Patent Publication Number: US-2009217689-A1

Title: Integrated transport refrigeration unit with limited heat transfer and quick mount housing

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a transport refrigeration unit including a condenser located within a vehicle. More particularly, the invention relates to an apparatus and a method for quickly mounting a refrigeration unit to a vehicle and limiting the heat transfer between the refrigeration unit components and the vehicle interior. 
     Conventional transport refrigeration units provide cooling inside a vehicle compartment. The conventional transport refrigeration units are typically located on a vehicle roof within a refrigeration unit housing. The transport refrigeration unit cools air that is pumped into the vehicle compartment to provide cooling. 
     A condenser produces heat, and vents within the refrigeration unit housing allow for external airflow to reach the refrigeration unit components to manage the heat created by the condenser during operation. The vehicle roof acts as an insulator to protect the vehicle interior from the heat produced by the condenser. 
     Locating the refrigeration unit housing on the vehicle roof is unsightly. It would be desirable to locate the refrigeration unit within the vehicle compartment to hide the refrigeration unit components from external view. However, heat from the condenser and other components is emptied into the vehicle compartment, counteracting with the cooled air pumped into the vehicle compartment from the refrigeration unit. Also, moisture from the external environment and water that collects on the evaporator must be disposed of so that is will not leak from the refrigeration unit into the vehicle. Additionally, the refrigeration unit housing must be removable for maintenance and repair. 
     An arrangement and a method for locating refrigeration unit components in a vehicle while providing a removable housing and sealing from the vehicle interior is needed. 
     SUMMARY OF THE INVENTION 
     In the present invention, a vehicle roof supports a refrigeration unit. The refrigeration unit includes an external housing located primarily outside of the vehicle compartment and an internal housing located primarily inside of a vehicle compartment. The internal housing may have an inner wall spaced from an outer wall with air located between the walls to insulate the components of the refrigeration unit from the interior of the vehicle. 
     The external housing, a fan, and a fan cover may be assembled prior to assembly on the vehicle roof. Likewise, the internal housing, a condenser, a compressor, and an evaporator may be assembled together into a refrigeration unit chassis prior to assembly with the vehicle roof. Fasteners are used to assemble the internal housing to the chassis for easy removal. The fasteners have a locking portion which is inserted through a hole in the internal housing. 
     The external housing and the fan cover reduce the amount of water and other external contaminants that enter the refrigeration unit. A gasket may be located between the refrigeration unit and the vehicle roof for further sealing. Water drains are located at the bottom of the internal housing along the inner wall to collect any water within the refrigeration unit. The water drains lead to a water outlet that allows moisture from within the refrigeration unit to drain. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a schematic view of a vapor compression system of the present invention; 
         FIG. 2  shows a perspective view of a refrigeration unit of the present invention; 
         FIG. 3  illustrates a schematic side view from within the refrigeration unit; and 
         FIG. 4  is an exploded view of the components of the refrigeration unit. 
         FIG. 5   a  is a cross section of one embodiment of a fastener retaining an internal housing to a chassis of the present invention. 
         FIG. 5   b  is a bottom view of one embodiment of the internal housing of the refrigeration unit. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a vapor compression system  10 , such as a refrigeration system, including a compressor  12  that compresses a fluid, such as refrigerant. From the compressor  12 , the refrigerant is delivered downstream to a heat exchanger, such as a condenser  14 . In the condenser  14 , the refrigerant rejects heat to an external fluid medium. In the embodiment shown, the external fluid medium is air. From the condenser  14 , the refrigerant travels to an expansion device  16  and is expanded to a low pressure. The refrigerant accepts heat from another fluid medium, such as air, in an evaporator  18  and then flows to the compressor  12 , completing the cycle. 
       FIG. 2  shows a perspective view of a refrigeration unit  20  of the present invention including the vapor compression system  10 . A vehicle roof  22  supports the refrigeration unit  20 . The refrigeration unit  20  includes an external housing  24  and an internal housing  26 . The external housing  24  is located primarily outside of the vehicle roof  22 . The internal housing  26  is located primarily inside of a vehicle compartment  21  and under the vehicle roof  22 , as shown. External air enters the external housing  24  through a first opening  28  located between the vehicle roof  22  and the external housing  24 . As shown, the refrigeration unit  20  can include multiple first openings  28  to increase the airflow into the refrigeration unit  20 . The air passes over the components of the refrigeration unit  20 , such as the condenser  14  and the compressor  12  and is heated. The now heated air exits through a second opening  30  in the external housing  24 . A cover  32  may be located at the second opening  30  to reduce the amount of water and other external contaminants that may enter the refrigeration unit  20  through the second opening  30 . Additionally, the external housing  24  also assists in preventing water and other external contaminants from entering the refrigeration unit  20 . 
       FIG. 3  illustrates a schematic side view of the refrigeration unit  20 . External air, illustrated by arrows A, enters the refrigeration unit  20  through the first opening  28 . The external air flows past the components of the refrigeration unit  20 . Specifically, the air accepts heat from the refrigerant in the condenser  14  and passes over the compressor  12  prior to exiting the refrigeration unit  20  through the second opening  30 . The refrigerant cooled by the condenser  14  is expanded in the expansion device  16  and flows into an evaporator  18 , where the refrigerant cools air to be sent into the vehicle compartment  21 . The outside air accepts heat from both the condenser  14  and the compressor  12 , removing heat from the compressor  12  as a result of operation. The heated air exits the refrigeration unit  20  through the second opening  30  and flows outside the vehicle. 
