JP2002104124A - Air bag cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air bag cover capable of unnecessitating a relief line formed by a buried pleat of a surface skin. SOLUTION: This air bag cover 113 is constituted by providing the surface skin 114 and a cover base body 116, making a tear line portion 116b into a fragile part in the cover base body 116 and interposing a foamed layer 120 between the cover base body 116 and surface skin 114. Thickness d of the tear line portion 116b in the cover base body 116 is made smaller as compared with a general part or made zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag having a skin and a cover base, a foamed polymer material layer interposed between the skin and the cover base, and the cover base having a fragile tear line portion. About the cover.

Here, an airbag cover in an airbag device incorporated in an instrument panel will be described as an example. However, the present invention is not limited to this, and the present invention is applicable to side doors, pillars, front and back seats and the like. Of course, the present invention can be applied to an airbag cover of an airbag device to be incorporated.

[0003]

2. Description of the Related Art In an instrument panel 12 integrated with an airbag cover as shown in FIG. 1, a configuration of an airbag cover 13 at an airbag device assembling portion (line 2-2 in FIG. 1) is shown in FIG. (FIGS. 7 and 13 of JP-A-11-222089)
Etc.).

[0004] That is, a cover 14 and a cover base (cover insert) 16 are provided.
4, a foamed resin molded part (polymer foam layer) 20 is interposed. The base door portion 16a of the cover base 16 has a hinge groove 17 at a hinge portion and a tear line groove 18 at a tear line (break line) portion T on the back surface side. That is, the cover base 16 has the tear line portion T,
Weak part due to tear line groove 18 (thin part; stress concentration part)
t.

Here, the epidermis 14 is usually made of soft PVC,
It is formed by vacuum forming a soft sheet such as a polyolefin-based thermoplastic elastomer (TPO) or by slush molding using a soft PVC powder or the like. Then, a skin door portion 14a of the instrument panel skin 14
A relief line (cut line) 22 is formed around the door portion 20a (hinge portion H and tear line portion T) of the foamed resin molded portion 20a to facilitate the operation thereof.

The cover substrate 16 is usually formed of an olefin or styrene non-polar TPE.
The instrument panel base portion (hereinafter abbreviated as “instrument base portion”) 24 is usually formed of glass fiber reinforced polypropylene (GPP) in many cases, from the viewpoint of heat-fusibility. The synthetic resin injection molding section 20
Is usually formed of reaction injection foamed polyurethane, soft foamed PP, or the like.

[0007] The relief line 22 is usually
4, a foamed resin molded part 20 is provided around the skin door part 14a.
It was formed by a buried fold portion 14b that was buried (buried) in the hole.

That is, when the airbag 26 is inflated and deployed, stress concentrates on the thin portion t formed by the tear line groove 18 of the cover base 16 and the thin portion t is broken. Subsequently, in the foamed resin molded portion 20, stress is concentrated on a portion (minimum cross-sectional portion) where the distance from the bottom of the tear line groove 18 of the cover base 16 is shortest, and cracks are formed in the relief line 2.
2 runs towards the tip of the buried pleat 14b forming
Furthermore, stress concentrates also on the tip of the buried fold 14b of the skin 14, and it breaks.

[0009] The airbag device M basically includes:
An airbag 26 and an inflator 28 are provided, and a device case 30 for accommodating them and connecting them to the airbag cover 13 is provided. The airbag 26 and the inflator 28 are connected to an upper wide portion 30 of an apparatus case 30 having a rectangular shape.
a, and is stored and held in the lower narrow portion 30b.
The connection between the device case 30 and the airbag cover 13 is as follows.
The mounting is performed by engaging the mounting claws 32, 32 with front and rear mounting legs 34, 35 formed to protrude downward from the cover base 16. In the figure, reference numeral 36 denotes a diffuser plate.

[0010]

However, in the case of the airbag cover having the above structure, in order to secure the pivotal opening of the bag door portion when the bag is deployed, the relief line formed by the buried fold portion of the skin portion. Was inevitable.
The presence of the relief line has limited the design of the airbag cover, and the mold of the skin has become complicated as described in the above-mentioned publication.

In view of the above, it is an object of the present invention to provide an airbag cover which can eliminate the need for a relief line formed by buried folds in the skin.

[0012]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention have made intensive efforts to develop a narrow cross-section by reducing the distance between the tear line portion of the cover base and the facing surface of the skin. It was found that the formation of the airbag cover could secure the door opening performance when the bag was deployed without forming a relief line (cut line) by the buried folds of the skin as described above, and conceived an airbag cover having the following configuration.

