JP4444850B2 - Airbag device - Google Patents

Description

  The present invention relates to an airbag device that forms a vent hole in a base fabric that constitutes an airbag and opens the vent hole in a process in which the airbag is deployed with gas generated by an inflator at the time of a vehicle collision.

  The airbag device is deployed in the passenger compartment by gas supplied from the inflator at the time of a vehicle collision, and restrains the occupant. In this airbag, the process of deploying the airbag to optimally set its internal pressure A vent hole is provided to release the gas. However, if the vent hole is completely opened from the initial stage of deployment of the airbag, the gas supplied from the inflator leaks from the vent hole and the rise of the internal pressure of the airbag is delayed, so that the airbag is deployed. Various airbag devices that open vent holes along the way have been proposed.

For example, the first vent hole is formed on the inner side of the first sewing portion that joins the periphery of the front and back base fabrics constituting the airbag, and from the first vent hole until the first sewing portion is broken. When the gas is discharged and then the gas supply speed is increased and the first sewing portion is broken, the second sewing portion formed outside the first sewing portion and the first sewing portion are separated. There is one in which gas is discharged from the second vent hole.
Japanese Patent Laid-Open No. 11-20588

  However, in the above-described conventional airbag device, gas is discharged from the second vent hole located outside the first sewing portion only after the first sewing portion is broken. There is a problem that the position of the vent hole is naturally restricted, for example, it must be set outside the sewing portion, and the degree of freedom in setting the discharge position of the gas discharged from the vent hole is reduced.

  Therefore, an object of the present invention is to provide an airbag device that can optimally set the position of a vent hole from which gas is discharged to the outside due to the breaking of the sewing portion.

In order to achieve the above object, the invention described in claim 1 is a first base fabric (for example, the first base fabric 36 in the embodiment) constituting the surface of an airbag (for example, the airbag 32 in the embodiment). ) And a second base fabric constituting the back surface of the airbag (for example, the second base fabric 37 in the embodiment), and the first base fabric and the second base fabric are overlapped and joined. The air bag is formed by attaching an inflator (for example, the inflator 31 in the embodiment) that generates gas to the second base fabric, and a vent hole (for example, the vent hole 37b in the embodiment) for discharging gas is attached. In the provided airbag apparatus, a third base cloth (for example, a peripheral edge of which is joined together with the first base cloth and the second base cloth between the first base cloth and the second base cloth (for example, A third base cloth 41) in the embodiment is provided, the inflator is attached to the third base cloth, and a vent hole for discharging gas (for example, the vent hole 41b in the embodiment) is provided as a vent hole in the second base cloth. A joint portion (for example, sewing in the embodiment) that is provided on the outer side and joins the first base fabric and the third base fabric to the inner side of the vent hole of the third base fabric and breaks by a predetermined pressure. Part 39... Is provided.
By comprising in this way, the vent hole of a 3rd base fabric is opened after the junction part of a 1st base fabric and a 3rd base fabric fractures | ruptures, and the gas discharged | emitted from this vent hole is 2nd It is discharged to the outside through a vent hole formed in the base fabric.

  According to the invention described in claim 1, the vent hole of the third base fabric is opened after the joint portion between the first base fabric and the third base fabric is broken, and the gas discharged from the vent hole is Since it is discharged to the outside from the vent hole formed in the second base fabric, the joint portion between the first base fabric and the third base fabric is broken and the third base fabric is sufficiently expanded, The internal pressure can be adjusted by exhausting the gas from the vent hole of the base fabric, and the gas exhausted from the vent hole of the third base fabric is as set from the vent hole set at the optimum position of the second base fabric. It is discharged outside in the direction. Therefore, it is possible to increase the degree of freedom in setting the discharge direction of the discharged gas while ensuring the optimal internal pressure of the airbag.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an airbag module 13 is housed inside a steering wheel 12 disposed in front of the seat 11 of the driver's seat.

As shown in FIG. 2, the steering wheel 12 has a boss portion 16 fixed to the rear end of the steering shaft 14 by a nut 15, and a cup-shaped front cover 17 is fixed to the boss portion 16. A rear cover 19 is fixed to the periphery of the front cover 17 by bolts 18 so as to close the front cover 17. A plurality of radially extending spoke portions 20 are attached to the outer peripheral surface of the front cover 17, and a steering wheel body 21 is supported by the spoke portions 20.
Here, a retainer 22 is fastened together with the bolts 18 on the inner peripheral surface of the rear cover 19, and the airbag module 13 is supported on the retainer 22. A tear line 19 a that is broken when the airbag 32 is inflated is formed on the inner surface of the rear cover 19.

