JPH042542A - Airbag gas generator filter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is used in an automobile airbag device that inflates and deploys an air hang for protecting the human body to absorb the impact on the driver and passengers in the event of a collision of an automobile or the like. This invention relates to filters for gas generators.

[Conventional technology and its issues]

Automotive airbag devices include a pressure detection device at the time of a collision,
It consists of a gas generator for inflating the bag and a bag, and has recently been attracting attention as a device that absorbs shocks applied to drivers and passengers in the event of a collision.

By the way, a gas generator ignites and burns a gas generating agent (for example, a mixture of soda azide and copper oxide) and guides the generated gas into a bag through a filter. There are important roles such as

First, it has the role of capturing harmful components other than gas generated by combustion of the gas generating agent and preventing them from entering the bag.

In other words, after the bag is inflated, it needs to be gradually deflated for shock absorption and escape.The bag is provided with a gas escape hole, and when harmful gas is introduced into the hang, it will exit through this hole and enter the human body. Because it causes harm. For example, when sodium azide is used as a gas generating agent, harmful components such as sodium metal and sodium oxide are generated according to the following reaction formula.

2 NaN3 + CuO → 3 Nz + Cu + NazO Secondly, it has the role of controlling the rate of expansion of the hang by controlling the rate of gas release from the combustion chamber of the gas generator.

That is, the speed at which the hang expands is determined by the combustion rate of the gas generating agent and the gas flow characteristics from the filter. The combustion rate of the gas generating agent is determined by the type, composition, and amount of the gas generating agent, as well as the pressure during combustion, and the pressure inside the combustion chamber is determined not only by the amount of reacted gas generating agent but also by the flow of gas through the filter. is also affected. In this way, the reaction rate of the gas generating agent and the flow resistance of the filter interact with each other and determine the gas flow characteristics into the bag. Therefore, precise control of the flow characteristics of the filter is essential to achieving the proper inflation rate of the bag.

BACKGROUND ART Conventionally, filters for airbag gas generators have been made by laminating wire mesh or metal fibers with different mesh sizes.

However, in order to satisfy the gas flow characteristics required for air hang generators, materials made of wire mesh or laminated metal fibers have to have mesh openings and porosity that are required to satisfy the trapping characteristics of harmful components. It is necessary to take a larger value than the actual value.

Therefore, in the past, even if the gas flow characteristics were satisfied,
There is a problem in that the trapping properties of harmful components are not necessarily satisfactory.

Additionally, airbag gas generator filters have traditionally been
- Although it is often formed into a ring shape for boat fishing, it is time-consuming to layer multiple layers of wire mesh to form a ring shape, and the wire mesh tends to fray at the formed end.
Another problem was that it was difficult to assemble.

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a filter for an air bang gas generator that can appropriately control flow characteristics and has good trapping characteristics for harmful components.

[Means to solve the problem]

In order to solve the above problems, this invention attempts to use a three-dimensional network structure porous body with controlled pore diameter and gas flow resistance by compression molding as a filter for an airbag gas generator. It is something to do.

FIG. 1 shows the structure of a three-dimensional network porous body to be used as a filter in the present invention.

A porous material with a three-dimensional rod-like structure is a porous material consisting of a connected skeleton and pocket-like spaces, and because of its high porosity, the gas flow resistance is extremely small, but the gas is trapped in the irregular pores. The particles are difficult to detach from the pores, so the solid matter collection performance is superior to wire mesh or metal fiber molded bodies.

Such a three-dimensional network structure porous material, for example,
As shown in Japanese Patent Publication No. 7-39317 and Japanese Patent Publication No. 57-5877, it can be manufactured by subjecting a foamed resin having continuous holes to conductive treatment and then electroplating it.

Therefore, the three-dimensional network structure porous body produced by such a manufacturing method has limitations in mesh size and porosity.

In other words, the opening is limited by the opening of the foamed resin used and the throwing power during electroplating, and is usually 3001.
It is difficult to obtain the following: Also, the pressure loss value is 5■
Thick wall, under atmospheric pressure and wind speed of 3 m/see, usually 20 H.
It is extremely small, less than 0.

