JP2004352179A - Automobile interior parts for air bag device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide automobile interior parts for an air bag device with a novel developing structure of an air bag cover part. <P>SOLUTION: This automobile interior part for an air bag device is equipped with a cover part 14 for run-out of an air bag. The cover part 14 comprises a base layer (inner layer) 18 and a cushion layer (outer layer) 16 contacting at the time of expansion of the air bag. The inner layer 18 has tear line grooves 28 with a breakage starting part 28a on a contact side of the air bag. Projection bars 32 are provided on the contact face side to the outer layer 16 at a position offset from the tear line groove 28, and a stress concentration point is formed by the projection bars 32. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an automobile interior part for an airbag device having a lid portion for popping out an airbag.
[0002]
Hereinafter, as an automobile interior part for an airbag device, an instrument panel (hereinafter, referred to as an “instrument panel”) to which an airbag device is mainly attached will be described as an example. In addition, a side door and a pillar to which the airbag device is attached are described. The present invention is also applicable to automobile interior parts such as front and back seats.
[0003]
[Background Art]
2. Description of the Related Art As an instrument panel (automobile interior article) to which an airbag device is mounted, there is a instrument panel body having a multi-layer structure including an inner layer and an outer layer.
[0004]
In the instrument panel body having a multi-layer structure, the inner layer and further the outer layer are morphologically devised from the viewpoint of securing the deployment performance of the airbag. I have.
[0005]
Patent Literature 1 describes an instrument panel in which a fragile portion (thin portion) is provided in a skin (outer layer) corresponding to a fragile portion (a tear line groove) formed from the back surface side of a base material (inner layer). .
[0006]
Japanese Patent Application Laid-Open No. H11-163873 discloses a protruding portion protruding from three edges of a lid (lid) excluding a hinge portion so as to bite into a pad, and a protruding cutter portion that ruptures a pad and a skin facing the lid when the lid is opened. Is described.
[0007]
[Patent Document 1]
JP-A-11-78756 [Patent Document 2]
Published Japanese Utility Model Application No. 5-3056
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an automobile interior part for an airbag device having a novel deployment structure (breakage structure) of an airbag lid.
An automotive interior product for an airbag device according to the present invention is an automotive interior product for an airbag device having a lid portion for popping out an airbag, wherein at least the lid portion abuts when the airbag inflates. An inner layer, comprising an outer layer in contact with the outer side of the inner layer, wherein the inner layer has a continuous or discontinuous tear line groove provided with a fracture starting point having an acute cross section at the contact side of the airbag,
The inner layer includes a continuous or discontinuous tear line groove having a fracture starting point on the contact side of the airbag, and a ridge or a continuous or continuous or continuous or discontinuous tear line on the contact surface side of the outer layer at a position offset from the tear line groove. With discontinuous grooves,
A stress concentration point portion is formed by the ridge or the ridge, and the stress concentration point portion is formed such that a linear distance between the stress concentration point portion and the fracture starting point portion is smaller than the thickness of the inner layer.
[0009]
In addition, it can be said that the automobile interior component for an airbag device according to the present invention has the following configuration.
[0010]
An automobile interior part for an airbag device having a lid body for popping out an airbag,
At least the lid portion includes an inner layer that contacts when the airbag inflates, and an outer layer that contacts the outside of the inner layer,
The inner layer is provided with a continuous or discontinuous tear line groove having an acute-angled cross section on the contact side of the airbag, and a ridge or a continuous or continuous or continuous or discontinuous tear line on the contact surface side with the outer layer at a position offset from the tear line groove. With discontinuous grooves,
The side edge of the ridge or the ridge is formed in a square shape, and the linear distance between the side edge of the ridge or the ridge and the tip of the tear line groove is formed to be smaller than the thickness of the inner layer. Features.
[0011]
On the contact surface side of the inner layer with the outer layer, a ridge or a continuous or discontinuous dent is provided on the contact surface side with the outer layer at a position offset from the tear line groove. The straight line distance between the stress concentration point (or square side edge) and the fracture starting point (tip) of the tear line groove is smaller than the thickness of the inner layer, so the crack generated at the fracture starting point ensures the shortest distance (Running), and the time required for completing the rupture of the inner layer is shortened. Usually, the outer layer has much lower breaking strength than the inner layer. Therefore, the deployment performance of the lid is improved. In addition, if the ridge or the ridge having the stress concentration point portion (corner side edge) is not offset from the tear line groove, that is, if it is coplanar on a plane, the tear line groove starts at a break point (sharp tip). Are substantially the same, and rupture is likely to occur on both sides, and the propagation of rupture may be suppressed. On the other hand, when offset, the stress concentration point portion of the ridge is determined on one side edge, and there is no possibility that the propagation of fracture is suppressed.
