Abstract:
A duct ( 100 ) comprises the molded combination of: an inlet flange ( 110 ) surrounding an inlet ( 102 ), the inlet having a height and a width; and body ( 112 ) extending from the inlet to an outlet ( 104 ) and having a body interior that laterally outwardly diverges and upwardly shifts from the inlet toward the outlet.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    Benefit is claimed of U.S. Patent Application Ser. No. 61/814,699, filed Apr. 22, 2013, and entitled “Refrigerated Container and Duct Extension”, the disclosure of which is incorporated by reference herein in its entirety as if set forth at length. 
     
    
     BACKGROUND 
       [0002]    The disclosure relates to transport refrigeration. More particularly, the disclosure relates to air handling in transport refrigeration systems. 
         [0003]    Transport refrigeration systems include cargo/shipping containers, trailers, and trucks. Each involves one or more refrigerated compartment and a refrigeration system positioned to cool a recirculating airflow within the compartment. Depending upon the implementation, refrigeration equipment may be mounted to an exterior of the container or within a subcompartment in the container. 
         [0004]    Many truck and trailer configurations mount the equipment to the front of the container, often high on the front wall so that the outlet for discharging cooled air into the compartment is near the compartment ceiling. 
         [0005]    It has been proposed to use a duct extension or chute (duct) to discharge cooled air further back in the container. In one example, a blow-molded open-top duct has a forward flange that mates to the equipment compartment and an upper flange that mates to the ceiling. The duct body transitions from a rectangular (bottom and two sides) portion near the inlet flange to an arcuate cross-section near a rear rim. 
       SUMMARY 
       [0006]    One aspect of the disclosure involves a duct comprising the molded combination of an inlet flange and a body. The inlet flange surrounds an inlet having a height and a width. 
         [0007]    The body extends from the inlet to an outlet and has a body interior that laterally outwardly diverges and upwardly shifts from the inlet toward the outlet. 
         [0008]    In one or more embodiments of any of the foregoing embodiments, the duct comprises thermoplastic polyolefin. 
         [0009]    In one or more embodiments of any of the foregoing embodiments, the duct is twin-sheet thermoformed. 
         [0010]    In one or more embodiments of any of the foregoing embodiments, the duct comprises a proximal trunk and a plurality of distal branches. 
         [0011]    In one or more embodiments of any of the foregoing embodiments, a plurality of walls divide the distal branches, each wall comprising at least one portion protruding upward from a bottom of the body and at least one portion protruding downward from a top of the body and meeting. 
         [0012]    In one or more embodiments of any of the foregoing embodiments, one or more of the walls includes an interrupted portion wherein the wall protrudes upward from the bottom of the duct to a non-recessed location on the top of the duct. 
         [0013]    In one or more embodiments of any of the foregoing embodiments, the interrupted portion includes a mounting hole. 
         [0014]    In one or more embodiments of any of the foregoing embodiments, the duct further comprises a plurality of tabs at the outlet, each tab includes a mounting a hole. 
         [0015]    Another aspect of the disclosure involves a transport refrigeration system including the duct of any of the foregoing embodiments and further comprising: a container and a refrigeration system. The refrigeration system includes: a fan for driving air along a flowpath from an inlet to an outlet; and a heat exchanger along the flowpath for cooling the air. The duct is mounted so that its inlet receives air from the refrigeration system outlet. 
         [0016]    In one or more embodiments of any of the foregoing embodiments, the refrigeration system is mounted along a front wall of the container. 
         [0017]    In one or more embodiments of any of the foregoing embodiments, the duct comprises a proximal trunk and a plurality of distal branches. 
         [0018]    Another aspect of the disclosure involves a method for making the duct of any of the foregoing embodiments. The method comprises: providing a first sheet and a second sheet; vacuum thermoforming the first sheet and the second sheet; and pressing the thermoformed first sheet and thermoformed second sheet together so as to fuse the first and second sheets together. 
         [0019]    Another aspect of the disclosure involves a method for using the duct of any of the foregoing embodiments. The method comprises attaching the flange to an outlet of a refrigeration system of a transport container. 
         [0020]    In one or more embodiments of any of the foregoing embodiments, the method further comprises attaching the duct body to a ceiling of the container. 
         [0021]    In one or more embodiments of any of the foregoing embodiments, the attaching the duct body to the ceiling comprises screwing through tabs protruding from an upper portion of the duct at the outlet. 
         [0022]    In one or more embodiments of any of the foregoing embodiments, the attaching of the duct body to the ceiling comprises screwing through upwardly projecting pockets. 
         [0023]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a simplified side sectional view of a refrigerated transport system. 
