Cooling device

Abstract

This cooling device comprises: an axial flow fan (2) that generates a flow of a refrigerant; and a heatsink (1) in which the refrigerant flows through channels between first and second fins (11a, 11b) that extend in parallel with each other. The heatsink (1) has a partition plate (12) provided between the first and second fins (11a, 11b), and a protrusion (13) provided on the wall surface of the second fin (11b). The flow velocity of a second refrigerant flow (F2) flowing through a second channel (C2) between the second fin (11b) and the partition plate (12) is higher than the flow velocity of a first refrigerant flow (F1) flowing through a first channel (C1) between the first fin (11a) and the partition plate (12). The protrusion (13) redirects the second refrigerant flow (F2) flowing from the second channel (C2) toward the first fin (11a).

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 coolant flow generating device that generates a coolant flow, and a heat sink in which the coolant flows through a flow path between first and second fins that extend parallel to each other. The heat sink has a partition plate provided between the first and second fins, and a protrusion provided on a wall surface of the second fin. The flow velocity of the second coolant flowing through the second flow path between the second fin and the partition plate is faster than the flow velocity of the first coolant flowing through the first flow path between the first fin and the partition plate. The protrusion changes the direction of the second coolant flowing from the second flow path toward the first fin.

[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 the main parts of a heat sink included in the cooling device according to the first embodiment. Fig. 3 is a view showing the relationship between the distance d of the protrusions and cooling performance. Fig. 4 is a view showing the main parts of a heat sink included in a cooling device according to a second embodiment. Fig. 5 is a view showing a modified example of the heat sink included in the cooling device according to the second embodiment. Fig. 6 is a view showing the main parts of a heat sink included in a cooling device according to a third embodiment.

[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 is defined using the left-right direction, the front-rear direction, and the up-down direction. In this embodiment, 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 this is not limited thereto. 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, as well as a partition plate 12 and a protrusion 13, which will be described later, are omitted from Fig. 1 .

[0012] 1, the heat sink 1 dissipates heat generated in the 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 formed on the base plate 10. The base plate 10 and the plurality of fins 11 are integrally formed from a metal material such as aluminum.

[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.

[0014] The multiple fins 11 are provided on the base plate 10 (main surface 10b) and extend parallel to each other in the front-rear direction Y. The individual fins 11 stand upright at the same height in the up-down direction Z and are arranged at equal intervals in the left-right direction X. The space between adjacent pairs of fins 11 functions as a flow path for the flow of refrigerant (e.g., air), and multiple flow paths are formed corresponding to the multiple fins 11. Each flow path extends linearly in the front-rear direction Y.

[0015] The axial fan 2 is a 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. Note that the refrigerant flow generating device is not limited to the axial fan 2, and may be a sirocco fan or the like.

[0016] The detailed structure of the heat sink 1 will be described below with reference to Fig. 2. Fig. 2 shows a pair of adjacent fins 11a and 11b among the multiple fins 11 shown in Fig. 1. Hereinafter, one fin 11a of the pair of fins 11a and 11b will be referred to as the first fin 11a, and the other fin 11b will be referred to as the second fin 11b.

[0017] The heat sink 1 further includes a partition plate 12 and a protrusion 13 .

[0018] The partition plate 12 is provided between the first and second fins 11a, 11b and stands upright in the vertical direction Z. The height of the partition plate 12 in the vertical direction Z is the same as the height of the first and second fins 11a, 11b in the vertical direction Z. The partition plate 12 may be formed integrally with the base plate 10 together with the fins 11, or the partition plate 12 alone may be attached separately.

[0019] In this embodiment, the partition plate 12 extends parallel to the first and second fins 11a, 11b. The upstream end 12a of the partition plate 12 in the refrigerant flow direction (front-rear direction Y) is located upstream of the upstream ends 11aa, 11ba of the first and second fins 11a, 11b in the refrigerant flow direction. Meanwhile, the downstream end 12b of the partition plate 12 in the refrigerant flow direction is located upstream of the downstream ends 11ab, 11bb of the first and second fins 11a, 11b in the refrigerant flow direction. In other words, the partition plate 12 extends a shorter length than the first and second fins 11a, 11b.

