WO1999014077A2

WO1999014077A2 - An airbag system

Info

Publication number: WO1999014077A2
Application number: PCT/KR1998/000280
Authority: WO
Inventors: Dae Sung No
Original assignee: Dae Sung No
Priority date: 1997-09-13
Filing date: 1998-09-12
Publication date: 1999-03-25
Also published as: WO1999014077A3; AU9188898A; KR19990025594A; KR100241145B1

Abstract

An airbag system built in the steering wheel (11) is provided to all kinds of automotive vehicles, said airbag system includes a compartment (10) and an inflation device (30), the compartment including: a lower case (13) coupled with a steering frame (12) attached to the center of a steering wheel (11); a steering boss (14) that passes through the center of the steering frame (12) and couples with it; a reception box (15) for allowing the inflation device (30) to be inside the steering frame (12); an airbag case (16) holding an airbag (A) connected to the inflation device (30), which is mounted on the reception box (15); and an assembly plate (17) for integrating the outside of the airbag case (16) with the reception box (15), and the inflation device (30) including: a movable portion (40) which includes one fixed end, and the other free end turning on the fixed end when the impact over a specific speed is applied to the front of a vehicle; a support portion (50) for releasing a trigger portion (70) that is supported by it when the free end of the movable portion (40) descends; a firing spring loaded trigger portion that turns to strike a piercing pin (80) when the support force is released by the support portion (50); and a discharge manifold (90) which is operated by the trigger portion, to guide the discharge, to the airbag (A), of the gas jet ejected from the gas cylinder (96).

Description

AN AIRBAG SYSTEM

Technical Field

The present invention relates generally to vehicular airbag systems, specifically, to an airbag system that is mounted in a steering wheel.

Background Art

In general, airbag systems that are installed at a central portion of the steering wheel of a vehicle have constructions that allow the airbag to be deployed between the steering wheel and driver to protect the driver if the vehicle collides. This conventional airbag system includes an impact sensor that is installed at the front of the vehicle, and an inflation device, which includes the necessary propellants to inflate the airbag, at the center of the steering wheel.

When the impact sensor that is installed at the front of the vehicle senses a frontal collision, it produces a signal that is transmitted to the inflation device, which produces the gas that inflates and deploys the airbag between the steering wheel and the driver.

Conventional airbag systems have the disadvantage of a complicated construction and the consequential high production cost because the impact sensor, for sensing a frontal collision, is installed at the front of the vehicle separate from the inflation device that operates the airbag. In addition, if there is a short in the wires connecting the impact sensor or another malfunction due to moisture therein, the airbag deploys in the absence of a collision, causing a dangerous situation. Beyond the issue of airbag malfunctions is the cost of replacing these airbags that once inflated cannot be reused.

Summary of the Invention Accordingly, the present invention to directed to an airbag system that substantially obviates one or more of the problems, limitations or disadvantages of the conventional art.

It is an object of the present invention to provide an airbag system which operates without a separate power source, and can be easily installed, even in vehicles not originally designed for airbag installation, has a reusable inflation device, and can quickly deploy an airbag using a gas discharge that is triggered by physical inertia when an impact exceeding a specific magnitude occurs to the front of vehicle during operation.

To achieve the above objectives, the invented airbag system includes a compartment and an inflation device, the compartment having: a lower case located under a steering frame connected to the center of the steering wheel so that an installation space is created at the center of the steering wheel; a steering boss that passes through the center of the lower case and is positioned under the center of the steering frame, and includes a steering wheel shaft connection ring and an integral horn contact ring; a reception box mounted to the steering frame holding the inflation device and the airbag in order: an airbag case that holds the airbag over the reception box. including a lid and horn buttons on both sides; and an assembly plate positioned over the reception box, to allow the lid to be taken off the airbag by a discharge pressure of the airbag, and fixing the airbag case on the reception box, and the inflation device put into a compartment having: a movable portion that includes one fixed end, and the other free end turning on the fixed end when a collision happens to the front of a vehicle; a support portion that releases a trigger portion when the free end of the movable portion descends; a trigger portion for elastically turning to strike a piercing pin when the trigger portion is released by the support portion; a piercing pin that is operated by the trigger portion, to perforate the seal over the mouth of a gas cylinder; and a discharge manifold to smoothly discharge the gas, ejected by the gas cylinder when perforated by the piercing pin, to the airbag.

