JP3267546B2 - Gas generator and airbag device for airbag - Google Patents

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 airbag which protects an occupant from an impact, and more particularly to a gas generator for an airbag which is characterized by its operation performance.

[0002]

2. Description of the Related Art When a vehicle such as an automobile collides at a high speed, an inertia is used to prevent a passenger from smashing into a hard part inside the vehicle, such as a steering wheel or a front glass, to prevent injury or death. Quickly inflates the bag with gas,
An airbag system is installed to prevent passengers from hitting dangerous places.

[0003] Such an airbag system can be used even if the occupant's physique (for example, a person with a high or low sitting height, an adult or a child, etc.), or his / her riding posture (for example, a posture holding on to a steering wheel) is different. It is desirable that the occupant can be restrained safely. Therefore, conventionally, an airbag system has been proposed which operates in the early stage of operation with as little impact as possible on the occupant.

[0004] In Japanese Patent Application Laid-Open No. Hei 8-207696, gas is generated in two stages, the bag is inflated relatively slowly in the first stage, and gas is rapidly generated in the second stage.
The use of capsules of different types of gas generating agents has been proposed, but has the drawback that the structure inside the gas generator is complicated, the size of the container becomes large, and this increases the cost.

Also, in US Pat. No. 4,998,751 and US Pat. No. 4,950,458, two combustion chambers are provided to regulate the operation function of the gas generator, and the gas generating agent is burned in two stages. It has been proposed, but its structure is complicated and not yet sufficient.

[0006]

SUMMARY OF THE INVENTION The present invention, while having a simple structure, operates in the initial stage of operation with as little impact on the occupant as possible and in a subsequent operation stage. An object of the present invention is to provide a gas generator for an airbag that can surely protect a passenger.
For example, in a gas generator for the driver's seat, the inflation speed of the airbag during 10 ms from the start of operation of the gas generator is made slower than before, and the occupant is sufficiently restrained after 30 to 50 ms. It is an object of the present invention to provide an airbag gas generator exhibiting such an operation performance.

[0007]

The gas generator for an air bag according to the present invention has a structure as described later, in which a seal tape closing a gas discharge port is ruptured at an early stage of gas generator operation. The impact on the occupant in the initial stage can be suppressed, and the above object can be achieved.

That is, the gas generator for an air bag according to the present invention comprises:
In a housing having a gas outlet, a single ignition means operated by impact, a gas generating agent ignited by the ignition means to burn and generate combustion gas, and a cooling and / or combustion residue of the combustion gas The combustion gas generated as a result of the operation of the ignition means is discharged as it is through the filter means, and there is no other than the filter means in the flow path of the gas. It can be realized as a gas generator for an airbag. Here, the filter means has not only a conventional filter for purifying a combustion gas by combustion of a gas generating agent, but also a coolant for cooling the gas, and a combination of these two functions (that is, a gas purification and cooling function). Coolant filters are also included.
In such a gas generator of the present invention, for example, an inner cylinder member is disposed in a housing, an ignition means accommodating chamber is defined inside, and a combustion chamber is defined outside, and the ignition means ignites a gas generating agent. In the case of a gas generator for an airbag including a burning charge, the filter means disposed around the combustion chamber is protected from the flame of the charge discharged from the through-hole of the inner cylinder member. Therefore, the coolant support (or coolant support member) disposed inside the filter means is provided at least in the gas flow path from the through hole to the gas discharge port.
It needs to be formed so as not to be an obstacle. When the ignition means is constituted by the igniter and the transfer charge, the combustion gas generated due to the operation of the ignition means corresponds to the combustion gas from the transfer charge ignited and burned by the operation of the igniter. I do.

The housing is defined by an inner cylinder member having a plurality of through holes as an ignition means accommodating chamber and a gas generating agent combustion chamber, and the ignition means accommodating chamber is defined inside the inner cylinder member. A igniting means operated by impact is provided in the chamber, and a gas generating agent ignited by the igniting means and burns to generate a combustion gas is provided in a gas generating agent combustion chamber defined outside the inner cylinder member. In the case of a gas generator for an airbag that contains a gas barrier, the flameproof plate is not provided on a straight line connecting the through hole and the gas outlet.

