JP2010208390A - Small gas generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small gas generator capable of maintaining airtightness inside a case filled with a gas generating agent without increasing the number of parts, and improving the ignition performance of the gas generating agent inside the case. <P>SOLUTION: A header 33 of an igniter body 30 is covered with a small diameter part of a cup-shaped case 20, and is integrated by welding at a welding part 38. The welding part 38 is surrounded and protected by an igniter collar 50. Therefore, entrance of moisture into a filling chamber 80 in the case 20 is prevented, so that there is no need of a sealing material of an O-ring and the like for maintaining airtightness and its mounting operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a small gas generator used for a seat belt pretensioner or the like.

  A structure in which a small gas generator used for a seat belt pretensioner or the like is attached to a case containing a gas generating agent in the vicinity of an electric igniter is generally known. The case has a cup shape, and a structure for fixing the open end of the case to an igniter collar to which an electric igniter is attached is well known.

  Patent Document 1 discloses a gas generator 1 used for a seat belt pretensioner or the like. The 1st cup 2 in which the gas generating agent 3 was accommodated is attached with respect to the igniter 4, and the opening end of the 1st cup 2 is the diameter expansion skirt part 2c. The diameter-enlarged skirt portion 2c has a flange shape that opens to the outside, is overlaid on the plug body 16 of the igniter 4, and is caulked and fixed by the projecting portion 23 of the igniter collar. And the O-ring 19 is arrange | positioned between the 1st cup 2 and the igniter 4, and the inside of the cup 2 is hold | maintained airtightly.

  Since the gas generator of Patent Document 1 requires the O-ring 19 as a separate member in this way, the number of parts increases. Moreover, after caulking the projection 23, it is not possible to visually confirm whether the O-ring 19 is in a strictly sealed state, or the O-ring 19 may be slightly displaced due to caulking work.

  In Patent Document 2, an output can 206 containing liquid fuel is further attached to the squib 198 attached to the squib housing 200. The output can 206 has an opening fixed to the squib, and the diameter of the peripheral wall is larger than the diameter of the opening. For this reason, an annular gap is formed between the peripheral wall portion and the ignition holder 204, and the liquid fuel that has entered the gap is less likely to ignite.

  Patent Documents 3 and 4 are inventions of igniters, but the periphery of the header of the igniter main body is fixed and held only with resin away from the collar, so when applied to a gas generator of a vehicle However, there is a possibility that the airtightness may be lowered due to deformation or the like of the resin portion due to heat or pressure during operation.

WO 2002/092400 US Pat. No. 5,496,062 US Pat. No. 5,558,366 US Pat. No. 5,556,132

  The present invention provides a small gas generator capable of maintaining the airtightness inside the case filled with the gas generating agent without increasing the number of parts, and improving the ignition performance of the gas generating agent inside the case. The issue is to provide.

[Claim 1]
As a means for solving the problems, the present invention
An igniter main body, an igniter in which a substantially cylindrical igniter collar for fixing the igniter main body is integrally molded with a resin, and a cup-shaped case forming a filling chamber filled with a gas generating agent. Gas generator,
The igniter main body has a bridge wire that glows red by an ignition current, and an igniting agent accommodated in contact with the bridge wire, in a header to which a conductive pin is fixed,
The cup-shaped case is composed of a small-diameter portion located on the opening side, a large-diameter portion located on the bottom side, and an annular slope between the small-diameter portion and the large-diameter portion,
By being welded and integrated with the small diameter portion covering the header, airtightness of the inside of the filling chamber is secured without using a sealing material,
The boundary between the small-diameter portion and the annular slope portion is located at the same height as the upper end of the header, or higher.
A gas generator is provided in which the igniter collar is disposed so as to surround a welded portion between the cup-shaped case and the header.

  The cup-shaped case is composed of three parts with different diameters in the radial direction. The space surrounded by the large-diameter part and the annular slope is the gas generating agent filling chamber, and the small-diameter part is the header of the igniter body. It is inserted. And the small diameter part and the header are welded and integrated. Since the presence of the welded portion completely prevents moisture from entering the filling chamber, the igniter and gas of the igniter main body can be provided without arranging sealing means such as an O-ring as in Patent Document 1. The generator is prevented from absorbing moisture.

  The annular slope is preferably a flat surface, but may have irregularities on the surface, may be a convex curved surface on the filling chamber side, or may be a convex curved surface on the opposite side, and the curved surface may be a surface. May have irregularities.

