JP2001191891A - Electric initiator and gas generator for pretensioner formed using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric initiator easily manufactured while ensuring reliability when actuated. SOLUTION: This electric initiator has an igniter 7 ignited by the heating of a bridge wire 3, and a cavity 5 for storing the igniter 7. The cavity 5 is formed into cylindrical shape, and its open end 42 is closed with a cover member 6. The cover member 6 is formed of a separate body from a peripheral wall part 4 forming the cavity 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric initiator which is operated by an electric signal at the time of a collision, and more particularly to an electric initiator used for a gas generator for an air bag and a seat belt pretensioner which is a safety system for an automobile. Regarding the expression initiator.

[0002]

BACKGROUND OF THE INVENTION Airbags and seatbelt pretensioners play an important role in reducing deaths or injuries from collisions. The initiator is operated by an electric signal from the collision detection system, and has a function of starting the operation of these safety devices.

[0003] Previously, electrical initiators are known to include a number of components, most of which have a header and a cup portion that are joined to form a cavity. The initiator also has one or more conductive pins that provide a conductive path from outside the header and cup to the cavity. An electric resistance member called a bridge wire is arranged inside the cavity, and a conductive pin is connected to the electric resistance member. In the vicinity of the bridge wire, there is disposed a compound called a primer, which is very sensitive to temperature. Another compound called an output charge (or igniter) is also contained in the cavity adjacent to the primer.

[0004] An initiator having such a structure is as follows.
The operation starts when an electric signal is transmitted to the conductive pin. The bridgewire can convert the electrical energy in the signal to thermal energy, which increases the temperature of the resistor and initiates the firing reaction of the primer. The firing reaction of the primer causes the firing reaction of the output charge, and the pressure and heat buildup created by these reactions causes the cup to rupture, releasing hot gases and particles out.

In the gas generator for an air bag, the hot gas and particles released from the initiator in this manner ignite a solid gas generating agent to generate gas, thereby inflating the air bag. In the seat belt pretensioner, the piston is moved to perform the seat belt retraction operation. Therefore, in order to reliably operate these safety devices, it is important that the initiator be reliably operated.

Therefore, various initiators have been proposed to provide a reliable and low-cost electric initiator. For example, in the electric initiator disclosed in Japanese Patent Application Laid-Open No. 9-504599, in order to solve the above-mentioned problems, the structure of the pin, the mounting of the pin to the header, the mounting of the header to the cup, the mounting of the resistor to the pin It is intended to improve the reliability of the initiator by selecting the mounting, the structure of the resistor, and the output charge and primer. However, with the initiators proposed so far, there is still room for improvement if sufficient operation reliability is ensured and further consideration is given to manufacturability.

Further, conventionally, the header is formed using a metal or a resin. Among them, the header formed using a metal is difficult to manufacture and process. Further, in a header formed using resin, conventionally, nylon 6 is used as a resin material.
In the header formed by using, the igniting charge (explosive) absorbs and deteriorates due to the permeation of moisture, and depending on the use environment, it is conceivable that the initial performance of the initiator may not be obtained after long-term use.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to
An object of the present invention is to provide an electric initiator which ensures reliability during operation and is easy to manufacture.

[0009]

The electric initiator according to the present invention is particularly characterized by a structure for forming a cavity for accommodating an ignition charge and a material of a header for holding a conductive pin. In particular, in an electric initiator characterized by a structure that forms a cavity, a bridge wire that converts electric energy into heat energy, a contact with an igniter that ignites and burns by the heat of the bridge wire, and a bridge wire , Ensuring the connection with the conductive pins that transmit electrical energy to this bridge wire,
Further, the electric initiator eliminates a gap between the conductive pin and the header holding the conductive pin. The electric initiator can be used for a gas generator for an airbag or a seat belt pretensioner, and the operation reliability of these safety devices can be improved.

That is, an electric initiator according to the present invention is an electric initiator having an igniter ignited by the heat generated by a bridge wire and a cavity for accommodating the igniter, wherein the cavity is formed in a cylindrical shape. The opening end is closed by a cover member, and the cover member is formed separately from the peripheral wall portion forming the cavity. The cavity for accommodating the ignition charge is defined by a cylindrical charge holder forming a peripheral wall portion, a header closing one end opening of the charge holder, and a cover member closing the other end opening of the charge holder. Can be.

The charge holder that forms the peripheral wall of the cavity and the header that closes one of its open ends can be formed separately from each other, or both can be formed integrally. That is, the charge holder and the header can be integrally formed by injection molding or the like, or the charge holder and the header can be formed separately from each other, and then both can be connected.

