AIR BAG IN AIR BAG UNIT

Abstract: An air bag (1) in an air bag unit which is inflated by a high-pressure gas ejected from an inflator actuated in an emergency is formed of a woven fabric of hollow weaving having single weaving (6) at least part of its lug portion (2). Thus the air bag (1) can be produced by forming in advance a base cloth (5) of the air bag (1) made of the woven fabric of hollow weaving woven in single weaving (6) at its predetermined portion and merely cutting the base cloth (5) at its single weaving portion (6). In this case, since hollow weaving in which a predetermined portion is woven in single weaving and the other portions in cylindrical shapes can be made easily by a machine, the base cloth (5) can be formed easily. For this reason, work manhour can be reduced drastically and automated production of air bags becomes possible. Accordingly, productivity can be improved drastically and the air bag can be produced economically.

Description: FIELD OF THE INVENTION The present invention relates to an air bag unit for protecting an occupant in a vehicle by absorbing the shock caused during vehicle collision, and in particular to an air bag in an air bag unit for receiving the occupant pushed forward as the bag is inflated by high pressure gas from an inflator at the collision. TECHNICAL BACKGROUND An air bag unit is installed on a fixed portion of car body in front of seat in a vehicle. In an emergency such as vehicle collision, the air bag is inflated instantaneously by the pressure of reaction gas released from an inflator, which is fixed on a fixed portion of car body such as steering wheel or lower portion of instrument panel. Thus, the air bag plays an important role for protecting the occupant from injury caused by collision against car body. As shown in Fig. 5, such air bag unit 01 comprises an inflator 02, which releases gas as gas generating agent is exploded by collision signal from collision detecting sensor when the deceleration of the vehicle exceeds a certain level, and an air bag 03, which is fixed with respect to the inflator 02 at its base and is inflated by the gas blown out from the inflator 02. With the air bag 03 folded up and placed in a pad, the air bag unit 01 is mounted on a fixed portion of the car body such as central portion of a steering wheel 04 or lower portion of instrument panel 05. Then, as shown in Fig. 5, the gas generating agent in the inflator 02 reacts when the vehicle is collided, and the air bag 03 is instantaneously inflated and expanded by the generated gas. As the result, the air bag 03 receives the occupant M, who is pushed forward by inertia and protects the occupant M from the collision against car body. Of such air bag 03 in an air bag unit 01, the air bag 03 for an occupant other than the driver is formed as shown in Fig. 6 (A) as follows: From a piece of base cloth, bag main unit 03a and a pair of lateral segments 03b and 03c, against which the occupant strikes, are cut into the predetermined shapes, and these are sewn up with lugs as shown in Fig. 6 (B). However, when a plurality of the components (03a, 03b and 03c) of the air bag 03 are cut from a piece of base cloth and are sewn, many steps of processes are required. Moreover, because it is difficult to mechanize the sewing of base cloth and the sewning of edges, all these works must be done manually, and the works need much labor because there are many points to sew up. For this reason, the productivity of air bag has been not very high in the past. From EP-A-0363490 there is known an air bag for an air bag unit according to the preamble of claims 1 and 3 that is inflated by high pressure gas from an inflator, said air bag being formed from a hollow weave cloth that is partially woven in single weave whereby the hollow weave portion of the cloth forms an envelope that is closed by the single weave portion. The present invention provides such an air bag which is characterised in that the single weave portion provides two opposite edges which converge toward one another such that the air bag has a narrow width at one end and a substantially greater width at an opposite end; and that portions of said air bag at said two opposite edges at said opposite end having a substantially greater width are overlapped and bonded so that a substantially rectangular face is formed at said opposite end of the air bag. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an embodiment of an air bag in an air bag unit according to the present invention; Fig. 2 shows the manufacturing process of this air bag, where (A) is a drawing of base cloth to be used for the manufacture of the air bag, (B) is a cross-sectional view of Fig. 2 along the line II B - II B, (C) is a drawing of component of the air bag, which is formed by cutting base cloth into a predetermined shape, and (D) shows an air bag component formed in the desired shape; Fig. 3 shows the variations of the air bag in Fig. 1, where (A) is a drawing similar to Fig. 2 (D), (B) is a cross-sectional view of Fig. 3 (A) along the line III B - III B, and (C) is a side view of the air bag when it is inflated; Fig. 4 is a drawing similar to Fig. 2 (A) showing a variation of base cloth; Fig. 5 shows a commonly used air bag unit, which is installed in a vehicle; and Fig. 6 shows a conventional type air bag, where (A) shows the components of the air bag, and (B) is a perspective view when the components are sewn up. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an air bag 1 of Fig. 1, the edges 2 are formed by hollow weave through single weave of lateral cloths a and b. The air bag 1 is provided with an opening 3 at upper end, while the bottom is formed in rectangular shape. When inflated, it has a form of truncated cone (or truncated pyramid or a composite of these two). An inflator (not shown) is inserted into the air bag 1 through an opening 3, and the opening 3 is fixed on the inflator. Fig. 2 shows a base cloth used for the manufacture of the air bag 1, and it also shows the manufacturing process of the air bag 1. As shown in Fig. 2 (A), the base cloth 5 of the air bag 1 is woven in cylindrical shape. As it is evident from Fig. 2 (B), it is formed from a woven cloth in hollow weave where the predetermined portion is woven in single weave 6. This single weave portion 6 is provided to match the shape of the air bag to be produced. As shown in Fig. 2 (A), by cutting the base cloth 5 along the line (a) - (a) on a single weave portion 6, the air bag component 7 shown in Fig. 2 (C) is formed. The air bag component 7 is cut along the line (b) - (b) to provide an opening, and the portions c and d of the air bag component 7 are overlapped and bonded 8 by adequate methods such as sewing, bonding, welding, etc. Thus, an air bag member 9 with its bottom in approximately rectangular shape can be obtained. By putting this air bag member 9 inside out, the air bag 1 of Fig. 1 is formed. In this case, the portions c and d may be partially cut. In such air bag 1, the air bag 1 can be manufactured simply by cutting the base cloth 5 in hollow weave with its part woven in single weave into the predetermined shape on the single weave portion and by bonding 8 to adjust the shape of the air bag. In such case, unlike the conventional case where a plurality of components cut into the predetermined shape are sewn up by aligning the edges, bonding is performed by simply bonding at the predetermined positions, and much labor is not required for such procedure. Therefore, it contributes to the reduction of the processes to manufacture the air bag 1 and to the production of air bag 1 in short time and at low cost. Moreover, it is possible to mechanize the air bag production because the procedure such as the procedure to cut a plurality of air bag components and the procedure to sew up by aligning the edges can be eliminated. Further, to produce an air bag for an occupant other than the driver, the portion "e" may be bonded together by adequate method such as sewing, bonding or welding as shown in Figs. 3 (A) and (B). As the result, it is possible to form an a ir bag 1 of top mount type for the above occupant, in which the directions of the opening 3 and the bottom 4 are varied by a predetermined angle as shown in Fig. 3 (C). Fig. 4 shows a variant of the base cloth 5. In the variants and other embodiments described below, the same component is referred by the same symbol, and detailed description is not given. In Fig. 4, the base cloth 5 of hollow weave has its part in single weave portion 6 as in the case of base cloth shown in Fig. 2 (A). In this embodiment, the single weave portion 6 is formed in trapezoid. As the result, the opening for the inflator is provided, and the strength of the portion (lower portion in the figure) where inflator is attached can be increased. In the above embodiment, the opening 3 where the inflator is inserted is formed by cutting along the line (b) - (b) in Fig. 2 (C), whereas the opening 3 may be formed at the other adequate position as shown by two-dot chain line in Fig. 2(C). APPLICABILITY FOR THE INDUSTRY The air bag in an air bag unit according to the present invention can be used on a vehicle and applied for the purpose of protecting the occupant by absorbing the shock which occurs when the vehicle is collided.

