Patent Publication Number: US-6904848-B2

Title: Roof assembly and airflow management system for a temperature controlled railway car

Description:
RELATED APPLICATION 
     This application is a Divisional of U.S. patent application Ser. No. 10/071,173 filed Feb. 8, 2002, now U.S. Pat. No. 6,722,287 and claims the benefit of Provisional Application No. 60/267,882 filed Feb. 9, 2001; and which is related to U.S. patent application Ser. No. 10/071,165, filed Feb. 8, 2002, Abandoned; U.S. patent application Ser. No. 10/071,168 filed Feb. 8, 2002, now U.S. Pat. No. 6,575,102; and U.S. patent application Ser. No. 10/071,513 filed Feb. 8, 2002, now U.S. Pat. No. 6,892,433 which claim priority from the same provisional application. 
    
    
     TECHNICAL FIELD 
     The present invention is related to a railway car having a composite box structure mounted on a railway car underframe and more particularly to a roof assembly and airflow management system for a temperature controlled railway car. 
     BACKGROUND OF THE INVENTION 
     Over the years, general purpose railway box cars have progressed from relatively simple wooden structures mounted on flat cars to more elaborate arrangements including insulated walls and custom designed refrigeration equipment. Various types of insulated box cars are presently manufactured and used. A typical insulated box car includes an enclosed structure mounted on a railway car underframe. The enclosed structure generally includes a floor assembly, a pair of side walls, a pair of end walls and a roof. The side walls, end walls and roof often have an outer shell, one or more layers of insulation and interior paneling. 
     The outer shell of many railway box cars often has an exterior surface formed from various types of metal such as steel or aluminum. The interior paneling is often formed from wood and/or metal as desired for the specific application. For some applications the interior paneling has been formed from fiber reinforced plastic (FRP). Various types of sliding doors including plug type doors are generally provided on each side of conventional box cars for loading and unloading freight. Conventional box cars may be assembled from various pieces of wood, steel and/or sheets of composite materials such as fiberglass reinforced plastic. Significant amounts of raw material, labor and time are often required to complete the manufacture and assembly of conventional box cars. 
     The underframe for many box cars include a center sill with a pair of end sills and a pair of side sills arranged in a generally rectangular configuration corresponding approximately with dimensions for the floor of the box car. Cross bearers are provided to establish desired rigidity and strength for transmission of vertical loads to the associated side sills which in turn transmit the vertical loads to the associated body bolsters and for distributing horizontal end loads on the center sill to other portions of the underframe. Cross bearers and cross ties cooperate with each other to support a plurality of longitudinal stringers. The longitudinal stringers are often provided on each side of the center sill to support the floor of a box car. Examples of such railway car underframes are shown in U.S. Pat. Nos. 2,783,718 and 3,266,441. 
     Traditionally, refrigerated box cars often have less inside height than desired for many types of lading and a relatively short interior length. Heat transfer rates for conventional insulated box cars and refrigerated box cars are often much greater than desired. Therefore, refrigeration systems associated with such box cars must be relatively large to maintain desired temperatures while shipping perishable lading. 
     Ballistic resistant fabrics such as Bulitex scuff and wall liners are currently used to form liners for highway truck trailers. 
     A wide variety of composite materials have been used to form railway cars and particular box cars. U.S. Pat. No. 6,092,472 entitled “Composite Box Structure For A Railway Car” and U.S. Pat. No. 6,138,580 entitled “Temperature Controlled Composite Box car” show some examples. One example of a composite roof for a railway car is shown in U.S. Pat. No. 5,988,074 entitled “Composite Roof for a Railway Car”. 
     SUMMARY OF THE INVENTION 
     In accordance with teachings of the present invention, disadvantages and problems associated with insulated box cars, refrigerated box cars and other types of temperature controlled railway cars have been substantially reduced or eliminated. One embodiment of the present invention includes a roof assembly and an airflow management system satisfactory for use with a refrigerated box car or a temperature controlled railway car. 
     A roof assembly and airflow management system formed in accordance with teachings of the present invention provides a railway car with enhanced insulation, increased load carrying capacity, better temperature regulation, increased service life, and reduced maintenance costs as compared to a typical refrigerated box car. The roof assembly may be formed from vacuum molded, single pour, one piece, FRP panels or sheets. Various types of insulating materials and insulating foams may be encapsulated between two FRP panels or sheets. Vacuum infusion techniques may also be used to form portions of the roof assembly. Alternatively, a roof assembly may be formed from one or more pultrusions. Void spaces associated with such pultrusions are preferably filled with insulating foam. 
     Technical benefits of the present invention include flexible joints or flexible connections provided between a roof assembly and associated side wall assemblies and the end assemblies to allow expansion and contraction of these components in response to temperature changes while maintaining desired structural integrity of an associated composite box structure. 
     One aspect of the present invention includes an airflow management system defined in part by an air plenum attached to and extending from an interior surface of a roof assembly. The air plenum may direct air from a temperature control unit to selected portions of a composite box structure. The temperature control unit may be mounted on one of the end wall assemblies of the composite box structure. An interior bulkhead may be formed within the composite box structure adjacent to and spaced from the one end wall assembly to provide portions of an airflow path to return air to the temperature control unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following written description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1A  is a schematic drawing in elevation showing a side view of a temperature controlled railway car having a roof assembly and an airflow management system incorporating teachings of the present invention; 
         FIG. 1B  is an end view of the temperature controlled railway car of  FIG. 1A ; 
         FIG. 2  is a schematic drawing in section with portions broken away of a side wall assembly taken along line  2 — 2  of  FIG. 1A ; 
