BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to school bus seats and more particularly to an injection-molded riser for a modular school bus seat frame which provides a reduced weight, high strength, module. 
         [0003]    2. Description of the Problem 
         [0004]    School bus seats are built to meet many differing customer specifications. For example, some bus seats must accommodate three point safety belts by providing a compatible upper back rest, other specifications call for a universal child restraint attachment equipped lower frame, while still others provide standard DOT (United States Department of Transportation) seat backs. At the same time customers can specify seats in different widths or heights and can demand various strength requirements be met. 
         [0005]    Meeting such diverse specifications have required manufacturers stock substantially or entirely different component sets in order to produce seats. The need to supply such component sets has even occurred relative to completed vehicles that have been put into service where the vehicle has been moved from one state or municipality to another, based on differing requirements of the new jurisdiction. Modularity of the components, that is the ability to use one component to build seats meeting different functionality, can reduce the number of different components required to construct seats adapted to particular customer requirements. 
         [0006]    Modular construction of bus seat frames is known, one example being taught in U.S. Pat. No. 6,886,889 to Vits et al. FIGS. 18-20 of the Vits &#39;889 patent teach a modular seat based on four major sub-assemblies. The sub-assemblies include a frame assembly, a floor mount assembly, a passive restraint panel and a seat member. The floor mount assembly in turn comprises one or two pedestals on which frame elements for a seat bench rest. In some embodiments one of the pedestals is replaced by a wall mount bracket shown in FIGS. 26 and 27 of the patent. Vits does not describe fabrication of the pedestals at length. 
         [0007]    U.S. Pat. No. 7,303,235 to Fongers described a chair for mounting to a bleacher seat where the chair was an injection molded seat with strategically shaped and positioned strengthening ribs being inherent to the seat elements. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention provides a riser assembly for a modular seat assembly for school busses. The riser assembly includes a riser, a support neck reinforcement member for supporting a seat back frame from the riser, floor attachment members, localized reinforcement pieces and a front cross member attachment member. The riser is preferably molded from glass or talc filled polypropylene or nylon. The riser is molded with strengthening ridges disposed in an egg crate pattern, that is, a major face of the riser includes a plurality of strengthening ridges disposed in two mutually orthogonal sets. The riser is molded to conform with the attachment members and reinforcement pieces by providing slots into which some attachment members can be fitted. 
         [0009]    Additional effects, features and advantages will be apparent in the written description that follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    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: 
           [0011]      FIG. 1  is a perspective view of a school bus seat frame. 
           [0012]      FIG. 2  is an exploded view of a seat riser assembly for the school bus seat frame of  FIG. 1 . 
           [0013]      FIG. 3  is a detail view of molded features of the riser adapted to receive a representative attachment member. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    Referring now to the drawings and in particular to  FIG. 1 , an assembled modular school bus seat frame  40  is illustrated. Modular school bus frame  40  is installed upright on a bus floor  42 . Modular frame  40  is supported on its inside end from a chair rail  62  of a school bus interior wall  44  and along its opposed end adjacent a center aisle from the floor  42 . Support from the wall  44  is provided by a wall riser  48 . Support from the floor  42  is provided by an aisle riser assembly  46 . Aisle riser assembly  46  and wall riser  48  differ from the aisle risers and floor risers known from the art in that they form part of what would traditionally be considered the frame itself, and are not simply pedestals on which the seat frame is mounted. The aisle riser assembly  46  includes a support neck  50  which provides a base of support for an open, partial perimeter tube  52  used to define the top and sides of a seat back portion of frame  40 . The partial perimeter tube  52  is a C shaped element mounted at opposite ends in necks  50  which defines the top and sides of the seat back. Suspended on and within the partial perimeter tube  52  is a seat back panel  54 . Extending between and fitted into the aisle riser assembly  46  and the wall riser  48  are front and back latitudinal supports  60  and  56 . Supports  56  and  60  come in varying lengths to support seats of varying widths. Riser assembly  46  includes a riser which is molded and has an interior side (the side facing away from the aisle for a riser assembly installed adjacent the aisle or the side oriented toward the aisle for a riser installed adjacent a side wall of the vehicle) which is formed with a moderately dense egg crate pattern of intersecting reinforcing ribs to add structural strength to the riser. 
         [0015]      FIG. 2  illustrates the components of a riser assembly  46  featuring the interior side or major face  75  of riser  76 . The interior side  75  features particularly a plurality of horizontal ribs  78  and vertical ribs  80  which intersect and operate to strengthen the riser  76 . The sets of ribs  80  and  78  should be formed in the molding process to be substantially orthogonal, though it is not essential that they be vertical and horizontal. In addition, various attachment members and reinforcing plates are illustrated. These are provided at points of particular stress, such as the point of attachment of the riser  46  with the floor and the point of attachment of the seat back tube  52 . 
         [0016]    A neck member  50  includes a tube section  81  which mates with on end of tube  52  and a gusset  82  which may be joined with the main body of riser  76  by being fitted against the egg crate pattern of ribs  78 ,  80 . The tube section  81  of neck member  50  is sized to fit snugly within a riser extension  70  which is an open faced trough. Neck member may also be made of the same material as the riser  76 . 
         [0017]    A rear floor mounting member and reinforcement plate  74  reinforces the riser  76  at another point of stress, that is the point of attachment of riser  76  to the floor of a bus at the back of riser  76 . Rear floor mounting member  74  is an L shaped member which fits against an aft, downward extension of the riser  76 , which terminates in a foot  90 . Holes  93  through member  74  may be aligned with holes  95  through the foot  90  for the insertion of fasteners (not shown). Similarly a smaller mounting plate  72  is used with the front foot of the riser  76 . 
         [0018]    Riser  76  provides for the attachment of cross members to support a seat using attachment plates such as attachment plate  61 , which fits to the front portion of the riser. Plate  61  includes a right angle bend to accommodate a cross member which extends between the aisle riser assembly and a wall riser assembly. 
         [0019]    Referring to  FIG. 3 , an attachment member  118  for a seat frame member  150  is illustrated, as well as modifications made along an edge of riser  76  which provide for easy connection of the attachment member to the riser. Riser  76  incorporates an L shaped ridge  102  which in turn defines a slot  103 . A block  104  is formed in the riser  76  below the ridge  102 . Similarly a second ridge  121  is disposed below the block  104  defining a second slot  119 . Attachment member  118  is a C shaped bracket, preferably made of metal which includes tabs  116  and  117  at the ends of upper and lower “arms” of the C. Tabs  116 ,  117  mate with slots  103  and  119 , respectively, as part of attaching the member  118  to the riser  76 . A seat frame member  150 , which itself is shaped as a shallow C in cross section, fits snugly inside attachment member  118  and brackets block  104 . Holes  112  through attachment member  118  and holes  106  in block  104  may be aligned for the insertion of fasteners  110 . The use of fasteners avoids the use of welding which can thermally weaken components. 
         [0020]    While only a preferred embodiment is described here, the claims are not thus limited but is cover various changes and modifications to that embodiment without departing from the spirit and scope of the claims.
A modular seat frame for a school bus seat includes riser assemblies for supporting the seat fabricated from a moldable material reinforced locally by attachment and reinforcement members.