JP2006218990A - Gas generator for occupant restraint system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator for an occupant restraint system capable of enhancing the pressure resistance and the fracture resistance of a closing member forming a sealing means of pressurized gas. <P>SOLUTION: A first closing member 40 which is one means to seal gas in a pressurized gas chamber 20 is protruded into the pressurized gas chamber 20 side against the gas pressure. Thus, the first closing member has excellent pressure resistance against the gas pressure, and easily fracture compared with a conventional case in which the member is protruded to the opposite side under the gas pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas generator for an occupant restraint device used in an automobile airbag system.

  A gas generator that uses pressurized gas uses a rupturable plate for enclosing the pressurized gas inside a pressurized bottle (pressurized housing). The rupture plate is ruptured by a shock wave generated by an igniter or a pressure increase caused by combustion of the gas generating agent to form an opening, and pressurized gas inside the housing (in some cases, the combustion gas of the gas generating agent) Drain outside the housing.

As a requirement for a gas generator using such a bursting plate,
(A) the rupture disc must rupture at a predetermined pressure;
(B) that the fragments of the rupturable plate are not discharged outside the housing;
(C) The structure of the entire gas generator is simple,
Is required.

  Patent Document 1 discloses a gas generator using pressurized gas. The housing 622 is filled with pressurized gas, and a gas generator housing 644 is disposed inside the housing 622 along with an igniter 648 at one end of the housing 622. A propellant 646 is arranged inside the gas generator housing 644 and communicates with the inside of the housing 622 through a port 650, but before operation, the port 650 is closed by the first disk 652. ing.

The disk 652 is originally a thin plate, but is deformed into a bowl shape in the gas generator housing 644 in response to the pressure of the pressurized medium filled in the housing 622. Similarly, the gas outlet formed at the opposite end of the housing 633 is also closed by a second disk that is deformed into a bowl shape under the pressure of the pressurized medium.
USP 5,821,448

  When a thin plate-like member is used as the closing means as in Patent Document 1, it receives a pressurized gas pressure and protrudes in a bowl shape in the opposite direction (the opposite direction to the housing 622 filled with the pressurized gas). It transforms into a state. In this state, when the closure means projecting in a bowl shape is to be cleaved, a pressure higher than the accumulated pressure of the pressurized gas is applied to the rupturable plate, the rupturable plate is once deformed toward the inside of the housing 622, and then it is cleaved by a tensile force. become.

  Further, the closing member must sufficiently withstand the pressure of the pressurized gas accumulated in the housing 622, and at the same time, needs to be quickly broken when a predetermined pressure is applied. Therefore, in order to rupture with good reproducibility, it is necessary to strictly manage conditions such as the thickness, diameter, nozzle diameter, and tensile strength of the rupture disc.

  The present invention satisfies the above-mentioned requirements (a) to (c), and can ease the burden during production by relaxing the management conditions such as the dimensions and physical properties of the rupturable plate, and can achieve reduction in production cost. It is an object to provide a gas generator for an occupant restraint device.

  The gas generator for an occupant restraint device of the present invention is mounted on a vehicle and restrains the vehicle occupant such as an inflating gas generator for protecting an occupant from an impact or a gas generator for operating a seat belt pulling mechanism. Can generally be used in the device. Below, the case where it uses for an airbag system mainly is demonstrated.

As a means for solving the problems, the present invention
A gas generator for an occupant restraint device having a pressurized gas chamber filled with a pressurized gas and a gas generating chamber connected to the pressurized gas chamber and having a gas discharge port for discharging the pressurized gas. ,
A gas generator for an occupant restraint device is provided in which a first communication path between the pressurized gas chamber and the gas generating chamber is closed by a first closing means protruding toward the pressurized gas chamber.

  The pressurized gas chamber is filled with pressurized gas, which serves as an inflation medium for the airbag, at a high pressure, and the first closing member protrudes toward the pressurized gas chamber against this high pressure. is there. For this reason, compared with a blocking member deformed by being pressed by pressure as in the disk 652 in Patent Document 1, the pressure resistance against pressurized gas is high, and it is easy to be cleaved by a force applied from the side opposite to the protruding side. ing.

  Such a property utilizes the compressive strength and tensile strength of the member used for the first closing means. Specifically, the compressive strength is usually higher than the tensile strength under the same conditions. Is used. Therefore, the pressure resistance to the pressurized gas is improved by the compressive strength of the first closing member, and when the gas generator is operated, a force less than the compressive strength and higher than the tensile strength is applied from the gas generating chamber side to the first closing member. Is to cleave.

