JP2003146182A - Gas generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid type gas generator capable of heating and releasing gas from a high pressure gas bomb as well as simultaneously satisfying miniaturization and simplification of a structure. SOLUTION: This gas generator is constituted by furnishing the bomb 1 loaded with high pressure gas, a cup type housing 4 with a donut type igniter 2 and an ignition means 3 stored in it, a rupture disc 6 to hold and seal pressure of the bomb 1 and an outer cylinder material 5 to connect and hold the bomb 1 and the housing 4 to each other so as to form a gas residing space 16 between the bomb 1 and the housing 4, and it constitutes its characteristic feature of releasing the gas from a gas releasing hole 17 provided on the outer cylinder material 5 by heating the gas heat-insulated, expanded and blown out from the bomb 1 by high temperature gas from the ignition means 3 and passing it through a filter material 10 provided along an inwall of the outer cylinder material 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generator used in an automobile air bag system.

[0002]

2. Description of the Related Art An air bag is known as one of safety devices for protecting an occupant from an impact generated when a vehicle crashes. This airbag operates with a large amount of high-temperature, high-pressure gas generated by a gas generator. Conventionally,
There are roughly two types of known methods for generating gas with this gas generator. One is a pyro system in which all the generated gas is generated by burning a solid gas generating agent. The other is a hybrid system in which a large amount of high-temperature and high-pressure gas is released by a cylinder holding a high-pressure gas and a small amount of explosive composition for supplying heat to the high-pressure gas in the cylinder.

In recent years, miniaturization can be mentioned as a performance required for a gas generator. The former pyro system is
In order to reduce the size of the gas generator, it is necessary for the gas generating agent in the gas generator to increase the number of moles of gas generated by combustion. As a gas generating composition for increasing the number of moles of gas generated by the gas generating agent, a gas generating composition containing guanidine nitrate as a fuel and ammonium nitrate as an oxidizing agent is effective in the composition.
For example, as in JP-A No. 11-292678, a gas generating composition containing a guanidine derivative as a nitrogen-containing organic compound, a phase-stabilized ammonium nitrate as an oxidizing agent, a pressure index adjusting agent, and a silicon compound as a detonation suppressing agent. Is disclosed. However, since the guanidine derivative and ammonium nitrate are contained in a large amount, the combustion speed is very slow, and in order to obtain sufficient combustion performance in the gas generator, it was necessary to burn the gas generating agent under higher pressure. In addition, since the internal pressure during operation of the gas generator is increased, the gas generator needs to have higher strength, resulting in an increase in size.

Further, in the case of a gas generant composition containing a guanidine derivative or a raw material having low reactivity such as ammonium nitrate as a composition, not only the slow burning rate but also the low ignitability of the gas generant is one of the problems. Is. The airbag has a time of about 30 to 60 ms from the start of operation to the deployment of the airbag, and even if the operation delay of the gas generator is small, the effect thereof is large and sufficient performance cannot be exhibited. When the ignitability of the gas generating agent is low, even if the igniter in the gas generator ignites, the time required for igniting the gas generating agent becomes long, resulting in a delay in ignition of the gas generator. Although the ignition delay can be improved to some extent by increasing the amount of transfer charge in the gas generator, the total amount of heat generated by the gas generator itself increases due to the increase in the amount of ignition charge, which results in cooling / cooling. The weight of the filter member is increased and the gas generator is larger.

[0005]

On the other hand, the hybrid type is suitable for miniaturization because it requires a small amount of gas generating agent. However, since it is necessary to hold the gas in the cylinder under high pressure, it is generally used as a gas generator.
High-pressure gas may escape from the cylinder within the service life of 5 years, and sufficient performance may not be exhibited. For this reason, it is necessary to seal the gas in the cylinder for a long period of time, and therefore it is necessary to seal the cylinder with a rupture disc having high mechanical fracture strength and high sealing property. As this type of gas generator, for example, Japanese Patent Application Laid-Open No. 8-2531
There is one disclosed in Japanese Patent Publication No. 00. This gas generator is
A rupturable diaphragm (rupture disc) with high rupture strength is used to enhance the gas tightness of the first container (cylinder) in which high-pressure gas is sealed, and the rupturable diaphragm is used as a second container equipped with a combustion chamber or the like. The hollow piston provided in the first container is pushed forward by the ignition of the propelling charge (ignition means) to surely rupture the rupturable diaphragm of the first container,
The high-pressure gas in the first container is surely released. As described above, the rupturable diaphragm can be reliably destroyed, but it is necessary to install a hollow piston or the like, which causes a problem that the structure of the gas generator becomes complicated.

