JP7546464B2 - Corrugated Heat Transfer Fins and Heat Sinks - Google Patents

Description

The present invention relates to a corrugated heat transfer fin and a heat sink.

The following Patent Document 1 discloses a heat transfer tube for a heat exchanger. As shown in FIG. 1 etc., this heat transfer tube for a heat exchanger is a flat tube with a corrugated fin structure attached to the inner peripheral surface. This corrugated fin structure has a curved surface with a channel-shaped corrugation having a substantially rectangular cross-sectional shape and a corrugated undulation formed at a predetermined wavelength in the longitudinal direction, and when the wave width of the channel shape is H, the wavelength of the undulation in the longitudinal direction is L, and the amplitude of the undulation in the longitudinal direction is A, H/L is 0.17 to 0.20, and the ratio (G/H) of the gap G to H calculated by H-A is -0.21 to 0.19.

The following Patent Document 2 discloses a heat exchanger and a corrugated fin. As shown in FIG. 3 and other figures, the corrugated fins in Patent Document 2 are bent to form a wave shape between multiple tubes aligned in one direction, and promote heat exchange between a first fluid flowing inside the tubes and a second fluid flowing between the tubes.

More specifically, the corrugated fin of Patent Document 2 includes a plurality of joints that are joined to the tube, and a plurality of fin body sections that are connected to the respective joints so as to connect adjacent joints along the corrugated shape. The fin body section has a cut-and-raised section that is partially cut and raised, and the cut-and-raised section has a cut-and-raised main section that guides the second fluid, and a cut-and-raised end section that is plate-shaped and extends from the cut-and-raised main section and is provided at least at one end of the cut-and-raised section in one direction, and has an uneven shape formed to enhance the hydrophilicity of the surface of the cut-and-raised end section on at least one side in the plate thickness direction of the cut-and-raised end section.

JP 2007-078194 A JP 2019-211115 A

The corrugated fin structure (wave-shaped heat transfer fin) of Patent Document 1 can be said to be a corrugated fin, and by optimizing the relationship between wave width H, undulation wavelength L, and undulation amplitude A, the high-temperature exhaust gas flowing through the exhaust gas flow passage flows with a uniform flow velocity distribution, and heat exchange with the cooling medium flowing outside the heat transfer tube is promoted. In addition, the corrugated fin of Patent Document 2 has cut-and-raised portions in the fin body, which promotes heat transfer between the first and second fluids.

Here, by providing the cut-and-raised portions of Patent Document 2 to the corrugated fin structure of Patent Document 1, it is possible to promote heat transfer between the exhaust gas and the cooling medium in the corrugated fin structure of Patent Document 1. However, in a structure in which cut-and-raised portions are formed in the corrugated fin structure, the refrigerant flows on both the inside and outside of the corrugated fin structure, making it difficult for turbulent refrigerant to occur.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide a corrugated heat transfer fin and heat sink in which turbulence in the refrigerant is more likely to occur than in the past.

To achieve the above object, the present invention employs, as a first solution for a corrugated heat transfer fin, a corrugated heat transfer fin having a predetermined dimension in a first direction, a corrugated flow surface forming undulations of a predetermined period along a second direction perpendicular to the first direction, through which a fluid flows, the undulations being formed by alternatingly connecting straight sections oriented in different directions in the second direction, and each of the straight sections being provided with a recess or protrusion in the first direction.

The present invention adopts a second solution for the corrugated heat transfer fin, which is the first solution described above, in which the protrusions and the recesses have corners.

The present invention employs a third solution relating to a corrugated heat transfer fin as described in the first or second solution above, in which the protrusions and the recesses are triangular prisms with one side on the upstream side in the flow direction of the fluid and the other two sides on the downstream side in the flow direction.

The present invention employs a fourth solution relating to a corrugated heat transfer fin, which is the first or second solution, in which the protrusions and the recesses are triangular pyramid-shaped with their apex facing upstream in the direction of fluid flow and their bottom facing downstream in the direction of fluid flow.

The present invention employs a fifth solution relating to the corrugated heat transfer fins in any of the first to fourth solutions above, in which the fins are provided in the refrigerant flow path inside the heat sink.

The present invention employs a solution relating to the heat sink that includes a wave-shaped heat transfer fin according to any one of the first to fifth solutions described above.

