JP3523678B2 - Gas generator for airbag - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generator for an airbag for protecting an occupant from an impact, and more particularly to a structure of a heat transfer tube. 2. Description of the Related Art A transfer tube constitutes a means for igniting a gas generating agent, and has a plurality of openings through which a flame of an igniter charged therein is jetted. The flame of the igniting charge propagates through the transfer tube, sequentially ejects from the opening, and ignites the gas generating agent in the opening area. FIG. 3 shows a conventional fire tube. In the related art, the openings 30 of the heat transfer tubes are uniformly distributed and formed in the tube wall of the heat transfer tubes. [0004] In the above-described conventional transfer tube, since the openings are uniformly dispersed, the ignition region of the gas generating agent increases proportionally with the propagation of the flame, Therefore, the passage of time and the generated gas pressure are almost proportional, and as a result, it has been difficult to adjust the deployment time of the airbag. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gas generator for an air bag having a novel structure of a heat transfer tube which solves the above-mentioned problems of the prior art. SUMMARY OF THE INVENTION A gas generator for an air bag according to the present invention has a cylindrical housing having a gas discharge port, and a transmission disposed in the housing and extending in the axial direction of the housing. A fire tube, a gas generating agent disposed around the transfer tube, an igniter charged inside the igniter tube, and an igniter for igniting the igniter; The tube is provided with a plurality of openings through which the flame of the igniting charge is ejected, and a gas generator that introduces gas generated from the gas generating agent by an impact into an airbag to protect an occupant from the impact, wherein the transmission tube is And a region where the opening is sparsely formed and a region where the opening is densely formed. The transfer tube is filled with an igniting charge, and the igniting charge ignites to generate a high-temperature flame. The flame propagates through the tube and sequentially blows out from openings formed in the tube. The spouted flame ignites the gas generating agent disposed in the opening area. In the region where the opening is sparsely formed, the amount of gas generated is small because the gas generating agent is sparsely ignited, and the combustion gas pressure is relatively small. Further, in the region where the openings are densely formed, the amount of generated gas is large because the gas generating agent is ignited densely, so that the combustion gas pressure becomes relatively large. As described above, since the amount of generated gas differs depending on the flame propagation region, it is possible to temporally adjust the amount of gas ejection and thereby adjust the deployment time of the airbag. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the gas generator. The gas generator has a cylindrical housing 1 closed at both ends. The housing 1 has a plurality of outlets 10 from which the combustion gas of the gas generating agent blows out in a region on the occupant side. In the housing 1, a fire tube 5 is disposed coaxially with the housing over the entire length of the housing.
5 are arranged side by side, and a filter 12 is arranged so as to surround the gas generating agent 15. An igniter 4 that is activated by a signal from a sensor (not shown) and an igniter 6 that is ignited by the igniter 4 are loaded inside the transfer tube 5. The igniter 4 is held by the adapter 2 attached to one end of the housing, and the igniter 6 is accommodated in the igniter container 3, and the igniter container 3 and the igniter 4 are in contact with each other. . Regarding the transmission tube 5, the side on which the igniter 4 is loaded is referred to as the ignition side C. The transfer tube 5 has a plurality of openings 7 through which the flame of the igniter 6 blows out. As shown in FIG. 2, these openings are sparsely formed in a region A near the ignition side C, and densely formed in a region B far from the ignition side C. The degree of sparseness and denseness can be defined by the numerical aperture per unit area, and the degree of sparseness and denseness can be defined by the ratio of the numerical aperture. When an impact is detected by the sensor, a signal is sent to the igniter 4 to activate the igniter 4, thereby igniting the transfer charge 6 and generating a high-temperature flame. This flame propagates in the transfer tube 5 and first blows out from the opening of the sparsely formed region A on the ignition side C. The erupted flame is in area A
Ignition of the gas generant arranged in the. Since this ignition sparsely ignites the gas generating agent, the amount of gas generated by combustion of the gas generating agent is relatively small. Next, the flame is blown out from the opening of the region B that is densely formed. The ejected flame ignites the gas generating agent disposed in the region B densely, so that the amount of generated gas is relatively large. On the other hand, during this period, the combustion of the gas generating agent propagates in the region A, and the amount of generated gas increases accordingly. As described above, the gas amount is initially small, and then the gas amount is large. The combustion gas passes through the filter 12, and the purified gas from which the combustion residue is removed flows into the airbag (not shown) through the outlet 10. The airbag initially inflates slowly and softly and then rapidly to protect the occupant from impact. According to the present invention, the amount of gas generated according to the flame propagation region can be made different as described above, whereby the amount of gas emission can be adjusted temporally. The deployment time of the airbag can be adjusted. According to the present invention, the amount of gas blown out is first reduced to prevent the airbag from inflating abruptly, thereby avoiding a sudden collision of the bag with the occupant. A gas generator for an airbag that is fired into the interior and thereby protects the occupant from impact can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of the present gas generator. FIG. 2 is a plan view of a heat transfer tube provided in the gas generator. FIG. 3 is a plan view of a conventional heat transfer tube. [Description of Signs] 1 housing 4 igniter 5 transfer tube 6 igniter 7 opening 10 outlet 15 gas generating agent

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60R 21/16-21/32

Claims (1)

(57) Claims: (1) A cylindrical housing having a gas discharge port, a heat transfer tube disposed in the housing and extending in the axial direction of the housing, It has a gas generating agent disposed around, an igniter charged inside the transfer tube, and an igniter for igniting the igniter, wherein the transfer tube emits a flame of the igniter. A gas generator that has a plurality of openings to protect the occupant from an impact by introducing a gas generated from the gas generating agent into the airbag by an impact, wherein the transmission tube has the openings sparsely formed. A gas generator for an airbag, characterized by having a region where the opening is formed and a region where the opening is densely formed.