JPH06227357A - Gas generator for air bag - Google Patents

Abstract

PURPOSE:To operate a gas generator before the material of housing is deteriorated in time of a fire in a car by installing each material with a firing point lower than that of a gassing agent and a transfer charge, in plural pieces of vessels to be set up an interval in the axial direction of the housing. CONSTITUTION:At the time of a fire in a car, if a housing is heated, this heat is transferred to a vessel yet nearer to the heated part so that AIM 13 in the vessel ignites. When this AIM13 in a transfer charge vessel 11 is set on fire, a transfer charge 10 ignites whereby a gassing agent 5 also ignites. In addition, when the AIM 13 in an AIM vessel 14 takes fire, high temperature gas is generated by this ignition, and this gas breaks a wall of the AIM vessel 14 and is blown out, propagating in a transfer tube 3, and the gassing agent 5 is ignited from the opening 19.

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 for protecting an occupant from an impact, and more particularly to a device for enabling its automatic ignition.

[0002]

2. Description of the Related Art There is a gas generator housing made of aluminum. In the event of a fire in a vehicle equipped with an airbag device, the gas generator may be heated to high temperatures, which may result in deterioration of the housing aluminum. If the gas generant ignites in this state,
There is a risk of the housing breaking or bursting. Therefore, for the purpose of activating the gas generator before the deterioration phenomenon occurs and avoiding such a danger, a substance that is ignited at a relatively low temperature in the gas generator (called an auto ignition material, abbreviated as AIM). May be placed.

For example, US Pat. No. 4,561,675 discloses that one gas generator is provided with one or two automatic igniters (a configuration in which an AIM is incorporated in a container). There is. U.S. Pat. No. 456167
No. 5 discloses an automatic ignition device arranged in the igniter chamber, and FIG. 4 discloses an automatic ignition device arranged in the combustion chamber.

[0004]

All of the above-mentioned conventional automatic ignition devices are arranged on one side of the housing and are limited to the central portion on one side, so that they are concentrated in a region away from this part. When the housing is heated,
It is possible that M will not catch fire. Therefore, the housing material (aluminum) is exposed to high temperature and deteriorates, and there is a risk that the housing is destroyed when the gas generating agent is ignited.

Therefore, it is an object of the present invention to provide a novel gas generator for an air bag that solves the problems of the prior art.

[0006]

SUMMARY OF THE INVENTION A gas generator for an air bag according to the present invention comprises a cylindrical housing having a gas outlet, and a transfer tube disposed in the housing and extending in the axial direction of the housing. A gas generating agent disposed around the fire transfer tube, an igniter fixed to one end of the housing and disposed in the fire transfer tube, and disposed in contact with the igniter. A gas generator that has a transfer charge container filled with transfer charge inside and protects an occupant from a shock by introducing a gas generated from the gas generation agent into the airbag by a shock. It is characterized in that a substance having an ignition point lower than that of the explosive is arranged in a plurality of containers arranged at a distance in the axial direction of the housing.

Further, it is preferable that the container is a container having good heat conductivity, which is fixed to the transfer charge container and the other end portion of the housing and is disposed in the transfer tube.

In the present invention, the AIM, that is, the substance that ignites at a low temperature is arranged in a plurality of containers spaced apart in the axial direction of the housing. This material has a lower flash point than the gas generant and transfer charge.

The ignition temperature of the transfer charge is as high as 343 ° C., for example, and there is a possibility that the aluminum in the housing has already deteriorated when the transfer charge is ignited during a vehicle fire. AI
Since M has a lower ignition point than the gas generant and the transfer charge, M can be ignited to ignite the gas generant and operate the gas generator before the aluminum deteriorates.

The container in which the AIM is disposed can be a transfer charge container located at one end of the housing and a container located at the other end of the housing. According to this
The AIMs will be arranged at both ends of the housing, and the AIM closer to the heating portion will ignite, and the gas generator can be operated. In addition to this, for example, it is also possible to arrange at three locations including a container located at the center of the housing. In this case too, the AIM closest to the heating section ignites and the gas generator can be activated to avoid the risk of housing damage.

The material of the container may be one having a high thermal conductivity, such as aluminum or steel.
Further, it is desirable that the container is placed in contact with the housing so that the heating state of the housing can be quickly detected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the present gas generator. This gas generator can be used as a gas generator for a passenger seat, and has a cylindrical housing 1 whose both ends are closed. The housing 1 has a plurality of discharge ports 6 in the region on the occupant side through which the combustion gas of the gas generating agent is ejected. A flame transfer tube 3 is arranged in the housing 1 coaxially with the housing over the entire length of the housing, and a combustion chamber 8 is defined by an inner cylinder 2 on the outer side of the flame transfer tube 3. Further, a filter chamber 17 is defined outside the combustion chamber 8 by the peripheral wall portion of the housing. In the combustion chamber 8, an annular gas generating agent 5 is fitted on the outer surface of the transfer tube 3.
Are arranged side by side, and a filter 7 is arranged in the filter chamber 17 so as to surround the gas generating agent 5. Inside the transfer tube 3, an igniter 9 which is activated by a signal from a sensor (not shown) and a transfer charge 10 which is ignited by the igniter 9 are loaded. The igniter 9 is held by an adapter 22, which is screwed onto one end 18 of the housing. The transfer charge 10 is contained in a transfer charge container 11 made of aluminum, and the transfer charge container 11 and the igniter 9 are in contact with each other.

