Abstract:
A body structure for a customized van is enhanced by providing a roof support element which is light in weight, strong, and easily shaped to conform to curved roof lines. The body structure comprises a rafter having upper and lower extruded rails and a plurality of gussets connected between the rails to join the rails in a single member. The rails are T-shaped in cross section with the upright of the T providing a point for connection of the gussets.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The invention relates generally to trailers, recreational vehicles, and custom van body structures and, in particular, to a roof support of light weight and possessing ease of fabrication which supports vehicle roofs of contoured shapes of variable radii. 
   2. Description of the Problem 
   Recreational vehicles and vacation trailers make frequent use of a raised roof, which allows the addition of ceiling mounted entertainment equipment and storage space, and the routing of air ducts. Fabrication of an aesthetically pleasing roof fit for these purposes, which also exhibits strength, is better served by providing designers the ability to incorporate curved sheet metal elements, rubber membranes, or fiber glass sections, rather than flat elements. Underside supports for such roofs should conform to the shape of the roof if possible. These supports should also limit or reduce the direct labor cost involved in construction of the vehicle. 
   Contemporary design has relied on square cross section extruded aluminum channels as structural elements. The channels are often joined using galvanized steel sheet metal gussets to fabricate roof support elements. Fabrication of roof support elements from these elements has required welding, adhesive joining or screws, adding greatly to direct labor required to construct the vehicles. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided a rafter for supporting the roof of vehicle. The rafter comprises lower and upper rails of sufficient length to extend from side to side of a roof of a vehicle. The lower and the upper rail each have a cross member and an upright member extending outwardly perpendicular from one face of the cross member. The upper and lower rails are disposed in a common plane with their respective upright members extending toward one another. A plurality of gussets are attached to the upright members and extend between the lower and upper rails to join the upper and lower rails to one another. The upper rail is shaped to allow a face of the cross member to fit against an underside surface of the roof of a vehicle. The rafter further includes the lower rail having an elongated pocket defined between one side of the upright member and a side of the cross member to one side of the upright member. 
   Additional effects, features and advantages will be apparent in the written description that follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIGS. 1A and 1B  are perspective views of recreational vehicles. 
       FIG. 2  is a front elevation of a roof support element or rafter and supported vehicle roof. 
       FIG. 3A  is an enlarged front elevation of the rafter of  FIG. 2 . 
       FIG. 3B  is a front elevation of an alternative embodiment for the rafter of the invention. 
       FIG. 4  is a perspective view of a section of an elongated member adaptable to serve as a chord or base member of the rafter. 
       FIGS. 5A–B  are views of a gusset used with the chord and elongated base members. 
       FIG. 6  is a detail view of one end of the rafter. 
       FIG. 7  is an end of view of the rafter. 
       FIG. 8  is a perspective view of a section of an alternative elongated member adaptable to serve as a chord or base member of the rafter. 
       FIGS. 9A–B  are views of a gusset used with the alternative elongated base members. 
       FIG. 10  is an end view of the alternative elongated base member. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the figures and in particular to  FIGS. 1A–B  there are illustrated recreational vehicles  10 ,  11  having roofs  12 ,  13 . Roofs  12 ,  13  may be advantageously supported by the rafters disclosed by the present patent. 
   Referring to  FIG. 2 , the disposition of a roof support member or rafter  14  in relation to the underside  16  of vehicle replacement roof  12  or roof  13  is shown. Roof  12 , and its underside  16 , follow a gentle curve and are higher down the longitudinal center line of the roof than along the right and left hand sides of the vehicle. Rafter  14  supports roof  12  from side to side of the roof, the rafter conforming along the length of its upper surface to the side to side curvature of roof  12 . Rafter  14  comprises an curved upper rail or chord  30  and an elongated base member  32 , both of which are extruded aluminum members or rails. The radius of curvature of chord  30  may be varied to conform to the desired shape of replacement roof  12 . Chord  30  and elongated base member  32  are disposed with the chord positioned above and aligned with the elongated base member in a common plane. Chord  30  and elongated base member  32  are joined to one another using a plurality of gussets including gussets  22 A and  23 A. Gussets  22 A and  23 A are disposed with respect to one another and include right angle notches  24  along one edge of each of the gussets to define a frame  20  through which ventilation ducts  18  may be passed. 
   Referring now to  FIG. 3A , the construction of rafter  14  is illustrated in greater detail. Chord  30  and elongated base member  32  are elongated rails disposed roughly parallel to one another discounting the curvature of chord  30 . The curvilinear shape of chord  30  brings the ends of the chord closer to the ends of base member  32  than is the center of the chord relative to the center of the elongated base member and gives upper face  72  of rafter  14  a convex shape. Base member  32  and chord  30  incorporate flange like central upright members  64  (see  FIG. 4 ) which extend toward one another and stiffen the rails longitudinally. The plurality of gussets are attached at bottom and top to central upright members  64 . The gussets are identified by position in the preferred rafter  14  illustrated. At each end of rafter  14  is a rectangular end gusset  38 . Moving inwardly from the ends are rhomboid shaped gussets  36 A and  36 B which are disposed to cant inwardly from bottom to top. Still further inwardly are a second set of rhomboid gussets  34 A and  34 B, which are canted outwardly from bottom to top. Still further inward toward the longitudinal center line of the vehicle are rhomboid gussets  22 A and  22 B. Rhomboid gussets  22 A and  22 B and  28 A and  28 B are all canted toward the center line of the vehicle from bottom to top. Rhomboid gussets  22 A and  22 B include a right angle notch on an inboard edge. Rhomboid gussets  23 A and  23 B, which are the next gussets inward from gussets  22 A and  22 B, are outwardly canted from bottom to top and also incorporate right angle notches  24 , this time along an outwardly oriented edge so that the notches define two frames  20  through a rafter  14 . Disposed along the vehicle center line and at the center of rafter  14  is a rectangular gusset  26 . 
