Cooling device

Abstract

This cooling device comprises: an axial fan (2) that generates a flow of a coolant; and a heat sink (1) that is thermally connected to an object (100) to be cooled and that allows the coolant to flow between a plurality of fins (11, 12). The plurality of fins (11, 12) include a pair of first fins (11a, 11b) and a second fin (12) provided between the pair of first fins (11a, 11b). The second fin (12) forms a first flow path (C1), through which the coolant flows, between the second fin (12) and one first fin (11a). The second fin (12) forms a second flow path (C2), through which the coolant flows, between the second fin (12) and the other first fin (11b). In the second fin (12), a plurality of communication holes (13) communicating between the first flow path (C1) and the second flow path (C2) are intermittently provided along the extension direction of the second fin (12).

Description

cooling device

[0001] The present invention relates to a cooling device.

[0002] Patent Document 1 discloses a heat sink. Fin groups, each consisting of a plurality of raised heat dissipation fins arranged at a predetermined pitch in the left-right direction of the base plate, are arranged in multiple rows in the front-rear direction of the base plate on the surface of the heat sink. The front-rear direction of the base plate is set to the direction of flow of cooling air. When viewed in the direction of flow of cooling air, the amount of left-right misalignment between the fins of one fin group and the fins of the other fin group of two rows of fin groups adjacent to each other in the front-rear direction of the base plate varies over the entire height range from the base position to the tip position of the fins.

[0003] Japanese Patent Application Laid-Open No. 2009-290004

[0004] However, in the method disclosed in Patent Document 1, the coolant flows while hitting a group of fins arranged in the direction of the coolant flow, which results in a large pressure loss of the coolant flow downstream of the heat sink, resulting in a problem of reduced heat dissipation performance downstream.

[0005] An object of the present invention is to provide a cooling device that can improve the heat dissipation performance on the downstream side of the heat sink.

[0006] A cooling device according to one aspect of the present invention includes a heat sink in which a coolant flowing from a first coolant flow generating device flows between a plurality of fins. The plurality of fins include a pair of first fins and a second fin that forms a first flow path for the coolant between one of the first fins and a second flow path for the coolant between the other of the first fins. The second fins have a plurality of communication holes extending in an extension direction of the second fins, which communicate between the first flow path and the second flow path.

[0007] According to one aspect of the present invention, it is possible to improve the heat dissipation performance on the downstream side of the heat sink.

[0008] FIG. 1 is a perspective view schematically showing the configuration of a cooling device according to a first embodiment. FIG. 2 is a view showing a main part of a heat sink included in the cooling device according to the first embodiment. FIG. 3 is a view showing the relationship between the width of a communication hole and cooling performance. FIG. 4 is a view showing the relationship between the width of a communication hole and cooling performance. FIG. 5 is a view showing the relationship between the width of a communication hole and cooling performance. FIG. 6 is a view showing a main part of a heat sink included in a cooling device according to a second embodiment. FIG. 7 is a view showing the relationship between the width of a communication hole and cooling performance. FIG. 8 is a view showing the relationship between the width of a communication hole and cooling performance. FIG. 9 is a view showing the relationship between the width of a communication hole and cooling performance. FIG. 10 is a view showing a modified example of a second refrigerant flow generating device. FIG. 11 is a view showing a modified example of a communication hole.

[0009] (First embodiment) Hereinafter, a cooling device according to a first embodiment will be described with reference to the drawings. In this embodiment, the structure of the cooling device will be described using the left-right direction, the front-rear direction, and the up-down direction. The left-right direction and the front-rear direction correspond to two directions that are orthogonal to the horizontal direction, and the up-down direction corresponds to the vertical direction, but the use of the cooling device is not limited to these directions. In the drawings, the left-right direction, the front-rear direction, and the up-down direction are indicated by X, Y, and Z, respectively.