         FIG. 3  is a schematic drawing in section with portions broken away taken a long lines  3 — 3  of  FIG. 1B  showing interior portions of a composite box structure formed in accordance incorporating teachings of the present invention; 
         FIG. 4  is a schematic drawing in section with portions broken away showing selected features of a roof assembly, end wall assemblies and a floor assembly forming a composite box structure in accordance with teachings of the present invention; 
         FIG. 5  is a schematic drawing in section with portions broken away taken along lines  5 — 5  of  FIG. 3  showing portions of an airflow management system formed within a composite box structure incorporating teachings of the present invention; 
         FIG. 6  is a schematic drawing showing an isometric view with portions broken away of a composite box structure having an airflow management system formed in accordance with teachings of the present invention; 
         FIG. 7A  is a schematic drawing showing an isometric view with portions broken away of an air plenum assembly incorporating teachings of the present invention; 
         FIG. 7B  is a schematic drawing in section with portions broken away showing one end of an air plenum assembly coupled with airflow paths formed on an interior surface of an adjacent end wall assembly; 
         FIG. 8  is a schematic drawing showing an isometric view with portions broken away of two plenum panels coupled with each other in accordance with teachings of the present invention; 
         FIG. 9  is a schematic drawing, in section and in elevation with portions broken away, showing a hanger assembly formed in accordance with teachings of the present invention for attaching a plenum panel with a roof assembly; 
         FIG. 10  is a schematic drawing in section with portions broken away showing a typical flexible joint or flexible connection formed between a roof assembly and a side wall assembly in accordance with teachings of the present invention; 
         FIG. 11  is a schematic drawing showing an isometric view with portions broken away of trim molding satisfactory for use in forming portions of a flexible joint or flexible connection between a roof assembly and a side wall assembly in accordance with teachings of the present invention; and 
         FIG. 12  is a schematic drawing in section with portions broken away showing portions of an airflow path formed between an interior bulkhead and an end wall assembly incorporating teachings of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the invention and its advantages are best understood by reference to  FIGS. 1A-12  of the drawings, like numerals are used for like and corresponding parts of the various drawings. 
     Various aspects of the present invention will be described with respect to a roof assembly which may be formed at least in part by vacuum infusion techniques. Portions of the roof assembly may be formed from vacuum molded, single pour, one piece FRP panels or sheets. However, teachings of the present invention may be satisfactorily used to form a roof assembly and/or an airflow management system using various techniques including injection molding, extrusion and/or pultrusion technologies. Teachings of the present invention are not limited to techniques and materials described in this application to form a roof assembly and an airflow management system. 
     U.S. Pat. No. 4,404,057 entitled “Reinforced Plastic Sheet Machine and Methods” and U.S. Pat. No. 6,251,185 entitled “System for Delivering Chopped Fiberglass Strands to a Preformed Screen” describe various examples of equipment and procedures which may be used to form all or portions of a roof assembly and/or an airflow management system incorporating teachings of the present invention. Roof assembly  40 , which will be described later in more detail, may be purchased from Molded Fiberglass Companies located in Ashtabula, Ohio. 
     Temperature controlled railway car  20  incorporating teachings of the present invention is shown in  FIGS. 1A and 1B  with composite box structure  30  mounted on railway car underframe  200 . Portions of composite box structure  30  and railway car underframe  200  are also shown in  FIGS. 2-6 . Temperature controlled railway car  20  preferably includes a roof assembly and an airflow management system formed in accordance with teachings of the present invention. 
     For some application, temperature controlled railway car  20  may have exterior dimensions which satisfy requirements of Plate F and associated structural design requirements of the Association of American Railroads (AAR). Forming various components of composite box structure  30  in accordance with teachings of the present inventions and assembling these components on railway car underframe  200  results in reducing the weight of temperature controlled railway car  20  while at the same time increasing both internal volume and load carrying capacity as compared to a conventional refrigerated box car satisfying Plate F requirements. A composite box structure and associated insulated box car or temperature controlled railway car may be formed in accordance with teachings of the present invention to accommodate various geometric configurations and load carrying requirements to meet specific customer needs concerning size and temperature specifications of different types of lading carried in the resulting box car. 
     The term “composite box structure” refers to a generally elongated structure having a roof assembly, a floor assembly, a pair of side wall assemblies, and a pair of end wall assemblies which cooperate with each other to provide a generally hollow interior satisfactory for carrying different types of lading associated with insulated box cars and refrigerated box cars. Portions of the roof assembly, floor assembly, side wall assemblies, end wall assemblies and/or airflow management system may be formed from conventional materials such as steel alloys and other metal alloys used to manufacture railway cars. Portions of the roof assembly, floor assembly, side wall assemblies, end wall assemblies and/or airflow management system may also be formed from composite materials such as advanced thermal plastics, insulating foam, fiberglass pultrusions and ballistic resistant fabrics. Various types of composite materials may be used to form a roof assembly and all or portions of an airflow management system in accordance with teachings of the present invention. Examples of some of the materials used to form a roof assembly and/or airflow management system incorporating with teachings of the present invention will be discussed throughout this application. 
     The term “FRP” may be used to refer to both fiber reinforced plastic and glass fiber reinforced plastic. A wide variety of fibers in addition to glass fibers may be satisfactory used to form portions of a roof assembly and an airflow management system incorporating teachings of the present invention. 