Additional advantages, objects and other features of the invention are set forth, in part in the description which follow, and in part will be apparent to those with ordinary skill in the art upon examination of the following or may be learned by practice and application of the invention. The objects and advantages of the invention may be realized and attained, as pointed out in the appended claims.

Brief Description of Drawings

The present invention can be clearly understood from the detailed description given below and the accompanying drawings, which are given for illustration purposes only, and thus do not limit beyond the stated claims, wherein:

FIG. 1 is a side view of the state in which an airbag system according to the present invention operates; FIG. 2 is an exploded, perspective view illustrating the configuration of the present invention;

FIG. 3 is a sectional side view showing how the compartment and the inflation device of the present invention are coupled;

FIG. 4 is an exploded, perspective view of the inflation device of the present invention: FIG. 4A is an exploded, perspective view of a movable portion and a support portion;

FIG. 4B is an exploded, perspective view of a trigger portion;

FIG. 4C is a perspective view showing the exterior of a piercing pin mechanism and a discharge manifold;

FIG. 5 is a plan view of the inflation device of the airbag system according to the present invention;

FIG. 6 is a cross-section taken along line A-A of FIG. 5; and

FIG. 7 is a cross-section taken along line B-B of FIG. 5.

Best Mode for carrying Out the Invention The preferred embodiment of the present invention is apparent from the following detailed description and clarified by the accompanying drawings.

FIG. 2 is an exploded, perspective view of a compartment of the present invention, FIG. 3 is a side section showing a state in which the compartment and a inflation device of the present invention are coupled, and FIG. 4 is an exploded, perspective view of the inflation device of the present invention.

The present invention comprises a compartment 10 including: a lower case 13 coupled with a steering frame 12 at the center of a steering wheel 1 1 ; a steering boss 14 that passes through the center of the steering frame 12, to be coupled; a reception box 15 for allowing an inflation device 30 to be inside the steering frame 12; an airbag case 16, holding an airbag A. which is connected to the inflation device 30, which is mounted on the reception box 15; and an assembly plate 17 that integrally fixes the outer sides of the airbag case 16 to the reception box 15.

The present invention also comprises an inflation device 30 including: a movable portion 40 which includes one fixed end, and the other free end turning on the fixed end when the impact over a specific speed is applied to the front of a vehicle; a support portion 50 for releasing a trigger portion 70 that is supported by it when the free end of the movable portion 40 descends: a trigger portion 70 for elastically turning to strike a piercing pin 80 when a support force is released by the support portion 50; a piercing pin 80 that is operated by the trigger portion 70, to perforate the seal over the mouth of a compressed gas cylinder 96; and a discharge manifold 90 that guides the discharge of gas from cylinder 96 to the airbag A when perforated by the piercing pin 80.

According to a first embodiment of the compartment 10, the steering frame 12 is bent downward to form an installation space at the center of the steering wheel 11 , and includes a coupling plate 121 having a boss installation aperture 122 at its center and multiple coupling apertures 123 around the boss installation aperture 122. The lower case 13 has an open top so as to cover the installation space formed under the steering frame 12, and four corners which are bolted to the four corners of the steering frame 12. The steering boss 14 includes: a connection ring 141 passing through the center of the lower case 13 before being in plane-contact with the coupling plate 121 at the center of the steering frame 12, and then bolted to the boss installation aperture 122; and an integrated horn contact ring 142 and a indicator signal contact ring 143 downward positioned a selected spaced apart distance from connection ring 141. The reception box 15 that allows the inflation device 30 to be held within the steering frame 12, includes fixation flanges 151 extending outward from its both sides, where coupling apertures 152 are formed on every corner. The airbag case 16 comprises: an open top; a pair of holes 161 at the bottom of a housing 160; installation flanges 162 which extend out from the both side of the housing 160; form horn buttons 163 on their respective rear ends; and projections 164 which are formed at the rear side of the housing 160 equidistant and longitudinally. A lid 165 is fitted onto the projections 164, to cover the airbag case 16. The assembly plate 17 mates to the fixation flanges 151 of reception box 15 and the installation flanges 162 of airbag case 16. and includes the edge 171 for holding the outer sides of the lid 165. A rectangular lid-guiding hole 172 is formed inside the edge 171 so that the lid 165. whose outer sides are pressed in, is lifted from the airbag case 16 by the discharge of the airbag A. In accordance with a first embodiment of the inflation device 30, the movable portion 40 is flexibly coupled to the support portion 50 by means of a hinge 41. and elongated in the direction of the opposite side. The movable portion 40 forms a movable lever 42 having a fitting hole 421 in the center of one side. A movable plumb 43 of a specific weight is provided under the other side of movable lever 42. As illustrated in FIGs. 4A and 6, the support portion 50 comprises a sub base 51. to bolt onto main base 20 having: a shaft reception stand 511 protruding out so as to couple with one end of the movable lever 42 by the hinge 41; a guide aperture 512 on one side; and a mounting groove 513 on the other side; and a bearing guide plate 514 with vertical inner face that is formed under the shaft reception stand 511. A spring 521 is mounted into the mounting groove 513 of the sub base 51. A guiding pin 52 passes through the fitting hole 421 of movable lever 42, to fit on the spring 521 in such a way that the lower end of the guiding pin 52 is coupled with the center of mounting groove 513 of the sub base 51.

