JPH0415145A - Storage cover for air bag device - Google Patents

Abstract

PURPOSE:To obtain a storage cover which is lightweight especially as the whole of an air bag device by integrally molding a surface layer and an inner layer, and providing the surface layer with a channel along a break line portion planned, and the inner layer with slits along the break line portion planned and an expanded fulcrum axis portion. CONSTITUTION:A surface layer 5 made from a thermoplastic elastomer [I] of brittleness temperature less than -30 deg.C, 100% tensile stress 10 or 150kg/cm<2> and JISA hardness 35 or 85 is molded integrally with an inner layer 6 made from a thermoplastic elastomer [II] or a thermoplastic resin [III] of 100% tensile stress higher than that of the thermoplastic elastomer [I]. The surface layer 5 is provided with a channel 8 along a break line portion 5 planned and the inner layer 6 is provided with slits 10, 11 extending along the planned break line portion 7 and an expanded fulcrum axis portion 9, respectively. Thereby a storage cover is surely broken and expanded and also the cost of the cover is reduced and it is made easier to assemble and/or remove the cover and the whole device is made compact.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a system for restraining and restraining an occupant to the seat side in the event of a collision of a high-speed moving object such as a car, and controlling the occupants of the high-speed moving object such as a control device, an instrument panel, etc. This invention relates to a storage cover for an airbag device designed to protect against secondary collisions.

[Prior Art] An air pack device is attached to the front of an occupant of a fast-moving vehicle such as a car, and in principle, a gas generator operates to instantly generate gas in the event of a collision, etc. A bag stored in a sealed space and connected to a gas generator is filled with generated gas, and the storage cover ruptures due to the pressure of the bag, expanding and releasing the bag to the front of the passenger, restraining the passenger to the seat side.
This is a device to protect passengers from secondary collisions with control equipment, instrument panels, etc., which prevents them from being injured.

Therefore, in order to instantly and reliably release the hack in the event of a collision, etc., the storage cover of the air pack device must be able to reliably rupture and deploy, and must not scatter any debris that could injure the occupants. be done. (Instantaneous usually means several milliseconds to several tens of milliseconds.) Such storage covers have been proposed in Japanese Patent Application Laid-open No. 55-110643, Japanese Patent Application Laid-Open No. 1-202550, and others, and are already known.

For example, Japanese Patent Laid-Open No. 55-110843 discloses a storage cover having a structure in which a reinforcing material such as a strip partially covered with a woven fabric is embedded and molded into an elastic material. However, when manufacturing such a storage cover, it takes time and effort to set the reinforcing material, and the yield rate of obtaining a molded object in which the reinforcing material is embedded in the planned position with precision is low, leading to low productivity and low production. There is a drawback which is the yield.

Further, Japanese Patent Application Laid-Open No. 1-202550 proposes a storage cover having a structure in which a surface layer of soft resin and an inner layer of hard resin are integrally molded, and a tearing slit is provided in the inner layer. Such storage covers are soft and comfortable even when the occupant hits them while driving, but in order to achieve this, the thickness of the surface layer made of soft resin must be increased by the thickness of the inner layer made of hard resin. Therefore, the pressure of the pressurized bag must be high in order to rupture the surface layer of soft resin along the planned rupture line. It requires a large and heavy gas generator containing a large amount of gas generating agent, and
In some cases, there may be drawbacks such as the part corresponding to the planned break line only stretches but does not break. Furthermore, the part of this storage cover that corresponds to the line connecting the planned end of the break line and the end of the break line will become the expansion fulcrum axis of the cover piece after being broken, but this part is not connected to the surface layer made of soft resin. Because it is integrally molded with the inner layer made of hard resin,
The back pressure must be extremely high in order to instantly spread the cover piece into a petal shape after the cover is broken, which also has the disadvantage of requiring a very large and very heavy gas generator. .

[Problems to be Solved by the Invention] The first requirement that the storage cover of an airbag device should have is that when a high-speed moving object receives an impact of more than 100 yen, the gas generated instantaneously in the gas generator The storage cover must be able to break and expand reliably so that the expanding bag can be released in the direction of the passenger, and the storage cover must not be destroyed by the explosive force of the bag, causing debris to scatter and injuring the passenger. It is. And this requirement is 130
It is necessary to reliably achieve this in an operating atmosphere of .degree. C. to +80.degree.

