Gas generating agent of air bag inflation gas generator

Abstract: This invention relates to an air bag inflation gas generator used to inflate air bags such as air bags for impact safety devices, life jackets, rafts, and excape chutes, and particularly to a gas generating agent disposed within the device (71) to generate a combustion gas. This invention is structured by forming spacer projections, to keep adjacent gas generating agent bodies at certain intervals, on one side of the gas generating agent bodies having a through hole (89) formed in the axial direction.

Description: The invention relates to a gas generating agent of an airbag inflation gas generator according to the preamble of claim 1. Such a gas generating agent of an airbag inflation gas generator is known from EP-A3-0 291 817. The generally cylindrically shaped gas generating bodies are, according to this document, stacked on top of one another. In order to secure a certain distance between them, each body comprise spacer projections situated on the end portions thereof. The projections are formed as equidistant annular segments of a peripheral ring. The gases generated on each gas generating agent body are disturbed by said spacer projections since a collision between the gases and the spacer projections take place during the flow of the gases. Because of such collisions the gases flow back and, as a result, complicated gas flow configurations may be observed. Thus, the resistance against the gas flow is increased such that the gas pressure applied to the surfaces of each gas generating agent body is rather high. From DE-A1-3 907 089 a gas generating agent body is known which comprises two spacer projections which are formed like a dot. It is an object of the present invention to form a gas generating agent of an airbag inflation gas generator by which passages for smoothly flowing of the generated gas are ensured. This object is solved by a gas generating agent of an airbag inflation gas generator comprising the features of claim 1. Preferred embodiments of the invention are stated in the subclaims. In the following, a preferred embodiment of the present invention is described with respect to the drawings in which Fig. 1 is a partly vertical section showing an airbag inflation gas generator having the embodiment of a gas generating agent of this invention; Fig. 2 is a transverse sectional view taken on line A-A of Fig. 1; Fig. 3 is a partly sectional view of the gas generating agent pack of Fig. 1; and Fig. 4 is a perspective view showing the gas generating agent to be contained in the gas generating agent pack of Fig. 3. Fig. 1 and Fig. 2 show an airbag inflation gas generator having the embodiment of a gas generating agent of this invention, and in the drawings, the reference numeral 55 indicates a longitudinal outer cylindrical member sealed by an end plate part 57 on one side and an end plate part 59 on the other side. The outer periphery of the outer cylindrical member 55 has a number of gas outlets 61 formed. And, a part 63 to be mounted on a vehicle is integrally formed on the end plate part 59. The outer cylindrical member 55 has a cylindrical final filter 65 disposed therein. This final filter 65 is formed by winding, for example, fine-mesh woven metal wire, close-woven metal wire, etc. in layers. This filter has the functions that the combustion gas is cooled so that the airbag is not damaged, the combustion residue contained in the combustion gas is removed, and harmless nitrogen gas only is supplied into the air bag. Inside the final filter 65 is inserted an inner cylindrical member 67. The inner cylindrical member 67 has many gas flow openings 69 formed in the entire length of the outer periphery thereof. The inner cylindrical member 67 accommodates a gas generating agent pack 71. The gas generating agent pack 71 has a bottom-closed longitudinal cylindrical pack 73 made of aluminum as shown in Fig. 3. Within the cylindrical pack 73, many gas generating agents 77 having a through hole 75 formed in their center are accommodated in the stacked state in the axial direction. One end of the cylindrical pack 73 is sealed by one end face 79, and the other end is sealed by another end face 82 made of, for example, an aluminum cap 81. At one end of the cylindrical pack 73, a cylindrical cushion material 83 is disposed. This cushion material 83 is for example formed of expanded silicone rubber, which acts as an energizing means to energize the gas generating agents 77 toward the cap 81 with its elasticity. And, an ignition agent 84 is disposed at the center of the cushion material 83. The ignition agent 84 is accommodated in an ignition agent pack 85, and a bottom 86 of the ignition agent pack 85 is contacted to the one end face 79 of the cylindrical pack 73. On the other hand, the cap 81 disposed on the other end of the cylindrical pack 73 is tightly wound around its outer periphery by the cylindrical pack 73 to have a cylindrical fasten-folded section 87. And, at the center of the cap 81 is formed a projection 88 to accommodate the ignition agent 84. The ignition agent 84 is accommodated in the ignition agent pack 85. As shown in Fig. 1, the end plate part 57 sealing one end of the outer cylindrical member 55 is made of an end cap and caulked by the outer cylindrical member 55 for fixing. At the center of the end plate part 57, a through hole 89 is formed, and an igniter 90 is inserted into the through hole 89 and caulked by the end plate part 57 for fixing. A packing 91 made of, for example, inflammable silicone rubber, is disposed between one end of the final filter 65 and the end plate part 57 and between the other end of the final filter 65 and the end plate part 59. In the preferred embodiment, an energizing member 93 is disposed between the cap 81 forming the other end face 82 of the gas generating agent pack 71 and the end plate part 59 of the outer cylindrical member 55. This energizing member 93 is cylindrical and disposed between the fasten-folded section 87 and the projection 88. And, the energizing member 93 is formed of, for example, expanded silicone rubber, which acts as an energizing means to energize the gas generating agent pack 71 toward the igniter 90 with its elasticity. In the preferred embodiment, the gas generating agents 77 have spacer projections 97A formed on one side of a gas generating agent body 97 as shown in Fig. 4 so that the neighboring gas generating agent bodies 97 are kept at certain intervals. Specifically, the gas generating agent body 97 is circular with a circular through hole 75 formed in its center, and the spacer projections 97A are integrally formed in the shape of cross on one side of the gas generating agent body 97. And, the spacer projections 97A are formed like linear stripes with an equal angle space apart and extend from the through hole 75 to the outer circumferential surface of the gas generating agent body 97. Furthermore, the spacer projections 97A have their cross sections formed into a triangle with its tip tapered. The shape of each cross section is not limited to a triangle but may be a trapezoid, semicircle or the like. The spacer projections 97A preferably have a height of 0.2 to 1 mm to keep a space between the adjacent gas generating agent bodies 97. With the aforementioned airbag inflation gas generator, the ignition agent 84 burns when electricity is sent to the igniter 90, which in turn burns the gas generating agents 77, the cylindrical pack 73 of the gas generating agent pack 71 is broken at the gas flow openings 69 of the inner cylindrical member 67, the combustion gas flows into the final filter 65 through the gas flow openings 69 of the inner cylindrical member 67 and is purified by the final filter 65, then it is flown into the gas bag through the gas outlets 61 of the outer cylindrical member 55. Since the gas generating agents of the airbag inflation gas generator constructed as described above have the spacer projections 97A formed on one side of the gas generating agent body 97 which has the through hole 75 formed in the axial direction so that the neighboring gas generating agent bodies 97 are kept at certain intervals, it is easily possible to make a separator disposed between the gas generating agents 77 needless. As a result, the assembling steps and production costs can be reduced. And, since the spacer projections 97A are formed in the shape of a cross in the preferred embodiment the gas generating agents 77 are hardly cracked by a stress applied in the axial direction, and the gas generating agents 77 are easily ignited by the flame of the ignition agent 84.

