JP5081850B2 - Inflator for airbag - Google Patents

Description

  The present invention relates to an inflator that generates gas to be supplied to an airbag installed in an automobile as a safety device.

  The airbag device protects an occupant from an impact at the time of collision by deploying the airbag with gas generated by an inflator.

  FIG. 7 is a cross-sectional view for explaining an example of the structure of the single-stage type inflator 1 and is configured as follows, for example. 2 is a pressure vessel composed of a diffuser 2a, an adapter 2b, and a base 2c. An igniter 3 that is activated by a collision detection signal, an igniter 4 that instantaneously amplifies the ignition energy of the igniter 3, and a large amount of gas are instantaneously generated. The gas generating agent 5 is built in.

  At the time of collision, the gas generating agent 5 is ignited by the igniter 3 through the igniting agent 4, and the generated gas is ejected from the gas ejection hole 2aa provided in the side wall of the diffuser 2a to deploy the airbag. At that time, collection of solid residue contained in the gas and cooling of the gas are performed by the filter 6 disposed along the inner peripheral side of the side wall of the pressure vessel 2 (Patent Document 1).

  Reference numeral 7 in FIG. 7 denotes an inner lid that prevents the gas generating agent 4 from spilling when the diffuser 2a is joined to the base 2c and prevents gas from leaking from the upper end of the filter 6 when the inflator 1 is operated.

JP-A-10-29493

  Since the inside of the pressure vessel 2 constituting the inflator 1 becomes a high pressure when gas is generated, a material and a shape having a strength capable of withstanding the high pressure are required.

  By the way, the diffuser 2a and the base 2c constituting the pressure vessel 2 are joined by friction welding, and the adapter 2b and the base 2c are joined by electric resistance welding. FIG. 10 shows an enlarged view of the periphery of an electric resistance welded portion (hereinafter referred to as a joint portion) Y2 between the adapter 2b and the base 2c. A space 2d having a substantially square cross section surrounded by the adapter 2b and the base 2c is provided so that a part of the material melted during the electric resistance welding escapes and stays in the space 2d. . The space 2d is necessary for preventing the melted material from scattering inside the inflator and entering the inside of the inflator as a foreign object.

  When the internal pressure of the pressure vessel 2 increases due to the generation of gas, the diffuser 2a and the base 2c expand from the shape before the gas generation shown in FIG. 8A, as shown in FIG. 8B. It has been found that if an inflator gas having a pressure higher than that of the conventional type is generated, there is a possibility of explosion.

  As a result of the inventors' investigation, the breakage point S when the pressure vessel 2 breaks is not the junction Y1 between the diffuser 2a and the base 2c or the junction Y2 between the adapter 2b and the base 2c, but the junction between the adapter 2b and the base 2c. It was found that the vicinity of the outer peripheral portion of the portion Y2 (see FIG. 9).

  That is, in the case of the conventional pressure vessel 2, when the expansion pressure of gas higher than the conventional pressure vessel is applied from the inside of the pressure vessel 2, the contact portion C near the outer peripheral portion of the joint portion Y2 between the adapter 2b and the base 2c serves as a fulcrum. The base 2c is deformed as shown by a two-dot chain line in FIG. It is presumed that stress concentrates on this deformed portion and breaks.

  When the pressure vessel breaks, the gas flows out from the breakage point and the amount of gas ejected from the gas ejection hole of the inflator is reduced, so that the performance required by the airbag cannot be fully exhibited.

  The problem to be solved by the present invention is that, in the case of a conventional inflator, when the internal pressure rises at the time of gas generation, the contact portion near the outer peripheral portion of the joint portion between the adapter and the base becomes a fulcrum, and the base is deformed. It is a point that stress concentrates on the deformed portion and may break.

The inflator for an airbag of the present invention is
To prevent the pressure vessel from breaking even if the internal pressure rises when gas is generated,
Inside the pressure vessel that joins and integrates the adapter and diffuser to the base, at least an igniter supported by the adapter, a gas generating agent, and a filter disposed along the inner peripheral side of the side wall of the pressure vessel An inflator for an air bag,
The adapter includes a flange near the joint with the base,
It is the most important feature and Turkey a gap is provided between the outer peripheral end portion and the base of the front Kitsuba portion.