     Composite box structure  30  may be formed from several major components including roof assembly  40 , side wall assemblies  50  and  52 , floor assembly  80  and end wall assemblies  120  and  122 . Major components associated with composite box structure  30  may be fabricated individually and then attached to or assembled on railway car underframe  200  to form temperature controlled railway car  20 . Individually manufacturing or fabricating major components of composite box structure  30  allows optimum use of conventional railcar manufacturing techniques. For example, side stakes and door posts may be welded with top cords and side sills using conventional railcar manufacturing techniques to provide structural members for a side wall assembly. Manufacturing procedures associated with thermoplastic materials and insulating foam may be modified in accordance with teachings of the present invention to form other portions of composite box structure  30 . 
     Various features of a roof assembly and an airflow management system formed in accordance with teachings of the present invention will be described with respect to temperature controlled railway car  20 . However, for some applications a roof assembly incorporating teachings of the present invention may be attached to or mounted on a conventional box car or refrigerated railway car during repair and/or rebuilding. In a similar manner all or portions of an air plenum assembly incorporating teachings of the present invention may be installed within a conventional insulated box car or conventional refrigerated box car during repair and/or rebuilding of the box car. A roof assembly and an airflow management system incorporating teachings of the present invention are not limited to use with temperature controlled railway car  20 . 
     For embodiments of the present invention as shown in  FIGS. 1A-4  portions of railway car underframe  200  may be manufactured and assembled using conventional railcar manufacturing procedures and techniques. Railway car underframe  200  includes a pair of railway car trucks  202  and  204  located proximate to each end of railway car underframe  200 . Standard railcar couplings  210  are also provided at each end of railway car underframe  200 . Each coupling  210  preferably includes end of car cushioning unit  212  disposed at each end of an associated center sill (not expressly shown). Railway car underframe  200  preferably includes a plurality of longitudinal stringers  230 . 
     For the embodiment of the present invention as shown in  FIGS. 1A-4  railway car underframe  200  preferably includes a plurality of longitudinal stringers  230  which extend approximately the full length of railway car underframe  200 . As shown in  FIG. 3 , railway car underframe  200  may include cross tie  216  and cross bearers  217  with longitudinal stringers  230  disposed thereon. Cross ties  216  and cross bearers  217  are attached to and extend laterally from center sill  214 . Longitudinal stringers  230  are preferably disposed on cross ties  216  and cross bearers  217  and extend parallel with center sill  214 . Cross ties  216  and cross bearers  217  are generally spaced laterally from each other extending from center sill  214 . The number of cross ties, cross bearers and longitudinal stringers may be varied depending upon the desired load carrying characteristics for the resulting railway car  20 . 
     Railway car underframe  200  also includes side sill assemblies  250  and  252  and end sill assemblies  220  and  222 . Side wall assemblies  50  and  52  may be fabricated with respective side sill assemblies  250  and  252  formed as integral components thereof. End wall assemblies  120  and  122  may also be fabricated with all or portions of respective end sill assemblies  220  and  222  formed as integral components thereof. 
     Side wall assemblies  50  and  52  have substantially the same configuration and overall design. Therefore, various features of composite box structure  30  will be discussed primarily with respect to side wall assembly  50 . See FIG.  2 . Side wall assembly  50  includes a plurality of metal side sheets  54  disposed on the exterior of composite box structure  30 . Exterior surfaces  53  of side sheets  54  cooperates with each other to form the exterior of side wall assembly  50 . See  FIG. 1A. A  plurality of support posts or side stakes  56  may be attached to portions of interior surface  55  of each side sheet  54 . Support posts  56  extend towards interior  32  of composite box structure  30 . 
     For some applications, isolator  60  formed from a thermoplastic polymer such as polyvinyl chloride (PVC) insulating material may be attached to interior surface or first surface  57  of each support post  56 . For other applications alternating blocks of PVC and blocks of insulating foam (not expressly shown) may be placed on first surface  57  of each support post  56 . Various thermoplastic polymers, urethane foams and other types of insulating material may also be attached to first surface  57  of each support post  56  to form isolators  60 . The present invention is not limited to use of PVC strips. 
     First layer  61  of polymeric material or FRP material may then be attached to isolators  60 . Foam insulation  58  may be disposed between adjacent support posts  56  and bonded with interior surface  55  of side sheets  54  and the interior surface of first layer  61  and adjacent portions of support posts  56 . For some applications a layer of scrim (not expressly shown) may be attached to the interior surface of first layer  61  to enhance bonding with foam insulation  58 . Second layer  62  of polymeric material or FRP material may be attached to first layer  61 . 
     First layer  61  and second layer  62  are preferably formed from tough, light weight, rigid material having high impact resistance. First layer  61  and second layer  62  cooperate with each other to form a liner for composite box structure  30 . For some applications first layer  61  and second layer  62  are preferably formed from Bulitex material available from U.S. Liner Company, a division of American Made, Inc. Bulitex material may be generally described as a ballistic grade composite scuff and wall liner. 
     Various types of ballistic resistant fabric may be satisfactorily used to form a liner for a composite box structure in accordance with teachings of the present invention. Ballistic resistant fabrics are often formed with multiple layers of woven or knitted fibers. The fibers are preferably impregnated with low modulus elastomeric material as compared to the fibers which preferably have a high modulus. U.S. Pat. No. 5,677,029 entitled “Ballistic Resistant Fabric Articles, and assigned to Allied Signal shows one example of a ballistic resistant fabric. First layer  61  and/or second layer  62  may be formed from other materials including fiber reinforced plastics, thermoplastics, polymers and copolymers. 
