JP2007091082A - Gas generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator for an air bag with a good pressurized gas discharging property. <P>SOLUTION: A tip end 24c of a rod 24 for breaking a second rupture disc 28 is shaped like a disc. An outside diameter B<SB>1</SB>and an inside diameter A of a second passage 44 satisfies the relationship of 1/2A≤B<SB>1</SB><A, and the diameter of a rod center 24b is sufficiently smaller than the diameter B<SB>1</SB>. When the second rupture disc 48 is punched into a circular shape at a rod tip 24c, so as to open a gas flow path, and discharge of the gas is started, the diameter of the center 24b is small, so that resistance blocking a gas flow can be restrained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas generator used in a vehicle personnel restraint device.

  In a gas generator for inflating an air bag in a vehicle occupant restraint device or a pedestrian protection device, an ignition lead wire that obstructs the bag connection is connected in the vicinity of the gas exhaust port in order to connect the airbag to the gas exhaust port. A structure without an igniter or the like is preferable.

  Patent Document 1 discloses a gas generator using pressurized gas, in which an igniter and a gas discharge port are separated from each other. In a gas generator that uses pressurized gas, a rupture plate that serves as a closing means is used to close the gas discharge port. However, during operation, the rupture plate must be cleaved to open the gas discharge path. In Patent Document 1, a structure is employed in which a rupturable plate is cleaved by a rod operated by a high-temperature and high-pressure gas generated by the operation of an ignition means.

  In the invention of Patent Document 1, a seal 80 is integrally formed on the wall 14, and fragile portions having V-shaped grooves 82 and 84 are formed. The rod 74 is moved by the operation of the squib 44 and the gas generating agent 34 to break the seal from the V-shaped grooves 82 and 84. Therefore, in the gas generator having such a structure, it is necessary to form a V-shaped groove in order to reliably cleave the seal.

USP 3,856,180 specification

  In the gas generator of Patent Document 1, it is necessary to form the V-shaped grooves 82 and 84, and manufacturing and parts processing are complicated, which causes an increase in cost. In addition, since it is necessary to strictly manage the depth and width of the V-shaped grooves 82 and 84 in order to cleave the seal, the management of parts becomes complicated from the viewpoint of quality assurance.

  The present invention is a gas generator which is provided at a position where an igniter and a gas discharge port are separated from each other, and has a structure in which a blocking means of a gas discharge path to the gas discharge port is broken by a rod, and the blocking means is reliably cleaved An object of the present invention is to provide a gas generator capable of discharging gas and inflating an airbag.

As a means for solving the problems, the present invention
A cylindrical housing having two openings, an ignition means chamber connected to one opening of the cylindrical housing, and a diffuser part having a gas discharge port connected to the other opening of the cylindrical housing And
Between the cylindrical housing and the ignition means chamber is closed by a first closing means, and between the cylindrical housing and the diffuser part is closed by a second closing means, and a pressurized gas is contained in the cylindrical housing. Is filled,
In the cylindrical housing, a rod for destroying the second closing means and opening the passage to the diffuser part in operation, the root part is opposed to the first closing means, and the tip part is second closed. Arranged opposite the means,
The rod includes a tip portion having a flat surface facing the second closing means, and a center portion excluding the tip portion and the root portion, and the outer diameter of the tip portion is larger than the outer diameter of the center portion. Provided is a gas generator.

During operation of the gas generator, the first closing means is broken by the ignition means and the rod is propelled, the second closing means is broken by the rod, and the gas discharge path to the gas discharge port is opened, The airbag is inflated. In such an operation,
Requirement (a) that the second closing means is reliably destroyed,
Requirement (b) After the second blocking means is destroyed, two important points are that the pressurized gas is discharged instantly without generating a resistance that hinders the gas flow in the gas flow path. .

