JPH0761315A - Gas generator for air bag - Google Patents

Abstract

PURPOSE:To simplify the manufacture of gas generator for air bag by reducing number of part items of a housing, and reducing points of bonding fixation. CONSTITUTION:A housing 1 consists of a shell 2 and a cover 3. In the shell 2, a cylindrical part 4 having a cover, which is opened toward one side, and an annular housing recessed part 5, which is opened toward the opposite side of the opening direction of the cylindrical part 4 in the periphery of the cylindrical part 4. An igniting mechanism 10 and gas generating agent 13 are housed inside of a combustion chamber 6, which is formed by the cylindrical part 4 of the shell 2 and a cover 3 for covering the opening end thereof. Cooling scavenger 17 is housed in of the housing recessed part 5 of the shell 2 under the exposed condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generator for an air bag mainly used for inflating and expanding an air bag such as an air bag, a life bag, a rubber boat, an escape chute as a safety device at the time of collision. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as a safety device for protecting an occupant from a shock at the time of a collision in a vehicle, especially a passenger car, an airbag device for instantaneously inflating an airbag at the time of a collision is known. This airbag device is composed of an airbag and a gas generator that generates gas for inflating the airbag. The airbag has a volume of 30 to 70 liters in the driver's seat device and 100 to 250 liters in the passenger seat device.

Further, most of the gas generators used especially in the airbag device for the driver's seat have to be housed in the pad cover at the center of the steering wheel, and are restricted in size and shape. It has a disk-shaped pressure vessel shape. When a passenger vehicle collides, the gas generating agent burns due to ignition of the ignition mechanism to generate gas, and the gas instantaneously inflates the airbag to protect the occupant from impact at the time of collision.

As a gas generator in an air bag device for a driver's seat of this type, for example, Japanese Patent Laid-Open No. 2-155857.
A structure as shown in Japanese Patent Publication has been conventionally known. That is, as shown in FIG.
Is formed by assembling a substantially covered cylindrical shell 22, a disc-shaped combustion chamber cover 23, and a substantially annular diffuser cover 24, and welding and fixing their joints. A combustion chamber 25 is defined in the center of the housing 21, and a diffuser chamber 26 is defined in the outer peripheral portion.

A plurality of disc-shaped gas generating agents 27 are housed and arranged in the combustion chamber 25 in a laminated state, and a through hole 27a is formed in the center thereof. The electric igniter 28 is disposed in the through hole 27 a of the gas generant 27 by screwing the attachment plug 29 into the combustion chamber cover 23. A powdery ignition agent 30 made of boron nitrate or the like is filled in the through hole 27a of the gas generating agent 27 in correspondence with the electric igniter 28. The cooling collectors 31 and 32 are the combustion chamber 25.
They are housed in the outer peripheral edge and the diffuser chamber 26, respectively.

When the electric igniter 28 is ignited by energization, the igniting agent 30 is burned and its flame is propagated to the gas generating agent 27. As a result, the gas generating agent 27 is burned and gas is generated in the combustion chamber 25. This gas is cooled by the cooling and collecting materials 31, 32, and the solid combustion residue is filtered. Then, the purified gas is flown outward through the gas outflow hole 33 of the diffuser cover 24 to inflate and deploy the airbag.

[0007]

However, in this conventional air bag gas generator, the housing 21 is used.
Is composed of three members of a shell 22, a combustion chamber cover 23, and a diffuser cover 24, which are assembled and fixed by welding their joints. For this reason, there is a problem that the structure of the housing 21 is complicated, the number of parts is increased, the number of joint fixing points is increased, the manufacturing is troublesome, and the weight of the entire gas generator is increased.

The present invention has been made by paying attention to the problems existing in the above conventional techniques. The purpose of this is to simplify the structure of the housing and reduce the number of parts, to reduce the number of joint fixing points and to simplify the production, and to reduce the size and weight of the entire gas generator. An object of the present invention is to provide a gas generator for an airbag that can be designed.

[0009]

In order to achieve the above-mentioned object, in the invention described in claim 1, an ignition mechanism for igniting, a gas generating agent for generating gas by combustion, and a generating mechanism are provided in a housing. In a gas generator for an air bag containing a cooling and collecting material for cooling the gas, the housing is composed of a shell and a cover, and the shell has a cylindrical portion with a lid that opens to one side, An annular accommodating recess is provided on the outer periphery of the tubular portion, the annular housing recess opening toward the opposite side to the opening direction of the tubular portion, and the combustion chamber formed by the cover that covers the tubular portion of the shell and the opening end thereof is provided with An ignition mechanism and a gas generating agent are housed, and the cooling trapping material is housed in an exposed state in a housing recess of the shell.

