AIR-BAGGED SEAT

Abstract: An air bag storage portion (22a) of a cover member (25) that covers a seat back (22) includes a seat-back front cover element (25a) and a side cover element (25b) that are sewn together. An air bag module (30) is provided with a casing (31) that contains an air bag (32) and an inflator (33) therein. The casing (31) includes a tubular guide portion (34) that has two opposite side walls (31a, 31b), a top wall (31c), and a bottom wall (31d). The front end of the guide portion (34) is formed having a front opening (40) that is directed toward a sewing portion (26) between the seat-back front cover element (25a) and the side cover element (25b).

Description: D E S C R I P T I O N AIR- BAGGED SEAT Technical Field This invention relates to an air-bagged seat provided with a side air bag capable of effectively protecting a user when a vehicle is subjected to a lateral force of impact. Background Art An air bag that is mounted in a vehicle such as an automobile is caused instantaneously to bulge by means of gas that is generated by an inflator in case of a collision. The inflated air bag restrains a user from undergoing a second collision with some interior members. To cope with a head-on collision, the air bag may be effectively located in front of the user, that is, in a center pad of a steering wheel, or near a glove box in front of a passenger seat. A side impact can be effectively tackled by a so-called side air bag that is incorporated in a seat back or the like. For example, a conventional side-air-bagged seat 1 shown in FIG. 7 is provided with an air bag module 4 that is incorporated in a side portion 3 of a seat back 2 that, out of a pair of side portions, left and right, is nearer to a door. An inflator 5 is actuated in response to a signal delivered from a sensor when the vehicle is subjected to a side impact, whereupon the air bag 6 is inflated with gas that is generated by the inflator 5. The seat back 2 includes a frame 7, pad 8, cover member 9, etc. As the air bag 6 unfolds, thread 11 in a sewing portion 10 between a seat-back front cover element 9a and a side cover element 9b is broken by pressure that acts thereon from inside the cover member 9. The air bag 6 bulges forward ( in the direction indicated by arrow F) from the seat back 2 through the broken portion, as indicated by two-dot chain line (shown in FIG. 7), and unfolds into a shape such that it can protect the flank, temple, etc. of the user. The air bag 6 is stored together with the inflator 5 in a box-shaped casing 15. The casing 15 is provided with a casing body 15a fixed to the frame 7 and a lid 15b attached to the casing body 15a and situated between the casing body 15a and the side cover element 9b. The lid 15b is swingable around a hinge portion 16. The lid 15b can be kept on in a manner such that retaining portions 17 such as hooks on the front end of the casing body 15a are anchored individually to receiving portions 18 that are formed on the lid 15b, as shown in FIG. 8. The air bag 6 in this air bag module 4 unfolds when the lid 15b is swung open around the hinge portion 16 as the air bag 6 inflates, as shown in FIG. 9. As shown in FIG. 10, the inflator 5 is stored in the casing 15. As the gas is jetted out forcibly from injection nozzles 5a of the inflator 5, the lid 15b swings open sideways with respect to the seat back or toward the side cover element 9b. In the prior art example described above, a front edge portion C of the lid 15b and the like sometimes may abut hard against the side cover element 9b (shown in FIG. 7) when the lid 15b is taken off. Accordingly, stress is concentrated on a contact portion between the front edge portion C and the side cover element 9b, so that the side cover element 9b may possibly tear as the air bag 6 unfolds. In this case, the unfolding pressure of air bag 6 cannot easily act on the sewing portion 10, so that the unfolding performance of the air bag 6 may possibly be influenced. Accordingly, the object of the present invention is to provide an air-bagged seat in which a side cover element or any other region than a sewing portion can be prevented from tearing when an air bag unfolds, so that the air bag can display proper unfolding performance. Disclosure of Invention In order to achieve the above object, according to the present invention, there is provided an air-bagged seat having an air bag module in a seat back, in which a cover member for covering an air bag storage portion of the seat back includes a seat-back front cover element and a side cover element sewn together, the air bag module is provided with a casing containing an air bag and an inflator therein and fixed to a frame of the seat back, and the casing includes a tubular guide portion having two opposite side walls, a top wall, and a bottom wall, the front end of the guide portion having a front opening directed toward a sewing portion between the seat-back front cover element and the side cover element. According to the air-bagged seat of the present invention, gas jetted out from the inflator is introduced into the air bag in case of a collision. The air bag is inflated with this gas . The air bag projects forward from the front opening through the guide portion of the casing and unfolds toward a sewing portion of the cover member. Thread in the sewing portion is broken as this air bag unfolds steadily in a regular direction. The shock of a second collision between a user and interior members can be eased by the air bag unfolded in this manner. The air bag stated herein is a member that can be inflated like a bag with gas, such as nitrogen gas. It is to be understood that any kinds of gases may be used for inflation. This invention further comprises a front cover provided on the front end of the guide portion of the casing, covering the opening, and adapted to expose the opening when the air bag unfolds . The front cover can be swung open toward the frame around a hinge portion situated closer to the frame. According to this invention, the front cover swings open toward the frame of the seat back around the hinge portion when the air bag unfolds, so that the front cover can be prevented from abutting against the cover member such as the side cover element . Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. Brief Description of Drawings The accompanying drawings , which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. FIG. 1 is a cross-sectional view of part of an air-bagged seat according to a first embodiment of this invention; FIG. 2 is a perspective view of the air-bagged seat shown in FIG. 1; FIG. 3 is a perspective view of an air bag module used in the air-bagged seat shown in FIG. 1; FIG. 4 is a perspective view of the air-bagged seat shown in FIG. 1 with its air bag unfolded; FIG. 5 is a perspective view of an air bag module according to a second embodiment of this invention; FIG. 6 is a perspective view of the air bag module shown in FIG. 5 with its air bag unfolded; FIG. 7 is a cross-sectional view of part of a conventional air-bagged seat; FIG. 8 is a perspective view of an air bag module used in the air-bagged seat shown in FIG. 7; FIG. 9 is a perspective view of the air bag module shown in FIG. 8 with its air bag unfolded; and FIG. 10 is a side view of the air bag module shown in FIG. 8. Best Mode of Carrying Out the Invention An embodiment of this invention will now be described with reference to FIGS. 1 to 4. A side-air-bagged seat 20 shown in FIGS. 1 and 2 is applicable to a front seat of an automobile. The seat 20 is provided with a seat cushion 21 and a seat back 22. The seat back 22 is provided with a seat back frame 23, a pad 24 formed of, e.g., polyurethane foam, and a cover member (front seat trim cover) 25 that externally covers the seat back frame 23, pad 24, etc. The cover member 25, which constitutes a covering of the seat back 22, is formed by cutting a cover element of, e.g., artificial leather into a given shape and sewing it. The artificial leather is a cover element obtained by coating the outer surface of knitted fabric for use as a back fabric base with an elastomer layer. Natural leather or woven fabric may be used as a cover element for the cover member 25. A side portion 22a of the seat back 22 functions as an air bag storage portion. Part of the cover member 25 that covers the side portion 22a includes a seat-back front cover member 25a for use as a first cover element and a side cover element 25b for use as a second cover element. These cover elements 25a and 25 are sewn together at a sewing portion 26 by means of sewing thread 27. The seat-back front cover element 25a constitutes the front face of the seat back 22, while the side cover element 25b constitutes a side face of the seat back 22. The cover member 25 that covers the side portion 22a may be formed by combining the seat-back front cover element 25a, side cover element 25b, and some other cover elements. A bracket 28 is fixed to the lateral of the seat back frame 23 by welding or the like. The bracket 28 includes a mounting plate 28a having a shape such that it extends along an air bag module 30, which will be described below. The air bag module 30 is incorporated in the side portion 22a that, out of two opposite side portions 22a and 22b of the seat back 22, is nearer to a door. The air bag module 30 is provided with a casing 31 (shown in FIG. 3), an air bag 32 stored flat in the casing 31, an inflator 33 for generating inflator gas such as nitrogen gas, etc. The casing 31 is fixed to the mounting plate 28a of the bracket 28 of the seat back frame 23. The casing 31 includes a tubular guide portion 34 that has two opposite side walls 31a and 31b, a top wall 31c, and a bottom wall 3Id. As shown in FIG. 1, a bolt 36 is provided on the rear part of the casing 31. The casing 31 is fixed in a predetermined position on the bracket 28 by passing the bolt 36 through a hole in the mounting plate 28a and fastening a nut 37 to the bolt 36 in an engaged manner. The inflator 33 is connected with an ignition system, which includes a sensor for detecting a side collision of a vehicle, a power source (not shown), etc. A front opening 40 is formed in the front end of the guide portion 34 of the air bag module 30. The front opening 40 is directed toward the sewing portion 26 between the seat-back front cover element 25a and the side cover element 25b and opens in front of the casing 31. All the regions of the casing 31 except the front opening 40, that is, the opposite side walls 31a and 31b, the top wall 31c, the bottom wall 3Id, a rear wall 31e, etc. of the guide portion 34, are linked to one another in the form of a box having an internal space defined therein. These walls 31a, 31b, 31c and 31d function also as guides for regulating the unfolding direction of the air bag 32 so that the air bag 32 can be directed toward the front opening 40. The following is a description of the operation of the air-bagged seat 20 with the air bag module 30. When the vehicle receives a lateral force of impact, the inflator 33 is actuated in response to a signal delivered from the sensor for detecting a collision of the vehicle, whereupon