A pair of support bearings 531 are formed to roll along the vertical inner face of the bearing guide plate 514 of the sub base 51, and a locking bearing 532 is provided at an opposite end. The support bearings 531 and the locking bearing 532 mate with each other by a fixing holder 53. The fixing holder 53 is divided into two parts, to form a rectangular fixing hole 533 on its center.

An ascent/descent rod 54 is provided to pass through the guide aperture 512 of the sub base 51. The ascent/descent rod 54 includes: a rounded top; a groove 541 on its upper region; a fitting flange 542 extending outward, spaced apart downward a distance from the groove 541 ; and a fitting groove 543 located under the fitting flange 542, to be assembled to the fixing hole 533 of the fixing holder 53 for sliding along the fixing hole 533 horizontally.

The ascent/descent rod 54 passes up through the guide aperture 512 of the sub base 51 until the fitting flange 542 fits under the guide aperture 512. The upper part of rod 54. which passes through the guide aperture 512, fits closely to a spring 544, and a washer 545 is placed over the spring 544. Following this, a spring washer 546 is inserted into the groove 541 of the ascent/descent rod 54, so that the spring 544 is fixed and prevented from moving upward. The lower part of rod 54. which is assembled to the fixing hole 533 of fixing holder 53. is inserted into a fixation aperture 22 formed vertically through the main base 20.

As depicted in FIGs. 4A. 4C, 5, 6, and 7, the trigger portion 70 comprises a piercing trigger 74 having: a spring fixing protrusion 742 at one side of its front; a bearing fitting recess 744 formed at the opposite corner; a striking end 743 bent from one side of its rear end to a specific position of the other side; and a shaft aperture 741 provided at the center of the striking end 743. A first firing spring 71 and a second firing spring 72 are divided into two parts, vertically spaced a distance that allows the piercing trigger 74 to be located between the two firing springs 71 and 72. The first and second firing springs 71 and 72 include upper fitting projections 71 1 and 721 protruding up. and lower fitting projections 712 and 722 protruding down respectively, and integral fitting parts 713 and 723 extending horizontally from a portion that vertically spaces the two firing springs 71 and 72.

In addition, the trigger portion 70 comprises a support cover 75 for covering the first and second firing springs 71 and 72, and a central shaft 73 on which the piercing trigger 74 turns along with the first and second firing springs 71 and 72, at the main base 20. The support cover 75 is plate-shaped to cover the upper portion of the first and second firing springs 71 and 72 and fix the central shaft 73, and includes a boss 751 where a fixing hole 752 passes through the center of its bottom. The upper portion of the central shaft 73 has a diameter that allows the shaft aperture 741 of the piercing trigger 74 to be rotatively positioned. The upper step of central shaft 73 is different from the lower step in length. Coupling apertures 731 and 732 of a specific depth are formed in upper and lower portions of the shaft, respectively. In assembling the trigger portion 70 constructed above, the lower fitting projections 712 and 722 of the first and second firing springs 71 and 72 are inserted vertically into an aperture 212 of main base 20, before being fitted on the fixing protrusion 742 formed at the other side of the piercing trigger 74. After that, the central shaft 73 passes through the shaft aperture 741 of piercing trigger 74, and the lower portion of central shaft 73 is inserted into a shaft reception aperture 21 1 of a main base boss 21. before coupled with bottom of the main base 20 under the boss 21 by means of a bolt 24.

