JPH0752747A - Cold collecting filter and gas generator therewith - Google Patents

Abstract

PURPOSE:To enable a cold collecting filter to effectively cool the combustion gas produced by combustion of a gas generating agent, and to collect its combustion product surely without causing any clogging due to this product as well as to facilitate manufacture and enable the reduction of manufacturing cost. CONSTITUTION:This gas generator 1 consists of an ignition chamber 3 equipped with a squib 8, an igniting powder 10 or the like, a combustion chamber 5 equipped with a gas generating agent 12, and a cold collecting chamber 7 equipped with a cold collecting filter 17 cooling combustion gas and simultaneously collecting a combustion product. This filter 17 is provided with an inner knit wire molding 18, a ceramic fiber paper 19 and an outer knit wire molding 20 in order from the gas generated side after being unified in a body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling and collecting filter used in an airbag device for protecting an occupant mounted on an automobile, and a gas generator using the cooling and collecting filter.

[0002]

2. Description of the Related Art As a conventional gas generator, there is known one provided with the following cooling and residue collecting layer (Japanese Patent Publication No. 53-13411). That is, the cooling / residue trapping layer is made of silica, alumina, heat-resistant inorganic oxides such as silica-alumina, glass wool, metal wool, wire netting, etc., alone or in combination, and has a porosity that does not cause clogging. It is as thin as possible.

Further, the following secondary filter means arranged in contact with the secondary gas orifice means in the gas diffusion space in the gas generator is known (Japanese Patent Publication No. 1902/1990).
No. 0). That is, the secondary filter means, in order from the inside, has a multi-layered coarse wire net having a surface for cooling gas and condensing solid particles, and fine solid particle combustion residue is collected and reacted with sodium oxide particles to react with sodium silicate. A single layer or multiple layers of aluminum silicate cover to form,
It consists of fine wire mesh.

However, in these conventional gas generators, it is said that the cooling and collecting filter cannot sufficiently cool the gas passing therethrough or has a function of reliably collecting combustion residues. I could not say. Therefore, in order to enhance the cooling and collecting functions, the following technique has been disclosed (Japanese Patent Laid-Open No. 2-155861).

That is, the cooling collecting filter is one kind of a fine wire mesh or a cylindrical heat-resistant porous body, an inorganic fiber sheet, a sintered metal fiber cloth, a porous ceramic filter and a porous metal sintered filter. Or, two or more kinds, a tatami-woven wire mesh, and a fine wire mesh are provided. The fine wire mesh or the tubular heat-resistant porous body is wound multiple times in a tubular shape in order to cool the gas and to make the gas turbulent and disperse. The inorganic fibrous sheet is wound around the fine wire mesh or the cylindrical heat-resistant porous body to filter fine powder contained in the gas.

One or more kinds of the sintered metal fiber cloth, the porous ceramic filter and the sintered porous metal filter are wound adjacent to the inner side and the outer side of the inorganic fibrous sheet. To be destroyed by the gas flow. Tatami woven wire mesh is one or two of metal fiber sintered cloth etc.
It is wound on the outer side of one or more kinds to disperse the gas in a turbulent flow, and backs up the sintered metal fiber cloth or the like to improve the strength of the filter. The fine mesh is wound around the tatami mesh to improve the strength of the filter and cool the gas.

[0007]

However, in this prior art, in order to exert the functions of cooling and collecting and prevent the destruction of the inorganic fiber sheet, the metal fiber is complicated in the manufacturing process and high in manufacturing cost. It was necessary to arrange the sintered cloth and the like so as to sandwich the inorganic fiber sheet. Therefore, there are problems that the manufacturing of the gas generator becomes difficult and the manufacturing cost increases.

The present invention has been made by paying attention to the above conventional problems. The purpose of the cooling filter is to cool the combustion gas generated by the combustion of the gas generating agent, and to reliably collect the combustion gas without causing clogging by the combustion products. And to provide a gas generator using the same.
Another object of the present invention is to provide a cooling trapping filter which is easy to manufacture and whose manufacturing cost is reduced, and a gas generator using the same.

[0009]

In order to achieve the above object, in the cooling collection filter of the invention described in claim 1, a cooling collection filter that cools gas and collects solid residue in gas is used. It is characterized in that the knit wire molded product, the ceramic fiber paper, and the knit wire molded product are laminated in this order.

Further, in the gas generator of the invention as set forth in claim 2, the ignition chamber having the ignition means, the combustion chamber having the gas generating agent burned by the ignition means, and the combustion of the gas generating agent In a gas generator comprising a cooling collection chamber provided with a cooling collection filter that collects combustion products while cooling the generated combustion gas, the cooling collection filter is a knit wire molded product, and a ceramic fiber. It is characterized in that the paper and the knit wire molded product are sequentially laminated.

