JPH063468A - Gas cooling/filtering structure of gas generator - Google Patents

Abstract

PURPOSE:To enable the making of a handy and inexpensive apparatus by filling a gas cooling/filtering chamber with a magnesium hydroxide fiber. CONSTITUTION:With the sensing of an impact, a sensor signal is sent to an ignition chamber 1 and an igniter 2 catches fire to generate a high temperature flame. The flame jets 3 out to ignite a powder gas generating agent 5 in a gas generation chamber 4. The generating agent 5 burns and a high temperature/ high pressure combustion gas generated flows into a gas cooling/filtering chamber 8 passing through an inflow port 6. The combustion gas flowing in is cooled and filtered while passing through magnesium hydroxide fibers 9 and further done while passing through a stainless steel screen 10. In this manner, the combustion gas cooled and filtered flows into an air bag 12 at an outflow port 11 and the bag 12 expands sharply to protect a crew from impacts. Here, the fibers 9 cool the high temperature combustion gas effectively because of heat absorbing property thereof and the polyamide bag 12 bulges out without being melted by the combustion gas cooled.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to gas cooling of a gas generator.
More particularly, the present invention relates to a gas cooling / filtering structure of a gas generator using an explosive gas generating agent.

[0002]

2. Description of the Related Art Explosive gas generating agents are stable, have long-term storability,
It is excellent in reliability, and because the gas generator using it is small and lightweight, it is widely used, for example, as a power source for a servomotor used in one shot or as a gas source for an inflation bag such as an airbag. .

[0003]

However, in the above explosive gas generator, the temperature of the generated gas is 1000 to 3000.
Since it is as high as ℃ and generates soot, it requires an expensive gas filter and gas cooling device. Therefore, the structure is complicated and the cost is disadvantageous.

Therefore, an object of the present invention is to solve the above problems of the prior art and to provide a simple and inexpensive gas cooling / filtering device.

[0005]

A gas cooling / filtering structure for a gas generator according to the present invention has a gas generating chamber and a gas cooling / cooling structure in an outer shell.
In a gas generator that defines a filtration chamber, the gas cooling / filtration chamber having an inlet and an outlet for combustion gas generated in the gas generation chamber, the gas cooling / filtration chamber being filled with magnesium hydroxide fibers Is characterized by.

The gas generator has a gas generating chamber and a gas cooling / filtering chamber defined in its outer shell, and the gas cooling / filtering chamber has an inlet and an outlet for combustion gas generated in the gas generating chamber. . In the gas cooling / filtering structure of the present invention, the gas cooling / filtering chamber of this gas generator is filled with magnesium hydroxide fibers.

The present inventor has previously invented a gas cooling agent using a chemical endothermic tablet, but this requires a tableting operation which requires a high degree of skill. Then, as a result of research on a coolant which does not require such an operation, it was found that the purpose can be achieved by using a fibrous mineral.

The chemical composition of this magnesium hydroxide fiber is l.Mg (OH) 2.mFe2O3.nSiO2,
Mg (OH) 2 is 80-90%, Fe2O3 is 6-8%, Si
O2 is 0.2-5%. The diameter of this fiber is 0.1
The main length is 10 μm and the length is 1 to 30 mm. Long fibers are preferred for use in the present invention.

The thermal properties of this magnesium hydroxide fiber are as follows.

FIG. 3 is a diagram showing the results of the differential calorimetric analysis, in which the vertical axis shows the heat input / output. In the figure, 300 ° C
The large endotherm starting from around and reaching a peak at 410 ° C. indicates endothermic decomposition of the hydroxyl groups of magnesium hydroxide.

FIG. 4 is a diagram showing the result of the thermobalance.
The vertical axis shows the increase or decrease in mass. In the figure, the weight reduction starts at around 300 ° C., and the abrupt weight reduction ends at 430 ° C.

As shown by these test results, the magnesium hydroxide fiber has a large endothermic action due to the chemical reaction caused by heating. Moreover, the melting point of this fiber is 1700 ° C., and it also has appropriate heat resistance. Furthermore, the mechanical strength of this fiber is 1000 MPa, which is as strong as glass fiber.

