Abstract:
Provision is made for a single person to easily install a bottom panel for the cover of a transport refrigeration unit. A plurality of forwardly extending tabs are spaced on a rear frame member and corresponding pockets with horizontal slots are similarly spaced near the rear edge of the bottom panel. The bottom panel is then advanced such that the tabs fit into the slots, and then the front portion of the bottom panel is attached to the framework by a plurality of fasteners passing through front pockets of the bottom cover and into L-shaped brackets mounted on a front portion of the frame. The bottom panel is preferably formed of a thermoplastic olefin material that provides flexibility for ease of assembly but is sufficiently rigid and strong and exhibits good sound absorbing characteristics.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the art of transport refrigeration units and in particular to outer protective covers for such units. 
       BACKGROUND OF THE INVENTION 
       [0002]    A typical transport refrigeration unit of the type designed for mounting on the front face of a tractor trailer unit comprises a one piece, self-contained fully refrigerant charged, prewired, refrigerant/heating unit powered by a diesel engine. In such a design the evaporator fits into a rectangular opening in the upper portion of the trailer front wall. When installed, the evaporator section is located inside the trailer; and the condensing section is outside and on the front of the trailer. The condensing section consists of an engine-compressor drive package, condenser fan, condenser coil, radiator coil, control panel, relay module, refrigerant controls, piping, wiring and associated components. 
         [0003]    Structural frame means support all of the components and facilitate attaching of the unit to the trailer front face. Also supported by the structural framework is an outer cover which includes the necessary air inlet and outlet openings for cooling, and which may be opened to provide access to the interior of the unit for maintenance and service. 
         [0004]    Such refrigeration units preferably have a bottom panel to hide components, wiring, and the like and to improve aesthetics of the underside of the unit. Traditionally this has been provided in the form of a two piece bottom panel that was secured to the underside by way of fasteners. For the assembly of such a panel, it was necessary to have one person holding the panels in place while another person secured them to the bottom by way of fasteners. 
         [0005]    A bottom cover should not only be simple in construction with as few parts as possible but should also be easy to assemble, be of lost cost and weight, while at the same time providing superior appearance and reliability. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with one aspect of the invention, a bottom panel for a transport refrigeration unit is a unitary member which can be easily attached to the frame of the unit by a single installer placing the panel in position and securing it by fasteners. 
         [0007]    By another aspect of the invention, the unit frame has a plurality of horizontally extending tabs attached thereto and the bottom cover has a plurality of matching slots near the rear edge thereof. The cover is easily installed by placing the bottom cover in position with the slots registering with the frame tabs and then securing the cover in position with fasteners near its front edge. 
         [0008]    In accordance with another aspect of the invention, the unit frame also includes a plurality of mounting angles that are fastened to the front portion of the frame with the mounting angles being adapted to receive fasteners therein. The bottom cover is then placed under the mounting angles and secured thereto by way of fasteners. 
         [0009]    By yet another aspect of the invention, the bottom cover panel is formed of a thermoplastic olefin material. 
         [0010]    In the drawings as hereinafter described, a preferred embodiment is depicted; however, various other modifications and alternate constructions can be made thereto without departing from the true spirit and scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a transport refrigeration unit with the present invention incorporated therein. 
           [0012]      FIG. 2  is a perspective view of the framework for a trailer refrigeration unit in accordance with the present invention. 
           [0013]      FIG. 3  is a perspective view of the cover bottom panel as seen from above in accordance with the present invention. 
           [0014]      FIG. 4  is a perspective view of the cover bottom panel as seen from below in accordance with the present invention. 
           [0015]      FIG. 5  is a top view of the bottom panel in accordance with the present invention. 
           [0016]      FIG. 6  is a sectional view thereof as seen along lines  6 - 6  of  FIG. 5 . 
           [0017]      FIG. 7  is an exploded view of the unit frame and cover bottom panel. 
           [0018]      FIG. 8  is a perspective view of a mounting bracket in accordance with one aspect of the invention. 
           [0019]      FIG. 9  is a perspective view of the installed bottom panel as seen from below. 