  The airbag module 13 includes an inflator 31 filled with a propellant that generates high-pressure gas by combustion, an airbag 32 configured by sewing a base fabric, and a fixing ring 33 that fixes a base portion of the airbag 32. Yes. The flange 31a of the inflator 31 and the fixing ring 33 are superposed on the front surface and the rear surface of the retainer 22, and are fastened and fixed by bolts 34 and nuts 35. The base portion of the airbag 32 is fixed between the rear surface of the retainer 22 and the front surface of the fixing ring 33.

  As shown in FIGS. 3 to 5, the circular airbag 32 has a first base fabric (first base fabric) 36 constituting a surface thereof (a side facing the occupant) and a second base constituting a rear surface thereof. Cloth (second base cloth) 37, the outer peripheral edge of the first base cloth 36 and the inner peripheral edge of the second base cloth 37 are overlapped, and the outermost side of the first base cloth 36 is integrated with the sewing portion 38. It is sewn. That is, the first base fabric 36 is a circular member having a sewing portion 38 set on the outer peripheral edge, but the second base fabric 37 is a bag-shaped member formed so that the peripheral edge wraps inwardly. The sewing portion 38 of the second base fabric 37 is set to the opening periphery 37d.

  The second base cloth 37 has a circular opening 37a surrounding the inflator 31 at the center, through holes 37c of bolts 34 formed around the opening 37a, and the inflation of the airbag 32 in the vicinity of the opening 37a. Sometimes two circular vent holes 37b are formed through which some of the internal gas escapes. Here, the vent holes 37b are formed on both sides of the opening 37a.

  As described above, the second base fabric 37 is sandwiched between the rear surface of the retainer 22 and the front surface of the fixing ring 33 together with a third base fabric (third base fabric) 41 to be described later. Since it is tightened, the gas generated by the inflator 31 is supplied into the airbag 32 from the central opening 37 a of the second base fabric 37.

  A third base cloth 41 is interposed between the first base cloth 36 and the second base cloth 37. The third base cloth 41 is formed in a circular shape with the same outer dimensions as the second base cloth 37. Similarly to the second base cloth 37, the third base cloth 41 also has a circular opening 41 a surrounding the inflator 31, through holes 41 c of bolts 34 formed around the opening 41 a, and the airbag 32. Two circular vent holes 41b are formed to allow some of the gas inside to escape during expansion. Here, the vent holes 41b are on both sides of the opening 41a, and are completely opened when the sewing portions 39 are completely broken at positions outside the spiral sewing portions (joining portions) 39 described later. It has come to be. The shape of the vent hole 41b is not limited to a circular shape, and may be an arc shape as shown in FIGS. 3 and 4 as long as it is a cross-sectional shape necessary for securing a gas discharge amount.

The third base cloth 41 is overlapped with the outer peripheral edge of the first base cloth 36 and the opening peripheral edge 37d of the second base cloth 37, and as described above, the first base cloth 41 is formed at the outermost sewing portion 38. The cloth 36 is joined to the second base cloth 37 and is sewn to the first base cloth 36 by a spiral sewing portion 39 at an inner position of the sewing portion 38. The spiral sewing portion 39 is composed of three sewings, but the number of sewing can be freely set.
Here, the outer peripheral sewing portion 38 is firmly sewn with a thick thread so as not to be broken when the airbag 32 is inflated. The inner spiral portions 39... It is sewn fragilely with fine thread so that it can be gradually broken from the inner end.
Therefore, the vent hole 41b of the third base cloth 41 is provided outside the vent hole 37b of the second base cloth 37, and a spiral sewing portion 39 is formed inside the vent hole 41b. .

According to the above embodiment, when a gravitational acceleration of a predetermined value or more is detected at the time of a vehicle collision, the inflator 31 is ignited, and the folded airbag 32 starts to inflate with the gas generated by the inflator 31. When the airbag 32 is inflated, the rear cover 19 is broken at the tear line 19a under the pressure, and the airbag 32 is deployed into the vehicle compartment from the opening formed there.
As shown in FIG. 6, when the airbag 32 is inflated, the spiral sewing portions 39... Integrally join the first base cloth 36 and the third base cloth 41, so that the airbag 32 is inflated at a stretch. It is possible to restrain the passenger softly. As the internal pressure of the airbag 32 increases, the spirally-shaped sewing portion 39. Finally, it can be developed into a flat shape in the front-rear direction to exhibit the maximum restraining force.

  The first base cloth 36 and the third base cloth 41 are restrained by the spiral sewing parts 39... Until the spiral sewing parts 39. The hole 41b is closed by the first base cloth 36 to prevent gas leakage, and the internal pressure of the airbag 32 can be quickly raised and the internal pressure can be appropriately maintained. Here, since there is resistance when the gas generated by the inflator 31 passes between adjacent sewing parts 39, each sewing part 39 is broken from its inner terminal and gradually developed. The gas is slightly discharged from the vent hole 37b through the vent hole 41b, but the airbag 32 is surely deployed.

