JPH0478745A - Gas generator - Google Patents

Abstract

PURPOSE:To decrease the thickness of a shell by providing a ring shell of a sectional crank type moulded in one body by pressing with a combustion chamber upper wall, a cooling collection chamber lower wall and a partition wall of both chambers, a cooling shell and a cover to form a combustion chamber. CONSTITUTION:A combustion chamber is arranged concentrically in the outer periphery of an igniter 1, and the gas generator in the title is constituted of an upper wall 11 of a shell of a sectional crank shape, a partition wall 15 and a cover 13. The outer peripheral part of the combustion chamber 9 forms a ring cooling collection chamber 14, and the inner end edge of a diffuser shell (cooling shell) 20 is welded on the upper part of the shell 10 and the lower end edge is welded on the outer end edge of the shell 10 so that the combustion chamber 9 is constituted. The shell 10, the diffuser shell 20 and the combustion chamber cover 13 are previously manufactured by press working, assembled and welded together. As the section is made in a crank shape and then they are integrated it is possible to improve pressure proof property by way of decreasing the thickness of the shell 10 and make the shell 10 excellent in mass productivity and in profitability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas generator (hereinafter simply referred to as a gas generator) for inflating an airbag that is attached to, for example, a steering wheel of an automobile and used for collision protection of occupants. (referred to as vessels).

[Conventional technology]

The construction of most conventional gas generators is shown, for example, in US Pat. No. 4,547,342.

This gas generator will be explained based on FIG. 2. Below the bottomed cylindrical housing 31 made of aluminum and open downward, there is a flange portion 32 which is also open upward.
A bottomed cylindrical lid 32 made of aluminum and having a diameter of 1.a is fitted and joined by friction welding. An ignition chamber 33 is formed in the center of the space formed by the housing 31 and the lid 32, and a squib 34 is erected at the center of the lower part of the ignition chamber 33. is filled with an ignition charge 36 that serves to ignite the gas generating agent 35 based on the heat generated by the squib 34. Note that the flange portion 32a is for attaching the scum generator to a base plate (not shown).

The combustion chamber 3 is connected to the outer periphery of the ignition chamber 33 via a partition wall 37.
8 is formed, and a plurality of openings 39 are transparently provided in the partition wall 37. This combustion chamber 38 is filled with a gas generating agent 35 in the form of pellets.

A cooling collection chamber 41 is provided on the outer periphery of the combustion chamber 38 via a partition wall 40, and communicates with the combustion chamber 38 through an opening 43 provided in the partition wall 40. Inside the cooling collection chamber 41 and the outer periphery of the combustion chamber 38, a cooling collection is provided to cool the gas generated by combustion decomposition of the gas generating agent 35 and at the same time to collect solid byproducts other than the generated gas. material 44 is loaded.

On the other hand, gas generators with a thin plate structure are also known (Special Publications Publication No. 6).
2-5094).

This gas generator will be explained based on FIG.

An igniter 51 is disposed in the center of the gas generator, a squib 52 is disposed at the bottom of the igniter 51, and an igniter 53 is filled in the upper outer periphery of the squib 52. This igniter 51
One end of a casing 54 made of aluminum and having an S-shaped cross section, which is integrally manufactured by cold working, is welded and fixed to the outer circumference of the side wall of the casing 54 using a laser beam. This casing 5
4 is formed with an S-shaped cross section, so from the viewpoint of strength, its thickness is about 2.5 mm compared to the conventional one.
By making the cooling collection chamber 55 portion U-shaped, the gas discharge port 56 is formed into a slit shape.

The casing 54 constitutes a lower wall 58 of the combustion chamber 57 and an upper wall 59 and side walls 60 of the cooling collection chamber 55. A cover 61 is welded and fixed between the upper part of the side wall 60 of the casing 54 and the igniter 51, and the combustion chamber 57 is configured, and a gas generating agent 6 is contained inside it.
3 is filled. This combustion chamber 57 communicates with the interior of the igniter 51 through an opening 64 in a side wall 62 of the igniter 51.

Further, an annular support fixing plate 65 is fixed to the lower part of the cooling collection chamber 55, and a cooling collection material 6 is provided in the cooling collection chamber 55.
6 is filled. The cooling collection chamber 55 communicates with the combustion chamber 57 through an opening 67 provided in the side wall 60 of the casing 54 .