[0020] The partition plate 12 is disposed closer to the second fin 11b than the intermediate portion between the first and second fins 11a and 11b in the direction perpendicular to the refrigerant flow (the left-right direction X). The width from the second fin 11b to the partition plate 12 in the left-right direction X is expressed as "width t."

[0021] The partition plate 12 defines first to third flow paths C1 to C3 between the first and second fins 11a, 11b. The first flow path C1 is located between the first fin 11a and the partition plate 12. Of the refrigerant flows between the first and second fins 11a, 11b, the refrigerant flow in the first flow path C1 is referred to as the first refrigerant flow F1. The second flow path C2 is located between the second fin 11b and the partition plate 12. Of the refrigerant flows between the first and second fins 11a, 11b, the refrigerant flow in the second flow path C2 is referred to as the second refrigerant flow F2. The third flow path C3 is located downstream of the downstream end 12b of the partition plate 12 in the refrigerant flow direction, and is a flow path where the first refrigerant flow F1 and the second refrigerant flow F2 merge.

[0022] The protrusion 13 is provided on the wall surface of the second fin 11b facing the first fin 11a, and protrudes from the second fin 11b in the left-right direction X. For example, the protrusion 13 is formed integrally with the second fin 11b. The protrusion 13 extends in the up-down direction Z along the wall surface of the second fin 11b at the same height as the second fin 11b. The protrusion 13 is located downstream of the partition plate 12, i.e., within the third flow path C3. The distance from the downstream end 12b of the partition plate 12 to the protrusion 13 is defined as "distance d." This distance d is set to be equal to or less than the width t described above (t≧d).

[0023] The amount of protrusion of the protrusion 13 from the second fin 11b (the distance toward the first fin 11a) is defined as the "protrusion amount h." This protrusion amount h is set to be greater than the width t and smaller than the value (T-t) obtained by subtracting the width t from the fin width T (t<h<(T-t)). Here, the fin width T is the distance between the first fin 11a and the second fin 11b in the left-right direction X. In this way, the apex of the protrusion 13 protruding from the second fin 11b toward the first fin 11a reaches the first fin 11a side relative to the partition plate 12. In other words, the protrusion 13 is located directly in front of the second refrigerant flowing out of the second flow path C2. Furthermore, a gap at least equal to the width t is formed between the apex of the protrusion 13 and the first fin 11a.

[0024] The protrusions 13 have a triangular shape when viewed in a plane including the left-right and front-rear directions X and Y. Specifically, the surface of the protrusions 13 facing the second flow paths C2 is formed as an inclined surface that approaches the first fins 11a as it moves downstream. The protrusions 13 are located downstream of the second flow paths C2 and have the function of changing the direction of the second refrigerant flow F2 from the second flow paths C2 toward the first refrigerant flow F1. In this embodiment, the protrusions 13 have a triangular shape to smoothly change the direction of the second refrigerant flow F2. However, the shape is not limited to this as long as it can change the direction of the second refrigerant flow F2 toward the first refrigerant flow F1.

[0025] Such partition plates 12 and protrusions 13 are provided in each flow path (between a pair of adjacent fins 11 (11a, 11b)) of the heat sink 1. However, the partition plates 12 and protrusions 13 do not need to be provided in all flow paths, and may be selectively provided in specific flow paths.

[0026] In a cooling device having such a structure, a flow of refrigerant is generated by the axial fan 2. The flow of refrigerant generated by the axial fan 2 passes through each of the flow paths between the multiple fins 11. At this time, the refrigerant flows in each of the flow paths as follows.