After assembly is completed as described above, the upper portion of central shaft 73 is inserted into the fixing hole 752 formed in the boss 751 of support cover 75. Simultaneously with this, the upper fitting projections 71 1 and 721 of first and second firing springs 71 and 72 are inserted through an aperture 753 formed in the support cover 75.

As shown in FIGs. 4B and 7, the piercing pin 80 includes a striking end 811 having a rounded end, and a fitting flange 812 formed in the outer circumference at a position some distance from striking end 81 1 , where a spring 82 presses against it. At the opposite end of the piercing pin 80 is an inlet pipe 813 with a sloping end which has an opening 814; and vent holes 815 radially on the inlet pipe 813 outer surface.

As shown in FIGs. 4C -and 7, the discharge manifold 90 includes two connectors 91 for connecting two gas cylinders 96 parallel with each other, and two couplers 92, the connector 91 each having: a gas cylinder connection 91 1 that threads onto the gas cylinder 96; a piercing pin guide aperture 912 formed horizontally therein, for guiding the piercing pin 80 as it slides horizontally; and a gas aperture 913 formed vertically under the piercing pin guide aperture 912, for guiding the gas ejected from the gas cylinder 96 upward, and the coupler 92 each having a hole 921 on its top that threads onto the four corners of the connector 91 through the installation aperture 932 of a lower cover 93.

Over the coupler 92, there are provided the lower cover 93 for diffusing the gas ejected, a gas ejector 94 for ejecting the gas by connecting the lower cover 93 with the connector 91. and a upper cover 95 allowing the gas diffused in the lower cover 93 to be discharged to the airbag A. and covering top of the lower cover 93. The following, detailed description relates to this. The lower cover 93 forms a pair of rectangular, recessed diffusion chambers 931. the diffusion chamber each having an installation aperture 932 at one side.

The gas ejector 94 includes: an ejection aperture 941 formed at its center, that connects the installation aperture 932 of lower cover 93 and the hole 921 of coupler 92 before inserted into the gas guide aperture 913 of the connector 91 ; and a coupling flange 942 that connects to the ejection aperture 941. The gas ejector 94 passes through the installation aperture 932 of lower cover 93, before being mounted to and coupled with the lower cover 93 using screws.

The upper cover 95, which covers the same area as the lower cover 93 's top, has two gas discharging holes 951 formed at locations corresponding to respective centers of the diffusion chambers 931 , two guide plates 952 inside the respective gas discharge nozzles 951. which guide a discharged gas jet in the different direction so as to prevent gas collision, and an airbag attachment line 953 around the gas discharge nozzle 951, for attaching the airbag A. As illustrated in FIG. 7. the upper cover 95 covering the top of lower cover 93 is mounted to the airbag case 16. The operation of the airbag system of the present invention is described as follows.

As depicted in FIGs. 5 and 6, in the inflation device 30, the fixing holder 53 is pressed vertically to move downward while the piercing trigger 74 is turned inward to apply an elastic force to the first and second firing springs 71 and 72. When releasing a force from the fixing holder 53 that moves downward, the fixing holder 53 is returned up to its original position, and the locking bearing 532 provided at the front end of fixing holder 53 fits closely onto and is fixed at the fitting recess 744 of piercing trigger 74.

An elastic force caused by the piercing trigger 74 coupled with the first and second firing springs 71 and 72 enables the fixing holder 53, consisting of the support bearing 531 and locking bearing 532, to move in the opposite direction and not interfere with the ascent/descent rod 54. That is, the fitting groove 543 of ascent/descent rod 54 slides along the fixing hole 533 of fixing holder 53 in the opposite longitudinal direction, so that the force applied by the piercing trigger 74 doesn't interfere with the ascent/descent rod 54, and pushes the fixing holder 53 only. In this respect, a pair of support bearings 531 of fixing holder 53 are in plane-contact with the inner face of bearing guide plate 514, formed on the sub base 51, in such a way that they facilitate the ascent/descent operation of the ascent/descent rod 54.

