JPH0451076Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to an airbag cover body that covers a folded airbag.

(Prior art) Japanese Patent Publication No. 53-24693 or Japanese Patent Publication No. 63-17657
The publication discloses a substantially rectangular airbag cover body that accommodates an airbag in the center of the steering wheel.

As shown in FIGS. 4 and 5, the airbag cover body 11 is formed with a thin-walled slit that is capable of breaking when the airbag expands. The broken part 12 is
As shown in FIG. 4, it is formed in a shape similar to an H-shape, and the broken portion 13 is formed in an H-shape as shown in FIG.

Then, the airbag is rapidly inflated by gas suddenly generated from the inflator activated in a vehicle collision, etc., but when the airbag inflates, it breaks through the airbag cover body 11 on the top surface and expands. .

When this airbag cover body 11 is torn, the breakage starts from the center 14 of the airbag cover body 11, and in principle, the breakage occurs along the breakage portion 12 or 13 of the thin-walled slit formed in the cover body. proceed. Otherwise, there is a risk that small pieces of the covering material will fly off and cause secondary problems. Therefore, the thickness of the thin slit was determined to be 0.6 from various experiments.
The general setting value is around mm.

(Problems to be Solved by the Invention) However, the airbag deploys at a very high speed, and there is no certainty that the airbag will break along the thin slits set in the airbag cover body 11. Theoretically, the progression of rupture is
Fragile break 12 or 1 due to thin-walled slit
However, in the case of ultra-high-speed fracture, results that cannot necessarily be predicted by this general theory may occur. The actually measured rupture speed was such that the rupture process was completed in about 5/1000 seconds, and this speed was outside the generally accepted range of high-speed impact tension.

Considering such a phenomenon as a premise, the breaking portion 12 or 13 of the thin slit used in the current airbag cover body 11 is H-shaped or a similar shape, and the breaking starts from the center 14. After progressing left and right, it progresses up and down, but when the direction of fracture changes up and down,
A direction change of 90° or close to 90° is required. It is questionable whether the progress of ultra-high-speed fracture can cope with such rapid angle changes, and there are some concerns from the viewpoint of reliability.

An object of the present invention is to eliminate the fear that the direction of fracture in the airbag cover body may not be able to follow sudden changes in shape by preventing the possibility that the direction of fracture propagation will change suddenly at a certain point.

[Structure of the idea]

(Means for Solving the Problems) The present invention provides an airbag cover body that accommodates an airbag and has a rupture portion that can be ruptured by the expansion of the airbag, in which a lateral rupture portion 21 is formed in the center. , circular arc-shaped fracture portions 22 are formed that continue in an arc from both ends of the horizontal fracture portion 21 toward the diagonally upper side and the diagonally lower side. The acute-angled tip portion 25 of the expanded portion 24 formed between the arcuate broken portions 22 is thick.

(Function) In the present invention, since there is no discontinuity in the direction change part from the transverse fracture part 21 to the arcuate fracture part 22, the direction of the fracture progression is smoothly changed in this part, and the high-speed fracture progresses. definitely guided. Also,
The risk of small pieces of the left and right acute-angled tip portions 25 being broken and scattered is prevented by making the acute-angled tip portions 25 thin.

(Example) Hereinafter, the present invention will be explained in detail with reference to the example shown in FIGS. 1 to 3.

As shown in FIG. 1, a substantially rectangular airbag cover body 11 containing an airbag is provided in the center of the steering wheel 10. As shown in FIG. This air bag cover body 11 has a thin slit formed in a breaking portion (indicated by a broken line in the figure) that can break when the air bag expands.

As this broken part, a horizontal broken part 21 is formed in the center so as to roughly divide the upper and lower parts into two, and from both ends of this horizontal broken part 21 toward the diagonally upper side and the diagonally lower side (a rectangular shape) Airbag cover body 1
1), a continuous arc-shaped broken portion 22 is formed in a circular arc.

Deployment portions 23 are provided on both upper and lower sides of the lateral fracture portion 21.
Further, a development section 24 is defined between the upper and lower arcuate break sections 22 on both left and right sides of the lateral break section 21 . An acute-angled tip portion 25 is formed between the upper and lower large-radius arc-shaped fracture portions 22 of the left and right expanded portions 24, and this acute-angled tip portion 25 is formed thick as shown in FIG. has been done. The reason for this thick wall is the acute-angled tip 25.
This is to prevent the risk of small pieces flying off.

This acute-angled tip 25 may have a simple thick-walled shape, but is preferably formed in a protruding shape toward the center inside the cover body, as shown in FIG. This portion is referred to as a protruding portion 26. In this way, when the air bag 27 is assembled into the cover body 11, the protrusion 26 only needs to be partially deformed, and it is possible to prevent the overall appearance of the cover body 11 from deforming. As shown in FIG. 3, as the fracture progresses, the air bag 27 pushes up the protrusion 26 and applies tension to the acute-angled tip 25 from below, thereby ensuring that the acute-angled tip 25 is The cover was flipped up to the top surface,
This has the effect of smoothing the progress of the breakage of the acute-angled tip portion 25 during the progress of the breakage.

Then, when the air bag 27 is inflated, there is no discontinuity in the direction change part from the lateral fracture part 21 to the arcuate fracture part 22, so the direction of the fracture progresses smoothly in this part. Therefore, the breaking portions 21 and 22 reliably guide the progress of high-speed breaking. In addition, the left and right acute-angled tips 25
The risk of the small pieces being broken and scattered can be prevented by thickly reinforcing the sharp end portion 25.

[Effect of idea]

According to the present invention, a transverse fracture part is formed in the center of the airbag cover body, and arc-shaped fractures that continue in an arc from both ends of the transverse fracture part in four directions, diagonally upward and diagonally downward. Since the fracture is formed, there is no risk that the direction of fracture propagation in the air bag cover body will change suddenly, and the fracture will proceed at high speed along a gentle continuous curve formed from the transverse fracture to the arcuate fracture. is definitely induced. In addition, since the sharp-angled tip of the expanded portion formed between the upper and lower arc-shaped broken portions on both the left and right sides of the horizontal broken portion is formed thick, small pieces of the acute-angled tip are broken and scattered. Can prevent danger.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a steering wheel showing an embodiment of the air bag cover body of the present invention, Fig. 2 is a sectional view of the air bag cover body, Fig. 3 is a sectional view of the air bag when the air bag is activated, and Fig. 4 is a sectional view of the air bag cover body. Figure and 5th
Each figure is a plan view showing a conventional airbag cover body. DESCRIPTION OF SYMBOLS 11...Air bag cover body, 21...Transverse direction fracture part, 22...Circular fracture part, 24...Development part, 25...Acute angle tip part, 27...Air bag.

Claims (1)

[Scope of utility model registration request] In an airbag cover body that houses an airbag and has a fractured part that can be fractured by the expansion of the airbag, a transverse fractured part is formed in the center, and diagonally upward and diagonally downward sides are formed from both ends of this transverse fractured part. A continuous arc-shaped fracture part is formed in four directions, and an acute-angled tip of the developed part is formed between the upper and lower arc-shaped fracture parts on both the left and right sides of the horizontal fracture part. An airbag cover body characterized by being formed with a thick wall.