - Bag body for air bag device - Google Patents

Abstract

PURPOSE:To surely absorb the collision energy of a driver by the expansion in a short time, with a simple structure. CONSTITUTION:A bag body 10 is formed to a bag form having a nearly spheriacl shape by seaming the upper and lower base cloth 18 and 20. At the central part of the lower base clolth 20, an inflator 16 is fixed in an intruded state. In the vicinity of the inflator 16, a pair of vent holes 26 for absorbing shock through the discharge of gas after expansion, is formed. As for the vent hole 26, a seamed part 26B is formed by superposing the opposed peripheral edge parts of the hole 26A each other, and in the folded state where the hole 26A is formed to a semicircular shape, the seamed part 26B is seamed along the peripheral edge part of the hole 26A by a seaming string 28. In the initial state of the expansion of the bag body 10 in the case where the vehicle is put into a sharp deceleration state, the gas supplied from the vent hole 26 is not discharged, and the bag body 10 is expanded in a short time, even if the gas generated by the inflator 16 has the relatively low pressure and low speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air bag device bag used for an air bag device that operates when the vehicle decelerates suddenly and bulges toward the occupant when the air bag device operates.

[0002]

2. Description of the Related Art In an air bag device, for example, an air bag device mounted on a steering wheel, its base plate is fixed to a hub of the steering wheel by a fixing bolt or the like. A bag body is folded and accommodated in the pad cover of the airbag device. At the time of sudden vehicle deceleration such as a vehicle collision, the bag body expands into a flat spherical shape and is interposed between the steering wheel and the occupant to absorb the impact force of the occupant.

By the way, a vent hole is provided in a bag used in such an airbag device. This vent hole is usually formed with a constant diameter on the surface of the bag body on the side opposite to the occupant, and allows the gas inside the bag body to flow out. That is, at the time of sudden deceleration of the vehicle, the bag body swells due to the gas generated from the inflator, and the occupant comes into contact with the bag body, but at this time, the gas flows out from the vent hole, so that the internal pressure of the bag body suddenly increases. The rise is suppressed, whereby the collision energy of the occupant is smoothly absorbed, and the occupant is reliably received by the bag.

[0004]

However, the gas generated from the inflator, even when the bag is inflated,
Since it flows out from the vent hole, it is difficult to design to match the size of the vent hole with the gas pressure.

In view of the above facts, it is an object of the present invention to obtain a bag body for an airbag device, which has a simple structure and can be swollen in a short time and reliably absorb the collision energy of an occupant.

[0006]

A bag body for an air bag device according to the present invention is a bag body for an air bag device which swells by pressure gas, and a gas vent hole for discharging the pressure gas to the outside. And a sewn portion that closes the gas escape hole by closing the opposite edges of the gas escape hole to each other to close the gas escape hole and release the sewing by increasing the internal pressure.

[0007]

According to the bag body for an airbag device according to the present invention,
When the vehicle suddenly decelerates, the bag is bulged by the gas from the gas generating source such as the inflator and intervenes with the occupant. This ensures that the occupant is protected.

Since the opposite peripheral edges of the gas vent holes are sewn on each other on the bag body for an air bag device, the bag body body for an air bag device is swelled in the initial bulging state. No gas is discharged from the holes. Therefore, the airbag device bag swells in a short time even with low-pressure or low-speed gas.

When the occupant abuts on the bag body or the internal pressure increases due to the gas pressure after the bag body for the air bag device is bulged, the sewn portion of the sewn portion of the gas escape hole is broken, whereby the sewn portion is broken.
The gas vent holes are in a state of communicating the inside and outside of the airbag device bag, and the gas flows out. Therefore, the rise in the internal pressure of the airbag device bag is suppressed, the impact energy of the occupant is smoothly absorbed, and the occupant is reliably received by the airbag device bag.

[0010]

FIG. 1 shows a bag 1 according to a first embodiment of the present invention.
The schematic overall configuration of the airbag device 12 to which 0 is applied is shown in a bag body inflated state.