[0012]
In the above configuration, it is preferable that the cross section of the tear line groove is substantially triangular, and the stress concentration point is located on an extension of one oblique side of the triangle. As a result, the stress concentration point exists on the line of action of the rupture force, and it can be expected that the rupture propagation becomes smoother. Therefore, further improvement in the deployment performance of the lid can be expected.
[0013]
In each of the above-described configurations, when the inner layer and the outer layer are formed of the same molding material, fusion between the inner layer and the outer layer during injection molding is improved.
[0014]
In each of the above-described configurations, when the outer layer is formed by reaction injection molding with RIM urethane or the like, an increase in productivity due to a short molding cycle of the reaction injection molding can be expected.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
As an automobile interior component provided with a lid portion for popping out an airbag, an airbag lid at an assembly portion of the airbag device M (a 2-2 line portion in FIG. 1) in the instrument panel 12 as shown in FIG. The case where the configuration of the unit 14 is applied to the configuration shown in FIG. 2 will be described as an example.
[0017]
That is, a cushion layer (outer layer) 16 and a base layer (inner layer) 18 are provided. The base layer 18 has a configuration in which a base lid portion (usually made of a soft resin) 22 and a base body portion (usually made of a hard resin) 23 are fused and integrated by injection molding.
[0018]
The base lid portion 22 has left and right hinge grooves 24, 26 and a tear line groove 28 on the back surface side, and is divided by the tear line groove 28 and the hinge grooves 24, 26. , 26 can be pivoted upward about the hinge.
[0019]
Normally, the airbag body 30 is opened and expanded toward the passenger in the vehicle cabin by activating the airbag device M and breaking the tear line portion T in the airbag lid formed on the interior of the automobile. Has become.
[0020]
In the instrument panel 12, a triangular tear line groove 28 is formed in the base layer (inner layer) 18 in the illustrated example. Here, the formation form of the tear line groove 28 may be continuous or discontinuous such as perforations (stitches). Also, the cross-sectional shape of the tear line groove 28 is usually a triangular shape with an acute tip as shown in the figure, but if a reliable fracture starting point exists, a semicircle, a rectangle, a trapezoid, an inverted U-shape, Notches (slits) having substantially no gap may be used. In addition, the angle of the vertex of the cross-section triangle in the tear line groove 28 is usually 30 to 90 °.
[0021]
Then, at a position offset (displaced) from the tear line groove 28 formed in the base layer (inner layer) 18, a ridge 32 is formed on the contact surface side of the base layer (inner layer) 18 with the cushion layer (outer layer) 16. (32A) is formed (see FIGS. 3 and 4). The ridges 32 (32A) have square edges on both sides to form stress concentration points 32a.
[0022]
In the illustrated example, the form of offset of the ridge 32 is such that the acute-angled tip (break start point) 28 a of the tear line groove 28 is located outside both side edges (stress concentration point) of the ridge 32. Alternatively, a configuration may be adopted in which both sides (stress concentration points) of the ridges 32 are located inside.
In the illustrated example, one side edge (stress concentration point portion) 32a of the ridge 32 comes on an extension line L of one oblique side of a triangle which is a cross section of the tear line groove 28.
[0023]
In the case of this configuration, since the stress concentration point portion 32a is located on the line of action of the breaking force, the crack propagation of the base material layer (inner layer) 18 becomes smoother.
[0024]
In the illustrated example, since the protruding ridge 32 has an acute-angled shape, the tip of the protruding ridge 32 cuts through the cushion layer 16, so that the cushion layer 16 is more rapidly broken. However, since the tip of the ridge 32 has an acute angle (edge shape), if the remaining amount of the tip of the ridge is small, a sense of incongruity is likely to occur when touching from the surface side. In other words, the presence of the ridges 32 tends to appear on the surface side in a tactile sense.
[0025]
As shown in FIG. 4, even if one side edge (stress concentration point) 32 a of the ridge 32 </ b> A does not lie on the extension line L of one oblique side of the cross section triangle of the tear line groove 28, the top of the tear line groove 28 ( The distance from the fracture starting point portion 28a to one side edge (the left side in the example in the drawing: stress concentration point portion) 32a of the protruding ridge 32 may be shorter than the thickness of the base layer (inner layer) 18. Also, the cross-sectional shape of the protruding ridge 32A does not necessarily have to be triangular as described above, but may be arbitrary, such as a semicircular shape, a rectangular shape, a trapezoidal shape, or an inverted U-shape as shown in the figure. In the case of a semicircular shape, there is no fear that poor tactile sensation as in the case of the acute angle is generated.