  The gas generation chamber referred to in the present invention refers to both a solid gas generating agent that generates gas by combustion, an igniter that ignites and burns the solid gas generating agent, or an igniter only. Therefore, in the gas generation chamber, the pressure in the gas generation chamber is increased by gas or heat from the gas generating agent, or a shock wave is directly generated by the igniter, so that the first rupturable plate is cleaved to the pressurized gas chamber side. It works to let you.

  As described above, the gas generator of the present invention utilizes the tensile strength and the compressive strength by forming the first closing member in a shape protruding to the pressurized gas chamber side. There is no need to strictly manage physical properties. For this reason, the cost concerning components can be reduced, the manufacturing method and the structure itself can be simplified, and the manufacturing cost can be reduced.

  In another aspect of the present invention, the gas discharge port is disposed on the opposite side of the pressurized gas chamber from the gas generation chamber, and is provided between the pressurized gas chamber and the gas discharge port. The occupant restraint device gas generator according to claim 1, wherein the second communication passage is closed by a second closing means.

  By doing in this way, when attaching an airbag to a gas exhaust port, the lead wire extended from the igniter does not interfere with the airbag and does not impair attachment workability.

  In another aspect of the present invention, the first closing member has a bottom surface and a side surface, and is fixed to the other member at the periphery of the opening facing the bottom surface, or hemispherical. Then, the gas generator for an occupant restraint device according to claim 1, which is fixed to another member at the periphery of the opening.

  The bottom surface and the side surface are preferably integrally formed, and the thickness may be the same or different. The shape of the bottom surface may be a triangle, a quadrangle (rectangle, square), a pentagon or more polygon, and any other shape, and the side surface may be a vertical wall surface or an inclined surface. Further, the boundary portion (corner portion) between the bottom surface and the side surface may be rounded.

  The first closing member can have a hollow cylindrical shape, a hollow conical shape (however, the top portion is a flat surface), a hollow prismatic shape (both whose corner portions are rounded), and the like as described above. It can be hemispherical (dome-shaped). Furthermore, the periphery of the opening part of the first closing member may have a flange part extending outward in the radial direction, and the flange part may be fixed to another member.

  The present invention provides the gas generator for an occupant restraint device according to any one of claims 1 to 3, wherein the first closing member has a weakened portion at least partially as another means for solving the problem. provide.

  The fragile part is a part formed so as to be preferentially destroyed when the gas generator is operated. Such a weak part can be formed by reducing the thickness or scratching, and can be formed continuously or discontinuously in part or all of the first closing member. . By providing such a fragile portion, the first closing member can be surely destroyed during operation of the gas generator, and the first closing member can be crushed or become a large number of small pieces. To prevent splashing.

  The present invention provides the occupant restraint device according to any one of claims 1 to 3, wherein, as another means for solving the problem, the first closing member has a fragile portion in a part near the periphery of the opening. A gas generator is provided.

  By destroying at a part near the periphery of the opening, it is possible to sufficiently withstand the pressure of the pressurized gas, and to preferentially cleave from the fragile part at the time of cleavage. In addition, the first closing member is partially connected to the periphery of the opening even after the cleavage, so that the dropped first closing member is prevented from entering the pressurized gas chamber.

  In another aspect of the present invention, the pressurized gas chamber has an outer shell formed by a pressurized gas chamber housing, the gas generating chamber has an outer shell formed by the gas generating chamber housing, The occupant restraint device gas generator according to any one of claims 1 to 5, wherein one closing member is formed integrally with the gas generation chamber housing.

  By molding integrally with the gas generation chamber housing, the parts cost can be reduced and the manufacturing process can be simplified.

  In another aspect of the present invention, the first closing member is attached so as to close the first communication path from the pressurized gas chamber side and be detachable from the pressurized gas chamber side. The gas generator for an occupant restraint device according to claim 1 or 2, wherein the gas generator is a flat plate that does not substantially deform with respect to a gas filling pressure.

  The flat plate used as the first closing member has a strength that does not substantially deform with respect to the filling pressure of the pressurized gas (although it is adjusted depending on the thickness and material, but is mainly the thickness). The thickness is larger than the flat burst plate of the gas generator using the pressurized gas, and the gas generator protrudes toward the pressurized gas chamber at the time of attachment. By using such a flat plate, the material management as the closing member is facilitated, so that the cost can be reduced.

