Abstract:
According to the present invention, an instrument panel cover for use in an instrument panel of a vehicle compartment having a supplemental inflatable restraint (SIR) system and a method for manufacturing the instrument panel cover are provided. The instrument panel cover includes a body having an inner surface and an opposing outer surface, the body having an air bag cushion deployment region formed in the inner surface thereof, the deployment region being defined by at least one score formed in the inner surface to a predetermined depth, wherein the at least one score is formed by at least one scoring member which contacts the instrument panel cover during the manufacture thereof and the advancement of the at least one scoring member causes the instrument panel cover to thin out in predetermined locations which define the at least one score. Because the present invention incorporates the scoring process into the process for forming the instrument panel cover, the present invention advantageously eliminates the need of secondary scoring of the air bag door seam and therefore provides cost benefits and a reduction in processing and manufacturing times.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to an instrument panel, seat, pillar, door panel or steering wheel used in a vehicle having a supplemental inflatable restraint (SIR) system, and more particularly to an instrument panel cover having an integral hidden air bag door and a method of manufacture thereof.  
         BACKGROUND OF THE INVENTION  
         [0002]    As more and more vehicles are equipped with SIR systems, other vehicle components have been modified to accommodate the use of such systems. For example, most SIR systems are disposed within and behind an instrument panel which extends across the width of a vehicle compartment. Generally, a vehicle instrument panel comprises a plurality of layers including a panel cover, a foam layer, and a substrate. The cover is typically disposed adjacent the foam layer which is disposed, correspondingly, adjacent to the substrate, thus forming the panel.  
           [0003]    Traditionally, an instrument panel employed in a vehicle equipped with a SIR system utilizes a discrete door which covers an opening formed in the instrument panel for the air bag cushion to deploy through upon actuation of the SIR system. This separate door is designed to open in response to the force of the expanding air bag cushion. As the pressure in the air bag cushion increases, a force is generated on the door. The door then selectively separates from the remaining portion of the instrument panel to permit the air bag cushion to deploy.  
           [0004]    Typically, the manufacture of a conventional instrument panel involves two separate processes and a final assembly step. First the instrument panel is formed in view of the shape and size of the door with an opening adjacent to the SIR system. Meanwhile, in a separate process the door is formed using techniques known in the art. Finally, the air bag door is assembled onto the instrument panel for use in conjunction with the SIR system. The plurality of steps involved in the manufacture of the conventional instrument panel consume substantial time and resources and result in an aesthetically apparent air bag door.  
           [0005]    Recent advances in the art teach a vehicle instrument panel that utilizes a hidden deployment region integrally formed within an inner surface of the instrument panel to provide a panel of less weight and without the obvious markings of an air bag door. The deployment region of such panels comprises a plurality of scores or cuts formed in the inner surface of the instrument panel. The scores represent weakened portions of the instrument panel designed so that the force of an inflating air bag cushion causes the instrument panel to separate along the scores to thereby provide an opening for the inflating air bag cushion to deploy therethrough and be directed into the passenger compartment of a vehicle.  
           [0006]    The manufacture of vehicle instrument panels with integrally formed hidden air bag doors typically involves three distinct processes. First, the various layers of the panel are cast using methods common in the art. Then, a blade is brought into contact with the various cast layers of the panel to melt and/or cut into the interior surface of the layers forming the scores and cuts necessary to allow deployment of the concealed air bag. Finally, the layers are adhered together in such a way as to construct the panel.  
           [0007]    Vehicle instrument panels with integral hidden air bag doors eliminate the use of components and processes involved with the manufacture of separate air bag doors and result in a hidden deployment region that is completely concealed from observation by vehicle occupants thereby permitting the outer surface of the instrument panel cover to have a stylistically uniform appearance. However, methods of manufacturing the instrument panel typically involve a scoring process independent of the processes involved in casting the panel itself thereby introducing an additional step to the instrument panel manufacturing process which consumes time and resources better allocated to other areas in the art.  
         SUMMARY OF THE INVENTION  
         [0008]    According to the present invention, an instrument panel cover for use in an instrument panel of a vehicle compartment having a supplemental inflatable restraint (SIR) system and a method for manufacturing the instrument panel cover are provided. The instrument panel cover includes a body having an inner surface and an opposing outer surface. The body has an air bag cushion deployment region formed in the inner surface thereof. The deployment region is defined by at least one score formed in the inner surface to a predetermined depth, wherein the at least one score is formed by at least one scoring member which contacts the instrument panel cover during the manufacture thereof. More specifically, the at least one score is formed in-process during the formation of the instrument panel cover itself.  