The cooling and collecting filter and the gas generator of the present invention will be described below with reference to FIGS. Figure 1
FIG. 3 is a vertical sectional view showing an example of the gas generator 1 of the present invention. As shown in the figure, an ignition chamber 3 is provided at the center of a disk-shaped housing 2, and a first partition wall 4 is provided around the ignition chamber 3.
The combustion chamber 5 is concentrically defined through the space. A cooling / collecting chamber 7 is concentrically defined on the outer periphery of the combustion chamber 5 via a second partition wall 6. A squib 8 is erected and fixed to the inner bottom of the ignition chamber 3, a lead wire 9 is connected to the squib 8, and an igniter 10 is filled and coated around the upper portion of the squib 8. The squib 8, the lead wire 9 and the igniting agent 10 constitute an ignition means.

A first communication hole 11 is formed through the first partition wall 4 to connect the ignition chamber 3 and the combustion chamber 5 to each other. In addition, a pellet-shaped gas generating agent 12 is housed inside the combustion chamber 5, and a combustion chamber filter 13 is arranged.

Further, a second communication hole 14 is provided through the second partition wall to connect the combustion chamber 5 and the cooling collection chamber 7 to each other, and a gas is provided on the outer peripheral wall of the cooling collection chamber 7. The ejection port 15 is provided so as to eject the gas in the cooling collection chamber 7 into the airbag 16 outside the gas generator 1. A cooling collection filter 17 is annularly arranged on the outer peripheral side of the cooling collection chamber 7 so as to cover the gas outlet 15.

As shown in FIG. 2, the cooling collection filter 17
Is formed in an annular shape. Further, FIG. 3 shows a cross section of the cooling collecting filter 17, and as shown in the figure, the cooling collecting filter 17 is, in order from the inner peripheral side, an inner knit wire molded product 18, a ceramic fiber paper 19, and an outer knit wire. A molded product 20 is arranged. Knit wire molding 18,
Reference numeral 20 is also called a sock woven wire mesh, and is basically a wire mesh composed of one wire.

The innermost inner knit wire molded product 18
For the purpose of cooling the combustion gas and combustion residues and diffusing the gas, a wire having a wire diameter of 0.20 to 0.40 mm is used. The wire diameter of the inner knit wire molded product 18 is 0.
If it exceeds 40 mm, the cooling and diffusion performance is insufficient, and if it is less than 0.20 mm, the inner knit wire molded product 18 is clogged, which is not preferable.

The material of the inner knit wire molded product 18 is selected from metals such as stainless steel, iron, nickel and aluminum or alloys thereof, and stainless steel or iron is preferable.

The outer knit wire molded product 2 on the outer layer side
0 is used for the purpose of collecting relatively small combustion residues by filtration and reinforcing the ceramic fiber paper 19 arranged on the inner periphery thereof. The wire diameter is 0.10-0.1
5 mm is preferred. When the wire diameter is less than 0.10 mm, since the outer knit wire molded product 20 is on the gas outflow hole 15 side, there is a possibility that it will jump out due to the outflow pressure of the gas.
If it exceeds 0.15 mm, it is difficult to collect a relatively small residue, which is not preferable.

Next, the ceramic fiber paper 19 contains fine combustion residues and metallic sodium (Na) and sodium oxide (N).
a ₂ O) is used for the purpose of filtering and collecting. The main component of this ceramic fiber paper 19 is silicon dioxide (SiO ₂ ).
And alumina (Al ₂ O ₃ ) fibers, which are made into paper with an organic or inorganic binder. The ceramic fiber paper 19 has a bulk density of 0.15 to 0.35 g / cm ³ ,
A fiber material having an air permeability of 3.0 to 8.0 sec / 300 cc, an average wire diameter of 1.0 to 4.0 μm, and a thickness of 0.5 to 5 mm, as shown in Japanese Industrial Standard JISP 8117. Is a filter of. The ceramic fiber paper 19 may be one containing fine metal fibers or glass fibers having a wire diameter of several μm in order to increase air permeability and tensile strength.

The bulk density of the ceramic fiber paper 19 is 0.1.
When the air permeability is less than 5 g / cm ³ or less than 3.0 seconds / 300 cc per 1 mm of thickness, the performance of capturing combustion residues, metallic sodium and sodium oxide is poor, which is not preferable. If the bulk density exceeds 0.35 g / cm ³ or the air permeability per 1 mm of thickness exceeds 8.0 sec / 300 cc, the collection performance is high, but the air permeability is high, so the cooling trapping is performed. This is not preferable because the internal pressures of the collecting chamber 7 and the combustion chamber 5 rise.