  The gas generator for an occupant restraint device according to the present invention has a shape in which two closing means protrude against the pressure of the pressurized gas, unlike the conventional one using pressurized gas.

  For this reason, the pressure resistance and destructibility of the first closing means are improved. Furthermore, since it is no longer necessary to strictly manage dimensions and physical properties as in the case of a conventional closing member, the cost of parts can be reduced, and the manufacturing method and structure itself can be simplified, thereby reducing the manufacturing cost. It becomes possible.

(1) Gas generator of FIG. 1 The gas generator of the present invention will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

  The gas generator 10 includes a pressurized gas chamber 20, a gas generation chamber 30, and a diffuser portion 50, and the outer diameters thereof are set to be substantially the same.

  The pressurized gas chamber 20 has an outer shell formed by a cylindrical pressurized gas chamber housing 22, is made of a mixture of argon and helium, and is filled with a pressurized gas that does not contain oxygen gas (filling pressure is About 30,000-67,000 kPa).

  The pressurized gas chamber housing 22 is symmetrical with respect to the axial direction and the radial direction. The length L of the pressurized gas housing 22 is set to about 50 to 250 mm, and L / D is 1 to 10.

  Since the pressurized gas chamber housing 22 has such a shape, it is not necessary to adjust the orientation in the axial direction and the radial direction at the time of assembly, and the gas generating chamber 30 and the diffuser portion 50 are joined by resistance welding or the like. Work becomes easy.

  A pressurized gas filling hole 24 is formed in a side surface of the pressurized gas chamber housing 22 and is closed by a pin 26 after being filled with the pressurized gas. The tip portion 26a of the pin 26 protrudes into the pressurized gas chamber 20, and the protruding portion has a length with which the combustion gas flow of the gas generating agent collides. By adjusting the length of the protruding portion of the pin 26, the combustion gas can collide with the pin 26 itself, and the combustion residue can be adhered. In FIG. 1, it can extend until the front-end | tip part 26a of the pin 26 contact | abuts to the opposing inner wall face 22a.

  The gas generation chamber 30 has an outer shell formed by a gas generation chamber housing 32, includes ignition means (electric igniter) 34 and a gas generating agent 36, and is joined to one end side of the pressurized gas chamber 20. Has been. The igniter 34 is fixed by caulking a part 35 of the gas generator housing 32.

  The gas generating agent 36 has a cylindrical shape so that an operating portion (a portion that includes an ignition agent and is cleaved during operation to generate a combustion product) 34a is inserted into the inner hole. Has been placed.

The gas generating agent 36 is nitroguanidine / strontium nitrate / carboxymethylcellulose sodium salt / acid clay = 34.3 / 49.6 / 9.4 / 6.7 (mass%) (pressure index = 0.6, combustion flame temperature) = 1.98-5.3 g of the product consisting of = 2098 ° C). The ratio between the amount of pressurized gas (number of moles) (A ₁ ) and the amount of gas (number of moles) generated by combustion of the gas generating agent (A ₂ ) is A ₁ / A ₂ = 1-20.

  The gas generation chamber housing 32 and the pressurized gas chamber housing 22 are resistance-welded at the joint 49. When the gas generator 10 is incorporated in an airbag system, the igniter 34 is connected to an external power source via a connector and a lead wire.

  The first communication hole 38 between the pressurized gas chamber 20 and the gas generation chamber 30 is closed by a first closing member 40 protruding toward the pressurized gas chamber 20, and the inside of the gas generation chamber 30 is kept at normal pressure. Is retained.

  The first closing member 40 is formed integrally with the gas generator housing 32, has a circular bottom surface 41 and a side surface 42, and an opening peripheral edge facing the bottom surface 41 is integrated with the gas generator housing 32. Yes. The boundary portion between the bottom surface 41 and the side surface 42 is rounded.

  The first closing member 40 has a fragile portion 45 at a part of the peripheral edge of the lower end portion of the side surface 42 (periphery of the opening facing the bottom surface 41). The fragile portion 45 is obtained by reducing the thickness of the portion corresponding to the periphery of the opening of the first closing member 40, and is provided continuously or discontinuously over a range of 50 to 100% of the entire periphery of the opening. ing.