[0013] In an airbag cover having a skin and a cover base, a foamed polymer material interposed between the cover base and the skin, and the cover base having a fragile portion at the tear line, the cover base has a high height at the tear line. The thickness of the molecular material foamed layer (hereinafter referred to as “foamed layer”) is made smaller or zero (0) as compared with the general part.

A bulging wall portion formed by bulging the cover base into the foam layer is formed at the tear line portion. The cross section of the bulging wall portion is substantially inverted U-shaped or substantially inverted V-shaped, and a tear line groove forming wall and a cross section are formed. A shape such as a chevron-shaped cross section in which the distance between the facing surface to the skin and the asymptote toward the tear line, a trapezoidal shape with a flat upper surface, or the like can be used.

In the above case, the top of the substantially inverted U-shape or the substantially inverted V-shape is used as a cut-and-joined portion, and the cut-and-joined portion is closed with an opening prevention film. It is good also as a structure which forms a sub-projection on both sides of the top part of.

[0016]

Next, an embodiment of the present invention will be described with reference to FIGS. Parts corresponding to the above-described example and parts corresponding to the respective embodiments are denoted by three-digit figures with the same last two digits, and the description thereof may be omitted in whole or in part.

3 and 4 show one embodiment of the present invention. FIG. 4 is a schematic end view taken along line 4-4 in FIG.

The airbag cover 113 of this embodiment is
The panel skin 114 and the cover base 11 are incorporated in the instrument panel 112 as in the above-described example.
6 and a foamed resin molded part (polymer foam layer) 120 is interposed between the cover base 116 and the skin 114. The cover base 116 has a tear line groove 118 on the back surface side, and the tear line portion T is a weak portion (stress concentration portion).

Here, the tear line groove forming wall 116b of the cover base 116 has a bulging section (bulging wall portion) in which the skin-facing surface side projects toward the skin-facing surface side, and the tear line groove forming wall 116b and the skin 114 are formed. Is shorter than the distance D between the opposing surfaces (the distance between the opposing surfaces of the cover base 116 and the skin 114) D. In particular,
The bulging cross section of the tear line groove forming wall (bulging wall portion) 116b is substantially inverted V-shaped. Here, the tear line groove forming wall 116b
Has an inverted V shape from the viewpoint of breakability (tearing), but may have an inverted U shape. From the same point of view, the wall thickness may be reduced toward the tip.

More specifically, for example, the specification of the thickness of the airbag cover 113 is as follows: the general portion overall thickness: 15 mm, the skin 114: 1 mm, the cover base 116: 4 mm, the foam layer 12
0 (distance D of the general part): 10 mm, depending on the mechanical properties (especially elongation and breaking strength) of each layer, the distance d between the opposing surfaces between the tear line groove forming wall 116b and the skin 114,
Is 0 to 5 mm, preferably 3 to 5 mm. In proportion to the distance D between the facing surface of the general portion of the skin 114 and the cover base 116 (the thickness of the general portion of the foamed resin molded portion 120) D, the distance between the facing surface of the tear line groove forming wall 116b and the skin 114 is large. The distance d is １ ／ or less, preferably １ ／ or less, more preferably １ ／ or less.

The airbag cover 113 of this embodiment is
It is manufactured by simultaneous molding with the instrument panel 112 as in the related art.

That is, beforehand, the instrument panel base 124 and the cover base 116 are made of different materials (for example, the former:
Using GPP (the latter: TPO), they are separately molded and integrated by an adhesive or heat fusion.

In addition, by two-color injection molding in which the instrument panel base and the cover base are formed by the same mold, the end faces are fused and fused together one after another without forming a polymerization portion as shown in the figure. May be. Also, a nail provided on one of them,
You may integrate by the nail | claw fitting by fitting of the fitting hole provided in the other.

Next, the TPO sheet forming the skin 114 is set on one of the foaming molds (not shown) (usually the upper mold), and the integrated instrument panel base 124 / cover base 116 is placed in the mold. Set to. And TP
After the O-sheet is vacuum shaped while being heated, the O-sheet is filled with a foamed resin material such as polyurethane formed between the integrated substrate and the skin, and after the foaming is completed, the mold is released, and the airbag of the present embodiment is released. Get the cover. At this time, it is not necessary to form a buried fold (forming a relief line) in the skin. Therefore, beautiful relief line (buried folds)
It is not necessary to form the skin by powder slush molding to form

In the present embodiment, the skin can be formed by powder slush molding. However, in the case of powder slush molding, a convex ridge for forming an embedded fold is not required, and the structure of the skin molding die is simple. And it will have durability.

In the above, it is desirable to use a sheet material or the like forming the skin 114 having relatively small breaking strength and breaking elongation in order to secure the skin breaking property (rapidity).

