Patent Publication Number: US-2015059389-A1

Title: System and apparatus for heating or cooling having fluid cooled electronics

Description:
PRIORITY 
     The present application claims priority to U.S. Provisional Patent Application No. 61/874,147, filed Sep. 5, 2013 and to U.S. Provisional Patent Application No. 61/874,867, filed Sep. 6, 2013, the disclosures of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to fluid cooled power electronics in systems such as those for heating or cooling, and more particularly, but not exclusively, to active fluid cooling of power electronics in a heating or cooling system such as an outdoor refrigeration unit. 
     BACKGROUND 
     Providing enhanced cooling capabilities to power electronics in heating, ventilation, and air conditioning (HVAC) systems remains an area of interest. Some existing systems have various shortcomings relative to certain applications. For instance, while air cooling has long been an industry standard, air cooling can be ineffective as applied to high power or otherwise highly heat productive systems. Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY 
     One embodiment of the present invention is an assembly having a replaceable high temperature power electronics cooled by a refrigerant where a coolant line for the refrigerant need not be disassembled to service the power electronics. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for maintaining a conduit used to cool power electronics substantially in place when the power electronics are serviced. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates one embodiment of a system for heating or cooling; 
         FIG. 2  illustrates one embodiment of a power electronics control box suitable for use in the system of  FIG. 1 ; 
         FIG. 3  illustrates a different view of the power electronics control box and part of the system of  FIG. 1 ; 
         FIG. 4  illustrates yet a different view of the power electronics control box and part of the system; 
         FIG. 5  illustrates yet a different view of the power electronics control box, including control box layout features according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     With reference to  FIG. 1 , one embodiment of a system  100  for heating or cooling a conditioned space such as a building interior includes an outdoor refrigeration unit  50 . An external refrigerant coil such as an evaporator coil, blower, and such other components of system  100  as might be used in system  100  apart from unit  50  are well known and thus not depicted in  FIG. 1 . Unit  50  is illustrated having an outer housing  52  that includes a number of vent openings  54  structured to admit a flow of air between an interior and exterior of outdoor refrigeration unit  50 . Unit  50  depicted in the illustrated embodiment includes a fan  56  rotatable about a vertical axis  106  and structured to draw air through openings  54  so as to generate the flow of air into an interior of unit  50  to assist in cooling refrigerant as will be described further below. As used herein, an outdoor refrigeration unit includes devices such as air conditioners and heat pumps as it will be appreciated that heat pumps can be operated as air conditioners. 
     Outdoor refrigeration unit  50  can take on many forms, and in the illustrated embodiment is depicted as a split air conditioning unit in which unit  50  houses a compressor  58  structured to elevate a pressure of the cooling refrigerant and condenser  60  structured to extract heat from the cooling refrigerant. Compressor  58  includes an electric compressor motor  59 . Condenser  60  may include a refrigerant coil  63 , within housing  52 , for conveying the refrigerant fluid so as to exchange heat with the flow of air, and is in fluid communication with compressor  58 . Although unit  50  can be a split system as discussed above, unit  50  can also include a full system having all traditional refrigeration components such as might be included in a window air conditioning unit. 
     Compressor  58  is in fluid communication with condenser  60  through a refrigerant conduit  62 . In a practical implementation strategy, conduit  62  may be in fluid communication with at least one of refrigerant coil  63  and compressor  58 . Conduit  62  can be made of a variety of materials and have a variety of cross sectional shapes. Conduit  62  is formed of copper in a practical implementation strategy. Unless discussed to the contrary, the term “conduit” can include singular or multiple passageways that together form a flow path for the cooling refrigerant. Conduit  62  can be found between components such as compressor  58  and condenser  60 , and in some forms can also extend to locations/components beyond either of compressor  58  and/or condenser  60 . In such an example where multiple instances of conduit  62  are found between different components of a refrigeration system that together form a pathway, the conduit can be referred to as a conduit system. Some split air conditioning systems when installed can include a conduit system that provides for a refrigerant outlet and a refrigerant inlet to unit  50 . In such an example, the refrigerant outlet can convey cooling refrigerant to an evaporator located outside of unit  50 . Such an evaporator can be located in an interior room of a building such as a house or business where an expansion valve or other useful device can create a rapid pressure and temperature loss of the cooling refrigerant to cool the interior room. When a split air conditioning unit  50  is installed and connected to an evaporator located in an interior of a building, the conduit system can generally refer to a closed path of conduit that is used to circulate cooling refrigerant between all components of a working refrigeration system. 