           [0025]      FIG. 1A  is an enlarged view of an equipment box region on the system of  FIG. 1 . 
           [0026]      FIG. 2  is an aft oblique view of the equipment box. 
           [0027]      FIG. 3  is a first view of a duct extension. 
           [0028]      FIG. 4  is a second view of the duct extension. 
           [0029]      FIG. 5  is a third view of the duct extension. 
           [0030]      FIG. 6  is a bottom view of the duct extension. 
           [0031]      FIG. 7  is a front view of the duct extension. 
           [0032]      FIG. 8  is a side view of the duct extension. 
       
    
    
       [0033]    Like reference numbers and designations in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0034]      FIG. 1  shows a refrigerated transport system in the form of a trailer  20  having a container in the form of box  22  with an interior  24 . In the exemplary box, a pair of doors  26  are formed at a rear of the box. An equipment compartment  28  is located along a front of the box and contains the refrigeration system  30 . 
         [0035]    The exemplary refrigeration system  30  includes a vapor compression system comprising a compressor  32 . Sequentially downstream of the compressor along the refrigerant flowpath are a heat rejection heat exchanger  34  (e.g., condenser or gas cooler), an expansion device  36  (e.g., electronic expansion valve (EEV)), and a heat absorption heat exchanger (evaporator)  38 . These are connected via an appropriate refrigerant line. The exemplary heat exchangers are refrigerant-air heat exchangers and may have associated fans  40 ,  42  driving air flows thereacross. An exemplary air flow across the condenser  34  is shown as  500  and an exemplary air flow across the evaporator is shown as  502 . In various implementations, the box may also contain a power source such as an internal combustion engine driving an electric generator to, in turn, power the compressor and fan(s). Alternative implementations, may involve use of vehicle electric power. 
         [0036]    An exemplary box  22  is formed of an insulated wall structure  50  on the front, top, bottom, and left and right sides with the doors  26  also being insulated. The exemplary wall  50  has at least one penetration associated with the refrigeration system. In the exemplary embodiment, the penetration involves a rear protrusion or bay  52  of the equipment box extending from a lower end  54  to an upper end  56  within an aperture  58  of the front wall. The bay  52  defines a duct  60  extending from an inlet  62  low along an aft wall of the bay to an outlet  64  high along the aft wall. Within the duct, along an air flowpath are the evaporator and its associated fan. The exemplary outlet  64  is rectangular having a height and a width. The upper end of the outlet  64  is downwardly spaced from the ceiling  70  of the box. 
         [0037]    To better distribute the air discharged from the outlet  64 , a duct extension (duct)  100  is provided having an inlet  102  at the outlet  64  and an outlet  104  spaced forwardly and upwardly therefrom (e.g., adjacent to the ceiling surface  70 ).  FIG. 2  shows a forward portion of the box schematically. In many typical implementations, the box may be taller and wider relative to the refrigeration unit. The outlet  104  has a height and a width. In the exemplary embodiment, the outlet  104 &#39;s height is less than the height of the outlet  64  and its width is greater than the width of the outlet  64  so that the duct causes an outward fanning or lateral divergence of the outlet flow. This serves to get the flow farther back and more evenly distributed within the compartment. 
         [0038]    The exemplary duct  100  ( FIG. 3 ) comprises a mounting flange  110  at the inlet  102  and a duct body  112  extending downstream therefrom to the outlet. The exemplary flange has a perimeter array of mounting holes  114  for securing to the rear wall of the bay  52 .  FIG. 3  is a perspective view of the duct looking generally downward and rearward from the right front (right and front being viewed from the point of view of the vehicle).  FIG. 4  is a generally forward and downward view from the left rear.  FIG. 5  is a generally upward and forward view from the right rear. The duct body has an upper wall portion  120  ( FIG. 3 ) and a lower wall portion  122  ( FIG. 5 ) joined by respective left and right wall portions  124  and  126  ( FIG. 4 ). The exemplary duct has a proximal trunk portion  130  which extends downstream from the inlet  102  and flange  110  and branches off into a plurality of branches (e.g., four ultimate branches  132 A,  132 B,  132 C, and  132 D being shown from left-to-right). The branches are separated by walls  134 A,  134 B, and  134 C. At a downstream/rear edge  140  of the duct forming the outlet, the duct upper wall portion  120  includes a plurality of mounting tabs  142  each having an associated mounting hole  144  for receiving a screw to fasten the duct to the ceiling. 