     Second layer  62  preferably includes a corrugated cross section which provides desired airflow paths  63  when lading is disposed adjacent to side wall assembly  50 . Airflow paths  63  form portions of airflow management system  300 . 
     For one application side sheets  54  may be formed from twelve (12) gauge steel. Support post  56  may be three (3) inch I beams. Isolators  60  may have dimensions of approximately two (2) inches by two (2) inches by three fourths (¾) of an inch. Foam insulation  58  may have a thickness of approximately four (4) inches. First layer  61  may be formed from Bulitex material having a thickness of approximately 0.06 inches. Second layer  62  may be formed from Bulitex material having a thickness of approximately 0.04 inches. The width of each corrugation formed in second layer  62  may be between approximately four (4) and five (5) inches. The corrugations form airflow path  63  spaced approximately one half (½) inch from first layer  61 . 
     End wall assemblies  120  and  122  may be formed using similar materials and techniques as described with respect to side wall assembly  50 . In side wall assembly  50 , support posts  56  extend generally vertically between side sill assembly  250  and associated top chord  64 . See FIG.  10 . End wall assemblies  120  and  122  may also be formed from 1 beams (sometimes referred to as “end beams”) having configurations similar to support posts  56 . However, I beams or end beams  126  disposed within end wall assemblies  120  and  122  preferably extend generally horizontally with respect to each other and railway car underframe  200 . For the embodiment of the present invention as shown in  FIG. 4 , end wall assemblies  120  and  122  include a plurality of end beams  126  respectively attached with metal sheets  54  and spaced from each other extending generally horizontally relative to floor assembly  80  and railway car underframe  200 . Metal sheets  54  may sometimes be referred to as “end sheets” when attached to end wall assemblies  120  and  122 . 
     Respective isolators  60  may be attached to interior surface or first surface  127  of each end beam  126 . First layer  61 , a polymeric material, may then be attached to isolators  60 . Foam insulation  58  may be disposed between and bonded with adjacent portions of end beams  126  interior surface  53  of metal sheets  54  and adjacent portions of first layer  61 . For purposes of illustrating various features of the present invention, portions of end wall assemblies  120  and  122  are shown with foam insulation  58  disposed therein. For most applications, end wall assemblies  120  and  122  will be filled with foam insulation  58  between respective first layer  61  and respective metal sheets  54 . 
     For the embodiment of the present invention as shown in  FIG. 4 , portions of end sill assemblies  220  and  222  are formed as integral components of respective end wall assemblies  120  and  122 . For one embodiment respective angles  221  may be securely attached with respective metal sheets  54  and bonded with associated foam insulation  58 . End sill assemblies  220  and  222  may also include respective C shaped channels  223 . The length of C shaped channels  223  approximately equals the width of railway car underframe  200  and the exterior width of composite box structure  30 . The respective ends of each longitudinal stringer  230  are preferably formed to receive portions of respective C shaped channels  223  and portions of respective angles  221 . Various welding techniques and/or mechanical fasteners may be satisfactory used to couple metal sheets  54  with respective angles  221 , angles  221  with respective C shaped channels  223  and end sill assemblies  220  and  222  with respective ends of longitudinal stringers  230 . 
     For some applications a plurality of pultruded panels  82  (see  FIGS. 4 ,  5  and  6 ) may be bonded with each other to form primary floor  100  having a generally rectangular configuration corresponding with the desired interior length and width of composite box structure  30 . The length of each pultruded panel  82  may correspond approximately with the interior width of composite box structure  30 . U.S. Pat. No. 5,716,487 entitled “Pultrusion Apparatus” assigned to Creative Pultrusion, Inc. describes one example of equipment and procedures which may be used to form pultrusion panels  82 . 
     After the desired number of pultruded panels  82  have been bonded with each other, the resulting primary floor  100  may be lowered from above between side wall assemblies  50  and  52  until primary floor  100  engages longitudinal stringers  230  and portions of side sills  250  and  252  (not expressly shown) and end sill assemblies  220  and  222 . See FIG.  4 . For other applications, primary floor  100  may be attached with railway car underframe  200  prior to attaching side wall assemblies  50  and  52 . End wall assemblies  120  and  122  may then be mounted on and attached to railway car underframe  200 . Next, roof assembly  40  may be mounted on and attached with side wall assemblies  50  and  52  and end wall assemblies  120  and  122  opposite from primary floor  100 . See  FIGS. 3 ,  4  and  5 . 
     For some applications selected portions of primary floor  100  may be adhesively bonded or securely attached with adjacent portions of railway car underframe  200 . Other portions of primary floor  100  which are not bonded with railway car underframe  200  may expand and contract relative to longitudinal stringers  230  as temperature changes occur within composite box  30 . For some applications restraining anchor assemblies  270  may be attached with adjacent portions of primary floor  100  and longitudinal stringers  230  to allow limited longitudinal movement of floor assembly  80  relative to railway car underframe  200  and substantially restrict vertical movement of floor assembly  80  relative to railway car underframe  200  during thermal expansion and contraction. See FIG.  3 . 
     As shown in  FIGS. 5 and 6  floor assembly  80  preferably includes primary floor  100  and secondary floor  110 . Secondary floor  110  may be formed by placing a plurality of support beams  112  on pultruded panels  82  opposite from railway car underframe  200 . Each support beam  122  may have a configuration or cross section corresponding with a typical I beam. A plurality of deck plates or coverings  116  may be placed on first surface  111  of each support beam  112 . Second surface  113  of each support beam  112  may be adhesively bonded or coupled with adjacent portions of pultruded panels  82 . Deck plates  116  may be adhesively bonded or coupled with first surface  111  of each support beam  112 . Alternatively, all or some deck plates  116  may be mechanically fastened with support beams  112  using various types of mechanical fasteners such as bolts, rivets and/or HUCK fasteners (not expressly shown). Support beams  112  and deck plates  116  may be formed from metal alloys or other materials typically associated with forming a floor. 