     A fan  38  located proximate to the second opening  30  controls the airflow through the refrigeration unit  20 . A sensor  39  located within the refrigeration unit  20  measures the pressure and activates the fan  38  accordingly. As the sensor  39  senses a rise in the pressure of the air exiting the refrigeration unit  20  above a threshold, the fan  38  is activated. Likewise, when the sensor  39  senses a drop in the pressure of the air exiting the refrigeration unit  20  below a threshold, the fan  38  is deactivated. The cover  32  is attached to the external housing  24  proximate to the second opening  30  to cover the fan  38 . 
     The condenser  14  is located proximate to the first opening  28  and in the airflow path of the refrigeration unit  20 . Both the condenser  14  and the compressor  12  are primarily located within the internal housing  26  under the vehicle roof  22 . Additionally, the evaporator  18  may also be located within the internal housing  26 , as shown in  FIG. 4 . However, the evaporator  18  need not be located within the airflow path through the refrigeration unit  20 . 
     The internal housing  26  may have a inner wall  44  spaced from an outer wall  46 . The inner wall  44 , the outer wall  46  and the air located there between insulate the components of the refrigeration unit  20  from the interior of the vehicle. Additionally, a gasket  42  may be located between the refrigeration unit  20  and the vehicle roof  22  for further sealing between the refrigeration unit  20  and the vehicle compartment  21 . The gasket  42  may be integrated into grooves in the internal housing  26 . 
     Referring to  FIG. 4 , the external housing  24 , the fan  38 , and the cover  32  may be assembled prior to assembly on the vehicle roof  22 . The fan  38  is assembled within the second opening  30  in the external housing  24 . The cover  32  attaches to the external housing  24  to shield the second opening  30  and fan  38 . Likewise, the condenser  14 , the compressor  12 , and the evaporator  18  may be assembled together into a refrigeration unit chassis  48  prior to assembly with the vehicle roof  22 . Fasteners  50  are used to assemble the internal housing  26  to the chassis  48  for easy removal. By pre-assembling the components and providing fasteners  50 , handling and removal is facilitated if any maintenance is required. 
       FIG. 5   a  and  5   b  illustrate the fasteners  50 , which are quarter-turn locking fasteners, and have a locking portion  52  that is inserted through a hole  54  in the internal housing  26 . The locking portion  52  engages the chassis  48  to retain the internal housing  26  to the chassis  48 . The internal housing  26  has a recessed portion  53  to receive the fasteners  50  on the opposing side of the internal housing  26  that is seen by the vehicle compartment  21 . The fasteners  50  provide their own sealing on the locking portion  52  to eliminate any leaking from the refrigeration unit  20  to the vehicle compartment  21  through the insert holes  54  for the locking portion  52 . The locking portion  52  may be manufactured from a polyurethane material, or have a sealed disc manufactured from polyurethane material attached. In the embodiment shown, there are four fasteners  50 . Additionally, the interior wall  44  of the internal housing  26  may be coated in polyurethane material to aid in sealing. Other types of fasteners or locking devices may also be used. One skilled in the art would know the number and type of fasteners  50  to utilize in a specific application of the invention. 
     Referring back to  FIG. 4 , the cover  32  and the external housing  24  also assist in preventing water and other external contaminants from entering the refrigeration unit  20 . However, some moisture may still enter the refrigeration unit  20 . Also, moisture may collect on the components of the refrigeration unit  20  during operation. Water drains  56  are located at the bottom of the internal housing  26  within the inner wall  44 . In the embodiment shown, the water drains  56  are trenches formed in the internal housing  26 . Additionally, a drain receiver  59  may be located in the portion of the internal housing  26  that houses the evaporator  18 . The water drains  56  and drain receiver  59  may be lined with Mylar foil to limit air bypassing out of the internal housing  26 . The water drains  56  and drain receiver  59  lead to a water outlet  58 . The water outlet  58  allows moisture from within the refrigeration unit  20  to drain out. The water outlet  58  preferably leads to piping, such as polyvinyl chloride (PVC) pipes, leading to the vehicle exterior. In one embodiment, the water outlet  58  is a 40-millimeter pipe. 
     Brackets  60  may be manufactured from or coated in a polyurethane material and fixed to the chassis  48 . The brackets  60  may fit within inserts  62  in the internal housing  26  to allow any tubing and packaging to reach the refrigeration unit  20 . Additionally, the brackets  60  assist in insulating the high-pressure side of internal housing  26  including the compressor  12  and the condenser  14  from the bottom pressure side of the internal housing  26  where the evaporator  18  is located. The brackets  60  also insulate the high-pressure side of the internal housing  26  from the vehicle compartment  21  when the unit is assembled. 
     The external housing  24 , the fan  38 , and the cover  32  are assembled together and mounted to the exterior side of the vehicle compartment  21 . The compressor  12 , the condenser  14 , and the evaporator  18  are assembled into the chassis  48 . The chassis  48  is then mounted to the interior side of the vehicle compartment  21  to align with the external housing  24  mounted on the exterior side. Drainage pipes are attached to the water outlet  58 , and the gasket  42  is assembled onto the internal housing  26 . The internal housing  26  is then attached to the chassis  48  using the fasteners  50 . 
     Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.