AIR-BAGGED SEAT

Abstract: An air-bagged seat (20) comprises an air bag module (30) in a side portion (22a) of a seat back (22). The air bag module (30) includes a side air bag (32) that mainly spreads out forward in case of a collision of a vehicle. A cover member (25) for covering a side portion (22a) is formed by sewing up a seat-back front cover element (25a) cut in a given shape and a side cover element (25b) at a sewing portion (40), and thread in the sewing portion (40) is adapted to be broken when the air bag unfolds. Mark portions (50) for positioning for sewing operation are formed on edge portions (49) of the cover elements (25a, 25b) at the sewing portion (40). Each mark portion (50) has a projecting shape, such as the shape of a triangle.

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 having a built-in air bag module in its seat back. Background Art An air bag system that is mounted in a vehicle such as an automobile is designed so that an air bag is caused instantaneously to inflate by an inflator in case of a collision of the vehicle, whereby a user can be restrained from undergoing a second collision with some interior members. To cope with a head-on collision, the air bag system may be 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. In a vehicle seat that is furnished with a side air bag system, an inflator is incorporated in one of two opposite side portions of the seat back that is nearer to a door. This inflator is actuated in response to a signal that is delivered by a sensor when the vehicle is subjected to a side impact. The air bag can be inflated with gas that is generated by the inflator. The seat back includes a frame, pad, cover member, etc. The cover member of the air bag storage portion is composed of a seat-back front cover element 1, a side cover element, etc. As the air bag unfolds, thread in a sewing portion between the seat- back front cover element and the side cover element is broken by pressure that acts thereon from inside the cover member. The air bag bulges ahead of the seat back through the broken portion. The air bag unfolds into a shape such that it can protect the flank, temple, etc. of the user. For example, a conventional side cover element 1 shown in FIG. 6 is formed of artificial leather such as vinyl leather, natural leather, cloth such as woven fabric, or knit fabric that is cut in a given shape. The side cover element 1 is sewn together with a seat- back front cover element (not shown). Mark portions 2 for use as positioning means for sewing operation are provided on the respective edge portions of the side cover element 1 and the cover element to be sewn together therewith. The mark portions 2 are referred to also as "spots." Each conventional mark portion 2 is in the form of a V-shaped notch or is recessed. If the mark portions 2 are recessed, as described above, a built-in air bag 3 that spreads out forward (or in the direction indicated by arrow F) may possibly be broken at a sewing portion that is influenced by the air bag's unfolding, starting at any of the mark portions 2, as indicated by dashed line C in FIG. 6, for example. If the cover elements break themselves in this manner, force cannot easily acts on thread in a proper expected portion to be broken, that is, a sewing portion la at which the seat-back front cover element and the side cover element 1 are sewn up. Possibly, in this case, any other portion than the sewing portion la, e.g., the side cover element 1, may tear as the air bag unfolds, thus lowering the unfolding performance of the air bag. Accordingly, the object of the present invention is to provide an air-bagged seat designed so that a predetermined portion can be broken securely when an air bag incorporated in a seat back unfolds, thus ensuring proper unfolding performance. Disclosure of Invention According to the present invention, there is provided an air-bagged seat comprising an air bag located in a seat back and adapted to be unfolded by means of an inflator, in which a cover member for covering an air bag storage portion is formed by sewing up a plurality of cut cover elements, and mark portions for positioning the cover elements to be sewn up are provided in corresponding positions on edges portions of the cover elements to be sewn together, the mark portions having a projecting shape, such as the shape of a triangle, each. In the air-bagged seat of the present invention, the inflator is actuated so that gas is jetted out to inflate the air bag when subjected to force of impact. The resulting pressure acts from inside the cover member. According to the present invention, the positioning mark portions at a sewing portion between the cover elements that constitute the cover member, unlike the conventional recessed ones, are projecting, so that there is no possibility of the mark portions becoming starting points of rupture when the air bag unfolds. Accordingly, sewing thread is broken if the predetermined sewing portion is subjected to force that is generated when the air bag unfolds. Thus, a cover element, such as a side cover element, can be restrained from breaking itself. The air bag of the present invention unfolds steadily in a regular direction, so that the shock of a second collision between a user and interior members can be eased. 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 the gas to be used for inflation is not limited to nitrogen or air. 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 embodi- ments given below, serve to explain the principles of the invention. FIG. 1 is a plan view of a cover element used in a cover member of an air-bagged seat according to an embodiment of this invention; FIG. 2 is an enlarged plan view showing part of the cover element shown in FIG. 1; FIG. 3 is a perspective view of the air-bagged seat using the cover element shown in FIG. 1; FIG. 4 is a cross-sectional view of part of the air-bagged seat shown in FIG. 3; FIG. 5 is a perspective view of the air-bagged seat shown in FIG. 3 with its air bag unfolded; and FIG. 6 is a plan view of a cover element for a cover member of a conventional air-bagged seat. Best Mode of Carrying Out the Invention An embodiment of this invention will now be described with reference to FIGS. 1 to 5. A side-air-bagged seat 20 shown in FIG. 3, which is applied to a front seat of an automobile, is provided with a seat cushion 21 and a seat back 22. The seat back 22, part of which is shown in FIG. 4, 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. A bracket 28 is fixed to the lateral of the seat back frame 23 by welding or the like. An air bag module 30, which constitutes a side air bag system, is incorporated in one of two opposite side portions 22a and 22b of the seat back 22, that is, the side portion 22a that is nearer to a door. The air bag module 30 is composed of a casing 31 fixed to the