BACKGROUND ART Decorative wooden fences, particularly lattice-type fences, while attractive and very traditional, require frequent painting or staining and are susceptible to rot and insect damage. Injection molded plastic lattice has become widely accepted as a maintenance free alternative to wood lattice, however, plastic lattice is frequently used with traditional wooden posts, fence rails and moldings.

DISCLOSURE OF INVENTION Accordingly, the present invention is directed to a plastic fence assembly for installation between a pair spaced apart vertically oriented fence posts and associated method of assembly. The fence assembly includes a pair of upper and lower plastic fence rails, each having a length substantially equal to the distance between spaced apart fence posts. The upper rail having a downwardly faced U- shaped channel and the lower rail having an upwardly faced U-shaped channel integrally formed therein. A molded plastic fence panel is provided which is sized to span between the fence post and the upper and lower rails, the fence panel having an outer peripheral edge which is sized to fit within the U-shaped channels of the upper and lower rails and a pair of outboard vertical edges adjacent the fence posts.

A pair of plastic fence post connectors which are removably attachable to the fence posts are configured to support the ends of the upper and lower rails and the outboard vertical edge of the fence panel. Wherein the upper and lower rails, fence panel and the fence post connectors can be sub-assembled in a horizontal manner

positioned between the fence posts and pivoted up into the vertical plane of the post and attached thereto to form a completed and secure fence assembly. Preferably, the fence posts are likewise formed of plastic from two elongate channel members attached to one another in a clam shell manner forming a rigid elongate structure with an axial cross-section having an enclosed interior and a continuous outer peripheral surface.

BRIEF DESCRIPTION OF DRAWINGS FIGURE 1 is a perspective view of the completed plastic fence assembly installed on a pair of spaced apart vertically oriented fence posts; FIGURE 2 is an exploded view of the completed plastic fence assembly of Figure 1; FIGURE 3 is an end view of a plastic upper rail; FIGURE 4 is a cross-sectional side elevation taken along line 4-4 of Figure 3; FIGURE 5a is an end view of an adapter strip shown in Figure 2; FIGURE 5b is an alternative adapter strip configuration; FIGURE 5c is yet another alternative adapter strip configuration; FIGURE 6 is a cross-sectional side elevational view illustrating the orientation of the upper frame rail, the adapter strip and the fence panel; FIGURES 7 and 8 are back and front side elevational views of the post connector;

FIGURE 9 is a perspective view of a section of a post connector adapter strips used in alternative embodiment; FIGURE 10 is a partial cutaway side elevational view of a fence post; FIGURE 11 is an exploded view of the two sections used to make the fence post of Figure 10; FIGURE 12 is a perspective view of an alternative embodiment of the plastic fence assembly; FIGURE 13 is a perspective view of a decorative plastic collar used on the fence assembly embodiment of Figure 12; and FIGURE 14 is a perspective view of a hinged post connector of the type utilized in the Figure 12 embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of plastic fence assembly 20 illustrated in Figure 1 is installed between a pair of spaced apart vertically oriented plastic fence posts 22 and 24. Plastic fence assembly 20 is made up of an upper and lower plastic rail 26 and 28; a molded plastic fence panel 30 and a pair of plastic fence post connectors 32 and 34. Plastic fence assembly 20 is illustrated in exploded perspective view of Figure 2. Upper rail 26 and lower rail 28 each have a length which is substantially equal to a but slightly less than the distance between the distance between fence post 22 and 24. Each rail, 26 and 28, is provided with a U- shaped channel, 36 and 38, respectively, for receiving an upper and lower edge of the plastic fence panel 30. Since fence panels come in a variety of thicknesses, preferably U-shaped channels, 36 and 38, are sufficiently large to accommodate the thickest fence panel. When thinner fence panels are utilized, a pair of upper and lower adapter strips 40 and 42 are provided, having U-shaped channels formed therein sized to receive the desired thickness of the fence panel. Adapter strips 40

and 42 are preferably s-shaped in cross-section and design to axially slide into U- shaped channels 36 and 38 and the upper and lower rails 26 and 28. U-shaped channels 36 and 38 have a sufficiently narrow opening to prevent the alignment strip 40 and 42 from being withdrawn from in a direction normal to the horizontal axis of rails 26 and 28.

Post connectors 32 and 34 are each removably attachable to fence post 22 and 24 utilizing conventional fasteners such as screws, bolts and the like. Each of the plastic fence post connectors 32 and 34 are configured to support an end of the upper rail 26 and an end of the lower rail 28 and the outboard vertical edge of the fence panel 30. Each of the fence post connectors is provided with a mounting surface adapted to cooperate with the fence post and a pair of elongated spaced apart flanges which define an upper and lower socket 44 and 46, sized to receive an end of the upper and lower rail and a channel 48 extending therebetween sized to receive a vertical outboard edge of fence panel 30. In the embodiment illustrated in Figures 1 and 2, the fence post connectors 32 and 34 are unitary plastic molded members further illustrated in the perspective view. Side elevational views of the front and back of fence post connector 32 are provided in Figures 7 and 8 further illustrating sockets 44,46 and channel 48.

Upper and lower rails 26 and 28 preferably have a cross-section of the general configuration shown in Figure 3 which includes a closed section beam portion 50 and a pair of flanges 52 and 54 which define a generally U-shaped channel 36 therebetween. In the preferred embodiment illustrated, upper rail 26 is made up of two injection molded plastic sections which are bonded together about a vertical part line. One of the plastic sections is shown in side elevational view in Figure 4. Preferably, closed section beam portion 50 is provided with a number of interior ribs which further add to the structural rigidity of the assembled rail.

