Abstract:
A rigid cover assembly for covering the rear cargo compartment of a pickup truck. There is a tip plastic sheet that may have an acrylic surface placed over it for improved visual appearance. A bottom plastic sheet conforms to the shape of the top plastic sheet and is joined around the perimeter to the top plastic sheet. There is a fiberglass layer that is placed on the inside surface of the top and bottom plastic sheets that provides a bonding means for attaching a honey comb structural layer to the fiberglass layers. This provides light weight structural strength to the cover. The honeycomb that is attached to the plastic sheets reduces wetness marks.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is based on and claims priority of provisional patent application 60/724,475 filed Oct. 6, 2005, the disclosure of which is incorporated herein by reference. 

   BACKGROUND 
   This invention relates to tonneau covers for the cargo compartment of pickup trucks. 
   Pickup trucks have rectangular shaped beds at the rear of the vehicle, generally with a pivoting tailgate that pivots downwardly and in a rearward direction to a flat, horizontal plane that is generally in the same plane as the floor of the bed. Pickup trucks are used for numerous purposes for hauling all types of articles, that vary in size, shape and weight. At times it is beneficial that the bed be covered to protect the articles being transported. 
   Various covers have been used in the past. There are essentially two types of tonneau covers: flexible and rigid. One type is comprised of flexible covers including canvas, other fabrics, and flexible vinyl covers. The flexible cover is secured to the pickup truck by ropes, flexible cords, and other straps that are secured by hooks, ties, snaps, and other fasteners or attached to frames that are mounted on the pickup truck. A disadvantage of these types of covers is that they are extremely time consuming to put in place and secure to the truck, with a similar amount of time required to remove them. Due to the flexible characteristics of the cover, they can allow water to pool in low spots, rather than run off and onto the ground. Due to their lack of structural strength, they do not permit the user to install other items, such as racks, onto the flexible cover and provide minimal security. 
   As an alternative to a flexible cover, a second type of tonneau cover has gained popularity. These are rigid covers comprised of one piece rigid covers and multi-piece sectional rigid covers. Fiberglass, metal, and rigid plastic covers have been introduced and are usually pivotally connected to a frame or brackets mounted to the front and sides of the pickup truck bed. These allow the user to raise the cover from the rear of the bed, place the items in the bed, and lower the cover to protect the items. Generally hinges or other connectors are used to connect the cover to the truck bed or truck body. These connections are not readily or easily removed if the cover is to be removed for additional storage space. A disadvantage of these types of covers is their weight and the durability of the aesthetics of their top surface. Another disadvantage is complexity of installing and aligning the frame or brackets to the pickup truck bed. 
   Many of the rigid covers are made of two joined pieces or shells of plastic, such as illustrated in U.S. Pat. No. 6,547,310 issued to Myers. This patent illustrates a plastic cover that has supporting or reinforcing ribs placed across the bottom side of the cover. This design has several disadvantages that are found in all covers using a supporting ribbed structure. One disadvantage is that when a user wants to add an option or attachment to the cover, the mounting is made more difficult due to the rib structure. In all other areas of the cover, the thickness of the sheet precludes making a strong and solid attachment. Depending on where the attachment is made, a bolt, screw, or other fastener may be passing through only a thin portion of the cover or could be passing through the top surface and the generally hollow rib structure. Thus, the user is restricted to where he or she can mount the accessory. 
   Another disadvantage of this type of plastic tonneau construction is that it requires some form of reinforcing rib on the underside of the cover for structural rigidity. An example of this is seen in U.S. Pat. No. 6,340,194 issued to Muirhead et al. This patent illustrates a cover made from two sheets of heat deformable plastic material instead of using fiberglass reinforced plastic. The bottom panel has reinforcing ribs for additional strength. This reinforcing structure creates lines (“witness marks”) that are easily or at least partially visible to the observer on the top side of the cover. In extreme temperatures or when condensate forms due to humidity and temperature changes, the lines on the cover are even more obvious. 
   This type of plastic tonneau also has a non uniform, and generally not even under surface due to the reinforcing rib structure. If the underside is not even, it makes it difficult to satisfactorily attach carpet or other sheet materials to the under or bottom surface and also makes it difficult to mount accessories. These materials are preferably maintained flat against the underside of the cover for appearance reasons. 