The present invention provides a corrugated heat transfer fin and heat sink that are more likely to generate turbulent refrigerant flow than conventional heat transfer fins and heat sinks.

1 is a perspective view showing an exploded structure of a heat sink A in one embodiment of the present invention. 1A and 1B are a front view and a side view showing the shape of corrugated fins 3A and 3B (wave-shaped heat transfer fins) according to one embodiment of the present invention. 5A and 5B are a side view and a cross-sectional view showing the shapes of a recess 3i and a protrusion 3j in one embodiment of the present invention. 13A and 13B are a side view and a cross-sectional view showing the shapes of a recess 3i' and a protrusion 3j' in a first modified example of an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, the structure of the heat sink A in this embodiment will be described with reference to Fig. 1. In Fig. 1, three mutually perpendicular axes (X-axis, Y-axis, and Z-axis) are added to clarify the directions. Among the directions along these three axes, the direction parallel to the Z-axis corresponds to the first direction of the present invention, and the direction parallel to the Y-axis corresponds to the second direction of the present invention.

This heat sink A is a component of a PCU (Power Control Unit) that is installed in an electric vehicle and has multiple semiconductor switching transistors, and is attached to the underside of the PCU body. This heat sink A is also a mechanical part that dissipates heat from the multiple semiconductor switching transistors that generate heat in relation to switching power.

As is well known, the PCU is a power converter (such as a step-up/step-down converter or inverter) that drives the traction motor installed in an electric vehicle. It converts DC power supplied from a high-voltage power source such as a lithium-ion battery into AC power using multiple semiconductor switching transistors and outputs the AC power to the traction motor.

The heat sink A in this embodiment is intended to dissipate heat generated by multiple semiconductor switching transistors (semiconductor chips) in such a PCU to the outside, and as shown in FIG. 1, includes an upper cover 1, a lower cover 2, two corrugated fins 3A and 3B (wave-shaped heat transfer fins), a stay 4, a first connecting member 5A, and a second connecting member 5B.

Of the upper cover 1, lower cover 2, two corrugated fins 3A and 3B, and stay 4, the upper cover 1 and lower cover 2 are mechanical parts that make up the housing of the heat sink A. This housing contains a roughly rectangular fluid flow passage R, as described below.

That is, the upper cover 1 is a flat, approximately rectangular member, and its top surface is a flat chip bonding surface 1a to which the semiconductor chip is thermally bonded. The lower surface of the upper cover 1, i.e., the back surface of the chip bonding surface 1a, is a flat cover bonding surface 1b to which the lower cover 2 is bonded.

The upper cover 1 has a total of eight screw holes 1c-1j as shown in the figure. Of these eight screw holes 1c-1j, four screw holes 1c-1f are discretely arranged near the outer periphery of the upper cover 1. These four screw holes 1c-1f are for fixing the heat sink A to the PCU body, and a fixing screw (not shown) is inserted into each of them.

Of the remaining four screw holes 1g to 1j, two screw holes 1g and 1h are arranged as a pair near one of a pair of short sides of the upper cover 1. These two screw holes 1g and 1h are for fixing the first connection member 5A, and a fixing screw (not shown) is inserted into each of them.

The remaining two screw holes 1i, 1j are arranged as a pair near the other short side of the upper cover 1. These two screw holes 1i, 1j are for fixing the second connection member 5B, and a fixing screw (not shown) is inserted into each of them.

The lower cover 2 is a roughly rectangular flat member whose peripheral edge rises a predetermined distance in the Z-axis direction, and is joined in a state where the tip of the peripheral edge, i.e., the rising portion, abuts against the cover joining surface 1b of the upper cover 1. The housing of the heat sink A formed by such upper cover 1 and lower cover 2 is a hollow housing with a roughly rectangular cavity (refrigerant flow path R) formed inside.

That is, the upper surface of the lower cover 2 is a flow path forming surface 2a that forms the bottom surface of the refrigerant flow path R, and the lower surface is a fixing surface 2b. Note that, among the cover joint surface 1b of the upper cover 1 described above, the area surrounded by the rising portion of the lower cover 2 is the flow path forming surface that forms the top surface of the refrigerant flow path R when facing the flow path forming surface 2a of the lower cover 2 in the first direction.

