Abstract:
An improved trailer hitch housing is provided having a pair of integrated ribs extending the length of each side of the housing. The ribs strengthen and stiffen the housing by decreasing the tendency of the sides to bend when subjected to stress. The need for internal bracing or end flanges, which are used in prior art devices for strength and stiffness, is eliminated by the use of the ribs.

Description:
This application is a continuation of Ser. No. 08/217,744, filed Mar. 25, 1994, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to trailer hitches and, more particularly, to a trailer hitch housing independently supported by strengthening ribs provided along the sides of the housing. 
     Trailer hitch housings are well-known in the art. The housings are connected to trailers by means of bolts, weldments, or similar securement means. The housings are typically designed to cover and support socket assemblies, which are used to releasably attach the trailer to a hitch ball of a pulling vehicle. The housing must, therefore, be extremely strong to maintain its integrity as the trailer is being pulled. Although most housings are constructed of steel or a similarly rigid metal, they are not immune to damage from external forces. As housings are used, they are subjected to many forces which act to deflect or bend the housings. If housings were to succumb to such forces the housing would fail leading to potential injury to both persons and property. Accordingly, internal bracing or end-flanges are typically required to produce housings capable of withstanding these deflecting and bending forces. However, since internal bracing and end-flanges add weight and cost to the housings, it is desirable to provide a housing which is low cost and relatively lightweight. 
     Housings generally consist of a pair of sides and a cover secured to and mounted between the sides. Alternatively, the housing may be constructed of a single sheet of metal which is formed into a pair of sides and a cover. Several housings have been designed in an attempt to provide a relatively thin, lightweight housing with the strength required for towing a trailer. The two most popular designs are the end-flanged design and the internally braced design. 
     In the end-flanged design, a small portion of the bottom edges of the sides of the housing are turned outwardly to reduce the tendency of the sides to deflect or bend under pressure. While this design adds stability to the housing, the flanges detract from the aesthetic quality of the housing. Furthermore, the housing must still be constructed of a relatively thick material to withstand deflection between the end-flanges and the cover. The exposed flanges also have undesirable sharp corners which tend to catch and snag on nearby articles. 
     The internally supported design typically has internal braces or supports which extend between the sides of the housing and are secured thereto by weldments or bolts. As the internal braces must be relatively sturdy and placed throughout the housing, the internal support structure adds a significant amount of weight to the housing. The weldments or bolts making up the internal support structure are often visible on the exterior of the housing and, therefore, detract from the housing&#39;s aesthetic quality. Additionally, the placement of the braces within the housing requires a significant amount of additional labor, which adds a significant amount of time and cost to the manufacture of the housing. The braces also block much of the internal portion of the housing, thereby hindering the placement of surge suppressors, locks, or other apparatuses which may need to be placed within the housing. 
     The difficulties encountered in the prior art discussed hereinabove are substantially eliminated by the present invention. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a trailer hitch housing which resists deflection and bending, but is not significantly heavier than a trailer hitch housing having no buckling or twisting supports. 
     It is another object of the present invention to provide a trailer hitch housing with a strengthening member which does not add a significant increase in bulk to the housing. 
     Still another object of the present invention is to provide a trailer hitch housing having an aesthetically appealing appearance. 
     It is another object of the present invention to provide a trailer hitch housing which eliminates the need for an internal support structure. 
     By the present invention, it is proposed to overcome the difficulties encountered heretofore. To this end, a fully externally supported trailer hitch housing is provided capable of operably connecting a trailer to a pulling vehicle. The housing has a first side divided into a first lower plate and a first upper plate by a first strengthening rib. The first strengthening rib is capable of independently supporting and strengthening the first side of the housing as the trailer is being pulled by the vehicle. The housing also has a second side constructed similar to the first side having a second strengthening rib capable of independently supporting and strengthening the second side of the housing as the trailer is being pulled by the pulling vehicle. A housing cover is provided which is attached to and interconnects the first side and second side of the housing. Preferably, the lower plates are smaller than the upper plates and the strengthening rib is disposed across the entire length of the sides, to provide the greatest strength and durability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of a trailer housing provided with a strengthening rib according to the present invention; 
     FIG. 2 is a side elevational view of the trailer housing; 
     FIG. 3 is a top plan view of the trailer housing; 
     FIG. 4 is a perspective view of the trailer housing in partial cross-section taken along line  4 — 4  of FIG. 1; and 
     FIG. 5 is a cross-section of the trailer housing taken along line  5 — 5  of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention relates to a trailer hitch housing  10  being provided with a first rib  12  and a second rib  14 , which strengthen and support the housing  10  to counter buckling, bending, and twisting forces to which the housing  10  is subjected (FIG.  4 ). 