  Then, as shown in FIG. 7, when the spiral sewing parts 39 are gradually broken from the inside, and when the sewing parts 39 are completely broken at the end of deployment of the airbag 32 as shown in FIG. 41 vent hole 41b is completely opened. As a result, excess gas in the airbag 32 is discharged from the vent hole 41b, and an excessive increase in the internal pressure of the airbag 32 can be prevented. At this time, the gas discharged from the vent hole 41b is released between the second base cloth 37 and the third base cloth 41, and is released to the outside from the vent hole 37b formed in the second base cloth 37. Therefore, the gas released from the airbag 32 to the outside (in the vehicle compartment) is released to the front side from the vent hole 37b formed at the optimum position of the second base fabric 37.

  That is, in order to ensure a large capacity of the airbag 32 so that the vent hole 41b is not opened until the sewing portions 39 of the first base cloth 36 and the third base cloth 41 are completely broken, the vent hole 41b is secured. However, as a result, it is the vent hole 37b of the second base fabric 37 that discharges the gas in the airbag 32 to the outside. Since the deployment performance of the airbag 32 is not adversely affected no matter where the holes 37b are arranged, the vent holes 37b through which gas is discharged can be set at the optimum position, and the degree of freedom in arrangement can be increased.

  Accordingly, the degree of freedom in setting the discharge direction of the discharged gas (the discharge direction of the gas discharged from the vent hole 37b of the second base fabric 37) is increased while ensuring the internal pressure of the airbag 32 in an optimal state. Can do. Here, since the second base cloth 37 is a bag-like member formed so that the periphery of the second base cloth 37 wraps inwardly, the gas released from the vent hole 41b of the third base cloth 41 is contained in the second base cloth 37. It flows smoothly along the peripheral surface and is smoothly discharged from the vent hole 37b of the second base fabric 37.

  FIG. 9 shows a second embodiment of the present invention. In the embodiment described above, the first base cloth 36 and the third base cloth 41 are sewn by the spiral sewing portions 39..., But in this embodiment, three concentric circles (two or four or more) may be used. Are sewn at a sewing portion 39A. In addition, since another structure and effect | action are the same as that of the said embodiment, the same code | symbol is attached | subjected to the same part and description is abbreviate | omitted. In this embodiment, when the airbag 32 starts to be deployed, the sewing portion 39A... Is broken in order from the inner sewing portion 39A to the outer sewing portion 39A, and the airbag 32 is deployed in stages. Therefore, the vent hole 41b is not opened unless all the sewing parts 39A are completely broken, and therefore there is no gas leakage from the vent hole 41b during deployment, which is advantageous in that the inflator 31 can be reduced in size. .

  In addition, this invention is not restricted to the said embodiment, For example, it can apply to the airbag apparatus of a driver's seat. Further, the shape of the airbag 32 is not limited to a circular shape, and various modes such as a wide elliptical shape can be adopted. Further, the second base fabric 37 may be formed in a circular shape in which a sewing portion 38 is set on the outer peripheral edge portion in the same manner as the first base fabric 36. Furthermore, the shape of the vent hole 37b of the second base fabric 37 is not limited to a circular shape. Further, a breathable cloth may be used for the second base cloth 37.

1 is a perspective view of a first embodiment of the present invention. It is sectional drawing which follows the AA line of FIG. It is a disassembled perspective view of an airbag. It is a rear view of an airbag. It is sectional drawing which follows the BB line of FIG. It is action explanatory drawing at the time of airbag deployment. It is action explanatory drawing at the time of airbag deployment. It is action explanatory drawing at the time of airbag deployment. It is a rear view of the airbag equivalent to FIG. 4 of 2nd Embodiment.

Explanation of symbols

31 Inflator 32 Airbag 36 First Base Fabric (First Base Fabric)
37 Second base fabric (second base fabric)
37b Vent hole 39 Sewing part (joint part)
41 Third base fabric (third base fabric)
41b Bent hole

Claims (1)

  By forming the first base fabric constituting the surface of the airbag and the second base fabric constituting the back surface of the airbag, and overlapping and joining the first base fabric and the second base fabric. In the airbag apparatus in which the airbag is formed, an inflator for generating gas is attached to the second base cloth, and a vent hole for discharging gas is provided, the first base cloth and the second base cloth A third base fabric whose periphery is joined together with the first base fabric and the second base fabric, a vent hole for attaching the inflator to the third base fabric and discharging gas Is provided outside the vent hole of the second base fabric, the first base fabric and the third base fabric are joined inside the vent hole of the third base fabric, and are broken by a predetermined pressure. Airbag device characterized by providing a joint .

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