Patent Publication Number: US-2023164959-A1

Title: Heat sink for power electronics devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 63/282,288 filed Nov. 23, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Exemplary embodiments pertain to the power electronics such as in a coil unit, and more particularly, to a heat sink for cooling power electronics that are mounted within a coil unit. 
     Power electronic devices such as motor drives can generate waste heat during operation based on the efficiency of the device. Additionally, when the power electronic devices heat up, their efficiency can degrade adding to the amount of heat they generate. Accordingly, there is a need to maintain these power electronic devices within suitable operating levels. 
     BRIEF DESCRIPTION 
     In an embodiment, a heat sink for cooling at least one power electronics device in a coil unit includes a base plate having a first surface and a plurality of fins extending from the first surface. A height of the plurality of fins measured perpendicular to the first surface varies across a width of the base plate. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the base plate includes a central portion and at least one end portion and the plurality of fins includes a first plurality of fins extending from the central portion and a second plurality of fins extending from the at least one end portion. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments a configuration of the first plurality of fins varies from a configuration of the second plurality of fins. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the height of the first plurality of fins varies to form a curvature. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the height of the second plurality of fins varies to form the curvature. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the curvature is uniform. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the curvature is non-uniform. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the plurality of fins extends over a substantially entire length of the base plate. 
     In an embodiment, a coil unit includes a heat exchanger, a fan assembly mounted to the heat exchanger, at least one power electronic device, and a heat sink mounted adjacent to the at least one power electronic device. The fan assembly is operable to move an airflow through the heat exchanger and across the heat sink. The heat sink includes a base plate having a portion vertically aligned with the fan assembly. A plurality of fins extend from the portion of the base plate. A height of the plurality of fins measured perpendicular to the base plate varies across a width of the base plate. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments a gap is defined between the plurality of fins arranged within the first portion of the base plate and the fan assembly. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the gap is uniform over the width of the base plate. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the gap varies over the width of the base plate. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the gap is at least about 5 mm. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the plurality of fins further comprises a first plurality of fins and a second plurality of fins. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the base plate includes a central portion and at least one end portion, the first plurality of fins being arranged at the central portion and the second plurality of fins being arranged at the at least one end portion. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the base plate has another portion, the another portion being disposed vertically beneath the portion vertically aligned with the fan assembly and further comprising another plurality of fins arranged at the another portion. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments a configuration of the plurality of fins is different than a configuration of the another plurality of fins. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments a height of the another plurality of fins varies to form an angled surface. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments the heat sink is symmetrical. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    is a side view of an example of a coil unit of a heating, ventilation, and air conditioning (HVAC) system according to an embodiment; 
         FIG.  2    is a side view of a heat sink and a portion of a fan assembly of a coil unit according to an embodiment; 
         FIG.  3 A  is a plan view of a portion of the fan assembly and a heat sink according to an embodiment; 
         FIG.  3 B  is a plan view of the heat sink of  FIG.  3 A  according to an embodiment; 
         FIG.  3 C  is an enlarged plan view of the heat sink of  FIG.  3 A  positioned relative to an outer edge of a fan blade according to an embodiment; 
         FIG.  4    is a perspective view of a heat sink according to another embodiment; 
         FIGS.  5 A- 5 D  are diagrams illustrating various configurations of a heat sink according to an embodiment; 
         FIG.  6 A  is a perspective view of the fan assembly and a heat sink of a coil unit according to an embodiment; 
         FIG.  6 B  is a plan view of a portion of the fan assembly and the heat sink of  FIG.  6 A  according to an embodiment; 
         FIG.  6 C  is a perspective view of the heat sink of  FIG.  6 A  according to an embodiment; 
         FIG.  6 D  is a perspective view of the heat sink of  FIGS.  6 A- 6 C  according to an embodiment; 
         FIG.  7    is a perspective view of a heat sink according to another embodiment; 
         FIG.  8 A  is a perspective view of a heat sink according to another embodiment; and 
         FIG.  8 B  is a rear perspective view of a heat sink according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     With reference now to  FIG.  1   , an example of an outdoor unit or coil unit  20  of a heating, ventilation, and air conditioning (HVAC) system is illustrated. The coil unit  20  includes a heat exchanger  22  and a compressor  24  fluidly coupled to the heat exchanger  22  and configured to pump refrigerant through the HVAC system. In the illustrated, non-limiting embodiment, the compressor  24  is positioned within the interior of the heat exchanger  22 ; however, embodiments having a compressor  24  arranged at another location are also contemplated herein. Further, the planform of the heat exchanger  22  may be any suitable shape, including but not limited to square, rectangular, circular, or another shape. The coil unit  20  may include a floor pan or base pan  26  configured to receive the heat exchanger  22  and maintain the heat exchanger  22  at a desired position. Arranged generally adjacent to a surface of the heat exchanger  22  is a fan assembly  28  configured to draw ambient air radially inward, through the heat exchanger  22  after which the heated air A is discharged upwardly through an opening (not shown). 