That is, the inflator of the present invention, the adapter is of Ru a gap is provided between the outer peripheral edge and the base of the flange portion provided near the junction with the base.

  By adopting such a configuration, compared to the conventional structure, as shown in FIG. 1, the deformation amount of the base 2c (portion indicated by a two-dot chain line) can be increased, and the stress concentration during deformation can be suppressed. As a result, the pressure vessel 2 can be prevented from being broken.

In the present invention, the adapter, Ru a gap is provided between the outer peripheral edge and the base of the flange portion provided near the junction with the base.

  Therefore, when the internal pressure rises and the pressure vessel is deformed, the amount of deformation of the base becomes large, the stress concentration generated in the base can be suppressed, and the pressure vessel can be prevented from being broken.

It is the figure which expanded and showed the junction part vicinity cross section of the base and adapter of this invention. It is the figure which expanded and showed the cross section near the junction part of the base which is a component of the inflator of the present invention, and an adapter, and (a) is the case where the peripheral edge part of the collar provided near the junction part is formed in a chamfered shape (B) is a case where a gap is provided between the outer peripheral end of the flange provided near the joint and the base, and (c) is an R-shaped outer peripheral end of the flange provided near the joint. It is a case where it forms. It is the figure which showed the result of the simulation using the conventional adapter shown in FIG. 9, FIG. 10, (a) is the figure which showed before gas generation, (b) after gas generation. It is the figure which showed the result of the simulation using the adapter of this invention shown in FIG. 1, (a) is before the gas generation, (b) is the figure which showed after gas generation. It is the figure which showed the result of the simulation using the adapter of this invention shown to Fig.2 (a), (a) is before the gas generation, (b) is the figure which showed after gas generation. Using the conventional adapter shown in FIG. 9 and FIG. 10 and the adapter of the present invention shown in FIG. 1 (gap shape) and FIG. 2 (a) (chamfered shape), three destructive tests were performed. It is the figure which showed the result. It is sectional drawing explaining the structure of a single stage type inflator. (A) is the figure which showed the pressure vessel before the internal pressure rise of an inflator, (b) is the figure which showed the pressure vessel after the internal pressure rise of an inflator. It is a figure explaining the fracture | rupture location S at the time of fracture | rupture in the pressure vessel of a conventional product at the time of fracture | rupture by the internal pressure rise by higher generated gas pressure. In a conventional pressure vessel, when the internal pressure increases due to a higher generated gas pressure, the base is deformed with the contact portion in the vicinity of the outer periphery of the joint between the adapter and the base as a fulcrum (state indicated by a two-dot chain line) FIG.

In the present invention, the object of preventing breakage of the pressure vessel due to an increase in internal pressure during gas generation is realized by providing a gap between the outer peripheral end portion of the flange portion provided in the vicinity of the joint portion of the adapter and the base .

Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.
The inventors considered that it is important to allow the deformation of the base in order to prevent damage to the pressure vessel when the internal pressure rises when gas is generated.

  Therefore, the inventors pay attention to the contact portion in the vicinity of the outer peripheral portion at the joint portion of the base and the adapter, and show the conventional shape shown in FIGS. 9 and 10 and FIGS. 1 and 2A to 2C. The pressure strength was simulated for the adapter 2b having a different shape. The results are shown in FIGS.

  FIG. 3 shows a conventional example shown in FIGS. 9 and 10 in which a chamfered shape or an R shape is not provided on the outer peripheral side end portion of the flange portion of the adapter 2b in the contact portion C with the base 2c, that is, the anti-joining portion side of the adapter 2b. The result of the simulation using an adapter is shown.

  In the drawing of FIG. 3A, a portion represented by a solid white line from the right side of the center portion shows the vicinity of the contact portion C between the adapter 2b and the base 2c. Two white solid lines are provided approximately in parallel in the vertical direction, the left side is long in the vertical direction, the right side is short in the vertical direction, and is provided in the horizontal direction so as to be in contact with the lower ends of the two parallel lines. . The right side of this white solid line shows the main part of the space 2d and the adapter 2b. There is a base 2c below the white solid line.

