JPH04118336A - Gas generator - Google Patents

Abstract

PURPOSE:To effectively scavenge combustion products without emerging clogging with them, and moderately cool gas by using substance made of specified material as a combustor filter, and setting the weight of the combustor filter at specified ratio against the total weight of a gas producing agent. CONSTITUTION:An ignition chamber 1 is provided at the central part of a housing 19. And an annular combustor 4 is provided concentrically at the outer peripheral part of the ignition chamber 1, and a gas producing agent 6 is contained and also a combustor filter 7 is provided inside the combustor 4. Further, an annular refrigeration collecting chamber 8 is formed concentrically against the ignition chamber 1 at the outer peripheral part of the combustor 4. In the above gas generator, the combustor filter 7 is formed with 8-100 mesh metallic screens that do not react with the combustion products of the gas producing agent 6 having a melting point of not less than the combustion temperature of the gas producing agent 6. And the total weight of the combustor filter 7 is set at 20-80weight% against the total weight of the gas producing agent 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas generator, and more particularly to a gas generator for an airbag for protecting an automobile occupant.

[Conventional technology]

As shown in FIG. 7, in a conventional gas generator, a plurality of coarse metal mesh screens 33 are tightly attached to the wall side of the combustion chamber 31 as a combustion chamber filter 32 in the combustion chamber 31 of the gas generator 30. The gas generating agent 36 is installed by installing a glass fiber cloth 34 on the inside thereof, and further providing a fine metal mesh screen 35 on the inside of the glass fiber cloth 34, that is, on the side in contact with the gas generating agent. A gas generator 30 is known that collects combustion products such as sodium oxide and particulate combustion residue (Japanese Patent Laid-Open No. 110642/1983).

[Problem to be solved by the invention]

However, although the conventional gas generator 3o uses the glass fiber cloth 34 and therefore has a high effect of collecting granular solid residue, the glass fibers constituting the cloth melt at the combustion temperature of the gas generating agent 36. As the adhesive glass fibers and the combustion products of the gas generating agent come together and cause clogging, the metal mesh screen 33 near the wall of the combustion chamber 4 may become sticky. Sometimes sticky glass fibers would stick to them, causing them to become clogged. As a result, the internal pressure of the combustion chamber 31 increases significantly, the combustion chamber 31 and the cooling collection chamber 37 are deformed, and the scum is discharged unfiltered even though it passes through the cooling filter 39. This is partly due to the so-called short-pass phenomenon. There was a problem with it happening.

Further, the metal mesh screen 33.35 is attached to the combustion chamber 3.
A coarse metal mesh screen 33 is placed on the side of the communication hole 38 of No. 1, and a fine metal mesh screen 35 is placed on the side in contact with the gas generating agent. Since even the metal mesh screen 35 on the side of the gas generating agent 36 is filtered at once, there is a problem that clogging is likely to occur.

An object of the present invention is to provide a gas generator using a combustion chamber filter that effectively collects combustion products without causing clogging when a gas generating agent is combusted, and appropriately cools the residue. Our goal is to provide the following.

[Means to solve the problem]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems.

That is, the present invention provides a gas generator comprising an ignition chamber equipped with an ignition means, a combustion chamber equipped with a gas generating agent and a combustion chamber filter, and a cooling collection chamber equipped with a cooling filter. The filter does not chemically react with the combustion products of the gas generating agent, and has a melting point of 8 to 80% above the combustion temperature of the gas generating agent.
The gist of the present invention is a gas generator characterized in that it has a metal screen of 100 meters and the total weight of the combustion chamber filter is 20 to 80% by weight of the total weight of the gas generating agent.

Hereinafter, the gas generator of the present invention will be explained based on FIGS. 1 to 6.

FIG. 1 is a longitudinal sectional view showing an example of a gas generator of the present invention. In FIG. 1, an ignition chamber 1 is arranged in the center of a housing 19 of the scum generator. A squib 2a is erected and fixed at the inner bottom of the ignition chamber 1, a beam wire 2b is connected to the squib 2a, and an ignition agent 3 is filled and coated around the upper part of the squib 2a, Together they form the ignition means.