           [0009]    In one exemplary embodiment, the instrument panel cover is formed using a female vacuum forming tool with a plug assist. The plug is fitted with a cylinder which can be actuated in any number of ways including by air. Attached to the cylinder are at least one blade which is extendable and retractable relative to the plug so that during the forming of the instrument panel cover using the plug assist, the at least one blade may be extended into the instrument panel cover to form the at least one score. When the at least one blade is extended into the instrument panel cover, it effectively thins out the skin (instrument panel cover) to create a weakened region which comprises the air bag seam. Therefore, the at least one blade may have any number of shapes and of different patterns (e.g., V, H, U, C, Y, I, etc.) to make the desired air bag seam pattern depending upon the requirements.  
           [0010]    According to the present invention, the cylinder is actuated immediately after the forming process while the skin (instrument panel cover) is still hot and the cylinder is lowered down to thin-out the air bag door seam. The cylinder is then retracted to its original position so that a bottom edge thereof is sub-flush with a lower surface of the plug. The skin is then cooled and demolded from the tool resulting in the at least one score being formed in the skin during the manufacture of the skin itself. The tool is ready for the next cycle. The skin formed by the vacuum process is then foamed in-place using conventional foaming techniques with a substrate (retainer), which is already thinned out for the air bad door seam. Preferably, the thinning of the retainer for the air bag door is done in the injection molding process. Accordingly, the retainer is thinned out in-process (in the injection molding) as well.  
           [0011]    The present invention eliminates the need of a secondary operation of scoring the air bag door seam in the instrument panel skin and a finished instrument panel part is obtained from the foaming process. Other advantages are that the elimination of the secondary scoring operation is eliminated and hence a cost benefit is realized. The process can also use an in-process thinned-out retainer to eliminate the scoring of the retainer as a secondary operation as well. The process eliminates read-through of the air bag seam on the Class A surface of the instrument panel skin and hence gives a high quality part. The Class A surface of the instrument panel skin is the surface which faces the passenger compartment and is desired to be smooth and free of defects. Also, the scoring process is in-process which gives consistent seam position and depth of the seam and thus gives consistent performance.  
           [0012]    The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The present invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0014]    [0014]FIG. 1 is a perspective view of an exemplary vehicle instrument panel embodying the present invention;  
         [0015]    [0015]FIG. 2 is a side elevation view of a vehicle instrument panel according to the present invention;  
         [0016]    [0016]FIG. 3 is a side elevation view of a vehicle instrument panel cover and a manufacturing device;  
         [0017]    [0017]FIG. 4A is a schematic illustration of an adjustment system of the manufacturing device of FIG. 3;  
         [0018]    [0018]FIG. 4B is a schematic illustration of another embodiment of an adjustment system;  
         [0019]    [0019]FIG. 5 is a cross-sectional view of an exemplary vehicle instrument panel cover showing scoring thereof by the manufacturing device;  
         [0020]    [0020]FIG. 6 is a partial enlarged cross-sectional view of the vehicle instrument panel cover and manufacturing device of FIG. 5;  
         [0021]    [0021]FIG. 7 is a partial cross-sectional view of the scoring of the vehicle instrument panel cover;  
         [0022]    [0022]FIG. 8 is a cross-sectional view of the vehicle instrument panel cover showing the score formed therein according to the present invention;  
         [0023]    [0023]FIG. 9 is a top plan view of an exemplary vehicle instrument panel embodying the present invention;  
         [0024]    [0024]FIG. 10 is a cross-sectional elevation view of the vehicle instrument panel of FIG. 9 along the axis  10 - 10  of FIG. 9;  
         [0025]    [0025]FIG. 11 is a cross-sectional elevation view of the vehicle instrument panel of FIG. 3 disposed in a manufacturing device; and  
         [0026]    [0026]FIG. 12 is a cross-section view of another embodiment of the vehicle instrument panel of FIG. 3 disposed in a manufacturing device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    Referring to FIG. 1, an instrument panel in accordance with the present invention is illustrated and generally indicated at  10 . The instrument panel  10  is assembled into a vehicle passenger compartment  12  beneath a windshield  14  and extending across substantially the entire width of the passenger compartment  12 . According to the present invention, and as will be described in greater detail herein, the instrument panel  10  includes an instrument panel cover  16  having a deployment region  18  formed therein, wherein the deployment region  18  is defined by a plurality of cuts or scores  20  on the interior of the panel  10 . The deployment region  18  is intended to be the general area in which a passenger side SIR system (not shown) is proximately disposed thereto and deployed through during actuation thereof under predetermined deployment conditions. FIG. 2 illustrates a cross-sectional view of a portion of one exemplary instrument panel  10 . The instrument panel  10  includes the instrument panel cover  16  disposed adjacent to a foam layer  21  which is disposed, correspondingly, adjacent to a substrate  22 .  