  Thus, the first closing member 40 protrudes against the pressure of the pressurized gas inside the pressurized gas chamber 20, and the force received by the bottom surface 41 and the side surface 42 becomes the compressive force of the entire first closing member 40. . The compression force of the member is larger than the tensile force under the same conditions, and has sufficient pressure resistance against the pressure of the pressurized gas.

  The other end side of the pressurized gas chamber 20 is connected to a diffuser portion 50 having a gas discharge port 52 for discharging the pressurized gas and the combustion gas, and the diffuser portion 50 and the pressurized gas chamber housing 22 are connected to each other. Resistance welding is performed at 54. In the diffuser unit 50, a filter such as a wire mesh can be arranged as necessary in order to capture combustion residues.

  The second communication hole 56 between the pressurized gas chamber 20 and the diffuser part 50 is closed by a second closing member 58 that is deformed like a bowl by the pressure of the pressurized gas, and the diffuser part 50 is kept at normal pressure. Is retained. The second closing member 58 is resistance welded to the diffuser portion 50 at the peripheral edge portion 59.

  Next, the operation when the gas generator 10 shown in FIG. 1 is incorporated in an airbag system mounted on an automobile will be described.

  When the automobile collides and receives an impact, the activation signal is received from the control unit, and the igniter 34 is activated and ignited to burn the gas generating agent 36 to generate high-temperature combustion gas.

  As the pressure inside the gas generation chamber 30 rises, the first closing member 40 protruding into the pressurized gas chamber 20 is easily cleaved at the fragile portion 45. At this time, since the fragile portion 45 is formed only in a part of the first closing member 40, the portion where the fragile portion 45 is not formed remains in a state of being connected to the gas generation chamber housing 32 without being broken.

  For this reason, a part of the first closing member 40 is cleaved to communicate the gas generation chamber 30 and the pressurized gas chamber 20, but remains in a state of being connected to the gas generation chamber housing 32. Therefore, all or part of the first closing member 40 is separated and flows toward the gas discharge port 52, and the gas passage is not blocked.

  When the pressure in the pressurized gas chamber 20 rises due to the temperature rise caused by the inflow of the combustion gas accompanying the cleavage of the first closing member 40 and the additional gas from the combustion gas, the second closing member 58 is destroyed and the second closing member 58 is destroyed. The two communication paths 56 are opened. Thereafter, the pressurized gas and the combustion gas are discharged from the gas discharge port 52 through the second communication hole 56 to inflate the airbag.

  When the high-temperature combustion gas flows into the pressurized gas chamber 20, the temperature difference between the pressurized gas and the combustion gas in the pressurized gas chamber 20 is large, so that the combustion gas is rapidly cooled, and the high-temperature combustion residue is cooled and solidified. Is done. Further, the combustion gas collides with the pin 26, so that the combustion residue is also attached to the pin 26.

(2) Gas Generator in FIG. 2 FIG. 2 is a longitudinal sectional view of a gas generator according to another embodiment. Since the gas generator 100 of FIG. 2 has basically the same structure as the gas generator of FIG. 1, only different parts will be described. The same numbers as those in FIG. 1 mean the same thing.

  The first communication hole 38 between the pressurized gas chamber 20 and the gas generation chamber 30 is closed by a first closing member 60 protruding toward the pressurized gas chamber 20, and the inside of the gas generation chamber 30 is kept at normal pressure. Is retained.

  The first closing member 60 is hemispherical, and the periphery of the opening is formed integrally with the gas generator housing 32.

  The first closing member 60 has a fragile portion 45. The fragile portion 45 is obtained by reducing the thickness of the portion corresponding to the periphery of the opening of the first closing member 40, and is provided continuously or discontinuously over a range of 50 to 100% of the entire periphery of the opening. Yes.

  The gas generating chamber 30 is filled with a small particle (a desired shape such as a columnar shape or a disk shape) of the gas generating agent 70, and the gas generating agent 70 is disposed in contact with the operating portion 34 a of the igniter 34. Yes. In front of the first communication hole 38, a screen 72 formed of a metal mesh, punching metal or the like is disposed. The opening of the screen 72 is smaller than the size of the gas generating agent 70.

(3) Gas Generator in FIG. 3 FIG. 3 is a partial longitudinal sectional view of a gas generator according to another embodiment. Since the gas generator 200 of FIG. 3 has basically the same structure as the gas generator of FIG. 1 or the gas generator of FIG. 2, only different parts will be described.