An annular combustion chamber 4 is arranged concentrically on the outer periphery of the ignition chamber 1, and an ignition chamber communication hole 5 is provided in the partition wall between the ignition chamber 1 and the combustion chamber 4. It communicates with the combustion chamber 4. Additionally, a gas generating agent 6 is provided inside this combustion chamber 4.
is housed therein, and a combustion chamber filter 7, which will be described later, is also provided.

Furthermore, an annular cooling collection chamber 8 is formed on the outer periphery of the combustion chamber 4 concentrically with respect to the ignition chamber l, and a partition wall between the combustion chamber 4 and the cooling collection chamber 8 is provided with a combustion chamber 8. A chamber communication hole 9 is provided through the combustion chamber 4 and the cooling collection chamber 8 to communicate with each other, and a gas discharge hole 10 is also provided through the outer wall of the cooling collection chamber 8 to communicate the combustion chamber 4 with the cooling collection chamber 8. and communicates with the outside of the gas generator.

A cooling filter 11 is disposed inside the cooling collection chamber 8 so as to cover the gas discharge hole 10 .

FIG. 2 and FIGS. 4 to 6 are sectional views showing examples of combustion chamber filters used in the gas generator of the present invention, respectively. Moreover, FIG. 3 is a perspective view showing an example of a combustion chamber filter used in the scum generator of the present invention.

The combustion chamber filter may be made of any metal as long as it does not chemically react with the combustion products of the gas generating agent 6 and has a melting point higher than the combustion temperature of the scum generating agent 6, such as stainless steel, It is selected from metals such as iron, nickel, aluminum, and alloys thereof, and stainless steel is the most preferred among them. On the other hand, nonmetallic substances such as glass fibers, which begin to melt at the combustion temperature of the gas generating agent 6 (1000 to 1400°C) and become sticky, are not used. Furthermore, metals such as lead whose melting point is lower than the combustion temperature of the gas generating agent 6 are not used even if they are metallic substances. Furthermore, the gas generating agent 6 is generally composed of sodium azide and an oxidizing agent, but the gas generating agent 6 is also made of aluminum silicate or the like, which has chemical reactivity with sodium oxide, which is a combustion product. Compounds are also inappropriate as materials for the combustion chamber filter 7.

The metal mesh screen of the combustion chamber filter 7 is selected from metal mesh screens having a particle size of 8 to 100 mesh. When the combustion chamber filter 7 is composed of one type of mesh as shown in FIG.
Preferably, a mesh metal mesh screen 12 is used. On the other hand, the metal mesh screen 18 to 5 shown in FIG.
A press-molded product 13 of knit wire with a mesh size of 0 may be used.

In addition, the combustion chamber filter 7 has two types of mesh, that is, as shown in FIG. 5, the gas generating agent 6 side (the right side of the figure) is rough;
If the combustion chamber 4 wall side (left side in the figure) has a two-layer structure composed of fine mesh, one or two metal mesh screens 14 of 8 to 10 meshes are installed on the gas generating agent 6 side, and the combustion chamber 4 wall side is made of a fine mesh. It is preferable to use an appropriate amount of metal mesh screen 15 of 18 to 30 mesh on the side. Furthermore, the combustion chamber filter 7 has three types of mesh, that is, as shown in FIG.
In the case of a three-layer structure consisting of a fine mesh (on the left side of the figure), a metal mesh screen 14 of 8 to 10 meshes is placed on the scum generator 6 side, and then a metal mesh screen 14 of medium coarseness of 12 to 18 meshes is placed on the scum generator 6 side. Metal mesh screen 16 with 2.1 to 100 mesh on the combustion chamber 4 wall side
It is preferable to use an appropriate amount of 7.

Here, if the metal mesh screen has less than 8 meshes, the filtration performance is insufficient, and if it exceeds 100 meshes, clogging is likely to occur, which is not preferable.

Further, in the present invention, the combustion chamber filter 7 may be constructed by combining a knit wire press-molded product with a metal mesh screen, or a metal mesh screen having a three-layer structure or more, as appropriate.

Next, although the weight of the combustion chamber filter varies depending on its material, it is in the range of 20 to 80% by weight, preferably in the range of 40 to 60% by weight, of the total weight of the gas generating agent 6. If the weight is less than 20% by weight, the amount of filter is small and sufficient cooling and filtration effects cannot be obtained. If it exceeds 80% by weight, the cooling and filtration effects are generally sufficient, but the As a result, the total amount of gas discharged from the gas generator is reduced, resulting in insufficient inflation of the airbag.