Next, the usage of this embodiment will be described.

As described above, the airbag device M is assembled to the instrument panel 112 having the airbag cover (part) 113 via mounting legs 134 and 135 formed on the back surface of the bag cover 113. hand,
Attach to the vehicle.

When the vehicle receives a shock equal to or greater than a predetermined value, the gas flowing from the inflator 128 through the diffuser plate 136 inflates the airbag 126, and the inflation output of the airbag 126 causes the airbag cover 1 to inflate.
The portion corresponding to the 13 tear line grooves 118 is broken. Then, since the bag door rotates about the hinge and opens the air bag outlet, the air bag 126 pops out and deploys to protect the occupant.

In the above description, the foam layer 120 and the skin 114 quickly (smoothly) follow the tear line groove 118 (the tear line portion T) even if there is no relief line (buried fold) in the skin 114 as in the prior art. Break at location.
That is, when the airbag 126 is deployed, stress concentrates on the tear line groove forming wall 116b, which is a notch, and after the tear line groove forming wall 116b breaks, in the foam layer 120, the tear line groove forming wall 116a and the skin 114 Stress concentrates on a portion where the distance between opposing surfaces is the shortest (minimum cross-sectional portion), cracks also run on the portion, and as a result, the foam layer 12
The stress is concentrated on the tear line portion T in the skin layer 114 and the skin layer 114, and both the foam layer 120 and the skin layer 114 are quickly (smoothly).
To be broken.

FIGS. 5 to 8 show end views of airbag covers according to different embodiments. The drawings of any of the embodiments are different from FIG.
7, 317, 417, and 517) in front and back, and the bag door is a double-opening (double door opening) type. However, except for FIGS. 7 and 8, it can be applied to a single opening type as shown in FIG. Things.

The embodiment shown in FIG. 5 is different from the embodiment shown in FIG.
6, the top of the tear line groove forming wall 216b formed in an inverted V-shape is used as a cut joint portion C, and the cut joint portion C is closed with an opening prevention film (paint, sheet, film) 238. If the foam injection material does not substantially flow out of the cut-off portion C during the formation of the foam layer 220, the opening prevention film 238 is not inevitable. The opening prevention film 238 is formed of a non-elongated coating, sheet, film, or the like.

The function of the airbag cover portion of this embodiment is to reduce the breaking energy of the tear line groove forming wall (bulging wall portion) 216b due to the presence of the anti-opening film 238 which does not stretch and has low strength. Therefore, the attenuation and consumption of the airbag inflation and deployment energy can be suppressed as much as possible, and as a result, the energy that contributes to the fracture due to the concentration of stress on the skin increases. Therefore, the deployment performance of the airbag is improved.

In the embodiment shown in FIG. 6, similarly to the case of FIG. 5, the point different from FIG. 4 is that the inverted V-shaped tear line groove forming wall (bulging wall portion) 3 of the cover base 316 is formed.
A sharp ridge 340 is formed at both ends of the top of 16b. By providing the two sharp tip ridges 340, the ridges hit the back of the skin when the airbag is deployed,
Make a trigger for skin rupture. Thereby, the rupture of the skin is smoothly performed, and as a result, the deployability of the airbag is improved.

In the embodiment shown in FIG. 7, the bulging cross section of the tear line groove forming wall (bulging wall portion) 418 is set such that the distance between the facing surfaces of the tear line groove forming wall 418 and the skin 414 is the tear line T.
, And gradually decreases toward the tear line T. By adopting the cross-sectional shape, the development fracture at the tear line portion T of the cover base 416 smoothly propagates to the skin 414, and the skin 414 can be reliably broken.

In the embodiment shown in FIG. 8, the bulging cross section of the tear line groove forming wall (bulging wall portion) 518 has a trapezoidal shape with a flat upper surface. By adopting the cross-sectional shape, the development fracture at the tear line portion T of the cover base body 516 smoothly propagates to the skin 514 and the skin 51 in the same manner as described above.
4 can be reliably broken.

In each of the above embodiments, the foamed polymer material layer is a foamed resin molded part. However, a foamed sheet material or the like is subjected to vacuum molding, sandwich molding, and further, a separate substrate and a skin. It may be formed integrally with a foam sheet sandwiched therebetween. In addition, the foaming material is not limited to urethane, and can be appropriately selected from foamed polyethylene, polypropylene, foamed polyvinyl chloride, and the like.

Similarly, a tear line groove forming wall 116 is formed.
The top portion (the tear line portion T) of b was made a weak portion (thinning weak portion) by thinning, but the entire tear line groove forming wall was made the same thickness, and the tear line portion was formed with a fusion line (weld line) or a perforated line. It may be formed to form a fragile portion.

