HEAT SINK FOR POWER ELECTRONICS DEVICES

A heat sink for cooling at least one power electronics device in a coil unit includes a base plate having a first portion and a second portion. The second portion is arranged vertically beneath the first portion. A plurality of fins extends from a surface of the base plate. The plurality of fins is located at the second portion of the base plate. A height of the plurality of fins measured perpendicular to the surface varies across a width of the base plate.

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 portion and a second portion. The second portion is arranged vertically beneath the first portion. A plurality of fins extends from a surface of the base plate. The plurality of fins is located at the second portion of the base plate. A height of the plurality of fins measured perpendicular to the 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 a height of the plurality of fins at the central portion is different than a height of the plurality of fins 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 height of the plurality of fins at the central portion is greater than the height of the plurality of fins 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 height of the plurality of fins the at least one end portion varies such that the fins at the end portion have a taper.

In addition to one or more of the features described herein, or as an alternative, further embodiments another plurality of fins extends form the surface of the base plate, the another plurality of fins being arranged within the first portion.

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 another plurality of fins includes a first plurality of fins arranged at the central portion.

In addition to one or more of the features described herein, or as an alternative, further embodiments the first plurality of fins are substantially identical.

In addition to one or more of the features described herein, or as an alternative, further embodiments a 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 another plurality of fins includes a second plurality of fins arranged at the at least one end.

In addition to one or more of the features described herein, or as an alternative, further embodiments the second plurality of fins are substantially identical.

In addition to one or more of the features described herein, or as an alternative, further embodiments a height of the second 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 a height of the second plurality of fins is different relative to a height of the first plurality of fins.

In addition to one or more of the features described herein, or as an alternative, further embodiments no fins are arranged at the first portion 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 further comprises a base plate having a first portion vertically aligned with a portion of the fan assembly and a second portion arranged vertically below the fan assembly. A plurality of fins extends from the second 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 height of the plurality of fins varies to form at least one angled surface.

In addition to one or more of the features described herein, or as an alternative, further embodiments no fins are arranged at the first portion of the base plate.

In addition to one or more of the features described herein, or as an alternative, further embodiments comprising another plurality of fins arranged at the first portion of the base plate, wherein a configuration of the another plurality of fins is different than a configuration of the plurality of fins.

In addition to one or more of the features described herein, or as an alternative, further embodiments a gap is defined between the another plurality of fins arranged within the first portion and the fan assembly.

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.

DETAILED DESCRIPTION

With reference now toFIG.1, an example of an outdoor unit or coil unit20of a heating, ventilation, and air conditioning (HVAC) system is illustrated. The coil unit20includes a heat exchanger22and a compressor24fluidly coupled to the heat exchanger22and configured to pump refrigerant through the HVAC system. In the illustrated, non-limiting embodiment, the compressor24is positioned within the interior of the heat exchanger22; however, embodiments having a compressor24arranged at another location are also contemplated herein. Further, the planform of the heat exchanger22may be any suitable shape, including but not limited to square, rectangular, circular, or another shape. The coil unit20may include a floor pan or base pan26configured to receive the heat exchanger22and maintain the heat exchanger22at a desired position. Arranged generally adjacent to a surface of the heat exchanger22is a fan assembly28configured to draw ambient air radially inward, through the heat exchanger22after which the heated air A is discharged upwardly through an opening (not shown).

In the illustrated, non-limiting embodiment, the compressor24is a variable speed compression device having a variable speed motor driven by a variable frequency drive (VFD). The one or more power electronic devices30that form the variable frequency drive may be mounted within the coil unit20, such as between two adjacent ends of the heat exchanger22.

Because the at least one power electronic device30generates waste heat during operation, the coil unit20includes a heat sink32configured to remove heat from the power electronic devices30. In an embodiment, the airflow A being driven through the coil unit20by the fan assembly28is used as a cooling fluid to remove heat from the power electronic devices30via the heat sink32. However, it should be understood that the heat sink32as described herein may be used in combination with other means for cooling the power electronic devices30, such as a refrigerant heat exchanger for example.

