Boiling type cooler and manufacturing method of boiling type cooler

Abstract

The boiling-type cooler (100) is provided with: a boiling unit (10) that boils a refrigerant (5) by heat exchange with a heating element (HS); and a condensing unit (20) that condenses the refrigerant vaporized in the boiling unit and returns the condensed refrigerant to the boiling unit. The boiling section includes a mounting surface (11a) for the heating element, and a boiling surface section (13) that is provided on a surface (11b) on the opposite side from the mounting surface and that is in contact with the refrigerant. The boiling surface portion includes a groove portion (14) extending in a linear shape and having an irregular concave-convex shape formed as a result of melting and solidification of the material due to energy beam processing.

Description

Technical Field

[0001] The present invention relates to a boiling cooler and a method for manufacturing the boiling cooler, and in particular to a boiling cooler having a boiling section for boiling a refrigerant and a condensing section for condensing the refrigerant and returning it to the boiling section, and a method for manufacturing the boiling cooler. Background Art

[0002] Conventionally, there is known an ebullient cooler having a boiling section for boiling a refrigerant and a condensing section for condensing the refrigerant and returning it to the boiling section. This ebullient cooler is disclosed in, for example, Japanese Patent Application Publication No. 2016-114304.

[0003] The above-mentioned Japanese Patent Publication No. 2016-114304 discloses a boiling cooling device (boiling cooler), which includes a heat receiving part (boiling part) for boiling the refrigerant and a heat dissipation part (condensing part) for condensing the refrigerant and returning it to the heat receiving part. The heat receiving part includes a heating element mounting part for mounting the cooling object and a boiling heat transfer surface arranged on the back of the heating element mounting part. The boiling heat transfer surface has a plurality of holes whose inner peripheral surface becomes a rough surface by irradiating a laser beam to an aluminum plate-like raw material, and an annular protrusion formed around the opening of each hole. The plurality of holes are open in the boiling heat transfer surface and have a circular shape with an inner peripheral surface and a bottom. The annular protrusion is formed as follows: droplets of molten aluminum generated by irradiating the aluminum plate-like raw material with a high-energy beam splash and adhere to the periphery of the hole, and the droplets solidify and stack, thereby forming an annular protrusion.

[0004] In the above-mentioned Japanese Patent Publication No. 2016-114304, the heat generated by the heating element is transferred to the refrigerant via the boiling heat transfer surface, and the liquid phase refrigerant boils and vaporizes to become gaseous in the portion in contact with the boiling heat transfer surface, and bubbles are generated on the boiling heat transfer surface and released into the liquid phase refrigerant. The above-mentioned Japanese Patent Publication No. 2016-114304 states the following: Since the surface is a rough surface, the generation rate of bubbles is increased on the inner peripheral surface of the hole and the surface of the annular protrusion, and the surface of the boiling heat transfer surface is not easily covered by the vapor film through the annular protrusion, so the occurrence of burnout can be delayed.

[0005] Previous technical literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-114304

[0008] Summary of the Invention

[0009] Technical issues to be solved by the invention

[0010] However, in the above-mentioned Japanese Patent Gazette No. 2016-114304, the generation rate of bubbles inside the hole is increased, and on the other hand, the liquid-phase refrigerant can only enter the inside of the hole through the opening. Moreover, since the opening of the hole is surrounded by an annular protrusion, it becomes a structure in which the liquid-phase refrigerant is not easy to flow into the opening. Therefore, when the bubbles are released from the inside of the hole, the liquid-phase refrigerant outside the hole is difficult to be smoothly supplied to the inside of the hole. Therefore, the inside of the hole is continuously filled with bubbles and easily becomes a dry state (dryout). It is believed that the inside of the hole is easy to dry out, especially under the condition of large heat input (heat flux density) per unit time. If the inside of the hole becomes a dry state, it will become the main reason for the decrease in thermal conductivity of the boiling heat transfer surface. Therefore, it is expected to increase the generation rate of bubbles by forming concave and convex, and to suppress the occurrence of local drying out.

[0011] The present invention is completed to solve the above-mentioned problems. One of the purposes of the present invention is to provide a boiling cooler and a method for manufacturing a boiling cooler that can improve the bubble generation rate by forming projections and depressions on the boiling surface and can inhibit local drying.

[0012] Means for solving technical problems

[0013] In order to achieve the above-mentioned purpose, the boiling cooler involved in the first invention comprises a boiling section for boiling the refrigerant through heat exchange with the heat generating body and a condensing section for condensing the refrigerant vaporized in the boiling section and returning it to the boiling section, the boiling section includes a mounting surface of the heat generating body and a boiling surface section which is arranged on the side opposite to the mounting surface and contacts the refrigerant, the boiling surface section includes a groove section which extends linearly and has an irregular concave-convex shape formed by the melting and solidification of the material due to energy beam processing.