In the gas generating agent combustion chamber, there is further provided a filter means for cooling the combustion gas generated in the housing and / or collecting combustion residues, and an igniter operated by impact, and operation of the igniter In the case of a gas generator for an airbag in which an ignition means is constituted by a transfer charge that is ignited and burned, a gas such as a flameproof plate is placed on a straight line connecting the through hole of the inner cylinder member and the gas outlet of the housing. There is no member obstructing the flow of gas, and the combustion gas generated by the combustion of the transfer agent and the like ejected from the through-hole formed in the inner cylinder member in the housing passes through the filter means and is quickly gasified. It is formed so as to reach the outlet.

In order to prevent a short path of the combustion gas between the end face of the filter means and the inner face of the housing abutting on the end face, a circular portion for closing an end opening of the filter means is provided inside the filter means. When a short-path preventing means is provided, which is formed integrally with the circular portion and a peripheral wall portion abutting on the inner peripheral surface of the filter means, the short-path preventing means has a peripheral wall portion that is at least the through hole. It is necessary to regulate so as not to block the line connecting the gas outlet with the gas outlet.

In the gas generator for an air bag in which the filter means is disposed in the housing, it is preferable that a gap is further formed between the outside of the filter means and the inner surface of the peripheral wall of the housing.

A gas generator for an air bag according to the present invention has a single ignition means which is activated by an impact in a housing having a gas discharge port, and a gas generator which is ignited by the ignition means and burns to generate a combustion gas. The housing further contains filter means for cooling the combustion gas and / or collecting combustion residues, if necessary.

The housing having the gas discharge port can be formed by casting, forging, pressing, or the like. Preferably, the diffuser shell having the gas discharge port and the closure shell having the ignition means receiving port are welded. Formed. The two shells can be joined by various welding methods, for example, electron beam welding, laser welding, TIG welding, prosection welding and the like. When the diffuser shell and the closure shell are formed by pressing various steel plates such as a stainless steel copper plate, both shells can be easily manufactured and the manufacturing cost can be reduced. Further, by forming both shells into a simple and simple cylindrical shape, the press working thereof is facilitated. As for the material of the diffuser shell and the closure shell, a stainless steel plate is preferable, but a nickel-plated steel plate may be used. Moreover, after arranging an inner cylinder member in this housing to define a space in the housing into two or more rooms,
Each member can be appropriately accommodated.

[0015] In addition, it is preferable to use an electric ignition type ignition means which is operated by an electric signal transmitted from an impact sensor which senses the impact, as the single ignition means operated by the impact. The electric ignition type ignition means includes an electric sensor that senses an impact mainly by an electric mechanism, an igniter that operates with an electric signal transmitted from the sensor that senses the impact, and an ignition / ignition device that operates by the igniter. Combustion powder.
As this electric sensor, for example, there is a semiconductor type acceleration sensor. In this semiconductor type acceleration sensor, four semiconductor strain gauges are formed on a beam of a silicon substrate which bends when an acceleration is applied, and these semiconductor strain gauges are bridge-connected. When acceleration is applied, the beam bends, causing surface distortion. Due to this distortion, the resistance of the semiconductor strain gauge changes, and the resistance change is detected as a voltage signal proportional to the acceleration. In particular, the electric ignition type ignition means can further include a control unit having an ignition determination circuit. In this case, a signal from the semiconductor type acceleration sensor is input to an ignition determination circuit, and when the shock signal exceeds a certain value, the control unit starts calculation, and when the calculation result exceeds a certain value, gas generation occurs. Outputs an operation signal to the vessel.

If necessary, the filter means housed and arranged in the housing is provided with a housing for the purpose of removing the residue and / or cooling the combustion gas when a combustion residue is generated by the combustion of the gas generating agent. It is arranged in.
If a gas generating agent that does not generate combustion residues is used,
This filter means can be omitted. This filter means is often substantially cylindrical and is located outside the location where the gas generant is stored. Examples of such a material include a conventionally used filter for purifying generated gas and / or a coolant for cooling generated gas, and a wire mesh made of an appropriate material is formed into an annular laminate, and compression molded. A laminated wire mesh filter or the like can also be used.
More specifically, with respect to the laminated wire mesh filter, a flat knitted stainless steel wire mesh is formed in a cylindrical body, and one end of the cylindrical body is repeatedly bent outward to form an annular laminated body. Compression molding in the inside, or a flat knitted stainless steel wire mesh is formed in a cylindrical body, this cylindrical body is pressed in the radial direction to form a plate, and the plate is wound into a cylindrical shape in multiple layers. A laminate can be formed and then molded by compression molding in a mold. As the material of the wire mesh, stainless steel such as SUS304, SUS310S, and SUS316 (JIS standard symbol) can be used. SUS304 (18Cr-8N
i-0.06C) stainless steel shows excellent corrosion resistance as an austenitic stainless steel. The filter means may also be of a double structure having a layer of laminated wire mesh inside or outside. The inner layer may have a filter means protection function of protecting the filter means from the flame of the ignition means ejected toward the filter means and the combustion gas of the gas generating agent ignited and burned by the flame. The outer layer also prevents swelling of the filter means so that the filter means does not swell due to gas pressure during operation of the gas generator and does not block the gap formed between the filter means and the housing peripheral wall. It can function as a deterrent. The function of suppressing the swelling of the filter means can also be realized by supporting the outer periphery of the filter means with an outer layer made of a laminated metal mesh, a porous cylinder, an annular belt or the like.