The refrigerant flow path R formed by such upper cover 1 and lower cover 2 has a short side direction parallel to the X axis, a long side direction parallel to the X axis, and a height direction parallel to the Z axis. In addition, such a fluid flow path R has a volume determined by the short side dimensions, long side dimensions, and height dimensions.

The lower cover 2 is also provided with a fluid inlet 2c and a fluid outlet 2d. The fluid inlet 2c is provided near one short side of the substantially rectangular lower cover 2, and is an opening through which the liquid refrigerant flows into the refrigerant flow path R. The fluid outlet 2d is provided near the other short side of the substantially rectangular lower cover 2, and is an opening through which the liquid refrigerant flows out of the refrigerant flow path R.

That is, in the heat sink A of this embodiment, the liquid refrigerant enters the refrigerant flow path R from the fluid inlet 2c, flows through the refrigerant flow path R toward the fluid outlet 2d located at the position farthest from the fluid inlet 2c, and then flows out from the fluid inlet 2c to the outside. Such liquid refrigerant is heated by the heat of the multiple semiconductor chips while flowing through the refrigerant flow path R.

The two corrugated fins 3A, 3B are rectangular members having a certain height as shown in the figure, and both are formed in the same shape. These corrugated fins 3A, 3B are stored next to each other in the refrigerant flow path R. In other words, the upper surfaces of the two corrugated fins 3A, 3B in FIG. 1 are fixed to the flow path forming surface of the upper cover 1 by brazing or the like.

Here, in the corrugated fins 3A and 3B, the height direction (Z-axis direction) corresponds to the first direction of the present invention, and the long side direction (Y-axis direction) corresponds to the second direction of the present invention. That is, the two corrugated fins 3A and 3B are stored in the fluid flow passage R with their long sides parallel to the long side direction (Y-axis direction) of the fluid flow passage R, which is also formed in a rectangular shape, and adjacent to each other in the short side direction (X-axis direction) of the refrigerant flow passage R.

Next, the detailed shape of the corrugated fins 3A and 3B will be described with reference to Figure 2. These two corrugated fins 3A and 3B are press-molded products formed into a corrugated (wave-like) shape by pressing a metal sheet (base material), and are a continuation of multiple parallel wave portions 3a. The multiple wave portions 3a protrude from the flow passage forming surface 2a of the lower cover 2 toward the upper cover 1 at a predetermined dimension D and a predetermined interval E. In other words, the corrugated fins 3A and 3B have a predetermined dimension D in the Z-axis direction (first direction), which is the height direction.

As shown in the figure, the multiple wave portions 3a undulate at a predetermined period T along the long side direction (Y axis direction, second direction) perpendicular to the height direction (Z axis direction, first direction). That is, the corrugated fins 3A and 3B have undulations at a predetermined period T formed along the long side direction (Y axis direction, second direction) perpendicular to the height direction (Z axis direction, first direction) by the wave-shaped wave portions 3a.

As shown in the figure, the swell is formed in a shape in which straight line sections 3b of different orientations are alternately connected. In other words, the swell has a shape in which the wave sections 3a extending in the long side direction (Y-axis direction, second direction) are bent in the short side direction (X-axis direction), in other words, straight line sections 3b whose bending direction is opposite to the long side direction (Y-axis direction, second direction) are alternately connected in the long side direction (Y-axis direction, second direction).

The above undulations are arranged so that all of the waves 3a have the same phase in the long side direction (Y-axis direction, second direction). That is, in the corrugated fins 3A and 3B, the spacing between adjacent waves 3a is kept approximately constant at all points in the long side direction (Y-axis direction, second direction).

The multiple waves 3a are arranged in the short side direction (X-axis direction) of the corrugated fins 3A, 3B, and extend in the long side direction (Y-axis direction) of the corrugated fins 3A, 3B. When the corrugated fins 3A, 3B are housed in the refrigerant flow path R, the tops 3d of the multiple waves 3a are brazed to the flow path forming surface of the upper cover 1, as shown in FIG. 2, and the bottoms 3c are in contact with the flow path forming surface 2a of the lower cover 2.

In addition, in each of the multiple waves 3a, one end is a refrigerant inlet end 3e facing the fluid inlet 2c of the lower cover 2, and the other end is a refrigerant outlet end 3f facing the fluid outlet 2d of the lower cover 2. In other words, in each of the multiple waves 3a, one end (refrigerant inlet end 3e) is located near the fluid inlet 2c, and the other end (refrigerant outlet end 3f) is located near the fluid outlet 2d.