[0014] In addition, "energy beam" is a broad concept that includes, for example, laser beams, electron beams, and ion beams, which are particles with energy focused into a beam shape. "Irregular concave-convex shapes formed with the melting and solidification of materials due to energy beam processing" means that the groove processing of removing materials by irradiating the surface of the material constituting the boiling surface with an energy beam, as a result of the material rapidly melting and / or evaporating due to the temperature rise generated on the surface of the material, the molten and / or evaporated material splashing, and the splashed material stacking up afterwards, irregularly forming concave-convex shapes unique to energy beam processing on the boiling surface.

[0015] In the boiling cooler involved in the first invention, as described above, the boiling surface includes a groove portion that extends in a linear shape and has an irregular concave-convex shape formed by the melting and solidification of the material due to the energy beam processing. Thus, the irregular concave-convex groove portion formed on the boiling surface becomes the starting point of nucleate boiling, thereby increasing the rate of bubble generation. Moreover, since the concave-convex shape is not a hole surrounded by the periphery, but a groove portion extending in a linear shape, no barrier is formed at least in the extension direction of the groove portion, and liquid-phase refrigerant can flow. That is, since a pair of inner side surfaces are formed in the width direction of the groove portion, the rate of bubble generation can be increased by greatly ensuring the heat transfer area for the liquid-phase refrigerant, and since no inner side surfaces are formed in the extension direction of the groove portion, the liquid-phase refrigerant can be smoothly supplied from the outside of the groove portion to the inside of the groove portion as the generated bubbles detach from the groove portion. As a result, the rate of bubble generation can be increased by forming concave-convex on the boiling surface, and local drying can be suppressed.

[0016] In the first invention, the groove portion preferably includes a space portion, which is composed of at least one of a hole portion opening in the boiling face portion, a hollow portion in which at least a part of the opening portion in the hole portion is covered, a horizontal hole portion extending laterally from the hole portion or the hollow portion, and a tunnel-shaped portion in which a part of the opening of the groove portion is covered. In addition, the "hole portion opening in the boiling face portion" refers to a local hole (recessed portion) surrounded by the entire circumference of the inner surface of the groove portion and the portion open (opening) at the upper end. The "hollow portion" refers to a portion in which a part or all of the opening portion of the hole formed by the energy beam is covered due to the stacking of materials splashed by the irradiation of the energy beam. The "horizontal hole portion" refers to a space portion formed in a manner of being recessed to the side different from the depth direction of the groove portion (i.e., the irradiation direction of the energy beam) due to the rapid expansion of the material generated by the irradiation of the energy beam. The tunnel-shaped portion refers to a space portion in which a part of the opening of the groove portion (a part of the length direction of the groove portion) is covered in a roof-like manner due to the stacking of materials splashed by the irradiation of the energy beam, resulting in a tunnel-shaped space portion. By forming such a groove portion including a space portion in a concavo-convex shape, a portion that becomes the starting point of nucleate boiling can be effectively formed on the boiling surface portion. As a result, the generation rate of bubbles in the boiling surface portion can be effectively increased.

[0017] In this case, preferably, the space portion is a structure partially formed in a part of the groove portion. By configuring in this way, a fine space portion suitable for generating bubbles can be provided in the groove portion as a partial structure of the groove portion.

[0018] In the first invention, preferably, at least a portion of the groove has a bottom whose width is wider than the opening width of the groove in a cross section perpendicular to the extending direction of the groove. By configuring in this way, the width of the internal space of the groove is greater than the opening width, and an internal space of a shape that surrounds the bubbles generated at the bottom of the groove from both sides to the opening is formed, thereby increasing the internal surface area (heat transfer area) of the groove. As a result, heat can be efficiently transferred to the refrigerant in the groove.

[0019] In the first invention, preferably, a plurality of grooves are formed on the boiling surface, and the plurality of grooves include a plurality of first grooves extending in a first direction along the boiling surface and a plurality of second grooves extending in a second direction different from the first direction along the boiling surface and intersecting with the plurality of first grooves. By configuring in this way, the first grooves extending in directions different from each other intersect with the second grooves, and therefore, for example, compared with a structure in which linear grooves are arranged in parallel, liquid-phase refrigerant can be more efficiently supplied in the extending direction of the grooves. As a result, local drying up in the grooves can be further effectively suppressed.

[0020] In this case, preferably, the boiling section has a connecting portion for allowing the refrigerant to circulate between the boiling section and the condensing section, the first direction is the direction from the boiling surface portion toward the connecting portion side in the boiling section, and the number of the first groove portions is greater than the number of the second groove portions. By configuring in this way, the flow direction of the refrigerant when the refrigerant circulates between the boiling section and the condensing section can be consistent with the first direction in which the large number of first groove portions extend. That is, the liquid-phase refrigerant returning from the condensing section to the boiling section flows from the connecting portion into the boiling section and moves to the position of the boiling surface portion in the boiling section, thereby forming a flow of the liquid-phase refrigerant in a direction substantially the same as the first direction. By providing a large number of first groove portions as main groove portions along the flow direction of the liquid-phase refrigerant, the liquid-phase refrigerant can be more effectively supplied to the first groove portion. As a result, local drying up in the groove portion can be further and more effectively suppressed.