However, in this initiator, the open end of the cavity serving as the ignition charge accommodating space (that is, the end face located on the side opposite to the end face of the charge holder closed by the header).
Is required to be formed separately from the charge holder. This is to press the ignition charge on the opposite side of the cover member in the cavity and then close the cavity with the cover member. In this manner, the ignition charge is pressed on the opposite side of the cover member in the cavity. By doing so, the contact between the ignition charge and the bridge wire can be ensured.

That is, the charge holder is closed by a header and a cover member arranged opposite to each other, and the end of the conductive pin inserted into the header is usually provided on the side of the cavity opposite to the cover member. Have been placed. A bridge wire capable of converting electric energy to heat energy is connected to the conductive pin. Therefore, by pressing this igniter on the bridge wire side, that is, on the side opposite to the cover member, the contact between the igniter and the bridge wire can be ensured. If the bridge wire is heated by electric energy, reliable ignition of the igniter can be expected.

Further, by bringing the igniting charge into direct contact with the bridge wire, a primer such as lead styphnate, which was conventionally disposed near the bridge wire for burning the igniting charge, becomes unnecessary, and the initiator is used. In a given environment, the source of lead can be removed. As a result, with such features, an initiator that is easy to manufacture and has a reliable operation can be realized without generating any lead by the operation.

[0015] The header closing the end face of the cavity containing the ignition charge holds conductive pins for transmitting electric energy to the bridge wire. This header is 2
Water absorption rate after water immersion at 3 ° C for 24 hours is 0.005 to
1.0% and a tensile strength (MPa) of 100 to 25
It is preferably formed using a resin material that is zero. The water absorption of the resin material forming this header member (2
(After immersion in water at 3 ° C. for 24 hours)
It is 0.5%, more preferably 0.01 to 0.1%. Also, the tensile strength (MPa) of this resin material is more preferably 160 to 250, and still more preferably 170 to 230.

The above-described initiator is configured such that, for example, two conductive pins are inserted into a header, and the ends of the two conductive pins appear on the end face of the header. The ends of the conductive pins are connected by a bridge wire so as to be able to conduct electricity, and an ignition charge is pressed so as to come into contact with the bridge wire. The charging of the igniting charge can be performed by a method in which a cylindrical charge holder for forming a cavity is attached to the header, and the internal space (in the cavity) is charged with the igniting charge. Thereafter, a cover member is connected to the open end of the charge holder, and the cavity in which the ignition charge is stored is closed. When the conductive pin receives the electric signal, the bridge wire generates heat and ignites and burns the igniting charge, and the flame ruptures a container forming a cavity containing the igniting charge and is discharged to the surroundings.

According to the present invention, there is provided, in connection with the above-described electric initiator, an electric initiator characterized by a material of a header for holding the conductive pins. More specifically, in such an electric initiator, a header that holds a conductive pin and closes an end face of a cavity that stores an ignition charge is formed using a specific resin material.

That is, an electric initiator comprising a conductive pin for transmitting electric energy to a bridge wire and a header for holding the conductive pin, wherein the header is formed using a resin material. The resin material has a water absorption of 0.03 after immersion in water at 23 ° C. for 24 hours.
And the tensile strength (MPa) is 100%.
２５０250 is an electric initiator.

As such a resin material, a liquid crystal polymer (LCP) containing an inorganic filler such as polybutylene terephthalate (PBT), polyphenylene sulfide (PPS) or mineral containing glass fiber and other inorganic fillers is used. Can be used. When these resin materials are used, polybutylene terephthalate (PBT) contains 20 to 80% by weight of glass fiber, and polyphenylene sulfide (PPS) contains 20 to 80% by weight of glass fiber, In addition, a liquid crystal polymer (LCP) preferably contains 20 to 80% by weight of minerals. In particular, when forming using a glass reinforced resin containing glass fiber, it is desirable that the orientation of the glass fiber is adjusted so as to be along the drawing direction of the conductive pin inserted into the header. Also,
The content of the inorganic filler material in each resin material is more preferably 30 to 50% by weight.

The electric initiator in which the header is formed in this manner is easier to manufacture and can further reduce the manufacturing cost as compared with the case where the header is formed using metal. Further, when the header is formed using the above-described resin material, it is possible to avoid the situation in which moisture permeates the header and the igniter absorbs moisture and deteriorates as much as possible. In other words, if such a header is used, the initial initiator performance can be exhibited even when the header is left for a long time in an automobile environment.