The invention according to claim 2 is characterized in that, in the airbag gas generator according to claim 1, the shell and the cover are formed by press working, and their joints are fixed by welding. It is what

[0011]

In the air bag gas generator of the present invention, the housing is composed of two members, a shell and a cover. Therefore, the structure of the housing is simple and the number of parts can be reduced. Further, when assembling the housing, since only one joint between the shell and the cover has to be fixed by welding or the like, the number of joints and fixing points is reduced, and the manufacturing can be simplified. Further, by integrating these, it is possible to reduce the size and weight of the gas generator as a whole.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air bag gas generator embodying the present invention will now be described in detail with reference to FIGS.

As shown in FIGS. 1 to 3, the gas generator housing 1 comprises a shell 2 and a cover 3. A cylindrical portion 4 having a cylindrical shape with a lid is formed at the center of the shell 2 and is open toward one side in the axial direction. The annular accommodation recess 5 is formed concentrically on the outer circumference of the tubular portion 4,
It is opened toward the side opposite to the opening direction of the tubular portion 4. The cover 3 is fitted into the open end of the tubular portion 4 of the shell 2 and fixed by welding.
The combustion chamber 6 is defined by the cover 3 and the cover 3.

A plurality of gas outflow holes 7 are formed in the peripheral wall of the tubular portion 4 of the shell 2, and the combustion chamber 6 is communicated with the housing recess 5 through the gas outflow holes 7. The mounting flange 8 is formed on the outer peripheral edge of the opening end of the housing recess 5, and the mounting flange 8 is provided with a plurality of bolt insertion holes 9 for mounting on a steering wheel of a vehicle.

The electric igniter 11 of the ignition mechanism 10 is fitted and fixed in the center of the cover 3 so as to be located at the center of the combustion chamber 6 of the housing 1, and the lead wire 12 is provided at the outer end thereof.
Are connected. A plurality of gas generating agents 13 are loaded in the combustion chamber 6 of the housing 1 via a sheet-shaped pressing member 14 so as to be located on the outer periphery of the electric igniter 11. Further, each gas generating agent 13 is formed into a rod shape having a circular cross section by extrusion molding or the like, and is aligned and arranged so as to extend in parallel along the axial direction of the housing 1.

As an extrusion molding method for the gas generating agent 13, there is, for example, the following method. That is, oxidizing agents such as perchlorates and nitrates, binders such as nitrocellulose, cellulose acetate and ethyl cellulose, plasticizers,
An appropriate amount of a solvent is added to a raw material composed of a combustion control agent and the like and uniformly mixed to prepare a drug mass. For example, a drug mass is prepared from raw materials of 63% by weight of potassium perchlorate, 12% by weight of cellulose acetate, 5% by weight of dimethyl phthalate, and 20% by weight of dihydrate of bitetrazole manganese salt.

This drug mass is loaded into a companding machine and pressure is applied,
By extruding through a die attached in advance to the companding machine, a rod having a predetermined outer diameter shape and outer diameter dimension is formed. Then, this molded product is cut into a predetermined length according to the dimensions of the housing 1 and then dried.

On the other hand, a circular sheet-shaped igniting agent 15 is disposed at one end of the combustion chamber 6 of the housing 1 and is in contact with one end surfaces of the electric igniter 11 and the gas generating agent 13.
The igniting agent 15 is formed, for example, by immersing a disk-shaped glass fiber sheet in a slurry-like chemical and then drying it. The plurality of rod-shaped gas generating agents 13 are sandwiched and held between the sheet-shaped igniting agent 15 and the pressing material 14.

Examples of the igniting agent 15 include 30% by weight of boron and 70% by weight of potassium nitrate to which an appropriate amount of binder is added, and 60% by weight of magnesium and 40% by weight of polytetrafluoroethylene. And the like. Then, by adding a solvent such as acetone to these compositions and stirring and mixing, a slurry state can be obtained.

The cooling scavenger 16 is arranged with a predetermined thickness on the inner surface of the peripheral wall of the combustion chamber 6 so as to surround the outer periphery of the gas generating agent 13. For example, a plain weave wire mesh made of stainless steel of 24 mesh is wound three times. Things are being used. The cooling collecting material 17 is housed in the housing recess 5 in an exposed state, and is fixed by a retaining ring 18 so as not to come off. The cooling and collecting material 17 has, for example, a wire diameter of 0.3.
A compression-molded 6 mm stainless steel knit wire is used. Then, the gas generated by the combustion of the gas generating agent 13 is cooled when passing through the cooling and collecting materials 16 and 17, and the solid combustion residue in the gas is filtered.