Secondly, the storage cover itself has high productivity and low cost.
Furthermore, it is necessary that the air pack device be easy to assemble and easy to remove for inspection and the like. This second requirement is particularly important in mass-produced automotive airbag systems.

Thirdly, from the standpoint of fuel efficiency and comfort, not only the storage cover itself but also the entire airbag system including the gas generator must be as light as possible, compact, and have excellent decoration, feel, and durability. is necessary.

With respect to these requirements, conventional techniques have had problems as described above. That is, the problem that the present inventors are trying to solve is to provide a storage cover that satisfies all of the above requirements, and in particular, the air pack device as a whole is lightweight.

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the surface layer and the inner layer are integrally molded, and grooves are formed in the surface layer along the planned breaking lines. The inventors have found that it is effective to provide slits in the inner layer along the planned break line and the deployment fulcrum axis, leading to the present invention.

That is, the present invention provides (1) a storage cover for an air pack device that is attached to the front surface of an occupant of a high-speed moving vehicle, which has an embrittlement temperature of 130°C or less and a 100% tensile stress of 10 kg/
A surface layer made of a thermoplastic elastomer [1] having a hardness of ca+2 to 150 kg/am2 and a JISA hardness of 35 to 85; An inner layer made of resin [ll11] is integrally molded, the surface layer is provided with grooves along the planned break line, and the inner layer is provided with slits along the planned break line and the deployment fulcrum axis. This is a storage cover with a

Although the present invention has the above-mentioned technical matters as essential components, preferred embodiments include the following.

(2) A storage cover that has the basic structure described in (1) above and has intermittent slits in the inner layer. (3) (1)
) or the structure described in (2) above, in which at least a part of the slit provided along the axis of the expansion fulcrum planned in the inner layer is filled with the thermoplastic elastomer [1] of the surface layer. Storage cover (4) The above (1,), (1) in which voids are provided in at least part of the surface layer and/or the inner layer by gas injection molding method.
2) Storage cover described in (3) (5) At least the surface on the passenger side is covered with a coating film cured by light and/or heat (1), (2), (3) above. ,(4
) (-The present invention will be described below with reference to FIGS. 1 to 3.)
This will be explained in detail with reference to the drawings. FIG. 1 is a plan view of an airbag device attached to a control device of a high-speed moving body. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is a sectional view taken along the line BB in FIG. 1.

The storage cover 1 is attached to the part 2 of the airbag device by known means such as riveting, screwing, fitting, adhesive, etc. (It is attached with screws 4 via metal fittings 3).

The storage cover 1 is integrally formed with a surface layer 5 and an inner layer 6, and the surface layer is provided with a groove 8 along the planned break line portion 7, and the inner layer is provided with a groove 8 along the planned break line portion 7 and the planned break line portion 7. A slit 10.
11 are provided.

When a high-speed moving object receives an impact of a certain amount or more, the gas generator 12 instantaneously generates a large amount of gas based on the output from the impact sensor (not shown), and the gas is stored in the closed space (A). A bag 13 connected to the generator 12 is filled with gas, and the bag 13 is momentarily pressurized. The storage cover 1 has a break line 7 planned on its surface layer with a groove 8.
The bag is torn apart along the line, is pushed out by the expanding bag, and is expanded into a petal shape around the planned expansion fulcrum axis 9, releasing the bag to the front of the passenger.

The surface layer 5 of the storage cover has an embrittlement temperature of 130°C or less,
100% tensile stress or 10kg7cm2 to 150kg/
Cm 2 and is made of a thermoplastic elastomer [1] with a JIS A hardness of 35 to 85.

The embrittlement temperature of the thermoplastic elastomer [1] is such that when the airbag device is operated in an atmosphere of -30°C to +80°C in which the storage cover is attached and used, the storage cover will reliably prevent debris from scattering. It is essential that the temperature be below -30°C in order to be able to break, expand, and instantly release the bag. And the 100% tensile stress is 10kg/cI
If it is less than I', it will be fragile and the storage cover will have poor durability.
If it exceeds 50kg/cm2, it will be too strong and will break and develop, making it difficult to use, so 10kg/c@' or more is 150kg/cm.
'Must be less than or equal to. Furthermore, the hardness of the thermoplastic elastomer [1] is desirably 35 to 85 according to JIS A in order to provide a comfortable storage cover that feels good when touched by a passenger. The feeling of hardness when touching the storage cover 1 varies depending on the hardness and thickness of the elastomer forming the surface layer 5, the hardness and thickness of the elastomer or resin forming the inner layer 6, the dimensions of the storage cover 1, etc. be.

