Two piece plastic vehicle panel construction

A two piece vehicle panel construction is provided. The first and second piece of the vehicle panel are made by injection molding. The first and second piece cooperate to provide proper aesthetics, structural integrity, and increased sun load resistance. The proper positioning and alignment of the two piece construction is facilitated by at least two alignment fixtures that are nested within the first and second pieces.

BACKGROUND OF THE INVENTION 
 1. Technical Field 
 The present invention generally relates to plastic panels. More 
 particularly, the present invention relates to plastic vehicle panels that
 are comprised of more than one piece. More specifically, but without 
 restriction to the particular embodiment and/or use which is shown and 
 described for purposes of illustration, the present invention relates to a
 two piece injection molded vehicle panel that provides structural rigidity
 as well as an aesthetic appearance. 
 2. Discussion 
 A major trend in the automotive industry is to produce vehicles that are 
 lighter than previous vehicles. This is typically performed in order to 
 achieve the fuel economy benefits inherent in a lighter vehicle. Another 
 major trend in the automotive industry is to produce vehicles that are 
 less expensive to manufacture than its predecessors. This is performed in 
 order to increase the profit margin per vehicle sold in the marketplace. 
 The auto industry has been in a seemingly never-ending struggle to produce
 vehicles that are lighter and less expensive than previous vehicles. 
 Vehicle body panels have been in the flux of change in response to these 
 trends. Traditionally, vehicle panels have been made of steel or some type
 of composite material. The outside of the panel is typically painted and 
 the inside of the panel, those portions adjacent to the passenger cabin of
 the vehicle, are covered by a plastic trim piece in order to provide an 
 aesthetically pleasing surface for the passengers of the vehicle. Other 
 systems have also been utilized to provide a show surface on both the 
 interior and the exterior of the panel. 
 Injection molding of a plastic material has been a method for producing 
 parts that reduces the weight and cost of these type of panels. 
 Unfortunately, it is very difficult to provide injection molded plastic in
 a vehicle panel size sufficient for this type of application. It is 
 difficult to provide molds that are large enough to handle such a large 
 panel. In addition, it is difficult to achieve proper flow through such a 
 large area. This can lead to many problems, one major problem is 
 developing a show surface that is aesthetically pleasing. Typically, 
 larger panels of this type are made from materials or molding operations 
 that require paint to provide an aesthetically pleasing show surface. 
 Painting a panel adds considerable cost to the vehicle and is, therefore, 
 undesirable. Additionally, with injection molding panels, the panels are 
 typically removed with ejector pins which can cause marks on the on the 
 panels as they are still warm and malable from the injection molding 
 process. Not only is it difficult to produce large injection molded 
 plastic pieces, but it is also difficult to provide a plastic part that 
 produces a system that provides structural rigidity as well as an 
 aesthetic appearance acceptable for vehicle body panels. 
 There is, therefore, a need to provide large plastic panels that can be 
 used on a motor vehicle. Such a panel must meet certain ultra-violet 
 standards, strength standards as well as surface texture standards. There 
 is also a need to provide large plastic panels that possess structural 
 integrity as well as a textured or show surface on both the interior and 
 exterior surfaces such that it does not require paint to be aesthetically 
 pleasing. 
 SUMMARY OF THE INVENTION 
 Accordingly, it is a principal objective of the present invention to 
 provide a a vehicle panel system that provides a show surface on both the 
 interior and exterior of the panel. 
 It is another objective of the present invention to provide a two piece 
 injection molded system that can be effectively combined to produce a 
 panel with enough structural integrity to be utilized as a body panel for 
 a motor vehicle. 
 It is still another objective of the present invention to provide a plastic
 vehicle panel that will not deform with high temperature or sun loads. 
 In one form, the present invention provides a two piece vehicle panel made 
 by injection molding. The panel includes a first piece and a second piece.
 The first piece includes two longitudinally extending and parallel 
 structures and at least two cross members interconnecting the two 
 structures. The first piece also includes at least one downwardly 
 extending pillars that terminates in a base formation. The base formation 
 is adapted to be secured to the vehicle body via bolts, screws, clips, or 
 the like. The first piece has an inner surface that is suitable for 
 display and an outer surface that has portions thereof suitable for 
 display. The second piece includes a generally planar top surface that 
 attaches to the cross members of the first piece to provide support 
 thereto. The second piece also includes at least one projection extending 
 downward from the planar top surface that is cooperative with the 
 downwardly extending pillar of the first piece to create a structural 
 channel. The second piece has an outer surface that is suitable for 
 display and includes portions of its inner surface that are suitable for 
 display. 