Next, the structures of the shell 2 and the cover 3 of the housing 1 will be described. Now, in this embodiment, the shell 2 and the cover 3 of the housing 1 are formed by press-molding a metal material that can be plastically worked. Examples of this material include stainless steel, titanium and titanium alloys, and aluminum alloys or magnesium alloys that have undergone heat treatment, that is, processing, heat treatment, or a composite treatment thereof.

These plastically workable metal materials have the property that they are hardened by press working or heat treatment and their strength is increased. Therefore, when this metal material is used, a predetermined strength can be secured even if the thickness of the shell 2 and the cover 3 is reduced. The thickness of the shell 2 and the cover 3 can be set within the range of 1.0 to 2.0 mm, preferably about 1.5 mm.

Incidentally, in this embodiment, stainless steel (Japanese Industrial Standard SUS304L) is used, and the thickness of the shell 2 and the cover 3 is set to 1.5 mm. This stainless steel is a preferable material because it has high strength and is work hardened by press working to further increase its strength. Therefore, according to this embodiment, the thickness of the shell and the cover can be considerably reduced as compared with the conventional configuration in which the thickness is set to 1.5 to 4 mm.

In particular, when the shell 2 and the cover 3 require corrosion resistance, light weight and strength, it is preferable to use titanium and titanium alloy. Also, especially shell 2
When the corrosion resistance, the light weight, and the ease of processing are required for the cover 3 and the cover 3, it is preferable to use a tempered aluminum alloy or magnesium alloy.

Next, the mounting structure of the electric igniter 11 to the cover 3 of the housing 1 will be described. As shown in FIGS. 1 and 4, a conical portion 3a is formed in the central portion of the cover 3 so as to be gradually reduced in diameter toward the combustion chamber 6 side, and combustion is performed from the inner end of the conical portion 3b. The cylindrical portion 3b is folded back toward the side opposite to the chamber 6. Further, a small diameter projecting portion 3c is provided at the folded portion between the conical portion 3a and the cylindrical portion 3b.

At the time of assembling the gas generator, the sheet-shaped igniting agent 15 is disposed in the tubular portion 4 of the shell 2 and the cooling trapping material 17 is accommodated in the accommodation recess 5.
A plurality of gas generating agents 13 are arrayed and supported on the cover 3 via a pressing material 14, and the gas generating agents 13 are also supported.
The cooling and collecting material 16 is circulated around the outer circumference of the.

In this state, the cover 3 is fitted to the open end of the tubular portion 4 of the shell 2, and the joints thereof are welded by electron beam welding, laser welding, or the like, and the cover 3 is attached to the shell 2. Fix in an airtight condition. This allows the shell 2
The housing 1 is formed of the cover 3 and the cover 3, and the gas generating agent 13 and the igniting agent 15 are housed in the combustion chamber 6 of the housing 1 in a contacting state.

After that, as shown in FIG. 4, the electric igniter 11 is inserted into the cylindrical portion 3b from the outside of the cover 3, and the large-diameter collar 11a of the igniter 11 is engaged with the projecting portion 3c. In this state, the outer edge of the cylindrical portion 3b is caulked along the large-diameter collar 11a of the igniter 11 to be plastically deformed, so that the igniter 11 is in contact with the ignition agent 15 in the combustion chamber 6, It can be fixed to the cover 3.

In this case, the seal ring 19 is interposed between the outer peripheral surface of the igniter 11 and the inner peripheral surface of the overhanging portion 3c, and the large diameter collar 11a of the igniter 11 and the caulking of the cylindrical portion 3b are caulked. A sealant (not shown) is applied between the parts. This allows the igniter 11 to be attached to the cover 3 in an airtight state.

In the air bag gas generator constructed as described above, when a detection signal is generated due to a vehicle collision or the like, a predetermined current flows through the electric igniter 11 through the lead wire 12, The igniter 11 is ignited. The sheet-shaped igniting agent 15 is burned by this ignition, and the flame of the sheet-shaped igniting agent 15 is in contact with the igniting agent 15.
Propagated directly to. Thereby, the plurality of gas generating agents 13
Are simultaneously ignited and burned to generate gas such as nitrogen gas in the combustion chamber 6. The gas passes through the gas outflow hole 7 and the combustion chamber 6
The air is discharged to the outside and is cooled and filtered by the cooling collecting materials 16 and 17 to inflate an airbag (not shown).

