Air Bag for Vehicle Safety Device

1. Field of the Invention

This invention relates to a vehicle safety air bag device having a folded air bag which is inflated and expands in a vehicle interior so as to protect an occupant of the vehicle against injuries during front-end collisions. Additionally, the present invention relates to a particular method of folding the air bag used in such a device.

2. Description of Related Art

In recent years, safety air bags have been installed in vehicles in order to protect occupants of the vehicles, such as a driver and a passenger seated in front seats, against injuries during a collision. For protecting an occupant of the front passenger seat, the safety air bag is typically installed behind a dashboard in front of the passenger seat of the vehicle. An inflater or gas generator generates a pressurized inert gas, and inflates and expands the air bag in the vehicle interior or compartment so as to act as a cushion on the occupant.

It is important to complete inflation and expansion of an air bag rapidly so as to provide sufficiently swift contact between the air bag and the occupant during a collision in order for the occupant to be positively restricted from moving by the inflated air bag.

Because occupants of a front passenger seat move around and vary their postures much more often than occupants of a front driver seat, a passenger seat side air bag is designed to have an inflated volume or size which is almost three times as large as the inflated volume or size of a driver seat side air bag. Therefore, a passenger seat side air bag needs a longer inflation time than does the driver seat side air bag. For this reason, an occupant of the passenger seat will often be contacted by an expanding air bag at a later time than that at which an occupant of the driver seat is contacted by the driver seat side air bag.

In order for the passenger seat side air bag to be rapidly inflated and expanded in a short time, it is possible to increase pressure of the gas supplied into the air bag. However, providing a gas under increased pressure causes the passenger seat side air bag to apply a great impact against the occupant of the front passenger seat.

It is, therefore, a primary object of the present invention to provide a vehicle safety air bag device in which an air bag can be inflated and expanded rapidly in a short time.

It is another object of the present invention to provide a useful method of folding an air bag which can be inflated and expanded rapidly in a short time.

The present invention aims to provide an air bag for a vehicle safety air bag device, having a particular folded structure, which can be inflated by pressurized gas generated by a gas generator and expanded or deployed in a lengthwise direction of the air bag. By using the particular folded structure, an occupant can be contacted by the inflating air bag more rapidly than if the air bag were to be deployed, as is conventional, in a transverse direction of the air bag.

The safety air bag device includes an air bag container or housing, with an opening formed in a vehicle dash panel or in an instrument panel, and an air bag installed in the housing. When inflated, the air bag is expanded through the opening and into the vehicle interior so that the width of the air bag is larger than a transverse width of the opening. The air bag is folded first into a plurality of pleat-folds, in zigzag fashion, at opposite side portions of the air bag. Then, the air bag is folded into a plurality of pleat-folds, in zigzag fashion, from a rear end, remote from the housing, to a front end of the air bag. A pleat-fold in the side portion of the air bag extends, in a lengthwise direction, from the front end to the rear end of the air bag. The air bag, when deflated so that the lengthwise pleat-folds are folded, has a width which is reduced so as to be as small as a transverse width of the opening for the air bag in the dash or instrument panel. When the air bag, thus folded and installed in the housing, is inflated by a pressurized gas generated by the gas generator upon a collision of the automotive vehicle, it is expanded or deployed in the lengthwise direction before it is expanded or deployed in the transverse direction. The air bag thus expands initially toward the occupant at the beginning of expansion or deployment, so that the occupant is quickly contacted by the expanding air bag upon the occurrence of a collision.

The above and other objects and features of the present invention will be apparent from the following description of a preferred embodiment thereof when considered in conjunction with the associated drawings, in which:

FIG. 1 is a perspective view showing the appearance of an essential part of a dash panel of a vehicle in which a safety air bag device is installed;

FIG. 2 is a cross-sectional view of FIG. 1, as seen along section line II--II, which shows a vehicle safety air bag device in accordance with a preferred embodiment of the present invention;

FIGS. 3A-3D are illustrations showing the manner in which the air bag is folded according to the present invention;

FIGS. 4A and 4B are illustrations showing expansion of an air bag which has been folded in the manner illustrated in FIGS. 3A-3D;

FIG. 5 is a cross-sectional view of an air bag folded in a conventional manner; and

FIGS. 6A and 6B are illustrations showing expansion of an air bag which has been folded in the manner shown in FIG. 5.

