JPH06239192A - Pad cover for air bag system - Google Patents

Abstract

PURPOSE:To provide a pad cover for air bag system for preventing the cleavage of a tear line from promotion without appreciably extending a desired region and for smoothly and completely inflating the cleaved cover part by reaching the cleavage of the tear line to the desired area regardless of a change in an ambient atmosphere. CONSTITUTION:An inflation promotion part 10 is provided at either side 3 of a pad cover 1. Each inflation promoting part has a groove 11 oriented nearly in parallel with a lateral groove 6 in an H-shaped tear line. The groove is formed in the rear of each end wall 3a for a predetermined length to constitute a fragile part discontinued to the tear line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pad cover for an air bag system, and more particularly to a pad cover having a top surface portion and a side surface portion that form an air bag accommodating area of the air bag system. The present invention relates to a pad cover for an airbag system, which is provided with a tear line which promotes the tearing of the pad cover at least on the top surface portion.

[0002]

2. Description of the Related Art An airbag system, which is disposed on a steering wheel or an instrument panel of a vehicle such as an automobile for the purpose of protecting an occupant, has been widely put into practical use.
BACKGROUND ART An airbag system generally forms an air cushion between a driver and a steering wheel or the like to inflate an airbag composed of a bag and to absorb the impact when an unexpected impact or a sudden deceleration of a vehicle occurs. . An airbag system is generally configured as an in-vehicle unit called an airbag module or an airbag unit, and is used as an inflator (gas generator) that generates relatively high-pressure gas and a device in a folded state. An airbag housed inside and a pad cover facing the vehicle compartment are provided (see, for example, Japanese Examined Patent Publication No. 61-44708, Japanese Unexamined Patent Publication No. 3-167045, and Japanese Unexamined Utility Model Publication No. 2-91051). .

The inflator includes a chemical substance that generates a gas and an igniter that ignites the chemical substance based on a signal from the impact detection sensor, and introduces the gas generated from the chemical substance into the airbag. The airbag stored in the device is formed into a bag to seal the generated gas, and when the gas is introduced, the airbag expands almost instantly, the pad cover is broken, and the steering wheel, etc. Deploy in between.

The pad cover is generally called a storage pad, a module cover or a lid, and always functions as a case or housing for accommodating the airbag, and when the airbag is deployed, it is relatively easily broken by the expansion of the airbag. And ensures a smooth inflation of the airbag. In order to ensure a reliable and quick break of the pad cover, a tearing portion that promotes relatively easy tearing of the pad cover, that is, a tear line is provided at a predetermined portion of the pad cover. The tear line is generally formed by forming a slit or groove for tearing on the back surface of the pad cover and locally thinning the pad cover. In one form of pad cover,
The tear line is placed in an H shape on the top surface.

In one conventional design of the pad cover, the cleaved cover portion spreads greatly toward the passenger compartment,
Both vertical line portions of the H-shaped tear line extend beyond the top surface portion to the side wall portion and reach the undercut portion of the pad cover or the edge of the side wall. Also, in other conventional pad covers, both vertical line parts of the H-shaped tear line end in the edge area of the top surface part, while the split cover part smoothly expands due to the inflation of the airbag. A slit or groove that forms a rotation axis or a development support axis of the cover portion is provided on the back surface of the top surface portion. Such rotation axes are arranged, for example, on both sides of the tear line substantially in parallel with the central horizontal line portion extending in the horizontal direction of the H-shaped tear line, and the upper and lower ends and the lower and lower ends of both H-shaped vertical line portions are provided. Are positioned so as to connect to each other.

[0006]

However, in the pad cover having the above-described conventional structure provided with the vertical line portion of the tear line extending to the edge, the airbag is deployed particularly in a high temperature atmosphere, for example, an extremely hot atmosphere of 90 ° C. At times, tearing of the tear line may proceed beyond the undercut portion or the edge of the side wall, damaging or destroying the attachment portion or the support portion of the pad cover. Further, in the pad cover having the above-described conventional structure in which the expanded cover portion has the pivot axis of the cover portion, the tear line is sufficiently cleaved when the airbag is deployed particularly in a low temperature atmosphere, for example, a cold atmosphere of -40 ° C. Therefore, there is a possibility that the smooth and complete expansion of the cover portion cannot be achieved.