As described above, in the air bag gas generator of this embodiment, the housing 1 is composed of two members, the shell 2 and the cover 3. Therefore, the structure of the housing 1 is simple and the number of parts can be reduced. Further, when assembling the housing 1, only one joint between the shell 2 and the cover 3 may be fixed by welding. For this reason, the number of joint fixing points of the components of the housing 1 is reduced, and the manufacturing can be simplified. Furthermore, by combining these, it is possible to reduce the size and weight of the gas generator as a whole.

Further, in the airbag gas generator of this embodiment, the shell 2 and the cover 3 of the housing 1 are formed by press working, and their joints are fixed by welding. Therefore, the thickness of the shell 2 and the cover 3 can be reduced while the housing 1 maintains a predetermined strength, and the overall size and weight of the gas generator can be further reduced.

[0033]

Another Embodiment Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the conical portion 3a is formed in the central portion of the cover 3 by bending so that the diameter becomes gradually larger toward the combustion chamber 6 side, and the inner end of the conical portion 3b extends to the combustion chamber 6. The cylindrical portion 3b is formed so as to extend toward it. In addition, a small-diameter overhang 3c is provided at the bent portion of the conical portion 3a.

When mounting the electric igniter 11, the igniter 11 is inserted from the inside of the cover 3 into the cylindrical portion 3b, and the large-diameter collar 11a of the igniter 11 is extended.
engage c. In this state, the inner end edge of the cylindrical portion 3b is caulked along the large-diameter collar 11a of the igniter 11 to be plastically deformed, whereby the igniter 11 can be fixed to the cover 3.

The present invention is not limited to the configuration of the above-described embodiment, and may be embodied by making the following arbitrary changes without departing from the spirit of the present invention. (1) A mounting adapter made of another member is fixed to the central portion of the cover 3, and the igniter 11 is mounted on the mounting adapter. (2) Aluminum foil or the like is attached to the inner peripheral surface of the shell 2 to close the gas outflow hole 7 to prevent moisture inside the combustion chamber 6. (3) The rod-shaped gas generating agent 13 has a C-shaped cross section, a single-hole tubular shape having a through hole in the center, or a multi-hole tubular shape having a large number of holes. (4) As the gas generating agent 13, use a pellet-shaped material or a disk-shaped material. (5) It is possible to more reliably prevent the cooling collecting material 17 from popping out by providing the retaining rings 18 at a plurality of locations.

[0036]

Since the present invention is configured as described above, it has the following excellent effects.

According to the first aspect of the invention, the structure of the housing is simple, the number of parts can be reduced, and the number of joint fixing points can be reduced to simplify the manufacturing. The overall size and weight of the container can be reduced.

According to the second aspect of the present invention, the thickness of the housing can be reduced while maintaining a predetermined strength, and the size and weight of the entire gas generator can be further reduced. Can be planned.

[Brief description of drawings]

1 is a sectional view taken along the line AA of FIG. 3, showing an embodiment of a gas generator for an air bag embodying the present invention.

FIG. 2 is a front view of the gas generator.

FIG. 3 is also a plan view of the gas generator.

FIG. 4 is a partial cross-sectional view showing a mounting configuration of an electric igniter with respect to a cover.

FIG. 5 is a partial cross-sectional view showing another embodiment of the mounting structure of the electric igniter to the cover.

FIG. 6 is a cross-sectional view showing a gas generator having a conventional configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Shell, 3 ... Cover, 4 ... Cylindrical part, 5 ... Storage recessed part, 6 ... Combustion chamber, 10 ... Ignition mechanism, 11
… Electric igniter, 13… Gas generating agent, 15… Ignition agent, 16
... Cooling collecting material, 17 ... Cooling collecting material.

Claims (2)

[Claims] 1. A gas generator for an air bag, wherein an ignition mechanism for igniting a gas, a gas generating agent for generating gas by combustion, and a cooling trapping material for cooling the generated gas are housed in a housing. The housing is composed of a shell and a cover, and the shell has a cylindrical portion with a lid that opens toward one side, and an annular shape that opens toward the side opposite to the opening direction of the tubular portion on the outer periphery of the tubular portion. An accommodation recess is provided, the ignition mechanism and the gas generating agent are accommodated in a combustion chamber formed by a cover that covers the tubular portion of the shell and the opening end thereof, and the cooling trapping material is accommodated in the accommodation recess of the shell. A gas generator for an air bag, wherein the gas generator is housed in an exposed state. 2. The gas generator for an air bag according to claim 1, wherein the shell and the cover are formed by press working, and their joints are fixed by welding.