  The first closing member 80 has a flat plate shape, and is attached from the pressurized gas chamber 20 side so as to close the first communication path 38. The disc-shaped first closing member 80 has a strength (thickness) that does not substantially deform even with respect to the filling pressure of the pressurized gas chamber 20, and therefore protrudes slightly toward the pressurized gas chamber 20 side. It is attached in the state. The thickness of the first closing member 80 is determined by comprehensively considering the diameter of the first communication passage 38, the material (tensile strength) of the first closing member 80, and the filling pressure of the pressurized gas.

  The disc-shaped first closing member 80 is fixed by welding to the gas generation chamber housing 32 forming the first communication passage 38 (welding portion 81), and the welding portion 81 is shown in FIG. It corresponds to the weak part of the gas generator in FIG. Therefore, when the gas generator 200 is operated, the first closing member 80 is peeled off and detached at the welded portion 81 to open the first communication path 38. In addition, by adjusting the welding strength of the welded portion 81, only a part of the welded portion 81 is used as a weakened portion, the remaining weld strength is increased, and the first communication passage 38 is opened, but the entire first closing member 80 is opened. Can also be prevented from desorbing.

  The first closing member 80 may be attached by an attachment method other than welding. For example, an annular protrusion is provided on the periphery of the opening of the first communication passage 38 of the gas generation chamber housing 32, and the first protrusion 80 is caulked by the annular protrusion. One closing member 80 may be attached. In this case, similarly to welding, a part (fragile part) with weak caulking can be provided in part or all. In addition, the first closing member 80 can be caulked by the pressure from the gas generation chamber 30, and the entire caulked portion can be a weak portion.

  The gas generator of FIGS. 1 to 3 uses an igniter and a solid gas generating agent in combination as means for cleaving the first closing member, but the first closing member may be cleaved only by the igniter. Good.

  The gas generator of the present invention includes a gas generator for an airbag in a driver seat, a gas generator for an airbag in a passenger seat, a gas generator for a side airbag, a gas generator for a curtain, a gas generator for a knee bolster, and a gas It can be applied to various gas generators such as a generator for a bull seat belt, a gas generator for a tubular system, and a gas generator for a pretensioner.

The longitudinal cross-sectional view of the gas generator for passenger | crew restraint apparatuses. The longitudinal cross-sectional view of the gas generator for passenger | crew restraint apparatuses of another form. The fragmentary longitudinal cross-sectional view of the gas generator for passenger | crew restraint apparatuses of another form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 100 Gas generator 20 Pressurized gas chamber 22 Pressurized gas chamber housing 30 Gas generating chamber 32 Gas generating chamber housing 34 Igniter 38 First communication path 40 First closing member 50 Diffuser part 52 Gas discharge port 56 Second connection Passage 58 Second closing member

Claims (7)

A gas generator for an occupant restraint device having a pressurized gas chamber filled with a pressurized gas and a gas generating chamber connected to the pressurized gas chamber and having a gas discharge port for discharging the pressurized gas. ,
A gas generator for an occupant restraint device, wherein a first communication path between the pressurized gas chamber and the gas generating chamber is closed by a first closing means protruding toward the pressurized gas chamber.   The gas discharge port is disposed on the opposite side of the pressurized gas chamber from the gas generation chamber, and the second communication path between the pressurized gas chamber and the gas discharge port is closed by a second closing means. The gas generator for an occupant restraint device according to claim 1.   The first closing member has a bottom surface and a side surface, and is fixed to another member at the periphery of the opening facing the bottom surface, or is hemispherical and fixed to the other member at the periphery of the opening. The gas generator for an occupant restraint device according to claim 1 or 2, wherein the gas generator is used.   The occupant restraint device gas generator according to any one of claims 1 to 3, wherein the first closing member has a weakened portion at least in part.   The occupant restraint device gas generator according to any one of claims 1 to 3, wherein the first closing member has a fragile portion in a part near the periphery of the opening.   The pressurized gas chamber has an outer shell formed by a pressurized gas chamber housing, the gas generating chamber has an outer shell formed by a gas generating chamber housing, and the first closing member is integrated with the gas generating chamber housing. The gas generator for an occupant restraint device according to any one of claims 1 to 5, wherein The first closing member closes the first communication path from the pressurized gas chamber side and is attached so as to be detachable from the pressurized gas chamber side, and does not substantially deform with respect to the pressurized pressure of the pressurized gas. The gas generator for an occupant restraint device according to claim 1, wherein the gas generator is a flat plate.

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