JP4169672B2 - Airbag cover - Google Patents

Description

  The present invention relates to an airbag cover.

The airbag device senses an impact when the automobile receives an impact, inflates and deploys the airbag, and interposes between the vehicle body and the occupant, thereby protecting the occupant.
In recent years, it has become widespread, and in addition to the steering wheel for the driver's seat and the instrument panel for the passenger's seat, a side airbag that protects the passengers from the impact on the side is located on the upper part of the vehicle side window. It came to be arranged.
Among these, in the airbag device for the passenger seat that is arranged inside the instrument panel, an airbag cover that covers it is prepared separately from the instrument panel, and this is provided on the instrument panel. In recent years, there has been a desire to streamline manufacturing and assembly operations by integrating them into modules, and to improve the appearance of instrument panels as interior parts. Has been.

And what integrated the airbag cover body in the instrument panel in this way has already been proposed, for example, what is indicated in JP, 11-29069, A (patent documents 1) uses an instrument panel for an airbag. Injection molding is performed without providing an opening, and laser processing is performed at a location corresponding to the airbag storage position on the back of the panel to form a planned fracture line.
In addition, there has also been proposed a molding method in which a planned fracture line is formed at the time of molding without post-processing the planned fracture line for deploying the airbag cover body after panel formation (Japanese Patent Laid-Open No. 2002-2002). 234413, Patent Document 2).

However, the former method of post-processing the expected fracture line requires a laser processing machine for this purpose, and also has a problem from the viewpoint of productivity, such as requiring subtle processing operations after molding. .
In addition, the latter molding method is a rational method in that no post-processing is required, but it is necessary to provide a core for forming a planned fracture line in the molding die so that it can be moved forward and backward. It becomes complicated and the molding method becomes complicated.

In addition, since the instrument panel is an interior part, its appearance and touch are also important. Therefore, various types of two-layer structures in which the surface layer of the panel is made of a soft and soft material and laminated on the base material layer have been proposed.
However, in the case of such a two-layer structure, it is technically difficult to stably obtain a predetermined breaking property. That is, the present inventor has found out from various trial results based on the teachings of the prior art that technical means for stably causing the skin layer to rupture directly above the groove provided in the base material layer. We have the knowledge that it is necessary. This is because the airbag cover is not necessarily pushed up uniformly from the lower airbag, and it is easy to break in a direction inclined with respect to the upward direction by applying a shearing force due to a stepped uplift. Presumed. For example, in the case of a single flap type (single-opening type) cover, the relationship between the door forming portion and the periphery thereof, and in the case of a twin flap type (double-opening type) cover, there is a relationship in which the adjacent flaps are pushed up unevenly. is there. This breaking angle can be either a direction directly above or a similar direction, and the angle when tilting is not likely to be constant. Therefore, selection of a material for obtaining desired fracture characteristics, specification of molding processing conditions that can stably use physical properties of the specific material, and strict quality control are required, and there is a concern about a significant increase in cost.

In such an airbag cover having a two-layer structure, proposals have also been made to reliably break the planned break line with a smaller force. That is, in Japanese translations of PCT publication No. 2000-512953 (Patent Document 3), the cover body does not continue to break beyond the end of the intended breaking line on the cover body of the airbag having a smooth surface cover layer. Has been proposed for a two-layer airbag cover body that can be broken by a smaller force and that can change the opening force and breaking force without changing the visual and / or mechanical properties.
According to this, in the groove part of a base material layer, it is supposed that a fracture line will be formed in the edge between the part where a surface layer and a base material layer extend in each other layer.
With such a configuration, the two-layer contact surfaces are ruptured, and it is considered that the rupture as designed along the planned rupture line can be more reliably performed.
JP-A-11-291069 JP2002-234413 Special table 2000-512953

However, as described above, the airbag cover is an interior part of an automobile, and its appearance and feel are also important.
When the contact surface between the surface layer and the base material layer is a fracture line, a thin portion is also formed on the surface layer side. As a result, the surface layer is originally thin. Further, since the thin portion is provided, the visual influence is also recognized on the surface side of the portion, and the expected fracture line is visually recognized. In addition, when touched with a hand or a finger, it differs from the surrounding touch, causing problems in appearance and touch.
Furthermore, since a thin wall portion is provided on the surface layer with a soft feeling that is originally thin on the base material layer provided with the groove, it is easy to break during the operation of the airbag. There is also concern about mechanical weakness and damage.

Under such circumstances, the present invention is an airbag cover suitable for instrument panel integration in which a soft decorative surface layer is provided on a base material layer, and is along a planned fracture line when the airbag device is in operation. It is a reliable air bag cover as a safety device that can be reliably broken, and in normal times its surface appearance is no different from the appearance of the surrounding area, and it is visually tactile An object of the present invention is to provide an airbag cover that is also integrated.
In addition, the present invention provides an airbag cover suitable for instrument panel integration that can be easily molded without requiring post-molding processing and without requiring a complicated mold or molding method. It is the purpose.

