JPH02303949A - Cover unit for air bag - Google Patents

Abstract

PURPOSE:To spread an air bag ideally in an objective direction by arranging a protruding part in an edge part of a break groove part corresponding to the initial break part in a small thickness part in a cover unit and first breaking the small thickness part corresponding to this protruding part. CONSTITUTION:When collision of an automobile is generated, gas is generated from a gas generator 14 in an air bag device 7, and an air bag 10 is rapidly unfolded by an inflow of this gas into the inside of the air bag 10 from a blow port 16. While following unfolded the air bag 10, a small thickness part 25 of a cover unit 21 is broken. Here in the central part first broken of the small thickness part 25, that is, in the initially broken part 28, a protruding part 29, which protrudes to a reverse side of the cover unit 21 from both side edge parts of a break groove part 24, is integrally formed. When the air bag 10 is spread, tensile breaking force in parallel to an upper surface of the cover unit 21 is concentrically applied to the small thickness part 25 in a surface side corresponding to a position of the protruding part 29. In this way, the air bag 10 is spread ideally in the objective direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an airbag cover body for protecting occupants from impacts such as collisions in automobiles and the like.

(Prior Art) Airbag devices for protecting occupants from collisions and other impacts in automobiles, etc.
The one shown in the publication is known.

This airbag device covers a folded airbag with a cover body, causes gas to flow into the airbag and inflates it, and ruptures the cover body during the inflation, causing the airbag to protrude from the cover body. By inflating it, it prevents the driver from colliding with the rim of the steering wheel or the windshield in front of them, and also works to absorb the impact in the event of a collision.

The cover body is provided with a rupture groove on the back surface to form a thin part that ruptures as the airbag expands, and defines a plurality of open parts through this thin part. When the airbag is inflated, the thin wall portion is broken, so that the plurality of openings are expanded outward from the center of the cover body, causing the airbag to protrude and inflate.

By the way, when the thin part of the cover body breaks and the airbag protrudes and inflates, the breakage of the thin part starts from the center and expands outward, and each of the plurality of open parts expands outward from the center. This allows the airbag to ideally protrude and inflate toward the center of the intended protection range, that is, toward the front of the steering wheel.

Therefore, for example, as described in Japanese Utility Model Application No. 51-36846, a lever is rotatably disposed between the back surface of the cover body and the airbag, and the lever is located at the center of the thin wall part of the cover body. A protrusion is provided at the tip facing the part, and
When the airbag inflates, the lever pressed by the airbag rotates, and the protrusion at the tip of this lever cuts through the center of the thin part of the cover body, causing the cover body to break and the airbag to open as described above. There is a structure that attempts to ideally perform protrusion expansion.

(Problem to be Solved by the Invention) However, as described above, in a structure using a lever with a protrusion, the lever with a protrusion will fly out together with the airbag when the airbag protrudes and inflates, resulting in a high risk of damage. The number is large and the cost is high.

Therefore, in order to inflate the airbag ideally in the direction of the center of the intended protection area, for example in front of the steering wheel, it is possible to prevent the cover body from breaking while ensuring safety and at low cost. It was difficult to control.

The present invention aims to solve these problems by making it possible to control the rupture of the cover body while ensuring safety and reducing costs. It is an object of the present invention to provide an airbag cover body that can ideally protrude and inflate toward the airbag.

[Structure of the invention]

(Means for Solving the Problems) The present invention covers an airbag 10 that is normally arranged in a folded state and expands due to the inflow of gas, and a thin wall portion 25 that is torn as the airbag 10 expands. In the cover body 21 of the airbag 10 made of an elastic material, which is formed by the fracture groove 24 on the back surface, a hole is formed on at least one edge of the fracture groove 24 corresponding to the initial fracture portion 28 of the thinned portion 25 toward the airbag 10. A protrusion 29 is formed to protrude.

(Function) In the present invention, when the airbag 10 is inflated, the protrusion 29 protruding from the back surface of the cover body 21 is pressed and displaced by the airbag 10 that has started to inflate.
The breaking force acts intensively on the thin wall portion 25 on the surface side of the cover body 21 corresponding to the position, and the initial breaking portion 28 of the thin wall portion 25
is first ruptured, and the airbag 1G ideally protrudes and inflates in the desired direction.

(Example) Hereinafter, the configuration of an example of the present invention will be described with reference to the drawings.

FIG. 2 shows a steering wheel for an automobile, in which a boss portion 3 is provided at the center of an annular rim portion 1 with a plurality of spoke portions 2 interposed therebetween.

As shown in FIG. 1, this boss portion 3 has a metal cylindrical boss 4 that is fitted and fixed to a steering shaft (not shown), and a boss plate 5 is mounted on the top of this boss 4. Fixed by welding.

An airbag device 7 is disposed above the boss portion 3. In this air bag device 7, a base plate 8 as a fixing member is attached to the boss plate 5 via an attachment means (not shown). The periphery of the opening 11 is fixed by an annular fixing plate 12 and a plurality of fixing devices 13 such as rivets and screws, and the airbag 10 is normally arranged in a folded state.

In addition, a gas generator 1 is installed in the opening 9 of the base plate 8.
4 is disposed, and this gas generator 14 is fixed to the base plate 8 by a fixture 13 at a flange portion 15 on the outer periphery. Note that a plurality of air outlets 16 from which gas is blown out are provided on the upper surface that fits inside the air bag 10.