[0010] 1 and 2, the cooling device is a device that cools a heat-generating body that is a cooling target 100. For example, the cooling target 100 may be a heat-generating device mounted on an automobile such as an electric vehicle or a hybrid vehicle, and in particular, a converter that converts large amounts of power, which is a type of power conversion device.

[0011] The cooling device includes a heat sink 1 and an axial fan 2. Note that the axial fan 2 is not shown in FIG.

[0012] As shown in Fig. 1, the heat sink 1 dissipates heat generated in a cooling target 100. The heat sink 1 has a base plate 10 thermally connected to the cooling target 100, and a plurality of fins 11 and 12. The base plate 10 and the plurality of fins 11 and 12 are integrally formed from a metal material such as aluminum. The heat sink 1 can be produced using, for example, a 3D printer, and can be formed into a complex shape through fine dimensional control.

[0013] The base plate 10 is a flat plate and has a pair of main surfaces 10a and 10b spaced apart in the vertical direction Z. One main surface 10a of the base plate 10 is in contact with the cooling target 100. The other main surface 10b of the base plate 10 has a plurality of fins 11 and 12.

[0014] The multiple fins 11, 12 are provided on the base plate 10. The multiple fins 11, 12 extend parallel to each other in the front-rear direction Y. The individual fins 11, 12 are at the same height, stand upright in the up-down direction Z, and are arranged at equal intervals in the left-right direction X.

[0015] The multiple fins 11, 12 include multiple first fins 11 and multiple second fins 12. The first fins 11 and the second fins 12 are alternately arranged in the left-right direction X. That is, one second fin 12 is present between a pair of first fins 11. The spaces between the first fins 11 and the second fins 12 function as flow paths for the flow of a coolant (e.g., air), and multiple flow paths are formed corresponding to the multiple fins 11, 12. Each flow path extends linearly along the front-rear direction Y.

[0016] The axial fan 2 is a first refrigerant flow generating device that generates a refrigerant flow. The axial fan 2 is disposed directly opposite the heat sink 1 so that the refrigerant flow is along the front-rear direction Y. That is, the refrigerant generated by the axial fan 2 flows through individual flow paths along the extension direction of the multiple fins 11, 12. Note that the first refrigerant flow generating device is not limited to the axial fan 2, and may be a sirocco fan or the like.

[0017] The detailed structure of the heat sink 1 will be described below with reference to Fig. 2. Fig. 2 representatively shows a pair of first fins 11a, 11b and a second fin 12 located between the first fins 11a, 11b, out of the multiple fins 11, 12 shown in Fig. 1. In Fig. 2, of the pair of first fins 11a, 11b, one first fin 11a is depicted above the second fin 12, and the other first fin 11b is depicted below the second fin 12.

[0018] A first flow path C1 and a second flow path C2 are formed between a pair of first fins 11a, 11b and the second fin 12. The first flow path C1 is located between one of the first fins 11a and the second fin 12. The first flow path C1 extends from the upstream end 11aa of one of the first fins 11a and the upstream end 12a of the second fin 12 to the downstream end 11ab of one of the first fins 11a and the downstream end 12b of the second fin 12. The refrigerant flow in the first flow path C1 is referred to as a first refrigerant flow F1. The second flow path C2 is located between the other of the first fins 11b and the second fin 12. The second flow path C2 extends from the upstream end 11ba of the other of the first fins 11b and the upstream end 12a of the other of the second fins 12 to the downstream end 11bb of the other of the first fins 11b and the downstream end 12b of the other of the second fins 12. The refrigerant flow in the second flow path C2 is referred to as a second refrigerant flow F2.

[0019] The second fin 12 has a plurality of communication holes 13 that communicate between the first flow path C1 and the second flow path C2. The plurality of communication holes 13 are provided at a predetermined pitch P1. In this embodiment, the plurality of communication holes 13 are provided intermittently in the downstream region of the second fin 12, i.e., from a position offset a certain distance downstream from the upstream end 12a of the second fin 12 to the downstream end 12b of the second fin 12.

