Air bag system

By disposing external straps 36 to 38 which are passed through a tubular member 34 which passes through an air bag 21 in a tunnel-like fashion to open in side surfaces of the air bag 21 are disposed on an outer circumference of the air bag 21 and controlling the deployment shape of the air bag 21 by the external straps 36 to 38 so disposed, the occupant restraining performance of the air bag can effectively be enhanced.

BACKGROUND OF THE INVENTION

The present invention relates to an air bag system in which a folded air bag and an inflator are supported on a retainer, so that the air bag is inflated to be deployed into a passenger compartment of a vehicle by a gas produced by the inflator at the time of collision.

While an air bag which deploys into the passenger compartment of a vehicle to restrain an occupant at the time of collision of the vehicle is farmed by sewing a plurality of base fabrics, it is difficult to control the deployment shape of the air bag as desired only by devising the shapes of the base fabrics. To cope with this, conventionally, a strap for connecting the base fabrics together or a strap for connecting the base fabric to a retainer is provided in the interior of the air bag, whereby the deployment shape of the air bag is controlled by allowing the tension of the strap to be applied to the base fabrics at the time of deployment of the air bag (for example, refer to JP-A-5-178146).

However, since a job of installing the strap in the interior of the air bag is troublesome, the processing costs are increased, and since the tension of the strap is applied only to the connecting portion with the base fabric, it is difficult to control the deployment shape of the air bag as desired.

SUMMARY OF THE INVENTION

The invention is made to address these situations, and an object thereof is to enable a freer control of the deployment shape of the air bag with a simple construction.

With a view to attaining the object, according to a first aspect of the invention, there is proposed an air bag system in which a folded air bag and an inflator are supported on a retainer, so that the air bag is inflated to be deployed into a passenger compartment of a vehicle by a gas produced by the inflator at the time of collision, wherein a through hole is formed which passes through the air bag in a tunnel-like fashion to open in both side surfaces of the air bag, so that a deployment shape of the air bag is controlled by an external strap which passes through the through hole to be disposed on an outer circumference of the air bag.

According to the construction that is described above, since the external strap which is passed through the through hole which passes through the air bag in the tunnel-like fashion to open in the side surfaces of the air bag is disposed on the outer circumference of the air bag, the deployment shape of the air bag can be controlled by the external strap so as to enhance the occupant restraining performance of the air bag effectively. In particular, by disposing the external strap on the external portion of the air bag, not only can the number of man-hours for processing be reduced when compared with a case where the strap is disposed in the interior of the air bag but also the deployment shape of the air bag can be controlled more freely due to the external strap being brought into not a point contact but a line or surface contact with the air bag, and moreover, the behaviors of the air bag in the deployment process can be stabilized.

Note that a tubular member34in embodiments corresponds to the through hole in the invention and first to fourth external straps correspond to the external strap36to39in the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Modes for carrying out the invention will be described below based on embodiments of the invention illustrated in the accompanying drawings.

FIGS. 1 to 6illustrate a first embodiment of the invention, in whichFIG. 1is a perspective view of a front part of a passenger compartment of an automobile,FIG. 2is an enlarged cross-sectional view taken along the line2—2inFIG. 1,FIG. 3is an exploded perspective view of an air bag system,FIG. 4is a perspective view of an air bag in a deployed state,FIG. 5is a cross-sectional view taken along the line5—5inFIG. 4, andFIG. 6is an exploded perspective view of the air bag.

As shown inFIG. 1, an air bag system13for a front passenger seat11is provided at an upper portion in a dashboard12disposed in front of the front passenger seat11.

As shown inFIGS. 2 and 3, a retainer16forte air bag system13is fixed to support portions14awhich extend downwardly from a lid14fixed to the sides of an opening formed in a top surface of the dashboard12. The retainer16includes an upper retainer18and a lower retainer19which are fixed together with a plurality of bolts17, and the upper retainer18is fixed to the support portions14aof the lid14with a plurality of bolts20.

A folded air bag21is accommodated in a space surrounded by the upper retainer18and the lid14in a state in which top, front and rear sides of the air bag21are encompassed by a fabric packing flap22. The packing flap22is sewn23,23to the air bag21along front and rear edges thereof, and fixing portions22a,22aat a lower end of the packing flap22and fixing portions21a,21aat a lower end of the air bag21are held between the upper retainer18and the lower retainer19and are then fastened together to the upper and lower retainers with the bolts17. Brittle portions22care formed at a rear portion on the top surface of the packing flap22via slits22b.

A thin tearable line14badapted to be broken when the air bag21inflates is formed in an H-shape in the lid14, and two thin hinge lines14c,14cadapted to be bent in association with the breakage of the tearable line14bare also formed in the lid. A cylindrical inflator25is installed at a bottom portion of the lower retainer19via a pair of mounting brackets24,24.