 The planar top surface of the second piece is directly subjected to sun 
 load due to its relative position with the vehicle, while concealing the 
 cross members and the longitudinal structures from direct sun load. The 
 planar top surface includes a crown so as to prevent sink from prolonged 
 sun load. 
 Additional benefits and advantages of the present invention will become 
 apparent to those skilled in the art to which this invention relates from 
 a reading of the subsequent description of the preferred embodiment and 
 the appended claims, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
 Referring now to the drawings, there is depicted an assembled vehicle panel
 having structural rigidity and surfaces suitable for display on both sides
 embodying the concept of the present invention. FIG. 1 illustrates an 
 assembled vehicle body panel 10. Panel 10 is designed to be utilized as 
 the roof panel of a motor vehicle, such that the exterior surface 12 is 
 exposed to the environment and the interior surface 14 is exposed in the 
 vehicle cabin. Openings 16 and 16' are provided for the installation of a 
 rear quarter window (not shown). Edges 18 and 18' are designed to attach 
 to the lower portion of a vehicle body via screws or bolts. Panel 10, 
 preferably, attaches to a front windshield frame at its forward-most end 
 20. Panel 10 also has the ability for an opening rear window to attach to 
 it at its rearward-most end 22. Panel 10 is constructed from injection 
 molded plastic, preferably PET (polyethylene terephthalate), or a 
 Polypropelene/Polystyrene blend, or other structural polymer blends. 
 FIG. 2 and FIG. 3 illustrate vehicle body panel 10 disassembled. Panel 10 
 includes a first piece 24 and a second piece 26. First piece 24 has two 
 longitudinally extending structures 28 and 28' that are substantially 
 parallel. Forward cross-member 30, middle cross-member 32, and rearward 
 cross-member 34 interconnect structures 28 and 28' to create a framework 
 having a front opening 27 and a rear opening 29. Cross-members 30, 32, and
 34 are substantially parallel to one another. Extending downward from each
 of the junctions made by middle cross member 32 and longitudinally 
 extending structures 28 and 28' are forward pillars 36 and 36' (36' not 
 shown in FIG. 2). Extending downward from each of the junctions made by 
 rearward cross member 34 and longitudinally extending structures 28 and 
 28' are rearward pillars 38 and 38'. Rearward pillar 38 and forward pillar
 36 are connected on their lowest edge by base formation 40. Conversely, 
 rearward pillar 38' and forward pillar 36' are connected on their lowest 
 edge by base formation 40'. Base formations 40 and 40' extend along the 
 lower length of panel 10 and terminates in edge 18 and 18' that provides 
 attaching means to the vehicle body (not shown). The attaching means could
 be bolts, screws, clips, or adhesive. In the preferred embodiment, the 
 base formations 40 and 40' attach to the vehicle body via bolts (not 
 shown). The inner surface 42 of first piece 24 is all grained or textured 
 in some way. This provides surface 42 with aesthetically pleasing 
 attributes for a plastic material, thereby making inner surface 42 
 suitable for display. The outer surface 41 has portions 43 thereof 
 suitable for display as well. The first piece 24 provides structural 
 rigidity to the assembly 10. Base formations 40 and 40' attach to a 
 vehicle body to create a forward end 20 which attaches to a windshield 
 frame, these aspects along with the ladder structure formed by members 28,
 28', 30, 32, and 34 provide a structural part with strength to the vehicle
 panel 10 with a minimal amount of weight. Each plastic piece is produced 
 by an injection molding process. By utlizing an injection molded process 
 and the afore-mentioned materials, colored plastic can be produced by the 
 addition of a dye or resin to the raw plastic material. The plastic 
 material is heated and then forced under pressure into a mold space of a 
 mold. The plastic part ultimately takes the form of the mold space. Most 
 molds are made of steel or aluminum in order to provide the necessary heat
 transfer characteristics. Typically, the surface of the mold, that defines
 the mold space is sand blasted to create a textured or grained surface in 
 the mold. By creating such a textured or grained surface on the mold the 
 resulting plastic part produced from that mold will have a complimentary 
 textured or grained show surface. By graining the mold of an injection 
 molded part, the resultant surface will be suitable for display so long as
 ejector pins and the like do not contact this surface while the part is 
 still malable. The first piece 24 is formed in a mold having a top 
 component and a core component that define the top and bottom surfaces of 
 the mold space. The top component is adapted to vertically raise after the
 molding process. It should be appreciated that portions of the top 
 component that contact the mold space are grained. The core component is 
 outfitted with horizontal lifters that contract within said core component
 to effectively unlock the first piece 24. It should further be appreciated
 that the core component that forms the inner surface 42 of the first piece
 24 is completely grained. The first piece 24 can then be lifted off by 
 hand or by some other means such as by suction cups or straps. It should 
 also be appreciated that numerous slides are provided in the components to
 aid in ejecting the completed piece from the mold. 