Therefore, due to the endothermic property of this magnesium hydroxide fiber, effective cooling of high-heat gas can be achieved. Further, due to the heat resistance and mechanical strength of this fiber, this hot gas can be effectively filtered. By filling the gas cooling / filtration chamber of the gas generator with magnesium hydroxide fibers having such properties,
A simple and inexpensive gas cooling / filtering device, which is the object of the present invention, can be realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which a gas generator having the present gas cooling / filtering structure is used in a vehicle airbag device. The gas generator 20 is used as a gas source for inflating the airbag 12. The gas generator 20 includes a cylindrical outer shell container 21 having a central axis in the vertical direction of the drawing and having both ends closed. The outer shell container 21 is made of stainless steel and has a diameter of 11
It has a size of cm and a thickness of 6 cm. The inside of the outer shell container 21 is defined by a partition 7 into a gas generation chamber 4 and a gas cooling / filtration chamber 8. These two chambers are arranged so as to overlap each other in the axial direction of the gas generator, the gas generation chamber 4 is arranged on the lower side of the drawing, and the gas cooling / filtration chamber 8 is arranged on the upper side thereof. Further, the airbag 1 is provided in the outer shell container on the gas cooling / filtration chamber 8 side.
2 is mounted in a folded state. This airbag 12
Is a polyamide bag having an internal volume of 70 l.

A cylindrical partition member 22 is provided at the center of the gas generating chamber 4.
The ignition chamber 1 is demarcated by the
Is loaded. Further, the cylindrical partition member 22 is provided with a plurality of ejection ports 3 for transmitting the flame of the ignition charge 2 to the gas generation chamber 4. The gas generating chamber 4 is filled with 100 g of explosive gas generating agent 5 based on sodium azide and iron oxide.

The gas cooling / filtering chamber 8 is provided with a combustion gas inlet 6 and an outlet 11. A plurality of inflow ports 6 are bored along the partition wall member 22 in the region outside the cylindrical partition wall member 22 in the partition wall 7, and the combustion gas generated in the gas generation chamber 4 passes through the inflow port 6 to cool the gas. It is designed to flow into the filtration chamber 8. A plurality of outlets 11 are provided in the circumferential wall base of the outer shell container 21 forming the gas cooling / filtering chamber 8 in the circumferential direction, and the combustion gas cooled / filtered in the gas cooling / filtering chamber 8 is Air bag 1 through outlet 11
It is designed to flow into 2.

The gas cooling / filtering chamber 8 is filled with 40 g of magnesium hydroxide fiber 9 having the above-described chemical composition, fiber diameter and length. Further, a stainless steel wire net 10 is provided around the outer periphery of the gas cooling / filtration chamber 8 so as to surround the magnesium hydroxide fiber 9.

When a sensor (not shown) detects an impact,
The signal is sent to the ignition chamber 1 and the ignition charge 2 is ignited to generate a high temperature flame. This flame is ejected from the ejection port 3 and ignites the explosive gas generating agent 5 in the gas generating chamber 4. As a result, the explosive gas generating agent 5 burns to generate high-temperature, high-pressure combustion gas. The combustion gas passes through the inflow port 6 and flows into the gas cooling / filtering chamber 8. The inflowing combustion gas is cooled and filtered while passing through the magnesium hydroxide fiber 9, and further cooled and filtered while passing through the stainless steel wire net 10. The combustion gas cooled and filtered in this manner flows. It flows into the airbag 12 from the outlet 11. This causes the airbag to inflate rapidly to protect the occupant from impact. The magnesium hydroxide fiber 9 effectively cools high-temperature combustion gas due to its endothermic property, and the polyamide airbag can be expanded without being melted by the cooled combustion gas.

FIG. 2 shows an example in which the gas generator having the present gas cooling / filtering structure is used in an explosive gas servo device. 1 and 2, the same reference numerals indicate the same constituent elements. The gas generator 30 is used as a power source for operating the gas servomotor 13. Gas generator 30
Is provided with a cylindrical outer shell container 31 made of stainless steel and having a central axis in the lateral direction of the drawing and closed at both ends. The inside of the outer shell container 31 is defined by a partition wall 7 into a gas generation chamber 4 and a gas cooling / filtration chamber 8. These two chambers are arranged in series in the axial direction of the gas generator, the gas generating chamber 4 is arranged on the left side of the drawing, and the gas cooling / filtering chamber 8 is arranged on the right side thereof. A gas servomotor 13 is mounted on the side wall portion 19 on one end side of the outer shell container adjacent to the gas cooling / filtration chamber 8.