Further, the destruction of the rupture disc for reliably sealing the cylinder is not broken by using a hollow piston or the like as disclosed in JP-A-8-253100, but the amount of transfer charge is increased. Others increase the pressure in the combustion chamber including the ignition means to destroy it. However, in order to increase the amount of the transfer charge, a room for storing the transfer charge is required, which makes it difficult to downsize the gas generator. Further, in this case, it is difficult to destroy the rupture disk at the same time as the ignition of the ignition means.

Further, in this type of gas generator, the high-pressure gas in the cylinder is adiabatically expanded and ejected from the cylinder, so it is necessary to heat and release the gas. There was also a problem that the gas from the room could not be heated sufficiently.

An object of the present invention is to provide a gas generator of a hybrid system capable of simultaneously satisfying the miniaturization and simplification of the structure and heating and discharging the gas from the high pressure gas cylinder.

[0009]

A gas generator according to claim 1 of the present invention for solving the above-mentioned problems contains a cylinder filled with high-pressure gas, a doughnut-shaped transfer charge and an ignition means. Cup-shaped housing, a rupture disk for holding and sealing the pressure of the cylinder, and an outer cylinder for connecting and holding the cylinder and the housing so as to form a gas retention space between the cylinder and the housing. And a filter provided along the inner wall of the outer cylinder member, in which the gas adiabatically expanded and ejected from the cylinder is heated by the high-temperature gas from the ignition means in the gas retention space. It is characterized in that the material is passed and gas is discharged from a gas discharge hole provided in the outer cylinder material. According to the above configuration, in the gas retention space formed between the cylinder and the housing, the adiabatic expansion gas ejected from the cylinder and the high temperature gas from the igniter provided in the housing are mixed and ejected from the cylinder. The incoming adiabatic expansion gas is efficiently heated and released from the gas release holes.

The gas generator according to a second aspect is the gas generator according to the first aspect, wherein the rupture disk is broken by the flame force from the ignition means. According to the above configuration, the structure of the gas generator can be simplified and the size can be reduced. Further, the adiabatic expansion gas ejected from the cylinder can be heated more efficiently.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of a gas generator according to the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic sectional view of an example of an embodiment of a gas generator according to the present invention. In FIG. 1, a gas generator P1 includes a cylinder 1 in which high-pressure gas is stored, a cup-shaped housing 4 in which a transfer charge 2 and an ignition means 3 are stored,
An outer cylinder member 5 for connecting and holding the cylinder 1 and the housing 4,
Filter material 1 provided along the inner circumference of the outer tubular member 5
It consists of zero.

The cylinder 1 is made of a metal such as stainless steel or aluminum, has a bottomed cylindrical shape, and the opening side is reduced in diameter in two steps. Argon or helium gas in the cylinder 1 is in sufficient quantity to inflate and actuate the airbag or the like (for example, 0.8 to 1.2 mol for the air curtain).
Loaded, pressure 20 MPa or more, preferably 25
The pressure is maintained above MPa, and the opening on one end side is sealed by a cylinder cap 23 having a rupture disk 6.

The thickness of the rupture disk 6 is not particularly limited as long as it can be broken by the ignition means 3. As a preferable thickness of the rupture disc 6,
0.05-0.5 mm, more preferably 0.1-0.
It is 3 mm.