  As a result of intensive studies, the inventor has determined that the structure of the planned break line is the base material layer side in an airbag cover suitable for instrument panel integration having a structure in which a soft surface layer is provided on the base material layer. It has been found that it is effective to provide a bottomed groove and form a raised portion from the surface layer side along the wall portion of the groove, and the present invention has been achieved.

That is, the present invention
(1) An airbag cover in which a breakable portion that covers the bulging direction of an airbag device incorporating a stored airbag and forms a door portion by deployment of the airbag is formed;
A base layer made of a hard resin disposed on the airbag device side, and a surface layer made of a soft resin made of a polyurethane resin laminated on the base layer;
The part to be broken is a bottomed groove provided on the side opposite to the airbag device of the base material layer, and a raised part is formed along the wall of the groove on the surface layer side corresponding to the groove, and the base material in the part to be broken Adhesive strength between the surface layer and the surface layer is sufficient to maintain the laminated state when the airbag cover is ruptured by an urethane bond between the surface layer and an adhesive having a free isocyanate group. Airbag cover, characterized by
(2) The airbag cover according to (1), wherein the raised portions are formed on both left and right sides of the groove portion,
(3) The airbag cover according to (1) or (2), which is integrated with an instrument panel,
( 4 ) The airbag cover according to ( 3 ), wherein the surface layer has a tensile strength of 70 kgf / cm or less and is smaller than an adhesive strength between the base material layer and the surface layer.
It is about.

In the present invention, the airbag device is activated by providing a raised portion along the wall portion of the groove portion from the surface layer side corresponding to the groove portion of the base material layer that forms the planned fracture line of the airbag cover. When pushing up the airbag from below, even if a shear force is generated at the planned breakage portion, the displacement of the planned breakage position can be suppressed as much as possible, and the airbag cover can be broken substantially at the planned breakage position. The airbag can be deployed. In addition, since the thin soft surface layer does not have a substantially thin portion, it can be integrated with the periphery without impairing the appearance and tactile sensation on the surface side.
Furthermore, the airbag cover of the present invention can be manufactured only by a molding process without requiring post-processing after molding, and does not require a complicated mold for molding, so that general insert molding is possible. Can be handled by type.

As described above, the airbag cover of the present invention is composed of the base material layer and the surface layer laminated thereon.
The base material layer is preferably made of a PPC resin having a thickness of 2.5 to 4.0 mm and a relatively hard material such as polypropylene reinforced with talc or the like. Moreover, it is preferable that the surface layer laminated | stacked on it is 0.5-3.0 mm in thickness, and is comprised with a soft material, for example, a polyurethane. Of course, you are not limited to these materials. In short, any material may be used as long as the base material layer is harder and can maintain the necessary strength as an airbag cover, and the surface layer is softer, preferably elastic, and improves the surface appearance and touch.

In the airbag cover of the present invention, the structure around the bottomed groove portion that forms the planned fracture line is important.
That is, by first forming a bottomed groove, it contributes to the suppression of uneven bulging when the airbag cover is broken due to the expansion of the airbag, and prevents the molding material for the surface layer from entering the groove during molding. .
Further, the groove portion is provided in the base material layer from the airbag device side so that the remaining groove thickness is preferably 0.4 to 0.8 mm, and the surface layer is a thick portion along the upper wall portion. It is important that the surface layer forms a raised portion of preferably 0.5 to 1.5 mm. The surface layer does not form a particularly thin portion around the groove.

By adopting such a structure for the planned fracture line, even when a shearing force is applied by pushing up the airbag to be inflated from below during operation of the airbag device, an oblique direction from the groove portion of the base material layer for that purpose, Alternatively, even when it breaks in the lateral direction, it can reach a thin and soft surface layer with a slight deviation, so the deviation of the planned breaking line can be suppressed to a slight deviation, and the planned breaking line is substantially reduced. The airbag cover can be deployed along
In addition to this, it occurs when the surface layer peels off while the base layer is peeled off by bonding the base material layer and the surface layer in the planned breaking portion with sufficient adhesive strength to maintain the laminated state at the time of breaking. Deviation of the planned fracture site can also be prevented.

On the other hand, since the surface layer does not have a particularly thin portion in the periphery corresponding to the groove portion, it does not impair the surface appearance of the airbag cover, and the periphery of the instrument panel in which it is integrated It is well integrated and integrated visually and tactilely, and the airbag cover is not recognized on the instrument panel.
Of course, within the scope of the object of the present invention, that is, to the extent that the surface side is not visually or tactilely affected, if necessary, the surface layer may be provided with a portion that is thinner than the surroundings. In addition, the planned breaking line can be provided in a U-shape in the case of a single door and in an H shape in the case of a double door, according to the shape of the door portion of the airbag cover.
The airbag cover of the present invention is particularly suitable for instrument panel integration, but is not limited thereto.