In the various embodiments of the heat sink32illustrated herein, the heat sink32includes a base plate34and a plurality of fins36extending from one or more portions of the base plate34. The base plate34is formed from a thermally conductive material and is mounted at an interior of the coil unit20, in axial alignment with at least a portion of the power electronics devices30. The base plate34may be made from a single material. However, embodiments where the base plate34includes a plurality of different materials are also contemplated herein. For example, as best shown inFIG.8B, the base plate34includes a plurality of layers35a,35bof different materials. In an embodiment, the material of the layer35aof the base plate34configured to mount and receive heat from the power electronic devices30has a higher thermal conductivity than the remainder of the layers of the base plate. In an embodiment, the layer35aof the base plate34configured to mount and receive heat from the power electronic devices30is a copper material.

In an embodiment, all or at least a portion of the base plate34is also in vertical alignment, for example within the same horizontal plane, with a portion of the rotatable blades38of the fan assembly28. Further, the base plate34may be elongated in length such that when installed relative to the coil unit20, a first portion40of the base plate34is arranged horizontally adjacent to the fan blades38and a second portion42of the base plate34is disposed vertically below the fan blades38(seeFIG.2).

In the illustrated, non-limiting embodiment, best shown inFIGS.3A-3C,4, and5, the base plate34has a non-planar configuration. As shown, the base plate34is substantially symmetrical and includes a central portion44and at least one end portion46, such as two end portions46arranged at opposite sides of the central portion44. The end portions46may be offset from the plane of the central portion44. In such embodiments, the end portions46may be defined via a first and second bend formed in the base plate34. However, it should be understood that embodiments where at least a portion of the base plate34has another configuration, such as a substantially planar configuration (seeFIGS.6A-6D), are also within the scope of the disclosure.

The plurality of fins36extends from one or more surfaces of the base plate34, such as from the first portion40and/or the second portion42at a first surface, toward an interior of the coil unit20. Although the plurality of fins36is shown extending substantially perpendicularly from the base plate34, embodiments where one or more of the fins36extends at another angle are also contemplated herein. The fins36may extend across the entire width or only a portion of the width of the base plate34. In an embodiment, the plurality of fins36is located at only the central portion44of the base plate34(seeFIGS.4,5A,5B, and5D). However, in other embodiments, a first plurality of fins36ais located at the central portion44of the base plate34and a second plurality of fins36bis located at one or both of the end portions46of the base plate34.

The configuration of the plurality of fins36may be substantially identical. Accordingly, in instances where the heat sink32includes a plurality of first fins36aand a plurality of second fins36b, the configuration of each of the first plurality of fins36ais identical to each of the second plurality of fins36b. However, in other embodiments, the configuration of the second plurality of fins36bdiffers from the configuration of the first plurality of fins36a. Further, the configuration of each fin within the first plurality of fins36aand/or the second plurality of fins36bmay be substantially identical, or may vary. For example, in an embodiment best shown inFIGS.3A-3C, the first plurality of fins36aarranged at the central portion44of the base plate34vary in height, measured perpendicular to the surface of the base plate34. For example, the height of the fins36amay gradually increase (uniformly or non-uniformly) from the center of the central portion44of the base plate34toward the end portions46thereof.

Because the plurality of fins36aand/or36bare positioned radially outward of the fan blades38(seeFIG.3A), the height of the fins36aand/or36bmay vary across the width of the base plate34to achieve a general curvature (viewed via a plan view), such as a curvature similar to the periphery of the adjacent fan blades38. For example, in one of the non-limiting embodiments illustrated inFIG.5, the heat sink32only includes a first plurality of fins36amounted at the central portion44of the base plate34and the height of the fins36avaries to form a curvature. In another embodiment illustrated inFIGS.3A-3C and5C, the base plate34includes a first plurality of fins36aat the central portion44and a second plurality of fins36bat the end portions46, and the first and second plurality of fins36a,36bcooperate to define a curvature. However, embodiments where the curvature is only defined by varying either the first plurality of fins36aor the second plurality of fins36b, but not both, is also contemplated herein.