           [0020]      FIG. 10  is a perspective view of the installed bottom panel as seen from above. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    In  FIG. 1  a fragmentary front part of a large transport trailer  10  is shown with a transport refrigeration unit  11  mounted on the front wall  12  of the trailer. For purposes of the present description the terms “roadside” and “curbside” will be used in describing various components of the refrigeration unit and its cover. As viewed in  FIG. 1 , the right hand side of the unit will be referred to as the roadside and the left hand side of the unit as the curbside of the unit. 
         [0022]    With this reference, the unit as illustrated in  FIG. 1  has the curbside front door  14 , and, the roadside front door  16  of the unit cover in their closed positions but containing the inner structural components of the unit as well as some of the components of the refrigeration unit itself. Attachment of the refrigeration unit  11  to the trailer  10  is carried out by connection of an outer peripheral planar structural steel framework illustrated generally by reference numeral  20 . It should be appreciated that this framework is not normally visible when the unit is properly installed on a trailer unit, however for purposes of illustration, at least a portion of the structural framework is illustrated in  FIG. 1 . 
         [0023]    All of the component assemblies which define the outer cover of the refrigeration unit  11  are mounted to the various structural components. Each of the doors forming the lower portion of the cover are made from a tough, light-weight composite material designed to resist rust, denting, warping, fading or peeling of their outer finish. These components include the front curbside door  14  and the front roadside door  16  previously referred to above. They also include the curbside outer door  15  and roadside outer door  17 . 
         [0024]    The front doors  14  and  16  are vertically hinged at their respective outer edges to provide a large access opening at the front of the unit. The side doors  15  and  17  are vertically hinged at their rear edges such that they pivot open from front to back. Latches  18  and  19  are provided for latching and unlatching the front roadside door  16  and side roadside door  17 , respectively. 
         [0025]    The upper part of the unit cover comprises a rigid front grille member  40  and a flexible support structure  41  disposed in surrounding relationship therewith. The grille member  40  is positioned in overlying relationship with the condenser heat exchanger of the refrigeration unit and is provided with a large number of openings  42  therethrough to facilitate air flow for efficient heat transfer. The support member  41  is secured to the frame  20  and the front grille is fastened to the support structure  41  by appropriate fastening means as at  44 . 
         [0026]    A cover bottom panel  25  is attached to the unit in a manner to be described hereinafter. 
         [0027]    It will be appreciated therefore that the door and grille components, as well as the cover bottom panel, as described above are designed to cooperate to fully enclose the refrigeration unit  11  to provide protection from the environment and road hazards and to aerodynamically and aesthetically enhance the unit. 
         [0028]    Referring now to  FIGS. 2-10 , the features of the cover bottom panel  25  and the manner in which it is attached will now be described. Referring to  FIG. 2 , the steel structural framework for attaching the transport refrigeration unit  11  and its cover to the front wall  12  of the trailer is shown at  20 . Its components include the rear vertical members  51  and  52 , front vertical members  53  and  54 , rear horizontal members  56 ,  57  and  58 , and a front horizontal member  59 , all of which are secured together to form a rigid framework. Interconnecting the rear horizontal member  58  and the front horizontal member  59  are the horizontal tie members  61  and  62 . 
         [0029]    Secured, by welding or the like, to the front face of the front horizontal member  59  are L-brackets  63  and  64 . Similarly, L-brackets  66  and  67  are secured to the front face of the rear horizontal member  58  as shown. Each of the L-brackets has a hole formed in the extended leg for purposes of securing the frame  20  to a pallet. Thus, they are not related to the present invention. 
         [0030]    Also attached to the rear horizontal member  58  are the forwardly extending tabs  68 ,  69 ,  71 ,  72  and  73  as shown. The purpose of these tabs is to provide an easy and effective method of attaching the bottom cover to the framework  20  in a manner to be described hereinafter. 