     In the figures, a trailer hitch housing  10  is shown having a first side  16  and a second side  18  (FIG.  1 ). The sides  16  and  18  are preferably constructed of steel to give the housing  10  added  10  durability and strength. Interconnecting the sides  16  and  18  is a housing cover  20  which is also preferably constructed of steel (FIGS.  1  and  3 ). Although the housing cover  20  may be welded to the sides  16  and  18 , it is preferable to construct the housing  10  of a single sheet of steel, bent at a first corner  22  and a second corner  24  to form the two sides  16  and  18 , the cover  20 , and a front  26  and a back  28 . 
     The ribs  12  and  14  are formed in the sides  16  and  18  by cold working or similar metal working means (FIG.  5 ). Cold working is the preferred method of forming the ribs  12  and  14  as it provides the ribs  12  and  14  with the strength needed to withstand the forces to which the housing  10  is subjected. Preferably the cold working is done in a manner which allows the width of the steel forming the ribs  12  and  14  to be of substantially the same width as the sides  16  and  18 , and which provides the ribs  12  and  14  with a front  30  and a rear  32  (FIGS.  2  and  5 ). The ribs  12  and  14  are preferably formed to provide crests  34  having arcuate cross-sections, rather than pointed cross-sections, to reduce the chance of the housing  10  folding along the ribs  12  and  14  when subjected to external forces (FIG.  5 ). Preferably, the ribs  12  and  14  are provided parallel to the housing cover  20 , within one centimeter from the front  26  and one centimeter from the rear  28  of the housing  10  (FIGS.  1  and  4 ). The front  30  and a rear  32  of the ribs  12  and  14  are preferably rounded to eliminate any sharp angles which may snag or damage articles contacting the ribs  12  and  14 . By eliminating the internal support structure present in most prior art housings, the ribs  12  and  14  decrease the weight and bulk of the housing  10 , opening up the interior of the housing  10  for placement of surge suppressors (not shown) or other devices. The ribs  12  and  14  also add attractive aesthetics to the housing  10 . 
     The rib  12  is preferably positioned to divide the side  16  into a larger, upper portion  36  and a smaller lower portion  38  (FIG.  4 ). This positioning of the rib  12  provides maximum support to the housing  10 , as the larger, upper portion  36  is strengthened and supported by both the housing cover  20  and the rib  12 , while the smaller, lower portion  38 , needing less strength and support due to its smaller surface area, is supported only by the rib  12 . The rib  14  is preferably positioned at an identical orientation on the opposite side  18  to provide similar benefits. 
     The increase in strength afforded by the ribs  12  and  14  is directly related to the resistance of the sides  16  and  18  to deflection. For a flat plate the equation for deflection is:        Y   =       F                   l   3         3      E                 I                              
     wherein Y is the deflection in inches, F is the force on the plate,  1  is the length of the plate, E is the modulus of elasticity of the material, and I is the moment of inertia. The equation for the moment of inertia is given as follows:        I   =       b                   h   3       12                            
     wherein b is the length of the plate and h is the height of the plate. Accordingly, compared to a flat plate of an identical length, a ribbed plate has a greater height and, therefore, a greater moment of inertia. 
     Adding the ribs  12  and  14  to the sides  16  and  18  of the housing  10  increases the moment of inertia of the sides  16  and  18 , thereby decreasing the deflection and increasing the strength of the sides  16  and  18  as well. The increased strength provided by the ribs  12  and  14  is sufficient to eliminate the need for internal bracing or end flanges. 
     The foregoing description and drawings merely explain and illustrate the invention and the invention is not limited thereto, except insofar as the claims are so limited, as those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention. By way of example, it should be clear that the ribs  12  and  14  may be inverted so that the crests  34  of the ribs  12  and  14  are on the interior rather than the exterior of the housing  10 . By way of further example, it should be clear that numerous ribs of varying length may be provided over the sides  16  and  18  of the housing.