The present invention has been made in view of the above points, and an object thereof is to cause the tear line to be cleaved to reach a desired portion regardless of the change of the surrounding atmosphere and to tear the tear line. (EN) It is possible to provide a pad cover for an airbag system, which does not proceed much beyond a desired area and can smoothly and completely expand a cleaved cover part.

[0008]

In order to achieve the above object, the present invention has a top surface portion and a side surface portion that form an airbag storage area of an airbag system, and the pad cover is torn when the airbag is deployed. In an air bag system pad cover having at least the top surface portion for promoting a tear line, a deployment promoting portion having a fragile portion discontinuous with the tear line is provided, and the fragile portion is an end portion of the tear line. Is disposed on the side surface at a position separated by a predetermined distance from, and is oriented substantially parallel to a rotation axis that constitutes a rotation center of the cover portion when the cover portion that has been cleaved is deployed. A pad cover for an airbag system is provided.

In a preferred embodiment of the present invention, the weakened portion has a U-shaped or V-shaped cross-section groove arranged in substantially the same region as the pivot axis. In another embodiment, the fragile portion is formed by so-called dam-shaped unevenness, serration, or serrated step having a predetermined pitch. In another preferred embodiment of the present invention, the deployment promoting section measures approximately 1/100 of the total height of the side surface section, as measured from the connecting section between the top surface section and the side surface section.
It is arranged at a position within the range of 4 to 2/3. More preferably, the distance between the weakened portion and the tear line is set to be about 10 mm to 55 mm along the surface of the pad cover.

As a molding material for the pad cover, a thermoplastic elastomer and a thermoplastic resin can be preferably used. Further, the pad cover is preferably integrally molded by an injection molding machine by a one-color molding method or a two-color molding method. Examples of thermoplastic elastomers include polyolefin elastomers such as polyethylene and polypropylene; polystyrene elastomers such as polystyrene, polymethylstyrene and hydrogenated polystyrene; polyurethane elastomers; vinyl chloride elastomers; polyester elastomers; polyamide elastomers. These elastomers may be used alone or in combination of two or more.

Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene and polystyrene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; nylon 6, nylon 6,6, nylon 6,10, nylon 4,6, etc. Polyamide resin other than polyphenylene oxide resin, polycarbonate resin, polyoxymethylene resin, polysulfone resin, polyethersulfone resin, ethylene-vinyl alcohol resin, ABS resin, acrylic-acrylonitrile-styrene resin, acrylic resin, methacrylic resin, ethylene -Ethyl acrylate resin, ethylene-ethyl methacrylate resin, methacryl-styrene resin, liquid crystalline polymer and the like can be mentioned. Even if these resins are used alone, 2
The above may be used in combination.

These thermoplastic resins or thermoplastic elastomers are filled, if necessary, for the purpose of improving the amount, flame retardancy, moldability, dimensional stability, appearance, weather resistance, tearability, lightness, etc. Agents, flame retardants, plasticizers, antioxidants, antistatic agents, colorants, ultraviolet absorbers, foaming agents and the like may be added. As the filler, iron oxide, alumina, magnesia,
Metal oxides such as zinc oxide; metal powders such as nickel, zinc, copper and tungsten; silicates such as talc, mica and wollastonite; sulfates such as calcium sulfide and barium sulfate; potassium titanate and barium titanate. In addition to titanates such as ferrite, graphite, carbon black, calcium carbonate, glass beads, glass bubbles, etc., flame retardants include inorganic flame retardants such as antimony oxide and zirconium oxide; organic compounds such as phosphate esters. Examples include flame retardants. Examples of antioxidants include phenolic compounds, examples of antistatic agents include various surfactants, examples of colorants include cadmium yellow, flame retardant azo dyes, red colorants, and the like, and ultraviolet absorbers. Examples include acrylonitrile-based compounds, triazole-based compounds, salicylic acid-based compounds, and the like. Examples of the foaming agent include organic compounds such as azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetramine, 4,4′-oxybisbenzenesulfonyl hydrazide and p-toluenesulfonyl hydrazide.

Further, in an embodiment of the present invention, a deployment promoting portion is provided on each of both end wall portions forming the side surface portion.
However, the arrangement of the deployment promoting portion is not limited to such an arrangement, and for example, the deployment promoting portion may be provided only on one end wall portion, or the side surface portion is a peripheral wall, for example, a circumferential wall. In this case, the expansion promoting portion may be provided over the entire circumference or a part of the peripheral wall.