 The second piece 26 of the vehicle panel 10 is designed to attached to the 
 first piece. The second piece includes an outer surface 45 having 
 generally planar top surface 44 and two downwardly extending projections 
 46 and 46'. Projections 46 and 46' are suitable to attach to rearward 
 pillars 38 and 38'. The inner surface 48 of second piece 26 includes two 
 substantially rectangular portions 50 and 52 of grained or show surface, 
 as best illustrated in FIG. 3. The remaining portions 53 of the bottom 
 surface are not grained. It can be appreciated that grained portions 50 
 and 52 cooperate with openings 27 and 29 of first piece 24 so as to 
 provide an interior surface 14 of panel 10 that is grained. The second 
 piece 26 attaches to the exterior of the first piece 24. The second piece 
 26 substantially covers the first piece 24 except for the portions 43 
 thereof that are suitable for display. The entire outer surface 45 of the 
 second piece is suitable for display. It can be appreciated that the first
 piece 24 and the second piece 26 not only cooperate to produce complete 
 show surfaces but also complement each other structurally. Second piece 26
 is disposed over the first piece 24 such that a channel 49 is formed in 
 the rear pillars 38 of the vehicle. Channel 49 is bound on one side by 
 rearward pillars 38 and 38' and the other side by projections 46 and 46'. 
 This type of arrangement provides strength to the rear pillars. The second
 piece 26 is formed in a mold having a top component and a core component 
 that define the top and bottom surfaces of the mold space. The top 
 component is raised vertically to remove the piece from the mold. It 
 should be appreciated that the top component that forms the outer surface 
 45 of the second piece 26 is completely grained. After the top component 
 is raised, ejector pins are activated on the core component to lift or 
 disengage the piece from the core component of the mold. The ejector pins 
 do create surface marks that compromise the appearance of the piece, 
 therefore, the ejector pins are disposed on portions 53 of the second 
 piece 26 that are not visible when panel 10 is assembled. Thereby allowing
 the complete interior surface 14 of panel 10 to be grained and suitable 
 for display. It should be appreciated that the first and second piece are 
 adapted to cooperate to produce an assembled panel that has an interior 
 surface 14 and an exterior surface 12 that is suitable for display. 
 Turning to FIG. 4, a cross-sectional view along a bonding surface is 
 provided. The inner surface 42 of the first piece 24 is exposed in the 
 cabin of the vehicle and is grained. The outer surface 41 is illustrated 
 with grained portion 43 as well as a bonding surface 56 that is not 
 grained. The outer surface 45 of the second piece 26 is grained. The inner
 surface 48 illustrated in FIG. 4 as the portion 53 that is not grained in 
 this locale. The first piece 24 includes a grained portion 43 adjacent to 
 an attaching platform 58. Platform 58 is disposed a distance 60 from the 
 grained portion 43 slightly greater than the thickness of the second piece
 26, as defined by numeral 62. It should be appreciated that platform 58 is
 disposed substantially along the joint 61 between the first piece 24 and 
 the second piece 26. First piece 24 includes at least one standoff 64 
 having a height 66. Standoff 64 extends from a surface 56 of the outer 
 surface 41 not suitable for display. Surface 56 is disposed a level below 
 platform 58. It can be appreciated that the height 66 of standoff 64 is 
 slightly larger than the distance 70 that surface 56 is disposed below 
 platform 58. Adhesive 72 is disposed such that it contacts the portion 53 
 of the inner surface 48 of the second piece that is not grained and the 
 surface 56 of the outer surface 41 of the first piece 24 that is not 
 grained. The height 66 of standoff 64 is preferably equivalent to the 
 minimum bonding thickness of the adhesive 72. It can also be appreciated 
 that the attaching platform 58 acts as a glue damn to limit the flow of 
 adhesive toward the exterior surface 12 of the assembled panel 10. It 
 should be appreciated that the first piece 24 and the second piece 26 can 
 be attached by various means such as clips, bolts, screws, and the like. 