     A plurality of openings (not expressly shown) may be formed in each support beam  112  to enhance airflow or air circulation between primary floor  100  and secondary floor  110 . As shown in  FIG. 5 , airflow paths formed between primary floor  100  and secondary floor  110  provide a portion of airflow management system  300 . 
     Roof assembly  40  may be formed with a generally elongated, rectangular configuration. The length and width of roof assembly  40  corresponds generally with desired length and width of resulting composite box structure  30 . Roof assembly  40  includes first longitudinal edge  41  and second longitudinal edge  42  spaced from each other and extending generally parallel with each other from first lateral edge  43  to second lateral edge  44 . Roof assembly  40  may have a generally arcuate configuration extending from first longitudinal edge  41  to second longitudinal edge  42 . See  FIGS. 5 and 10 . Longitudinal edges  41  and  42  are preferably mounted on and attached with respective side wall assemblies  50  and  52 . See  FIGS. 5 and 10 . Lateral edges  43  and  44  are preferably mounted on and attached with respective top plates  130  of end wall assemblies  120  and  122 . See FIG.  4 . 
     Various types of composite materials and insulating materials may be satisfactory used to form a roof assembly incorporating teachings with the present invention. For the embodiment of the invention as shown in  FIGS. 4 ,  5  and  10 , roof assembly  40  may be formed from one or more FRP layers  45  and  46 . Each FRP layer may be formed from multiple panels or sheets of FRP. For the embodiment shown in  FIG. 4 , FRP layer  45  provides outer surface  38  of roof assembly  40 . FRP layer  46  provides interior  39  surface of roof assembly  40 . The number of FRP layers may be varied depending upon the planned use of resulting roof assembly  40 . 
     FRP layers  45  and  46  are preferably bonded with each other to encapsulate insulating layer  47  therebetween. For some applications insulating layer  47  may be formed from the same materials used to form foam insulation  58 . However, any material having desired thermal insulating characteristics may be satisfactory used to form insulating layer  47 . 
     A plurality of generally Z shaped beams or stiffeners  48  may be disposed within roof assembly  40  between FRP layers  45  and  46 . For some applications stiffeners  48  preferably extend laterally from first longitudinal edge  41  to second longitudinal  42  of roof assembly  40 . Stiffeners  48  may be spaced from each other throughout the length of roof assembly  40 . Various types of adhesive and/or fasteners may be satisfactory used to attach stiffeners  48  with adjacent portions of FRP layers  45  and  46 . For some applications resins associated with vacuum infusion of roof assembly  40  may also be used to bond stiffeners  47  with FRP layers  45  and  46 . 
     The perimeter of roof assembly  40  may include multiple layers of FRP material to provide appropriate strength required to adhesively bond with respective portions of side wall assemblies  50  and  52  and end wall assemblies  120  and  122 . Strips of trim molding  74  are preferably bonded with and attached to roof assembly  40  at respective flexible joints with end wall assemblies  120  and  122 . Strips of trim molding  75  are preferably bonded with and attached to end wall assembly  120  and  122  at respective flexible joints with primary floor  100 . See FIG.  4 . 
     Trim moldings  76  are preferably bonded with and attached longitudinally along respective flexible joints formed between roof assembly  40  and side wall assemblies  50  and  52 . See  FIGS. 5 and 10 . Trim molding  74 ,  75  and  76  accommodate limited expansion and contraction of respective flexible joints and flexible connects associated with composite box structure  30  while at the same time maintaining desired structural integrity of interior  32 . An example of trim molding  76  is shown in FIG.  10 . Various types of FRP materials may be satisfactory used to form trim molding  74 ,  75  and  76 . Door assemblies  180  may be slidably mounted on side wall assemblies  50  and  52  to control access to interior  32  through respective openings  36 . 
     Temperature control system  140  preferably includes refrigeration unit or cooling unit  142  and airflow management system  300  to provide substantially uniform, constant airflow around and through lading carried within composite box structure  30 . For some applications such as transporting products in sub-zero, winter environments temperature control system  140  may include a heater. Refrigeration unit  142  may be a self-contained refrigeration unit including a compressor (not expressly shown), a condenser (not expressly shown), airflow blowers (not expressly shown), an external fuel tank  219  and a diesel engine (not expressly shown). For some applications, refrigeration unit  142  may provide airflow in the range of 3200 CFM. Self-contained refrigeration unit  142  provides the advantage of easier and faster maintenance as compared to conventional refrigerated box cars with similar performance characteristics. As a result, temperature control system  140  generally lowers maintenance time and costs and increases the amount of time that temperature controlled railway car  20  remains in service between repairs. 
     Refrigeration unit  142  may be a programmable unit able to control and maintain desired temperatures within composite box structure  30 . Refrigeration unit  142  may include a keypad (not expressly shown) for inputting data for desired system performance and a microprocessor to control and monitor the functions and performance of refrigeration unit  142  and temperature control system  140 . Refrigeration unit  142  may also include a satellite monitoring and control system (not expressly shown) and/or cellular technology to transmit to remote locations information such as the performance and location of refrigeration unit  142  or the temperature inside composite box structure  30 . Various types of refrigeration systems are commercially available from companies such as Thermo King and Carrier. Such units are frequently used in motor carrier trailers and other large containers. 
     As shown in  FIGS. 1A and 1B , refrigeration unit  142  may be mounted on end wall assembly  120 . Refrigeration unit  142  may be mounted on the exterior of end wall assembly  120  using mounting bolts  128  and associated supports  129  disposed within end wall assembly  120 . The number of mounting bolts  128  may be varied depending on the size and weight of associated refrigeration unit  142 . 