   Yet another disadvantage of the two piece ribbed designs that have large areas between places where the two pieces are bonded together is that differential thermal expansion and contraction on the top cover piece often causes cracking, peeling, bowing, or other deformation of other surface imperfections, of paint applied to the top surface. This construction has large areas on the top shell that are not rigidly bonded to the bottom shell. The non-bonded areas of the top shell thermally expand and contract at a different rate than the areas of the top shell that are bonded to the bottom shell. This thermal expansion and contraction result in cracking and bowing which lead to cracking and peeling of the paint on the top surface of the top shell and other undesirable surface effects. 
   SUMMARY OF INVENTION 
   Applicant&#39;s invention is a two-piece cover that is constructed from a top sheet and a bottom sheet. The top sheet is made from a co-extruded sheet with an acrylic or thermoplastic polyolefin top layer over a plastic layer, such as polycarbonate and acrylonitrile butadiene styrene, or other suitable material with UV stabilizers. The bottom sheet is also made of a plastic, such as polycarbonate and acrylonitrile butadiene styrene, or other suitable material. There is a honeycomb structure between the top and bottom sheets. A layer of resin is applied to the inside of the top and bottom sheets. Then a layer of fiberglass is placed between the layers of resin and the top and bottom sheets are joined together with the honeycomb structure securely mounted between the sheets and the outer perimeter of the two sheets are bonded together with an adhesive. 
   OBJECTS AND ADVANTAGES 
   It is an object of the invention to provide a lightweight pickup truck cover that is made from a top and a bottom sheet with a honeycomb structure disposed between the two sheets. It is another object to provide a cover that securely bonds the honeycomb structure to the top and bottom shells so that the bond will not easily be broken. A related object is to provide a cover that has sound deadening properties due to the creation of dead air space between the two layers. 
   It is another object to provide a cover that has a first fiberglass layer disposed between the top cover and the honeycomb structure and a second fiberglass layer disposed between the bottom cover and the honeycomb structure. 
   It is still another object to provide a cover that has a smooth top surface over substantially the entire visible surface of the top sheet. 
   Still another object is to provide a pickup truck cover that has a high strength to thickness ratio as compared to prior art covers. A related object is to provide a cover that has sufficient thickness and strength throughout the cover so that bolts, screws, or other fasteners can pass through the cover to securely attach accessories to the cover at any location on the cover. 
   Yet another object is to provide a pickup truck cover that uniformly supports the top and bottom shells over numerous supporting points to minimize witness marks on the visible portion of the top shell and to facilitate painting or the use of molded in colors. 
   These and other objects and advantages will be apparent from the following description of the drawings and description of the preferred embodiment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a rear perspective view of an exemplary embodiment of a tonneau cover installed on the cargo bed of a pickup truck according to the invention. 
       FIG. 2  is a perspective view of an exemplary embodiment of a tonneau cover in the opened position according to the invention. 
       FIG. 3  is a rear perspective view of an exemplary embodiment of a tonneau cover with the cover in the opened position according to the invention. 
       FIG. 4  is a rear view of an exemplary embodiment of a tonneau cover with the cover in the opened position according to the invention. 
       FIG. 5  is a cross-sectional view of an exemplary embodiment of a tonneau cover according to the invention. 
       FIG. 6  is an enlarged cross-sectional view of an exemplary embodiment of a tonneau cover according to the invention. 