  Further, a boundary portion between the small diameter portion and the annular slope portion is located at the same height as or higher than the upper end of the header. By adopting such a positional relationship, as shown in Patent Document 2, an annular gap is not formed in the outer space of the header portion. Therefore, the flame, high temperature gas, etc. which generate | occur | produce from an igniting agent are not blocked | interrupted by a header part, but are efficiently transmitted to the surrounding gas generating agent, and ignitability is improved.

  Further, the igniter collar is disposed so as to surround a welded portion between the cup-shaped case and the header. By doing so, the igniter collar functions to protect the welded part through the resin for more than 10 years, which is the service life of the automobile, and when heat or pressure is applied during operation However, the cup-shaped case and the header are prevented from being destroyed at the welded portion. In particular, in the gas generator of the present invention, unlike the igniters of Patent Documents 3 and 4, since the gas generating agent is contained in the cup-shaped case, a large pressure is applied to the cup-shaped case during operation. However, even when pressure is applied to the cup-shaped case, the igniter collar prevents the cup-shaped case from spreading from the welded portion, so the cup-shaped case or header may be destroyed at the welded portion. This prevents gas leakage.

  From the viewpoint of further strengthening the protection function of the welded portion by the metal collar, the substantially cylindrical igniter collar includes a lower annular wall portion that houses the conductive pin, an upper cylindrical wall portion that surrounds the header, An inward flange portion extending inwardly from between the lower cylindrical wall portion and the upper cylindrical wall portion, the upper cylindrical wall portion facing the side surface of the header, and the inward flange portion It is preferable that a part of is arranged so as to face the bottom surface of the header on the conductive pin side.

  The cup-shaped case includes a small-diameter portion located on the opening side, a large-diameter portion located on the bottom surface side, and an annular flat portion between the small-diameter portion and the large-diameter portion, and the small-diameter portion and the annular shape A thing with the same height position of the axial direction of the boundary part with a plane part and the boundary part of the said large diameter part and the said annular plane part can also be used. The annular flat portion is preferably a flat surface, but may have irregularities on the surface, may be a convex curved surface on the filling chamber side, may be a convex curved surface on the opposite side, and the curved surface is the surface. May have irregularities.

  Further, the cup-shaped case may be covered with resin so that the case is electrically insulated to prevent malfunction of the igniter body.

  According to the gas generator of the present invention, the airtightness of the space filled with the gas generating agent can be ensured, and the ignitability of the gas generating agent can also be improved.

The axial direction sectional view of the gas generator of the present invention. FIG. 3 is an axial sectional view of the cup-shaped case used in FIG. 1. Axial sectional view of a cup-shaped case of another embodiment of the present invention.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1 is an axial sectional view of a small gas generator used for a seat belt pretensioner. The gas generator 10 is a combination of an igniter body 30 and a cup-shaped case 20.

  The igniter main body 30 is a known one in which two conductive pins 31 and 32 for guiding an ignition current are connected to a header 33. An annular charge holder 40 attached to the header 33 is disposed on the upper surface 37 side of the metal header 33, and a recess 42 for accommodating the ignition agent is formed therein.

  A bridge wire (not shown) is disposed on the bottom surface of the recess 42 and filled with an igniting agent 44 (a mixture of zirconium and potassium perchlorate) in contact with the bridge wire from above. The surface of the ignition agent 44 is in an exposed state, but may be covered with a cover material.

  A cylindrical igniter collar 50 exists outside the igniter body 30. The igniter collar 50 includes a lower annular wall portion 52 that accommodates the conductive pins 31 and 32, an upper cylindrical wall portion 54 that surrounds the header 33, and a lower cylindrical wall portion 52 and an upper cylindrical wall portion 54. An inward flange portion 56 extending inward from the inside is formed. The inward flange portion 56 forms a hole through which the conductive pins 31 and 32 pass in the center portion.

  The igniter body 30 is integrated with the igniter collar 50 by a resin 60. As the resin, for example, a resin described in paragraph No. 20 of JP-A No. 2003-161599 can be used.

  The diameter of the hole formed by the inward flange portion 56 is smaller than the outer diameter of the header 33. This prevents the igniter body 30 from falling off the collar 50 even when the resin 60 is melted and melted and pressure is applied.