         [0031]    The bottom panel, to be attached to the framework  20  to form the bottom portion of the outer cover for purposes of closure and to improve the aesthetics of the underside of the unit, is shown at  74  in  FIGS. 3-6 , with  FIG. 3  being a top perspective view,  FIG. 4  being a bottom perspective view,  FIG. 5  being a top view and  FIG. 6  being a sectional view thereof. The panel  74  comprises a planar member  76  having a straight rear edge  77  and a curved front edge  78  as shown. An upwardly extending ridge  79  is disposed around the rear and front edges  77  and  78  to provide an interface with the other portions of the outer cover. For example, the ridge  79  on the front edge  78  interfaces with the lower edge of the access doors of the cover. As it will be seen, there are spaces  81  and  82  in which the ridge  79  does not extend, since these are the spaces between the respective front and side doors. 
         [0032]    At the rear edge  77  of the panel there are provided three indentions  83 ,  84  and  86  which allow for the insertion of wire harnesses. 
         [0033]    Located near the rear edge  77  are five identical pockets  87  which extend upwardly from the planar member  76  in a generally cylindrical manner. In the rear side of each of the pockets is a slot  88  that extends forwardly into the pocket  87 . This can best be seen in the cross sectional view of  FIG. 6 . The purpose of these pockets  87  and slots  88  is to facilitate the attachment of the panel  74  to the frame  20  in the manner to be described hereinafter. 
         [0034]    Located near the front edge  78  of the panel  74  are five identical pockets  89  extending upwardly from the planar member  76  in a generally cylindrical manner and having an opening  91  centrally disposed therein. A cross sectional view thereof is shown in  FIG. 6 . The purpose of these pockets  89  are to facilitate the attachment to the frame  20  by way fasteners in the manner to be described hereinafter. 
         [0035]    The bottom panel  74  is a one-piece injection molded part which is sufficiently flexible to allow for easy assembly with the frame  20 , but also provide sufficient rigidity and strength to provide a robust and durable undercover for the unit. A preferred material is a thermoplastic olefin (TPO). Another olefinic material may also be used. One advantage of such a material, in addition to its strength and flexibility, is that it provides excellent damping characteristics as compared with a metallic member or a rigid thermoplastic/thermoset material, and the need for additional sound/foam installation is not required. 
         [0036]    Referring now to  FIGS. 7-10 , the manner in which the bottom panel  74  is attached to the frame  20  will now be described. Provision is first made for attachment of the bottom panel  74  to the front horizontal member  59  of the frame  20 . This is accomplished by attaching five L-shaped brackets  92  to the framework  20 . The L-shaped brackets  92  are shown in  FIG. 8  and include an integrally attached, upstanding cylinder  93  in the lower leg and a hole  94  in the upper leg. The hole  94  is for purposes of attaching the bracket  92  to the framework, and the cylinder  93  is used for attachment of the bottom panel  74  to the brackets  92 . 
         [0037]    As will be seen in  FIG. 7 , three of the brackets  92  are attached to the front face of the front horizontal member  59  by way of fasteners passing through the hole  94 . The other two brackets  92  are attached, one each, to each of the diagonal members  65 , but on the inner surface thereof. We are now ready to attach the bottom panel  74  to the framework  20 . 
         [0038]    First a bubble gasket  96  is placed on the upwardly extending edge  79  of the panel front edge  78 . This is accomplished by U-clipping it over the ridge  79  and provides for an improved interface with the lower edges of the doors that interface therewith. 
         [0039]    A single person assembly of the panel  74  to the frame  20  can then be made by registering the slots  88  of the covers  74  over the tabs  68  on the rear horizontal member  58  of the frame. The slots  88  are of sufficient size to provide easy registry with the tabs  68 - 73 , while at the same time providing a relatively tight fit when in the installed position. The TPO material is very suitable for this purpose. 
         [0040]    The next step is to align the pockets  89  with the L-shaped brackets  92  such that fasteners can be passed through the opening  91  in the pockets  89  and then engage with the inner surface of the cylinder  93  to fixedly secure the bottom cover  74  in place. The bottom cover  74  is shown in its installed condition in  FIGS. 9 and 10 .