 FIGS. 5A and 5B illustrate the rear alignment fixture needed to position 
 the first piece 24 and the second piece 26 in proper position with respect
 to each other. There are, preferably, two alignment fixtures 74 and 76, as
 shown in FIGS. 2 and 3. Alignment fixture 74 is disposed at the 
 forward-most end 20 of the panel 10 and fixture 76 is disposed at the 
 rearward-most end 22 of the panel 10. Alignment fixture 76 is disposed in 
 a nested arrangement with the first piece 24 and the second piece 26 such 
 that when panel 10 is assembled, neither alignment fixture is visible on 
 the interior 14 or exterior 12 surface. The inner surface 48 of second 
 piece 26 carries a pair of skis 89 and 89' disposed a distance 80 apart. 
 The inner surface 42 of the first piece 24 carries a projection 82. 
 Projection 82 includes a central formation 84 and two side formations 86 
 and 86' each interconnected by an outboard angled ledge 88 and 88'. Each 
 Ski 89 and 89' is designed to cooperate with an angled ledge 89 and 89' 
 such that central formation 84 contacts the inner surface 48 of the second
 piece 26. This provides an alignment between the first piece 24 and the 
 second piece 26 as shown in FIG. 5B. Alignment fixture 74 at the 
 forward-most end 20 of the panel 10 is illustrated in FIG. 9. It should be
 appreciated that the inner surface 42 of the first piece 24 carries two 
 formations 95 and 97 to hold skis 99 therebetween. Each formation 95 and 
 97 includes an inboard angled ledge 93 for contacting the skis 99. It 
 should be appreciated that the skis 89 and 89' of the rear fixture 76 are 
 disposed to span the central formation 84 while the skis 99 of the front 
 formation are disposed between formation 95 and 97. 
 During the injection molding process, plastic material is introduced into 
 the mold space by an injector head. At the placement of the injector head 
 the plastic is typically marked in some way due to the inherent 
 differences between the injector head and the surrounding mold. These 
 differences are typically temperature differences and parting line 
 creation between the head and the mold. This will typically lead to 
 formation similar to mark 92 shown in FIG. 6. The top surface 44 of the 
 second piece 26 includes a plurality of longitudinally extending 
 depressions 90 formed thereon. As is shown, the injector head is position 
 in a depression 90 to help conceal the unsightly mark. 
 FIG. 7 illustrates the forward most end 20 of the assembled panel 10. The 
 second piece 26 includes a teardrop structure 94 extending to cover the 
 front edge 96 of the first piece 24. This design limits wind noise created
 from panel 10 as the vehicle is in motion. Without the teardrop 94 wind 
 may flow against joint 98 causing wind noise and possible early 
 deterioration of joint 98. 
 FIG. 8 illustrates a cross sectional view of vehicle panel 10. Second piece
 26 is designed with a crown of sufficient degree. The crowning of the 
 second piece 26 creates an outward movement of said piece as the 
 surrounding temperature is increased. Typically, a plastic material 
 increases in size as the temperature increases. In a vehicle setting, the 
 second piece 26 will increase in temperature due to sun load and will 
 therefore expand. However the first piece 24, not shown in FIG. 8, will 
 not expand as significantly because it is not directly affected by sun 
 load. By the nature of the two piece vehicle panel construction as the 
 outer panel expands, it is still held in place at certain attachment 
 locations to the first piece. Therefore, the expansion that occurs 
 increases the degree of the crown. Other plastic vehicle panels have not 
 been designed with a similar two piece construction with the 
 aforementioned crown, therefore, as the temperature increases due to sun 
 load, the panel tends to sink or form a depression therein. After repeated
 sun loads, the part may form to that sunken shape that will pool water and
 other unsightly articles on the top of the vehicle panel. 
 While the above description constitutes the preferred embodiment of the 
 invention, it will be appreciated that the invention is susceptible to 
 modification, variation, and change without departing from the proper 
 scope or fair meaning of the accompanying claims.