Method of Folding Away Air Bag for Passenger Seat

The present invention relates to an air bag which is installed in front of a front passenger seat in an automobile and inflates automatically in an accident to protect the passenger and, more particularly, to a method of folding away this air bag when an air bag device including this bag is assembled.

In this kind of air bag device for a front passenger seat, an air bag and an inflator are mounted to a retainer case such as a container. Also, a modular cover is mounted to the case so as to cover the bag. In case of an accident, the inflator operates to cause the air bag to inflate. Then, the modular cover is pushed by the inflating air bag and begins to open on the side of the passenger compartment. The air bag inflates greatly toward the passenger compartment to protect the passenger.

This modular cover is provided with a tear start line or bend start line. When the inflator operates, the modular cover is pushed by the air bag and tears or bends along the start line. Then, the cover begins to open on the side of the car interior.

When the air bag of the air bag device for a front passenger seat is expanded on a plane, each longer side portion swells outwardly in an arc. Therefore, when the air bag is folded away, the swelling longer side portions are not neatly folded away. This creates wasteful space inside the case, or it is difficult to insert the bag into the case.

It is an object of the present invention to provide a method of folding an air bag into a boxlike form in such a way that the folded bag can be easily inserted into a case, such as a container or small casing, which holds the air bag.

It is another object of the invention to provide a method of folding away an air bag inside a case without creating any wasteful space in it to thereby permit the case to be reduced in size, thus making the air bag device compact.

It is a further object of the invention to provide a method of folding an air bag into zig-zag shape such that the bag can be smoothly inflated.

The above objects are achieved in accordance with the teachings of the invention by a method of folding away an air bag installed in front of the front passenger seat of an automobile, the air bag having outwardly swelling longer side portions, said method comprising the steps of: folding the longer side portions inwardly of the air bag to straighten out both sides of the air bag and making the width of shorter side portions perpendicular to the longer side portions slightly less than the width of an air bag case; folding the air bag into zig-zag shape along the straightened both sides to create folds at right angles to the straightened both sides; and inserting the folded air bag into the air bag case.

The outwardly swelling longer side portions are folded inwardly of the air bag to straighten both sides of the bag as described above. Therefore, when the bag has been folded away, both of the longer sides of the bag are linear or rectilinear. Hence, the bag can be neatly folded into a boxlike form.

FIG. 1 is a perspective view of an air bag;

FIG. 2 is a plan view of the air bag shown in FIG. 1;

FIGS. 3A and 3B are a plan view and a perspective view, respectively, of the air bag shown in FIG. 1, for illustrating the manner in which the bag is folded away;

FIG. 4 is a cross section taken on line of IV--IV of FIG. 3A;

FIGS. 5, 6, and 7 are side elevations of the air bag shown in FIGS. 1-4, for illustrating the manner in which the bag is folded away;

FIG. 8A is a perspective view of an air bag device;

FIG. 8B is a perspective view of the air bag device shown in FIG. 8A, and in which the air bag has been inflated;

FIG. 9 is a cross section taken on line IX--IX of FIG. 8A;

FIG. 10 is an exploded perspective view of the air bag device shown in FIGS. 8A, 8B, 9;

FIGS. 11A, 11B, and 11C are cross sections of an air bag, for illustrating other methods of folding away the bag.

Referring to FIG. 1, there are shown a small casing 2 and an air bag 1 that is expanded on a plane. The bag 1 has straight shorter sides lb and swelling curved longer sides 1a. An opening 3 is formed in the center of the surface of the bag 1 which is on the opposite side of the passenger, to introduce gas from an inflator. The bag 1 is also provided with vent holes 4 which permit the gas to escape from the bag to mitigate the shock when the passenger collides against the inflating bag. Rivet holes 5 are formed to mount the casing to the bag 1. The dotted line in FIG. 1 indicates a line of perforation. The bottom surface of the casing 2 is provided with holes 6 to allow passage of gas from the inflator.