     In the illustrated, non-limiting embodiment, the compressor  24  is a variable speed compression device having a variable speed motor driven by a variable frequency drive (VFD). The one or more power electronic devices  30  that form the variable frequency drive may be mounted within the coil unit  20 , such as between two adjacent ends of the heat exchanger  22 . 
     Because the at least one power electronic device  30  generates waste heat during operation, the coil unit  20  includes a heat sink  32  configured to remove heat from the power electronic devices  30 . In an embodiment, the airflow A being driven through the coil unit  20  by the fan assembly  28  is used as a cooling fluid to remove heat from the power electronic devices  30  via the heat sink  32 . However, it should be understood that the heat sink  32  as described herein may be used in combination with other means for cooling the power electronic devices  30 , such as a refrigerant heat exchanger for example. 
     In the various embodiments of the heat sink  32  illustrated herein, the heat sink  32  includes a base plate  34  and a plurality of fins  36  extending from one or more portions of the base plate  34 . The base plate  34  is formed from a thermally conductive material and is mounted at an interior of the coil unit  20 , in axial alignment with at least a portion of the power electronics devices  30 . The base plate  34  may be made from a single material. However, embodiments where the base plate  34  includes a plurality of different materials are also contemplated herein. For example, as best shown in  FIG.  8 B , the base plate  34  includes a plurality of layers  35   a ,  35   b  of different materials. In an embodiment, the material of the layer  35   a  of the base plate  34  configured to mount and receive heat from the power electronic devices  30  has a higher thermal conductivity than the remainder of the layers of the base plate. In an embodiment, the layer  35   a  of the base plate  34  configured to mount and receive heat from the power electronic devices  30  is a copper material. 
     In an embodiment, all or at least a portion of the base plate  34  is also in vertical alignment, for example within the same horizontal plane, with a portion of the rotatable blades  38  of the fan assembly  28 . Further, the base plate  34  may be elongated in length such that when installed relative to the coil unit  20 , a first portion  40  of the base plate  34  is arranged horizontally adjacent to the fan blades  38  and a second portion  42  of the base plate  34  is disposed vertically below the fan blades  38  (see  FIG.  2   ). 
     In the illustrated, non-limiting embodiment, best shown in  FIGS.  3 A- 3 C,  4 , and  5   , the base plate  34  has a non-planar configuration. As shown, the base plate  34  is substantially symmetrical and includes a central portion  44  and at least one end portion  46 , such as two end portions  46  arranged at opposite sides of the central portion  44 . The end portions  46  may be offset from the plane of the central portion  44 . In such embodiments, the end portions  46  may be defined via a first and second bend formed in the base plate  34 . However, it should be understood that embodiments where at least a portion of the base plate  34  has another configuration, such as a substantially planar configuration (see  FIGS.  6 A- 6 D ), are also within the scope of the disclosure. 