   Referring now to  FIG. 3B  the construction of an alternative embodiment rafter  114  is illustrated. Again the chord  30  and elongated base member  32  are elongated rails disposed roughly parallel to one another discounting the curvature of chord  30 . The curvilinear shape of chord  30  brings the ends of the chord closer to the ends of base member  32  than is the center of the chord relative to the center of the elongated base member and gives upper face  72  of rafter  114  a convex or outwardly bowed shape. Base member  32  and chord  30  incorporate flange like central upright members  64  (similar to those illustrated in  FIG. 4 ) which extend toward one another and stiffen the rails longitudinally. Instead of gussets, aluminum sheets are attached at bottom and top to central upright members  64  of chords  30  and  32 . A single aluminum sheet may be used, as indicated by sheet  126  which spans a frame  120  through the sheet, or the sheet may be broken into segments, as indicated by the break between sheet  122  and sheet  126  occurring at frame  220 . 
   Referring to  FIG. 4  a representative elongated rail  60 , which may serve as either chord  30  or elongated base member  32 , is illustrated to advantage in perspective. Elongated rail  60  has a T-shaped cross section with a cross member or bar  62  and an upright member  64  which extends outwardly from one face of the cross bar  62 . At the juncture between upright member  64  and cross bar  62  a semi-cylindrical pocket  68  is formed which extends the length of rail  60  along one side of upright member  64 . Pocket  68  is formed by an indentation  66  in the base of upright member  64  and a raised lip  69  extending upwardly from cross bar  64 . Pocket  68  is accessible through a gap  71  (see  FIG. 7 ) between lip  69  and upright member  64 . Four parallel grooves  70  are formed into face  72  of cross bar  62  opposite the face upright member  64  joins the cross bar. Grooves  70  extend parallel to pocket  68  for the length of rail  60 . As stated above, rail  60  is extruded from aluminum and can given a curved shape to conform to the shape of a replacement roof. Pocket  68  provides a position for placement of a gusset edge or aluminum sheet edge. 
     FIGS. 5A–B  illustrate end gusset  38 , which is taken as representative of the gussets or aluminum sheets generally. Gusset  25  has four edges one of which, intended for introduction to a pocket  68 , is shaped as a hook  40  which is rounded on one side to nestle into pocket  68  under the main body of upright member  64  and indented on the opposite side to cooperate with lip  69 . Hook edge  40  is intended to be fitted into the a pocket  68  in the usually straight, elongated base member  32 . 
   Referring to  FIGS. 6 and 7  views of an end portion of rafter  14  illustrate cooperation between a representative gusset, here end gusset  38 . End gusset  38  connects chord  30  with elongated base member  32  by attachment to upright members  64 , which extend toward one another from their respective rails. Attachment is by means of conventional fasteners  80  driven or screwed through the gusset  38  and adjacent upright member  64 . Hook edge  40  of gusset  38  is positioned downwardly, disposed in pocket  68  of elongated base member  32 . The opposite edge of gusset  38  may, at one end closer to the end of rafter  14 , be placed in a pocket of chord  30 , if provided. The bulk of the loading of gusset  38  is however carried through fasteners  80  whether gussets or an aluminum sheet is used. 
   In some embodiments the semi-cylindrical pocket  68  may be eliminated. Referring to  FIG. 8  a representative elongated rail  160 , which may serve as either chord  30  or elongated base member  32 , is illustrated. Elongated rail  160  has a T-shaped cross section with a cross member or bar  162  and an upright member  164  which extends outwardly from one face of the cross bar  162 . At the juncture between upright member  164  and cross bar  162  a base platform  168  is formed which extends the length of elongated rail  160  along one side of upright member  164 . Base  168  is formed by a raised section at the base, or point of juncture of upright member  164 . Four parallel grooves  170  are formed into face  172  of cross bar  162  opposite the face upright member  164  joins the cross bar. Grooves  170  extend parallel platform  168  for the length of elongated rail  160 . Rail  160  is extruded from aluminum and can given a curved shape to conform to the shape of a replacement roof. Platform  168  provides a position for placement of a gusset or aluminum sheet edge. 
     FIGS. 9A–B  illustrate end gusset  138 , which is taken as representative of the gussets or aluminum sheets generally. Gusset  138  has four straight flat edges, anyone of which may abut a platform  169  for support. 
   Referring to  FIG. 10 , an end portion of rafter  14  illustrate cooperation between a representative gusset, here gusset  138  and a T-section aluminum rail  160  functioning as a chord. Edge  140  of gusset  138  is downwardly oriented, resting on platform  169  of elongated rail  160 . The bulk of the loading of gusset  138  is imposed on fasteners  80  as illustrated in  FIG. 6 . 
   The invention provides a rafter of light weight, strong, and easily shaped to conform to curved roof lines. The rafter is also simple, facilitating its manufacture with reduced direct labor input. 
   While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.