MANUFACTURING PROCESS FOR CONCEALED OPENING OF SUPPLEMENTAL RESTRAINT SYSTEM AIR BAG DOORS FOR USE IN AUTOMOBILE INTERIORS

Abstract: A method for providing an interior vehicle trim panel (10) having a pre-weakened door location for the deployment of supplemental restraint system air bag. The method includes the step of embedding a reinforcing member (25) having a removable tear strip within the structure of the trim panel skin (12). After the skin is cured, the tear strip is removed through the interior surface (22), creating a gap (30) therein which defines the door location. The reinforcing member supports the skin structure surrounding the pre-weakened site upon deployment of the air bag.

Description: MANUFACTURING PROCESS FOR CONCEALED OPENING OF SUPPLEMENTAL RESTRAINT SYSTEM AIR BAG DOORS FOR USE IN AUTOMOBILE INTERIORS Technical Field This invention pertains to the art of methods for manufacturing vehicle trim panels, and more specifically to methods for manufacturing a vehicle trim panel having a concealed air bag door therein. Background Art Automotive vehicles have long utilized restraint systems for the safety of vehicle passengers. Initially, such restraint systems included seat belts which fit over the occupant's lap. Later many restraint systems were modified to add an additional strap, or shoulder harness, which crossed the occupant's chest and further protected them against impacts. Of late, air bag supplemental restraint systems have become increasingly popular. A typical air bag supplemental restraint system includes an inflatable bag which is stored in a deflated condition within the vehicle steering wheel or trim assembly. Upon a relatively severe impact to the vehicle, the air bag is rapidly inflated and deployed into the vehicle passenger compartment through various means and openings. Early air bag deployment systems included a requirement that the opening through which the air bag would be deployed was weakened or somehow configured to insure its successful deployment. Usually the weakened areas were thin spots or cuts in the vehicle interior trim components. The cuts were visible to the vehicle occupants and they detracted from the appearance of the vehicle interior. As such, a need arose for an effective air bag deployment system which was obscured or hidden from the view of vehicle occupants until such deployment. U.S. Pat. No. 5,072,967 to Batchelder et al. discloses a cover assembly for an air bag restraint which has a smooth cover. An outer cover member has weakened sections on an inboard surface to facilitate deployment of the air bag through the opening created thereby. To reduce the probability of such weakened sections being visible to vehicle occupants, a filler material is placed between the weakened outer cover member and an insert to prevent inward collapse of the outer cover member at the weakened sections . In addition, an insert of aluminum is formed in the filler material and, upon deployment of the air bag, is stressed against the weakened sections of the cover member to deploy the air bag. The invention of U.S. Pat. No. 5,072,967 to Batchelder et al is a more complicated system than that of the invention. U.S. Pat. No. 5,082,310 to Bauer discloses an arrangement enclosure for an air bag deployment opening to be formed in the interior trim structure of an automotive vehicle. The closure includes a substrate section which is weakened in a pattern to form contiguous doors or subsections which split apart along purportedly invisible seams when an air bag is inflated. Upon such inflation, the resulting pressure on the inside of the opening causes the preweakened skin of the foam plastic layer to split apart along the seams, allowing the air bag to be deployed into the vehicle interior. This arrangement requires the skin of the foam plastic layer to be weakened in a matching pattern above the seams in the substrate section. It is believed that the embodiment of U.S. Pat. No. 5,082,310 to Baueris also more complicated than the present invention and requires that the outer skin of the vehicle interior be weakened over a substantial portion of its area for proper deployment of the air bag. Disclosure of Invention A method for producing a motor vehicle interior trim panel having a door through which an enclosed air bag supplemental restraint system may be deployed is provided. The panel has an outer skin with an exterior surface designed to be viewed by an occupant in the vehicle. The interior surface of the skin includes a pre-weakened site, or tear seam, which defmes the door location. Upon deployment of the air bag, the skin tears along the tear seam and the door is displaced. The location of the door is concealed from the occupants of the vehicle. One advantage to the present invention is improved control of the depth of the tear seam in the skin. Another advantage of the present invention is the reinforcement of the door and the surrounding skin. Another advantage of the present invention is the integral hinge for the door. Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification. Brief Description of Drawings The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein: Fig. 1 shows an interior vehicle trim panel according to the invention. Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1. Fig. 3 is a side sectional view of a vehicle trim panel showing the displacement of a door due to air bag deployment. Fig. 4 is a bottom view of the skin of a vehicle trim panel according to the invention. Fig. 5 is a bottom view of a skin assembly being built in a mold. Fig. 6 is a side sectional view of the skin assembly of Fig. 5. Fig. 7 is a side sectional view of the cured skin. Detailed Description of the Invention Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting the same, Fig. 1 shows a vehicular trim panel 10 through which a supplemental restraint system air bag may be deployed upon impact of the vehicle with another object. As shown in Fig. 2, the vehicle trim panel 10 may incorporate several components including an outer skin 12, an adhesive foam backing 14 and an underlying substrate 16. In accordance with the present invention, the skin 12 of the vehicle trim panel 10 includes an exterior surface 20 which may be viewed by the occupants of the vehicle and an interior surface 22 which is obscured from view from the perspective of the vehicle occupants. The skin 12 further includes a reinforced area 24 bounded by dashed line 24A in Fig. 1, due to the presence of an embedded reinforcing member 25. The reinforced area 24 of the skin 12 includes a section which is displaced upon deployment of the air bag. The section of the skin 12 which is displaced is referred to as a door 26, having a perimeter designated by dashed line 26 A. In the preferred embodiment, the door 26 is completely surrounded by the reinforced area 24. With reference again to Fig. 2, in the preferred embodiment, the interior surface 22 is gaped at a pre-weakened site, or tear seam, 30 which corresponds to at least a first portion 34 of the perimeter of door 26. The reinforcing member 25 is likewise not continuous along this first portion 34. In a preferred embodiment of the present invention, an occupant of the vehicle is unable to detect the pre-weakened site 30 of the interior surface 22 of the skin 12 by viewing the exterior surface 20. Substrate 16 has an opening therein which is generally vertically aligned with the perimeter 26A of door 26. An interior door 35 closes the opening and maintains an air bag within a canister located beneath the opening as illustrated by the dashed line in Fig. 2. Upon deployment of the air bag, the interior door 35 is upwardly displaced. The interior door 35 is formed of a rigid material such as aluminum or steel. With reference to Fig. 3, in a preferred embodiment, the interior surface 22 and the reinforcing member 25 are continuous along a second portion 36 of the perimeter of door 26. The part of the reinforcing member 25 which corresponds to the second portion 36 of the perimeter of door 26 acts as a hinge 40 to direct the displacement of the door 26 upon deployment of the air bag. The hinge 40 further prevents door 26 from completely separating from the remainder of the skin 12 but rather the door 26 swings out of the way of the deploying air bag. Because the reinforced area 24 of the skin 12 completely surrounds door 26, the skin 12 outside the door 26 is strengthened against damage by a deploying air bag. In a preferred embodiment, the interior door 35 is attached to substrate 16 along the side which vertically corresponds to the second portion 36 of the perimeter of door 26. Upon deployment of the air bag, the interior door 35 likewise swings out of the way, but remains attached to substrate 16. Referring to Fig. 4, in a further embodiment, the pre-weakened site 30 of the interior surface 22 may be coated with a mold release material 42 which prevents any adhesive foam backing 14 of the vehicle trim panel 10 from adhering to the pre-weakened site 30 and possibly hindering the displacement of door 26. A preferred method for manufacturing a vehicle trim panel 10 in which the skin 12 comprises a concealed pre-weakened site 30 in an interior surface 22 will now be described. Generally, a skin assembly is built and cured in a first mold. To build the skin assembly, a first half of the mold used to form the skin 12 is coated with a first layer of skin material. A preferred method for coating the first half of the mold comprises spraying a two component poly-urethane system into the mold. As shown in Fig. 5, a first area of the first layer 46 is overlaid with a reinforcing member 25. The reinforcing member 25 may comprise fabric, metallic mesh, or polymeric material such as polyester scrim. Attached to the reinforcing member 25 is a tear strip 50. The tear strip 50 may be formed of materials similar to that which may be used in the reinforcing member 25. The tear strip 50 is aligned where at least a first portion 34 of the perimeter of the door 26 will be and thereby defines the door location. After the reinforcing member 25 and the associated tear strip 50 are applied to the first layer 46 of skin material, the first half of the mold is coated with a second layer 54 of skin material. As shown in Fig. 6, the second layer 54 of skin material covers the reinforcing member 25 and the tear strip 50. In a preferred embodiment, attached to the tear strip 50 is a protruding tab 58 to enable the tear strip to be readily removed from the cured skin 12. After the skin assembly is built, the assembly is cured by methods that are common in the art. The cured skin 12 comprises an exterior surface 20 which is able to be viewed by occupants of the vehicle and an interior surface 22 which is obscured from vie . The reinforcing member 25 and the tear strip 50 are embedded within the cured skin 12. The tab 58 extends from the interior surface 22. The cured skin 12 is removed from the mold and the embedded tear strip 50 is removed by pulling the tab 50 which protrudes from the interior surface 22. As shown in Fig. 7, a portion of the interior surface 22 corresponding to the first portion 34 of the door's perimeter is thereby removed. A gap is created in the interior surface 22 thereby creating the pre-weakened site 30. The removal of the tear strip 50 also effectively forms a gap in the reinforcing member 25 at least along the first portion 34 of the door's perimeter. In other words, the reinforcing member 25 is not continuous after removal of the tear strip 50. The exterior surface 20 of the cured skin 12 remains intact. In a preferred method, the tear strip 50 does not extend along a second portion 36 of the door's perimeter. After the skin 12 is cured, and the tear strip 50 removed, the interior surface 22 is not pre-weakened along that second portion 36 of the door's perimeter. Likewise, the reinforcing member 25 remains continuous along the second portion 36 of the door's perimeter. Upon deployment of the air bag, the skin 12 will tear along the pre-weakened site 30 which