[Problem to be solved by the invention]

Generally, among the performance requirements for a gas generator, weight reduction and mass production are among the most difficult. A handle with a built-in gas generator tends to be less stable in operation than a gas generator without a built-in gas generator. In addition, it is necessary to reduce the weight of the vehicle as much as possible in order to improve fuel consumption rate for the purpose of energy conservation.
It is desired that gas generators be made lighter.

Furthermore, in order to reduce injuries to drivers caused by accidents, it is desired that many automobiles be equipped with air pack systems. To achieve this, it is necessary to provide gas generators as inexpensively as possible.

However, in the case of the gas generator shown in FIG. 2, the ignition chamber 33, the combustion chamber 38, and the cooling collection chamber 41 are integrally formed of aluminum, so the wall thickness is required to increase the strength. There was a problem in that the weight increased and it was not possible to reduce the weight.

Furthermore, in the case of the gas generator shown in FIG. 3, since the S-shaped casing 54 is used, welding is performed by laser light rather than friction welding as in the gas generator shown in FIG. 2. Therefore, there is no need to increase the area of the welding surface, which reduces weight, but each member is thick and
Further, since the thickness of the welded portion is different, it cannot be press-formed, and since it is manufactured by cold forging, there is a problem that it lacks mass productivity. Further, the combustion chamber 57 is formed by welding the casing 54 and the cover 61, but since the cover 61 is provided in the deployment direction of the air pack 68, that is, on the driver's side, the welded portion There was a risk that the broken cover 61 would directly hit the driver and cause injury.

Pressed stainless steel has traditionally been used as a casing material for gas generators, but thick plates are used to withstand high combustion pressure, which poses problems in terms of weight reduction. Aluminum products are also used to reduce weight, but aluminum products have low strength, so they must be made thicker and the aluminum base material must be cold forged, and they require processing. In some cases, a post-heat treatment is performed, which makes it impossible to improve mass productivity, and therefore, there is a problem that the process is economically unsatisfactory.

An object of the present invention is to provide a gas generator that is lighter in weight than conventional gas generators, can be mass-produced at low cost, and does not pose any danger to the driver under any circumstances.

[Means to solve the problem]

In order to solve the above-mentioned conventional problems, the present inventors have investigated the structure of a gas generator from the viewpoints of the shape of the parts forming the gas generator, the method of coupling between parts, strength, workability, etc. After many years of study, we have discovered that the above-mentioned conventional problems can be solved by combining a specific shell, a differential user shell, and a lid, and have completed the present invention.

That is, the present invention includes an igniter, a combustion chamber which is arranged in an annular manner around the outer periphery of the igniter and stores a gas generating agent, and a cooling collection chamber which is arranged in an annular manner on the outside of the combustion chamber and stores a cooling collection material. a gas generator in which the igniter, the combustion chamber, and the cooling collection chamber are in communication with each other through an opening; an annular shell integrally formed with a lower chamber wall by press molding and having a crank-shaped cross section; a cooling shell having a gas discharge port and forming a cooling collection chamber with the shell; and a combustion chamber with the shell. The gist thereof is to include a cover that forms a.

[Effect]

In the gas generator of the present invention configured as described above,
For example, when a car equipped with a gas generating device collides, the collision detection device turns on the power to the gas generating device, ignites the igniter, and the flame propagates to the gas generating agent in the combustion chamber, causing the gas generating agent to burn. As combustion begins, the internal pressure of the combustion chamber increases. At that time, the structure of the shell is crank-shaped in cross section, in which the upper wall of the combustion chamber, the partition wall that partitions the combustion chamber and the cooling collection chamber, and the lower wall of the cooling collection chamber are integrally formed by press molding. It can sufficiently withstand gas pressure even if the shell is thinner than conventional shells.

Hot combustion gases and solid by-products generated in the combustion chamber pass through the opening into the cooling collection chamber. When passing through the cooling collection material, the combustion gas is cooled and solid by-products are collected, and the cooled gas is discharged from the gas outlet of the diffuser shell into the airbag to inflate and deploy the airbag.

〔Example〕

An embodiment embodying the present invention will be described below with reference to FIG.

An igniter 1 is arranged in the center of the gas generator.

An ignition chamber 4 is formed from a cylindrical igniter main body 2 having a flange portion 2a at the upper end of the igniter 1 and an ignition chamber cover 3 fitted to the lower part. A squib 5 is vertically fixed to the ignition chamber cover 3. A lead wire 6 is connected to the squib 5, and an ignition powder 7 is filled and coated around the upper part of the squib 5.

