Air Bag Cover Opening Mechanism for Use in Vehicle

1. Field of the Invention

The present invention relates to an air bag cover opening mechanism for use in a vehicle. Description of the Related Art:

A technique concerning a structure for fixing an air bag cover for a passenger seat air bag is disclosed in Japanese Utility Model Application Laid-Open No. 63-111353.

This technique is shown in FIG. 6. The prior art discloses, as shown in FIG. 6, an opening 9 for allowing an unillustrated air bag to jump out therethrough which is provided at a predetermined location in an instrument panel 8 corresponding to a passenger seat. The opening 9 is closed by an air bag cover 2. The air bag cover 2 has an upper end secured rotatably to the instrument panel 8 via a hinge or the like, and a lower end secured to the instrument panel 8 by means of resin-made retainers 3 and bolts 4, 41.

A detailed description will now be given of a specific prior art structure for securing the lower end of the air bag cover 2.

As shown in FIG. 7, the air bag cover 2 has a three-layered structure comprising a metal insert 21, a foamed layer 22, and a surface layer 23. A notched portion 25 to which the retainers 3 is attached is not provided in the foamed layer 22 or the surface layer 23 but is provided only in the insert 21, and a threaded hole 24 is also provided therein.

The retainer 3 is arranged such that two retaining portions 31a, 32a are connected to each other via a thin integral hinge 33, as shown in FIG. 8.

One retaining portion 31a is provided with a slot 34 extending longitudinally from a thicknesswise central portion of one end thereof. Also, a hole 35 is provided in a central portion of the retaining portion 31a in such a manner as to penetrate the two slotted segments thereof. Grooves 36 are respectively formed longitudinally in opposite sides of the other retaining portion 32a, and a hole 37a is provided in a central portion thereof in such a manner as to penetrate the same in the same direction as the hole 35.

As shown in FIG. 8, the retainer 3 is fitted to the notched portion 25 in such a manner that the slot 34 of the retaining portion 31a is received by the innermost portion of the insert 21, while the grooves 36 of the other retainer 32a are received by inner lateral portions of the insert 21 at the notched portion 25. Thus the overall retainer 3 is accommodated in the notched portion 25. Then, one retaining portion 31a is secured to the air bag cover 2 as the screw 41 is inserted into the holes 35, 24 and tightened. Meanwhile, the other retaining portion 32a is superposed on a fixing portion 81 of the instrument panel 8, and is secured to the instrument panel 8 by a bolt 4 inserted into the hole 37a provided in the other retaining portion 32a. As a result, the air bag cover 2 is secured to the instrument panel 8.

With the above-described structure for fixing the air bag cover, since the retainer 3 is closely secured to the air bag cover, even if vibrations are applied to the instrument panel 8 during normal running of the vehicle, the integral hinge 33 does not undergo fatigue. At the time of inflation of the air bag, however, the air bag cover 2 is pressed by a load caused by the inflation of the air bag, with the result that the integral hinge 33 is broken, thereby allowing the air bag cover 2 to be pushed open.

However, with the above-described conventional structure for fixing the air bag cover 2, since the other retaining portion 32a secured to the instrument panel 8 side of the retainer 3 is constantly located at the same position relative to the movement of the air bag cover 2 which is pushed open toward the interior of the vehicle compartment, both a load oriented in the pulling direction and a load oriented in the shearing direction act on the integral hinge 33 which is the breaking portion. Accordingly, the load occurring at the time of the inflation of the air bag is not effectively transmitted to the integral hinge 33 which is the breaking portion of the retainer 3, with the result that there is the possibility that the air bag cover 2 may not be pushed open smoothly.

In view of the above-described circumstances, it is an object of the present invention to provide an air bag cover opening mechanism for smoothly pushing open an air bag cover. The present invention utilizes the load occurring at the time of the inflation of the air bag by converting a load acting on a retainer in a shearing direction to a load acting in a pulling direction.

The air bag cover opening mechanism in accordance with the present invention is used for opening an air bag device. The mechanism comprises air bag case secured to a vehicle body for accommodating an air bar in a folded state. The air bag has an opening in the inflating direction of the air bag. An air bag cover covers the opening provided in the air bag case. One end of the air bag cover is hingably connected to the air bag case via a connecting member. The other end of the air bag cover is secured to the air bag case or the vehicle body via a retainer which is secured rotatably by means of connecting members such that only tensile force acting in the same direction as the direction of the pushing open of the air bag cover is applied thereto.

In accordance with the present invention arranged as described above, at the time of inflation of the air bag, the air bag cover tends to be pushed open with the connecting member securing one end of the air bag cover as a center of rotation, while the air bag is being inflated toward the interior of a vehicle compartment. This movement causes a load oriented in the pulling direction and a load oriented in the shearing direction to be applied to the retainer. However, since the retainer is attached to the air bag case in such a manner as to be rotatable in the same direction as the opening direction of the air bag cover, the retainer, upon application of the load oriented in the shearing direction thereto, rotates in the pulling direction, and the retainer follows the direction in which the air bag cover is pushed open. That is, the load in the shearing direction acting on the retainer causes the retainer to rotate, and the load in the shearing direction is converted to a load oriented in the pulling direction. Accordingly, since only a load oriented in the pulling direction is applied to the retainer, energy at the time of the inflation of the air bag is used effectively to break the retainer, with the result that the air bag cover is pushed open smoothly.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings.