     End platform system  260  may be coupled to railway car underframe  200  near refrigeration unit  142  to provide access to refrigeration unit  142 . External fuel tank  219  may be located proximate to refrigeration unit  142 . This provides the benefit of convenient access to both fuel tank  219  and refrigeration unit  142 . 
     Airflow management system  300  provides relatively uniform distribution of air at a desired temperature throughout the length, width and height of interior  32  of composite box structure  30 . Airflow management system  300  allows cooled air to circulate from refrigeration unit  142 , around and through products or lading contained within composite box structure  30 , and back to refrigeration unit  142 . Airflow management system  300  may also be capable of circulating fresh air from outside composite box structure  30  or heated air throughout the interior portion of composite box structure  30 . 
     Depending on the intended application for composite box structure  30  and associated railway car, refrigeration unit  142  may or may not be used in conjunction with airflow management system  300 . Also, because of superior insulating characteristics of composite box structure  30 , refrigeration unit  142  may not be necessary for particular products and operating environments, to maintain satisfactory temperature regulation of some types of products within composite box structure  30 . For these applications, satisfactory air temperatures may be maintained within composite box structure  30  either without using temperature control system  140 , or by using only airflow management system  300  to circulate fresh air throughout composite box structure  30 . The present invention provides benefits of a more diverse box car having the capability of transporting a wide variety of freight, including frozen products, fresh products, dry food or non-food products which do not require refrigeration or temperature control. 
     Airflow management system  300  includes a number of features which keep products shipped within composite box structure  30  spaced from the interior surfaces of the side wall assemblies  50  and  52 , end wall assemblies  120  and  122 , and primary floor  100  to create openings or gaps for airflow around the products. These features include air plenum assembly  310 , secondary floor  110 , interior bulkhead or end barrier  280 , and corrugations or airflow paths  63  formed by second layer  62 . Some features of airflow management system  300  may slightly reduce volumetric carrying capacity of composite box structure  30 . However, improved airflow around and through products shipped inside composite box structure  30  achieves desired temperature regulation of such products and more than compensates for any volumetric reduction. 
     Airflow management system  300  includes air plenum assembly  310 . See  FIGS. 3 ,  5 ,  6 ,  7 A and  7 B. Air plenum assembly  310  may be coupled with temperature control unit  142  to provide portions of an airflow path to supply air from temperature control unit  142  to interior  32  of composite box structure  30 . Air plenum assembly  310  has a generally elongated, rectangular configuration. The length of air plenum assembly  310  is approximately equal to the interior length of composite box structure  30 . The width of air plenum assembly  310  is generally less than the interior width of composite box structure  30 . See  FIGS. 5 and 6 . 
     Interior bulkhead or end barrier  280  may be formed within composite box structure  30  adjacent to end wall assembly  120 . For the embodiment of the present invention as shown in  FIGS. 6 and 12 , interior bulkhead  280  may be formed by attaching a plurality of support beams  284  and a plurality of panels  282  with each other. Various types of supporting structures other than support beams  284  may be used to form interior bulkhead  280 . 
     For one application support beams  284  have a cross section corresponding with a conventional I beam. Each support beam preferably includes a respective web  285  with a plurality of openings  288  formed therein. Openings  288  allow increased circulation of airflow between interior bulkhead  280  and adjacent portions of end wall assembly  120 . 
     Panels  282  may be attached to or mounted on support beams  284  using various techniques such as adhesive and/or mechanical fasteners. A portion of mechanical fastener  299  used to attach panel  282  with support beam  284  is shown in FIG.  12 . For some applications panels  282  may be formed, using pultrusion techniques, with a plurality of slots (not expressly shown). Attaching inserts (not expressly shown) may be disposed within one or more slots for use in attaching each panel  282  with associated support beams  284 . 
     Opening  146  is preferably formed in interior bulkhead  280  to provide access to refrigeration unit  142 . See FIG.  6 . Also, a panel or door (not expressly shown) may be hinged adjacent to opening  146  to control and limit access to refrigeration unit  142 . Air flowing between primary floor  100  and secondary floor  110  is preferably directed towards the lower portion of interior bulkhead  280  and then flows upward between support post  284  to return to refrigeration unit  142 . As shown in  FIG. 12  interior bulkhead  282  is preferably spaced from adjacent portions of side wall assemblies  50  and  52 . Arrow  302  represents air flowing between interior barrier  280  and adjacent portions of side wall assembly  50  and through opening  288  in web  285 . 
     Plenum panels  318  and  319  preferably have respective openings  324  formed therein and extending through at approximately the center of each panel. Openings  324  will be discussed later with respect to hanger assemblies  30 . Additional openings  328  may also be formed in plenum panels  318  and  319  to allow limited airflow from air plenum assembly  310  to interior  32  of composite box structure  30 . The number of openings  328  and the pattern of openings  328  formed in each plenum panel  318  and  319  may be varied depending upon desired airflow characteristics and/or the type of lading which will be carried within railway car  20 . 
     Longitudinal connectors  340  and  342  are preferably disposed along opposite sides of air plenum assembly  310  extending from first end  311  to second end  326 . Connectors  340  and  342  may be attached to or bonded with the respective longitudinal edge of air plenum assembly  310  and adjacent portions of roof assembly  40 . See  FIG. 5. A  plurality of openings  344  may be formed in each longitudinal connector  340  and  342  to allow limited airflow from air plenum assembly  310  outwardly towards adjacent side wall assemblies  50  and  52 . The number, size and location of openings  344  may be varied to provide desired airflow from air plenum assembly  310  to flow paths  63  formed by corrugations associated with respective side wall assemblies  50  and  52 . See FIG.  5 . 