The airbag device 12 is arranged in the central portion of the steering wheel 14 and is rotatable or relatively rotatable with the steering wheel 14. In the airbag device 12, the bag body 10 is folded and accommodated inside. An inflator 16 for generating gas is attached inside the bag body 10. A gas generating substance is enclosed in the inflator 16, and when the vehicle is rapidly decelerated, the gas generating substance is decomposed by combustion to release a large amount of gas, and the bag body 10 can be inflated by this gas.

As shown in FIG. 2, the bag body 10 has an upper base cloth 18
The lower base cloth 20 and the lower base cloth 20 are sewn to form a substantially spherical bag shape. That is, the bag body 10 is sewn with the suture thread 22 in a state in which the outer peripheral edge portions of the upper base cloth 18 and the lower base cloth 20 which are cut into a circular shape are folded back inwardly and aligned with each other. The suture thread 22 is, for example, a 1260 denier thread.

A mounting hole 24 for mounting an inflator is formed in the central portion of the lower base cloth 20, and the inflator 16 is fixed in the mounting hole 24.
Further, in the vicinity of the mounting hole 24, a pair of vent holes 26 for releasing gas after expanding and absorbing shock is formed.

As shown in FIG. 3 (A), in the vent hole 26, the opposite peripheral edge portions of the hole 26A are overlapped with each other around the fold line L, and the overlapping portion as shown in FIG. 3 (B) is formed. 26B is provided and folded so that the hole 26A is formed in a semicircular shape. In this folded state, as shown in FIG. 3C, the overlapping portion 26B is sewn with the suture 28 along the peripheral portion of the hole 26A. The suture thread 28 is, for example, a 420-denier thread. That is, the strength of the sewn portion of the vent hole 26 is set to be equal to or lower than the strength of the outer peripheral edge portions of the upper base cloth 18 and the lower base cloth 20. For this purpose, a suture 28 having a lower tensile strength than the suture 22 is used, and the suture 22 is sewn by sewing the upper base fabric 18 and the lower base fabric 20 plural times, while the suture 28 is used. Can be applied to the strength differentiating means such as the number of times less than this, for example, the sewing is performed only once.

As shown in FIGS. 1 and 2, a strap 30 is provided inside the bag body 10 (the upper base cloth 18 and the lower base cloth 20).
32 and 34 are arranged. The straps 30 and 32 are located on both the left and right sides of the mounting hole 24, and the strap 34 is located below the mounting hole 24. The upper end portion is on the upper base cloth 18 and the lower end portion is on the lower base cloth 20, respectively. It is sewn and connected. These straps 30, 32, 34 are
When the bag body 10 is inflated, expansion and deployment of the upper base cloth 18 and the lower base cloth 20 are limited so that the bag body 10 maintains a predetermined shape.

Next, the operation of the first embodiment will be described. Figure 4
As shown in FIG. 5, in the airbag device 12 having the above-described configuration, when the vehicle is in a sudden deceleration state, gas is generated from the inflator 16 and the bag body 10 swells to intervene between the steering wheel 14 and the occupant M. To do. This allows
The occupant M is surely protected.

Since the bag body 10 is provided with the vent hole 26 in which the peripheral portion of the hole 26A is overlapped and sewn, the vent hole 26 is pierced from the vent hole 26 in the initial bulging state of the bag body 10. Gas is not exhausted. Therefore, in the bag body 10, the gas generated from the inflator 16 swells in a short time even at a relatively low pressure and low speed, and
The internal pressure of the bag body 10 reaches a value required at the initial stage of expansion.

When the occupant M abuts and the internal pressure rises after the bag body 10 bulges, the overlapping portions 26B receive a force to separate them from each other, and a pulling force acts on the suture thread 28. Since the hole 26A of the vent hole 26 is sewn with a sewing strength equal to or lower than the sewing strength of the outer peripheral edge portions of the upper base cloth 18 and the lower base cloth 20, as the inner pressure of the bag body 10 increases, The suture thread 28 breaks before the suture thread 22 on the outer peripheral edge portion of the base cloth 20. Thereby, the overlapping portion 26B of the vent hole 26
Are separated from each other and the hole 26A is in a state of communicating the inside and outside of the bag body 10, and gas flows out from the hole 26A. Therefore, the bag body 10
The excessive increase in the internal pressure is suppressed, the impact energy of the occupant M is smoothly absorbed, and the occupant M is reliably received by the bag body 10.