The electric initiator constructed as described above includes a collar member for fixing the electric initiator,
A cup member having a lower opening fixed to the collar member to partially surround the initiator; and a gas generating agent filled in a space between the cup member and the electric initiator and ignited and burned by the operation of the initiator. In addition, a gas generator for a pretensioner can be configured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment of the present invention. FIG. 1 is an exploded view showing one embodiment of the electric initiator of the present invention.

The electric initiator shown in this figure inserts two conductive pins 2 exposing a flange-shaped head 21 at the end of the header 1 into a header 1 formed using glass fiber reinforced resin. The heads 21 of the conductive pins are connected to each other so as to be able to conduct electricity with the bridge wire 3. It is desirable that the two be connected by resistance welding. It is also possible to connect both by soldering,
In this case, since additional materials (such as solder and flux) are required, the production becomes more difficult and expensive. The spacing between the flange-shaped heads 21 of the conductive pins 2 is adjusted. The conductive pins 2 are inserted into the header 1, and knurls (concavo-convex, ridges or bumps formed in the circumferential direction) are provided between the header and the conductive pins in order to prevent outside air from entering or gas leakage between the header and the conductive pins. ) Is desirable.

The header 1 is formed of a resin material having a water absorption of 0.005 to 1.0% after immersion at 23 ° C. for 24 hours and a tensile strength (MPa) of 100 to 250. . As such a resin material, glass fiber is 30
% By weight of polybutylene terephthalate (water absorption of 0.07% after immersion in water at 23 ° C. for 24 hours, tensile strength of 132
MPa), polybutylene terephthalate containing 45% by weight of glass fiber (water absorption after immersion in water at 23 ° C. for 24 hours: 0.07%, tensile strength: 156 MPa);
0% by weight of polyphenylene sulfide (23 ° C.
Water absorption after water immersion for 24 hours at 0.015%, tensile strength 1
96 MPa) and a liquid crystal polymer containing 50% by weight of a mineral (water absorption of 0.0
4%, a tensile strength of 171 MPa) can be used.

The header 1 includes a head 2 of the conductive pin 2
The end face on the side exposing 1 is formed as a cylindrical projection. A protruding portion of the header 1 (hereinafter, referred to as a cylindrical end portion 11) is internally fitted into the charge holder 4 formed in a substantially cylindrical shape, and serves as a joint portion between the header 1 and the charge holder 4. The connection between the two can be joined by ultrasonic welding.

The cavity 5 includes an end surface of the cylindrical end portion 11 of the header and the charge holder 4, and the ignition charge 7 ignited and burned by the bridge wire 3 generating heat by electric energy is formed therein. Is filled. As such an ignition charge, a zirconium / potassium perchlorate mixture (ZPP) is preferably used.

In this embodiment, the outer end of the open end 41 of the charge holder 4, that is, the end opposite to the side into which the circular end 11 of the header is fitted is cut out in a stepped shape. Is formed. A cover member 6 formed separately from the charge holder 4 constituting the peripheral wall of the cavity 5 is fitted to the outside of the stepped portion 42, and the charge holder 4 and the cover member 6 are joined by ultrasonic welding. ing. As a result, the cavity 5 in which the ignition charge 7 is stored is closed, so that the cavity 5 is isolated from the external environment. The cover member 6 is composed of a circular portion 61 for closing the cavity 5 and a peripheral wall portion 62 joined to the stepped portion 42. The circular portion 61 is formed to be partially thin or to have a groove. The fragile portion 63 realized by the above is formed, and the peripheral wall portion 62 is provided with a projection 64 which is connected to the stepped portion 42 of the charge holder 4. When the igniter 7 burns, the fragile portion 63 ruptures preferentially to other wall portions, and can regulate the direction in which the flame / gas is blown out. If the direction of ejection of the flame or the like is regulated in this manner, the heat energy of the flame or the like is intensively released, so that the ignition of the gas generating agent can be ensured. Further, since the projection 64 is joined to the stepped portion 42, welding can be easily and reliably performed.

The bridge wire 3 generates heat by electric energy (ie, an operation signal) input through the conductive pin, and has a resistance. This bridge wire 3 can also be formed using one or more metals (lines). The bridge wire 3 may be formed using a nickel-chromium-iron alloy called Nichrome, or may be formed using another metal such as stainless steel or platinum. Nichrome is particularly preferred because it has a large temperature coefficient of resistance (TCR) and is excellent in welding.

