GB2272869A

GB2272869A - Vehicle air bag.

Info

Publication number: GB2272869A
Application number: GB9322325A
Authority: GB
Inventors: Motonobu Kitagawa; Takayasu Zushi; Kazuhiko Yamakawa; Hideo Nakajima; Masato Kuretake; Yoshimi Yoshida; Sawayo Uda
Original assignee: Takata Corp
Current assignee: Takata Corp
Priority date: 1992-11-30
Filing date: 1993-10-29
Publication date: 1994-06-01
Also published as: GB9322325D0; JPH06156174A; DE4338227A1

Abstract

The air bag comprises a plurality of pieces of cloth which are sewn together and which have a higher weave density in the vicinity of a seam than in any other portion and thus a higher stress resistance. The bag may be produced from circular pieces of cloth 24 cut from a textile having high density portions 21, 22. The resulting bag has a central portion 23 of low weave density which may constitute either a front or rear panel. In another embodiment (Figs 7, 8), the bag is of the type having centre (33) and side (43) panels, the panels again being cut from a textile having areas of different weave densities. <IMAGE>

Description

2272869

TITLE OF THE INVENTION

AIR BAG BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an air bag of an air bag device mounted on a vehicle and, more particularly, to an air bag composed of pieces of cloth which are sewn together and which have a higher strength at the peripheral portions thereof along the seam than at any other portion.. Descri2tion of the Related Art Fig. 3 is a perspective view of an air bag 1 for a driver in the spread state, and Fig. 5 is a perspective view of an air bag 2 for a passenger in the spread state.

Each of the air bags 1, 2 is provided with an opening 3, 4 at the rear end portion thereof into which an inflator is directly inserted or a gas ejected from the inflator is introduced. Vent holes 5, 6 are provided on the rear side of the air bag 1, 2 so that the gas in the air bag flows out through the vent holes 5, 6 when the occupant collides against the spread air bag 1P 2 gating the shock applied to an occupant.

thereby miti- The air bag 1 for a driver is composed of two pieces of circular cloth for a front panel 7 and a rear panel 8, respectively, sewn together. The edges 7a and 8a of the pieces of cloth for the front panel 7 and the rear panel 8 are joined and sewn together by a thread 9, as shown in Fig. 4.

The air bag 2 for a passenger is composed of a piece of cloth for a center panel 10 and two pieces of cloth for side panels 11 which are sewn together. The edges 10a and 11a of the pieces of cloth for the center panel 10 and the side panels 11 are joined and sewn together by a thread 12, as shown in Fig.6.

When such an air bag 1 (2) is completely inflated and spread at full size, or a human body is collided against the spread air bagi (2) a very large stress is applied to the joint portions of the panels 7 and 8 (10 and 11) of the air bag 1 (2).

In a conventional air bag, therefore, cloth having a high weave density is used for each panel so that the joint portion is sufficiently capable of resisting the stress applied thereto.

However, not only is cloth having a high weave density expensive but also since it is thick, the volume of the air bag in a folded state inconveniently becomes large, which results in a large-sized air bag device. OBJECT AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to eliminate the above-described problems in the related art and to provide an air bag at a low cost which can be folded compactly.

To achieve this aim, in a first aspect of the present invention, there is provided an air bag composed of a plurality of pieces of cloth sewn together, each piece having a higher weave density in the vicinity of a seam than in any other portion. in an air bag provided in a second aspect of the present invention, each piece of cloth is circular and is provided with a rectangular low-weave-density portion in the central portion thereof. in an air bag provided in a third aspect of the present invention, each piece of cloth is circular and is cut out of a textile having a continuous length. The textile has first high-weave-density portions which extend along the longitudinal side edges, second highweave-density portions which extend in the widthwise direction of the textile and provided at regular intervals which are equal to the width of the textile, and low-weave-density portions each of which is defined by the first and second high-weave-density portions. The circular piece of cloth is cut out of the textile in such a manner that the low-weavedensity portion is situated at the center of the circle and the first and second high-weave-density portions are situated at the pe-:7ipheral portions thereof.

Each piece of cloth constituting an air bag of the present invention has a high weave density only at the portion which is to become a joint portion when the edge thereof is sewn together with the edge of another piece of cloth. Therefore, the strength of the cloth cut out of the textile is sufficiently high at the joint portion and it is possible to secure a sufficiently high strength at the joint portion after the edges are sewn together. In addition, since the central portion of each piece of cloth has a low weave density and is thin, it is possible to fold the air bag compactly.

A textile is generally composed of woven warp yarns and filling yarns. By changing the weave density of the warp yarns and the filling yarns, it is possible to prepare a textile having square low-weave-density portions.

In an air bag provided in the second aspect of the present invention, a circular piece of cloth is cut out from such a textile in such a manner that the low-weave-density portion is situated at the center of the circle and the high-weave-density portion is situated at the peripheral portion thereof.

In an air bag provided in the third aspect of the present invention, the low-weave-density portions'are provided at predetermined intervals in the textile in the longitudinal direction, and a circular piece of cloth is cut out of the textile in such a manner as to contain the low-weave-density portion and the high-weave-density portions surrounding it.