A cover body 21 is fixed to the edge of the base plate 8 so as to cover the air bag 10. This cover body 21
As shown in FIGS. 3 and 4, a cylindrical base 22 fixed to the base plate 8 and a planar upper surface 23 connected to the upper part of the base 22 are integrated by an elastic body. is formed. A fracture groove 24 having a roughly V-shaped cross section is formed on the back surface of the upper surface portion 23, and a thin wall portion 25 is formed in the fracture groove 24. As shown in FIG. 2, a break line 261 at the center that breaks as the airbag 10 expands, and break lines 26 continuing on both sides of the break line 261.
b is formed into a substantially H-shape, and a pair of open portions 27 are formed.

In the center portion of the thin wall portion 25 of the cover body 21 to be broken first, that is, in the initial breaking portion 28, a breaking groove portion 24 is provided.
Projecting portions 2 projecting from both side edges to the back surface of the cover body 21
9 are integrally formed. As shown in FIG.
4, the opening end side of the rupture groove 24 is protruded from opposite sides so as to become narrower, and as shown in FIG.
When the airbag 1G hits and is pressed against the protrusions 29, the rupture grooves 2
4 is rotated inwardly, and the reaction force acts to push open the surface side of the rupture groove 24, and the thin portion 25 on the surface side corresponding to the position of the protrusion 29 is rotated parallel to the top surface of the cover body 21. The tensile breaking force acts in a concentrated manner.

Furthermore, a reinforcing body 31 is integrally buried inside the cover body 21 by insert molding to prevent the pair of open portions 27 from being broken into small pieces and scattered when the cover body 2I is broken.

Then, the airbag device 7 is activated when gas is suddenly generated from the gas generator 14 due to the impact of a car collision, etc.
This gas flows into the airbag 1G from the outlet 16, thereby rapidly deploying the airbag 10.
During the deployment of the airbag 1G, the thin wall portion 25 of the cover body 21 is broken due to its inflation pressure. At this time, the cover body 21 has a center break line 26 on its upper surface 23.
When the airbag 10 is broken from the break line 26b on both sides, the pair of openings 27 pivot upward like a hinge, and the airbag 10 deploys toward the driver, causing the driver to touch the rim 1 of the steering wheel and the front of the steering wheel. It prevents the vehicle from colliding with the glass and absorbs the impact in the event of a collision.

By the way, when the cover body 21 is attached, as shown in FIG. 6, the airbag 10 hits the protrusion 29 and presses the protrusion 29 due to the elasticity of the airbag IO in the folded state, so that the protrusions 29 are relative to each other. and is rotated inward of the breaking groove 24 so as to approach it, and the reaction force
4, and a tensile breaking force parallel to the upper surface of the cover body 2I acts intensively on the thin wall portion 25 on the front side corresponding to the position of the protruding portion 29.

When the airbag 10 is inflated, as shown in FIG.
are further rotated inward of the rupture groove 24 so that they approach each other, and the strong reaction force acts to push open the surface side of the rupture groove 24, causing the surface side corresponding to the position of the protrusion 29 to open. A strong tensile breaking force parallel to the upper surface of the cover body 21 acts intensively on the thin portion 25, and the thin portion 25 is broken from that position.

Therefore, a rupture occurs first in the center of the thin part 25 of the cover body 21, and then the rupture expands outward, and the pair of open parts 27 are properly expanded from the center to the outside, and the airbag 1
Ideally, it can be inflated to protrude toward the center of the protected area, that is, the front of the steering wheel.

Note that when the airbag 1G is inflated, a large stress is applied to the protrusion 29 of the cover body 21, but since the protrusion 29 is formed thick, it is possible to prevent the protrusion 29 from chipping and flying off. Safety can be ensured.

Further, the protrusion 29 may be provided on at least one of the edges of the rupture groove 24, but the shape may be any shape as long as the thin part 25 can be ruptured by the expansion of the airbag 1G. You may.

Further, in the above embodiment, the initial breaking part 28 is set at the center of the breaking groove part 24 of the cover body 21, but the initial breaking part controls the protruding and inflating direction of the air bag 10 depending on the application location of the air bag device. 28 as appropriate.

〔Effect of the invention〕

According to the present invention, by providing a protrusion on the edge of the breaking groove corresponding to the initial fracture portion of the thin wall portion of the cover body, the thin wall portion on the front surface side of the cover body corresponding to the position of this projection portion is first opened. Since it can be ruptured, it is possible to control the rupture of the cover body, that is, the direction in which the airbag protrudes and expands.
``The airbag can be inflated ideally in the desired direction, and it has a simple configuration that reduces costs and ensures safety.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a steering wheel showing an embodiment of the cover body of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a perspective view of the cover body as seen from the back side, and Fig. 4 is a cross section thereof. figure,
5 to 7 are cross-sectional views of a portion of the cover body. 10. Air bag, 21. Cover body, 24. Fracture groove, 25. Thin wall portion, 28. Initial fracture portion, 29.
protrusion. May 17, 1989 Inventor: Yoshitaka Ishiguro Patent applicant: Nippon Plast Co., Ltd. Yumata

Claims (1)

[Claims] (1) An airbag made of an elastic material that covers an airbag that is normally placed in a folded state and inflates when gas flows in, and that has a thin wall section formed by a rupture groove on the back surface that ruptures as the airbag expands. A cover body for an air bag, characterized in that a protrusion protruding toward the air bag is formed on at least one edge of the fracture groove corresponding to the initial fracture part of the thin part.