the inflator gas such as nitrogen gas is jetted out from injection nozzles 33a of the inflator 33. The jetted gas is ejected into the air bag 32 in a manner such that the direction of its ejection is regulated by the casing 31. When the air bag 32 starts to be inflated with the gas jetted out by the inflator 33, the air bag 32 projects toward the front opening 40 through the guide portion 34 of the casing 31, and unfolds ahead of the casing 31 through the front opening 40, that is, toward a position near the sewing portion 26. The air bag module 30 according to this embodiment, unlike the conventional air bag module, is not provided with any lid that swings open sideways with respect to the seat, so that the side cover element 25b can be prevented from being torn by the lid. Thus, the unfolding force of the air bag 32 acts directly on the sewing thread 27 in the sewing portion 26, so that the sewing thread 27 in the sewing portion 26 breaks without fail. This air bag 32 spreads out in the direction indicated by arrow F, as indicated by two-dot chain line in FIG. 1. FIG. 4 shows the air bag 32 in its unfolded state. Since the unfolded air bag 32 is located in a space between the flank of a seated user's body and an inner side wall of the vehicle body, the shock of a second collision between the user and the inner side wall of the vehicle body can be eased. FIG. 5 shows a second embodiment of this invention. In the case of this embodiment, a front cover 50 for closing the front opening 40 is provided on the front end of the guide portion 34 of a casing 31. For other arrangements and effects, this embodiment is similar to the foregoing embodiment (FIGS. 1 to 4). Therefore, portions common to the two embodiments are designated by common numerals, and a description of those portions is omitted. The casing 31, like the one according to the foregoing embodiment (FIG. 1), is fixed to the bracket 28 of the seat back frame 23. The front cover 50 is swingable around a hinge portion 51 on that edge portion of the front opening 40 which is situated closer to the bracket 28. The front cover 50 can be kept on the casing 31 in a manner such that retaining portions 52 such as hooks on the casing 31 are anchored individually to receiving portions 53 such as holes in the cover 50. As the air bag 32 unfolds, as shown in FIG. 6, the front cover 50 swings toward the frame 23 around the hinge portion 51, whereupon the front cover 50 is undone. When the air bag 32 unfolds, in an air bag module 30 (FIGS. 5 and 6) having the front cover 50 constructed in this manner, the air bag 32 projects toward the front opening 40 through the guide portion 34 of the casing 31, and unfolds toward the sewing portion 26 (shown in FIG. 1) of the cover member 25 through the front opening 40. The front cover 50 according to this embodiment, unlike the conventional lid, never swings open sideways with respect to the seat. In other words, the air bag module 30 according to this embodiment is not provided with any lid that abuts against the side cover element 25b when the air bag 32 unfolds, so that the side cover element 25b can be prevented from being torn by the lid. In the embodiment described herein, the air bag module 30 is supposed to be incorporated in the seat back 22 of a passenger seat in a right-hand wheel vehicle. According to this invention, however, the same effect as aforesaid can be obtained by incorporating an air bag module 30 similar to the one according to the foregoing embodiment in a door-side portion of the seat back of a driver's seat, for example . Industrial Applicability The air-bagged seat according to this invention, unlike the conventional air-bagged seat, is not provided with any lid that swings open sideways with respect to the seat as the air bag unfolds, so that the cover member such as the side cover element can be prevented from being torn by the lid when the air bag unfolds, and therefore, the air bag can display proper unfolding performance. The air-bagged seat of this invention is suited for use in a vehicle such as an automobile. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims: C A I M S 1. An air-bagged seat (20) having an air bag module (30) in a seat back (22), characterized in that: a cover member (25) for covering an air bag storage portion (22a) of said seat back (22) includes a seat-back front cover element (25a) and a side cover element (25b) sewn together; said air bag module (30) is provided with a casing (31) containing an air bag (32) and an inflator (33) therein and fixed to a frame (23) of the seat back (22); and said casing (31) includes a tubular guide portion (34) having two opposite side walls (31a, 31b), a top wall (31c), and a bottom wall (3Id), the front end of the guide portion (34) having a front opening (40) directed toward a sewing portion (26) between said seat-back front cover element (25a) and the side cover element (25b) . 2. An air-bagged seat (20) according to claim 1, further comprising a front cover (50) provided on the front end of the guide portion (34) of said casing (31), covering said opening (40), and adapted to expose the opening (40) when the air bag unfolds, the front cover (50) being capable of being swung open toward the frame (23) around a hinge portion (51) situated closer to said frame (23) .

Inventors: MURATA YOSHIAKI, TAKAZAWA SYUNJI, MURATA, YOSHIAKI, TAKAZAWA, SYUNJI
Applicants: MURATA YOSHIAKI, NHK SPRING CO LTD, TAKAZAWA SYUNJI, MURATA, YOSHIAKI, NHK SPRING CO., LTD., TAKAZAWA, SYUNJI
Application year: 1999
Main classification: B60R21
IPC codes: B60N2, B60R21