   

   DETAILED DESCRIPTION 
   Turning first to  FIG. 1 , an exemplary embodiment of the inventive tonneau cover  10  is illustrated in its closed position covering the cargo bed of a pickup truck. The cover  10  has a smooth top surface  12  and an underside surface  13 , with side overhanging edges  14 , and a rear overhanging edge  16 . Grain or texture can be formed into top surface  12  and top surface  12  can be formed with various surface geometries and patterns. For purposes of this patent “smooth outer surface” means a surface of a single sheet of plastic that has an attractive consistent finish (e.g., there are no visually significant witness lines or variations in color caused by the support structure) whether or not formed with various macro-geometries, shapes, and/or patterns (see, e.g.,  FIG. 1 ). The overhanging edges  14 ,  16  extend over upstanding walls  18  of the truck bed  20  so that water runs off the top  12  and does not enter into the cargo bed. The cover  10  is illustrated in the raised position in  FIGS. 2-4 . Gas charged or air cylinders  22  control the speed at which the cover  10  is raised and lowered. They can also assist in keeping the cover  10  in the raised position until the user desires to lower the cover  10  to cover the truck bed  20 . As seen clearly in  FIG. 3 , there is a strap  24  connected to the cover  10  to assist in pulling the cover  10  down to the closed position. The strap  24  is connected to the underside  13  of cover  10  with a fastener  26  passing completely through the cover  10  to securely fasten the strap  24  to the cover  10 . The tonneau cover is thus installed and functions similarly as the tonneau covers of the prior art. 
   The cover  10  can also be provided with gaskets  15  near the perimeter of the underside  13  of cover  10  in alignment with the top of the upstanding walls  18 . This keeps moisture and other foreign objects from entering the cargo bed when the cover  10  and gaskets  15  are closed on the upstanding walls  18 . The cover  10  can also be provided with a locking mechanism to limit access to the cargo bed when the cover  10  is closed and the lock engaged. 
   The structure of the cover  10  is illustrated in  FIGS. 5 and 6 . There is a top sheet  30  which has an outer surface  30   a  exposed to the elements and visible for observation at all times and an inner surface  30   b . For this reason top sheet  30  must be weather and ultraviolet resistant and be capable of maintaining an attractive painted or molded outer surface  30   a  even though exposed to the elements. Thus, top sheet  30  is generally made from a blend of polycarbonate (referred to as “PC”) and acrylonitrile butadiene styrene (referred to as “ABS”) plastic which has these qualities (the two polymers blended together is referred to herein as “PC/ABS”). In various embodiments, top sheet  30  may be made from materials such as polycarbonate acrylonitrile butadiene styrene, acrylonitrile butadiene styrene, fiber reinforced polyethylene, and/or fiber reinforced thermoplastic polyolefin. Alternatively it may have an acrylic or thermoplastic polyolefin (referred to as “TPO”) surface that is co-extruded over PC/ABS plastic which gives the outer surface  30   a  of top sheet  30  additional ultraviolet ray resistance and improved color characteristics. It may also have a paint film laminated or co-extruded over the top sheet  30 . 
   In another embodiment the top sheet may be manufactured from a fiber reinforced plastic sheet which may make it possible to use thinner plastic having the same qualities and characteristics. 
   Beneath the top sheet  30  is a first fiberglass layer  32 . This can be made with a fiberglass mat or a sprayed-in layer of chopped fiberglass. A ¾ ounce fiberglass mat is used in the preferred embodiment. The thickness of the first fiberglass layer  32  is approximately 0.015 inches. 
   Next there is a layer  34  of honeycomb structure. This is preferably a Kraft paper product fabricated to form a continuous series of triangular cells, similar in appearance to the cross section view of corrugated board. The honeycomb can be supplied by Tricel Honeycomb Corporation, 2100 Swanson Court, Gurnee, IL 60031 and sold under the trademark TRICEL. In other embodiments, the honeycomb may be made from materials such as paper, reinforced paper, cardboard, reinforced cardboard, plastic, and metal. The honeycomb cores are up to 95% open space, with a density of one to three pounds per cubic foot. The maximum distance between cell walls should not be greater than five inches in order to provide sufficient structural strength. When bonded to a facing material on both sides, the resulting structure resembles an I-beam in performance and carries substantial shear, bending and compressive loads. In an alternative embodiment the honeycomb structure can be fabricated from plastic, metal, or cardboard or otherwise reinforced for additional strength. The honeycomb layer  34  defines a plurality of edges or joining lines  46  on both sides of the honeycomb layer  34  that contact the layers immediately above and below the honeycomb layer. In various embodiments, the joining lines  46  are bonded to the first fiberglass layer  32  and/or the second fiberglass layer  36 . 
