Automotive trim piece and method to form an air bag opening

• US 5,797,619 A
• Filed: 05/05/1997
• Issued: 08/25/1998
• Est. Priority Date: 01/30/1989
• Status: Expired due to Fees

• Current Assignee: TIP Engineering Group Incorporated
• Original Assignee: TIP Engineering Group Incorporated
• Inventors: Bauer, executor, John W. Jr., Bauer, deceased, David J.
• Primary Examiner(s): Culbreth, Eric D.
• Application Number:
  US08/851,413
• Time in Patent Office: 477 Days
• Field of Search: 280/728.3, 280/728.1, 280/732, 102/275.1, 102/275.8, 102/202.7, 83/875, 264/293
• US Class Current: 280/728.3
• CPC Class Codes: B29C 2035/0838 using laser
• CPC Class Codes: B29C 2793/0054 partially cutting through the material
• CPC Class Codes: B29C 2793/009 after shaping
• CPC Class Codes: B29C 59/007 Forming single grooves or ribs, e.g. tear lines, weak spots by moulding B29C37/0057; folding lines B29C53/06; in metal articles B21D17/00; by cutting B26D3/08
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29L 2031/3038 Air bag covers
• CPC Class Codes: B60R 2021/21652 the tearing being done or assisted by cutters
• CPC Class Codes: B60R 2021/21654 the tearing being done or assisted by heating or pyrotechnic means
• CPC Class Codes: B60R 21/2165 characterised by a tear line for defining a deployment opening
• CPC Class Codes: Y10T 83/0304 Grooving

Abstract

An arrangement for forming an opening in an auto interior trim panel or piece normally having no visible indication of the opening just prior to inflation of an inflatable air bag, allowing deployment of the air bag into the passenger compartment of vehicle, the arrangement including a linear element positioned below the skin of the trim panel or wheel cover in a pattern corresponding to the opening. In a first embodiment a heat generating element is employed as the linear element which when activated degrades the covering skin layer of the trim piece in pattern shape. In a second embodiment detonating cord enclosed in a metal tube is employed with a series of holes directing the energy of detonation to sever the panel skin material. In a third embodiment a split sleeve having explosive coating on the inside is used to create a flame front severing the panel skin in the appropriate pattern. The skin may be mechanically preweakened prior to assembly by a precision cutting operation performed on the inside surface, in a pattern matching with the pattern of the linear element, aiding the process of forming the opening in the trim piece at the instant of deployment.

Claims

1. A method of forming an air bag deployment opening within an expanse of a plastic covering layer of an interior trim piece extending within a passenger compartment of a vehicle, said deployment opening occupying a limited area of said expanse at a particular location within said covering layer expanse, said covering layer overlying a folded air bag stored behind said interior trim piece at said particular location, said covering layer smoothly and uninterruptedly overlying said particular location and adjacent regions of said interior trim piece, the method comprising the steps of preweakening the covering layer after the covering layer is first formed by cutting a groove extending partially into the inside of the covering layer in a deployment opening pattern, said deployment opening pattern occupying a limited area within said trim piece covering layer expanse;

and molding a supporting layer of foam against the inside of said covering layer including a region lying beneath said groove cut into the inside of said covering layer, whereby inflation of the air bag causes severing of the covering layer along the groove to form a deployment opening in said covering layer at said particular location within a greater expanse of said plastic covering layer.

2. The method according to claim 1 wherein said cutting step comprises the step of partially slitting a flat sheet of material which forms said preweakening pattern.

3. The method according to claim 1 further including the step of degrading said covering layer at the time of air bag deployment by the application of energy in a pattern at least approximating said preweakening pattern.

4. An instrument panel for the interior of an automobile passenger compartment equipped with an inflatable air bag device adapted to be deployed into a passenger space in said passenger compartment, said air bag device mounted at a particular location behind said instrument panel to normally be concealed from view from within said passenger space, said instrument panel comprising a structure fixed within said passenger space and including a covering having an outer surface exposed to view extending smoothly and uninterruptedly across said location of said air bag device so as to not provide an external indication of said air bag device location;

said instrument panel also including a supporting structure underlying said covering and providing continuous support beneath said covering extending across the boundary between the region of said air bag device location and the remaining area of said covering, said supporting structure including a substrate panel having a deployment opening formed therein;

a door panel fit into said substrate panel opening, said door panel hinged to move away from surrounding adjacent portions of said substrate panel when said air bag is deployed enabling said deploying air bag to pass through said opening in said substrate panel; and

,

weakening means located beneath the outer surface of said covering for weakening said instrument panel and extending in a deployment opening pattern lying over said deployment opening in said substrate panel, said deployment opening pattern lying within a limited area of said covering and disposed at said particular location of said air bag device, which deployment opening pattern is not visible from within said passenger space prior to activation of said air bag device, whereby said location of said air bag device behind said instrument panel is not visible from within said passenger space until air bag device activation occurs.

5. The instrument panel according to claim 4, wherein said weakening means includes a linear energy element extending in said pattern and adapted to degrade said covering when said air bag device is activated.

6. The instrument panel according to claim 4, wherein said weakening means includes a groove cut into an inside surface of a skin defining said covering, said groove extending corresponding to said deployment door pattern.

7. The instrument panel according to claim 6 wherein said supporting layer includes a continuous foamed plastic layer disposed immediately beneath said skin covering to provide said continuous support.

8. The instrument panel according to claim 6 wherein said instrument panel supporting structure includes a rigid deployment door panel and a main rigid substrate panel underlying said foam layer and having an opening formed therein, said deployment door panel fit into said opening.