  When the pressurized gas is discharged from the gas generator, a portion of the gas flow path formed inside the gas generator becomes a resistance to the flow, and the resistance is reduced as the cross-sectional area of the gas flow path becomes smaller. growing. For this reason, it is conceivable to use a rod with a large outer diameter and destroy the second closing means with as large an area as possible. However, after the destruction of the second closing means, the rod itself narrows the gas flow path to increase the resistance. It can be generated. In such a case, both the above requirements (a) and (b) cannot be satisfied.

  In the present invention, as the rod for destroying the second closing means, a rod having a root portion, a center portion, and a tip portion having a flat surface and having an outer diameter of the tip portion larger than the outer diameter of the center portion is used. For this reason, since the second closing means is destroyed by the shearing force caused by the collision of the rod tip surface, the cleavage state of the second closing means is always constant regardless of the operating environment of the gas generator, and the center of the rod Since the outer diameter of the portion is small, it is possible to suppress the occurrence of resistance that obstructs the gas flow by narrowing the gas flow path. Further, by making the central portion thinner, the entire rod is lightened and is easily propelled by the ignition means.

  The cross-sectional shape of the center part and the tip part of the rod is preferably circular, but may be polygonal. Further, the central portion and the distal end portion are formed by separate members, and in addition to joining the two at the time of assembly, both can be formed integrally.

  The distal end portion (expanded diameter portion) and the center portion (reduced diameter portion) of the rod may be formed so that the outer diameter is discontinuous or may be continuously changed.

  The cylindrical housing has a cylindrical outer shape, but the position of the two openings is not limited, and the two openings may be provided at both ends, or may be provided on the peripheral surface, You may be provided in the edge part and the surrounding surface.

  The first closing means and the second closing means only need to be able to withstand the pressure in the cylindrical housing and maintain an airtight state. A rupturable plate made of a disc such as stainless steel used in a hybrid type gas generator or the like is used. Can be used.

In another aspect of the present invention, the second closing means closes a gas flow path formed between the cylindrical housing and the diffuser portion, and the tip end surface of the rod 2. The gas generator according to claim 1, wherein a relationship between an outer diameter (B ₁ ) and a diameter (A) of the gas flow path is 1 / 2A ≦ B ₁ <A.

By satisfying the relationship between the outer diameter (B ₁ ) of the end surface of the rod and the diameter (A) of the gas flow path within the above range, the requirement (a) can be easily satisfied.

The second closing means is punched into a shape substantially the same as the shape of the tip of the rod by the shearing force, the central portion is pulled out as one lump, and the other peripheral portions do not fall off. Thereafter, the dropped central portion is held in a state of being sandwiched between the rod tip portion and the inner surface of the diffuser portion. Therefore, if B ₁ and A are in the relationship of the above formula, the dropped central portion is the gas flow path. Will not block.

The rod is arranged such that the center of the rod tip and the center of the second closing means are on the same line. The outer diameter (B ₁ ) of the tip end face of the rod (or the length between opposing vertices if the tip end face is polygonal) is 75% or more and less than 100% of the cross-sectional diameter (A) of the gas flow path. It is preferable that

  In addition, when the rod moves, the tip of the rod can be tapered so as not to affect the movement of the tip even if the tip contacts the gas flow path.

In another aspect of the present invention, the relationship between the outer diameter (B ₂ ) of the central portion of the rod and the diameter (A) of the gas flow path is B ₂ ≦ 1 / 2A. A gas generator according to claim 2 is provided.

By setting the relationship between the outer diameter (B ₂ ) of the rod center portion and the diameter (A) of the gas flow path within the above range, the above requirement (b) can be easily satisfied.

  In another aspect of the present invention, the diffuser portion has a cup shape having a plurality of gas discharge ports in a peripheral wall portion, and the second end closing means is broken by the rod, and then the tip end surface. The gas generator according to claim 1, wherein the gas generator is brought into contact with a bottom surface of the diffuser portion so as not to block the gas discharge port.

  When the rod tip passes through the central portion of the second closing means and reaches the diffuser portion, the central portion that has fallen off is sandwiched and held between the rod tip portion surface and the closed end surface (diffuser portion bottom surface). Moreover, since the rod tip is flat, when the rod tip collides against the bottom surface of the diffuser, the force is dispersed so that the rod does not penetrate. Therefore, it is not necessary to increase the thickness of the bottom surface of the diffuser part, and the parts can be easily processed.