In the same manner, the foamed layer usually has a cushioning effect. Therefore, in the tear line portion, all of the foam layer is left in the illustrated example. However, if the appearance and the feel of the skin are not affected, the tear line groove is formed. It is also possible to adopt a configuration in which the top of the forming wall is in contact with the skin.

As a matter of course, in each of the above embodiments, the tear line portion of the epidermis and its vicinity are flat. This is because a shape design for breaking a relief line or the like is not required on the skin side as in the related art.

[0041]

As described above, in the airbag cover of the present invention, the skin and the cover base have the tear line groove forming wall as the fragile portion, and the polymer foam layer is interposed between the cover base and the skin. In the airbag cover, the following effects are obtained by making the thickness of the foam layer in the tear line groove forming wall smaller than that of the general portion or zero (0).

The relief line formed by the buried folds of the skin can be eliminated. Therefore, the design of the airbag cover is not restricted, and the mold used for powder slush of the skin or vacuum forming can have a simple structure and durability.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an instrument panel which is an example of a vehicle interior component having a conventional airbag cover.

FIG. 2 is a schematic end view taken along line 2-2 of FIG. 1;

FIG. 3 is a schematic perspective view of an instrument panel which is an example of an automobile interior provided with the airbag cover of the present invention.

FIG. 4 is a schematic end view of the airbag cover portion (in a state where the airbag device is connected) of one embodiment of the present invention, taken along the line 4-4 in FIG. 3;

FIG. 5 is a schematic end view of a main part of an airbag cover according to another embodiment of the present invention (in a state where an airbag device is not connected).

FIG. 6 is a schematic end view of a main part of an airbag cover according to still another embodiment (in a state where an airbag device is not connected).

FIG. 7 is a schematic end view of a main part of an airbag cover according to still another embodiment (in a state where an airbag device is not connected).

FIG. 8 is a schematic end view of a main part of an airbag cover according to still another embodiment (in a state where an airbag device is not connected).

[Explanation of symbols]

12, 112 Instrument panel 13, 113, 213, 313, 413, 513 Airbag cover 14, 114, 214, 314, 414, 514 (Instrument panel) skin 16, 116, 216, 316, 416, 516 Cover base 16b, 116b, 216b, 316b, 416b, 5
16b Tear line groove forming wall (bulging wall portion) 18, 118, 218, 318, 418, 518 Tear line groove 20, 120, 220, 320, 420, 520 Foamed resin molded part 26, 126 Airbag 28, 128 Inflator d Tear line Distance between opposing surfaces between the groove forming wall and the skin D Distance between opposing surfaces of the general portion between the base door portion and the skin M Airbag device T Tea line portion H Hinge portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akio Nakano 1 Ogataai Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. F-term (reference) in Toyoda Gosei Co., Ltd. 3D044 BA07 BC03 3D054 AA03 AA06 AA14 AA17 AA18 AA22 BB09 BB10 BB16 BB21 BB23 BB24 DD13 EE19 EE20 FF17

Claims (7)

[Claims] 1. An airbag cover comprising a skin and a cover base, wherein a polymer foam layer is interposed between the skin and the cover base, and wherein the cover base has a tear line portion as a fragile portion. An airbag cover, wherein the thickness of a polymer foam layer (hereinafter, referred to as a "foam layer") at the tear line portion is made smaller or zero (0) as compared with a general portion. 2. The airbag cover according to claim 1, wherein a bulging wall portion formed by bulging the cover substrate into a foam layer is formed at a tear line portion in the cover substrate. 3. A cross section of the bulging wall formed at a tear line portion of the cover base is substantially inverted U-shaped or substantially inverted V-shaped, and a top of the substantially inverted U-shaped or substantially inverted V-shaped is cut and joined. The airbag cover according to claim 2, wherein the cut-and-joined portion is closed by an opening prevention film. 4. A cross section of the bulging wall portion formed at a tear line portion of the cover base is substantially inverted U-shaped or substantially inverted V-shaped, and is provided on both sides of a top of the substantially inverted U-shaped or substantially inverted V-shaped. The airbag cover according to claim 2, wherein a sub-projection is formed. 5. A cross section of the bulging wall portion formed at a tear line portion of the cover base is a mountain-shaped cross section in which a distance between opposing surfaces to the skin is gradually approached toward the tear line portion. Item 3. The airbag cover according to Item 2. 6. The airbag cover according to claim 2, wherein a cross section of the bulging wall portion formed at a tear line portion of the cover base has a trapezoidal shape with a flat upper surface. 7. The method according to claim 1, wherein the surface of the tear line portion and the vicinity thereof are flat.
7. The airbag cover according to 5 or 6.