[0027] As shown in FIG. 2 , the flow of refrigerant flowing from the axial fan 2 into the flow passages is divided by the partition plate 12 into a first refrigerant flow F1 flowing through the first flow passage C1 and a second refrigerant flow F2 flowing through the second flow passage C2. The partition plate 12 is positioned close to the second fin 11b. When comparing the cross-sectional areas in the left-right direction X, the cross-sectional area of ​​the second flow passage C2 is smaller than the cross-sectional area of ​​the first flow passage C1. As a result, the refrigerant flowing through the narrower second flow passage C2 is accelerated, and the flow velocity of the second refrigerant flow F2 through the second flow passage C2 becomes faster than the flow velocity of the first refrigerant flow F1 through the first flow passage C1.

[0028] The second refrigerant flow F2, which has a high flow rate, passes through the second flow path C2 and reaches the protrusions 13 located downstream of the partition plate 12. The second refrigerant flow F2 hits the protrusions 13 and changes direction toward the first fins 11a. When the second refrigerant flow F2 reaches the first fins 11a, it hits the first fins 11a and changes direction toward the second fins 11b. The second refrigerant flow F2 moves downstream, repeatedly meandering as it hits the first fins 11a and second fins 11b in succession. At this time, the first refrigerant flow F1 is disturbed by the meandering of the second refrigerant flow F2 and continues to move downstream while being affected by the meandering of the second refrigerant flow F2.

[0029] The meandering of the second refrigerant flow F2, which has a high flow rate, activates the flow of the refrigerant at the boundary (wall surface) between the first and second fins 11 a and 11 b downstream of the first and second fins 11 a and 11 b, i.e., in the third flow path C3, thereby improving the heat dissipation performance downstream of the heat sink 1, i.e., in the third flow path C3.

[0030] 3, the results of a simulation of the relationship between the distance d from the partition plate 12 to the protrusion 13 and the heat dissipation performance will be described. In this simulation, the width T between the first fin 11a and the second fin 11b is 5 mm, the width of the first flow path C1 is 4 mm, and the width t of the second flow path C2 is 1 mm. The distance d was changed in 1 mm increments from 0.0 mm to 6.0 mm.

[0031] At the inlet of the first flow path C1, the flow velocity of the first refrigerant flow F1 is 1.2 m / s. At the inlet of the second flow path C2, the flow velocity of the second refrigerant flow F2 is 2.0 m / s to 4.5 m / s depending on the change in the distance d. Because a volume force that accelerates the flow velocity of the second refrigerant flow F2 is input to the inlet of the second flow path C2, the flow velocity of the second refrigerant flow F2 flowing through the second flow path C2 increases as the distance d increases.

[0032] However, when the distance d is long, the second refrigerant flow F2 flowing out of the second flow path C2 floats before hitting the protrusions 13 installed in the third flow path C3. This causes the angle toward the first fin 11a to become shallower. This narrows the meandering width of the second refrigerant flow F2 in the third flow path C3, or reduces the number of times it meanders. This reduces the number of times the second refrigerant flow F2 hits the first and second fins 11a and 11b. In contrast, when the distance d is equal to or less than the width t of the second flow path C2, the second refrigerant flow F2 flowing out of the second flow path C2 hits the protrusions 13 in a substantially straight line. This causes the second refrigerant flow F2 to flow at a steeper angle toward the first fin 11a after hitting the protrusions 13. This increases the meandering width of the second refrigerant flow F2 and the number of times it meanders. The number of times that the second refrigerant flow F2 collides with the first and second fins 11a and 11b increases, thereby significantly promoting heat transfer.

[0033] As described above, in the cooling device according to this embodiment, the partition plate 12 is disposed between the first and second fins 11a, 11b and extends a shorter length than the first and second fins 11a, 11b. The protrusions 13 are disposed on the wall surface of the second fin 11b facing the first fin 11a. The flow velocity of the second refrigerant flow F2 through the second flow path C2 between the second fin 11b and the partition plate 12 is faster than the flow velocity of the first refrigerant flow F1 through the first flow path C1 between the first fin 11a and the partition plate 12. The protrusions 13 are disposed downstream of the partition plate 12 and redirect the second refrigerant flow F2 from the second flow path C2 toward the first fin 11a.