     The plurality of fins  36  extends from one or more surfaces of the base plate  34 , such as from the first portion  40  and/or the second portion  42  at a first surface, toward an interior of the coil unit  20 . Although the plurality of fins  36  is shown extending substantially perpendicularly from the base plate  34 , embodiments where one or more of the fins  36  extends at another angle are also contemplated herein. The fins  36  may extend across the entire width or only a portion of the width of the base plate  34 . In an embodiment, the plurality of fins  36  is located at only the central portion  44  of the base plate  34  (see  FIGS.  4 ,  5 A,  5 B, and  5 D ). However, in other embodiments, a first plurality of fins  36   a  is located at the central portion  44  of the base plate  34  and a second plurality of fins  36   b  is located at one or both of the end portions  46  of the base plate  34 . 
     The configuration of the plurality of fins  36  may be substantially identical. Accordingly, in instances where the heat sink  32  includes a plurality of first fins  36   a  and a plurality of second fins  36   b , the configuration of each of the first plurality of fins  36   a  is identical to each of the second plurality of fins  36   b . However, in other embodiments, the configuration of the second plurality of fins  36   b  differs from the configuration of the first plurality of fins  36   a . Further, the configuration of each fin within the first plurality of fins  36   a  and/or the second plurality of fins  36   b  may be substantially identical, or may vary. For example, in an embodiment best shown in  FIGS.  3 A- 3 C , the first plurality of fins  36   a  arranged at the central portion  44  of the base plate  34  vary in height, measured perpendicular to the surface of the base plate  34 . For example, the height of the fins  36   a  may gradually increase (uniformly or non-uniformly) from the center of the central portion  44  of the base plate  34  toward the end portions  46  thereof. 
     Because the plurality of fins  36   a  and/or  36   b  are positioned radially outward of the fan blades  38  (see  FIG.  3 A ), the height of the fins  36   a  and/or  36   b  may vary across the width of the base plate  34  to achieve a general curvature (viewed via a plan view), such as a curvature similar to the periphery of the adjacent fan blades  38 . For example, in one of the non-limiting embodiments illustrated in  FIG.  5   , the heat sink  32  only includes a first plurality of fins  36   a  mounted at the central portion  44  of the base plate  34  and the height of the fins  36   a  varies to form a curvature. In another embodiment illustrated in  FIGS.  3 A- 3 C and  5 C , the base plate  34  includes a first plurality of fins  36   a  at the central portion  44  and a second plurality of fins  36   b  at the end portions  46 , and the first and second plurality of fins  36   a ,  36   b  cooperate to define a curvature. However, embodiments where the curvature is only defined by varying either the first plurality of fins  36   a  or the second plurality of fins  36   b , but not both, is also contemplated herein. 
     In an embodiment, the height of the fins  36   a  and/or  36   b  is selected to maintain a constant radius defined by the fins, or alternatively, to maintain a constant gap between the fan blades  38  and the fins  36   a  and/or  36   b . However, in an embodiment, the gap measured parallel to the height of the fins  36   a  and/or  36   b  may vary over the width of the base plate  34 . For example, the gap between the first plurality of fins  36   a  arranged at the middle of the central portion  44  of the base plate  34  and the fan blades  38  may be less than the gap between the first plurality of fins  36   a  closest to the end portions  46  or the second plurality of fins  36   b  at the end portions  46  of the base plate  34  and the fan blades  38 . Regardless of whether the gap is constant or variable, a minimum gap between the fan blades  38  and the fins  36   a  and/or  36   b  is at least about 5 mm and in some embodiments, the gap between the fins  36   a  and/or  36   b  and the fan blades  38  may range from about 5 mm to about 10 mm, or from about 5 mm to about 12 mm. 
     In another embodiment, regardless of the configuration of the base plate  34 , the height of the fins  36   a  and/or  36   b  may gradually increase from the end portion  46  of the base plate  34  towards the central portion  44  of the base plate  34 . For example, in the non-limiting embodiment, of  FIGS.  6 A- 6 D , the base plate  34  includes a first plurality of fins  36   a  and a second plurality of fins  36   b , and the height of the fins  36   b  located at each end portion  46  of the base plate  34  is shorter than the height of the fins  36   a  arranged at the center  44  of the base plate  34 . As shown, the height of the outermost fins  36   b  may taper from the maximum to the minimum such that in a plan view, the fins  36   a  and  36   b  appear to have at least one angled surface. In the illustrated, non-limiting embodiment, the height of the fins  36   b  varies such that the fins form a symmetrical trapezoid (see  FIG.  6 D ). 