It is desirable that the knit wire molded products 18 and 20 and the ceramic fiber paper 19 are integrally formed by press molding from the viewpoint of easy accommodation in the cooling and collecting chamber 7.

[0021]

The cooling and collecting filter of the present invention is constructed by laminating a knit wire molded product, a ceramic fiber paper, and a knit wire molded product in this order, and is mounted on a gas generator or the like. Then, the gas passing through the cooling and collecting filter is cooled and the solid residue in the gas is collected.

Further, in the gas generator, for example, when a vehicle equipped with the gas generator collides, the collision detection device turns on the gas generator to ignite the ignition means.
The flame is propagated to the gas generating agent in the combustion chamber and the gas generating agent starts combustion, and the internal pressure of the combustion chamber rises with this combustion. The hot combustion gas and combustion residues generated in the combustion chamber flow into the cooling collection chamber.

The combustion gas is efficiently cooled and the combustion residue is effectively collected by the cooling collection filter in the cooling collection chamber. The gas thus cooled and the combustion residue is collected is discharged from the cooling collection chamber into the airbag to expand and deploy the airbag.

[0024]

EXAMPLES The present invention will be described more specifically below with reference to Examples and Comparative Examples. (Example 1) Gas generator 1 described above with reference to Figs.
Of the cooling and collecting chamber 7 has an outer diameter of 101 mm, the combustion chamber 5 has an outer diameter of 75 mm, the ignition chamber 3 has an outer diameter of 25 mm, and the housing 2 is made of stainless steel and has a height of 40 mm and a thickness of 1 mm. Also,
The gas outlets 15 are provided as holes with a diameter of 8 mm at 24 locations on the circumference at equal intervals, and the second partition walls 6 are provided as holes at a diameter of 8 mm at 12 locations on the circumference at equal intervals. In the ignition chamber 5, 2 g of boron glass stone as an ignition agent 10 and an electric ignition type squib 8 are arranged.

In the cooling collection chamber 7, a cooling collection filter 17 is provided.
In this case, the structure shown in Table 1 below is integrally formed into a width of 37 mm by press molding. Since the cooling / collecting filter 17 is integrally formed, it can be easily housed in the cooling / collecting chamber 7. In the items of the middle layer in Table 1, the layer with the smaller number represents the inner circumference side, that is, the first layer represents the innermost circumference and the third layer represents the outermost layer.

In the combustion chamber 5, a mixture of 58% by weight of sodium azide (NaN ₃ ), 34% by weight of manganese dioxide (MnO ₂ ) and 8% by weight of bentonite (silicate mineral) as the gas generating agent 12 was used. 99.5 g of pellets formed to have a width of 6 mm and a thickness of 5 mm were used as the combustion chamber filter 13 with 45 g of stainless steel knit wire having a wire diameter of 0.36 mm in contact with the second communication hole 14 and having an outer diameter of 73 mm and an inner diameter of 59.
A press-formed product having a height of 20 mm and a height of 20 mm was used.

The gas generator 1 was attached to a tank tester of 60 liters, and the pressure inside the combustion chamber 5, the pressure inside the tank tester, and the amount of sodium discharged into the tank were measured.

As a result, the maximum pressure in the combustion chamber 5 is 95 kgf.
/ Cm ² low, tank internal pressure high 2.48 kgf / cm ² high, sodium content as low as 136 mg, gas generator 1
The performance of was very good.

[0029]

[Table 1]

(Embodiment 2) A similar test was conducted using the same construction as in Embodiment 1 except that the cooling and collecting filter 17 shown in Table 2 was used.

As a result, the maximum pressure in the combustion chamber 5 is 65 kgf.
/ Cm ² , the internal pressure of the tank was as high as 2.47 kgf / cm ² , and the sodium content was as low as 151 mg, and the performance of the gas generator was extremely good.

[0032]

[Table 2]

(Comparative Example 1) A similar test was conducted using the cooling trapping filter of Example 1 except that the cooling trapping filter shown in Table 3 was used.

As a result, the maximum pressure in the combustion chamber 5 is 50 kgf.
/ Cm ² and lower, although the tank internal pressure was up to 3.05 kgf / cm ^2, can not collect the residue and sodium for ceramic fiber paper is destroyed, sodium content was very high and 2100mg .

[0035]

[Table 3]

(Comparative Example 2) A similar test was carried out using the cooling trapping filter of Example 1 except that the cooling trapping filter shown in Table 4 and FIG. 4 was used. Figure 4
As shown in FIG. 3, the cooling and collecting filter includes a plain weave wire mesh 21, a sintered metal fiber nonwoven fabric 22, a ceramic fiber paper 2 from the inner peripheral side.
3, a sintered metal fiber non-woven fabric 24, a plain weave wire mesh 25, and a plain weave wire mesh 26.