In such a heat sink A, the liquid refrigerant that flows into the refrigerant flow path R from the fluid inlet 2c enters the multiple waves 3a from the refrigerant inlet end 3e, flows through the front surface, i.e., the first flow surface 3g, and the back surface, i.e., the second flow surface 3h, of the multiple waves 3a, and reaches the fluid outlet 2d via the refrigerant outlet end 3f.

That is, the above-mentioned refrigerant flow path R consists of a first refrigerant flow path R1 surrounded by the first flow surface 3g and the flow path forming surface of the upper cover 1, and a second refrigerant flow path R2 surrounded by the second flow surface 3h and the flow path forming surface 2a of the lower cover 2.

Here, FIG. 3 shows a side view (a) of two adjacent straight portions 3b and a cross-sectional view (b) of the side view in the X-Y plane. As shown in FIG. 3, on both sides (both sides in the X-axis direction) of each straight portion 3b, recessed portions 3i or protrusions 3j are provided in part of the straight portion, not in the entire height direction (Z-axis direction, first direction).

That is, in the multiple wavy sections 3a that face each other in parallel in the long side direction (Y-axis direction) and extend in the long side direction (Y-axis direction, second direction), recessed sections 3i or protrusions 3j are formed alternately on both sides of each straight section 3b (both sides in the X-axis direction). More specifically, recessed sections 3i are formed on both sides of a certain straight section 3b, and protrusions 3j are formed on both sides of the straight section 3b adjacent to that straight section 3b.

Of these recessed portions 3i and protrusions 3j, recessed portion 3i has a corner portion 3k and a corner portion 3m as shown in FIG. 3, and has a predetermined step (depth) corresponding to the distance between said corner portion 3k and said corner portion 3m. Such corner portion 3k and corner portion 3m have an angle of approximately 90°, and the surface (connecting surface 3n) connecting corner portion 3k and corner portion 3m is flat. Note that corner portion 3k and corner portion 3m in this recessed portion 3i correspond to the other two side edges in the present invention.

Such a recess 3i is shaped into a generally triangular prism with one side 3p located upstream in the fluid flow direction and corner 3k and corner 3m (the other two sides) located downstream in the fluid flow direction. That is, the shape of the recess 3i in this embodiment is such that, in the long side direction (Y-axis direction) of the corrugated fins 3A, 3B, one side 3p is located on the refrigerant inflow end 3e side, and corner 3k and corner 3m (the other two sides) are located on the refrigerant outflow end 3f side.

As shown in FIG. 3, the protrusion 3j has a corner 3q and a corner 3r, and has a predetermined step (depth) corresponding to the distance between the corner 3q and the corner 3r. The corner 3q and the corner 3r of the protrusion 3j have an angle of approximately 90°, and the surface (connection surface 3s) connecting the corner 3q and the corner 3r is flat. The corner 3q and the corner 3r of the protrusion 3j correspond to the other two side edges in the present invention.

Such a recess 3i is shaped into a substantially triangular prism with one side 3t located downstream in the fluid flow direction and corner 3q and corner 3r (the other two sides) located upstream in the fluid flow direction. That is, the shape of the recess 3i in this embodiment is such that, in the long side direction (Y-axis direction) of the corrugated fins 3A, 3B, one side 3t is located on the refrigerant inflow end 3e side, and corner 3q and corner 3r (the other two sides) are located on the refrigerant outflow end 3f side.

The recesses 3i and protrusions 3j in each wave portion 3a function as separation portions that cause a separation phenomenon in the liquid refrigerant flowing on the first flow surface 3g from the refrigerant inlet end 3e to the refrigerant outlet end 3f, because the connection surfaces 3n and 3s are oriented in a direction opposite to the flow of the liquid refrigerant. That is, the recesses 3i and protrusions 3j in each wave portion 3a agitate the liquid refrigerant based on the above-mentioned separation phenomenon, causing the liquid refrigerant to flow as a turbulent flow rather than a laminar flow in the first refrigerant flow path R1.

Meanwhile, the stay 4 shown in FIG. 1 is a plate-like member for fixing the housing to the PCU body, and has a total of four screw holes 4a-4d. The top surface of this stay 4 is joined to the fixing surface 2b (bottom surface) of the lower cover 2. The stay 4 is also fixed to the PCU body by fixing screws (not shown) inserted into its own screw holes 4a-4d and into the four screw holes 1c-1f in the upper cover 1. In other words, the upper cover 1 and stay 4 are fixed to the PCU body by being fastened together with the fixing screws.