Claims: An air bag (1) for an air bag unit that is inflated by high pressure gas from an inflator, said air bag being formed from a hollow weave cloth (5) that is partially woven in single weave (6) whereby the hollow weave portion (5) of the cloth forms an envelope that is closed by the single weave portion (6), characterised in that the single weave portion (6) provides two opposite edges (2) which converge toward one another such that the air bag (1) has a narrow width at one end and a substantially greater width at an opposite end; and that portions (c), (d) of said air bag (1) at said two opposite edges (2), (2) at said opposite end having a substantially greater width are overlapped and bonded so that a substantially rectangular face is formed at said opposite end of the air bag (1). An air bag (1) for an air bag unit according to Claim 1, wherein said air bag (1) includes an opening (3) adjacent to said one end having a narrow width for injecting high pressure gas. A method of making an air bag unit, comprising the steps of weaving a generally cylindrical hollow weave base cloth (5) with portions (6) thereof in single weave whereby the hollow weave portions (5) of the base cloth define envelopes closed by the single weave portions (6) and cutting the base cloth (5) along the single weave portions (6), to separate the envelopes and form individual air bags (1), characterised in that said single weave portions (6) are spaced apart along the cylindrical axis of the hollow weave and are so arranged that single weave portions (6) converge together from one side of the cylinder to the other to define trapezium shaped envelopes. A method of making an air bag unit according to Claim 3, characterised in that at least three single weave portions (6) are provided, each of uniform width, and are so arranged that three consecutive single weave portions define two said envelopes. A method of making an air bag according to Claim 3, characterised in that the single weave portions (6), each have a trapezoidal shape and are so arranged that the defined trapezoidal envelopes converge in the same direction. A method of making an air bag unit according to any one of Claims 3 to 6 characterised in that it further includes the step of overlapping portions (c), (d) of the trapezium shaped envelope at the wider end and bonding these portions (c), (d) so as to form a generally rectangular passenger receiving face. A method according to any of Claims 3 to 6, further including the step of cutting an opening (3) for injecting high pressure gas into the individual air bag (1).

Inventors: TAKAMIYA TOSHIO ANJIKINAKA-CHO, TAKAMIYA, TOSHIO 178, ANJIKINAKA-CHO
Applicants: TAKATA CORP, TAKATA KABUSHIKI KAISHA
Application year: 1990
Main classification: B60R21
IPC codes: D03D11, B60R21, D03D1