When the air bag 1 should be inserted into the small casing 2, the bag is first expanded on a plane while the casing 2 is coupled to the fringes of the opening 3 as shown in FIG. 2. Then, as shown in FIGS. 3A, 3B, and 4, the longer sides 1a and their surroundings are folded inwardly of the air bag 1 to make the width of the bag 1 uniform so that it is somewhat less than the width of the casing 2. FIG. 4 is a cross section taken on line IV--IV of FIG. 3A. Then, as shown in FIG. 5 that is a side elevation taken from the direction indicated by the line V--V of FIG. 3A, the air bag 1 is folded many times into zig-zag shape along the longer sides la in such a way that folds 7 are formed perpendicularly to the straight longer sides 1a. That is, the bag is bent in alternate directions. As shown in FIG. 6, the slips formed between the successive folds are brought into contact with each other, pushed in the direction indicated by the arrow B, and compressed. Subsequently, the air bag 1 is pushed downward as viewed in FIG. 6 and inserted into the casing 2 as shown in FIG. 7. The bag 1 may be so enclosed in the casing that the shorter sides 1b are located around the center of the casing 2. Also, the bag 1 may be enclosed in the casing such that the shorter sides 1b extend along the outer surface 2a of the casing 2.

In this method of folding away the air bag, it can be folded into a boxlike form. This facilitates inserting the folded bag 1 into the casing 2 which holds the bag 1. Also, no wasteful space is created inside the casing 2. This permits miniaturization of the casing and makes it possible to render the air bag device compact. Additionally, the bag 1 can be expanded smoothly, because it is folded into zig-zag shape.

The air bag device assembled by this method is shown in FIGS. 8A, 8B, 9, 10, where the device is generally indicated by reference numeral 10. A modular cover 14 is mounted to the front surface of a container 12. The aforementioned inflator, indicated by 16, is rigidly fixed inside the container 12. The small casing 2 is inserted in the container 12 while the air bag is folded. The casing 2 is provided with the holes 6. Gas released from the inflator 16 passes through the holes 6 and inflates the air bag 1. The casing 2 has a flange 20a to which the fringes of the opening in the air bag 1 are secured.

The container 12 takes a boxlike form. A frame 22 of L-shaped cross section is mounted at the inner fringes of the opening on the front side of the container 12. The flange 20a of the casing 2 and the fringes of the opening 3 in the air bag 1 are mounted to the rear side of the frame 22 with rivets 24.

A masking cloth 18b is stretched over the front surface of the air bag 1 and located between the bag 1 and the modular cover 14 to prevent the bag 1 from coming into direct contact with the cover 14.

The modular cover 14 comprises a body portion 14a that is sized to cover the opening in the front surface of the casing 12, an upper flange 14b extending rearward from the upper side of the body portion 14a, and a lower flange 14c extending rearward from the lower side of the body portion 14a. Ribs 14d are formed on the rear surface of the body portion 14a. The side surfaces of the body portion 14a are provided with grooves 14e to permit the body portion 14a to be unfolded easily. Slits 32 are formed in the lower flange 14c of the modular cover 14. Rivets 38 are engaged in the slits 32 to anchor the cover 14 to the casing 12. When pressure acting in the forward direction is produced inside the bag, the cover 14 is disengaged from the casing 12.

In the operation of the air bag device 10 constructed as described above, when the inflator 16 operates, the air bag 1 is inflated. The resulting pressure pushes the modular cover 14, moving the lower half of the cover 14 forwardly. The cover 14 is still subjected to the inflating force of the bag 1. The cover 14 is bent along the grooves 14e and begins to be swung open forward. As shown in FIG. 8B, the air bag 1 is unfolded inside the car interior to protect the passenger.

In the above example, the modular cover 14 is designed to be bent along the grooves 14e. Obviously, the invention can be applied to an air bag device in which the modular cover is torn up and opens on the side of the car interior when the air bag inflates.

In the above example, the air bag is enclosed in the casing. It is also possible to directly insert the air bag in the container.

FIGS. 11A, 11B, and 11C are cross sections illustrating other methods of folding away an air bag and inserting it into the casing 2. As shown in these figures, various methods are available to insert the air bag into the casing 2 after folding the bag in alternate directions. The invention is not limited to the method described in connection with FIGS. 3A-7.