In an embodiment, the height of the fins36aand/or36bis selected to maintain a constant radius defined by the fins, or alternatively, to maintain a constant gap between the fan blades38and the fins36aand/or36b. However, in an embodiment, the gap measured parallel to the height of the fins36aand/or36bmay vary over the width of the base plate34. For example, the gap between the first plurality of fins36aarranged at the middle of the central portion44of the base plate34and the fan blades38may be less than the gap between the first plurality of fins36aclosest to the end portions46or the second plurality of fins36bat the end portions46of the base plate34and the fan blades38. Regardless of whether the gap is constant or variable, a minimum gap between the fan blades38and the fins36aand/or36bis at least about 5 mm and in some embodiments, the gap between the fins36aand/or36band the fan blades38may 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 plate34, the height of the fins36aand/or36bmay gradually increase from the end portion46of the base plate34towards the central portion44of the base plate34. For example, in the non-limiting embodiment, ofFIGS.6A-6D, the base plate34includes a first plurality of fins36aand a second plurality of fins36b, and the height of the fins36blocated at each end portion46of the base plate34is shorter than the height of the fins36aarranged at the center44of the base plate34. As shown, the height of the outermost fins36bmay taper from the maximum to the minimum such that in a plan view, the fins36aand36bappear to have or form at least one angled surface. In the illustrated, non-limiting embodiment, the height of the fins36bvaries such that the fins form a symmetrical trapezoid (seeFIG.6D).

The first and/or the second plurality of fins36a,36bmay be configured to extend over the substantial entirety, or alternatively, over only a portion of a length of the base plate34. In the illustrated, non-limiting embodiment, best shown inFIGS.2-5, the first and/or second plurality of fins36aand/or36bextends over the substantially entire length of the base plate34, measured parallel to the fan axis X. In such embodiments, the base plate34, may but need not include the second portion42disposed vertically below the fan blades38. In another embodiment, the first and/or second plurality of fins36a,36bextends over only a portion of the length of the base plate34, such as over only the first portion40of the base plate34aligned with the plurality of fan blades38, or alternatively, over only the second portion42of the base plate34arranged vertically below the fan blades38(seeFIGS.6A-6D).

Further, with reference now toFIG.7, in an embodiment, the first portion40of the base plate34aligned with the fan blades38may have a first plurality of fins36aarranged at the central portion44and a second plurality of fins36barranged at the ends46of the first portion40of the base plate34as previous described herein. In an embodiment, the second portion42of the base plate34located underneath the fan blades38includes a third plurality of fins36c. The third plurality of fins36cmay extend over the entire width, or alternatively, over only a portion of the width of the base plate34. In other embodiments, best shown inFIGS.8A and8B, the first portion40of the base plate34may have only the first plurality of fins36aarranged at the central portion44, or alternatively, only the second plurality of fins36barranged at at least one end portion46, while the second portion42of the base plate34located underneath the fan blades38includes the third plurality of fins36c.

In embodiments where the heat sink32includes fins36within both the first portion40and the second portion42of the base plate34, a fin within the second portion42may be vertically aligned with an adjacent fins of the first portion40to define an uninterrupted fluid flow path extending over an entire length of the base plate34. However, embodiments where vertically stacked fins36are offset from one another are also within the scope of the disclosure.

The configuration of the base plate34, the first plurality of fins36a, the second plurality of fins36b, and/or the third plurality of fins36cmay vary based on the loading of the HVAC system as well as the adjacent components within the coil unit20. For example, in the illustrated, non-limiting embodiment ofFIG.7, the fin height of the first plurality of fins36aand the second plurality of fins36bvaries to forms a curvature when viewed in plan form. However, in the embodiments ofFIGS.8A and8B, the first plurality of fins36ahas a substantially uniform height. Because the third plurality of fins36c, is positioned underneath the fan assembly28, in an embodiment, the maximum fin height of the third plurality of fins36cis substantially greater than a maximum fin height of the first plurality of fins36a, and in some embodiments, than the second plurality of fins36b. In the illustrated, non-limiting embodiment, the fin height of the third plurality of fins36cincreases from the edge portions46of the base plate34toward the central portion44to form a contour having angled sides when viewed in plan form. However, it should be understood that a heat sink32having any suitable fin configuration that does not interfere with the adjacent components of the coil unit20are within the scope of the disclosure.

As the fan blades38rotate about the fan axis, the airflow A moved by the fan assembly28moves over and through the plurality of fins36of the base plate, thereby removing heat from the fins36and the base plate46of the heat sink32and cooling the at least one power electronics device30. A coil unit20having a heat sink32as illustrated and described herein will enhance the heat transfer from the power electronic devices30, thereby increasing the efficiency of the coil unit20.