On the other hand, in airbag gas generators, soda azide (
When a gas generating agent containing NaN3) is combusted, about 30 to 50 g of harmful particles mainly composed of sodium oxide and having a particle size of about 0.5 to 10 - are generated. Considering the safety of the human body, it is desirable to trap these harmful particles as much as possible with a filter, but it is necessary to suppress the amount of outflow from the gas generator to 1 g or less at the maximum. For this purpose 1
It is necessary to almost completely trap more than - harmful particles.

Furthermore, the appropriate pressure drop value required for a filter varies depending on the part of the near bag used (whether it is for the driver or a passenger) and the structure of the air hang. That is, the airbag for the driver is usually set in the center of the driver's steering wheel, and the air hang needs to be deployed in the space between the steering wheel and the driver. On the other hand, the passenger air hang is usually located at the bottom of the dash board, and the airbag gas generator filter needs to be deployed in a wider space from the bottom of the dash board to the passenger. Furthermore, there are various structures of gas generators, particularly the paths through which the generated gas is guided to the bag through the filter. In either case, the ultimate requirement is that the rate of gas supply to the hang falls within a reasonable range.

FIG. 3 is an example of the required characteristics of the gas supply rate to the bag of the air bag gas generator, that is, the gas discharge rate from the gas discharge hole. Of course, the required characteristics of gas discharge speed are not constant, as they vary depending on the type and amount of gas generator used, the size of the bag, the size of the car, the material of the bag, etc.
In order to satisfy this gas discharge rate, the pressure drop value of a filter made of a porous three-dimensional network structure must be 200 to 200 at a flow rate of 1rrf/lll1n under atmospheric pressure for use by drivers.
A range of 2000 mmH2O is suitable for a fellow passenger, and a range of 20 to 200 IIwH20 under the same conditions is appropriate.

In order to satisfy the above conditions, we investigated the particle collection performance and gas flow characteristics in detail using a three-dimensional network porous molded body, and found that the maximum aperture on the gas inlet side was the largest aperture on the gas outlet side. It has been found that a porous material with a three-dimensional rod-like structure, which has a pore size distribution that is more than twice the size of the opening, and whose flow characteristics are adjusted by compression molding, is suitable as a filter for airbag gas generators.

Furthermore, as a filter for airbag gas generators for drivers, the maximum aperture on the gas outlet side is 3 to 10 haze, and the pressure loss value is 200 to 2000 at atmospheric pressure and flow rate of 1 Bo/+win.
The three-dimensional network structure porous material is adjusted to the range of mHz O, and as a filter for a passenger airbag gas generator, the maximum aperture on the gas outlet side is 3 to 1 Om, and the pressure drop value is below atmospheric pressure. Flow rate 1m/! +Iin 200~200
It has been found that a three-dimensional network structure porous material adjusted to a range of 0 am Hz O is suitable.

Here, the maximum opening is a value calculated from the valve point pressure according to JIS B-8356.

As mentioned above, the reason why the maximum opening on the gas inlet side is made to be more than twice the maximum opening on the gas outlet side is as follows. That is, the filter gradually becomes clogged due to the collection of particles, resulting in an increase in pressure loss and a gradual slowing of the gas flow rate. If bag deployment is to be completed within a reasonable amount of time, filters must be designed with blinding in mind. Therefore, particles are generally more likely to pass through the filter at an early stage when the filter is not clogged. If the maximum aperture on the gas inflow side is more than twice the maximum aperture on the gas outlet side, relatively large particles will be collected at the large aperture on the inflow side, and small particles will be collected at the small aperture on the outlet side. Since it is made thinner, changes in gas flow velocity can be reduced. It has been confirmed through experiments that a generator filter for an airbag gas generator is effective when the capacity is at least twice as large.

Considering that the filters of gas generators for airbags are generally cylindrical, the specific method of compression molding is as follows:
You can choose from pultrusion, hydrostatic forming, and swaging.

In addition, creating a difference in the maximum opening can be achieved by using three-dimensional network porous bodies with different pore diameters before molding, or by varying the degree of compression.