     The first and/or the second plurality of fins  36   a ,  36   b  may be configured to extend over the substantial entirety, or alternatively, over only a portion of a length of the base plate  34 . In the illustrated, non-limiting embodiment, best shown in  FIGS.  2 - 5   , the first and/or second plurality of fins  36   a  and/or  36   b  extends over the substantially entire length of the base plate  34 , measured parallel to the fan axis X. In such embodiments, the base plate  34 , may but need not include the second portion  42  disposed vertically below the fan blades  38 . In another embodiment, the first and/or second plurality of fins  36   a ,  36   b  extends over only a portion of the length of the base plate  34 , such as over only the first portion  40  of the base plate  34  aligned with the plurality of fan blades  38 , or alternatively, over only the second portion  42  of the base plate  34  arranged vertically below the fan blades  38  (see  FIGS.  6 A- 6 D ). 
     Further, with reference now to  FIG.  7   , in an embodiment, the first portion  40  of the base plate  34  aligned with the fan blades  38  may have a first plurality of fins  36   a  arranged at the central portion  44  and a second plurality of fins  36   b  arranged at the ends  46  of the first portion  40  of the base plate  34  as previous described herein. In an embodiment, the second portion  42  of the base plate  34  located underneath the fan blades  38  includes a third plurality of fins  36   c . The third plurality of fins  36   c  may extend over the entire width, or alternatively, over only a portion of the width of the base plate  34 . In other embodiments, best shown in  FIGS.  8 A and  8 B , the first portion  40  of the base plate  34  may have only the first plurality of fins  36   a  arranged at the central portion  44 , or alternatively, only the second plurality of fins  36   b  arranged at at least one end portion  46 , while the second portion  42  of the base plate  34  located underneath the fan blades  38  includes the third plurality of fins  36   c.    
     In embodiments where the heat sink  32  includes fins  36  within both the first portion  40  and the second portion  42  of the base plate  34 , a fin within the second portion  42  may be vertically aligned with an adjacent fins of the first portion  40  to define an uninterrupted fluid flow path extending over an entire length of the base plate  34 . However, embodiments where vertically stacked fins  36  are offset from one another are also within the scope of the disclosure. 
     The configuration of the base plate  34 , the first plurality of fins  36   a , the second plurality of fins  36   b , and/or the third plurality of fins  36   c  may vary based on the loading of the HVAC system as well as the adjacent components within the coil unit  20 . For example, in the illustrated, non-limiting embodiment of  FIG.  7   , the fin height of the first plurality of fins  36   a  and the second plurality of fins  36   b  varies to forms a curvature when viewed in plan form. However, in the embodiments of  FIGS.  8 A and  8 B , the first plurality of fins  36   a  has a substantially uniform height. Because the third plurality of fins  36   c , is positioned underneath the fan assembly  28 , in an embodiment, the maximum fin height of the third plurality of fins  36   c  is substantially greater than a maximum fin height of the first plurality of fins  36   a , and in some embodiments, than the second plurality of fins  36   b . In the illustrated, non-limiting embodiment, the fin height of the third plurality of fins  36   c  increases from the edge portions  46  of the base plate  34  toward the central portion  44  to form a contour having angled sides when viewed in plan form. However, it should be understood that a heat sink  32  having any suitable fin configuration that does not interfere with the adjacent components of the coil unit  20  are within the scope of the disclosure. 
     As the fan blades  38  rotate about the fan axis, the airflow A moved by the fan assembly  28  moves over and through the plurality of fins  36  of the base plate, thereby removing heat from the fins  36  and the base plate  46  of the heat sink  32  and cooling the at least one power electronics device  30 . A coil unit  20  having a heat sink  32  as illustrated and described herein will enhance the heat transfer from the power electronic devices  30 , thereby increasing the efficiency of the coil unit  20 . 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.