Claims: A gas generating agent of an airbag inflation gas generator comprising spacer projections (97A) formed on one side of a gas generating agent body (97) having a through hole (75) formed in the axial direction, in order to keep a space between adjacent gas generating agent bodies (97), characterized in that slid spacer projections (97A) are formed like linear stripes with an equal angle space apart and extend from the through hole (75) to the outer circumferential surface of the gas generating agent body (97). A gas generating agent according to claim 1, characterized in that each spacer projection (97A) has a height of 0.2 to 1 mm. A gas generating agent according to claims 1 or 2, characterized in that the gas generating agent body (97) is circular with a circular through hole (75) formed in its center and that the spacer projections (97A) are integrally formed in the shape of cross. A gas generating agent according to one of the foregoing claims, characterized in that each spacer projection (97A) has a cross section formed in the shape of a triangle, trapezoid or semicircle with its tip tapered.

Inventors: KISHIMOTO JUNICHI, KOBARI HIROKAZU, SHIOTA MICHIO, KISHIMOTO, JUNICHI, KOBARI, HIROKAZU, SHIOTA, MICHIO
Applicants: NIPPON KOKI KK, NIPPON KOKI CO., LTD.
Application year: 1993
Main classification: B60R21
IPC codes: C06D5, B60R21, B01J7