As is clear fromFIGS. 4 to 6, the air bag21is such as to be formed into a bag-like shape by sewing33,33together a single main base fabric31and two side base fabrics32,32which are disposed on left and right sides of the main base fabric31, and top, rear (facing an occupant) and bottom surfaces of the air bag21in a deployed state are constituted by the main base fabric31, whereas left and right surfaces of the air bag21in such a state are constituted by the side base fabrics32,32. A tubular member34formed by sewing a fabric into a tubular configuration is sewn35,35at both ends thereof to peripheries of openings32a,32awhich are formed in centers of the left and right side base fabrics32,32, respectively. Consequently, the left and right side surfaces of the air bag21are allowed to communicate in a tunnel-like fashion by the tubular member34.

Three belt-like external straps36,37,38are passed through the interior of the tubular member34, respectively, and ends of the respective straps are sewn together so that the respective straps are formed into an annular-shape. The first external strap36is disposed so as to surround the air bag21from the left and right surfaces to the top surface thereof, the second external strap37is disposed to surround the air bag21from the left and right surfaces to the bottom surface thereof, and the third strap38is disposed to surround the air bag21from the left and right surfaces to the rear surface thereof. As this occurs, it is desirable to fix the external straps36,37,38to the air bag21at a plurality of locations so that the external straps36,37,38are not deviated relative to their proper positions on the air bag21.

Thus, when an acceleration which reaches or exceeds a predetermined value is detected at the time of collision of the vehicle, the inflator25is ignited, and the folded air bag21starts to be inflated by a gas produced by the inflator25. When the packing flap22receives a pressure applied by the inflating air bag21, the brittle portions22cin the packing flap22break, and furthermore, when the lid14receives the pressure applied by the inflating air bag21, the thin tearable lines14b break and the lid14opens along the hinge lines14c,14c, whereby the air bag21is allowed to deploy into the passenger compartment from an opening so formed in the lid14so as to restrain the occupant.

While the air bag21in the folded state is easy to be disrupted in shape by an external force, the shape of the air bag21can be stabilized by being encompassed by the packing flap22, whereby not only can the disruption in shape of the air bag21be prevented when the air bag21is carried as a single unit or is installed in the interior of the retainer16but also the handling property thereof can be enhanced.

Then, when the air bag21is allowed to deploy into the passenger compartment, since the three external straps36,37,38which are in abutment with the outer circumferential surface of the air bag21produce a tension to thereby restrict the inflation of the air bag21, the deployment shape of the air bag21can be controlled as required by altering the dimensions and mounting positions of the external straps36,37,38.

In particular, since the external straps36,37,38are disposed at the external portions of the air bag21, when compared with internal straps which are disposed in the interior of the air bag21, the number of man-hours required to mount the external straps can be decreased, and moreover, since the external straps36,37,38are brought into not a point contact but a line or surface contact with the air bag21, the deployment shape of the air bag21can be controlled more freely. In addition, the behaviors of the air bag21in the deployment process can be stabilized so as to enable a smooth deployment by pressing the outer circumferential surface of the air bag21in the deployment process by the external straps36,37,38.

The external straps are arranged arbitrarily, and for example, as illustrated in a second embodiment shown inFIG. 7, the third external strap38of the first to third straps36to38in the first embodiment is removed, and instead, a fourth external strap39may be arranged in such a manner as to pass through the interior of the tubular member34so as to cover the air bag21from the left and right surfaces to the front surface thereof.

In addition, while the air bag21in the first and second embodiments is provided with the external straps36to38only, an internal strap or straps may be used in parallel with the external straps.

For example, in a third embodiment illustrated inFIG. 8, in addition to the external straps36,37in the first and second embodiments, a rear end portion of the main base fabric31of the air bag21is connected to the retainer16by two internal straps40,40. The two internal straps40,40are disposed above and below the tubular member34in such a manner as to bypass it so that no interference between the straps and the tubular member occurs. In addition, a fourth embodiment illustrated inFIG. 9is such that the second external strap37in the third embodiment is removed.

Thus, even if the internal straps are used together with the external straps, when compared with an air bag employing only an internal strap or straps, not only can the control property of the deployment shape of the air bag21be enhanced but also the stability in behaviors of the air bag21at the time of deployment can be enhanced, which can contribute to the reduction in production costs.

Thus, while the embodiments of the invention are described in detail heretofore, the invention can be modified variously with respect to its design without departing from the spirit and scope of the invention.

For example, while the air bag system13for the front passenger seat is described in the embodiments, the invention can be applied to an air bag system for use for a driver's seat or at any locations within the passenger compartment of the vehicle.

As is described above, according to the first aspect of the invention, since the external straps which are passed through the through hole which passes through the air bag in the tunnel-like fashion to open in the side surfaces of the air bag are disposed on the outer circumference of the air bag, the deployment shape of the air bag can be controlled by the external strap so as to enhance the occupant restraining performance of the air bag effectively. In particular, by disposing the external straps on the external portion of the air bag, not only can the number of man-hours for processing be reduced when compared with a case where the straps are disposed in the interior of the air bag but also the deployment shape of the air bag can be controlled more freely due to the external straps being brought into not a point contact but a line or surface contact with the air bag, and moreover, the behaviors of the air bag in the deployment process can be stabilized.