[0020] Each communication hole 13 is continuously formed with the same length as the second fin 12 along the up-down direction Z, i.e., a length extending from the base plate 10 to the upper end of the second fin 12. Each communication hole 13 has a predetermined width t1. The width t1 of the communication hole 13 is the length in the refrigerant flow direction, i.e., the front-rear direction Y. Specifically, the width t1 of the communication hole 13 is set to be equal to or greater than the thickness t2 of the second fin 12. The thickness t2 of the second fin 12 can also be rephrased as the distance between the first flow path C1 and the second flow path C2. Meanwhile, when the length from the first fins 11a, 11b to the second fin 12 in the left-right direction X is defined as the width t3 of the first and second flow paths C1, C2, the width t1 of the communication hole 13 is set to be equal to or less than the width t3 of the first and second flow paths C1, C2.

[0021] 3 to 5 are diagrams showing the relationship between the width t1 of the communication holes 13 and cooling performance. FIG. 3 shows the cooling performance when the width t1 of each communication hole 13 is changed from 0.0 mm to 6.0 mm, assuming that the thickness t2 of the second fin 12 is 1.6 mm and the width t3 of the first and second flow paths C1 and C2 is 5.0 mm. The refrigerant inlet wind speed of each flow path C1 and C2 is 1.2 m / s. Each communication hole 13 is located 1.6 mm away from the next communication hole 13 located upstream. That is, the pitch P1 of each communication hole 13 is the sum of the width t1 and 1.6 mm.

[0022] When the width t1 of the communication hole 13 is 0.0 mm, i.e., when the second fin 12 does not have the communication hole 13, the first and second refrigerant flows F1 and F2 through the first and second flow paths C1 and C2, respectively. In each of the flow paths C1 and C2, a boundary layer appears downstream of the refrigerant flow. That is, in each of the flow paths C1 and C2, the refrigerant flows slower near the fin walls than in the center of the flow path. As a result, the efficiency of heat transfer to the first fins 11a and 11b and the second fin 12 is poor downstream of the refrigerant (heat sink 1), resulting in reduced cooling performance.

[0023] When the width t1 of the communication holes 13 is greater than 0.0 mm, i.e., when the communication holes 13 are provided in the second fins 12, the following occurs: First, when the width t1 of the communication holes 13 is smaller than 1.6 mm, i.e., smaller than the thickness t2 of the second fins 12, the first and second refrigerant flows F1 and F2 flow through the first and second flow paths C1 and C2, respectively, without being significantly affected by the multiple communication holes 13.

[0024] On the other hand, when the width t1 of the communicating holes 13 is 1.6 mm or greater, i.e., when the width t1 of the communicating holes 13 is greater than or equal to the thickness t2 of the second fin 12, cooling performance tends to improve. This is because the wider width t1 of the communicating holes 13 reduces pressure loss and makes it easier for the refrigerant to pass through the communicating holes 13. As a result, when a portion of the first refrigerant flow F1 passes through the communicating holes 13 and enters the second flow path C2, it collides with the second refrigerant flow F2. The second refrigerant flow F2 is disturbed by the first refrigerant flow F1 that passed through the communicating holes 13, and a portion of the second refrigerant flow F2 flows toward the first fin 11b that defines the second flow path C2. When a portion of the second refrigerant flow F2 collides with the first fin 11b and changes direction toward the second fin 12, a portion of the second refrigerant flow F2 passes through the communicating holes 13 and enters the first flow path C1. The first refrigerant flow F1 is disturbed by the second refrigerant flow F2 that has passed through the communication holes 13, and part of the first refrigerant flow F1 flows toward the first fins 11a that define the first flow paths C1. When part of the first refrigerant flow F1 collides with the first fins 11a and changes direction toward the second fins 12, part of the first refrigerant flow F1 passes through the communication holes 13 and enters the second flow paths C2.