As illustrated in Figure 3, the U-shaped channel 36 formed between flanges 52 and 54, has an opening slightly narrower than its internal maximum dimension in order to axially receive adapter strip 40 which has a tu-shaped cross- section. Adapter strip 40 is illustrated in Figure 5a. Adapter strip 40 has an

enlarged head 56 and a medium width slot 58 formed therein for receiving the upper marginal edge fence panel 30. Figure 5b illustrates an alternative adapter strip embodiment 60 with a similar dimension head 62 to go with a narrower slot 64 in order to securely support the relatively thin fence panel. Yet another adapter strip embodiment is illustrated in Figure 5c and has a narrow slot 68 and wide slot 70 enabling the adapter strip to accommodate two thickness plastic fence panels by simply inverting the adapter strip. The orientation of adapter strip 40 relative to fence panel 30 and rail 26 are shown in the Figure 6 cross-section. It should be further appreciated that when a very wide fence panel is utilized, adapter strips would not be necessary. Similarly, rails 26 and 28 can be made with a relatively narrow U-shaped slot in order to engage a typical plastic fence panel directly without a use of adapter strips.

Post connectors 32 and 34 in the preferred embodiment illustrated in Figures 1 and 2, directly engage the upward marginal edges of fence panel 30.

Alternatively, channel 48 formed between the pair of flanges in the post connector 32, can be made relatively wide and a post adapter strip 72 illustrated in Figure 9, can be installed within the slot to accommodate specific fence panel thicknesses.

Plastic fence post 22 is illustrated in partial cutaway cross-sectional view in Figure 10. Plastic fence post 22 is shown mounted on a steel anchor post 72 which is set in a concrete footing 74. In applications where a significant load will be placed upon fence, fence post 22 is preferably mounted on a steel anchor post 72.

In high load situations, the steel anchor post would be held in a concrete footing74.

In low load situations, the fence post may be simply placed in a post hole dug in the earth.

Fence post 22 is preferably made up a pair of plastic channel sections 78a and 78b as illustrated in exploded view of Figure 11. These sections are injection molded and are provided with a series of elongate marginal edges and a number of transverse ribs 76a and 78b. These two sections are oriented in a clam shell manner illustrated in Figure 3 and bonded together by a weld or an adhesive.

In the preferred embodiment, these marginal edges are welded together using a

vibration welding technique. As illustrated in Figures 10 and 11, a pair of ribs 76a and 76b adjacent the lower end of the post define a pair of axially spaced apart apertures sized to receive anchor post 72. These ribs also significantly add to the structural integrity of the post 22.

Fence posts 22 and 24 like the other components utilized to manufacture the fence assembly, are preferably molded in thermoplastic material using an injection molding process. However, fence components could alternatively be molded using a thermoset material such as a bulk molding compound. The preferred embodiments illustrated were manufactured from injection molded polypropylene. The polypropylene used included a foaming agent resulting in a 0 to 20% foam content. Of course, a variety of other thermoplastic materials can be used such as high density polyethylene or the like.

When assembling fence assembly 20, the vertical fence posts are first installed at a preselected spaced apart distance, plastic upper and lower rails 26 and 28 are provided having a length which is slightly less than the spacing between the posts. The rails are cut as necessary to achieve the correct length. Molded plastic fence panel 30 is likewise provided having a length substantially equal to that of the upper and lower rails 26 and 28. The upper and lower rails 26 and 28 are placed on the upper and lower marginal edges of the fence panel 30 with the upper and lower peripheral edges of the fence oriented within the U-shaped channels in the upper and lower rails. A pair of plastic fence post connectors 32 and 34 are then positioned on the ends of the upper and lower rails with the ends of the upper and lower rails and the outboard marginal edge of the fence panel 30 sliding within the sockets 44 and 46 and channel 48 formed by the post connector flanges. With the post connectors 32 and 34 in place, the subassembly is completed. For ease of assembly, the subassembly is put together on the ground with the fence panel horizontal. Once a subassembly is completed, the lower end of the subassembly is placed between the fence posts and the plastic fence post connectors are attached to the fence post by a single screw on each side. The subassembly can then be pivoted up into the vertical orientation and the remaining screws connecting the post connectors to the fence post are installed thereby securely retaining components of the fence assembly in place.

An alternative embodiment of the fence assembly 80 is illustrated in Figures 12-14. The difference between fence assembly 20 and fence assembly 80 in Figure 12 is the structure of plastic fence post connectors 82 and 84 and the presence of decorative collars 86. A decorative collar 86 and plastic fence post connector 82 are shown in enlarged view in Figures 13 and 14, respectively. Fence post connector 82 is made up of a pair of elongate sections 88 and 90 which are hinged together at the bottom end 92. Each of the elongate sections 88 and 90 are provided with a flange 94 and 96 which collectively define an upper and lower sockets and a narrow channel for receiving the ends of the upper and lower fence rails 26 and 28, and the outboard marginal edge of the fence panel. Elongate section 90 is intended to be affixed to the fence post initially with the elongate section 88 hinged outwardly to a generally horizontal position as shown in Figure 12. The upper and lower rails 26 and 28, and the fence panel 30 are then positioned on the outwardly extending elongate section 88. The subassembly is then pivoted upward into a vertical orientation and elongate section 88 is secured in place by screws at its upper ends. Ideally, the central span of elongate section 88 is retained to a corresponding portion of elongate section 90 by snap fasteners or the like so that the screws are not exposed. In order to further hide exposed fasteners, decorative collars 86 which are initially positioned on the upper and lower rails inboard of their ends as shown in Figure 12 are slid outboard until the collars engage posts 22 and 24 and overly the ends of the post connectors hiding the fasteners joining the post connectors 82 to the vertical fence posts 22 and 24.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.