     Respective plenum panels  318  are generally disposed immediately adjacent to each other. A respective connector  346  is preferably coupled with adjacent longitudinal edges of each plenum panel  318 . See FIG.  8 . In addition to providing support for air plenum assembly  310 , connectors  346  prevent undesired airflow between adjacent plenum panels  318 . 
     As shown in  FIG. 7B , second end  326  of air plenum assembly  310  may be coupled with a plurality of airflow paths formed along the interior of end wall assembly  122 . Airflow paths  348  may be formed on the interior surface of end wall assembly  122  using various techniques. For some applications second layer  62  may be attached to end wall assembly  122  to provide airflow paths  348 . For other applications a plurality of extruded panels  282 , having a plurality of slots formed therein, may be attached with end wall assembly  122 . Pultruded panels  282  are preferably oriented with respective slots extending generally vertically between air plenum assembly  310  and floor assembly  80  to provide airflow paths  348 . As a result, an airflow path may be provided from second end  326  of air plenum assembly  310  through airflow paths  348  formed on the interior of end wall assembly  122  and into the space formed between primary floor  100  and secondary floor  110 . Trim molding  347  may also be attached adjacent to second end  326  of air plenum assembly  310  and airflow path  348 . 
     Chute assembly  312 , attached to first end  311  of air plenum assembly  310 , provides an airflow path from temperature control unit  142  to air plenum assembly  310 . Chute assembly  312  preferably includes one or more supports  314  which may be disposed on and attached to an upper portion of interior bulkhead  280  adjacent to temperature control unit  142 . Transition panel  316  may be attached with support  314  extending at an angle from adjacent portions of interior bulkhead  280  to air plenum assembly  310 . First side panel  321  and second side panel  322  are respectively attached to opposite edges of transition panel  316  to further direct airflow from temperature control unit  142  to air plenum assembly  310 . Support  314 , panel  316  and side panels  321  and  322  may be formed from aluminum or other satisfactory lightweight material. Chute assembly  312  may be described as a chute assembly with respect to temperature control unit  142  or as an inlet chute with respect to air plenum assembly  310 . 
     Air plenum assembly  310  may be formed from a plurality of plenum panels  318 . Each plenum panel  318  may have substantially the same overall configuration and dimensions. For some applications plenum panel  319  with a reduced width as compared with plenum panels  318  may be disposed at second end  326  of air plenum assembly  310  opposite from chute assembly  312 . 
     Plenum panels  318  and  319  preferably have a generally rectangular configuration. Plenum panels  318  and  319  may be formed from a variety of FRP materials and/or lightweight metals. For some applications plenum panels  318  and  319  may be formed from Bulitex material similar to the material used to form first layer  61  and second layer  62 . 
     A respective hanger assembly  330  may be used to attach each plenum panel  318  and plenum panel  319  with interior surface  39  of roof assembly  40 . Each hanger assembly  330  preferably includes first support  331  and second support  332 . Flexible cable assembly  334  may be securely engaged with first support  331  and releasably engaged with second support  332 . For the embodiment of the present invention as shown in  FIG. 9 , opening  338  is preferably formed within second support  332 . A portion of flexible cable assembly  334  may be inserted through opening  338 . Pin  336  may be inserted through another opening formed in flexible cable anchor assembly  334  to releasably engage second support  332  with flexible cable assembly  334 . 
     Hanger assembly  330  may also include third support  333 . Third support  333  is preferably spaced from second support  332  such that portions of associated plenum panel  318  may be disposed therebetween. For the embodiment of the present invention as shown in  FIG. 9 , first support  331 , second support  332 , and third support  333  may have a generally circular, disk shaped configuration. A pair of mechanical fasteners  349  and  350  may be used to attach first support  331  with interior surface  39  of roof assembly  40 . For some applications, hanger assemblies  330  are preferably disposed along the longitudinal center line of roof assembly  40 . For other applications, the number and location of hanger assemblies  330  may be varied depending upon the desired configuration of the associated air plenum assembly. The exterior dimensions of third support  333  are preferably smaller than the diameter of opening  324  in the associated plenum panel  318 . 
     Fasteners  349  and  350  may be used to attach the respective first support  331  at a desired location on interior surface  39  of roof assembly  40 . Pin  336  may be removed from flexible cable assembly  334  to release second support  332  and third support  333  therefrom. The associated plenum panel  318  may then be positioned with a portion of flexible cable assembly  334  extending through respective opening  324 . The portion of flexible cable anchor assembly  334  may then be inserted through opening  338  in second support  332  and pin  336  inserted therein. As a result, plenum panel  318  will be disposed between second support  332  and third support  333 . 
     Flexible cable assembly  334  including second support  332  and third support  333  allows limited movement or flexing of plenum panels  318  and  319  relative to each other. For example, during loading and/or unloading of composite box structure  30 , plenum panels  318  may be raised or moved upwardly if contacted by a fork lift or other equipment used to load composite box structure  30 . Allowing limited movement of plenum panels  318  and  319  relative to each other and roof assembly  40  substantially reduces maintenance requirements associated with air plenum assembly  310 . 
     One temperature controlled railway car formed in accordance with teachings of the present invention has the following features:
         286,000 lb. Gross Rail Load;   Standard car equipped with 10′-0″ wide by 11′-3½″ high insulated single plug door;   15″ end-of-car cushioning unit;   Meets AAR Plate “F” Clearance Diagram;   State-of-the art temperature control unit, exterior service platform and interior access door;   Satellite monitoring and control system;   An airflow management system installed in the interior of the composite box structure;   High performance insulating materials;   Durable, wood free interior materials; and   No ferrous metals in the interior.       