bracket 28 of the seat back frame 23, 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 functions also as a guide member for regulating the direction in which the inflator gas is jetted out. The inflator 33 is connected with an ignition system, which includes a sensor for detecting a side impact of a vehicle, an electric power source (not shown), etc. The cover member 25 is formed by cutting a cover element of artificial or natural leather or woven fabric into a given shape and sewing it. An example of artificial leather is obtained by coating the outer surface of knitted fabric for use as a back fabric base with an elastic material such as an elastomer layer. The cover member 25, which covers the side portion 22a that functions as an air bag storage portion, includes a seat-back front cover element 25a that constitutes the front face of the side portion 22a, a side cover element 25b that constitutes the side face of the side portion 22a, etc. These cover elements 25a and 25b are sewn together at a sewing portion 40 by means of sewing thread 41. These cover elements 25a and 25b are obtained by cutting a rolled cover material into a desired shape. In the side cover element 25b, as is typically shown in FIG. 1, projecting mark portions (spots) 50 are provided on edge portions 49 of the seat-back front cover element 25a and the side cover element 25b. These mark portions 50 are cut so as to project triangularly from the respective edge portions 49 of the seat-back front cover element 25a and the side cover element 25b as the cover elements 25a and 25b are cut from the rolled cover material. These mark portions 50 are located in positions such that they meet one another when the two cover elements 25a and 25b sewn up. Thus, these mark portions 50 are used to position the cover elements 25a and 25b as they are sewn up. As shown in FIG. 2, for example, each mark portion 50 is substantially in the shape of an isosceles triangle. For example, each mark portion 50 has a height H of 4 mm and a width of 5 mm. In sewing operation, the cover elements 25a and 25b are aligned with each other with their respective mark portions 50 as guides as the cover elements 25a and 25b are sewn together at the sewing portion 40 by means of the sewing thread 41. The mark portions 50 are used at least for that part of the sewing portion 40 which is influenced by unfolding action of the air bag 32. Either conventional recessed mark portions (shaped like the mark portions 2 shown in FIG. 6) or the projecting mark portions 50 may be used for other parts of the sewing portion. The following is a description of the operation of the side-air-bagged seat 20. 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 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 ejected gas, the air bag 32 unfolds ahead of the casing 31. Pressure from this unfolding action acts on the sewing portion 40 between the seat-back front cover element 25a and the side cover element 25b. The cover member 25 uses the cover elements 25a and 25b that are provided with the projecting mark portions 50. When the air bag 32 unfolds, therefore, the mark portions 50 of the cover elements 25a and 25b can avoid becoming starting points of rupture, and force to break the sewing portion 40 acts directly on the sewing thread 41. Accordingly, the sewing thread 41 in the sewing portion 40 breaks without fail, whereupon the air bag 32 mainly spreads out forward (or in the direction indicated by arrow F) and upward from the broken sewing portion 40, with respect to the seat back 22, as shown in FIG. 5. The air bag 32 thus unfolded is located in a space between the flank of a seated user's body and an inner side wall of the vehicle body, whereby the shock of a second collision between the user and the inner side wall of the vehicle body can be eased. In carrying out this invention, projecting mark portions 50 similar to the ones according to the aforementioned embodiment may be used for the other parts of the sewing portion than the seat-back front cover element 25a and the side cover element 25b. In short, according to the present invention, an expected object of this invention can be achieved by applying the projecting mark portions to that part of the sewing portion which is influenced by the air bag's unfolding action. It is to be understood that this invention is not limited to the embodiment described above, as regards the location and number of the mark portions 50 or the specific shape of the mark portions 50, and that various changes may be effected therein without departing from the spirit of the invention. The cover member 25 for covering the side portion 22a for use as an air bag storage portion may be a combination of the seat-back front cover element 25a, side cover element 25b, and some other cover elements. Industrial Applicability The air-bagged seat according to this invention is designed so that force from unfolding action of the air bag can be applied to a predetermined portion such as a sewing portion to be broken, so that the predetermined portion can be broken securely. According to the air-bagged seat of this invention, the unfolding direction of the air bag is stable, and proper unfolding performance can be displayed. 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 L A I M S 1. In an air-bagged seat having an air bag (32) located in a seat back (22) and adapted to be unfolded by means of an inflator (33), the air-bagged seat characterized in that: a cover member (25) for covering an air bag storage portion (22a) of said seat back (22) is formed by sewing up a plurality of cut cover elements (25a, 25b); and mark portions (50) for positioning the cover elements (25a, 25b) to be sewn up are provided in corresponding positions on edges portions (49) of the cover elements (25a, 25b) to be sewn together, the mark portions (50) having a projecting shape each. 2. An air-bagged seat according to claim 1, wherein each said mark portion (50) is substantially in the shape of an isosceles triangle. 3. An air-bagged seat according to claim 1, wherein said air bag storage portion (22a) is a side portion (22a) of a seat, said cover member (25) for covering the side portion (22a) includes a seat-back front cover element (25a) constituting the front face of the side portion (22a) and a side cover element (25b) constituting the side face of the side portion (22a), and said mark portions (50) are provided on the edge portions (49) of the cover elements (25a, 25b). 4. An air-bagged seat according to claim 3, wherein said air bag (32) is a side air bag adapted mainly to spread out forward and upward in case of a collision of a vehicle.

Inventors: WATANABE TOSHIYASU, WATANABE, TOSHIYASU
Applicants: NHK SPRING CO LTD, WATANABE TOSHIYASU, NHK SPRING CO., LTD., WATANABE, TOSHIYASU
Application year: 1999
Main classification: B60R21
IPC codes: B60N2, B60R21