FIG. 1 is a side cross-sectional view of an air bag cover opening mechanism in accordance with the present invention;

FIG. 2 is an overall perspective view of an air bag cover opening mechanism in accordance with the present invention;

FIG. 3 is an enlarged perspective view of a retainer;

FIG. 4 is a partly cutaway perspective view illustrating how the retainer is attached to the air bag cover;

FIG. 5 is a cross-sectional view taken along A--A in FIG. 1;

FIG. 6 is an overall perspective view of a conventional air bag cover opening mechanism;

FIG. 7 is an enlarged exploded perspective view illustrating how the other end of the conventional air bag cover is fixed by means of a retainer; and

FIG. 8 is a cross-sectional view of the conventional retainer and its surrounding portions.

A description will be given of a specific embodiment of the present invention. Those component parts and portions that are identical with those of the conventional art shown in FIGS. 6 to 8 will be denoted by the same reference numerals.

FIGS. 1 to 5 illustrate a preferred embodiment of the present invention. In FIGS. 1 and 2, an air bag 90 in a folded state is accommodated in an air bag case 1. An air bag cover 2 covers an opening which is provided in the air bag case 1 and through which the air bag 90 is adapted to jump out. One end of the air bag cover 2 is rotatably secured to the air bag case 1 via a hinge 6. The other end of the air bag cover 2 is secured to the air bag case 1 via two retainers 3 formed of a resin.

As shown in FIG. 3, the retainer 3 is arranged such that one retaining portion 31 to be secured to the air bag cover 2 and the other retaining portion 32 to be secured to the air bag case 1 are connected to each other via a breaking portion 33, a hole 37 being provided in the other retaining portion 32.

As shown in FIG. 4, the retainer 3 is set in advance in an insert 21 in such a manner that the other retaining portion 32 is inserted into a slit 7 provided in the insert 21 of the air bag cover 2, thereby allowing one retaining portion 31 to be exposed on the interior surface of the insert 21 and the other retaining portion 32 to project from the exterior surface of the insert 21. Then, a foamed layer 22 and a surface layer 23 are formed integrally on the exterior surface of the insert 21, so that the retainer 3 is secured to the air bag cover 2.

A description will now be given of a structure for fixing the air bag cover 2 to air bag case. An upper end of the air bag cover 2 is fixed to the air bag case 1 by hinge 6 formed integrally with the insert 21. Hinge 6 is attached to the air bag case 1 by bolts or the like (see FIGS. 1 and 2). As shown in FIG. 5, a lower end of the air bag cover 2 is fixed to the air bag case 1 as follows. A hole 92 provided in a side wall of the air bag case 1 is aligned with the hole 37 in the retaining portion 32 projecting from the reverse surface of the air bag cover 2. A spacer 5 with a head is inserted from the inner side of the air bag case 1 into the aligned holes 92, 37. Then, a bolt 4 is threaded into an internally threaded hole provided in the spacer 5 so as to secure the other retaining portion 32 with respect to the air bag case 1 via the spacer 5. Since the other retaining portion 32 is secured with respect to the air bag case 1 via the spacer 5, the other retaining portion 32 is rotatable around spacer 5 with respect to the air bag case 1. It should be noted that the spacer 5 having the internally threaded hole also serves as a nut.

With the air bag device having the air bag cover opening mechanism arranged as described above. The inflation of the air bag 90 causes a load to act on the interior surface of the air bag cover 2 and forces the air bag cover toward the interior of the vehicle. Specifically, the load causes the air bag cover 2 to open with the hinge 6 as a center of rotation at the upper end thereof and to advance into the interior of the vehicle compartment. At this time, a load oriented in a shearing direction and a load oriented in a pulling direction act on the retainer 3. However, since the retainer 3 is rotatably secured to the side surface of the air bag case 1, the retainer 3 rotates upward due to the load acting in the shearing direction. Accordingly, only the load oriented in the pulling direction acts on the retainer 3. Since the load at the time of the inflation of the air bag effectively acts on the retainer 3, the breaking portion 33 provided in the retainer 3 is broken smoothly, with the result that the air bag cover 2 is opened smoothly.

Furthermore, in this embodiment arranged as described above, before the air bag device is installed in an instrument panel 8, the air bag cover 2 is attached in advance to the air bag case 1 in which an inflator (unillustrated), the air bag, etc., are accommodated, and the air bag device is attached to the instrument panel 8 after the air bag cover 2 and the air bag case 1 are formed into an assembly. Accordingly, the difficult operation of attaching the air bag cover 2 from the reverse side of the instrument panel is eliminated, so that the operational efficiency in assembling the air bag device to the instrument panel can be improved.

It should be noted that in the present invention the location where the air bag cover 2 is attached is not restricted to the air bag case 1, and the air bag cover 2 may be attached to the instrument panel 8 which is a base on which the air bag device body is attached. In addition, the material of the retainer 3 is not restricted to a resin, any other suitable material may be employed.

In accordance with the present invention, since the load acting at the time of the inflation of the air bag functions effectively to break the retainer, the pushing open of the air bag cover is effected smoothly.

In addition, since the retainers of the air bag cover are supported rotatably with respect to the air bag case, even when the air bag cover and the air bag case move relative to each other due to vibrations or the like occurring in the vehicle, that movement is absorbed by the rotation of the retainers. Therefore, an undue load is prevented from being applied to the retainer, and the breaking portion is hence prevented from undergoing fatigue.

Furthermore, the conventional art each retainer is tightened directly by a securing means such as a bolt, and an external force such as a torsion can occur in the breaking portion due to the tightening torque at the time of tightening. In contrast, in the present invention, because the retainers are rotatably secured to the air bag case or the base, such external forces are not applied to the retainer. Additionally, since the structure adopted is such that the retainers are rotatably held, the torque acting due to the tightening of the bolt is received not by the retainer but by the spacer. Therefore, there is still another advantage in that the vibrations of the air bag cover are not imparted to the bolt, so that the loosening of the bolt is prevented.