As a result, the sintered metal fiber non-woven fabric 22 of the inner layer after combustion is partially broken near the second communication hole 14 due to insufficient strength, and the ceramic fiber paper 23 is clogged with residue sticking to it. Was there. The maximum pressure of the combustion chamber 5 is as high as 105 kgf / cm ² , and the tank internal pressure is 1.90 k at maximum.
The amount of sodium was as large as 650 mg at gf / cm ² .

[0038]

[Table 4]

As described above, in Examples 1 and 2, the pressure in the combustion chamber 5 is low, the gas ejection pressure is high, and the amount of sodium passing through the cooling and collecting filter 17 is small.
Therefore, the cooling and collecting filter 17 is not broken or clogged by the combustion residue generated when the gas generating agent 12 burns, and the metal sodium, sodium oxide and other combustion residues are effectively collected. be able to.

Further, a predetermined filtering effect can be obtained without using a large amount of metal mesh such as the sintered metal fiber nonwoven fabric 22 obtained by simultaneously sintering the plain woven metal mesh 21 and the flat tatami woven metal mesh 25. Furthermore, since the pressures inside the combustion chamber 5 and the cooling collection chamber 7 do not rise significantly, the housing 2 can be designed to be thin and the gas generator 1 can be made lightweight.

On the other hand, when a cooling collection chamber filter having a rough screen, a ceramic fiber paper and a flat woven wire mesh is used (Comparative Example 1), the pressure in the combustion chamber 5 and the ejection pressure are good, but The amount of sodium passing through the filter is extremely high. Further, in the case of using the cooling collection chamber filter in which the sintered metal fiber nonwoven fabrics 22 and 24 are arranged on both sides of the ceramic fiber paper 23 (Comparative Example 2), the ejection pressure is low and the combustion chamber 5
The internal pressure is considerably high, and more sodium passes through the filter.

In this case, since the tatami-woven wire mesh is not arranged inside the sintered metal fiber nonwoven fabric 22 located in the inner layer, the sintered metal fiber nonwoven fabric 22 is partially broken and the combustion residue is hardly collected. It is a thing. Further, since the sintered metal fiber nonwoven fabric 22 on the inner layer side was partially broken, a large amount of combustion residue adhered to the ceramic fiber paper 23 to cause clogging, and the pressure in the combustion chamber 5 increased. Moreover, the sintered metal fiber non-woven fabric 24 on the outer layer side is used to reinforce the ceramic fiber paper 23, but since the effect of cooling the combustion gas is high, the gas becomes supercooled and the tank internal pressure is 2.0 k.
It was a low value below gf / cm ² .

The present invention is not limited to the embodiments, but may be embodied by arbitrarily changing the configuration as follows, for example, within the scope not departing from the spirit of the invention. (1) The thickness of the knit wire molded products 18, 20 is appropriately adjusted so that the inner side is thicker or the outer side is thicker, and the cooling and collecting efficiency is increased. (2) The thickness of the ceramic fiber paper 19 is changed according to the thickness of the knit wire molded products 18, 20. (3) The knit wire molded products 18 and 20 and the ceramic fiber paper 19 are separately molded and laminated.

[0044]

As described in detail above, the cooling and collecting filter and the gas generator of the present invention have the following excellent effects.

That is, the combustion gas generated by the combustion of the gas generating agent can be effectively cooled, and
It is possible to reliably collect the combustion products without causing clogging. Further, the manufacturing is easy and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a gas generator of the present invention.

FIG. 2 is a perspective view showing an embodiment of a cooling collection filter.

FIG. 3 is a partial vertical cross-sectional view showing an embodiment of a cooling collection filter.

FIG. 4 is a partial vertical cross-sectional view showing a comparative example of a cooling collection filter.

[Explanation of Codes] 1 ... Gas Generator, 3 ... Ignition Chamber, 5 ... Combustion Chamber, 7 ... Cooling Collection Chamber, 17 ... Cooling Collection Filter, 18 ... Inner Knit Wire Molded Product, 19 ... Ceramic Fiber Paper, 20 … Outer side knit wire molding.

Claims (2)

[Claims] 1. A cooling and collecting filter for cooling a gas and collecting a solid residue in the gas, which is formed by laminating a knit wire molded product, a ceramic fiber paper, and a knit wire molded product in this order. A cooling collection filter characterized by being provided. 2. An ignition chamber provided with an ignition means, a combustion chamber provided with a gas generating agent burned by the ignition means, a combustion gas generated by combustion of the gas generating agent is cooled, and a combustion product is captured. A gas generator comprising a cooling and collecting chamber having a cooling and collecting filter for collecting, wherein the cooling and collecting filter is formed by sequentially laminating a knit wire molded product, ceramic fiber paper, and a knit wire molded product. A gas generator characterized by being used.