For example, the following experimental example clearly shows how material thickness and underlying material affect hardness.

Experimental Example 9. A JIS K 6301 doll hardness tester was attached to the auxiliary device of the hardness tester capable of applying a constant load of 81N, and Toughtic E 2051 (styrene-diene elastomer) was placed on the metal stand of the auxiliary device. To Asahi Kasei Industries,
The thermoplastic elastomers [I] include: styrene-diene elastomer, syndiotaftic 1,2 polybutadiene elastomer, trans 1,4 polyisoprene elastomer.
Styrene/olefin elastomer, olefin elastomer (including blend type and partially crosslinked type)
, polyester elastomer, polyamide elastomer, polyurethane elastomer, vinyl chloride elastomer, fluorine elastomer, blend type elastomer based on these, low density ethylene resin, ethylene vinyl acetate resin, ethylene ethyl acrylate resin, styrene acrylic acid resin. Ionomer, ethylene ionomer Blend type resins based on these are included.

The grooves provided in the surface layer can be provided on the passenger side and/or the opposite side of the surface layer (in the figure, the opposite side to the passenger). The cross-sectional shape of the groove may be any shape such as a 7-shape, a U-shape, or a circular arc, and the depth of the groove should be determined based on the rigidity, durability, breakability, expandability, and dimensional variation during molding of the storage cover as a whole. It is preferable to make it as deep as possible with consideration.

The inner layer 6 of the storage cover 1 is necessary in order to ensure that the storage cover 1 breaks and expands with as low pressure as possible, has rigidity as a whole, and is as lightweight and compact as possible. The thermoplastic elastomer [I11] constituting the surface layer 5 must be a thermoplastic elastomer [[] or thermoplastic resin [I11] having a rigidity higher than 100% tensile stress.

The thermoplastic elastomer [IN] may be a thermoplastic elastomer whose 100% tensile stress is higher than that of the thermoplastic elastomer constituting the surface layer, regardless of whether it is the same or different from the above thermoplastic elastomer [I], and
As the thermoplastic resin [III], styrene resin, AS
Examples include thermoplastic resins such as resins, ABS resins, methacrylic resins, vinyl chloride resins, olefin resins such as high-density polyethylene and polypropylene, polyamide resins, polyacetal resins, thermoplastic polyester resins, and thermoplastic polyurethane resins. It will be done.

In addition, the inner layer 6 has a break line portion 7 (indicated by a dotted line in FIG. 1) on the surface layer in order to ensure that the storage cover 1 breaks and expands at the lowest possible pressure and does not scatter broken pieces. It is necessary to provide a slit along the expansion fulcrum axis 9 (indicated by a dashed line in FIG. 1).

The shape of the slit provided along the planned breaking line may be any shape such as a U-shape, an 8-shape, a 7-shape, a T-shape, a cross shape, a radial shape, etc. (in the figure, a 8-shape).

The shape of the slit provided along the planned deployment fulcrum axis is approximately a line connecting the ends of the broken line (a straight line in the figure).

In addition, the embrittlement temperature in the present invention is determined according to JIS K 7216.
．． 100% tensile stress is Tsuki S K 8301.3 dumbbell, tensile speed 500 mm/min, hardness is JIS K
This is a value measured by 6301 A type.

Embodiment Embodiment Embodiment 1 will be described in more detail below with reference to FIGS. 4 to 6. FIG. 4 is a plan view of the air hack device, FIG. 5 is a sectional view taken along the line AA in FIG. 4, and FIG. 6 is a sectional view of the storage cover taken along the line BB in FIG. 4.

In the storage cover 1, a planned breaking line portion 7 is arranged in a figure 8 shape, and a planned expansion fulcrum axis line portion 9 is disposed intermittently.

The inner layer 6 is made of polypropylene (M881 manufactured by Asahi Kasei Kogyo).
9) It is molded using the gas injection molding method, and voids 15 are formed in the thick part to prevent uneven thickness (sink marks) during molding.
Weight reduction is planned.

