MODULE COVER OF AIR BAG

Abstract: A module cover of an air bag excellent in appearance and durability, which is provided with one main surface (3), four side peripheral surfaces (2A, 2B, 2C and 2D) each integral with the main surface (3), and tear lines (6) running on only three side peripheral surfaces (2B, 2C and 2D).

Description: TECHNICAL FIELD The present invention relates to a modular cover for use in an air bag assembly and particularly, to such a modular cover which provides for full deployment of an air bag, which has good appearance, and which is durable. BACKGROUND ART As shown in Fig. 4, an air bag assembly is disposed centrally on a vehicle steering wheel 10 to sense impact or deformation upon collision of a vehicle so as to deploy and inflate an air bag. This air bag assembly includes a mounting plate, commonly referred to as a retainer. An inflator and an air bag are mounted to the mounting plate and covered by a modular cover 11. The modular cover 11 is fit over spokes 12 of the steering wheel. The modular cover 11 has tear lines 13 along which the modular cover can be ruptured when the air bag is deployed. The tear lines are in the form of a continuous groove or a semicontinuous groove. The tear lines may alternatively include spaced grooves of greater depth. When the cover has two different layers, a rigid layer and a soft layer, a slit may be formed in the rigid layer so that the cover may be ruptured along a predetermined line. As shown in Fig. 4, the tear lines 13 of the prior art modular cover 11 are formed on a top or main surface 11A and include tear lines 13a, 13b extending vertically along lateral sides of the main surface 11A, and another tear line 13c centrally and laterally of the cover 11. A vertical direction is a direction from an occupant M towards a windshield G, and a lateral direction is the width direction of a vehicle. In this case, the steering wheel is so oriented as to allow the vehicle to run on a straight line. When such a conventional modular cover is molded, sinkmarks may be formed to cause wrinkles around the tear lines 13 on the top or main surface 11A of the modular cover 11. Those wrinkles, if quite visible, may deteriorate the aesthetic appearance of the modular cover. The occupant of a vehicle may rub such wrinkles with his fingers. This causes the tear lines to be repeatedly bent and deformed to reduce the durability of the modular cover 11. A leather may overlie the main surface 11a of the modular cover to provide a high quality modular cover. In such a case, however, the leather may prevent the modular cover 11 to rupture along the tear lines 13. As such, the leather can not be used in the prior art modular cover. US-A-3888508 describes a cover for an air bag device on which the preamble to the main claim of the present invention is based. DISCLOSURE OF THE INVENTION It is an object of the present invention to solve the problems encountered in the prior art and to provide a modular cover for use in an air bag assembly, which is free from any wrinkle on its main surface to provide good appearance, which is not repeatedly bent and deformed and is, thus, durable, and which includes a genuine leather on its main surface, but can be ruptured along tear lines. The present invention provides a modular cover for use in an air bag assembly, the modular cover being generally in the form of a box having an open bottom and a closed top, and having a tear line extending along a part of a peripheral side wall of the modular cover and a part of said peripheral side wall being free of said tear line, said modular cover being characterised by further including a skirt surrounding the peripheral side wall so that a main surface portion of the modular cover with the skirt is opened in the same direction when the modular cover is ruptured along said tear line. With the modular cover of the present invention, the peripheral side wall of the modular cover, rather than the main surface portion is ruptured along the tear line when the air bag assembly is operated. As a result, the entire main surface portion is opened toward one side on which no tear line is formed. According to the present invention, the modular cover has no tear line on its main surface portion. Thus, the main surface portion is free from any wrinkles to provide good appearance. In addition, the tear line of the modular cover is not repeatedly bent and deformed to maintain the durability of the modular cover. Also, according to the present invention, a high quality material such as a genuine leather may be applied to the main surface of the modular cover. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view, partly in section, of a modular cover for an air bag assembly according to one embodiment of the present invention; Fig. 2 is a perspective sectional view taken on the line II-II of Fig. 1; Fig. 3 is a perspective view, partly in section, of an air bag in its inflated condition; and Fig. 4 is a perspective view of the prior art. BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail, by way of example, with reference to the drawings. In Figs. 1 to 3, 10 is a steering wheel, and 12 are spokes. A modular cover 1 is attached to a retainer 18 by means of press plates 14 and rivets 16. As shown in Fig. 3, an inflator 20 and an air bag 22 are also mounted to the retainer 18. The modular cover 1 shown in Figs. 1 to 3 is a box with an open bottom and a closed top and includes a peripheral side wall 2, a main surface portion 3, and a skirt 4 depending from the peripheral edge of the main surface portion 3. The peripheral side wall 2 and the main surface portion 3 are made of synthetic resin. A reinforcing cloth 5 is inserted into the peripheral side wall 2 and the main surface portion 3. This reinforcing cloth 5 is not shown in Fig. 1. The peripheral side wall 2 includes four side wall portions 2A, 2B, 2C and 2D and the modular cover ruptures along tear line 6 extending centrally and circumferentially of three side wall portions 2B, 2C and 2D except the side wall portion 2A adjacent to the windshield G. The reinforcing cloth 5 is embedded in a portion of the modular cover other than that portion where the tear line is formed. The side walls 2B to 2D of the modular cover 1 are ruptured when the air bag assembly is operated. At this time, the main surface portion 3 is not ruptured, but is largely opened toward the side wall 2A in which no tear line extends or toward the windshield G as shown in Fig. 3. The top of the modular cover 1 is thus opened to allow deployment of the air bag 22. A region 26 shown by hatching in Fig. 3 is a section of the cover as ruptured along the tear line 6. As stated above, the tear line 6 is formed on the side wall portions 2B, 2C and 2D, but not on the main surface portion 3 of the modular cover 1. The main surface portion 3 is thus free from any wrinkle to provide good appearance. Additionally, that portion around the tear line is not repeatedly bent and deformed to maintain the durability of the modular cover 1. A high quality material such as a genuine leather may also be applied to the main surface portion 3, but not to cover the tear line 6. Therefore, such a leather does not prevent rupture of the cover along the tear line 6 to allow immediate opening of the modular cover 1. INDUSTRIAL APPLICABILITY As is understood from the foregoing embodiments, the modular cover of the present invention has no tear line on its main surface. The tear line extends circumferentially along the side walls except some part. This design provides good aesthetic appearance and increases the durability of the modular cover. The modular cover can effectively be ruptured and have a high quality material on its main surface.