  The cup-shaped case 20 is made of metal and is combined by covering the igniter body 30 from the opening 22. Inside the cup-shaped case 20, a filling chamber 80 filled with a known gas generating agent 70 is formed. As described above, since the surface of the igniting agent 44 is exposed, a part of the igniting agent 44 and the gas generating agent 70 are in contact with each other.

  The cup-shaped case 20 has a bottom surface 21 and an opening 22 as shown in the axial cross-sectional shape shown in FIG. 2, and has a small-diameter portion 23 having the smallest outer diameter on the opening 22 side and the most on the bottom 21 side. A large-diameter portion 24 having a large outer diameter and an annular slope portion 25 between the small-diameter portion 23 and the large-diameter portion 24 are included. In the cup-shaped case 20, the axial height positions of the boundary portion 26 between the small diameter portion 23 and the annular slope portion 25 and the boundary portion 27 between the large diameter portion 24 and the annular slope portion 25 are different. The case 20 may be formed with a weak portion on the bottom surface 21 and the large diameter portion 24 so that the case 20 is easily broken during operation.

  The inner diameter of the small diameter portion 23 is substantially equal to the outer diameter of the header 33, and the cup-shaped case 20 is covered with the inner wall surface of the small diameter portion 23 in contact with the outer surface of the header 33. The small-diameter portion 23 and the header 33 are integrated by welding the entire circumference of a part (annular welded portion 38) by laser welding or the like. In FIG. Intrusion of moisture into the filling chamber 80 formed from the slope portion 25 is completely prevented. The cup-shaped case 20 (small diameter portion 23) and the header 30 are both metal, but both may be made of plastic and integrated by ultrasonic welding.

  As shown in FIG. 1, since the annular welded portion 38 is surrounded by the upper cylindrical wall portion 54 and the inward flange portion 56, the upper cylindrical wall portion 54 and the inward flange portion 56 are interposed via the resin 60. Protected.

  The outer diameter of the large diameter portion 24 is larger than the inner diameter of the upper cylindrical wall portion 54 of the collar 50. In other words, even if the pressure becomes high when the resin 60 is melted in operation, the inward flange 56 and the header 33 collide with each other, and the upper cylindrical wall portion 54 and the annular inclined surface portion 25 collide with each other. The main body 30 is prevented from falling off the collar 50.

  The case 20 is attached so that the boundary portion 26 between the small diameter portion 23 and the annular slope portion 25 and the upper end surface 43 of the charge holder 40 (or the upper surface 37 of the header 33) have the same height. For this reason, there is no gap for the gas generating agent 70 to enter between the outside of the charge holder 40 (or the header 33) and the annular inclined surface portion 25, so that combustion products (hot gas) generated by the operation of the igniter main body 30 are formed. , Flame, etc.) are all easily transmitted to the gas generating agent 70, and the ignition and combustion of the gas generating agent 70 are improved.

  In FIG. 1, the structure in which the boundary portion 26 and the upper end surface 43 of the charge holder 40 are substantially at the same position is shown. However, the case 20 is attached to the header 33 so that the boundary portion 26 is positioned above the upper end surface 43. It may be fixed to.

  In FIG. 1, the resin 60 covers not only the igniter body 30 but also the entire surface of the cup-shaped case 20 by injection molding. In this way, the case 20 may be covered by injection molding at one time. For example, a part of the outer periphery of the case 20 (for example, the large diameter portion 24 and the bottom surface 21) is made of the same material as the resin to be injected. A body cup is put in advance, and the igniter body 30 to which the case 20 is attached in that state is attached to the igniter collar 50, the resin 60 is injected, and the heat at that time separates the case 20 A part of the cup can be melted to be integrated.

  In the gas generator 10 shown in FIG. 1, a case 120 having the shape shown in FIG. 3 can be used instead of the case 20 shown in FIG. 2. The cup-shaped case 120 shown in FIG. 3 has the same shape as the case 20 of FIG. 2 except that the portion corresponding to the annular inclined surface portion 25 in FIG. In the cup-shaped case 120 shown in FIG. 3, the axial height positions of the boundary portion 26 between the small diameter portion 23 and the annular flat surface portion 125 and the boundary portion 27 between the large diameter portion 24 and the annular flat surface portion 125 are the same. It is.

  Next, the operation of the gas generator of FIG. 1 will be described. When the ignition current flows through the conductive pins 31 and 32, the bridge wire attached to the upper surface 37 of the header 33 becomes red hot, and the igniting agent 44 in contact is ignited.