In case an impact force exceeding than a specific value indicating a frontal collision at about 40km/h involves the moving vehicle while the piercing trigger 74 fits on and is held by the locking bearing 532 of support portion 50, the movable plumb 43 of movable portion 40 turns in the collision direction, and the ascent/descent rod 54 being placed closely to the movable lever 42 is. accordingly, pressed downward, as shown in FIG. 6.

As the fixing holder 53 coupled with the ascent/descent rod 54 descends, the support bearings 531 slide down vertically along the inner face of the bearing guide plate 514 of the sub base 51. Therefore, the locking bearing 532 of fixing holder 53 descends under the piercing trigger

74. the locking bearing 532 become detached from the fitting recess 744 of the piercing trigger 74. When a locking state is released from the piercing trigger 74 by the vertical descent of locking bearing 532. the elastic force of the first and second firing springs 71 and 72 coupled with the piercing trigger 74 is restored, and the piercing trigger 74 turns on the central shaft 73 in a direction, to quickly hammer the end 81 1 of the piercing pin 80 with its striking end 743. as shown in FIG. 5.

As illustrated in FIG. 7, the sloping end 813 of the piercing pin 80 perforates and is inserted through the seal over the mouth of gas cylinder 96, and the gas filled in the gas cylinder 96 is discharged to the vent holes 815 through the opening 814 of the piercing pin 80. After that, the piercing pin 80 returns to its original position by the restoring force of the spring 82. coupled with the piercing pin 80. and the pressure of the discharged gas, completely uncovering the mouth of gas cylinder 96. The gas passes through the gas guide aperture 913 of the connector 91, before discharging into the diffusion chambers 931 of lower cover 93 through the ejection aperture 941 of gas ejector 94. After that, the gas ejected into the diffusion chambers 931 is diffused in the longitudinal direction, and also discharged through the gas discharge nozzle 951 of the upper cover 95 along the guide plates 952 which protrude and slope in the opposite direction so that the gas discharged from the respective guide plates 952 allows the airbag A to inflate quickly, not colliding with each other. The inflating airbag A forces the lid 165 covering the airbag case 16 to lift, before developing between the steering wheel 11 and driver, minimizing injury to the driver, as shown in FIG. 1.

To reuse the airbag system of the present invention, after being deployed in the collision of vehicle, the inflation device 30 is detached from the compartment 10, to restore the support portion 50 and the trigger portion 70 to their original states. After that, the gas cylinder 96 is replaced with a new charged one, before the inflation device 30 is reassembled in the compartment 10 as originally assembled. As described above, the inflation device and the compartment having the airbag are simplified into a single set, the inflation device is reusable, and the airbag system operates without separate power source, by quickly supplying the airbag with the gas discharged by physical inertia when the impact over a specific speed is applied to the front of vehicle during operation. Therefore, the system is easily installed, even in vehicle not originally equipped with it. The system can be reused to reduce repair costs while still protecting the driver from frontal collisions of the vehicle. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as recited in the accompanying claims.

Claims

WHAT IS CLAIMED IS:

1. An airbag system comprising a compartment and an inflation device, the compartment including: a steering frame bent downward to form an installation space at the center of the steering wheel and having a coupling plate forming a boss installation aperture and coupling apertures around the boss installation aperture; a lower case having an open top so as to cover the lower part of the installation space formed on the steering frame, and four corners which are bolted to the four corners of the steering frame; a steering boss having a connection ring passing through the center of the lower case before being in plane-contact with the coupling plate at the center of the steering frame, and bolted to the boss installation aperture; a reception box with predetermined space inside positioned over the steering boss and having a fixation flanges extending outward from its both sides, where coupling apertures formed on every corner; an airbag case with an open top bolted to the reception box, said airbag case including: holes at the bottom of housing; an installation flange extending out from both sides of the housing; and a lid secured to the one side of the housing for rotating; and an assembly plate mating to the fixation flanges of reception box and the installation flanges of the airbag case, said assembly plate including: an edge for holding the outer sides of the lid; a rectangular lid-guiding hole formed inside the edge 171 so that the. lid, whose outer sides are pressed in, is lifted from the airbag case by the discharge of the airbag; and the inflation device including: a movable portion having a fixed end, and the other free end turning on the fixed end when the impact over a specific speed is applied to the front of a vehicle; a support portion supporting the movable portion that is hinged on one side of the support portion, and releasing a trigger portion engaged when the free end of the movable portion descends; a trigger portion engaged with the support portion hammering resiliently when the support portion is released from the engagement; a piercing pin for perforating the seal mouth of the gas cylinder when the trigger portion is restored elastically; and a discharging manifold for guiding the discharge to the airbag of the gas ejected from the gas cylinder that is perforated by the piercing pin.