   The honeycomb  34  can be impregnated with phenolic resin for additional strength. The honeycomb is easier to bond to fiber reinforced plastics and other plastics than other closed cell products such as foam. The honeycomb  34  can be easily cut with a knife, band saw, or power saw. It is very cost effective when compared to other middle layer materials such as particleboard, foam, Balsa, or plywood. Beneath the honeycomb structure  34  is a second layer of fiberglass  36 . This is similar to the first layer  32  and preferably identical to the first layer  32 . Beneath the second layer  36  is a bottom sheet  38 . The bottom sheet  38  is similar to the top sheet  30  and generally made of PC/ABS plastic to impart additional strength and temperature performance. It has an outer surface  38   a  and an inner surface  38   b . Additionally, bottom sheet  38  has an up-rolled structure  39  near its perimeter for added stiffness. 
   In order to manufacture the completed tonneau cover  10 , the process is as follows. First the top sheet  30  is turned upside down exposing the inner surface  30   b . The outer surface  30   a  of the top sheet  30  is protected so that the outer surface  30   a  is not scratched. The inner surface  30   b  is sprayed with a polyester resin  48  such as Hycryl H515-BCA-08 polyester resin manufactured by AOC located at 950 Highway 57 East, Collierville, Tenn. 38071. Next the fiberglass material is applied. If a fiberglass mat is used, it is laid in on top of the polyester resin. If the fiberglass is sprayed on, it is applied in the recommended manner on top of the resin. This is followed by another application of the polyester resin  48 . The first fiberglass layer  32  will absorb some of the resin. The honeycomb structure  34  is placed on the fiberglass layer  32 . Another application of the polyester resin is applied to the honeycomb structure  34 . Then the second fiberglass layer  36  is laid in on top of the honeycomb structure  34 . This is followed by another application of the polyester resin  48  and/or by applying another adhesive to the inner surface  30   b  of the perimeter of top sheet  30 . Lastly the bottom sheet  38  is applied on top of the second fiberglass layer  36  on honeycomb structure  34  and the inner surface  30   b  of the top sheet  30 . The inner surface  38   b  comes in contact with the second fiberglass layer  36 . The up-rolled structure  39  in bottom sheet  38  provides additional surface for the perimeter adhesive  48 . The entire cover  10  is restrained in its final shape until the resin and/or other adhesive reach a handling cure. The restraint is then removed and the cover  10  is ready for any final trimming or decorating and assembly. 
   One improvement of this cover  10  over prior art covers is that the use of the honeycomb with fiberglass layers adds structural strength and temperature performance to the cover, and the resin greatly improves the bonding between the top sheet  30  and the honeycomb structure  34  and the honeycomb structure  34  and the bottom sheet  38 . The first fiberglass layer  32  and the second fiberglass layer  36  act as a binder to resist separation of the honeycomb structure  34  from the top sheet  30  and the bottom sheet  38 , especially in shear mode. This problem is very apparent when foam is used as a layer between plastic top and bottom sheets. 
   The center of cover  10  has a final cross sectional thickness ranging from approximately 0.625 to 1.125 inches thick, which is comparable to or less than other tonneau covers on the market, having similar strength qualities. The cover  10  also allows attachment of accessories to the cover over its entire surface as it is uniform in thickness and strength. For example the strap  24  is attached by the fastener  26  that passes through the cover  10  and can be located anywhere on the outer surface  38   a  of the bottom layer of cover  10 . This is a great improvement over prior art devices that only allowed attachment of accessories at specific reinforced locations over the surface of the cover. 
   In various embodiments, the top sheet is provided with a perimeter edge  40  in the form of a turned down lip. Bottom sheet  38  may be provided with a complementary perimeter edge  42  that is adapted to fit with and be joined to perimeter edge  40 . In various embodiments, the perimeter edge and the complementary perimeter edge  42  are joined with an adhesive. 
   Thus there has been provided a tonneau cover that fully satisfies the objects and advantages set forth herein. While the invention has been described in conjunction with a specific embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description such as using different shell geometries, different shell materials, different bonding agents, different bonding layers, different honeycomb geometries and different honeycomb materials. Accordingly, it is intended to embrace all such alternatives, modifications and variations.