[0034] With this configuration, the second refrigerant flow F2, which has a faster flow velocity than the first refrigerant flow F1, sequentially collides with the first fin 11a and the second fin 11b, causing it to meander repeatedly and proceed to the downstream ends 11ab and 11bb of the first and second fins 11a and 11b. The meandering of the second refrigerant flow F2 disturbs the flow of the first refrigerant flow F1, and the first refrigerant flow F1 proceeds downstream while being influenced by the meandering of the second refrigerant flow F2. The meandering of the second refrigerant flow F2, which has a faster flow velocity, actively causes the refrigerant to flow against the wall surfaces of the first and second fins 11a and 11b in the third flow path C3 as well. This improves the heat dissipation performance downstream of the heat sink 1, i.e., in the third flow path C3.

[0035] In this embodiment, the partition plate 12 is positioned closer to the second fin 11b than the center between the first fin 11a and the second fin 11b in a direction (left-right direction X) perpendicular to the extension direction of the first and second fins 11a, 11b.

[0036] With this configuration, the flow velocity of the second refrigerant flow F2 can be accelerated by the refrigerant flowing through the narrow second flow path C2, so that the flow velocity of the second refrigerant flow F2 through the second flow path C2 can be made faster than the flow velocity of the first refrigerant flow F1 through the first flow path C1.

[0037] In this embodiment, the distance d from the downstream end 12b of the partition plate 12 to the protrusion 13 and the width t from the partition plate 12 to the second fin 11b in the left-right direction X satisfy the relationship t≧d.

[0038] With this configuration, the second refrigerant flow F2 flowing out of the second flow path C2 flows toward the first fin 11a at a steeper angle due to the protrusions 13. This increases the meandering width of the second refrigerant flow F2 and the number of meanders. This increases the number of times the second refrigerant flow F2 collides with the first and second fins 11a and 11b, significantly enhancing heat transfer. This improves the heat dissipation performance downstream of the heat sink 1, i.e., in the third flow path C3.

[0039] In this embodiment, the protrusion amount h of the protrusion portion 13 from the second fin 11b in the left-right direction X, the width T between the first fin 11a and the second fin 11b, and the width t from the partition plate 12 to the second fin 11b satisfy the relationship T-t>h>t.

[0040] Claim 6: With this configuration, the second refrigerant flow F2 flowing out of the second flow path C2 hits the protrusions 13 in a substantially linear manner, corresponding to the width of the flow, causing it to flow at a steep angle toward the first fins 11a. Furthermore, because there is a gap between the protrusions 13 and the first fins 11a, corresponding to the width of the flow, the second refrigerant flow F2 passes smoothly between the protrusions 13 and the first fins 11a and flows downstream. This allows the second refrigerant flow F2 to properly meander. The increased number of times the second refrigerant flow F2 hits the first and second fins 11a, 11b significantly enhances heat transfer. This improves the heat dissipation performance downstream of the heat sink 1, i.e., in the third flow path C3.

[0041] In the above-described embodiment, the partition plate 12 extends downstream from the upstream ends 11aa and 11ba of the first and second fins 11a and 11b. However, the partition plate 12 may extend downstream from a position offset downstream from the upstream ends 11aa and 11ba of the first and second fins 11a and 11b, as long as the downstream end 12b of the partition plate 12 is located upstream of the downstream ends 11ab and 11bb of the first and second fins 11a and 11b. The range of the third flow path C3 can be varied depending on the position of the partition plate 12, thereby controlling the heat dissipation performance required downstream of the heat sink 1.

[0042] Second Embodiment A cooling device according to a second embodiment will be described with reference to Fig. 4. The cooling device according to the second embodiment differs from the first embodiment in that it includes a refrigerant separation plate. Below, a description of the configuration common to the first embodiment will be omitted, and the description will focus on the differences.