  Further, among the plurality of gas discharge ports formed in the peripheral wall portion of the diffuser portion, the gas discharge port formed in the vicinity of the closed end surface is formed away from the closed bottom surface by at least the thickness of the rod tip portion. Even when the rod tip surface comes into contact with the bottom surface of the diffuser portion, all of the gas discharge ports in the peripheral wall portion of the diffuser can be opened.

  This invention provides the gas generator in any one of Claims 1-4 which has the groove | channel by which the said rod center part becomes a gas flow path as another solution means of a subject.

  Thus, by forming the groove | channel used as a gas flow path in a rod center part, a gas flow is not inhibited and the above-mentioned requirement (b) is satisfied easily.

The groove may be a continuous groove from the rod root part to the rod tip part or a discontinuous groove as long as it does not inhibit the gas flow. The groove may be one or a plurality of grooves, may be a spiral groove, or may be a linear groove.
When the groove is formed in this way, when the cross section in the diametrical direction is viewed, a plurality of irregularities are formed in the circumferential direction, of which the concave portion becomes a gas flow path and the convex portion reinforces the rod. Because of the function of the ribs, deformation such as deflection is prevented even when the rod is lengthened.
The groove may be formed in the entire region of the center portion of the rod or may be formed in a part. When forming in a part, it forms in the part located in the channel | path to a diffuser part after the movement of a rod.

  According to the present invention, as another means for solving the problem, an area of a surface of the rod root portion facing the first closing means is larger than a cross-sectional area of the rod center portion. A gas generator as described is provided.

  Since the rod root part is a part that receives combustion products such as shock waves and pressure waves generated from the ignition means (electric igniter), the rod root part surface is formed to have a larger diameter than the center part. preferable.

  According to the gas generator of the present invention, the second closing means is surely destroyed in a large area and the gas flow path is released, and after the second closing means is destroyed, the pressurized gas is discharged instantaneously, The airbag is inflated.

(1) Gas Generator in FIGS. 1 and 2 The gas generator in FIG. 1 is a stored type that uses pressurized gas as inflation means for an airbag. 1 is a sectional view in the axial direction, and FIG. 2 is a partially enlarged view of FIG.

  The cylindrical housing 20 has two openings on both ends, and has an ignition means chamber 30 connected to the opening on one end side, and a diffuser section 40 connected to the opening on the other end side. is doing. These are made of stainless steel or aluminum, and are fixed by welding at the respective joints.

  The interior space 22 of the cylindrical housing 20 is kept airtight and is filled with a simple substance such as argon, helium, nitrogen, or a mixed gas thereof (filling pressure is about 35,000 to 70,000 kPa). The pressurized gas preferably has a sound velocity of 400 m / sec or more at 0 ° C. and 1 atm (101.325 kPa). After the pressurized gas is filled from the filling hole, it is blocked by the pin 23. The pin 23 is welded to the cylindrical housing 20.

  The ignition means chamber 30 has an outer shell formed by an ignition means chamber housing 32. Inside the ignition means chamber housing 32, an electric igniter 36 provided with an igniting agent is accommodated. The igniter 36 is connected to a vehicle power supply circuit via a connector and a lead wire (both not shown). As the igniter 36, an igniter containing 260 mg of an ignition agent mainly composed of zirconium and potassium perchlorate is used.

  The first passage 37 between the cylindrical housing 20 (internal space 22) and the ignition means chamber 30 is closed by a stainless steel first rupturable plate 38, and the inside of the ignition means chamber 30 is at normal pressure. . The peripheral edge of the first rupturable plate 38 is welded and fixed to a first annular stepped surface 33 provided on the inner surface of the ignition means chamber housing 32.

  The diffuser section 40 has an outer shell formed by a diffuser housing 42, and the diffuser housing 42 is provided with a plurality of gas discharge ports 46 that discharge pressurized gas to the outside.