  As a result, the combustion products generated from the igniting agent 44 ignite and burn the gas generating agent 70. Then, the pressure inside the case 20 is increased by the generated combustion gas, the case 20 (and the resin covering the case 20) is destroyed, and the combustion gas is discharged to the outside.

  In the gas generator 10, since the gas tightness inside the cup-shaped case 20 (filling chamber 80) is ensured by the annular welded portion 38, the ignition agent 44 and the gas generating agent 70 are sealed from the external environment. Yes.

  In the igniter having a structure in which the molten resin 60 is filled and integrated between the collar 50 and the igniter body 30, when the resin 60 is cooled and contracted, a gap is formed between the collar 50 and the resin 60. Moisture may enter through the gap. For this reason, in the conventional gas generator, a seal member such as an O-ring is disposed (in Patent Document 1, the O-ring 19 is necessary to attach the first cup 2 to the collar). However, in the gas generator 10 shown in FIG. 1, since the airtightness in the case 20 is ensured by the annular welded portion 38, even if a gap is formed between the resin 60 and the collar 50, the filling chamber 80. Moisture does not enter the gas generating agent 70 and the igniting agent 44 without any influence. Further, the annular welded portion 38 is protected by the upper cylindrical wall portion 54 and the inward flange portion 56 of the igniter collar 50 through the resin 60, and the moistureproof effect and the sealing performance are reinforced. Yes.

  For this reason, an extra sealing member is not required, so the number of parts is reduced, and if the annular welded portion 38 is formed using laser welding or the like, the assembly work is less than the work of placing and fixing the O-ring. In addition to being much easier, the durability and reliability of the parts are also improved.

  Further, since the case 20 is attached to the header 33, unlike the case where the first cup 2 is attached to the collar as in Patent Document 1, the dimensional accuracy of the collar 50 is not necessary. For this reason, the manufacture of the collar 50 is facilitated, and the cost of the entire gas generator can be reduced.

  The gas generator of the present invention is suitable as a small gas generator for a seat belt pretensioner, and in addition to that, a gas generator for an actuator used for shock absorbing steering, etc., and a gas generator for a current interrupting device And an ignition means (igniter and transfer agent) of a conventional gas generator for an air bag.

DESCRIPTION OF SYMBOLS 10 Gas generator 20 Cup-shaped case 22 Opening part 23 Small diameter part 24 Large diameter part 25 Annular slope part 30 Igniter main-body part 33 Header 50 Igniter collar 70 Gas generating agent 80 Filling chamber

Claims (5)

An igniter main body, an igniter in which a substantially cylindrical igniter collar for fixing the igniter main body is integrally molded with a resin, and a cup-shaped case forming a filling chamber filled with a gas generating agent. Gas generator,
The igniter main body has a bridge wire that glows red by an ignition current, and an igniting agent accommodated in contact with the bridge wire, in a header to which a conductive pin is fixed,
The cup-shaped case is composed of a small-diameter portion located on the opening side, a large-diameter portion located on the bottom side, and an annular slope between the small-diameter portion and the large-diameter portion,
By being welded and integrated with the small diameter portion covering the header, airtightness of the inside of the filling chamber is secured without using a sealing material,
The boundary between the small-diameter portion and the annular slope portion is located at the same height as the upper end of the header, or higher.
The gas generator, wherein the igniter collar is disposed so as to surround a welded portion between the cup-shaped case and the header.   The substantially cylindrical igniter collar includes a lower annular wall portion that accommodates the conductive pin, an upper cylindrical wall portion that surrounds the header, and a space between the lower cylindrical wall portion and the upper cylindrical wall portion. An inwardly extending flange portion, and the upper cylindrical wall portion faces the side surface of the header and a part of the inward flange portion faces the bottom surface of the header on the conductive pin side. The gas generator according to claim 1.   The cup-shaped case includes a small-diameter portion located on the opening side, a large-diameter portion located on the bottom surface side, and an annular flat portion between the small-diameter portion and the large-diameter portion, and the small-diameter portion and the annular shape 3. The gas generator according to claim 1, wherein the height position in the axial direction of the boundary portion between the flat portion and the boundary portion between the large diameter portion and the annular flat portion is the same.   The gas generator according to any one of claims 1 to 3, wherein a surface of the cup-shaped case is covered with a resin.   The gas generator according to any one of claims 1 to 4, which is a gas generator for a seat belt pretensioner.

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