[0014]

In general, the pad cover is difficult to be cleaved in a low temperature atmosphere and is likely to be cleaved in a high temperature atmosphere. However, according to the pad cover of the present invention, since the fragile portion is provided, Even if the cleavage does not reach the fragile portion, the tear line is promoted to be cleaved, while under high temperature atmosphere, the progress of the cleavage is canceled in the discontinuous region between the end of the tear line and the fragile portion, Excessive progress of cleavage is prevented. For example, according to the pad cover of the present invention, in both the cold atmosphere of -40 ° C and the extremely hot atmosphere of 90 ° C, the cleavage along the tear line progresses to the desired site, and the cleavage exceeds the desired region. Does not proceed. Further, the split cover portion smoothly and reliably spreads in both the cold atmosphere and the extremely hot atmosphere without hindering the deployment of the airbag and without damaging or damaging the mounting portion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. 1 and 2 are an overall perspective view and a partially enlarged perspective view showing a pad cover for an airbag system according to a first embodiment of the present invention. 3 is a sectional view of the pad cover taken along the line AA of FIG.

The airbag system pad cover 1 shown in FIG. 1 is integrally molded by an injection molding machine by a one-color molding method, and has a top surface portion 2 facing the passenger compartment and a side surface portion extending downward from the top surface portion 2. 3 and 3. The top surface portion 2 has an end wall portion 3a and a side wall portion 3 of the side surface portion 3 at edges or boundaries 7 and 8.
b, respectively, and the top surface portion 2, the end wall portion 3a, and the side wall portion 3b are connected to the airbag system (not shown) so as to form a storage area of the airbag system. It is generally curved or bent inward.

A continuous groove having a V-shaped or U-shaped cross section, that is, a tear line 4 (shown by a broken line) is formed on the back surface of the top surface portion 2 to promote the tearing of the pad cover 1 when the airbag is deployed. The tear line 4 has an H shape as a whole and is arranged on the back surface of the top surface portion 2, and locally thins the top surface portion 2 to induce the tearing of the top surface portion 2 when the airbag is deployed. The tear line 4 extends in a direction substantially orthogonal to the vertical grooves 5 and 5 and the vertical grooves 5 and 5 which form each H-shaped vertical line portion, and
And a lateral groove 6 forming a central lateral line portion of the shape. As shown in FIG. 2, each vertical groove 5 ends immediately before reaching the edge 7, and the end of the vertical groove 5 and the edge 7 are separated by a distance L.
Are separated from each other. In this example, the end of the vertical groove 5 and
The distance L to the edge 7 is set to about 10 mm.

Each end wall portion 3a is provided with a deployment promoting portion 10 extending substantially parallel to the lateral groove 6. In the development promotion unit 10,
As shown in FIG. 3, a fragile portion oriented substantially parallel to the lateral groove 6, that is, a groove 11 having a U-shaped cross-section is provided.
Is formed on the back surface of the end wall portion 3a over a predetermined length. The total length of the groove 11 is about 20 mm than the distance between the vertical grooves 5 and 5.
It is long and protrudes about 10 mm to the left and right with respect to the vertical grooves 5, 5. Further, the distance h from the edge portion 7 to the groove 11 is preferably set within a range of about 1/4 to 2/3 of the total height H of the end wall portion 3a, measured from the edge portion 7, The distance S between 11 and the end of the longitudinal groove 5 is preferably set along the surface of the pad cover 1 to be about 10 mm to 55 mm.
The expansion promoting portion 10 may have any structure as long as it can give a locally weakened structure to the side surface portion 3 (end wall portion 3a), and is not limited to the groove 11 having a U-shaped cross section. Therefore, various structures can be adopted as the structure of the expansion promoting portion 10, for example, a groove having a V-shaped cross section, or a so-called dam-like unevenness having a predetermined pitch, serrations, or sawtooth step portions. The expansion promoting portion 10 may be formed by.

FIG. 4 is a partially enlarged perspective view of the pad cover according to the second embodiment of the present invention. The pad cover 1 shown in FIG. 4 has substantially the same general structure as the pad cover of the first embodiment. In FIG. 4, the same members or parts as those of the first embodiment are the same. Reference numerals are attached. The pad cover 1 shown in FIG. 4 is integrally molded by an injection molding machine by a two-color molding method. In this example, each vertical groove 5 forming the H-shaped tear line extends beyond the edge portion 7 to the end wall portion 3a, and the end portion of the vertical groove 5 is separated from the edge portion 7 by the distance L '. Extends down along. The distance L'between the end of the vertical groove 5 on the end wall 3a and the edge 7 is set to about 5 mm.