In the present invention, it is particularly preferable to use a non-azide gas generating agent as the gas generating agent. As the non-azide gas generating agent, those comprising the following nitrogen-containing compound, oxidizing agent, slag forming agent and binder are preferable. Further, the following slag forming agent can be blended as required.

Examples of the nitrogen-containing compound include one or a mixture of two or more selected from the group consisting of a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, and a hydrazine derivative. Specific examples of these include 5-oxo-1,2,4-triazole, tetrazole, 5-aminotetrazole, 5,5′-
Bi-1H-tetrazole, guanidine, nitroguanidine, cyanoguanidine, triaminoguanidine nitrate,
Examples thereof include guanidine nitrate, guanidine carbonate, biuret, azodicarbonamide, carbohydrazide, carbohydrazide nitrate complex, oxalic acid dihydrazide, and hydrazine nitrate complex.

Among these nitrogen-containing compounds, one or more selected from the group consisting of a tetrazole derivative and a guanidine derivative are preferable, and particularly, nitroguanidine,
Preferred are cyanoguanidine and 5-aminotetrazole, and most preferred is nitroguanidine because of the small number of carbon atoms in the molecule. There are two types of nitroguanidine: needle-like crystalline low-density nitroguanidine and bulk crystalline high-density nitroguanidine.Either of them can be used. The use of specific gravity nitroguanidine is preferred. The proportion of the nitrogen-containing compound in the gas generating agent varies depending on the number of carbon elements, hydrogen elements and other oxidized elements in the molecular formula, but is usually preferably in the range of 25 to 56% by weight, and more preferably 30 to 40% by weight. %
Is particularly preferred.

Although the absolute value of the compounding ratio of the nitrogen-containing compound differs depending on the type of the oxidizing agent in the gas generating agent, if it is larger than the theoretical amount of complete oxidation, the concentration of trace CO in the generated gas increases, and the theoretical amount of complete oxidation and Below that, trace NOx in the generated gas
The concentration increases. Therefore, the range in which the optimum balance between the two is maintained is most preferable.

As the oxidizing agent used for the gas generating agent, various ones can be used, and an oxidizing agent selected from at least one of nitrates containing a cation selected from alkali metals or alkaline earth metals is preferable. . An oxidizing agent other than nitrate, that is, an oxidizing agent widely used in the field of airbag inflators such as nitrite and perchlorate may also be used, but the number of oxygen in nitrite molecules is reduced as compared to nitrate, or the amount outside the bag is reduced. Nitrate is preferred from the viewpoint of, for example, reducing the generation of fine mist that is easily released to the air. Examples of the nitrate containing a cation selected from alkali metals or alkaline earth metals include sodium nitrate, potassium nitrate, magnesium nitrate, strontium nitrate, and the like, with strontium nitrate being particularly preferred. The mixing ratio of the oxidizing agent in the gas generating agent varies in absolute value depending on the type and amount of the gas generating compound used, but is preferably in the range of 40 to 65% by weight, particularly in relation to the above-mentioned CO and NOx concentrations. A range of 45-60% by weight is preferred.

The function of the slag forming agent to be mixed as required is to release an oxide of an alkali metal or an alkaline earth metal generated by the decomposition of the oxidizer component in the gas generating agent to the outside of the inflator as a mist. In order to avoid this, it is a function to change from a liquid state to a solid state and stop it in the combustion chamber, and it is possible to select a slag forming agent optimized by a difference in metal components. Specific examples of the slag forming agent include acid clay, silica, bentonite-based, kaolin-based aluminosilicate and other naturally occurring clays, and synthetic clays such as synthetic mica, synthetic kaolinite, and synthetic smectite. And hydrous magnesium silicate mineral 1
Examples include slag forming agents selected from at least one species such as talc, and among these, acidic clay or silica is preferred, and acidic clay is particularly preferred.