  The airbag cover of the present invention can be formed easily by injection molding a base material layer having a groove part that forms a predetermined breaking line, and a surface layer can be easily formed thereon by polyurethane reaction injection molding. it can.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of an instrument panel on which an integrally formed airbag cover is mounted. In FIG. 1, B is a planned fracture line provided on the back surface, and A and C form a hinge part of a door to be cleaved. FIG. 2 is a cross-sectional view taken along the arrow in FIG. 1, and includes a wall portion 21 in which an engagement hole 22 is formed to engage with a hook 9 of a reaction can 8 fixed to a steering member (not shown). An air bag cover is shown in which an inner member 20 made of TPO resin is attached to the back surface of the substrate 1 by vibration welding or the like.

The door portion 5 is pushed up by the expansion of the airbag 10 and is cleaved, and the airbag 10 is deployed in the vehicle interior through the opening formed thereby. The door support portion 23 is coupled to the wall portion 21 via a hinge 24 and is positioned so as to overlap the hinge portions A and C when the airbag 10 is deployed to support the door portion 5. The airbag cover is a so-called seamless instrument panel, and is a panel that covers almost the entire width of the upper surface of the instrument panel.
2 and 3, reference numeral 1 denotes a base material layer, 2 denotes a bottomed groove provided in the base material layer, 3 denotes a surface layer, and 4 denotes a surface layer raised portion.

The shape of the surface layer raised portion 4 may be substantially semicircular as shown in B portion of FIG. 2, or may be rectangular rib shape as shown in A portion of FIG. May be provided on one side (for example, part A) or may be provided on both sides (for example, part B). Further, the surface raised portions may be provided intermittently at appropriate intervals in addition to being provided continuously along the groove portion 2.
Next, the molding method will be described. 1 is composed of a polypropylene resin whose strength is increased by adding talc in a base material layer that has been injection molded in advance. Reference numeral 2 denotes a bottomed weak portion provided in the base material layer, and an adhesive having a free isocyanate group is applied to a portion corresponding to the weak portion (the coated surface is a bottomed weak portion in FIG. 3). 2) It is 40 mm wide around the center-corresponding portion, that is, 20 mm wide on the left and right sides, and is applied to a range slightly exceeding the ridges on both sides). 3 is a surface layer made of a non-foamed polyurethane resin, and the polyurethane uses a molding material comprising a polyol and an isocyanate having an average molecular weight of 2000 to 6000, and the isocyanate has a weight of 1: 1 of MDI, for example, polyol-modified MDI and non-modified MDI. Using a mixture in a ratio, it is laminated by reaction injection molding on the inserted base material, and strongly bonded so that no delamination occurs between the adhesive and the adhesive even when it breaks due to urethane bonding Has been. Reference numeral 4 denotes a surface layer ridge. By providing such a raised portion, the effect of increasing the bonding area can be expressed, and the strength of the adhesive force due to this can also be taken into account. The displacement can be suppressed as much as possible, and the fracture can be performed substantially in accordance with the planned fracture line. In this case, in order to obtain a further desired breaking characteristic, in the structure as shown in FIG. 3, the weak part of the base material layer can be protruded to the surface layer side, and the surface layer can be made thin.
In addition, the raised part 4 of the surface layer may be provided continuously along the weak part, or may be provided intermittently at appropriate intervals, and further provided on both sides of the weak part and only on one side. You can also.

The perspective view of the instrument panel integrated airbag cover carrying the airbag cover integrally formed of this invention. Cross-sectional explanatory drawing of the arrow location in FIG. FIG. 3 is a detailed view of the groove portion shown in FIG. 2, and is a cross-sectional explanatory view of the groove portion forming the planned break line of the airbag cover of the present invention.

Explanation of symbols

1: Base material layer 2: Groove part 3: Surface layer 4: Surface layer raised part

Claims (4)

An airbag cover formed with a planned breakage portion that covers the airbag inflating direction of an airbag device incorporating a stored airbag and forms a door portion by deployment of the airbag;
A base layer made of a hard resin disposed on the airbag device side, and a surface layer made of a soft resin made of a polyurethane resin laminated on the base layer;
The part to be broken is a bottomed groove provided on the side opposite to the airbag device of the base material layer, and the surface layer corresponding to the groove is formed with a raised part along the wall part of the groove, and the base material layer in the part to be broken Adhesive strength between the surface layer and the surface layer is sufficient to maintain the laminated state when the airbag cover is broken by urethane bonding between the surface layer and an adhesive having a free isocyanate group. A featured airbag cover.   The airbag cover according to claim 1, wherein the raised portions are formed on both left and right sides of the groove portion.   The airbag cover according to claim 1 or 2, wherein the airbag cover is integrated with the instrument panel. The airbag cover according to claim 3 , wherein the tensile strength of the surface layer is 70 kgf / cm or less, which is smaller than the adhesive strength between the base material layer and the surface layer.

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