  The second passage 44 between the cylindrical housing 20 (internal space 22) and the diffuser portion 40 is closed with a second rupturable plate 48 made of stainless steel, and the inside of the diffuser portion 40 is at normal pressure. The peripheral edge of the second rupturable plate 48 is fixed to the diffuser housing 42 by welding.

  A rod 24 for cleaving the second rupturable plate 48 is disposed in the cylindrical housing 20. The rod 24 is composed of a disc-shaped root portion 24a, a center portion (shaft portion) 24b, and a tip portion 24c. The respective portions are integrated and are made of metal such as stainless steel or aluminum. Of the rod tip 24c, the side facing the second rupturable plate 48 is disc-shaped.

  The base portion 24 a of the rod is in contact with a second annular step surface 34 provided on the inner surface of the ignition means chamber housing 32. In FIG. 1, the first rupturable plate 38 and the root portion 24 a are separate members. However, the root portion 24 a and the first rupturable plate 38 may be formed integrally, and the root portion 24 a further includes the first rupturable plate 38. It may be something that doubles as well.

  The retainer 50 is fitted (or press-fitted) in a state of being in contact with the inner wall surface 21 of the cylindrical housing 20 and the diffuser housing 42, and further holds a portion of the central portion 24b of the rod 24 that is close to the tip portion 24c. .

  In this manner, the rod 24 is fixed at a predetermined position by the retainer 50 and the ignition means chamber housing 32, and rattling of the rod 24 due to external vibration or the like is prevented.

The rod 24 is opposed to the second rupturable plate 48 that closes the cylindrical housing 20 and the second passage 44 in a state where the distal end portion 24c of the rod 24 is separated. The second passage 44 becomes a gas flow path, and its inner diameter (A) is larger than the outer diameter (B ₁ ) of the tip end face of the rod tip 24c. In FIG. 2, B ₁ is 90% larger than A. Is set.

  The retainer 50 is fitted into the cylindrical housing 20 and fixes the rod 24 so that the center of the distal end surface 24d of the rod distal end 24c is collinear with the center of the second passage 44.

  A peripheral portion 51 of the retainer 50 is in contact with the diffuser housing 42, and a peripheral surface portion 52 is in contact with the inner wall surface 21 of the cylindrical housing 20.

  Next, the operation when the gas generator 10 shown in FIGS. 1 and 2 is incorporated into an automobile airbag system will be described. In the gas generator 10, the igniter 36 for pulling out the lead wire and the gas discharge port 46 for attaching the airbag are located on the opposite side, so that the lead wire does not get in the way when the airbag is attached.

  When the automobile collides and receives an impact, the first rupturable plate 38 is destroyed by the shock wave and pressure wave generated by receiving the operation signal from the control unit and the igniter 36 being activated and ignited. Opened. The shock wave or pressure wave that broke the first passage 37 subsequently collides with the rod disk part (root part) 24a and presses the rod 24 toward the second rupturable plate 48 side.

As a result, the rod 24 moves in the axial direction, the tip 24c of the rod tip 24c collides with the second rupturable plate 48, and the second rupturable plate 48 has substantially the same shape as the tip end surface 24d by shearing force. It is punched and dropped off, and is sandwiched between the tip end face 24d and the bottom face 53 of the diffuser part 40. At this time, if the relationship between the thickness C of the tip 24c and the distance D between the gas outlet 46 formed in the diffuser 40 and the outlet closest to the diffuser bottom surface 53 is D> C, the rod 24 Even after the gas has moved, the gas outlet 46 is not blocked.
In addition, you may provide the fixing means which prevents that the rod 24 moves after an action | operation (it maintains the state which the front-end | tip part 24c and the diffuser bottom face 53 contacted) as needed.

  In order to suppress interference between the rod tip 24c and the corner 40a of the diffuser 40 that forms the second passage 44 during the movement of the rod 24, the rod tip 24c may be tapered.