For example, the viscosity and melting point of an oxidized mixture in a ternary system of calcium oxide generated from calcium nitrate, aluminum oxide and silicon oxide, which are main components in clay, are in the range of 1350 ° C. to 1550 ° C. depending on their composition ratios. The viscosity changes from 3.1 poise to about 1000 poise, and the melting point changes from 1350 ° C to 1450 ° C depending on the composition. By utilizing these properties, the slag forming ability corresponding to the mixture composition ratio of the gas generating agent can be exhibited. The mixing ratio of the slag forming agent in the gas generating agent can be changed in the range of 1 to 20% by weight, but is preferably in the range of 3 to 10% by weight. If the amount is too large, the linear burning rate and the gas generation efficiency will decrease. If the amount is too small, the slag forming ability cannot be sufficiently exhibited.

The binder is an essential component for obtaining a desired molded product, and any binder may be used as long as it exhibits viscosity in the presence of water and a solvent and does not have a significant adverse effect on the burning behavior of the composition. It is possible. Specific examples of such binders include metal salts of carboxymethyl cellulose, hydroxyethyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, and polysaccharide derivatives such as starch. Among them, a water-soluble binder is preferred from the viewpoint of production safety and ease of handling, and a metal salt of carboxymethyl cellulose, particularly a sodium salt, is the most preferred example. The compounding ratio of the binder in the gas generating agent is preferably in the range of 3 to 12% by weight, and more preferably in the range of 4 to 12% by weight. The larger the amount, the stronger the fracture strength of the molded body, but the larger the amount, the greater the number of carbon elements and hydrogen elements in the composition, and a small amount of CO gas, which is an incomplete combustion product of carbon elements Is undesirably increased because the concentration of the gas increases and the quality of the generated gas deteriorates. Particularly, when the amount exceeds 12% by weight, the relative proportion of the oxidizing agent needs to be increased, and the relative proportion of the gas generating compound decreases,
It is difficult to establish a practical gas generator system.

Further, when a sodium salt of carboxymethylcellulose is used as a binder, as a secondary effect, a micro-mixed state of a molecular order of sodium nitrate generated by a metal exchange reaction with a nitrate during the production of a molded body using water. The effect of improving the flammability is to shift the decomposition temperature of nitrate, which is an oxidizing agent, particularly strontium nitrate having a high decomposition temperature, to a lower temperature side.
Preferred gas generating agents used in the practice of the gas generator for airbags of the present invention include: (a) about 25-56% by weight, preferably 30-40% by weight nitroguanidine; (b) about 40-65% by weight; Preferably 45 to 65% by weight of oxidizing agent (c) about 1 to 20% by weight, preferably 3 to 10% by weight of slag former (d) about 3 to 12% by weight, preferably 4 to 12% by weight of binder Particularly preferred compositions include: (a) about 30 to 40% by weight nitroguanidine (b) about 40 to 65% by weight6 strontium nitrate (c) about 3 to 10% by weight A gas generant comprising acid clay or silica and (d) about 4 to 12% by weight of sodium salt of carboxymethylcellulose.

The gas generating agent is desirably formed in a perforated molded body such as a single-hole cylindrical shape or a porous cylindrical shape. Particularly, the value of the inner diameter d of the hole is 0.2 to 1.5 (mm).
When the length is L, the value of L / d is 3.
Desirably, it is 0 or more. This is because when the perforated molded body is ignited by the thermal energy of the ignition system, the ratio of the internal surface area that is initially ignited to the total internal surface area of the inner diameter portion is controlled. The part that is not ignited in the early stage immediately shifts to the ignited state due to the amount of heat generated in the ignited part. Therefore, only the initial ignition stage can be controlled without a time delay until the maximum pressure is reached. It should be recognized that this technique is fundamentally different in this respect from the so-called depower technique in which the overall gas generation output is reduced by a margin and the initial stage is controlled. Therefore, the gas generating agent of the perforated molded body such as the single-hole cylindrical shape or the porous cylindrical shape may be in a single-hole state, or as a result of a small single-hole state aggregate as a result of the control. The shape is not limited as long as the shape can be obtained, but a single hole state is preferable from the viewpoint of molding cost. The value of the inner diameter d of the hole is 0.2
1.51.5 mm, preferably 0.4-1.0 mm. If the value of d is less than 0.2 mm, the initial ignition area of the inner surface of the perforated molding due to the heat energy of the ignition system is insufficient, and the desired result cannot be obtained. , Heat energy reaches the initial ignition combustion area, and a desired gas generation output cannot be obtained. In addition, the value of L / d of the perforated molded product is 3.0 or more. However, if L is too long, the filling efficiency in a desired gas generating container is reduced. It should be determined, the preferred range of the value of L / d is 3.0 to 10.0
It is. If the value of L / d is less than 3.0, the gas generation behavior cannot be controlled as described above. The length L of the porous molded body of the present invention is not particularly limited, but is preferably 1.5 to 30 mm. The outer diameter D is not particularly limited, but is preferably 2.0 to 5.0 mm.