Here, FIG. 5 shows a bag 1 according to this embodiment.
A predicted value is shown in which the change in the internal pressure at the time of bulging of 0 is compared with the conventional bag body. The line A indicates the bag body 10 according to the first embodiment, and the line B indicates the conventional bag body.

As is clear from FIG. 5, in the bag body 10 according to this embodiment, the time T required to reach a predetermined pressure at the initial stage of expansion is the time T required by the conventional bag body.
_It is shorter than ₁ . Further, the time ET during which the internal pressure of the bag is stable is longer than the time ET ₁ of the conventional bag, and the maximum value P of the internal pressure of the bag 10 is the maximum value P ₁ of the conventional bag. Is smaller than. Where point C
Indicates the time when the occupant M contacts the bag.

Next, a second embodiment of the present invention will be described. The parts that are basically the same as those in the first embodiment have the first
The same reference numerals as in the embodiment are given and the description thereof is omitted.

FIG. 6 shows a schematic overall structure of an airbag device 42 to which the bag body 40 according to the second embodiment of the present invention is applied. Further, FIG. 7 shows a schematic side view of the bag 40 in an inflated state.

The air bag device 42 is arranged between the outer panel and the inner panel of the door 44 on the driver's side of the vehicle. For example, when a predetermined load is applied along the direction of arrow D in FIG. A sensor (not shown) is provided to detect that a predetermined load is applied to the door 44 from the outside due to the deformation of the outer panel at that time. Further, the airbag device 42 includes the inflator 16, and the bag body 40 is folded and accommodated at a position on the vehicle interior side of the inflator 16.

The bag 40 is constructed by stitching two base cloths at a predetermined position. That is, the bag body 40 is cut into a rectangular shape inside the vehicle interior (that is,
An upper base cloth 46 (on the side of the occupant M) and a lower base cloth 48 on the outside of the passenger compartment are provided, and the outer peripheral edge portions of the upper base cloth 46 and the lower base cloth 48 are folded back inward with each other to be joined together. Suture 50
Sutured by. The suture thread 50 is, for example, a 1260 denier thread.

Further, a vent hole 52 is formed in the lower base cloth 48 outside the inflator 16 (that is, in a portion of the bag body 40 opposite to the occupant). In the vent hole 52, the opposite peripheral edge portions of the hole 52A are overlapped with each other to provide the overlapping portion 52B.
Are folded to form a semicircular shape. In this folded state, the overlapping portion 52B is sewn with the suture thread 54 along the peripheral portion of the hole 52A. The suture thread 54 is, for example, a 420-denier thread. That is, the strength of the sewn portion of the vent hole 52 is set to be equal to or lower than the strength of the outer peripheral edge portions of the upper base cloth 46 and the lower base cloth 48.

Next, the operation of the second embodiment will be described. The bag body 40 having the above-described configuration is normally stored (when the airbag device 42 is inactive) in a folded state between the outer panel and the inner panel of the door 44.

From this state, when the vehicle suddenly decelerates, the sensor is turned on by deforming the outer panel, for example.
To do. As a result, the gas generating agent in the inflator 16 burns to eject a large amount of gas into the bag body 40, and the bag body 40 opens the airbag door which is also a part of the door trim (not shown) while the occupant M side. It bulges toward the part. Therefore, the side portion of the occupant M comes into contact with the bag body 40 in the expanded state, the collision energy of the occupant M is absorbed, the load on the occupant M is reduced, and the occupant M is protected.

Since the bag body 40 is provided with the vent hole 52 in which the peripheral portion of the hole 52A is overlapped and sewn, the vent hole 52 is formed from the vent hole 52 in the initial bulging state of the bag body 40. Gas is not exhausted. Therefore, the bag 40 swells in a short time even if the gas generated from the inflator 16 is at a relatively low pressure and low speed, and
The internal pressure of the bag body 40 reaches a value required at the initial stage of expansion.