In addition, a slit 10 is provided in a portion corresponding to the fracture line portion 7, and a slit 1 is provided in a portion corresponding to the deployment fulcrum axis portion 9.
1 is provided. Also, a plurality of bolts 3 for attaching the storage cover 1 are embedded and molded,
This bolt 3 and nut (not shown) attaches it to the part 2 of the airbag device so as to cover the bag 13 connected to the gas generator.

The surface layer 5 is made of Toughtic E 2081) manufactured by SEB Thermoplastic Elastomer Kasei Kogyo Co., Ltd., and is integrally molded in close contact with the inner layer 6 by a multi-layer molding method. A groove 8 having a V-shaped cross section is provided on the side opposite to the passenger along the planned break line portion 7, and when the air pack device is activated, the break line portion 7 breaks along this groove 8. , the storage cover is expanded into a petal shape using the expansion fulcrum axis line part 9 as the expansion axis, and the bag is released.

Furthermore, as Example 2, the passenger side surface of the storage cup (-) of Example 1 was coated with a soft urethane paint (Duranate E405 manufactured by Asahi Kasei Industries as an NGO component, Acrylic Polyol A manufactured by Dainippon Ink and Chemicals Co., Ltd. as an OH component). 801
) was applied and dried and cured at 80°C for 1 hour. After the obtained storage cover was left at room temperature for 2 days, the covered surface was rubbed with gauze soaked in xylene, and no change in appearance was observed. Slight swelling was observed on the uncoated surface.

[Effects of the Invention] The storage cover of the present invention has: (1) a embrittlement temperature on the surface layer of 130°C or less, and a 100% tensile stress of 10 kg/cm 2 to 150;
kg/cm', and a highly rigid thermoplastic elastomer [n] or thermoplastic resin [III] is used for the inner layer. By providing a groove in the surface layer and a slit in the corresponding inner layer, ■ By making the planned deployment fulcrum axis essentially composed of thermoplastic elastomer [II], reliable rupture can be achieved at extremely low pressure. Therefore, it is possible to avoid embedding reinforcing materials such as woven fabric or woven net, and it can be stably produced by the multi-layer injection molding method, which has high production speed and production yield. Not only the cover itself but also the entire airbag device can be made lightweight and compact.

In addition, (1) the surface layer and the inner layer are integrally molded and are in close contact with each other, so when the air pack device operates in an operating atmosphere of 130°C to 80°C, it does not scatter debris that could injure the occupants.

Furthermore, the use of a thermoplastic elastomer [I] with a JIS human hardness of 35 to 85 for the surface layer has resulted in a more favorable feel.

By coating the surface layer, decorative properties and durability can be brought to a more desirable level.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the air pack device of the present invention attached to a steering wheel, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 is a sectional view taken along line B-B in Fig. 1. 4 is a plan view of an air pack device shown as an embodiment of the present invention, FIG. 5 is a sectional view taken along line A-A in FIG. 4, and FIG. 6 is a plan view taken along line A-A in FIG.
A sectional view of the storage cover taken along line B. 1...Storage cover 5...Surface layer, 6...Inner layer, 7
...Planned break line portion, 8...Groove, 9...Planned deployment fulcrum axis line portion, 10.11...Slit, 12...Gas generator, 1
3...Back. Patent applicant: Asahi Kasei Industries, Ltd.

Claims (2)

[Claims] (1) A storage cover for an airbag device that is attached to the front of an occupant of a high-speed moving vehicle, with an embrittlement temperature of -30°C or lower and a 100% tensile stress of 10 kg/cm^2 to 150
kg/cm^2, and the JIS A hardness is 35 to 8.
The surface layer is made of a thermoplastic elastomer [I] with a tensile stress of 5 and the thermoplastic elastomer [I] has a tensile stress of 100%.
An inner layer made of a higher thermoplastic elastomer [II] or a thermoplastic resin [II] is integrally molded, and the surface layer has grooves along the planned fracture line, and the inner layer has grooves along the planned fracture line. A storage cover characterized in that a slit is provided along a break line portion and a deployment fulcrum axis line portion. (2) Claim No. 1, characterized in that the surface of the surface layer is coated with a coating film cured by light and/or heat.
Storage cover described in ).