In operation of the electric initiator, when an operation signal is received from a connector (not shown) connected to the conductive pin 2, the operation signal is transmitted to the bridge wire 3 via the conductive pin 2. The bridge wire 3 heated by the electric energy (i.e., the operation signal) ignites and burns the igniter 5 and discharges the flame, gas, and the like to the outside. At this time, the fragile portion 6
Due to the formation of 3, the portion is preferentially damaged, thereby restricting the direction in which the flame or gas is ejected.

As described above, the electric initiator in which the cavity 5 accommodating the ignition charge 7 is closed by the cover member 6 can be manufactured by, for example, the steps shown in FIGS.

First, a header 1 made of a resin material having a water absorption of 0.005 to 1.0% after immersion at 23 ° C. for 24 hours and a tensile strength (MPa) of 100 to 250 is used.
Then, the header assembly formed by inserting two conductive pins 2 is polished (FIG. 2A). Next, the bridge wires 3 are arranged between the flange-shaped heads 21 of the conductive pins 2 (FIG. 2B), connected by resistance welding, and bridge wire (B / W) welding. A sub-assembly is formed ((b) → (c) in the figure). Next, the cylindrical charge holder 4 is arranged on the head 21 side of the conductive pin 2 of the bridge wire (B / W) welding sub-assembly and joined by ultrasonic welding, and the ignition charge 7 is pressed into the charge holder 4. To form a charge holder (C / H) welding subassembly ((c) → (d) in the figure). Next, during the charge holder (C / H) welding sub-assembly, the cover member 6 is joined / closed by ultrasonic welding to the opening end of the charge holder 4 (that is, the stepped portion 42) to form an initiator (FIG. 3 (d)). → (e)). In the embodiment shown in this figure, a projection 64 is provided on the peripheral wall portion 62 of the cover member 6, and this is connected to the stepped portion 42 of the charge holder 4, so that both are fitted and connected before welding. You can do it.

In the initiator formed as described above, a collar 13 is disposed on the opposite side of the initiator from the charge holder 4 with a gasket 12 interposed therebetween.
An initiator can be formed by press-fitting the initiator and caulking the end portion 14 of the initiator accommodating opening of the collar 13 to integrate the two (FIG. 2 (e) →
(g)). It is desirable that the end portion 14 of the initiator accommodating port is formed so as to shorten a claw (that is, a portion to be swaged) and prevent discharge of focus when static electricity is applied. If the distance between the nail and the pin is short at the time of applying static electricity, there is a danger that discharge will occur between the claws and the pin to ignite the explosive. Therefore, by increasing the distance between the nail and the pin, it is possible to prevent discharge at this portion.

The initiator assembly thus formed can be used as a component for manufacturing a gas generator used for a seat belt pretensioner. A gas generator for a pretensioner using this initiator assembly can be manufactured, for example, by the steps shown in FIGS.

First, a cup member 20 having a bottomed cylindrical body having an open end 23 bent in a flange shape is provided with a gas / fuel mixture by the operation of an initiator, more specifically, the combustion of an ignition charge.
The gas generating agent 22 which is ignited and burned by a flame or mist is filled (FIG. 2 (f)). Next, a sealant (sealing material or waterproofing agent) is injected into the circular groove 15 provided in the collar 13 of the initiator assembly shown in FIG. 2 (g), and the flange portion 23 of the cup member 20 is fitted into the circular groove. The circular groove 15
The initiator assembly and the tubular member 20 are connected by caulking the peripheral wall of the cylindrical member. At that time, the charge holder 4 side of the initiator assembly is press-fitted into the cup-shaped member ((g → h) in the figure). Thus, the gas generator for the pretensioner is almost completed. However, in FIG. 2, in order to easily and reliably connect a connector (not shown) for transmitting an operation signal to the gas generator, a side of the initiator is used. In
The retainer 30 is arranged (FIG. 7 (h)). As the retainer 30, a known one having a function of positioning a connector to be joined to the conductive pin 2 and a function of holding and fixing the connector can be used.

In the gas generator for a pretensioner (FIG. 3) formed as described above, an initiator operates by transmitting an ignition current to the conductive pin 2, and generates a flame, a gas, a mist or the like due to the combustion of the ignition charge 7. generate. These flames ignite and burn the gas generating agent 22 housed in the chamber (combustion chamber 24) inside the cup member 20 to generate operating gas. This working gas then ruptures the cup member 20 and is released outside.