     Compressor  58  can be driven by electric motor  59 , which can be a variable speed motor. In one form the variable speed motor is a DC motor that can be of the brushless kind, but other kinds are also contemplated. The variable speed motor can be coupled with a power electronics unit or DC drive  64  to provide necessary power management, such as through switching, to provide an adequate source of power to motor  59 . Unless stated to the contrary, the terms “power electronics” and “power electronics unit” are intended to cover DC drives, and any mention of power electronics herein will not be construed such that it does not cover DC drives. In one embodiment power electronics unit  64  can include one or more transistors, such as IGBT&#39;s, that provide the necessary power to operate the motor at variable speeds. During operation the power electronics can become very warm and a source of cooling can be provided via heat transfer between the DC drive  64  and cooling refrigerant passing through conduit  62 . The conduit  62  can be placed in thermal contact directly or through an intermediary with the drive  64 . 
     The power electronics or DC drive can be accessible via an external door provided in an outer housing of the unit  50  for servicing and/or maintenance. The external door can be a panel or other like device that can be affixed to the air conditioning unit such as through a hinge mechanism, rails, slotted attachments, screws, bolts, etc. In some forms the power electronics can be located in a control box internal to the unit  50  but otherwise accessible via the external door discussed above. It can be noted that part of housing  52  is free of vent openings generally in the vicinity of power electronics unit  64 . While such a feature might or might not be evident in a commercial embodiment, the absence of openings is presented to illustrate the nature of air flow and lack of air flow through a first internal space  102  in housing  52 , and a second internal space  104 , respectively. In a practical implementation strategy, refrigerant coil  63  and compressor  58  are positioned within first internal space  102 , and power electronics unit  64  is positioned within second internal space  104 . Compressor  58  can also be located in a compartment separate from a high rate flow path associated with the fan  56  and condenser  60 . A through space, not specifically illustrated in  FIG. 1 , extends between first interval space  102  and interval space  104 , the significance of which will be apparent from the following description. 
     Turning now also to  FIG. 2 , there is shown one embodiment of an interior portion of unit  50  in which is disposed power electronics unit  64 . Though only a portion of the interior is shown in  FIG. 2 , space  104  may be located in a corner of housing  52  of outdoor refrigeration unit  50 . Walls  66  and  68  form two sides of the control box, with the remaining sides being formed by housing  52 . Walls  66  and  68  each include a flange with fastener openings shaped to abut a corner of housing  52 . In some forms walls  66  and  68  are one continuous wall. The walls  66  and  68  are coupled to an outer housing of the unit  50  to form an enclosure that can be referred to as a control box  53 . Control box  53  can be set apart from high air flow rate paths associated with fan  56  and condenser  60  such that relatively little to no cooling air is circulated within control box  53 . 
     Inside control box  53 , conduit  62  is routed to deliver a flow of cooling refrigerant into control box  53  such that it is placed in thermal contact with power electronics  64 . Thereafter conduit  62  is routed to deliver the flow of cooling refrigerant out of control box  53 . Conduit  62  is routed through a cutout or through space  70  in wall  66  in which is located a securing device  71  that fits in cutout  70  to capture conduit  62 . It can be seen that conduit  62  extends from first internal space  102  into and out of second internal space  104  via cutout  70 . Cutout  70  can be located such that it extends to the end of wall  66 , but different embodiments can locate cutout  70  elsewhere. Conduit  62  can deliver refrigerant fluid into control box  53  from any component of outdoor refrigeration unit  50 , and can discharge the refrigerant fluid to any other component. For example, conduit  62  can receive refrigerant fluid from a compressor and deliver to a condenser; conduit  62  can receive refrigerant from a condenser and deliver to an evaporator; conduit  62  can receive refrigerant from the evaporator and deliver to the compressor. Any other variation of routing is also contemplated, including routing only a portion of the refrigerant fluid to control box  53  relative to a total refrigerant mass flow. 
     Securing device  71  can be used to provide support and/or positively secure conduit  62  to wall  66 , as well as attenuating vibrations. From compression  58 , or as experienced during shipping. In one embodiment securing device  71  takes the form of a grommet that fills cutout  70  and captures conduit  62 , but other methods of securing conduit  62  can also be used. The grommet can be a single piece or it can take the form of multiple pieces. For example, separate grommet halves can be used to sandwich wall  66  therebetween and secure and/or support conduit  62 . Device  71  can be formed of natural rubber, or other rubber-like materials. In one embodiment, device  71  is formed of EPDM. In  FIG. 4 , a minor lobe  77  of the grommet/device  71  is shown positioned upon a first side of wall  66 , whereas a larger major lobe  79  is shown positioned upon a second side of wall  66 , within space  104 . A groove  81  receives edges of wall  66  forming cutout  70 . Additional and/or alternative techniques such as packing, screws, clips, etc can also be used to secure conduit  62  to one or both of the walls  66  and  68 . Although the grommet fits into a single cutout in wall  66  to pass two separate conduit portions, some embodiments can include two cutouts having two securing devices such that a single conduit is passed through each cutout and secured to the wall(s) through the two securing devices. 