The preferred gas generating agent moldings of the present invention include: (a) about 25-56% by weight nitroguanidine; (b) about 40-65% by weight oxidizing agent; (c) about 1-20% by weight. A composition comprising about 3 to 12% by weight of a binder;
It is formed into a single-hole cylindrical shape.

In the gas generator of the present invention, structures and members advantageous for operating the gas generator can be appropriately adopted. Advantageous structures and members for the operation of the gas generator include, for example, a filter supporting member which is disposed between an inner cylindrical member defining an ignition means accommodating chamber and a filter means and supports the filter means. A "short path prevention means" surrounding the upper end and / or lower end of the inner periphery of the filter means and preventing generated gas from passing through a gap between the filter means and the inner surface of the housing; Alternatively, there are a "cushion member" disposed below to prevent the movement of the gas generating agent, and a "gap" secured between the outer surface of the filter means and the inner surface of the side wall of the housing to function as a gas flow path.

However, in the gas generator for an air bag according to the present invention, since the purpose is to allow the combustion gas to flow quickly, the adoption of a structure or a member that obstructs the flow of the gas should be avoided. It is.

The above-described gas generator for an air bag is housed in a module case together with an air bag (bag body) that introduces and inflates the gas generated by the gas generator to form an air bag device.

In this airbag device, the gas generator operates in conjunction with the impact sensor sensing the impact, and discharges the combustion gas from the gas outlet of the housing. This combustion gas flows into the airbag, which breaks the module cover and bulges, forming a shock absorbing cushion between the rigid structure and the occupant in the vehicle.

[0032]

FIG. 1 is a longitudinal sectional view of one embodiment of a gas generator for an air bag according to the present invention.

The gas generator shown in this figure has a housing 3 comprising a diffuser shell 1 and a closure shell 2.
The inside is defined by an inner cylinder member 16 into two chambers, an ignition means housing chamber 23 and a gas generating agent combustion chamber 28. In the ignition means accommodating chamber 23, ignition means (ignition means including the igniter 4 and the transfer charge 5 in this embodiment) for igniting and burning the gas generating agent 6 by being actuated by an impact is accommodated. In the combustion chamber 28, a gas generating agent 6 that is ignited and burned by the ignition means to generate combustion gas is disposed. The diffuser shell 1 can be formed by any of casting, forging, pressing, and the like. In this embodiment,
Stainless steel sheet is formed by pressing. The diffuser shell 1 has a circular portion 12, a peripheral wall portion 10 formed on the outer periphery of the circular portion 12, and a flange portion 19 extending radially outward at a tip end of the peripheral wall portion 10. . In the present embodiment, the gas outlets 3 having a diameter of 3 mm are arranged at equal intervals in the circumferential direction on the peripheral wall portion 10, and the gas outlets 11 are
It is closed by the seal tape 52. The diffuser shell 1 has a circular step 12 formed at the center of the circular section 12 by a reinforcing step 49 so as to protrude outward.
49 provides rigidity to the housing 3, especially to the circular diffuser shell 12 forming the ceiling thereof, and increases the volume of the accommodation space. A transfer charge container 53 containing the transfer charge 5 is sandwiched between the projecting circular portion 13 and the igniter 4. The flange portion 19 of the diffuser shell 1 has a mounting portion 98 for mounting the pad module to a mounting bracket. The mounting portion 98 is disposed at an interval of 90 degrees in the circumferential direction of the flange portion 19, and has a mounting hole 99 for screwing.