Since the flow rate of gas is slower in the combustion chamber 4 than in the cooling collection chamber 8, the combustion chamber filter 7 exhibits a greater cooling effect than the cooling filter 11.

Also, if you want to obtain the same cooling and filtration effect for the above reasons,
If you increase the amount of combustion chamber filter used, cooling filter 1
The relationship is to reduce the usage of 1. For example, if the gas generating agent 6 is 90g, the combustion chamber filter 7 is 30g (
The amount of the cooling filter 11 used is about 110g (approximately 33% of the gas generating agent 6), and the amount of the combustion chamber filter 7 is 60g.
(approximately 67% of the gas generating agent 6)
The usage amount of 1 is about 80g.

The combustion chamber filter 7 preferably has a rectangular cross section or a shape close to it. When the cross section is rectangular, the filter as a whole has a shape as shown in FIG. 3.

The height of the combustion chamber filter 7 may be equal to the height of the combustion chamber 4, but is preferably 1.5 to 4 times the diameter of the combustion chamber communication hole 9; If is less than 1.5 times, there is a risk that the generated gas will pass from the combustion chamber 4 to the cooling collection chamber 8 without being cooled or filtered due to the insufficient height of the filter. Furthermore, if the height exceeds four times, even if a filter with the same thickness is produced, it will not only be heavier but also more expensive.

The combustion chamber filter 7 is arranged in the combustion chamber 4 so as to cover the combustion chamber communication hole 9, and so that the position of the combustion chamber communication hole 9 is approximately at the midpoint of the height of the combustion chamber filter 7. Ru.

[Effect]

In the gas generator of the present invention configured as described above,
For example, when a car equipped with a gas generator collides, the collision detection device turns on the power to the gas generator, ignites the ignition agent, and the flame propagates to the scum generator in the combustion chamber, causing the gas generator to burn. As combustion begins, the internal pressure of the combustion chamber increases. When the high-temperature combustion gas and combustion products generated in the combustion chamber pass through the combustion chamber filter, they are cooled appropriately without clogging the combustion chamber filter, and then pass through the combustion chamber communication hole to be cooled and captured. Flow into the collection room.

When passing through the cooling filter, the combustion gas is further cooled and uncollected combustion products are collected. In this way, the combustion products are efficiently and effectively collected, and the cooled gas is discharged from the gas outlet into the airbag to ensure that the airbag is inflated and deployed.

〔Example〕

The present invention will be specifically explained below with reference to Examples and Comparative Examples.

Example 1 Cooling collection chamber 8 has an outer diameter of 100 mm, combustion chamber 4 has an outer diameter of 75 m
m, ignition chamber l or outer diameter 25mm, height 40mm.

A gas generator as shown in Fig. 1 having a stainless steel housing with a thickness of 1 mm was used, and an ignition agent 3 was placed in the ignition chamber 1.
As a coating, 2 g of horon saltpeter was filled, and an electrically ignited scoop 72a and a riet wire 2b were attached.

In addition, in the cooling collection chamber 8, a hand-woven stainless steel metal screen with a height of 37 mm, a wire diameter of 0.30 mm, and 24 meshes is wound five times as a cooling filter 11, and 500 g of stainless steel fibers with a wire diameter of 40 μm are wrapped around the outside of the screen. A stainless steel fiber sintered filter with a height of 37 mm and a thickness of 0.8 mm was wound around once, and 375 g/m of ceramic fiber with a wire diameter of 2.8 μm was used on the outside of the filter, and the thickness was 2.5 mm. Wrap a ceramic fiber filter with a height of 37 mm once,
On the outside, the wire diameter is 0.18X0.14mm, 40X200
A mesh stainless steel metal screen with a tatami edge was wrapped once, and a linear 0.35 mm, 18 mesh hand-woven stainless steel metal screen was wound twice around the outside.

Additionally, on the top and bottom of the cooling filter 11, there are packings 1 made of graphite with a thickness of 1 mm to prevent gas leakage.
8 was installed.

The combustion chamber 4 contains sodium azide 6 as a gas generating agent 6.
0% by weight, manganese dioxide 30% by weight, bentonite (
It contains 90 g of a mixture of 10 wt. A plain weave stainless steel metal screen with a diameter of 0.30 mm and 18 mesh is wound around 8 times.
A total of 60 g (about 67% of the weight of the gas generating agent 6) was provided.