Further, the pad cover 1 is provided with a development promoting portion 10 similar to that of the first embodiment on the back surface of the end wall portion 3a,
The development promoting portion 10 is formed by a groove 11 having a U-shaped cross-section which is discontinuous with the vertical groove 5. The total length of the groove 11 is the vertical grooves 5, 5
, And each end of the groove 11 is located on an extension of the vertical groove 5, 5. The pad cover according to the first embodiment was manufactured as Example 1 and the pad cover according to the second embodiment was manufactured as Example 2 as shown in Tables 1 and 2 below. Further, the pad cover having the structure shown in FIG.
As a comparative example 2, a pad cover having the structure shown in FIG. 6 was manufactured as shown in Tables 1 and 2 below. Note that FIG.
And in FIG. 6, the same reference numerals are given to the same parts or members as those of the first and second embodiments. As apparent from FIGS. 5 and 6, the pad cover of Comparative Example 1 corresponds to the pad cover of Example 1 described above, and the pad cover of Comparative Example 2 corresponds to the pad cover of Example 2 described above.
It corresponds to the pad cover of. However, the pad covers of these comparative examples do not have any groove or the like that constitutes the above-mentioned expansion promoting portion.

[0021]

[Table 1]

[0022]

[Table 2] As another comparative example, the pad covers of Comparative Examples 3 to 5 were manufactured as follows. (1) Comparative Example 3 A pad cover molded by a two-color molding method, and the pad cover does not have any groove or the like that constitutes the above-mentioned expansion promoting portion. The distance between the connecting portion of the top surface portion and the end wall portion (corresponding to the edge portion 7) and the end portion of the vertical line (vertical groove 5) of the H-shaped tear line 4 arranged on the top surface portion (in the above distance L) Is equivalent to
It is set to 13 mm. (2) Comparative Example 4 A pad cover molded by a two-color molding method as in Comparative Example 3, and similar to the groove 11 of the expansion promoting section 10 as schematically shown in FIG. 7 (plan view). A groove 9 having a U-shaped cross section is provided in the top surface portion 2. The groove 9 is oriented substantially parallel to the lateral groove 6 of the H-shaped tear line 4 and is arranged inward of the respective ends of the longitudinal grooves 5 and 5. The length of the groove 9 is the vertical grooves 5, 5
It is set to be shorter by about 5 mm on each side (total about 10 mm) than the interval. The distance (corresponding to the distance L) between the edge portion 7 and each end portion of the vertical grooves 5, 5 is set to 13 mm. (3) Comparative Example 5 A pad cover molded by a two-color molding method. The pad cover has the same shape as the pad cover of Comparative Example 3, as shown in the partial perspective views and partial sectional views of FIGS. 8 and 9. No groove or the like that constitutes the expansion promoting portion, or a groove or the like similar thereto is provided at all. Vertical grooves 5, 5 of H-shaped tear line 4
Extends to the undercut portion 3c, and the distance L'between the edge portion 7 and the ends of the vertical grooves 5, 5 of the H-shaped tear line 4 is
It is set quite large (L '= 35mm).

The specifications of the pad covers of Comparative Examples 3 to 5 are shown in detail in the table below.

[0024]

[Table 3] Using the airbag system with the pad covers of Examples 1 to 2 and Comparative Examples 1 to 5 described above, an airbag deployment experiment was performed under uniform conditions in a cold atmosphere and a severe heat atmosphere, and an H-shaped tear was performed. The progress of cleavage along the line and the spread state of the cleaved cover part were confirmed. As a result of the airbag deployment experiment, the test results shown in Tables 1 to 3 above were obtained. That is, in the cold atmosphere (−40 ° C.), in the pad covers of Examples 1 and 2, tearing of the tear line proceeded to the end of the vertical line portion, that is, the end of the vertical groove 5, whereas Comparative Example 1 In the pad covers Nos. 5 to 5, the tear line did not reach the end of the vertical groove 5, and the tear stopped in the middle of the vertical groove 5. However, in the extremely hot atmosphere (90 ° C.), in the pad covers of Example 1 and Comparative Example 1, the cleaved cover part spreads out around the axis connecting the vertical line ends of the H-shaped tear line. In the pad covers of Example 2 and Comparative Example 2, tearing of the tear line proceeded to the end of the flute 5, so that substantially the same results were obtained in Examples 1 and 2 and Comparative Examples 1 and 2. . Moreover, in the pad cover of Comparative Example 5, in a severe heat atmosphere (90 ° C.), the cleavage proceeded beyond the end of the vertical line of the tear line, and the attachment portion of the pad cover was broken and scattered.