The closure shell 2 can be formed by casting, forging, pressing, or the like, similarly to the diffuser shell 1. In this embodiment, a stainless steel plate is pressed and formed. The closure shell 2 has a circular portion 30 and a central hole 15 formed in the center thereof.
And a peripheral wall portion 47 formed on the outer peripheral portion of the circular portion 30, and a flange portion 20 extending radially outward at a distal end portion of the peripheral wall portion 47. The central hole 15 has an axial bent portion 14 at the edge of the hole. The bent portion 14 provides rigidity to the hole edge of the central hole 15 and provides a relatively large joint surface with the inner cylindrical member 16. The inner cylindrical member 16 is arranged so as to fit in the central hole 15. Diffuser shell 1
The flanges 19 and 20 are overlapped with each other near the position on the center cross section in the axial direction of the housing 3, and the two are joined by laser welding 21.
Is formed. These flange portions 19 and 20 provide rigidity to the housing, particularly to the outer peripheral wall 8, and prevent deformation of the housing due to gas pressure.

In this embodiment, as described above,
A substantially cylindrical inner cylinder member 16 is disposed in the housing, the inside of which is the ignition means housing chamber 23, and the outside is the gas generating agent combustion chamber 28.
And The inner cylindrical member 16 can be formed by any of casting, forging, pressing, cutting, or the like, or a combination thereof. In the case of forming by press working, for example, a UO press system (a plate is formed into a U shape, then formed into an O shape, and a seam is welded) or an electric resistance welded tube system (a plate is formed into a circular shape, And welding with a resistance current by applying a large current while applying pressure. A caulking portion 27 is formed at the end of the inner cylinder member 16 on the side that houses the igniter 4.
Igniter 4 is fixed. The peripheral wall of the inner cylinder member 16 has a through hole 54 for the combustion chamber 28. In the case of the present embodiment, six through-holes having a diameter of 2.5 mm are arranged at equal intervals in the circumferential direction, and the through-holes are closed with a seal tape 52 '. The inner cylinder member 16 has an outward flange 38 formed at an end thereof welded to the inner surface of the projecting circular portion 13 of the diffuser shell 1.

In the present embodiment, ignition of the gas generating agent 6
In order to purify and cool the gas generated by the combustion, a coolant filter 7 is arranged in the housing 1 surrounding the gas generating agent 6, and an annular chamber around the inner cylinder member 16, that is, a gas generating agent combustion chamber Define 28. The coolant filter 7 has a stainless steel flat knit wire mesh superposed radially,
It is compressed radially and axially. The coolant filter 7 thus formed has a shape in which a loop-shaped stitch is crushed in each layer, which forms a layer in the radial direction. Therefore, the coolant / filter 7 not only cools the generated combustion gas, but also has an excellent trapping effect because the void structure becomes complicated.
Regarding the coolant filter 7, besides,
A well-known filter conventionally used for purifying gas by combustion of a gas generating agent, a well-known coolant used for cooling the gas, and the like can also be used. However, the coolant filter 7 may be omitted when a gas generating agent that does not generate combustion residues even when burned and does not need to cool the combustion gas is used. The coolant / filter 7 is prevented from moving by an inclined portion 31 formed in a circumferential direction surrounding the circular portion 30 of the closure shell 2, so that the coolant / filter 7 is securely located between the outer peripheral wall 8 of the housing 3 and the coolant / filter 7. A gap 9 is formed in the gap. The gap 9 functions as a gas flow path.

In an ignition means accommodating chamber 23 defined inside the inner cylinder member 16 provided in the housing 3, an electric ignition type ignition means comprising the igniter 4 and the transfer charge 5 is provided. Are arranged.

The gas generating agent 6 is solid and is contained in the gas generating agent combustion chamber 28. In this embodiment, the gas generating agent is a non-azide gas generating agent, in particular, a solid gas generating agent composed of nitroguanidine, Sr (NO ₃ ) ₂ , carboxymethyl cellulose and acid clay, A gas generating agent having a composition weight ratio of nitroguanidine: Sr (NO ₃ ) ₂ : carboxymethylcellulose: acid clay = 35.4: 49.6: 10: 5, nitroguanidine, Sr (NO ₃ ) ₂ , sodium carboxymethylcellulose It consists of salt and acid clay, and its composition weight ratio is nitroguanidine: Sr
(NO ₃ ) ₂ : a sodium salt of carboxymethyl cellulose: acid clay = 31.5: 51.5: 10: 7 can be used as a gas generating agent. The gas generating agent 6 is in the form of a hollow cylinder, and the length of one gas generating agent is L (m
m), when the inner diameter of the hole of the molded body is d (mm), the value of d is 0.2
It is regulated to 1.5 (mm) and the value of L / d is 3.0 or more. Due to this shape, the combustion takes place on the outer and inner surfaces, with the advantage that the surface area of the entire gas generant does not change much as the combustion proceeds.