         [0028]    [0028]FIG. 3 illustrates the instrument panel cover  16  in a first stage prior to forming the deployment region  18  therein. The instrument panel cover  16  in the first stage includes an inner surface  24  and an outer surface  26 . Accordingly, the thickness of the instrument panel cover  16  may be thought of as the distance between the inner surface  24  and the outer surface  26 . The instrument panel cover  16  is formed of any number of suitable materials and, in an exemplary embodiment, the instrument panel cover  16  is formed of a thermoplastic material. For example, suitable thermoplastic materials include but are not limited to polyethylene based polyolefin elastomer or polypropylene based thermoplastic elastomer. Preferred materials are those which have the desired characteristics of strength, flexibility, and finished appearance and feel for use as an instrument panel  10 . The instrument panel cover  16  is mounted in the vehicle so that the outer surface  26  is visible to a vehicle occupant and the inner surface  24  forms a contact surface for the foamed surface above air bag cushion, which is generally indicated at  32  in FIG. 1. The air bag cushion  32  is part of the SIR system and is positioned so that the air bag cushion  32  is adjacent the substrate  22  of the instrument panel assembly  10 .  
         [0029]    In the first stage, represented in FIG. 3, the instrument panel cover  16  is disposed in a manufacturing device  28 . The device  28  is an apparatus common in the art for forming the instrument panel cover  16 . The device  28  includes a vehicle instrument panel vacuum forming tool  30 . The tool  30  generally acts as a mold which receives the thermoplastic material of which the cover  16  is composed. The tool  30  includes a receiving surface  34  and a mounting surface  36 . The receiving surface  34  is contoured in accordance with the desired shape and size of the particular instrument panel cover  16 . The receiving surface  34  receives the thermoplastic material to form the cover  16  and retains and molds the material by means of vacuum suction as is known in the art. The mounting surface  36  is generally disposed upon a casing (not shown) to facilitate use of the device  28 .  
         [0030]    The device  28  further includes a rack  38  disposed above the receiving surface  34  of the tool  30  and a plug assist  40  disposed on the rack  38  extending downward towards the receiving surface  34 . The plug assist  40  facilitates in the molding of the cover  16  according to conventional techniques. The device  28  also includes a cylinder  42  disposed within the plug assist  40 . The cylinder  42  includes at least one contact edge  43  for cutting or scoring the instrument panel cover  16  as described herein. The at least one contact edge  43  may have any one of a variety of cross-sectional shapes. For example, the at least one contact edge  43  may have the cross-sectional configuration of a “U”, “V”, or of any rectilinear or curvilinear shape. The contact edge  43  may be independent of the cylinder  42  or may be disposed integrally therewith and may be of any longitudinal shape sufficient for scoring the cover  16 . Further, several contact edges  43  may be arranged on the cylinder  42  so as to form any of a variety of patterns which may be pressed into the instrument panel cover  16 , as is discussed further herein. For example, a plurality of contact edges  43  may be arranged on the cylinder  42  to form an “H”, “I”, “O”, “T”, “U”, “V”, square, rectangle, triangle, etc.  
         [0031]    The temperature of the cylinder  42 , the at least one contact edge  43 , and the plug assist  40  may each be controlled as is necessary to properly form the instrument panel cover  16  and to score the cover  16  in-process in accordance with the present invention. For instance, the temperature of the cylinder  42 , the at least one contact edge  43 , and the plug assist  40  each may be maintained to replicate room temperature or raised to the temperature of the instrument panel cover  16 , etc. Additionally, the temperature of the cylinder  42 , the at least one contact edge  43 , and the plug assist  40  each may be increased to a temperature above the instrument panel cover  16 .  