As is clear from the above test results, in the pad covers of Examples 1 and 2 according to the first and second examples, a cold atmosphere (-40 ° C.) and an extremely hot atmosphere (90 ° C.) were used.
In both cases, the cleavage along the longitudinal groove 5 of the H-shaped tear line progresses to the desired site, and the cleavage does not proceed beyond the desired region. In addition, in the above test, the cleaved cover portions in Examples 1 and 2 were cold atmosphere (-
Both in 40 ° C.) and in an extremely hot atmosphere (90 ° C.), the airbag was properly expanded without hindering the deployment of the airbag and without damaging or damaging the mounting portion.

From the test results of Comparative Examples 3 to 5 described above, the following was found. That is, even if the groove 9 similar to the groove 11 of the expansion promoting portion 10 is arranged on the top surface portion 2 (Comparative Example 4), the temperature is substantially the same as that without the groove 9 (Comparative Examples 3 and 5). Cleavage in the atmosphere of does not proceed sufficiently. Therefore, the deployment promoting portion 10 is substantially meaningless even if it is provided on the top surface portion 2, and needs to be provided on the side surface portion 3. Further, as is clear from the test results of Comparative Example 5, when the undercut portion 3c similar to the development promoting portion 10 is close to the end portion of the tear line 4, the cleavage excessively progressed in the high temperature atmosphere and the cleavage occurred. The cover part is scattered outward due to the expansion of the airbag. Therefore, it was found that the development promoting unit 10 needs to be separated from the tear line 4.

[0027]

As described above, according to the above-mentioned configuration of the present invention, the tear line is allowed to reach a desired portion regardless of the change of the ambient atmosphere, and the tear line is greatly exceeded the desired region. Therefore, it is possible to provide a pad cover for an airbag system which can smoothly and completely expand the split cover portion without advancing.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing a pad cover for an airbag system according to a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view of the pad cover shown in FIG.

3 is a cross-sectional view of the pad cover taken along the line AA of FIG.

FIG. 4 is a perspective view showing a pad cover for an airbag system according to a second embodiment of the present invention.

5 is a perspective view showing a pad cover according to Comparative Example 1. FIG.

FIG. 6 is a perspective view showing a pad cover according to Comparative Example 2.

7 is a schematic plan view showing a pad cover according to Comparative Example 4. FIG.

FIG. 8 is a partial perspective view showing a pad cover according to a comparative example 5.

9 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 1 Airbag system pad cover 2 Top surface part 3 Side part 3a End wall part 3b Side wall part 4 Tier line 5 Vertical groove 6 Horizontal groove 7 and 8 Edge part 10 Development promotion part 11 Groove

Claims (4)

[Claims] 1. An airbag system having a top surface portion and a side surface portion that form an airbag storage area of an airbag system, and a tear line that promotes tearing of a pad cover when the airbag is deployed is provided at least on the ceiling surface portion. In the pad cover, having a deployment promoting portion having a fragile portion discontinuous with the tear line, the fragile portion is arranged on the side surface portion at a position separated from the end portion of the tear line by a predetermined distance, A pad cover for an airbag system, which is oriented substantially parallel to a rotation axis which constitutes a rotation center of the cover portion when the cover portion which has been cleaved is deployed. 2. The pad cover for an airbag system according to claim 1, wherein the fragile portion has a groove arranged in a region substantially the same as the rotation axis. 3. The expansion promoting portion is arranged at a position within a range of about ¼ to ⅔ of the total height of the side surface portion, as measured from a connecting portion between the top surface portion and the side surface portion. The pad cover for an airbag system according to claim 1 or 2, wherein: 4. The distance between the weakened portion and the tear line is about 10 mm to 5 along the surface of the pad cover.
The pad cover for an airbag system according to any one of claims 1 to 3, wherein the pad cover is set to 5 mm.