In the gas generator of the present invention, the combustion gas generated by the combustion of the transfer charge 5 ejected from the through hole 54 of the inner cylinder member 16 is
A member having a flameproof plate that impedes rapid combustion gas flow so as to reach the sealing tape 52 that quickly closes the gas discharge port 11 and rupture the sealing tape 52 is not used or is not used. It is necessary that the length of the flameproof plate is limited to a length that does not hinder the flow of the combustion gas. That is, the member that hinders the flow of the combustion gas, except for the coolant filter 7, is in the flow path until the combustion gas generated from the through hole 54 formed in the cylindrical member 16 is discharged to the gas discharge port 11. not exist.

The gas generator shown in FIG. 2 is different from the gas generator shown in FIG. 1 in that the movement of the coolant filter 7 is prevented and the combustion gas flows between the coolant filter 7 and the inner surface of the diffuser shell 1. The coolant support member for preventing a short path passing therethrough is restricted to a length that does not hinder the rapid flow of the combustion gas, and is disposed inside the filter means.

In the gas generator shown in FIG. 2, in order to prevent the coolant / filter 7 from moving and to prevent a short path in which the combustion gas passes between the coolant / filter 7 and the inner surface of the diffuser shell 1, Combustion chamber 28
The coolant support member 32 disposed inside the diffuser shell 1 includes an annular portion 36 that surrounds the outward flange 38 of the inner cylinder member 16 and abuts against the inclined portion 49,
36, a flameproof plate, that is, a wall portion 34, which is in contact with the inner surface of the coolant / filter 7;
The wall portion 34 in 32 has a through hole 54 of the inner cylinder member 16 and a gas exhaust port.
The length α is regulated so as not to block the line γ connecting to 11.

In the gas generator shown in FIG. 2, a partition member 110 which deforms and / or displaces and / or breaks or burns the gas generating agent combustion chamber 28 by burning the gas generating agent is further provided. The gas generating agent accommodating chamber 24 and the space 100 are defined, and the gas generating agent accommodating chamber 24 and the space 100 are formed to communicate with each other by combustion of the gas generating agent. As a result, a more remarkable effect can be obtained.

In the gas generator shown in FIG. 1 or 2, the flow of the combustion gas generated by the operation of the ignition means, specifically, the flow of the combustion gas resulting from the combustion of the transfer charge 5 discharged from the through hole 54 is changed by a coolant filter. Since it is not hindered by members other than 7, the gas can quickly reach the gas outlet 11, and the seal tape 52 closing the outlet 11 can be ruptured at an early stage of gas generator operation. That is, in this gas generator, the transfer charge 5 ejected from the through hole 54 of the inner cylindrical member 16 is used.
The combustion gas (or flame) ignites the gas generating agent 6 near its flow path and quickly reaches the seal tape 52 that closes the gas discharge port 11. At the initial stage of the gas generator operation, the seal tape Burst 52. Then, the flame of the gas generating agent 6 ignited by the combustion gas ejected from the through hole 54 ignites the gas generating agent 6 in the vicinity thereafter, and generates a large amount of combustion gas. After passing through the coolant filter 7, the combustion gas generated by the combustion of the transfer charge 5 and the gas generating agent 6 passes through the gap 9 formed outside the filter 7, and is discharged from the gas discharge port 11. in this case,
The gap 9 functions as a gas flow path.

As a result, in spite of the simple structure, the operation can be performed with as little impact on the occupant as possible in the early stage of operation, and the occupant can be reliably protected in the subsequent operation stage. It becomes a gas generator for airbags.

In FIG. 2, the same members as those described with reference to FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 3 shows an embodiment of the airbag apparatus of the present invention in the case of including a gas generator using an electric ignition type ignition means.

This airbag device is composed of a gas generator 200
, An impact sensor 201, a control unit 202, a module case 203, and an airbag 204. The gas generator 200 uses the gas generator described with reference to FIG. ing.

The impact sensor 201 can be composed of, for example, a semiconductor acceleration sensor. In this semiconductor type acceleration sensor, four semiconductor strain gauges are formed on a beam of a silicon substrate which is deflected when an acceleration is applied,
These semiconductor strain gauges are bridge-connected.
When acceleration is applied, the beam deflects, causing strain on the surface. Due to this strain, the resistance of the semiconductor strain gauge changes, and the resistance change is detected as a voltage signal proportional to the acceleration.