The first connecting member 5A is a generally disk-shaped member with an opening 5a in the center and screw holes 5b, 5c at two locations on the periphery, sandwiching the opening 5a. This first connecting member 5A is a connector for connecting an external pipe that supplies liquid refrigerant to the heat sink A to the fluid inlet 2c of the lower cover 2.

The second connection member 5B is a generally disk-shaped member with an opening 5d in the center and screw holes 5e and 5f at two locations on the periphery, sandwiching the opening 5d. This second connection member 5B is a connector for connecting an external pipe that discharges the liquid refrigerant from the heat sink A to the fluid outlet 2d of the lower cover 2.

Next, the effects of the heat sink A configured in this manner, and in particular the effects of the corrugated fins 3A and 3B (wave-shaped heat transfer fins) according to this embodiment, will be described in detail.

As described above, in the heat sink A of this embodiment, multiple semiconductor chips (heat-generating components) are thermally bonded to the chip bonding surface 1a of the upper cover 1. That is, heat generated by the multiple semiconductor chips is transferred to the upper cover 1 of the heat sink A. Then, the heat from the semiconductor chips is transferred to the two corrugated fins 3A and 3B housed in the refrigerant flow path R of the heat sink A.

The heat of the semiconductor chip transferred to the corrugated fins 3A and 3B is then transferred to the liquid refrigerant flowing through the refrigerant flow path R, heating the liquid refrigerant. Since the liquid refrigerant flows from the fluid inlet 2c of the lower cover 2 to the fluid outlet 2d, that is, flows through the refrigerant flow path R, the heat of the semiconductor chip transferred to the corrugated fins 3A and 3B is sequentially transferred to the liquid refrigerant, suppressing the temperature rise of the semiconductor chip.

The corrugated fins 3A and 3B have recesses 3i or protrusions 3j in the straight line portions 3b that make up the corrugated portion 3a, respectively, and therefore have improved heat transfer performance compared to when the recesses 3i and protrusions 3j are not provided. In other words, the corrugated fins 3A and 3B according to this embodiment have superior heat transfer performance compared to those that do not have the recesses 3i and protrusions 3j.

These two corrugated fins 3A, 3B are formed by pressing a metal plate (base material) to have recesses 3i and protrusions 3j, and the recesses 3i and protrusions 3j can be formed very easily. In other words, this embodiment can provide corrugated fins 3A, 3B (wave-shaped heat transfer fins) and a heat sink A in which turbulence in the refrigerant is more likely to occur than in the past.

In addition, according to this embodiment, since the recess 3i has a corner 3m and the protrusion 3j has a corner 3r, and since the recess 3i and the protrusion 3j are shaped to have a substantially triangular prism shape, the turbulence can be generated more effectively than when the recess 3i and the protrusion 3j do not have the corners 3m and 3r, or when the recess 3i and the protrusion 3j are not shaped to have a substantially triangular prism shape.

The present invention is not limited to the above-described embodiment, and the following modifications are possible.
(1) In the above embodiment, the recess 3i and the protrusion 3j are substantially triangular prism shaped, but the present invention is not limited to this. The recess 3i and the protrusion 3j may have other shapes as long as they can generate turbulent flow. For example, a modified example of the recess 3i and the protrusion 3j may be a recess 3i' and a protrusion 3j' shown in FIG. 4.

The recess 3i' in FIG. 4 is a generally triangular pyramid shape with the apex 3u on the upstream side in the direction of fluid flow and the bottom surface 3x on the downstream side in the direction of fluid flow. The protrusion 3j' is a generally triangular pyramid shape with the apex 3v on the downstream side in the direction of fluid flow and the bottom surface 3w on the upstream side in the direction of fluid flow. In this modified example, the bottom surfaces 3x and 3w are oriented opposite the flow of the liquid refrigerant, so that the liquid refrigerant can be effectively turbulent.