In particular, as shown in FIG. 2 (g), the sealant is filled in the connecting portion between the initiator assembly and the cup member, that is, in the present embodiment, the circular groove 15 is accommodated in the cup member 20. The gas generating agent 24 can be protected from moisture.

[0037]

According to the present invention, it is possible to realize an initiator device which ensures reliability during operation and is easy to manufacture.
Particularly, in the electric initiator according to the present invention, since the inside of the cavity accommodating the igniting charge is closed by the cover member, the igniting charge ignited and burned by the heat energy of the bridge wire is closed by the cover member. From the side, it can be pressed into the cavity. Since the bridge wire is provided on the side of the cavity where the igniting charge is pressed, the igniting charge and the bridge wire surely come into contact with each other and that state is maintained.
Further, by forming in this manner, the ease of manufacture is improved.

Further, a header for holding the conductive pins is
Water absorption rate after water immersion at 23 ° C for 24 hours is 0.005 to
1.0% and a tensile strength (MPa) of 100 to 25
When it is formed of a resin material of 0, it is easy to manufacture and reduces the manufacturing cost, and can maintain the initial performance even if it is used for a long time in an automobile environment. Become an initiator.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an electric initiator according to the present invention.

FIG. 2 is a schematic view showing an example of a manufacturing process of a gas generator for a pretensioner using the electric initiator of FIG.

FIG. 3 is a longitudinal sectional view showing one embodiment of a gas generator for a pretensioner of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Header 2 Conductive pin 3 Bridge wire 4 Charge holder 5 Cavity 6 Cover member 7 Ignition charge 13 Collar 20 Cup member 22 Gas generating agent

Claims (11)

[Claims] 1. An electric initiator having an igniter ignited by the heat generated by a bridge wire and a cavity for accommodating the igniter, wherein the cavity is formed in a cylindrical shape, and an open end thereof is a cover member. An electric initiator, wherein the cover member is formed separately from a peripheral wall portion forming a cavity. 2. The cavity is formed by a cylindrical charge holder forming a peripheral wall portion, a header closing one end opening of the charge holder, and a cover member closing the other end opening of the charge holder. The electric initiator according to claim 1. 3. The igniter charged in the cavity,
The electric initiator according to claim 1, wherein the electric initiator is pressed on a side opposite to the cover member. 4. A bridge wire, which is connected to the conductive pin and is capable of converting electric energy into heat energy, is disposed in the cavity, and the igniter contained in the cavity is provided in the cavity. The electric initiator according to claim 1, wherein a pressure is applied to a side on which the bridge wire is disposed. 5. The electric initiator according to claim 4, wherein said igniting charge comprises a mixture of zirconium / potassium perchlorate (ZPP), said igniting charge being in direct contact with said conductive pin. 6. The header is made of a resin material, and the resin material has a water absorption of 0.005 to 1.0% after immersion in water at 23 ° C. for 24 hours, and has a tensile strength ( The electric initiator according to any one of claims 2 to 5, wherein MPa) is 100 to 250. 7. An electric initiator including a conductive pin for transmitting electric energy to a bridge wire and a header for holding the conductive pin, wherein the header is formed using a resin material. , The resin material is
Water absorption rate after water immersion at 23 ° C for 24 hours is 0.005 to
1.0% and a tensile strength (MPa) of 100 to 25
0 electrical initiator. 8. The resin material is a polybutylene terephthalate (PBT), a polyphenylene sulfide (PPS) or a liquid crystal polymer (LCP) containing an inorganic filler material.
The electric initiator according to claim 6, wherein: 9. The resin material according to claim 1, wherein the glass fiber is 20-80.
8. The electric initiator according to claim 6, wherein the electric initiator is polybutylene terephthalate (PBT) containing 20% by weight of glass fiber, polyphenylene sulfide (PPS) containing 20 to 80% by weight of glass fiber, or a liquid crystal polymer (LCP) containing 20 to 80% by weight of mineral. . 10. An electric initiator, a collar member for fixing the electric initiator, a cup member for fixing a lower opening in the collar member and partially surrounding the initiator, and an electric initiator for the electric member. The space between the initiators is filled and ignited by the operation of the initiator.
A gas generator for a pretensioner, comprising: a burning gas generating agent; and wherein the electric initiator is the electric initiator according to any one of claims 1 to 9. 11. A step of attaching a cylindrical charge holder for forming a cavity to a header for holding a conductive pin, a step of pressing an igniter into an internal space of the charge holder, Closing the end opening with a cover member and closing the cavity.