  When the conventional adapter 2b shown in FIGS. 9 and 10 is used, the simulation result shown in FIGS. 3A and 3B is obtained, and the internal pressure of the inflator when the base breaks is 8640 psi. .

  On the other hand, FIG. 4 shows the result of the simulation using the adapter of the present invention shown in FIG. 1 in which a distance of 2 mm is provided so that the base 2c does not contact the outer peripheral end of the flange of the adapter 2b. It is a thing. The distance between the outer peripheral end of the collar portion of the adapter 2b and 2 mm is shown in the substantially central portion of FIG.

  When the adapter 2b of the present invention having the shape shown in FIG. 1 is used, the simulation result shown in FIGS. 4A and 4B is obtained, and the internal pressure of the inflator when the base breaks is 10560 psi.

  FIG. 5 shows another adapter of the present invention shown in FIG. 2A, in which a chamfering shape of 2 mm is provided on the side opposite to the contact portion C at the contact portion C between the base 2c and the outer peripheral end of the flange portion of the adapter 2b. The result of the simulation using is shown. In addition, 2ba in FIG. 2 (a) shows a chamfering shape part, and it is shown by the part surrounded by the substantially center part and white circle of FIG. 5 (a).

  When the adapter 2b of the present invention having the shape shown in FIG. 2 (a) is used, a simulation result as shown in FIGS. 5 (a) and 5 (b) is obtained, and the internal pressure of the inflator when the base breaks is 9480 psi. there were.

  Next, three conventional adapters 2b having the conventional shape shown in FIGS. 9 and 10 and the shape of the present invention shown in FIGS. 1 and 2A were prepared and subjected to a destructive test. The result is shown in FIG.

  As is apparent from FIG. 6, the inflator having the conventional shape shown in FIGS. 9 and 10 was broken at approximately 8600 to 8700 psi.

  On the other hand, when the adapter 2b shown in FIG. 1 having a gap of 2 mm is provided so that the base 2c and the outer peripheral end of the flange portion of the adapter 2b do not contact each other, as shown in FIG. It broke at.

Further, when the adapter 2b shown in FIG. 2 (a) having a chamfer of 2 mm is provided on the side opposite to the contact portion C at the contact portion C between the base 2c and the outer peripheral end portion of the flange portion of the adapter 2b, it is shown in FIG. As such, it broke at about 9100-9500 psi.

  Thus, it can be seen that the results of the simulation and the test sample are well correlated. In particular, in the case of the adapter 2b shown in FIG. 1, the variation in the result of the destructive test is very small, and it can be seen that the adapter 2b is more preferable as an inflator with higher reliability.

The present invention, the simulation results, and was made based on the results of the destructive tests, in the vicinity of the junction Y2 between base over scan 2c and the adapter 2b, a gap so that the base 2c and the adapter 2b are not in contact An adapter 2b is formed .

  The present invention is not limited to the above examples, and it goes without saying that the embodiments may be appropriately changed as long as they are included in the scope of the technical idea described in each claim.

  That is, the airbag inflator described above is a preferred example of the present invention, and other embodiments can be implemented or performed by various methods. In particular, the present invention is not limited to the detailed shape, size, configuration, and the like of the components shown in the accompanying drawings unless otherwise specified in the present specification. In addition, expressions and terms used in the present specification are for the purpose of explanation, and are not limited thereto unless specifically limited.

  For example, the base 2c may be formed in a shape in which the base 2c and the adapter 2b are not in contact with each other in the vicinity of the joint portion between the base 2c and the adapter 2b. The present invention can also be applied to a double stage type inflator 1.

DESCRIPTION OF SYMBOLS 1 Inflator 2 Pressure vessel 2a Diffuser 2b Adapter 2ba Chamfered shape part 2bb R shape part 2c Base 3 Igniter 5 Gas generating agent 6 Filter Y2 Adapter-base junction C Adapter-base contact part

Claims (1)

Inside the pressure vessel that joins and integrates the adapter and diffuser to the base, at least an igniter supported by the adapter, a gas generating agent, and a filter disposed along the inner peripheral side of the side wall of the pressure vessel An inflator for an air bag,
The adapter includes a flange near the joint with the base,
An inflator for an airbag, wherein a gap is provided between an outer peripheral end portion of the flange portion and a base.