(2) Gas Generator of FIG. 3 FIG. 3 is a gas generator of a different form from FIG. FIG. 3 is a partial cross-sectional view in the axial direction. 3 and 1 differ only in the rod and the retainer.

  The rod 54 in FIG. 3 has a root portion (not shown), a center portion 54b, a tip portion 54c, and a tip portion surface 54d in the same manner as the rod 24 in FIG. Has a spiral groove (wood screw-like groove) 54e. The concave portion of the groove 54e becomes a gas flow path, and the convex portion becomes a reinforcing portion.

  The rod tip end face 54 d is circular, and its outer diameter is 90% of the inner diameter of the second passage 44. The diameter between the convex parts of the center part 54b is equal to or less than the diameter of the rod tip part surface 54d.

  The retainer 50 has a folded flange 50a so that the outer peripheral surface of the rod tip 54c can be held in a wider range.

(3) Gas Generator in FIG. 4 FIG. 4 is a gas generator having a different form from that in FIG. FIG. 4 is a partial cross-sectional view in the axial direction. 4 and 1 differ only in the rod and the retainer.

  The rod 64 in FIG. 4 has a root portion (not shown), a center portion 64b, a tip portion 64c, and a tip portion surface 64d, as in the rod 24 in FIG. Has a spiral groove (drill-like groove) 64e. The concave portion of the groove 64e serves as a gas flow path, and the convex portion serves as a reinforcing portion.

  The rod tip end face 64 d is circular, and its outer diameter is 90% of the inner diameter of the second passage 44. The diameter between the convex parts of the center part 64b is equal to or less than the diameter of the rod tip part surface 64d.

  The retainer 50 has a folded flange 50a so that the outer peripheral surface of the rod tip 64c can be held in a wider range.

The longitudinal cross-sectional view of a gas generator. The elements on larger scale of the gas generator of FIG. The longitudinal cross-sectional view of the gas generator using the rod of another form. Furthermore, the longitudinal cross-sectional view of the gas generator using the rod of another form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Gas generator 20 Cylindrical housing 24 Rod 30 Ignition means chamber 32 Ignition means chamber housing 38 1st rupturable plate 40 Diffuser part 42 Diffuser housing 46 Gas discharge port 48 2nd rupturable plate 50 Retainer

Claims (6)

A cylindrical housing having two openings, an ignition means chamber connected to one opening of the cylindrical housing, and a diffuser portion having a gas discharge port connected to the other opening of the cylindrical housing And
Between the cylindrical housing and the ignition means chamber is closed by a first closing means, and between the cylindrical housing and the diffuser part is closed by a second closing means, and a pressurized gas is contained in the cylindrical housing. Is filled,
In the cylindrical housing, a rod for destroying the second closing means and opening the passage to the diffuser part in operation, the root part is opposed to the first closing means, and the tip part is second closed. Arranged opposite the means,
The rod includes a tip portion having a flat surface facing the second closing means, and a center portion excluding the tip portion and the root portion, and the outer diameter of the tip portion is larger than the outer diameter of the center portion. Gas generator that is. The second closing means closes a gas flow path formed between the cylindrical housing and the diffuser portion, and the outer diameter (B ₁ ) of the end surface of the rod and the gas flow path The gas generator according to claim ₁ , wherein the relationship with the diameter (A) is ½A ≦ B ₁ <A. The gas generator according to claim 1 or 2, wherein a relationship between an outer diameter (B ₂ ) of the central portion of the rod and a diameter (A) of the gas flow path is B ₂ ≤ 1 / 2A.   The diffuser portion has a cup shape having a plurality of gas discharge ports in a peripheral wall portion, and the diffuser portion prevents the tip end surface from closing the gas discharge port after the second blocking means is broken by the rod. The gas generator in any one of Claims 1-3 contact | abutted by the bottom face of a part.   The gas generator according to any one of claims 1 to 4, wherein the rod central portion has a groove serving as a gas flow path. The gas generator according to any one of claims 1 to 5, wherein an area of a surface of the rod base portion facing the first closing means is larger than a cross-sectional area of the rod center portion.

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