         [0032]    The cylinder  42  is disposed in communication with an adjustment system  44  which may be utilized by an operator or which may be actuated automatically to retract the cylinder  42  into the plug assist  40 , as is shown in FIG. 3, or to extend the cylinder  42  beyond the plug assist  40  thus engaging the instrument panel cover  16 , as is shown in FIG. 5.  
         [0033]    [0033]FIG. 4A shows a schematic representation of the adjustment system  44 . In a preferred embodiment, the adjustment system  44  is pneumatically based and includes a compressed air supply  46  disposed adjacent to a selector switch  48  which is disposed communicatively with the cylinder  42 . The compressed air supply  46  provides the adjustment system  44  with a predetermined pressure and volume of compressed air. The selector switch  48  includes indicia  51  corresponding to the various predetermined positions of the cylinder  42 . The indicia  51  may be numerals such as  1 ,  2 , etc.  
         [0034]    In an alternative embodiment of the present invention, shown in FIG. 4B, an adjustment system  45  may actuate automatically, without the operator, by means of a controller  49  that positions the cylinder  42  within the device  28  (FIG. 3) according to a set of predetermined criteria. In such an embodiment, the adjustment system  45  may utilize an electronic, hydraulic, pneumatic means, or any other suitable means to maneuver the cylinder  42  as described above.  
         [0035]    The method, in one embodiment of the present invention, of scoring the instrument panel cover  16  to form an integral hidden air bag door therein during the manufacturing process of the instrument panel cover  16  begins with the application of the thermoplastic material to the vacuum forming tool  30  as shown in FIG. 3. The thermoplastic material is applied to the receiving surface  34  of the vacuum forming tool by conventional methods in such quantity as desired to form an instrument panel cover  16  of a predetermined thickness. The thermoplastic material is held in position and shaped atop the receiving surface  34  by suction means provided by the tool  30 . The plug assist  40  is operated in accordance with the art.  
         [0036]    Referring to FIGS. 4A and 5, when desired, an operator may actuate the cylinder  42  by manipulating the selector switch  48  from a first position to a second position hence commanding the adjustment system  44  to maneuver the at least one contact edge  43  towards the inner surface  24  of the instrument panel cover  16 . The at least one contact edge  43  accordingly engages the inner surface  24  of the instrument panel cover  16 , passing therethrough toward the outer surface  26  a prescribed distance ‘d’ (see FIGS. 6 and 7). When desired, the operator may return the selector switch  48  to the first position causing the adjustment system  44  to retract the at least one contact edge  43  from the instrument panel cover  16  as is depicted in FIG. 8. The first position and the second position may be represented by the indicia  51  and, in an exemplary embodiment, may be depicted by the numerals one (1) and two (2), respectively. It will be appreciated that contact edge  43  can be in a fixed position and not be retracted or extended if the design permits for a given application.  
         [0037]    Referring to FIGS. 3 and 4B, as is mentioned above, an alternative embodiment of the invention may include the adjustment system  45  fully automated by the controller  49 . In such an embodiment, the adjustment system  45  would include a monitoring means (not shown) that would monitor the device  28  and the instrument panel cover  16  for certain predetermined criteria. Upon detection of such criteria by the monitoring means, the controller  49  actuates the cylinder  42  and maneuvers it as described herein above thus scoring the instrument panel  16  in-process. Criteria upon which the controller  49  may actuate the cylinder  42  may include, for example, time, temperature of the instrument panel cover  16 , temperature of the vacuum forming tool  30 , etc.  
         [0038]    Upon retracting the cylinder  42 , the score  20  is formed in the instrument panel cover  16  as shown in FIG. 8. The score  20  has a depth of the predetermined distance ‘d’ and is shaped in accordance with the cross-sectional shape of the at least one contact edge  43  of the cylinder  42  as is discussed herein above. The score  20  creates a narrowed section  46  in the instrument panel cover  16  of a predetermined thickness ‘t’. The thickness ‘t’ is the distance from the inner surface  24  to the outer surface  26  of the instrument panel cover  16  less the predetermined distance ‘d’. The narrowed section  46  represents a weakened portion of the instrument panel cover  16  that yields under the pressure created by an inflating air bag which deploys therethrough as discussed herein.  