Further, a plurality of openings 8 are provided in the outer peripheral portion of the igniter main body 2, so that the ignition chamber 4 and a combustion chamber 9, which will be described later, communicate with each other.

An annular combustion chamber 9 is arranged concentrically around the outer periphery of the igniter 1. This combustion chamber 9 includes an upper wall 1 of a shell IO formed in a crank shape in cross section, a partition wall 15 that partitions the combustion chamber 9 and a cooling collection chamber 14 to be described later, and a lower combustion chamber cover 13 formed in an annular shape. The mounting portion 10a at the inner end of the shell 10O is disposed along the lower surface of the flange portion 2a of the igniter body 2 and is joined to the igniter body 2. cover 13
Its inner edge is joined to the lower outer periphery of the igniter main body 2, and its outer edge is welded to the lower part of the partition wall l5 of the shell 10. The shape of the shell 10 must be a cross section or a crank shape.

This shape is inappropriate because it has an S-shaped cross section and a thick thickness, as shown in the conventional Japanese Patent Publication No. 5094/1983, and if it is uneven, press molding cannot be performed.

The contact point between the combustion chamber cover 13 and the shell IO is welded using, for example, a laser or plasma welder. A case 17 containing a gas generating agent 16 is housed within the combustion chamber 9. Any conventionally known gas generating agent 16 can be used. For example, the gas generating agent 16 is made of a combination of an azide of an alkali metal or an alkaline earth metal such as sodium azide, and a metal oxide. Its shape may be, for example, pellet-like or disk-like. The gas generating agent 16 shown in FIG. 1 is in the form of pellets. Further, the partition wall 15 of the shell 10
An opening 19 is transparently provided in the combustion chamber 9 and the cooling collection chamber 14.
It communicates with

The shell 10 and the combustion chamber cover 13 may be made of any material that can be press-formed (in this example, stainless steel (product name YUS3 manufactured by Nippon Steel Corporation) is used.
01L) is used.

Stainless steel is work hardened by press forming,
It is an optimal material because of its property of increasing strength. Further, the thickness thereof is usually about 0.8 to 1 mm, and in this embodiment, one having a thickness of 1 mm is used. In addition, the thickness can be made considerably thinner compared to the conventional product, which has a thickness of 1.5 to 4 mm.

An annular cooling collection chamber 14 is formed on the outer periphery of the combustion chamber 9 so as to be concentric with the igniter l. The cooling collection chamber 14 has an inner edge of a diffuser shell 20 as a cooling shell having a cross-sectional shape similar to that of the shell 10.
The lower part of the diffuser shell 20 is welded to the outer edge of the shell 10 by welding using the same welding machine as described above. A cooling collection material 21 is disposed within the cooling collection chamber 14 . As this cooling collection material 21, for example, a filter made of metal and inorganic fibers is used.

A gas discharge port 22 is transparently provided on the upper outer periphery of the differential user shell 20, so that gas from the cooling collection chamber 14 is introduced into the air bag 23 on the outer periphery of the air bag 23 to inflate the air bag 23. It has become.

The material of this differential user shell 20 is
It is preferable to use a material that can be press-formed in the same way as the shell 1.
The same 1mm thick stainless steel as 0 is used.

The flange portion 20a of the differential user shell 20 includes:
A mounting hole 24 is provided through the mounting hole 24 so that the mounting hole 24 is fixed to the main body of a steering wheel (not shown) with a bolt. The shape of the gas generator is approximately 30 to 40 mm in height, and approximately 90 to 110 mm in diameter excluding the flange portion 20a.
It is set to about mm.

The gas generator of this embodiment configured as described above is manufactured as follows.

First, the shell 10, the differential user shell 20,
The combustion chamber cover 13 is manufactured by press working. Since these are all formed to have a uniform thickness, press working is easily performed. Cooling collection chamber 1 of this shell 10
The cooling collection material 21 is incorporated into the four parts, and the contact parts with the diffuser shell 20 are welded to form a pressure-resistant structure. Next, the aluminum case I7 containing the pellet-shaped gas generating agent 16 is loaded into the combustion chamber 9 side of the shell 10, the combustion chamber cover 13 is fitted, and the shell 10 and the combustion chamber cover 13
The contact area is welded to create a pressure-resistant structure. Finally, the igniter 1 is assembled into the igniter body 2 at the center of the gas generator, and the ignition chamber cover 3 is attached to obtain the gas generator.