In addition, on the outer wall of the cooling collection chamber 8, there is a gas outlet lO.
24 holes with a diameter of 8 mm are provided at equal intervals, and 12 holes with a diameter of 8 mm are provided as combustion chamber communication holes 9 on the outer wall of the combustion chamber 4.
A gas generator as shown in Fig. 1 was created by providing 10 holes with a diameter of 2.5 mm at equal intervals as ignition chamber communication holes 5 on the outer wall of the ignition chamber 1. .

Attach a tank tester with a capacity of 601 to this gas generator,
As a result of measuring the pressure in the combustion chamber 4, the internal pressure of the tank tester, and the amount of metallic sodium in the combustion products discharged into the tank, the maximum pressure in the combustion chamber 4 was 81 kgf.
/cnf, the maximum tank internal pressure was 2.2 kgf/c, and the sodium output was 14 mg, which are extremely good values for an air pack gas generator. Note that the allowable value of the tank internal pressure is usually 1.6 to 3.0 kg/cm.

Example 2 In Example 1, a hand-woven stainless steel metal screen with a height of 20 mm, a wire diameter of 0.30 mm, and 24 meshes was wrapped around the outermost circumference five times as the combustion chamber filter 7, and then a 20 mm height, A hand-woven stainless steel metal screen with a wire diameter of 0.35 mm and 12 meshes is wound twice, and a hand-woven stainless steel metal screen with a height of 20 mm and a wire diameter of 0.8 mm and 8 meshes is placed on the inside of the screen in contact with the gas generating agent 6. The same test as in Example 1 was conducted using the same scum generator as in Example 1, except that the same scum generator as in Example 1 was used, with a total of 50 g (approximately 56% of the weight of gas generating agent 6) being wound around once. .

As a result, the maximum pressure in the combustion chamber 4 is 65 kgf/cur,
Tank internal pressure is maximum 2. 1 k g f ,/crTr
Similarly to Example 1, the excreted sodium amount was 17 mg, which was an extremely good value.

Comparative Example 1 As the combustion chamber filter 7, a hand-woven stainless steel metal screen with a height of 38 mm, a wire diameter of 0.35 mm, and 18 meshes was wound around the outermost circumference once, and 330 g of glass fiber with a wire diameter of 9 mm was used inside the screen. Height 37mm with thickness 3mm
A glass fiber filter of 37 mm in height and 0°2 mm in wire diameter is placed on the inside of the filter on the side in contact with the gas generating agent 6.
The same test as in Example 1 was conducted using the same gas generator as in Example 1 except that a hand-woven stainless steel metal screen with 0 mesh was wound twice.

As a result, the internal pressure of the combustion chamber 4 reaches a maximum of 160 kgf/cr.
l and the combustion chamber filter 7 become clogged and the internal pressure rises significantly, and also because the amount of combustion chamber filter 7 is small,
Due to insufficient cooling and filtration, the tank internal pressure reached a maximum of 3.3 kgf.
/cmf. Additionally, as the internal pressure of the combustion chamber 4 has increased significantly, the combustion chamber 4 and the cooling collection chamber 8 are deformed, resulting in a phenomenon called short pass, in which scum and combustion products exit unfiltered without passing through the cooling filter 11. This occurred in some cases, and the amount of sodium excreted was as high as 330 mg.

Comparative Example 2 In Example 1, the combustion chamber filter 7 had a wire diameter of 1 m.
The same test as in Example 1 was conducted using the same gas generator as in Example 1, except that a 5-mesh hand-woven stainless steel metal screen was wound five times to give a weight of 60 g.

As a result, the maximum pressure in the combustion chamber 4 was 90 kgf/crl, which was slightly higher than in Example 1, or the cooling and filtration in the combustion chamber 4 was insufficient, causing clogging in the cooling collection chamber 8. The tank internal pressure was extremely high with a maximum of 4.5 kgf/ci and sodium discharge of 420 mg.

Comparative Example 3 In Example 1, the combustion chamber filter 7 had a wire diameter of 0.2
The same test as in Example 1 was conducted using the same gas generator as in Example 1, except that a plurality of hand-woven stainless steel metal screens of 150 mm were wound to weigh 60 g.