[0025] The second fin 12 is provided with a plurality of communication holes 13 at intervals, causing turbulence in the refrigerant at each communication hole 13. As a result, pulsation of the refrigerant flow caused by the communication holes 13 continues all the way to the downstream end of each flow path C1, C2. Therefore, even on the downstream side of the refrigerant flow, the refrigerant flows at a high speed along the wall surfaces of the first fins 11 a, 11 b and the second fin 12, improving the efficiency of heat transfer to the first fins 11 a, 11 b and the second fin 12 and improving the cooling performance on the downstream side of the heat sink 1.

[0026] In this way, the provision of the communication holes 13 disrupts the flow of the refrigerant, thereby improving the efficiency of heat transfer to the first fins 11a, 11b and the second fin 12. On the other hand, if the width t1 of the communication holes 13 is large, the heat transfer area of ​​the second fin 12 decreases, which tends to reduce cooling performance. Therefore, it is preferable that the width t1 of the communication holes 13 be within a range that provides the required cooling performance, for example, equal to or less than the width t3 of the first and second flow paths C1, C2.

[0027] Fig. 4 shows the cooling performance when the width t1 of each communication hole 13 is changed from 0.0 mm to 6.0 mm when the thickness t2 of the second fin 12 is 3.2 mm and the width t3 of the first and second flow paths C1, C2 is 5.0 mm. Fig. 5 shows the cooling performance when the width t1 of each communication hole 13 is changed from 0.0 mm to 6.0 mm when the thickness t2 of the second fin 12 is 1.6 mm and the width t3 of the first and second flow paths C1, C2 is 7.5 mm. Other conditions are the same as those shown in Fig. 3.

[0028] Thus, even when the thickness t2 of the second fin 12 was different (FIG. 4), or when the width t3 of the first and second flow paths C1, C2 was different (FIG. 5), results similar to those shown in FIG. 3 were obtained.

[0029] As described above, the cooling device of this embodiment includes an axial fan 2 that generates a refrigerant flow, and a heat sink 1 that is thermally connected to a cooling target 100 and through which the refrigerant flows between a plurality of fins 11, 12. The plurality of fins 11, 12 includes a pair of first fins 11 a, 11 b and a second fin 12 that is provided between the pair of first fins 11 a, 11 b. The second fin 12 forms a first flow path C1 through which the refrigerant flows between one of the first fins 11 a and the second fin 11 b, and forms a second flow path C2 through which the refrigerant flows between the other of the first fins 11 b. The second fin 12 is provided with a plurality of communication holes 13 that communicate between the first flow path C1 and the second flow path C2, and are provided intermittently along the extension direction of the second fin 12.

[0030] In a cooling device with this structure, a refrigerant flow is generated by the axial fan 2. The refrigerant flow generated by the axial fan 2 passes through each of the flow paths between the multiple fins 11 and 12. At this time, the flow of the refrigerant is disturbed by the communication holes 13 in the first and second flow paths C1 and C2 adjacent to each other across the second fin 12. Furthermore, because the multiple communication holes 13 are intermittently provided downstream, turbulence of the refrigerant occurs in each communication hole 13, causing pulsation of the refrigerant flow to continue all the way to the downstream end of each flow path C1 and C2. This allows the refrigerant to flow at a high speed along the wall surfaces of the first fins 11a and 11b and the second fin 12 downstream, improving the efficiency of heat transfer to the first fins 11a and 11b and the second fin 12. This improves the cooling performance downstream of the heat sink 1.

[0031] In this embodiment, the width t1 of each of the plurality of communication holes 13 is equal to or greater than the thickness t2 of the second fin 12. With this configuration, the wider width t1 of the communication holes 13 reduces pressure loss and makes it easier for the refrigerant to pass through the communication holes 13. This makes it possible to effectively obtain pulsation of the refrigerant flow caused by the communication holes 13.