(2) In the above embodiment, the recesses 3i or protrusions 3j are provided on both sides (both sides in the X-axis direction) of each straight portion 3b, but the present invention is not limited to this. The recesses 3i or protrusions 3j may be provided on one side of each straight portion 3b. When the recesses 3i or protrusions 3j are provided on one side of each straight portion 3b, it is preferable to provide the recesses 3i or protrusions 3j so that the recesses 3i or protrusions 3j are present on one of a pair of opposing surfaces formed by adjacent wave portions 3a in the X-axis direction.

(3) In the above embodiment, the recesses 3i and the protrusions 3j are alternately provided in the wavy portion 3a in which the multiple straight portions 3b are connected in the long side direction (Y-axis direction, second direction), but the present invention is not limited to this. For example, in the long side direction (Y-axis direction, second direction), recesses 3i may be provided in a predetermined number of consecutive straight portions 3b, and protrusions 3j may be provided in a predetermined number of straight portions 3b consecutive to the predetermined number of straight portions 3b. In other words, recesses 3i and protrusions 3j may be alternately provided for each of the multiple straight portions 3b.

(4) In the above embodiment, two corrugated fins 3A, 3B are housed in the refrigerant flow path R, but the present invention is not limited to this. For example, two corrugated fins 3A, 3B may be integrated together, that is, a single corrugated fin may be housed in the refrigerant flow path R.

(5) In the above embodiment, two corrugated fins 3A, 3B are arranged in the X-axis direction, but the present invention is not limited to this. For example, multiple corrugated fins with a relatively short length in the Y-axis direction may be arranged in the Y-axis direction. In this case, the liquid refrigerant flows around the corrugated fins located sequentially from the upstream side to the downstream side.

When arranging multiple corrugated fins in the Y-axis direction in this manner, it is preferable to leave a gap between adjacent corrugated fins in the Y-axis direction. In other words, when adjacent corrugated fins are spaced apart in the Y-axis direction, the liquid refrigerant that flows around the upstream corrugated fin is subjected to a separation action by the upstream end of the downstream corrugated fin. Since this separation action occurs in each of the multiple corrugated fins, it is possible to more effectively turbulently flow the liquid refrigerant.

A Heat sink R1 First refrigerant flow path R2 Second refrigerant flow path 1 Upper cover 1a Chip bonding surface 1b Cover bonding surface 1c to 1j, 4a to 4d, 5c to 5f Screw holes 2 Lower cover 2a Flow path forming surface 2b Fixing surface 2c Fluid inlet 2d Fluid outlet 3A, 3B Corrugated fins (wave-shaped heat transfer fins)
3a Wave part 3b Straight part 3c Bottom part 3d Top part 3e Refrigerant inflow end 3f Refrigerant outflow end 3g First circulation surface 3h Second circulation surface 3i Recessed part 3j Projection part 3k, 3q Corner part 3m, 3r Corner part 3n, 3s Connection surface 3p, 3t 1 side 3u, 3v Vertex 3x, 3 w Bottom surface 4 Stay 5A First connection member 5B Second connection member 5a, 5b Opening

Claims (5)

A corrugated heat transfer fin having a predetermined dimension in a first direction, a corrugated flow surface forming a undulation having a predetermined period along a second direction perpendicular to the first direction, and a fluid flowing through the flow surface,
The undulation has a shape in which straight line portions oriented in different directions in the second direction are alternately connected,
Each of the linear portions is provided with a recess or a protrusion in the first direction ,
A corrugated heat transfer fin characterized in that the protrusions and the recesses have a triangular prism shape with one side facing upstream in the flow direction of the fluid and the other two side sides facing downstream in the flow direction . A corrugated heat transfer fin having a predetermined dimension in a first direction, a corrugated flow surface forming a undulation having a predetermined period along a second direction perpendicular to the first direction, and a fluid flowing through the flow surface,
The undulation has a shape in which straight line portions oriented in different directions in the second direction are alternately connected,
Each of the linear portions is provided with a recess or a protrusion in the first direction ,
A corrugated heat transfer fin characterized in that the protrusions and the recesses have a triangular pyramid shape with their tops on the upstream side in the flow direction of the fluid and their bottoms on the downstream side in the flow direction . The corrugated heat transfer fin according to claim 1 , wherein the protrusions and the recesses have corners . 4. The corrugated heat transfer fin according to claim 1, wherein the corrugated heat transfer fin is provided in a refrigerant flow path in a heat sink . A heat sink comprising the corrugated heat transfer fin according to any one of claims 1 to 4.

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