The housing 4 is cup-shaped and comprises a bottom portion 7 and a side tubular portion 8. In the housing 4, the bottom portion 7 is formed thicker than the side tubular portion 8, and the stepped portion 11 is formed on the outer peripheral portion thereof. Further, a flame discharge port 13 that opens from the inside of the combustion chamber 12 to the outside is formed. The flame outlet 13 is reduced in diameter from the combustion chamber 12 to the outside. As a result, the flame power can be increased and the emitted flame can be concentrated on the central portion of the rupture disc 6. Although not shown, a metal sealing tape made of aluminum or the like is attached to the bottom 7 side of the flame outlet 13. This seal tape prevents moisture and the like from entering the combustion chamber 12,
This is to prevent the transfer charge 2 contained in 2 from getting damp. Further, this seal tape has a thickness of 100 μm or less, and is instantly melted by the flame caused by the ignition of the ignition means 3 and does not hinder the progress of the flame.

As shown in FIG. 1, inside the housing 4,
A doughnut-shaped (hollow columnar) transfer charge 2, a first cushion material 14, a second cushion material 15, and a holder 20 to which the ignition means 3 is caulked and fixed are sequentially loaded. These are fixed by bending the open end 21 of the housing 4 inward and pressing the holder 20. A space at the center of the housing 4 formed by the doughnut-shaped transfer charge 2 and the cushion members 14 and 15 forms a combustion chamber 12. First and second cushion materials 14, 1
Reference numeral 5 is made of ceramic fiber, silicon foam or the like, and is formed in a donut shape like the transfer charge 2.
The cushion materials 14 and 15 absorb the vibration transmitted to the transfer charge 2 so that the transfer charge 2 is not crushed by vibration or the like. This doughnut-shaped transfer charge 2 may be formed by stacking one or two or more transfer charges formed in a donut shape, or a granular transfer charge having a smaller diameter may be arranged in a donut shape via a support member. Good.

The ignition means 3 is arranged coaxially with the housing 4 and has a structure facing the flame outlet 13 formed in the bottom portion 7. Therefore, the flame from the ignition means 3 is discharged from the flame discharge port 13 without being blocked by the obstacle in the combustion chamber 12. The ignition means 3 is, for example,
An embolus 28 made of a resin such as polybutylene terephthalate, polyethylene terephthalate, nylon 6, nylon 66, polyphenylene sulfide, polyphenylene oxide, etc., containing glass fiber or the like is fixed to the metal holder 20 by caulking.

The ignition means 3 has an internal pressure rise of 4.7 MPa within 3 msec when ignited in a 10 cc tank.
A or more is preferable. As a result, the rupture disc 6 can be reliably broken by the flame force.

In order to generate such a flame force, an ignition hand
Zirconium is used as the ignition agent loaded in the stage 3.
(Zr), tungsten (W), potassium perchlorate (K
ClO _Four) As a component and fluororubber as a binder
It is preferable to use those that use
Good In addition, zirconium, tungsten, perchloric acid
The composition ratio (weight ratio) of arium is determined by the ignition line 3 of the bridge line.
It is decided to ignite enough by heat, for example,
Zr: W: KClO_Four= 3: 3.5: 3.5. Well
Also, the ignition powder has a large contact (contact area) with the bridge line.
Then, when the tube body 29 and the embolus 28 are fitted (the ignition means 3 is assembled).
In powder or granular form so as not to cut the bridge line at
It is preferable that In addition, the load of ignition powder is
It can be set appropriately to increase the flame power to be ejected.
It is preferable to load a sufficient amount. Also, the set of each component
It is also possible to adjust the composition ratio to obtain high flame power.
Wear.

Two electrode pins 22 protruding from the embolus 28
Are arranged in parallel with the axis of the embolus 28 and penetrate through the embolus 28. Each electrode pin 22 has a shape that is curved outward at the flange portion of the embolus 28 and projects from both ends of the embolus 28. Each of these electrode pins 22 is formed of a single conductive rod material (stainless steel, iron-nickel alloy, etc.). Further, in each electrode pin 22, a bridge wire 25 is welded in the tube body 29 by welding or the like.