The transfer tube 3 has a large number of openings 19 through which the flame of the transfer charge 10 is ejected, and the inner cylinder 2 is also provided with a plurality of openings 4 through which the combustion gas of the gas generating agent is ejected.

A substance having an ignition point lower than that of the gas generant 5 and the transfer charge 10, that is, an auto ignition material (hereinafter referred to as AIM) 13, is disposed in the transfer charge container 11 and the AIM container 14. ing. The AIM 13 is mainly composed of nitrocellulose. The AIM container 14 is made of aluminum, abuts against and is fixed to the other end portion 20 of the housing, and is arranged in the transfer tube 3. Transfer charge container 11,
The AIM containers 14 are located at both ends of the housing at a distance from each other in the axial direction of the housing.

Not limited to this, for example, as shown by the one-dot chain line in FIG. 1, the annular container 21 may be arranged at the center of the housing so as to be arranged at three positions. In this case, the AIM is arranged in the container 21, the container 21 is placed on the sealed opening of the inner cylinder 2, and the foil seal breaks so that the inside of the container 21 and the combustion chamber 8 communicate with each other. To

Further, instead of the AIM container 14, the gas generating agent 5 ′ is placed in contact with the other end 20 of the housing and has a central hole and an outer diameter of the same size as the gas generating agent. It is also possible to arrange an annular container.

Next, the operation of the gas generator thus constructed will be described.

(1) During normal operation: When the sensor detects a shock, the signal is sent to the igniter 9 to activate the igniter 9,
As a result, the transfer charge 10 and the AIM 13 are ignited to generate a high-temperature flame. This flame penetrates the wall of the transfer charge container 11, propagates in the transfer tube 3, and is ejected from the opening 19. The ejected flame ignites the gas generating agent 5. Further, the flame propagating in the transfer tube also ignites the AIM 13 in the AIM container 14 by its heat. Gas is generated by the combustion of the gas generating agent 5, the gas is ejected from the opening 4 of the inner cylinder 2 and enters the filter chamber 17, and is cooled and purified while passing through the filter 7, and the cooled and purified combustion The gas flows into the airbag (not shown) through the outlet 6 of the housing. At this time, the airbag is inflated to protect the occupant from the impact.

(2) In case of vehicle fire: When the housing is heated, this heat is transferred to the container closer to the heated portion and the AIM 13 in the container is ignited in response to this heat. Transfer charge container 11
When the AIM 13 therein is ignited, the transfer charge 10 is ignited by it, thereby igniting the gas generating agent 5. In addition, the AIM 13 in the AIM container 14
When the gas is ignited, a high temperature gas is generated by the ignition, the gas ruptures the wall of the AIM container 14 and is ejected, propagates in the transfer tube, and is opened through the opening 19 to generate the gas generating agent
It is designed to ignite.

[0021]

Since the present invention is constructed as described above, even if any part of the housing is heated when a vehicle fires, it can be reliably caught and the gas generator is activated before the material of the housing is deteriorated. Therefore, the risk of breaking or rupturing the housing can be surely avoided.

[Brief description of drawings]

FIG. 1 is a sectional view of the present gas generator.

[Explanation of symbols]

 1 Housing 3 Fire Transfer Tube 5 Gas Generant 6 Discharge Port 9 Igniter 10 Transfer Charge 11 Transfer Charge Container 13 AIM 14 AIM Container 18 One Side End 20 Other Side End

Claims (2)

[Claims] 1. A cylindrical housing having a gas outlet, a fire tube disposed in the housing and extending in the axial direction of the housing, and a gas generating agent disposed around the fire tube. And an igniter fixed to one end of the housing and arranged in the transfer tube, and a transfer charge container arranged in contact with the igniter to fill transfer charge therein, A gas generator that protects an occupant from impact by introducing gas generated from the gas generating agent into an airbag by means of a substance having a lower ignition point than the gas generating agent and the transfer charge in the axial direction of the housing. A gas generator for an air bag, wherein the gas generator is arranged in a plurality of containers arranged at a distance. 2. The airbag according to claim 1, wherein the container is a container having good heat conductivity, which is fixed to the transfer charge container and the other end of the housing and is disposed in the transfer tube. Gas generator.