The control unit 202 has an ignition determination circuit, and a signal from the semiconductor type acceleration sensor is input to the ignition determination circuit. When the shock signal from the sensor 201 exceeds a certain value, the control unit 202 starts the calculation, and when the calculation result exceeds a certain value, outputs an operation signal to the igniter 4 of the gas generator 200.

The module case 203 is made of, for example, polyurethane and includes a module cover 205. The module case 203 houses the airbag 204 and the gas generator 200 and is configured as a pad module. When the pad module is mounted on the driver's seat side of an automobile, the pad module is usually mounted on the steering wheel 207.

The airbag 204 is made of nylon (for example, nylon 66) or polyester, and its bag opening 206 surrounds the gas outlet of the gas generator, and is fixed to the flange of the gas generator in a folded state. Have been.

When an impact is detected by the semiconductor acceleration sensor 201 at the time of a vehicle collision, the signal is sent to the control unit 202, and when the impact signal from the sensor exceeds a certain value, the control unit 202 starts calculation.
When the calculated result exceeds a certain value, an operation signal is output to the igniter 4 of the gas generator 200. Thereby, the igniter 4 operates to ignite the gas generating agent, and the gas generating agent burns to generate gas. This gas is blown into the airbag 204, whereby the airbag breaks the module cover 205 and bulges, forming a cushion between the steering wheel 207 and the occupant to absorb impact.

[0053]

The gas generator for an air bag according to the present invention operates by applying as little impact as possible to the occupant in the initial stage of operation, and then rapidly inflates the air bag. Provided is a simple and structured gas generator for an airbag which can surely protect an occupant.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a gas generator according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the gas generator of the present invention.

FIG. 3 is a configuration diagram of an airbag device of the present invention.

[Explanation of symbols]

 Reference Signs List 3 housing 4 igniter 5 transfer agent 6 gas generating agent 7 coolant / filter 12, 30 circular portion 24 gas generating agent storage location 28 gas generating agent combustion chamber 100 space portion 110 partition member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60R 21/26 B60R 21/16

Claims (5)

(57) [Claims] 1. A housing having a gas discharge port is defined by an inner cylinder member having a plurality of through holes into an ignition means housing chamber and a gas generating agent combustion chamber, and is defined inside the inner cylinder member. A single igniting means operated by impact is disposed in the igniting means accommodating chamber, and a gas generating agent combustion chamber defined outside the inner cylinder member is ignited and burned by the igniting means. What is claimed is: 1. A gas generator for an airbag, comprising a gas generating agent containing a combustion gas and containing a gas generating agent, wherein the gas generating agent combustion chamber further cools a combustion gas generated in a housing and collects a combustion residue. A short path preventing means for preventing a short path of the combustion gas between an end surface of the filter means and an inner surface of the housing abutting on the filter means. Is arranged The short-path preventing means includes a circular portion for closing an end opening of the filter device, and a peripheral wall portion formed integrally with the circular portion and in contact with an inner peripheral surface of the filter device. It is regulated so as not to block at least a line connecting the through hole and the gas outlet, and is provided so that the opening direction of the through hole and the opening direction of the gas outlet are on the same plane. A gas generator for an airbag, comprising: 2. The gas generating agent combustion chamber further contains filter means for cooling at least one of combustion gases generated in the housing and collecting combustion residues, and the single ignition means is provided by an impact. It consists of an igniter that operates and a transfer charge that ignites and burns by the operation of the igniter,
The combustion gases from the combustion of the transfer charge ejected from the through hole, a gas generator for an air bag according to claim 1, wherein to reach quickly the gas outlet passes through the filter means. 3. The gas generator for an air bag according to claim 2, wherein the seal tape closing the gas discharge port is ruptured by a combustion gas generated by combustion of the transfer charge ejected from the through hole. The wherein in said housing, a gas generator for an air bag according to any one of claim 1 to 3, a gap is formed between the outer and the housing peripheral wall inner surface of the filter means. 5. A gas generator for an airbag, an impact sensor that senses an impact to activate the gas generator, an airbag that expands by introducing gas generated by the gas generator, and the airbag. And a module case for accommodating the airbag, wherein the gas generator for an airbag is the gas generator for an airbag according to any one of claims 1 to 4 .