The above and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view of a textile as a material of the cloth which constitutes an embodiment of an air bag for a driver according to the present invention; Fig. 2 is a perspective view of the embodiment of an air bag for a driver using the textile shown in Fig. 1; Fig. 3 is a perspective view of a conventional air bag for a driver; Fig. 4 is a sectional view of the conventional air bag for the driver shown in Fig. 3, taken along the line 4 - 4; Fig. 5 is a perspective view of an air bag for a passenger; Fig. 6 is a sectional view of the air bag for a passen-,ger shown in Fig. 5, taken along the line 6 - 6; Fig. 7 is a plan view of a textile as a material of the cloth which constitutes the center panel of an embodiment of an air bag for a passenger according to the present invention; and Fig. 8 is a plan view of a textile as a material of the -:c-1c.th which constitutes a side panel of the embodiment of an air bag for a passenger according to the present-invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present inventi4= will be explained hereinunder with reference to the accompanying drawings. Fig. 1 is a plan view of a textile as a material of the cloth which constitutes an embodiment of an air bag for a driver according to the present invention.

The textile 20 is provided with first high-weave-density portions 21 on both longitudinal side edges of the textile. Second high-weave-density portions 22 extending in the widthwise direction of the textile 20 are provided at regular intervals which are equal to the width of the textile 20. The square portion defined by the first and second high-weave-density portions 21, 22 is a low-weave-density portion 23.

A circular piece 24 of cloth is cut out of the textile 20 in such a manner as to contain the low-weave-density portion 23 in the central portion thereof. Two circular pieces 24 of cloth are sewn together, as shown in Fig. 4, to obtain an air bag 25 having a shape shown in Fig. 2.

In this air bag 25, since a joint portion 26 of a front panel 25a and a rear panel 25b is constituted by the first and second high-weave-density portions 21, 22, the strength A of the joint portion 26 after the edges of the panels 25a, 25b are sewn together is sufficiently high. Even if a strong tensile strength is applied to the cloth, the cloth is reliably prevented from being burst at the seam (not shown in Fig. 2). Since the central portion of each of the panels 25a and 25b is constituted by the low-weave-density portion 23 and is sufficiently thin, it is possible to fold the air bag 24 compactly, thereby realizing a smaller-sized air bag device.

Fig. 7 is a plan view of a textile 30 as a material of the cloth which constitutes the center panel of an embodiment of an air bag for a passenger according to the present invention. The textile 30 is also provided with first high-weave-density portions 31 on both longitudinal side edges of the textile 30 and second high-weave-density portions 32 extending in the widthwise direction of the textile 30 and provided at regular intervals. A center panel 34 is cut out of the textile 30 in such a manner as to contain the low-weave-density portion 33 defined by the high-weave-density portions 31, 32 in the central portion thereof.

Fig. 8 is a plan view of a textile 40 as a material of -the cloth which constitutes a side panel of the embodiment of an air bag for a passenger according to the present invention. The textile 40 is also provided with first high-weave-density portions 41 on both longitudinal side edges of the textile 40 and second high-weave-density portions 42 extending in the widthwise direction of the textile 40 and provided at regular intervals. A side panel 44 is cut out of the textile 40 in such a manner as to contain the low-weave-density portion 43 defined by the high-weavedensity portions 41, 42 in the central portion thereof.

The center panel 34 and the side panels 44 cut out of the textiles 30 and 40, respectively, are sewn together. The thus-obtained air bag for a passenger has also a high strength at the joint portions, and since the cloth is thin, it is possible to fold the air bag compactly.

An example of a texture suitable for the present invention will be cited in the following.

Material Yarn: Synthetic resin such as Nylon (trade name) and Tetron (trade name) Linear density of yarn: 150 to 950 deci-tex Density of high-weave-density portion: 40 to 100 (Number of yarns per inch) Density of low-weave- density portion: 20 to 60 (Number of yarns per inch) As described above, the air bag of the present invention has a high strength at the joint portions, and since most part of the cloth except for the joint portions is 8 - thin, it is possible to fold the air bag compactly, thereby realizing a smaller-sized air bag.

According to the present invention, it is easy to produce a piece of cloth which has a high-weave-density portion only at the peripheral portion.

Claims

WHAT IS CLAIMED IS:

1. An air bag comprising a plurality of pieces of cloth which are sewn together in the form of a bag and which have a higher weave density in the vicinity of a seam than in any other portion.

2. An air bag according to claim 1, wherein said cloth is a synthetic textile.

3. An air bag according to claim 2, wherein the linear density of yarn of said textile is 150 to 950 deci-tex, the number of yarns at the highweave-density portion of said textile is 40 to 100, and the number of yarns at the low-weave-density portion of said textile is 20 to 60.

4. An air bag according to claim 1, wherein said piece of cloth is circular and is provided with a low-weave-density portion in the central portion thereof.

5. An air bag according to claim 2, wherein said textile has a continuous length and includes first high-weave- density portions which extend along the longitudinal side edges of said textile, second high-weave-density portions which extend in the widthwise direction of said textile and are provided at regular intervals which are equal to the width of said textile, and lowweave-density portions each of which is - 10 defined by said first and second high-weave-density portions; and each of said plurality of pieces of cloth is cut out of said textile into a shape of a panel for said air bag in such a manner that said low-weave- density portion is situated in the central portion of said panel and said first and second high-weave-density portions are situated at the peripheral portions thereof.

6. An air bag according to claim 5, wherein said air bag is for a driver and said panel is either of the front panel and the rear panel of said air bag.

7. An air bag according to claim 5, wherein said air bag is for a passenger and said panel is either of a side panel and the center panel of said air bag.

8. An air bag substantially as hereinbefore described with reference to the accompanying description and Figures 1 and 2; or Figures 7 and 8 of the drawings.