When the occupant M abuts and the internal pressure rises after the bag body 40 swells, the hole 52A of the vent hole 52 is inserted into the upper base cloth 4
6 and the outer peripheral edge portion of the lower base cloth 48 are sewn with a sewing strength equal to or lower than the sewing strength, so that as the inner pressure of the bag body 40 increases, a pressing force acts on the vent hole 52 and the upper base cloth 46 and the lower base cloth. The suture thread 5 precedes the suture thread 50 on the outer peripheral edge of the cloth 48.
4 breaks. As a result, the overlapping portion 52B of the vent hole 52 is separated from each other and the hole 52A communicates with the inside and outside of the bag body 40, and gas flows out from the hole 52A. Therefore, an excessive increase in the internal pressure of the bag body 40 is suppressed, the impact energy of the occupant M is smoothly absorbed, and the occupant M is reliably received by the bag body 40.

The type of the airbag sensor in the present embodiment is not limited to the mechanical type or the electrical type, the gas supply source is not limited to the structure shown in the figure, and pressure gas is emitted from other vehicle body parts. It may be a guide. Further, in the present embodiment, the inflator 16 is attached to the mounting opening 2 of the lower base cloths 20 and 48.
However, the inflator 16 can be installed in other parts of the vehicle body.

Further, the strength of the sutures 28 and 54 is not limited to that of this embodiment, but the opposite peripheral edge portions of the holes 26A and 52A are sewn together to close the holes 26A and 52A, and the bag body 10, The strength can be changed as appropriate as long as the strength is such that it can be broken by the increase in the internal pressure of 40 to release the sewing. Further, in the above-described embodiment, the suture 28 is sewn in a semicircular shape as shown in FIG. 3C, but it may be sewn in a bent linear shape so that tensile stress can be partially concentrated. . Further, the suture thread 28 may be sewn around the hole 26A over the entire circumference thereof, and may be sewn only on the other part while leaving a part of the circumference. Alternatively, in the above-mentioned embodiment, various threads such as natural fiber or synthetic fiber can be applied to the sewing thread used for sewing, and glass, metal, etc. other than thread may be used as long as they can be sewn.

[0032]

As described above, the bag body for an airbag device according to the present invention has an excellent effect that it can be swollen in a short time and can reliably absorb the collision energy of the occupant with a simple structure.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a configuration of a bag body of an airbag device according to a first embodiment of the present invention in an inflated state.

FIG. 2 is a bottom view showing the bag body according to the first embodiment of the present invention as viewed from the vehicle body side.

FIG. 3A to FIG. 3C are perspective views showing a procedure for sewing the vent hole of the bag body according to the first embodiment of the present invention.

FIG. 4 is a schematic side view in a state where the airbag device to which the bag body according to the first embodiment of the present invention is applied operates and the bag body is inflated.

FIG. 5 is a diagram comparing a change in internal pressure when the bag body according to the first embodiment of the present invention is inflated with a conventional bag body.

FIG. 6 is a schematic overall configuration diagram of an airbag device to which a bag body according to a second embodiment of the invention is applied.

FIG. 7 is a perspective view of a bag body according to a second embodiment of the present invention, partially cut away and viewed from the side opposite to the occupant.

[Explanation of symbols]

 10 Bag (Bag for Air Bag Device) 12 Air Bag Device 26A Hole (Hole for Gas Release) 26B Overlapped Part (Sewn Part) 40 Bag Body (Bag Body for Air Bag Device) 42 Air Bag Device 52A Hole (Gas 52B Overlapped part (sewn part)

Claims (1)

[Claims] 1. A bag body for an airbag device that swells by pressure gas, wherein a gas vent hole for exhausting the pressure gas to the outside and an opposite peripheral edge portion of the gas vent hole are sewn together. A bag body for an airbag device, comprising: a sewn portion that closes the gas vent hole and breaks when the internal pressure rises to release sewing.