         [0039]    According to the present invention, the cylinder  42  may be actuated immediately after the forming process while the skin (instrument panel cover  16 ) is still hot and the cylinder  42  is lowered down and contacts the instrument panel cover  16  to thin out the air bag door seam and form the score  20 . Because the scoring process is incorporated into the manufacturing of the instrument panel cover  16 , the score  20  is easily formed in the instrument panel cover  16  because the skin is still hot and easily formable. Once the cylinder  42  is retracted, the instrument panel cover  16  is cooled and demolded from the device  28 .  
         [0040]    [0040]FIG. 9 illustrates a top view of the instrument panel cover  16  after being scored. Several scores  20  comprise the deployment region  18 . FIG. 10 is a cross-sectional view of the instrument panel  16  along an axis  10 - 10  of FIG. 9.  
         [0041]    After forming and in-process scoring, the instrument panel cover  16  is moved into a second stage, depicted in FIG. 11, wherein the instrument panel cover  16  is assembled with the foam layer  21  and the substrate  22  to form the instrument panel  10 . The substrate  22  includes the deployment region  18  comprised of a plurality of scores  19 . In the second stage, the instrument panel cover  16  and the substrate  22  are placed in a foaming tool  50  and foamed-in-place as is known in the art, thus adhering the instrument panel cover  16  to the foam layer  21  and the foam layer  21  to the substrate  22  to form the instrument panel  10 . Once assembled, the instrument panel  10  is then removed from the foaming tool  50  and installed adjacent the air bag  32  in the vehicle compartment  12  of the vehicle as shown in FIG. 1.  
         [0042]    [0042]FIG. 12 shows an alternative embodiment of a vehicle instrument panel  100  in accordance with the present invention. The instrument panel  100  includes the instrument panel cover  16  disposed adjacent to the substrate  22 . The instrument panel cover  16  is formed and receives scores  20  to create the deployment area  18  as taught above with reference to FIGS.  3 - 5 . The substrate  22  is manufactured with the scores  19  in the deployment region  18  in a separate injection molding process. The instrument panel  100  is assembled by adhering the inner surface  24  of the instrument panel cover  16  to the substrate  22  in a device  150  known in the art. The device  150  may be, for example, a vacuum cladding device or any device suitable for adhering the instrument panel cover  16  with the substrate  22  to form the instrument panel  100 .  
         [0043]    Referring to FIGS. 5 and 12. It will be understood that the plug assist  40  may be unnecessary in the formation of some vehicle instrument panel covers  16  and that the present invention is not limited to the those instrument panel covers  16  that utilize the plug assist  40  in their manufacture. Where the manufacture of an instrument panel cover  16  does not utilize the plug assist  40 , the cylinder  42  may be disposed upon the rack  38  or upon some other suitable housing proximate the instrument panel cover  16  so that the cylinder  42  may be used in accordance with the method of the present invention. The plug assist  40  may be utilized in the device  28 , even where its presence is not required to form the instrument panel cover  16 , to mount the cylinder thereupon to facilitate in-process scoring of the instrument panel cover  16  as taught herein.  
         [0044]    The present invention eliminates the need of a secondary operation of scoring the air bag door seam in the instrument panel composite skin and a finished instrument panel part is obtained from the foaming process. Other advantages are that the elimination of the secondary scoring operation is eliminated and hence a cost benefit is realized. The process can also use an in-process thinned-out retainer to eliminate the scoring of the retainer as a secondary operation as well. The process eliminates read-through of the air bag seam on the Class A surface of the instrument panel skin and hence gives a high quality part. The Class A surface of the instrument panel skin is the surface which faces the passenger compartment and is desired to be smooth and free of defects. Also, the scoring process is in-process which gives consistent seam position and depth of the seam and thus gives consistent performance.  
         [0045]    It will be understood that a person skilled in the art may make modifications to the preferred embodiment shown herein within the scope and intent of the claims. While the present invention has been described as carried out in a specific embodiment thereof, it is not intended to be limited thereby but is intended to cover the invention broadly within the scope and spirit of the claims.