[0043] The refrigerant separation plate is provided between the axial flow fan 2 and the first and second fins 11a, 11b. The refrigerant separation plate is composed of first and second partition walls 15a, 15b and an inclined plate 16.

[0044] The first and second partition walls 15a, 15b are attached to the upstream ends 11aa, 11ba of the first and second fins 11a, 11b. Specifically, the first partition wall 15a is attached to the upstream end 11aa of the first fin 11a, and the second partition wall 15b is attached to the upstream end 11ba of the second fin 11b. The first and second partition walls 15a, 15b extend upstream in the refrigerant flow in parallel with the first and second fins 11a, 11b. In contrast, the inclined plate 16 is attached to the upstream end 12a of the partition plate 12. The inclined plate 16 extends upstream in the refrigerant flow while inclining so that the inclined plate 16 approaches the first partition wall 15a as it approaches the upstream side of the refrigerant flow.

[0045] With a refrigerant separation plate configured as described above, two flow paths Cu1, Cu2 through which the refrigerant flows are formed between the axial fan 2 and the first and second fins 11a, 11b. A first upstream flow path Cu1 connected to the first flow path C1 is formed between the first partition wall 15a and the inclined plate 16. The first upstream flow path Cu1 is configured so that its flow path width increases toward the downstream side. Similarly, a second upstream flow path Cu2 connected to the second flow path C2 is formed between the second partition wall 15b and the inclined plate 16. The second upstream flow path Cu2 is configured so that its flow path width decreases toward the downstream side.

[0046] According to the second embodiment, the refrigerant from the axial fan 2 branches into the first and second upstream flow paths Cu1 and Cu2 and flows through the first and second upstream flow paths Cu1 and Cu2 to the first and second flow paths C1 and C2. If the refrigerant flows from the axial fan 2 toward the first and second flow paths C1 and C2 without using a refrigerant separation plate, the refrigerant would have difficulty flowing through the second flow path C2, which has a narrow inlet. By providing a refrigerant separation plate, the inlet width of the second upstream flow path Cu2 is set wider than the inlet width of the second flow path C2, allowing the refrigerant from the axial fan 2 to flow smoothly through the second upstream flow path Cu2. Furthermore, as the refrigerant flows toward the second flow path C2, the flow path width of the second upstream flow path Cu2 narrows, accelerating the flow velocity of the refrigerant, and the accelerated refrigerant flows into the second flow path C2. The second upstream flow path Cu2 is paired with the first upstream flow path Cu1, which has a flow path width that increases toward the first flow path C1, so that the pressure loss in the first upstream flow path Cu1 and the second upstream flow path Cu2 is equivalent. This allows the flow rate of the refrigerant flowing into the second flow path C2 to be faster than the flow rate of the refrigerant flowing into the first flow path C1, while maintaining the same flow rate of the refrigerant flowing into the first flow path C1 and the second flow path C2.

[0047] As described above, the cooling device according to this embodiment further includes a refrigerant separation plate. The refrigerant separation plate is disposed between the axial fan 2 and the heat sink 1, and serves to branch the refrigerant from the axial fan 2 into the first and second flow paths C1 and C2, and accelerate the refrigerant toward the second flow path C2.

[0048] This configuration accelerates the refrigerant toward the second flow path C2 and allows the refrigerant to flow smoothly through the second flow path C2. Because the flow velocity of the refrigerant through the second flow path C2 can be made faster than the flow velocity of the refrigerant through the first flow path C1, the second refrigerant flow F2 can be made to meander appropriately. The number of times the second refrigerant flow F2 collides with the first and second fins 11a, 11b increases, significantly enhancing heat transfer. This improves the heat dissipation performance downstream of the heat sink 1, i.e., in the third flow path C3.