corresponds to the first portion 34 of the door's perimeter but not along the reinforced second portion 36. Instead, the door will rotate outwardly along the second portion 36. Therefore, the reinforcing member 25 acts as a hinge 40 to direct the displacement of the door 26 upon air bag deployment. The reinforcing member 25 further acts to prevent the door 26 from separating from the remainder of the skin 12. After removal of the tear strip 50, the skin 12 may be used in the formation of a vehicle trim panel 10 by methods known in the art. One such method includes a secondary curing operation of a vehicle panel assembly which incorporates a foamed adhesive backing 14 and substrate 16. In order to prevent the foamed adhesive 14 from adhering to the skin 12 in the pre-weakened site 30, and thereby possibly hindering the displacement of the door 26, a mold release material 42 may be applied to the interior surface 22 along the pre- weakened site 30 before subsequent processing. The preferred embodiments and methods have been described, hereinabove. It will be apparent to those skilled in the art that the above methods may incorporate changes and modifications without departing from the general scope of this invention. It is intended to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof. Having thus described the invention, it is now claimed:

Claims: CLAIMS 1. A method for producing a tear seam in a vehicle trim panel, the tear seam being obscured from view by occupants of the vehicle, the method characterized by the steps of: coating a first half of a mold with a first layer of skin material; overlaying an area of the first layer of skin material with a reinforcing member, the reinforcing member having a removable tear strip attached thereto, the tear strip defining a door location; coating the first half of the mold with a second layer of skin material after overlaying the area of the first layer with the reinforcing member; curing the first and second layers of skin material to form a skin of the vehicle trim panel, the skin having an exterior surface able to be viewed by the occupants of the vehicle and an interior surface; and, removing a portion of the interior surface of the cured skin at the door location and leaving the exterior surface intact. 2. The method of claim 1 wherein the tear strip includes a tab which protrudes from the interior surface of the cured skin and wherein the step of removing a portion of the interior surface comprises removing the tear strip from the cured skin by pulling the tab. 3. The method of claim 1 wherein the step of coating the first half of the mold with a first layer of skin material comprises spraying a two component poly-urethane system into the first half of the mold. 4. The method of claim 1 further comprising the step of backing the interior surface of the cured skin with an adhesive foam material. 5. The method of claim 4 further comprising the step of coating the interior surface of the cured skin with a mold release material at the door location before the step of backing the interior surface with the adhesive foam material. 6. A method for producing a concealed door in a vehicle trim panel, the method characterized by the steps of: building a skin assembly having an embedded reinforcing member, the reinforcing member being attached to a removable tear strip, the tear strip corresponding to at least a first portion of the perimeter of the door; curing the skin assembly in a first mold to form a cured skin, the cured skin having an exterior surface and an interior surface; weakening the interior surface of the cured skin along the first portion of the perimeter of the door; building a trim panel assembly in a second mold; and, curing the vehicle trim panel. 7. The method of claim 6 wherein the step of building a skin assembly comprises: coating a first half of the first mold with a first layer of skin material; overlaying an area of the first layer with the reinforcing member; coating the first half of the mold with a second layer of skin material after overlaying the area of the first layer with the reinforcing member. 8. The method of claim 6 wherein the step of weakening the interior surface of the cured skin along the first portion of the perimeter of the door comprises removing the tear strip by pulling it through the interior surface to form a gap therein. 9. The method of claim 6 wherein the step of building a trim panel assembly comprises: placing a mold release material on the interior surface of the cured skin along the first portion of the perimeter of the door; placing the skin into a first half of the second mold; placing a substrate in a second half of the second mold; and, injecting an adhesive foam material into the closed mold. 10. A skin assembly for use in an interior vehicle trim panel, the skin assembly characterized by: a first layer of skin material; a second layer of skin material; a reinforcing member embedded between the first and second layers, the reinforcing member defining a reinforced area of the skin assembly; and, a tear strip attached to the reinforcing member, the tear strip defining at least a first portion of a door perimeter, the door perimeter being completely surrounded by the reinforced area. 11. The skin assembly of claim 10 further comprising: a tab attached to the tear strip and extending therefrom through the second layer of skin material. 12. The skin assembly of claim 10 wherein the skin material comprises a sprayable polyurethane system. 9608\gyr2029.pa6 13. The skin assembly of claim 10 wherein the reinforcing member comprises a metallic mesh. 14. The skin assembly of claim 10 wherein the skin material comprises polymeric material. 15. The skin assembly of claim 11 wherein the skin material comprises a sprayable polyurethane system.

Inventors: MACGREGOR CLINE JAY, MACGREGOR, CLINE, JAY
Applicants: GOODYEAR TIRE & RUBBER, MACGREGOR CLINE JAY, MACGREGOR, CLINE, JAY, THE GOODYEAR TIRE AND RUBBER COMPANY
Application year: 1996
Main classification: B60R21
IPC codes: B60R21