JPH115507A - Gas generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas generator of high safety without depending on a complicated structure and decreasing also the limitation of layout relating to a vessel and system. SOLUTION: A bag inflating chamber is partitioned into a two-chamber structure by a burst plate 12, 13 able to burst by a pressure difference from the atmospheric pressure, to be respectively sealed with high pressure gas of nitrogen or the like. At time of operation, by an open tear means, a burst plate 11 most adjacent thereto is open torn, subsequently burst plates 12, 13 for the bag inflating chamber are open torn, and pressure accumulated gas is successively released to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generator, and more particularly, to a gas generator which is a main technology of an airbag system for restraining an occupant in the event of an automobile collision and reducing injuries to the occupant.

[0002]

2. Description of the Related Art As shown in FIG. 3, for example, a conventional gas generator for an air bag includes, as main components, a housing 1, a gas generating agent 2, a transfer agent 3, an ignition agent 4, filters 5 and the like. Consists of Among them, the gas generating agent is generally, for example, sodium azide (NaN ₃ ), and thermally decomposes according to the following formula to release nitrogen gas. As the NaN ₃ → Na + 3/2 · N ₂ igniting agent, an explosive ignited by an electric signal generated at the time of a vehicle collision, for example, a mixture of Zr and potassium perchlorate powder is used. The transfer agent is an explosive that increases the thermal power generated by the ignition agent and thermally decomposes the gas generating agent. Boron and potassium chlorate powder are often used. The filters are installed to suppress sodium, which is a reaction by-product of sodium azide, into the bag and the vehicle compartment as much as possible and to lower the gas temperature of generated gas.

[0003]

However, in order to better protect the occupants, it is conceivable to increase the output of the gas generator in multiple stages. In this case, gas generators using current explosives have different outputs. It is possible to use a system that has multiple generators and fires sequentially. However, there has been a problem that the structure is complicated and the cost is increased accordingly. In addition, there is a problem in that the layout of the container and the system is largely restricted due to the mechanism in which the gas generating agent is thermally decomposed to generate gas by transmitting the thermal power. An object of the present invention is to solve the problems of the prior art and to provide a highly safe gas generator which does not depend on a complicated structure and has few layout restrictions on containers and systems.

[0004]

According to the present invention, in order to solve the above-mentioned problems, a gas chamber stored for airbag deployment is divided into a plurality of chambers by a rupture plate having a strength capable of cleaving at a pressure difference from the atmospheric pressure. The chamber has a structure in which gas at substantially the same pressure is sealed.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a gas generator according to the present invention will be described in detail with reference to the accompanying drawings. FIG.
1 is a configuration diagram showing an embodiment of an internal structure of a gas generator according to the present invention. As shown in the figure, in the gas generator according to the present embodiment, the bag deployment chamber is divided into two chamber structures by rupturable plates 12 and 13 which can be ruptured by a pressure difference from the atmospheric pressure. And other high-pressure gases. In operation, the rupturable means 11 ruptures the rupturable plate 11 closest to the rupturable means, subsequently ruptures the rupturable plates 12, 13 in the bag deployment chamber, and releases sequentially stored gas to the outside.

As is apparent from the above configuration, when a collision is detected, the rupture means operates by energization, and ruptures the rupture plate of the opposing bag deployment chamber. First, when the gas sealed in the chamber close to the outside is almost released, a differential pressure between the atmospheric pressure and the sealing pressure is further applied to the rupturable plate partitioning the expansion chamber, and the rupturable plate also ruptures. As a result, the accumulated gas is sequentially released, and the output characteristic has two stages. Of course, the number of partitions for the gas chamber for bag deployment is not limited to two, and more than two rupturable plates for partitioning may be used in order to achieve more multi-stage deployment depending on required performance.

Next, more specific examples of the gas generator according to the present embodiment will be described with reference to comparative examples and test examples.

(Embodiment 1) A rupturable plate 12 provided with a thin portion so as to be cleaved at 200 atm is welded and sealed in a pressure vessel 14 made of a high-strength steel pipe having one end sealed, and has a capacity of 400 cm ^3. And a rupturable plate 13 was set in the chamber structure so that the volume became approximately half. The breaking strength of the rupture disk was 90 atm. Nitrogen gas was sealed at 100 atm in each chamber structure partitioned in the expansion chamber. In addition, a rupturing means was provided opposite to the rupturable plate 12 in the bag inflation chamber. The cleaving means is provided in a pressure vessel made of a high-strength steel pipe having one end sealed.
The rupturable plate 11 provided with a thin portion so as to be cleaved at atm is welded and sealed, a chamber structure is provided so as to have a volume of 50 cm ^3, and a nichrome wire having a wire diameter of 0.3 mm is arranged in the expansion chamber. And used as a cleavage means. At this time, hydrogen 3
0 volume%, oxygen 15 volume%, and nitrogen 55 volume% were sealed at a total pressure of 50 atm.

Example 2 The procedure was the same as in Example 1 except that two rupturable plates were provided so as to divide the expansion chamber into three equal parts.

(Example 3) The procedure was the same as in Example 1, except that explosives were used as the cleavage means.

(Comparative Example) A gas generator for the driver's seat for the current domestic market was used.

(Test Example) FIG. 2 is a graph when the gas generators shown in Examples 1 to 3 and Comparative Example were evaluated by the following test method. << 60-liter tank test >> A gas generator is housed in a pressure-resistant container having a capacity of 60 liters, gas is generated in the container, and the pressure-time change in the container at that time is monitored. As shown in FIG. 2, in the first to third embodiments, there is no sharp increase in pressure as in the comparative example, and it can be seen that the pressure increases in multiple stages. Therefore, it is possible to provide a highly safe gas generator that better protects the occupant.

[0013]

As described above in detail, according to the present invention, the gas chamber stored for the deployment of the airbag is divided into a plurality of chambers by a rupturable plate which is ruptured at a pressure difference from the atmospheric pressure. The interior of the chamber was filled with gas at almost the same pressure.
Therefore, it is possible to increase the number of stages of the output of the gas generator without using a complicated structure and with almost the same layout restrictions as before.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a gas generator according to the present invention.

FIG. 2 is a graph showing test results of an embodiment of the present invention and a conventional technique.

FIG. 3 is a diagram illustrating a configuration of a conventional airbag gas generator.

[Explanation of symbols]

 11, 12, 13 bursting plate 14 pressure vessel

Claims (5)

[Claims] 1. A gas generator of an occupant protection device intended to protect an occupant in the event of a collision, wherein the gas generator has a chamber structure partitioned by a rupturable plate which can be opened by pressure. A gas generator comprising: a bag inflation chamber having a structure having a rupturable rupturable plate which is divided into a plurality of rupture plates; 2. The gas generator according to claim 1, wherein the rupturable plate provided for dividing the bag inflation chamber has a strength to rupture at a pressure difference between the sealed gas and the atmospheric pressure. Generator. 3. The gas generator according to claim 1, wherein the rupturable means of the rupturable plate of the bag inflation chamber is partitioned by a rupturable plate which can be ruptured by the generated pressure, and has an ignition source. A gas generator having a structure in which a flammable gas is sealed in the gas generator. 4. The gas generator according to claim 3, wherein the combustible gas sealed in the cleavage means is a mixed gas of hydrogen and oxygen. 5. The gas generator according to claim 4, wherein the charged gas has a hydrogen concentration of 10 to 40% by volume of the total gas amount,
A gas generator having an oxygen concentration of 19 to 12.5% by volume of the total gas amount and a total filling pressure of 5 to 100 atm.