[0032] In this embodiment, the width t1 of each of the plurality of communication holes 13 is equal to or less than the width t3 of the first and second flow paths C1 and C2. The heat transfer effect due to the turbulence in the refrigerant flow is greater than the heat transfer reduction effect of the second fins 12, thereby improving cooling performance.

[0033] Second Embodiment A cooling device according to a second embodiment will be described with reference to Fig. 6. The cooling device according to the second embodiment differs from the first embodiment in that it includes a second refrigerant generation device plate. Hereinafter, a description of the configuration common to the first embodiment will be omitted, and the description will focus on the differences.

[0034] 6, the first flow path C1 is provided with a plasma actuator 17 as a second refrigerant flow generating device that generates a refrigerant flow. The plasma actuator 17 is disposed upstream of the communication hole 13 of the second fin 12. The refrigerant flow generated by the plasma actuator 17 is added to the first refrigerant flow F1.

[0035] The plasma actuator 17 is a device composed of electrodes and a dielectric, and when a high voltage is applied to the electrodes, it forcibly generates a vortex flow in the same direction as the first refrigerant flow F1. The plasma actuator 17 is burst-driven by controlling the applied voltage by a control unit (not shown). Burst driving of the plasma actuator 17 causes the flow of the refrigerant to fluctuate periodically (pulsation).

[0036] The plasma actuator 17 disturbs the first coolant flow F1 in the first flow path C1, creating a difference between the first coolant flow F1 and the second coolant flow F2. In this manner, a portion of the turbulent first coolant flow F1 passes through the communication hole 13 and enters the second flow path C2, significantly disturbing the flow in the second flow path. This results in greater coolant turbulence in the first and second flow paths C1 and C2. This allows the coolant to flow at a higher speed along the wall surfaces of the first fins 11a, 11b and the second fins 12 downstream of the coolant flow, improving the efficiency of heat transfer to the first fins 11a, 11b and the second fins 12 and improving cooling performance.

[0037] Figures 7 to 9 are diagrams showing the relationship between the width t1 of communication hole 13 and cooling performance when plasma actuator 17 is driven. The experimental conditions in Figures 7 to 9 are the same as those in Figures 3 to 5, respectively. Note that in Figures 7 to 9, the experimental results when plasma actuator 17 was driven are depicted by dashed lines, and the experimental results when plasma actuator 17 was not installed (the experimental results shown in Figures 3 to 5) are depicted by solid lines.

[0038] 7 to 9 , by providing multiple communication holes 13 in the second fin 12, the coolant flows at a high speed along the wall surfaces of the first fins 11 a, 11 b and the second fin 12 even downstream of the coolant flow, improving the efficiency of heat transfer to the first fins 11 a, 11 b and the second fin 12 and improving cooling performance. Furthermore, by driving the plasma actuator 17, greater coolant turbulence can be generated in the first and second flow paths C1, C2. This significantly improves cooling performance downstream of the coolant flow compared to a configuration without the plasma actuator 17.

[0039] Furthermore, the width t1 of each of the plurality of communication holes 13 is equal to or greater than the thickness t2 of the second fin 12. With this configuration, the wider width t1 of the communication holes 13 reduces pressure loss and makes it easier for the refrigerant to pass through the communication holes 13. This makes it possible to effectively obtain pulsation of the refrigerant flow caused by the communication holes 13.

[0040] In this embodiment, the width t1 of each of the plurality of communication holes 13 is equal to or less than the width t3 of the first and second flow paths C1 and C2. The heat transfer effect due to the turbulence in the refrigerant flow is greater than the heat transfer reduction effect of the second fins 12, thereby improving cooling performance.

[0041] When the plasma actuator 17 is provided in the first flow path C1, the pitch P1 of the multiple communication holes 13 may be set to correspond to the wavelength of the pulsating refrigerant. This allows the pulsation generated by the plasma actuator 17 to correspond to the pulsation generated by the multiple communication holes 13, so that the flow of refrigerant generated by the plasma actuator 17 can be smoothly guided to the multiple communication holes 13.