[0026]
The ridges 32 (32A) may be continuous or discontinuous, as in the case of the tear line grooves 28.
In the above description, the depth of the tear line groove 28 varies depending on the material, thickness and groove form of the base layer 18, but the material is olefin-based thermoplastic elastomer (TPO), the base layer thickness is 1 to 5 mm, and the remaining thickness is t ₁ : 0.1 to 2 mm for continuous grooves and 0 to 2 mm for discontinuous grooves such as perforations (stitches). In the continuous groove, if the remaining thickness is 0, it is difficult to secure the strength of the tear line portion.
[0027]
In addition, the height of the ridges 32 is not particularly limited, and may be a size capable of forming the stress concentration point portion 32a, for example, 1 mm or more. The remaining thickness does not appear tactilely on the surface (design surface) side. Specifically, the remaining thickness t2 is set to 0.1 to ₂ mm. At this time, the smaller the remaining thickness is, the more the crack propagates to the interface between the ridges 32 and 32A of the base layer 18 and the cushion layer when the cushion layer 16 serving as the outer layer is broken. , The crack propagation is stabilized, and as a result, the cushion layer 16 is smoothly broken. From this viewpoint, the remaining thickness is desirably 0.1 to 0.5 mm.
[0028]
In FIG. 5, one side edge of the concave streak 34 formed on the contact surface side of the base layer (inner layer) 18 and the cushion layer (outer layer) 16 at a position offset from the tear line groove at the stress concentration point portion 34 a is squared. An example is shown below.
[0029]
At this time, the depth of the concave stripe 34 may be deeper or shallower than the depth of the tear line groove 28. Similarly to the above, the depth is not particularly limited as long as the stress concentration point portion 34a can be formed, and it is sufficient that the depth is 1 mm or more, and the cross-sectional shape is not limited to the triangular shape in the illustrated example. Any shape such as a semicircle, trapezoid, rectangle, U-shape, etc. The remaining thickness is set to 0.1 to 2 mm as in the case where the ridge is formed to form the stress concentration point portion.
[0030]
The ridges 34 may be continuous or discontinuous (intermittent) as in the case of the ridges 32.
[0031]
When both the ridges 32 and 32A (concave stripes 34) and the tear line groove 34 are discontinuous such as perforations, the straight-line distance between the stress concentration point and the fracture starting point is smaller than the thickness of the inner layer. If such a result is obtained, the ridges 32 and 32A (concave ridges 34) and the tear line grooves 28 do not necessarily need to completely match (correspond to), but may be shifted or alternately formed. Is also good.
[0032]
In each of the above embodiments, the inner layer is a soft resin, and the outer layer is a cushion layer (skin-integrated foam layer), but the combination is a soft resin / soft resin, a hard resin / soft resin, or a hard resin / hard. Any of resins may be used.
[0033]
Hard resins include PPT (talc-filled polypropylene), PPC (carbon-filled polypropylene), PC (polycarbonate) / ABS (acrylonitrile-butadiene-styrene terpolymer), PC (polycarbonate), ASG (allyl filled with glass fiber) , ABS (acrylonitrile-butadiene-styrene terpolymer), PPE (polyphenylene ether) and the like. Among these hard resins, a crystalline polyolefin-based resin (for example, PPT) reinforced with an inorganic filler is preferable from the viewpoint of weight reduction and the like.
[0034]
As the soft resin, from the viewpoint of PVC and weight reduction, in addition to the foamed polyurethane cushion layer, non-polar thermoplastics such as olefin (TPO), 1,2-PB (RB), and styrene (TPS) are used. Elastomers can be suitably used, but polar thermoplastic elastomers such as polyester (TPEE), amide (TPA) and urethane (TPU) can also be used.
[0035]
In the above, when the base layer (inner layer) 18 and the cushion layer (outer layer) 16 are fused, it is desirable to use a combination of non-polar resins or polar resins. In the case of mechanical coupling or mechanical coupling, a combination of non-polar resin / polar resin may be used.
[0036]
In forming, when the remaining thickness of the tear line groove, the ridge or the ridge in each layer is small, a problem of material flow is likely to occur, and therefore it is preferable to use a molding material having good fluidity.
[0037]
When the stress concentration points are formed by the ridges 34 as shown in FIG. 5, there is no portion on the cushion layer side that substantially guides the propagation of cracks, such as the ridge interface, so that brittleness is likely to occur. It is desirable to use a material having a high density.
[0038]
Next, the instrument panel having the above configuration is manufactured in the same manner as the general-purpose instrument panel having a multilayer structure.
[0039]
For example, in the case shown in FIG. 2, the base lid part 22 and the base body part 23 are formed in two colors, and then the cushion layer 16 is formed of urethane foam RIM using the base layer 18 as an insert.