     Referring also to  FIGS. 3 and 4 , there are shown additional views in which a supply segment  65 , a return segment  67 , and a cooling segment  69  of conduit  62  are labeled. The terms “supply” and “return” are chosen as a matter of convenience, and either segment of conduit  62  could be used to deliver refrigerant fluid or return refrigerant fluid to and from control box  53 . It can be noted that each of supply, return, and cooling segments  65 ,  67 , and  69  are tubular in form, and segments  65  and  67  each extend through through space  70 . Conduit  62  may be monotubular such that a single uniformly shaped and uninterrupted fluid passage extends into and out of internal space  104 . Cooling segment  69  may have a U-shape, and may be vertically oriented generally in parallel with axis  106  shown in  FIG. 1 . In a practical implementation strategy, cooling segment  69  may be sized and positioned such that hot spots in unit  64 , for instance corresponding to IGBT locations, are generally aligned with or at least overlapped by the straight vertical runs of conduit  62  that form the legs of the U-shape in cooling segment  69 . 
     Conduit  62  is attached to a heat sink  72  which can be made of a variety of materials and is used to aid in heat transfer between power electronics unit  64  and cooling refrigerant fluid conveyed through conduit  62 . Such a cooling aid can be used to cool high temperature components associated with the power electronics such as IGBT&#39;s and copper coils. Heat sink  72  can include an internal passageway for the conduit  62  which can be formed in some embodiments by two separate heat sink halves that sandwich the conduit  62 . In some forms heat sink  72  is a cover plate that captures conduit  62  between it and the power electronics. Heat sink  72  can be an aluminum plate in some embodiments, but other shapes and materials are contemplated herein. 
     Heat sink  72  is releaseably attached to power electronics  64  via fasteners  74  such that conduit  62  need not be disassembled when servicing power electronics  64 . In some embodiments conduit  62  and/or heat sink  72  need not be moved, or need be moved an insubstantial amount when power electronics  64  is serviced such that conduit  62  need not be disassembled (nor refrigerant drained) to remove the electronics. Fasteners  74  can take a variety of forms and can have any number that are used. Three fasteners  74  in a regular vertical spacing, and equally torqued, provides a practical implementation strategy. In some embodiments the fasteners are screws or bolts, but other embodiments can include clips, slotted attachments, rails, etc and combinations thereof. It will be appreciated that heat sink  72  and fasteners  74  form a clamping mechanism  75  coupling conduit  62  to power electronics unit  64 . Clamping mechanism  75  has a clamped state holding cooling segment  62  against power electronics unit  64  so as to maintain the thermal contact, and a release state where power electronics unit  64  can be decoupled from conduit  62 . Fasteners  74  can be engaged and disengaged to switch clamping mechanism  75  between the clamped state and the release state. 
     With continued reference to  FIGS. 1-4 , but also now to  FIG. 5 , the present disclosure further contemplates a combination of unique features relating to layout of control box  53 , including an arrangement of various components in space, integration of separate components into one, and design for manufacture and assembly. Among other things, such features are together contemplated to hasten and simplify assembly and reduce risk of mistakes in assembly, reduce electromagnetic interference (EMI), and optimize heat transfer out of control box  53  according to the cooling techniques set forth herein. 
     Current high seasonal energy efficiency ratio (SEER) products as used in outdoor compressors for heating ventilation and cooling systems typically have multiple circuit boards and external components (e.g., capacitor, relay, transformers, etc.) mounted in the control panel area with high and low voltage AC as well as low voltage DC wiring comingling in a confined space. Mounting individual components and circuit boards to the control panel with intertwined wires causes EMI, risk of miswiring, control board resetting issues, and reliability problems. There is also high takt time and labor costs associated with assembling individual components and the necessary wiring to the panel. It also reduces the number of connections necessary at run test. Warranty and field costs increase as a result of the issues listed above. 
     In control box  53  according to the present disclosure, poka-yoke electrical connections (not numbered) are used throughout, as is shielded harness for compressor wiring  94  to eliminate EMI noise. A communication display assembly  90  is also provided for field trouble shooting, and high voltage wires  94  versus low voltage wires  96  are routed separately for better controls reliability. A PFC choke  92  is integrated onto power electronics unit  64 , and mounted and supported upon a housing  59  thereof. Also shown in  FIG. 5  is a U-shaped groove  80  formed in housing  59 , where it can be seen that conduit  62 , and in particular cooling segment  69 , is within groove  80 . Heat sink plate  72  has a first groove  83  and a second groove  85  therein, with portions of conduit  62  forming legs of U-shaped cooling segment  69  being positioned within first and second grooves  83  and  85 . In  FIG. 5 , heat sink plate  72  is shown in cutaway to illustrate certain of these features. When unit  50  is completely assembled for service, control box  53  may be completely sealed and meets agency requirements including rain tests. 