[0049] In this embodiment, the refrigerant separation plate is disposed between the axial fan 2 and the first and second fins 11 a, 11 b. However, as shown in Fig. 5, the partition plate 12 may be inclined relative to the first and second fins 11 a, 11 b, so that the partition plate 12 itself functions as a refrigerant separation plate.

[0050] Third Embodiment A cooling device according to a third embodiment will be described with reference to Fig. 6. The cooling device according to the third embodiment differs from the first embodiment in that it includes a micro-blower. Hereinafter, a description of the configuration common to the first embodiment will be omitted, and the description will focus on the differences.

[0051] The microblower 17 is provided in the second flow path C2 and draws in and discharges the refrigerant. The microblower 17 accelerates the second refrigerant flow F2 by flowing the refrigerant in the same direction as the refrigerant flow generated by the axial fan 2.

[0052] With this configuration, the microblower 17 accelerates the second refrigerant flow F2, thereby generating a flow in the second flow path C2 that is faster than the flow velocity of the first refrigerant flow F1 flowing through the first flow path C1. Furthermore, since the microblower 17 is an element that can be driven with a few volts, it can be used in combination with the drive power supply used for, for example, the axial flow fan 2. This allows the refrigerant flowing through the second flow path C2 to be accelerated while avoiding an increase in size of the cooling device due to the addition of a drive power supply.

[0053] Although the micro-blower 17 is exemplified in this embodiment, any device (flow velocity generating device) that accelerates the second refrigerant flow F2 is usable, and is not limited to a micro-blower. Furthermore, if the flow velocity generating device can generate a flow in the second flow path C2 that is faster than the flow velocity of the first refrigerant flow F1 flowing through the first flow path C1, the partition plate 12 may be disposed closer to the first fin 11a than the center between the first fin 11a and the second fin 11b.

[0054] 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.

[0055] REFERENCE SIGNS 1 heat sink 2 axial fan (refrigerant flow generating device) 10 base plate 11 fins 11a, 11b first fin, second fin 12 partition plate 13 protrusions 15a, 15b first partition, second partition 16 inclined plate 17 microblower (flow velocity generating device) C1, C2, C3 first flow path, second flow path, third flow path Cu1, Cu2 first upstream flow path, second upstream flow path

Claims

1. A cooling device comprising: a refrigerant flow generating device that generates a refrigerant flow; and a heat sink having first and second fins extending parallel to each other on a base plate thermally connected to an object to be cooled, the refrigerant flowing through a flow path between the first and second fins, wherein the heat sink has: a partition plate provided between the first and second fins and extending a length shorter than the first and second fins; and a protrusion provided on a wall surface of the second fin facing the first fin, wherein the flow velocity of the second refrigerant flowing through the second flow path between the second fin and the partition plate is faster than the flow velocity of the first refrigerant flowing through the first flow path between the first fin and the partition plate, and the protrusion is located downstream of the partition plate and changes the direction of the second refrigerant flowing from the second flow path towards the first fin.

2. A cooling device as described in claim 1, wherein the partition plate is positioned closer to the second fin than the center between the first fin and the second fin in a direction perpendicular to the extension direction of the first and second fins.

3. The cooling device according to claim 1 or 2, further comprising a refrigerant separation plate disposed between the refrigerant flow generating device and the heat sink, which branches the refrigerant from the refrigerant flow generating device into the first and second flow paths and accelerates the refrigerant toward the second flow path.

4. The cooling device according to claim 1, further comprising a flow velocity generating device provided in said second flow path for accelerating said second refrigerant flow.

5. A cooling device as described in claim 1 or 2, wherein the relationship t≧d is satisfied, where d is the distance from the downstream end of the partition plate to the protrusion in the extension direction of the first and second fins, and t is the width from the second fin to the partition plate in a direction perpendicular to the extension direction of the first and second fins.

6. A cooling device as described in claim 5, wherein, when the amount of protrusion of the protrusion from the second fin in a direction perpendicular to the extension direction of the first and second fins is h and the width between the first fin and the second fin is T, the relationship T-t>h>t is satisfied.

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