As a result, the maximum pressure in the combustion chamber 4 is 180 kgf/cm
As in Comparative Example 1, the combustion chamber 4 and the cooling collection chamber 8 were deformed, resulting in a short pass.

Comparative Example 4 A similar test was conducted using the same gas generator as in Example 1 except that the combustion chamber filter 7 was 10 g (approximately 11% of the weight of the gas generating agent 6).

As a result, the maximum pressure in the combustion chamber 4 was 98 kgf/ci, which was slightly higher than in Example 1, or the cooling and filtration in the combustion chamber 4 was insufficient, causing clogging in the cooling collection chamber 8, and the tank The internal pressure was as high as 4.2 kgf/crf and the sodium output was 180 mg.

Comparative Example 5 A similar test was conducted using the same gas generator as in Example 1, except that the combustion chamber filter 7 was 80 g (approximately 89% of the weight of the gas generating agent 6).

As a result, the maximum pressure in the combustion chamber 4 was 92 kgf/cr&, which was only slightly higher than in Example 1, and the tank internal pressure was as low as 1.2 kgf/cr& because it was cooled more than necessary.

In this way, in the scum generator of this embodiment, the glass fiber cloth 34, which becomes sticky under the high temperature and high pressure environment where the gas generating agent 6 burns, is not used as the combustion chamber filter 7.
A metal mesh screen that does not chemically react with the generated gas is used, and the particle size is 8 to 100 mesh.
Since the weight is 20 to 80% by weight of the total weight of the gas generating agent 6, the pressure in the combustion chamber does not increase significantly due to adhesive glass fibers adhering to the metal mesh screen.
Sufficient cooling and filtration effects can be obtained.

Also, the height of the combustion chamber filter 7 is set to 1.0 mm of the hole diameter of the combustion chamber communication hole 9. Since the height is set in the range of 5 to 4 times, and the position of the combustion chamber communication hole 9 is located approximately at the midpoint of the combustion chamber filter, the waste flow efficiently filters the combustion chamber filter 7. cooling and combustion product collection are effectively carried out.

In addition, in Example 2, the metal mesh screen is arranged so that the mesh on the gas generating agent 6 side is coarse, and the mesh on the combustion chamber 4 wall side is finer than that, so that coarse combustion products are In order, as you go to the outside of the combustion chamber filter,
Since fine particles are collected and the combustion chamber filter 7 is less likely to be clogged, the pressure in the combustion chamber 4 does not increase significantly and efficient filtration can be performed. Furthermore, the wall thickness of the housing 19 can be designed to be thin, and weight and cost reductions can be achieved.

〔Effect of the invention〕

The gas generator of the present invention effectively removes the combustion products when the gas generating agent is combusted, without causing clogging by the combustion products or the filter itself, and without significantly increasing the pressure in the combustion chamber. Moreover, it is possible to efficiently collect the gas and at the same time, it is possible to cool the gas appropriately.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a gas generator showing an example of the present invention, and FIGS. 2, 4, 5, and 6 show examples of combustion chamber filters used in the gas generator of the present invention. Longitudinal sectional view, 3rd
The figure is a perspective view showing one embodiment of the combustion chamber filter used in the gas generator of the present invention, and FIG. 7 is a sectional view showing a conventional scum generator. DESCRIPTION OF SYMBOLS 1... Ignition chamber, 2a... Squib as ignition means, 2b... Lead wire as ignition means, 3... Ignition agent as ignition means, 4... Combustion chamber, 6... Gas generating agent, 7... Combustion chamber filter, Meter... Cooling collection chamber, 1
1... Cooling filter.

Claims (1)

[Claims] 1. Ignition chamber (1) equipped with ignition means (2a, 2b, 3)
and a combustion chamber (4) equipped with a gas generating agent (6) and a combustion chamber filter (7), and a cooling collection chamber (8) equipped with a cooling filter (11), The combustion chamber filter (7) is a metal screen of 8 to 100 mesh that does not chemically react with the combustion products of the gas generating agent (6) and has a melting point higher than the combustion temperature of the gas generating agent (6). A gas generator characterized in that the total weight of the combustion chamber filter (7) is 20 to 80% by weight of the total weight of the gas generating agent (6).