The gas generating chamber 4 is filled with ammonium nitrate or a polyurethane-based explosive gas generating agent 5, and an igniter 20 is mounted on the surface of the gas generating chamber 4 facing the partition wall 7.

The gas cooling / filtering chamber 8 is provided with an orifice-shaped inlet 6 formed in the center of the partition wall 7 and an outlet 11 formed in the side wall 19 on one end side of the outer shell container. ing. The gas cooling / filtering chamber 8 is filled with the magnesium hydroxide fiber 9. Further, a stainless wire net 10 is arranged between the magnesium hydroxide fiber 9 and the side wall portion 19.

The gas servomotor 13 is used in one shot and has two servo cylinders 14a and 14b arranged in parallel.
And each servo piston 15a, 15b. Each servo piston has a through hole 16 in the axial direction, and has solenoid valves 40a and 40b at its outlet. Further, through holes 18 are formed in the partition plate 17 in the regions of the servo cylinders 14a and 14b.

A servo motor activation signal is sent to the igniter 20 to activate the igniter 20. As a result, the explosive gas generating agent 5 in the gas generating chamber 4 is ignited and combusted to generate high temperature and high pressure combustion gas. Combustion gas passes through the inlet 6 to cool the gas.
It flows into the filtration chamber 8. The combustion gas that has flowed in is cooled and filtered while passing through the magnesium hydroxide fiber 9, and further cooled and filtered while passing through the stainless steel wire net 10. Thus, the combustion gas cooled and filtered to 130 ° C. Spouts from the outlet 11. The ejected gas is injected into each servo cylinder through the through hole 18, but when the solenoid valve 40a is closed and the solenoid valve 40b is opened, the cylinder 14a is opened.
Since the gas pressure inside becomes higher than the pressure inside the cylinder 14b, the piston 15a is pushed downward (to the right in the drawing).

Solenoid valve 40a according to the required torque pattern
And 40b are alternately opened and closed, the pistons 15a and 1
5b moves up and down, and a required torque is generated on the torque shaft 50.

If the combustion gas is not sufficiently cooled, the magnet used in the electromagnetic coil of the servo device will reach a temperature above the Curie point, and as a result, the servo device will not operate. In the gas generator having the present gas cooling / filtering structure, since the high temperature combustion gas can be effectively cooled by the endothermic property of the magnesium hydroxide fiber 9, such a problem does not occur and the present gas servo The motor 13 operated normally for 60 seconds during this period.

[0026]

The gas cooling / filtering structure of the present invention is characterized in that the gas cooling / filtering chamber is filled with magnesium hydroxide fiber.
A filter device can be realized.

Further, the gas generator provided with the present gas cooling / filtering structure can supply a sufficiently cooled gas by virtue of the excellent endothermic effect of the magnesium hydroxide fiber, so that it can be used as a power source for a servo motor. Alternatively, it can be applied without any problem as a gas source for an inflation bag such as an airbag.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example in which a gas generator having a gas cooling / filtering structure of the present invention is used in an airbag device.

FIG. 2 is a sectional view showing an example in which a gas generator having a gas cooling / filtering structure of the present invention is used in an explosive gas servo device.

FIG. 3 is a diagram showing the results of differential calorimetric analysis of magnesium hydroxide fibers.

FIG. 4 is a diagram showing the results of a magnesium hydroxide fiber thermobalance.

[Explanation of Codes] 4 Gas Generation Chamber 5 Explosive Gas Generation Agent 6 Inlet 7 Partition Wall 8 Gas Cooling / Filtration Chamber 9 Magnesium Hydroxide Fiber 11 Outlet 12 Airbag 13 Gas Servo Motor

Claims (1)

[Claims] 1. A gas generator in which a gas generating chamber and a gas cooling / filtering chamber are defined in an outer shell, and the gas cooling / filtering chamber is provided with an inlet and an outlet for combustion gas generated in the gas generating chamber. A gas cooling / filtering structure of a gas generator, wherein the gas cooling / filtering chamber is filled with magnesium hydroxide fiber.