Claims: A modular cover (1) for use in an air bag assembly, the modular cover being generally in the form of a box having an open bottom and a closed top, and having a tear line (6) extending along a part (2B, 2C, 2D) of a peripheral side wall (2) of the modular cover (1) and a part (2A) of said peripheral side wall being free of said tear line, said modular cover (1) being characterised by further including a skirt (4) surrounding the peripheral side wall (2A, 2B, 2C, 2D) so that a main surface portion (3) of the modular cover and the skirt (4) are opened in the same direction when the modular cover (1) is ruptured along said tear line (6). A modular cover for use in an air bag assembly according to claim 1, wherein said modular cover (1) includes the main surface portion (3) as the closed top, four peripheral side wall portions (2A, 2B, 2C, 2D) extending from the main surface portion (3), and the tear line (6) extending on three (2B, 2C, 2D) of the four peripheral side wall portions (2A, 2B, 2C, 2D). A modular cover for use in an air bag assembly according to either claim 1 or claim 2 wherein said modular cover (1) has portions co-operating with spokes (12) of a steering wheel. A modular cover according to any one preceding claim wherein said skirt (4) depends from the side edges of said main surface portion (3) A modular cover according to any one preceding claim characterised by further including a reinforcing cloth (5) embedded in said main surface portion (3) and part (2A) of said peripheral side wall (2) being fee of said tear line (6).

Inventors: SAKATA YOSHIAKI, SAKATA, YOSHIAKI
Applicants: TAKATA CORP, TAKATA CORPORATION
Application year: 1991
Main classification: B60R21
IPC codes: B60R21