[0042] In this embodiment, the plasma actuator 17 is used as an example of the second coolant flow generating device. However, the second coolant flow generating device is not limited to this as long as it generates a coolant flow. For example, the second coolant flow generating device may be a micro-blower that draws in and discharges coolant.

[0043] As shown in FIG. 10 , the second refrigerant flow generating device may include a partition plate 18 that forms a narrow flow path Cs between itself and the first fin 11a, and a protrusion 19 attached to the first fin 11a downstream of the partition plate 18. With this configuration, a portion of the first refrigerant flow F1 flows through the narrow flow path Cs. Because the narrow flow path Cs is narrower than the first flow path C1, the refrigerant flowing through the narrow flow path Cs is accelerated. After passing through the narrow flow path Cs, the fast-flowing refrigerant flow reaches the protrusion 19 downstream of the partition plate 18. The refrigerant flow that has passed through the narrow flow path Cs collides with the protrusion 19, forcibly generating a vortex flow in the same direction as the first refrigerant flow F1. This provides an effect similar to that of the plasma actuator 17 described above.

[0044] In the first or second embodiment described above, the plurality of communication holes 13 are provided between a position offset downstream from the upstream end 12a of the second fin 12 by a certain distance and the downstream end 12b of the second fin 12. However, the range in which the plurality of communication holes 13 are provided is not limited thereto. For example, the plurality of communication holes 13 may be provided between the upstream end 12a of the second fin 12 and the downstream end 12b of the second fin 12. This allows the refrigerant flow to be disturbed throughout the entire flow path. However, if the speed of the refrigerant entering the first and second flow paths C1 and C2 is slow, the turbulence of the refrigerant downstream will be relatively weak. In addition, the heat dissipation area of ​​the second fin 12 will decrease as the number of communication holes 13 increases. Therefore, it is preferable to determine the location and range of the plurality of communication holes 13 depending on the heat dissipation performance required of the heat sink 1.

[0045] In the first or second embodiment described above, each communication hole 13 provided in the second fin 12 is configured by a single communication element that is continuous in the vertical direction Z. However, as shown in Fig. 11, each communication hole 13 may be configured by a plurality of communication elements that are provided intermittently along the vertical direction Z and that communicate between the first flow path C1 and the second flow path C2. In this case, each communication element is not limited to a rectangular shape and may have any shape, such as a triangular shape, a polygonal shape, or a circular shape.

[0046] Although the embodiments of the present invention have been described above, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure.

[0047] 1: heat sink, 2: axial fan (first refrigerant flow generating device), 10: base plate, 11 (11a, 11b): fins (first fins), 12: fins (second fins), 13: communication holes, 17: plasma actuator, 18: partition plate, 19: protrusion, C1, C2: first flow path, second flow path

Claims

1. A cooling device comprising: a first refrigerant flow generating device that generates a flow of refrigerant; and a heat sink having a plurality of fins extending parallel to each other on a base plate that is thermally connected to an object to be cooled, with the refrigerant flowing between the plurality of fins, wherein the plurality of fins include a pair of first fins and a second fin that is provided between the pair of first fins and forms a first flow path through which the refrigerant flows between one of the first fins and a second flow path through which the refrigerant flows between the other first fin, and wherein the second fins have a plurality of communication holes that are provided intermittently along the extension direction of the second fins, connecting the first flow path and the second flow path.

2. A cooling device according to claim 1, wherein a second refrigerant flow generating device for generating a flow of the refrigerant is provided in the first flow path upstream of the plurality of communication holes.

3. The cooling device according to claim 2, wherein the second coolant flow generating device is a plasma actuator, and the plasma actuator is burst-driven.

4. The cooling device according to claim 1, wherein the width of each of said plurality of communication holes is equal to or greater than the thickness of said second fin.

5. A cooling device according to claim 1 or 2, wherein the width of each of said plurality of communication holes is equal to or less than the distance from said other first fin to said other second fin.

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