2. The airbag system according to claim 1, wherein the movable portion includes: a movable lever coupled flexibly to the support portion by means of the hinge, and elongated in the direction of the opposite side having a fitting hole in the center of one side; and a movable plumb attached under the other side of movable lever.

3. The airbag system according to claim 1 , wherein the support portion includes: a sub base having a shaft reception stand protruding to couple with one end of the movable lever with the hinge; a guide aperture on one side; a mounting groove on the other side of the guide aperture; and a bearing guide plate with a vertical inner face formed under the shaft reception stand, to bolt onto a main base, whereby a spring is mounted into the mounting groove of the sub base, and a guide pin passing through the fitting hole of the movable lever to guide the spring so the lower end secured to the center of the mounting groove of the sub base; a fixing holder rolling along the bearing guide plate of the sub base, said fixing holder including: a pair of support bearings rolling along the vertical inner face of the bearing guide plate of the sub base; a locking bearing provided at an opposite end of the supporting bearings, and fixing the fitting recess of piercing trigger selectively; and a fixing hole formed between the support bearings and locking bearing of the fixing holder, and an ascent/descent rod with a rounded top passing through the guide aperture of the sub base, and, assembled to the fixing hole of the fixing holder for sliding along the fixing hole horizontally, said the ascent/descent rod includes: a groove on its upper region; a fitting flange extending outward, spaced downward a distance from the groove; and a fitting groove located under the fitting flange, to be assembled to the rectangular fixing hole formed on the center of the fixing holder.

4. The airbag system according to claim 1, wherein the trigger portion includes: a piercing trigger having a spring fixing protrusion at one side of its front; a bearing fitting recess formed at the opposite corner; a striking end 743 bent from one side of its rear end to a specific position of the other side; and a shaft aperture 741 provided at the center of the striking end; and a first firing spring and a second firing spring divided into two parts, vertically spaced a distance that allows a shaft aperture of a piercing trigger to be located in the middle thereof, having upper fitting projections protruding up, and lower fitting projections protruding down, and integral fitting parts extending horizontally from a portion that vertically spaces the two firing springs, respectively: a support cover with plate-shaped fixing a central shaft under the first and second firing springs, having a boss with a fixing hole is formed on the center of its bottom; and a central shaft allowing the shaft aperture of the piercing trigger to rotate a selected distance from top of shaft in order to fix the trigger portion fitted on the center of the first and second firing springs, on the main base, having its upper portion which is different from lower portion in length, and coupling apertures of a specific depth which are formed in its upper and lower portions, respectively.

5. The airbag system according to claim 1. wherein the piercing pin includes: a rounded striking end; a fitting flange formed in the outer circumference at a position predetermined distance from striking end, wherein a spring presses; an inlet pipe with a sloping end having opening and vent holes radially on the inlet pipe outer surface.

6. The airbag system according to claim 1. wherein the discharging manifold includes: a connector having: a gas cylinder connection threading onto the gas cylinder; a piercing pin guide aperture formed horizontally therein, for guiding the piercing pin as it slides horizontally; and a gas aperture formed vertically over the piercing pin guide aperture, guiding the gas ejected from the gas cylinder 96 upward, a coupler having a hole on its top connected up the installation aperture of a lower cover, to thread onto the four corners of the connector, and a lower cover forming a pair of rectangular, recessed diffusion chambers, the diffusion chamber having an installation aperture at one side; a gas ejector including an ejection aperture formed at its center, that passes serially through the installation aperture of the lower cover and the hole of coupling member before inserted into a gas guide aperture of the connector, and a coupling flange by which it passes through the installation aperture of the lower cover, before mounting on and coupling under the lower cover; and a upper cover with the same area as the lower cover's top, having two gas discharging holes formed at locations corresponding to respective centers of the diffusion chambers, two guiding plates that slope, in a different direction, upward from the inside of the respective gas discharging nozzles, which guide a discharged gas jet in different directions, and an airbag attachment line around the gas discharging nozzles.