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Cover for a vehicle air bag

Inactive Publication Date: 2000-10-03
TAKATA CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

An object of the present invention is to provide an air bag cover that has a surface that is soft and comfortable to the touch and in which a core under the surface layer holds its shape well under external loads for protection of the air bag. Another object is to provide a cover that is easily broken in a controlled manner when the bag inflates over a temperature range of from -40.degree. C. to

Problems solved by technology

The manufacture of air bags with reinforcing nets involves many steps, and it is difficult to make them with high accuracy, even when Reaction Injection Molding (RIM), is used, thus leading to a low yield rate

Method used

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  • Cover for a vehicle air bag
  • Cover for a vehicle air bag

Examples

Experimental program
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Example

EXAMPLES AND COMPARATIVE EXAMPLES

The examples of the invention given in Table I are merely illustrative and are not intended to limit the scope of the invention. The comparative examples (Table II) exhibit some of the deficiencies in the characteristics of covers that do not embody the invention.

In examples 1 to 11 and comparative examples 1 to 9, a core portion (1.0-3.0 mm thick) provided with slits (each about 0.7 mm long, 29 slits altogether) was injection-molded with a core material, as described below, using an in-line screw, two-color injection molding machine and a mold-clamping force of 350 tons, and then the surface layer injection-molded in the prescribed thickness over the core portion. Thus the air bag cover 1 shown in FIG. 1 was obtained.

In example 3 and 10, the surface layer was foamed. Foam molding was carried out by blending 5 parts of a CO.sub.2 -based foaming agent (Master Batch Fine Blow S20N, Mitsubishi Petrochemical Co., Ltd.) for each parts of the surface mater...

Example

In comparative example 10, an air bag cover consisting of a surface layer made of a high-density urethane foam and a core portion made of low-density urethane foam was made and evaluated. The core portion was molded by the RIM method at a low-foaming density and cured and then placed in a mold for forming the surface layer by insert injection molding. Freon gas was used as the foaming agent to foam the surface layer. This method required carrying out the curing process twice, thereby reducing the production rate.

Example

In comparative example 11, an air bag cover provided with a reinforcing net was made and evaluated. A woven net of polyester thread was cut so as to provide gaps corresponding to the zones of weakness of the cover. The net was inserted into a mold and the cover molded by the RIM molding method. Freon gas was used as a foaming agent. The cover was removed from the mold and cured at 100.degree. C. for 30 minutes. It was difficult to form a good skin layer with the net inserted.

The materials of the core layer and surface layer, the JIS-A hardness of the materials and the bending elastic modulus of the core layer material used in the examples and the comparative examples are set forth in Table I and Table II below.

TABLE I ______________________________________ (Examples of the Invention) Core Layer Surface Layer Exam. Bend Elas Hardness Hardness No. Mat'l Mod-kg / cm.sup.2 (JIS-A) Mat'l (JIS-A) ______________________________________ 1 PP-1 11000 100 TPS-1 45 2 PP-2 4000 99 TPO-2 65 3 PP-2...

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Abstract

A cover for a vehicle air bag comprises an external surface layer injection-molded from a thermoplastic material having a JIS-A hardness of 20 to 90 and a core layer injection-molded from a thermoplastic material having a bending elastic modulus (JIS K 7203) of not less than about 1000 kg/cm2 and a hardness greater than that of the surface layer. The core has weakened zones along which the cover breaks when the air bag is inflated.

Description

FIELD OF THE INVENTIONThe present invention relates to a cover for housing a folded vehicle safety air bag of the type that inflates virtually instantaneously upon the sensing of a rapid acceleration of the vehicle or some other event indicative of a collision of the vehicle and prevents the occupant from experiencing a secondary collision with parts of the vehicle, such as the steering wheel, dashboard or windshield, generally in front of him.BACKGROUND OF THE INVENTIONVehicle safety air bags are folded into a housing formed in part by a support that is attached to the vehicle, for example, the hub of the steering wheel, and to which the air bag is secured, and in part by a cover that is positioned generally between the folded air bag and the vehicle occupant. In a widely used type of air bag housing, the cover is made of a polymeric material and has weakened zones that enable it to break easily in a controlled manner when the air bag inflates, thereby enabling the air bag to emerg...

Claims

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Application Information

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IPC IPC(8): B32B27/08B60R21/20B60R21/2165
CPCB32B27/08B60R21/21656Y10T428/24983Y10T428/15B32B7/022B60R21/2165B32B2605/08B32B27/32B32B27/22
Inventor SAWADA, MASAMINANBU, YUICHIYOSHIYASU, MITSUO
Owner TAKATA CORPORATION
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