         [0039]    The exemplary duct also includes a plurality of reinforcing structures including streamwise externally protruding ribs  150  and circumscribing transverse externally protruding ribs  152 . A rearmost of the ribs  152  at the downstream/rear edge  140  extends only along the lower wall portion  122  and left and right wall portions  126  but not along the upper wall portion. This allows a downstream region  156  of the upper surface of the upper wall portion to fit flat against the ceiling near the outlet. 
         [0040]      FIG. 7  shows an inlet width W I  and an inlet height H I .  FIG. 7  further shows a flange width W F  and flange height H F .  FIG. 6  shows an outlet width W O  and  FIG. 8  shows an outlet height H O . Due to the fanning and divergence, the exemplary W O  is at least 50% greater than W I  (e.g., 150%-300% of W I , more narrowly, 180%-250% or an exemplary about 200%). The outlet height H O  may be smaller than the inlet height H I  in approximately the same proportion to maintain flow cross-sectional area.  FIG. 8  further shows the amount of upward offsetting of the outlet relative to the inlet. A lower end of the inlet is at a height H 1  below the ceiling  70  and an upper end of inlet is at a height H 2  below the ceiling  70  whereas the upper end of the outlet is essentially at the ceiling. The exemplary center of the outlet is shifted upward relative to the center of the inlet by an amount H 3  which may exceed the outlet height and may exceed the inlet height. The exact offset will depend upon the particular refrigeration system being adapted. 
         [0041]    The exemplary duct extension  100  is formed by a twin-sheet vacuum thermo-forming process. In one such process, one sheet generally forms a lower half of the duct and another sheet generally forms an upper half. In an exemplary process, there is an upper mold and a lower mold. These have interior profiles complementary to upper and lower portions of the duct to be molded. An upper sheet and a lower sheet are placed into a space between the molds and may be contacted to the molds. The sheets are heated and drawn against the mold surfaces by vacuum applied through the molds. Thereafter, the molds are brought together to locally contact adjacent portions of the two formed sheets and thermally fuse them. The molded part may then be cooled to harden. The mold may be opened and the part ejected. There may be trimming of flash before and/or after mold separation and part ejection. 
         [0042]    The twin sheet vacuum thermoforming facilities a surprisingly robust yet lightweight and inexpensive configuration. For example, the exemplary walls  134 A- 134 C may be formed by deformations in one or both sheets. In this example, along a forward portion  180  of each wall and an aft portion  182 , the wall is formed by deformations of both sheets (the lower sheet protruding upward and the upper sheet protruding downward) so that, within the wall, the sheets are fused to form a transverse web at an intermediate height between adjacent portions of the two sheets and their respective associated upper and lower wall portions. In the exemplary embodiment, however, there is an interruption in the wall between the portions  180  and  182 . The exemplary interruption is formed by locally having the wall substantially entirely formed by deformation of the lower sheet so that the two sheets fuse at a location (small local region)  186  ( FIG. 4 ) locally coplanar with the upper wall. This location  186  is along the flat end portion  156  of the upper wall near a forward end thereof. This allows the locations  186  to provide further attachment points for fastening the duct to the ceiling. 
         [0043]    Turning to  FIG. 7 , it is seen that each wall extends from a leading edge  190  to a trailing edge  192  ( FIG. 4 ). Each wall includes a left side  192  and a right side  194 . These sides  192  and  194  can extend continuously across the portions or regions  180 ,  186 , and  182 . Viewed from the top in  FIG. 4 , the regions  180  and  182  are upwardly directed recesses while the region  186  is flat and unrecessed. Viewed, however, from the bottom in  FIGS. 5 and 6 , there is one continuous recess spanning all three regions/portions  180 ,  182 , and  186  with region  186  representing an upward deepening. At the regions  186 , the web of joined material may have a mounting hole  188  ( FIG. 4 ) to receive an additional screw. The screw may be inserted upwardly into the deepened area of the compartment and threaded into the ceiling. This provides a robust attachment of the duct while minimizing internal interruptions in flow or otherwise compromising the structural integrity provided by the walls. The walls provide structural integrity by maintaining spacing of the upper and lower wall portions. 
         [0044]    The use of “first”, “second”, and the like in the following claims is for differentiation only and does not necessarily indicate relative or absolute importance or temporal order. Where a measure is given in English units followed by a parenthetical containing SI or other units, the parenthetical&#39;s units are a conversion and should not imply a degree of precision not found in the English units. The same “upper” and “lower” orientations are used to describe the duct in its final condition and/or when being molded. This is not a requirement. 
         [0045]    One or more embodiments have been described. Nevertheless, it will be understood that various modifications may be made. For example, when applied to an existing basic system, details of such configuration or its associated use may influence details of particular implementations. Accordingly, other embodiments are within the scope of the following claims.