Referring to the drawings in detail and, in particular, to FIGS. 1 and 2, a safety air bag unit 10 is shown as being mounted in a vehicle dashboard or dash panel 12 by a bracket 22. The safety air bag unit 10 includes a container or housing 16, installed behind the vehicle dash panel 12, and a lid 20, having an outer surface with a profile matching the outer profile of the vehicle dash panel 12. The lid 20 is constructed to cover an opening 16a in the vehicle dash panel 12. When the safety air bag unit 10 is installed in the vehicle, the lid 20 is located in the opening 16a of the vehicle dash panel 12 and forms a part of the vehicle dash panel 12. The lid 20 comprises upper and lower outer walls 20a and 20b and an inner wall 20c connecting the upper and lower outer walls 20a and 20b together. The inner wall 20c has a "parting configuration" formed by a score line or groove 21 provided on its outside surface. The groove 21 is V-shaped, and concentrates stresses applied to the inner wall 20c so that the lid 20 separates into a pair of, or upper and lower, flaps when pressure is applied to the inside surface of the inner wall 20c. Consequently, the lid 20 is separated into upper and lower lid portions. The housing 16 encloses a folded air bag 14 and an inflater or gas generator 18.

As shown in FIGS. 3A-3D, the manner in which the air bag 14 is folded is designed, in accordance with the principles of the present invention, so as to provide a plurality of pleat-folds 14a extending in a lengthwise direction of the air bag 14 in each side portion of the air bag 14. The provision of pleat-folds 14a reduces the width of the air bag 14 so that it is smaller than the transverse width of an opening 16a in a housing 16 when the air bag 14 is deflated and flattened, as FIGS. 3A and 3B show. The flattened air bag 14 is then further folded, from the rear end of the air bag 14, remote from the housing 16, to the front end of the air bag 14, into a plurality of pleat-folds 14b extending in a transverse direction of the air bag 14, as FIGS. 3C and 3D show. The completely folded air bag 14 is placed into the housing 16.

When a collision occurs, the gas generator 18 is activated by a collision sensor (not shown), which may be of any type well known in the art, and an inert gas is rapidly directed, under pressure, into the air bag 14. This forces the air bag 14 through the opening 16a and toward the vehicle dash panel 12 so that it applies pressure to the inside of the lid 20. When such pressure is applied to the lid 20, the V-shaped groove 21 enables the lid 20 to separate into upper and lower lid portions to allow the air bag 14 to expand into the vehicle compartment.

Since the air bag 14 is folded into a plurality of folds in both its direction of thickness and in its lengthwise direction, the air bag 14 is expanded first in the lengthwise direction, with its width kept almost equal to the transverse width of the opening 16a of the housing 16, as shown in FIG. 4A. The air bag 14 is then expanded in the direction of its width so as to complete inflation, as shown in FIG. 4B. The expansion of the air bag 14, therefore, takes place first in a direction toward a passenger seat occupant so that the occupant is contacted by the expanding air bag 14. In other words, the air bag expands first in the lengthwise direction, and then in its direction of width. Inflation of the air bag 14 sufficiently to provide contact of the air bag with the passenger seat occupant, therefore, can be effected in a shorter time than previously possible without any increase in gas pressure.

The advantage of having an air bag 14 folded in the manner described above will be more clearly understood after considering an air bag 4 folded in a conventional manner as shown in FIG. 5. The known air bag 4 is first folded so as to provide upper and lower side folds 4a, which are relatively great in length, when the safety bag 4 is deflated. The air bag 4 is then flattened in a direction of its thickness and, after folding each side fold 4a into a plurality of folds 4b, the air bag 4 is folded, in its lengthwise direction, into a plurality of folds. Each side fold 4a has a large elasticity, which tends to force the fold 4a to restore itself to its expanded state. Consequently, the air bag 4a, even though it is folded into a plurality of folds in the lengthwise direction, expands in both its transverse direction and in its lengthwise direction toward the occupant simultaneously when it is inflated. Such is shown in FIGS. 6A and 6B. Therefore, it is difficult to provide contact of the air bag 4 with the occupant in an acceptably short time during expansion of the known air bag 4.

It is to be understood that although the present invention has been described in detail with respect to a preferred embodiment thereof, various other embodiments and variants may occur to those skilled in the art. All of these other embodiments and variants which fall within the scope and spirit of the invention are intended to be covered by the following claims.