The operation and effects of the gas generator configured as described above will be explained.

For example, when a sensor (not shown) installed in a car detects the severity of a collision, electricity is applied to the squib 5 via the lead wire 6, causing the squib 5 to generate heat and igniting the ignition charge 7 filled around its upper periphery. do. The flame and heat generated by the ignition of the igniter 7 are propagated from the opening 8 of the igniter body 2 into the combustion chamber 9, and the gas generating agent 16 housed in the case 17 in the combustion chamber 9 burns, producing nitrogen gas and other gas. of solid by-products.

These products enter the cooled collection chamber 14 through openings 19 provided in the partition wall 15 of the shell 10 separating the combustion chamber 9 and the cooled collection chamber 14 . In the cold collection chamber 14 the solid by-products are filtered by the cold collection material 21 . Then, only the nitrogen gas passes through the gas exhaust port 22 at the top of the cooling collection chamber 14, and the airbag 2 folded and accommodated in the outer periphery.
3 and the airbag 23 opens.

As described above, in the gas generator of this embodiment, the cross-sectional shape of the shell 10 is crank-shaped, and the upper wall 11 of the combustion chamber 9 and the partition wall 15 of the combustion chamber 9 and the cooling collection chamber 14 are connected to each other.
By integrating the lower wall 12, resistance to combustion pressure can be increased. That is, the thickness of the shell 10 can be reduced for a constant combustion pressure, and the weight of the scum generator can be reduced.

In addition, the combustion chamber 9 and the cooling collection chamber 14 are constructed from three parts: the shell 10, the diffuser shell 20, and the combustion chamber cover 13, and the thickness of each part is made uniform. Since the shell 10 can be easily press-formed and no heat treatment is required after processing, the scum generator can be mass-produced and is highly economical.

Further, the shell 10 forms the upper wall 11 of the combustion chamber 9, and is fixed to the igniter body 2 with the mounting portion 10a at the inner end of the shell 10 located on the lower surface of the flange portion 2a at the upper end of the igniter body 2. Therefore, the upper wall 11 can sufficiently withstand the combustion pressure within the combustion chamber 9, and therefore there is no risk of harm to the driver.

〔Effect of the invention〕

In the gas generator of the present invention, the cross-sectional shape of the shell is crank-shaped, and the upper wall of the combustion chamber, the partition wall of the combustion chamber and the cooling collection chamber, and the lower wall of the cooling collection chamber are integrated. It is possible to increase the resistance force and, conversely, to reduce the thickness of the shell for a given combustion pressure, making it possible to reduce the weight of the gas generator and to reduce the thickness of the combustion chamber and cooling collection chamber. , shell and differential user shell and lid 3
By being composed of one part, the shell can be easily press-molded, and furthermore, it does not require heat treatment after processing, making it excellent for mass production and economical efficiency.
Furthermore, by forming the upper wall of the combustion chamber with a shell, there is an excellent effect that no harm is caused to the driver under any circumstances.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a gas generator showing an embodiment of the present invention;
FIG. 2 is a sectional view showing a conventional gas generator, and FIG. 3 is a partial sectional view showing another conventional gas generator. ■...Igniter, 8...Opening, 9...Combustion chamber, 1
0...Shell, 11...Upper wall, 12...Lower wall, 1
3... Combustion chamber cover, 14... Cooling collection chamber, 15.
... partition wall, 16 ... gas generating agent, 19 ... opening,
20... Diffusion user shell as a cooling shell,
21... Cooling collection material, 22... Gas discharge port.

Claims (1)

[Claims] 1. An igniter (1), a combustion chamber (9) arranged annularly around the periphery of the igniter (1) and housing a gas generating agent (16);
A cooling collection material (2) is arranged in an annular shape on the outside of the combustion chamber (9).
1), and the igniter (1), combustion chamber (9) and cooling collection chamber (14) communicate with each other through openings (8, 19). In the gas generator, the upper wall (11) of the combustion chamber (9) and the combustion chamber (
9) and the partition wall (15) that partitions the cooling collection chamber (14) and the lower wall (12) of the cooling collection chamber (14) are integrally formed by press molding, and the annular shell (10) has a crank-shaped cross section. ) and a gas outlet (22).
0) and a cooling shell (2) forming a cooling collection chamber (14).
0); and a cover (13) forming a combustion chamber (9) with the shell (10).