[0040]
In addition, it is optional such as skin in-mold molding, integrating a separate object with an adhesive or a mechanical connection.
[0041]
The instrument panel thus manufactured is assembled with the airbag device M and mounted on an actual vehicle for use in the same manner as in the prior art.
[0042]
The airbag device M basically includes a bag body 30, an inflator 36 for allowing inflation gas to flow into the bag body 30, and a bag case 38 for integrating those members. The bag case 38 holds the inflator 36, and a diffuser can 40 for guiding the inflow of inflation gas into the bag body 30 is integrated with the bag body 30.
[0043]
Then, the front and rear mounting walls 20A and 20B formed on the back surface of the base layer 18 are inserted into and engaged with the front and rear walls 38a and 38b of the bag case 38 to form an airbag assembly, via a bracket (not shown). Attach to the body (real vehicle).
[0044]
When an impact load equal to or more than a predetermined value acts on the vehicle body, the tear line portion T of the bag lid portion 14 breaks as described below, the lid portion is opened, and the airbag 30 is rapidly inflated and deployed.
[0045]
First, the bag body 30 expands and presses the base body 20 from the back side (lower surface). As a result, stress concentrates on the bottom (top) of the tear line groove 28 in the base 20, and the top 28 a of the tear line groove 28 becomes a fracture starting point, and is formed on the contact surface side with the outer layer 16 by the ridges 32 and 32 A. The crack propagates to the stress concentration point portion 32a. Then, the crack propagates along the interface between the ridge 32 (or 32A) and the cushion layer 16 to the top 32b or near the top, and the top 32b serves as a fracture starting point of the cushion layer. The part breaks upward.
[0046]
On the other hand, when the stress concentration point portion 34a is formed by the ridge 34, the stress concentration point portion 34a becomes a fracture starting point of the cushion layer 16, a crack propagates substantially upward, and the fracture of the cushion layer 16 is completed.
[0047]
In the above description, the case where the lid portion 14 is double-opened has been described as an example.
[Brief description of the drawings]
FIG. 1 is an overall perspective view showing an instrument panel with a lid to which the present invention is applied. FIG. 2 is a schematic cross-sectional view taken along line 2-2 in FIG. 1. FIG. FIG. 4 is a sectional view of an essential part showing an example in which a stress concentration point is formed by forming a ridge on the surface side. FIG. 4 is a sectional view of an essential part showing another example. FIG. Sectional view of an essential part showing an example of forming a stress concentration point part by forming a concave stripe on the contact surface side of
12 Instrument panel (instrument panel)
14 Airbag lid 16 Instrument panel skin (outer layer)
18 cushion layer (inner layer)
28 Tear line groove 28a Sharp end (break start point)
32, 32A ridge 32a stress concentration point (one side edge of ridge)
34 Concave ridge 34a Stress concentration point (one side edge of convex ridge)

Claims (5)

An automobile interior part for an airbag device having a lid body for popping out an airbag,
At least the lid portion includes an inner layer that contacts when the airbag inflates, and an outer layer that contacts the outside of the inner layer,
The inner layer includes a continuous or discontinuous tear line groove having a fracture starting point on the contact side of the airbag, and a ridge or a ridge on a contact surface side of the outer layer at a position offset from the tear line groove. Equipped with continuous or discontinuous concave streaks,
A stress concentration point portion is formed by the ridge or the recess, and a linear distance between the stress concentration point portion and the fracture starting point portion is formed so as to be smaller than a thickness of the inner layer. Automotive interior parts for airbag devices. An automobile interior part for an airbag device having a lid body for popping out an airbag,
At least the lid portion includes an inner layer that contacts when the airbag inflates, and an outer layer that contacts the outside of the inner layer,
The inner layer includes a continuous or discontinuous tear line groove having an acute-angled cross section on the contact side of the airbag, and a ridge on a contact surface side with the outer layer at a position offset from the tear line groove. Or with a continuous or discontinuous concave streak,
The side edge of the ridge or the recess is formed in a square shape, and the linear distance between the side edge of the ridge or the recess and the tip of the tear line groove is formed to be smaller than the thickness of the inner layer. Automotive interior parts for an airbag device. The automotive interior part for an airbag device according to claim 1 or 2, wherein the cross section of the tear line groove is substantially triangular, and the stress concentration point portion is located on an extension of one oblique side of the triangle. The automotive interior part for an airbag device according to claim 1, wherein the inner layer and the outer layer are formed of the same molding material. The automotive interior part for an airbag device according to claim 1, 2 or 3, wherein the outer layer is formed by reaction injection molding.

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