     As alluded to above, certain known control box arrangements employ multiple components and multiple circuit boards. In control box  53 , the multiple circuit boards have all been included in the design of the integrated inverter drive/power electronics unit  64 . A circuit board  96  is visible in  FIG. 5 , and may be one of three circuit boards or potentially a still greater number all positioned within unit  64 . This eliminates the need for excessive wire routings throughout the control box and reduces opportunities for miswiring. Power electronics unit  64  is easy to replace and assemble, as discussed herein, and can now have one SKU instead of multiple SKU&#39;s for multiple components. 
     As also noted above, in order to eliminate EMI issues the high and low voltage AC and DC wires are separated through several approaches. Previous control box designs made little attempt at separating low and high voltage wiring. Sensors have been found to report incorrect data due to EMI issues, however. According to the present disclosure, in control box  53  the layout is such that high voltage wires  94  enter at the bottom, or a lower location, and low voltage wires  96  enter through a slot in the top of the box, such as a higher location near the top of wall  66 . The ability to separate low voltage sensors from high voltage wires eliminates the need to spend additional money on shielded sensor wires. In order to minimize voltage drop and EMI noise, the compressor harness is optimized to be as short as possible. The communications display assembly (“CDA”)  90  is a substitution for the typical LED light configuration on or in association with unit  64  that helps a technician determine the health of the system, and may be located at the top of control box  53  approximately as shown so that it is easily accessible and removable. As discussed above, the drive (unit  64 ) is cooled by routing the liquid tubing (conduit  62 ) into control box  53  and clamping it to the drive. This allows the drive to be easily removed from control box  53  for servicing or replacement. Wire lengths are optimized so as to prevent excessive wire bundling inside of the box, and are routed directly to their terminations. All connectors in the box are poka-yoke so as to prevent miswiring as noted above. Yet another feature relates to routing of the low voltage wires out of control box  53 . In a practical implementation strategy, low voltage wires  96  gain entry/exit via a slot shaped in such a way that the low voltage wires are captured and there is no longer a potential for them to be pinched between control box  53  and a top of housing  52  of unit  50 , or otherwise pinched between components. Also in a practical implementation strategy, the only electronic components in the control box are the integrated inverter drive/unit  64  and communications display assembly  90 . 
     It can further be noted that in order to eliminate EMI issues, the high and low voltage wires are separated through several means. The layout of control box  53  was designed so that the high voltage wires enter through the bottom and the low voltage wires enter through a slot in the top of the box so that they co-mingle as little as possible. The DC and AC wires must also be separated, so the high voltage AC input wires enter the control box through a sheet metal barrier that separate them from the DC output wires coming from the drive. The high voltage AC wires then travel to the top of the box through a channel that exists between the drive enclosure and control panel. Since the channel is made of metal on all sides, this provides a shield so that the electromagnetic emissions from the high voltage wires are contained. The low voltage sensors coming from a different part of the system travel up the back side of the control panel so as not to have interference from the high voltage AC wires. The ability to separate the low voltage sensors from the high voltage wires eliminates the need to spend additional money on shielded sensor wires. The compressor harness may be optimized to be as short as possible in order to minimize voltage drop and EMI noise. In order to maintain that short length, it is routed through the bottom of the box instead of over the top as is usually done. 
     The communications display assembly (CDA) is located at the top of the control box so that it is easier for a technician to stand and diagnose the system. Through the use of captive screws and locking features on tabs it can easily be removed. It also has extra wire length so that a technician can hold it in his/her hands while using it. The CDA is also in the low voltage section of the control box so that a technician does not have to place his hands near dangerous high voltage wires. 
     The low voltage wire entry slot is shaped like an upside down light bulb so that the wires can slip through individually, but when they are wire tied together the narrow opening prevents them from popping out. This eliminates the potential for wires getting pinched between the box and the top cover. 
     It is appreciated that integrated drives may be utilized to reduce the number of components located in control boxes. Further, the high voltage and low voltage wires may be separated between the left and right sides of the box instead of the top and bottom portions. Moreover, air cooled heat sinks could be utilized instead of liquid cooling. In addition, the embodiments disclosed herein could be incorporated in residential or commercial HVAC units, or variable speed air compressors. 
     Though the description herein is written from the perspective of a refrigeration unit, it will be appreciated that the techniques described herein are also applicable to other devices such as air compressors, hydronics, automobiles, power electronics, and high power LED&#39;s. While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred or practical utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.