In this invention, the material for the three-dimensional network porous body used is nickel, a nickel-chromium alloy made of nickel, and a nickel-chromium iron alloy from the viewpoint of strength and heat resistance.

Further, it is desirable that the thickness of the skeleton of the three-dimensional network porous material used be controlled as necessary to ensure strength.

〔Example〕

FIG. 2 shows an example of a gas generator for a driver.

This gas generator has a disk-shaped casing 1 with a
The ignition agent 2 and the ignition plug 3 are accommodated, and a gas generating agent 4 is accommodated in a gas generating agent storage chamber provided outside of the ignition agent 2 and the ignition plug 3.
The combustion gas flows out from a gas outlet 5 formed on the outer peripheral side wall of the casing 1.
A ring-shaped filter 6 that covers the gas outlet 5 is installed inside the outer peripheral side wall of the gas outlet 5.

In the gas generator shown in Fig. 2 above, the gas generating agent 4 is a mixture of sodium azide (NaNx) and copper oxide (Cub) made into pellets with a diameter of 3 cm and a height of 2.5 m in a total amount of 95 g. Combustion experiments were conducted using various types of filters 6. The characteristics of the various filters 6 are shown in Table 1, and FIG. 4 shows the measurement results of the gas discharge rate.

The filters 6 used in this experiment are made of a three-dimensional network structure porous body made of nickel-chromium (trade name Selmesoto, manufactured by Sumitomo Electric), and each has an outer diameter of 125 mm.
ga, and the height is 21m+. Further, the thicknesses are as shown in Table 1.

Table 1 Next, FIG. 5 shows an example of a gas generator for a fellow passenger.

This gas generator has a structure in which an ignition agent 12 and an ignition plug 13 are housed in the axis of a cylindrical casing 11, and a gas generating agent 14 and a filter 16 are sequentially wound around the outside of the ignition agent 12 and an ignition plug 13. The outlet 15 is provided along the axial direction of the casing 11.

In the gas generator shown in FIG. 5 above, as a gas generating agent,
Combustion experiments were conducted using a total of 250 g of a mixture of sodium azide and copper oxide, and using various filters 16 with an outer diameter of 60 m shown in Table 2. The various characteristics are as shown in Table 2, and the measurement results of the gas discharge rate are shown.

FIG. 6 shows [Effects of the Invention] As described above, according to the present invention, as a filter for a gas generator for an air bag, the flow characteristics can be appropriately controlled, and the filter has good trapping characteristics for harmful components. You can get something.

In addition, the three-dimensional wire-like porous body does not have its end faces frayed like wire mesh, so it has the advantage of being easy to mold and easy to assemble.

[Brief explanation of drawings]

Figure 1 is an enlarged view of a three-dimensional network structure porous body, Figures 2 and 5 are cross-sectional views each showing an example of an airbag gas generator, and Figure 3 is an enlarged view of the airbag gas generator. There are graphs showing the gas supply rate, and Figures 4 and 6 are graphs showing the gas discharge rate, respectively. 1.11...Casing, 2.12...Ignition agent, 3.13...Ignition plug, 4.14...Gas generating agent, 5. 15...Gas outlet, 6.16...Filter patent applicant Sumitomo Electric Industries, Ltd.

Claims (3)

[Claims] (1) It is made of a three-dimensional network structure porous material with a pore size distribution such that the maximum opening on the gas inlet side is more than twice the maximum opening on the gas outlet side, and the flow characteristics are adjusted by compression molding. Features a filter for airbag gas generators. (2) The maximum opening on the gas outlet side is 3 to 10 μm, and the pressure loss value is 200 to 200 at a flow rate of 1 m^3/min under atmospheric pressure.
The filter for an airbag gas generator according to claim 1, characterized in that it is made of a three-dimensional network structure porous body compression-molded to have a porous material in the range of 0 mmH_2O. (3) The maximum opening on the gas outlet side is 3 to 10 μm, and the pressure drop value is 20 to 200 m at atmospheric pressure and a flow rate of 1 m^3/min.
The filter for an airbag gas generator according to claim 1, characterized in that it is made of a three-dimensional network structure porous body compression-molded so as to have a mH_2O range.