The transfer charge 2 has a calorific value of 4000 J / g or more, preferably 5500 J / g or more, such as boron, potassium nitrate, 5-aminotetrazole,
Lead-free gunpowder or the like can be used. With such a composition, the calorific value can be 4000 J / g or more, preferably 5500 J / g or more.
Here, in the case of transfer charge having a calorific value of less than 4000 J / g,
The rupture disk 6 that seals the cylinder 1 bursts,
Due to adiabatic expansion of the released gas, it becomes difficult to heat it sufficiently when the temperature is lowered. For this reason, it is necessary to increase the amount of the transfer charge 2, and the gas generator P1 cannot be downsized.

As shown in FIG. 1, the outer tubular member 5 is formed of a metal material such as stainless steel or aluminum into a cylindrical shape. The housing 4 is fitted to one end of the outer tubular member 5, and a stepped portion is formed on the housing 4. It is fixed to 11 by caulking. The other end of the outer cylinder member 5 has a reduced diameter first step portion 19 of the cylinder 1.
It is inscribed and fitted in and is welded and fixed by welding or the like. A gas retention space 16 is formed between the rupture disc 6 and the bottom portion 7 of the housing 4. The filter material 10 is disposed on the outer peripheral portion of the gas retention space 16, that is, on the inner peripheral portion of the outer tubular member 5.

This filter material 10 is formed into a cylindrical shape having an outer diameter substantially the same as the inner diameter of the outer tubular member 5 by, for example, an assembly of knitted wire mesh, plain weave wire mesh and crimp woven metal wire. The gas release holes 1 are provided at predetermined intervals around the outer cylinder member 5 at the portion where the filter member 10 contacts.
7 are formed. In addition, this filter material 10
The inner peripheral portion thereof is in contact with the outer periphery of the cylinder cap 23, is stretched from the cylinder 1 to the housing 4, and is installed so as to cover the gas retention space 16. As a result, all the gas from the cylinder passes through the filter material 10 and is discharged from the gas discharge hole 17.

In this way, the cylinder 1 and the housing 4 are
Since they are fitted and fixed by the outer cylinder member 5 made of the same cylinder, they are connected and held coaxially with their respective axes aligned. Thereby, the ignition means 3 and the flame outlet 1
3. The center of the rupture disc 6 is coaxial, and the flame from the ignition means 3 is concentrated on the center of the rupture disc 6.

Further, since the filter material 10 is provided so as to cover the outer periphery of the gas retention space 16 formed between the cylinder 1 and the housing 4, the gas retention space 16 is
The gas from the cylinder 1 and the high-temperature gas from the housing 4 are efficiently mixed and are discharged from the gas discharge hole 17.

Next, the operation of the gas generator P1 will be described with reference to FIG. The gas generator P1 shown in FIG. 1 is assumed to be directly or indirectly connected to the airbag device on the shaft end side of the housing 4.

When the collision sensor detects an automobile collision,
As shown in FIG. 1, the gas generator P1 energizes and ignites the ignition means 3. The flame of the ignition means 3 bursts along, for example, a cross-shaped notch provided on the end face 24,
It is ejected into the combustion chamber 12 from the center of the end surface 24 of the ignition means 3. The flame that has passed through the combustion chamber 12 has a flame outlet 13
The flame force is increased by the restriction of No. 3, and the metal seal tape provided at the outlet of the flame discharge port 13 is instantly melted and concentrated on the central portion of the rupture disc 6,
The rupture disc 6 is burst at once. The gas released from the rupture disk 6 flows out into the gas retention space 16. At this time, the released gas undergoes adiabatic expansion in the gas retention space 16, so that the temperature drops sharply. At this time, the gas released from the cylinder 1 is the filter material 10 provided around the gas retention space 16,
Without being released from the gas release hole 17 at once,
The gas is retained in the gas retention space 16. Then, it is mixed with a high temperature gas from the ignition means 3 described later and heated.

On the other hand, the flame from the ignition means 3 burns the transfer charge 2 in the combustion chamber 12. The high-temperature heat flow generated thereby flows into the gas retention space 16 and the cylinder 1
It mixes with the cooled gas released from. The gas discharged from the cylinder 1 is heated by this, becomes a high temperature gas, passes through the filter material 10, and is discharged from the gas discharge hole 17 formed in the outer cylinder member 5. With this, the airbag connected to the gas generator P1 instantly receives the clean gas released from each gas release hole 17,
Is inflated.