     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Length Inside 
                 72′-2″ 
               
               
                   
                 Length Over Coupler Pulling Faces 
                 82′-2″ 
               
               
                   
                 Length over Strikers 
                 77′-10″ 
               
               
                   
                 Length Between Truck Centers 
                 52′-0″ 
               
               
                   
                 Truck Wheel Base 
                  5′-10″ 
               
               
                   
                 Width, Extreme 
                 10′-6⅝″ 
               
               
                   
                 Width, Inside 
                  9′-2″ 
               
               
                   
                 Height, Extreme 
                 16′-11⅞″ 
               
               
                   
                 Height Inside at Center Line of Car 
                 12′-1½″ 
               
               
                   
                 Estimated Lightweight 
                 105,000 lbs. 
               
               
                   
                 Estimated Load Limit - 
                 181,000 lbs. 
               
               
                   
                 Based on 286,000 lbs. Gross Rail Load 
               
               
                   
                 Gross Rail Load 
                 286,000 lbs. 
               
               
                   
                 Cubic Capacity (Between bulkheads) 
                 8,012 cubic feet 
               
               
                   
                 Cubic Capacity 
                 7,883 cubic feet 
               
               
                   
                 (Level with height of sides) 
               
               
                   
                   
               
            
           
         
       
     
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the following claims.