As described above, according to the gas generator P1 of the present invention, since the heat transfer amount of the transfer charge 2 is 4000 J / g or more, preferably 5500 J / g, the charge amount of the transfer charge 2 can be reduced, The combustion chamber 12 can be downsized. As a result, the distance between the rupture disc 6 and the ignition means 3 can be shortened, and the rupture disc 6 can be shortened.
By making the ignition means 3 and the ignition means 3 face each other, the flame of the ignition means 3 can be directly applied to the rupture disk 6. Therefore, the capacity of the combustion chamber can be reduced as compared with the conventional case where the rupture disk is destroyed by increasing the pressure in the combustion chamber by the gas generated by burning the transfer charge stored in the combustion chamber. Can be converted.

Further, the gas discharge hole 13 is formed in the bottom portion 7 of the housing 4 so that the flame generated by the ignition means 3 is concentrated and hits the central portion of the rupture disk 6, so that the conventional case is as follows. Even if the rupture disk 6 having high mechanical strength is used, the flame can be surely ruptured by the flame without using a mechanical means such as a piston. Therefore, the structure of the gas generator P1 can be simplified.

Further, since the filter material 10 is provided so as to extend from the cylinder 1 to the housing 4 so as to cover the gas retention space 16 formed between the cylinder 1 and the housing 4, it is jetted from the cylinder 1, The adiabatically expanding gas can be efficiently heated by the high temperature gas from the ignition means 3.

The gas generator P1 of the present invention is, of course, not only an airbag, but also a disconnection safety switch for disconnecting the in-vehicle power supply network from the automobile battery in the event of an accident that triggers the safety system such as a seat belt pretensioner. Can also be used as

[0033]

As described above, the gas generator of the present invention has the following features.
The rupture disk having high breaking strength with excellent sealing property of the cylinder charged with high pressure gas by the flame from the ignition means is destroyed, and the high pressure gas released from the cylinder and the high temperature gas generated in the combustion chamber are separated. It is a structure that mixes and efficiently heats and adiabatically expands the gas ejected from the cylinder. Therefore, it is not necessary to increase the amount of transfer charge or use a mechanical means to destroy the rupture disk, so that the structure can be simplified and the size can be reduced. In addition, it is possible to use a gas generator of a hybrid system that releases a sufficiently heated gas.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of an embodiment of a gas generator according to the present invention.

[Explanation of symbols]

P1 gas generator 1 cylinder 2 transfer charge 3 Ignition means 4 housing 5 Outer cylinder material 6 rupture disc 7 bottom 8 side tube 10 Filter material 11 steps 12 Combustion chamber 13 Flame outlet 16 gas retention space 17 Gas release hole

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryo Kodama             3903-39, Toyotomi-cho, Himeji-shi, Hyogo Prefecture             Himeji Factory of Yakuhin Co., Ltd. F-term (reference) 3D018 MA00                 3D054 DD02 DD04 DD17 DD18 DD22                       DD30 EE36                 4G068 DA08 DB01 DB04

Claims (2)

[Claims] 1. A cylinder (1) charged with high-pressure gas, a cup-shaped housing (4) containing a donut-shaped transfer charge (2) and an ignition means (3), and the cylinder (1). A rupture disc (6) for holding and sealing pressure, and the cylinder (1) and the housing (4) so as to form a gas retention space (16) between the cylinder (1) and the housing (4). ) Outer cylinder material (5) for connecting and holding
In the gas retention space (16), the gas adiabatically expanded and ejected from the cylinder (1) is heated by the high temperature gas from the ignition means (3), and the outer cylinder material ( Gas generation, characterized in that the gas passes through a filter material (10) provided along the inner wall of (5) and is released from a gas release hole (17) provided in the outer tubular material (5). vessel. 2. The gas generator according to claim 1, wherein the rupture disc (6) is broken by the flame force from the ignition means (3).