[0021] In the above-mentioned first invention, preferably, the boiling surface portion includes a plurality of first regions in which grooves are formed and a second region which is arranged between the plurality of first regions and in which no grooves are formed. By configuring in this way, it is possible to set a first region in which the efficiency of bubble generation is relatively high on the boiling surface portion, and to set a second region in which the efficiency of bubble generation is relatively low and a large amount of liquid-phase refrigerant is present between the first regions. Thus, for example, in a situation where the heat flux is large and drying up is also likely to occur in the grooves formed in the first region, the effect of supplying liquid-phase refrigerant from the second region to the first region can be obtained. As a result, it is possible to suppress drying up in the grooves.

[0022] In this case, preferably, in the boiling surface, a plurality of first regions and a plurality of second regions are arranged alternately, and each of the plurality of first regions is formed in a stepped shape offset in the thickness direction of the boiling surface relative to the adjacent second region. By such a configuration, a relatively large groove-shaped or hole-shaped first structure is formed on the boiling surface through the adjacent first and second regions, and a relatively small groove-shaped second structure is formed on the surface of the first region in the first structure through the groove portion. Thus, compared with the case where only the second structure (groove portion) is provided on the flat boiling surface, the heat transfer area (surface area in contact with the liquid-phase refrigerant) of the boiling surface can be increased.

[0023] In the first invention, the groove preferably has a maximum opening width of 1 μm or more and less than 1 mm. By configuring in this way, a groove of a size suitable for the starting point of nucleate boiling in the liquid phase refrigerant can be provided. As a result, the generation rate of bubbles in the boiling surface can be effectively increased.

[0024] In the manufacturing method of the boiling type cooler involved in the second invention, the boiling type cooler includes a boiling section that boils the refrigerant through heat exchange with the heat generating body and a condensation section that condenses the refrigerant vaporized in the boiling section and returns it to the boiling section. The manufacturing method of the boiling type cooler includes the step of forming the condensation section and the step of forming the boiling section including a mounting surface of the heat generating body and a boiling surface section that is arranged on the side opposite to the mounting surface and contacts the refrigerant. The step of forming the boiling section includes performing groove processing by irradiating the boiling surface section with an energy beam in a linear pattern to form a groove section having an irregular concave-convex shape formed on the boiling surface section due to the melting and solidification of the material caused by the energy beam processing.

[0025] In the manufacturing method of the boiling cooler involved in the second invention, as described above, the process of forming the boiling portion includes the process of forming a groove portion with an irregular concave-convex shape formed on the boiling surface portion by irradiating the boiling surface portion with an energy beam in a linear pattern to perform groove processing, and forming a groove portion with an irregular concave-convex shape accompanied by the melting and solidification of the material caused by the energy beam processing on the boiling surface portion. Thus, the groove portion with an irregular concave-convex shape formed on the boiling surface portion becomes the starting point of nucleate boiling, thereby increasing the generation rate of bubbles. Moreover, since the concave-convex shape is not a hole surrounded by the periphery, but a groove portion extending in a linear shape, no barrier is formed at least in the extension direction of the groove portion, and liquid-phase refrigerant can be circulated. That is, since a pair of inner side surfaces are formed in the width direction of the groove portion, the generation rate of bubbles can be increased by greatly ensuring the heat transfer area for the liquid-phase refrigerant, and since no inner side surfaces are formed in the extension direction of the groove portion, the liquid-phase refrigerant can be smoothly supplied from the outside of the groove portion to the inside of the groove portion as the generated bubbles detach from the groove portion. As a result, the bubble generation rate can be increased by forming the irregularities on the boiling surface, and the occurrence of local drying can be suppressed.

[0026] Effects of the Invention

[0027] According to the present invention, as described above, the bubble generation rate can be increased by forming the irregularities on the boiling surface, and the occurrence of local drying can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic perspective view showing the boiling cooler according to the first embodiment.

[0029] Figure 2 It is a schematic exploded perspective view showing the boiling cooler according to the first embodiment.

[0030] Figure 3 It is a schematic longitudinal sectional view showing the boiling cooler according to the first embodiment.

[0031] Figure 4 It is a schematic top view showing the first example of the boiling surface.

[0032] Figure 5 It is a schematic plan view of the boiling part showing the position of the boiling surface part and the orientation of the groove part.

[0033] Figure 6 It is a schematic cross-sectional view (A) showing a processed image of a first example of a groove portion and a schematic cross-sectional view (B) showing a first example of a groove portion actually formed.

[0034] Figure 7 This is a schematic diagram for explaining the formation of projections and depressions by energy beam processing.

[0035] Figure 8 It is a schematic cross-sectional view showing the second example (A) and the modified example (B) of the groove portion.

[0036] Fig. 9 1 and 1. A plan view (A) and a schematic cross-sectional view (B) of a third example of a groove portion, and a plan view (C) and a schematic cross-sectional view (D) showing a modified example of the third example.

[0037] Fig.10 These are a plan view (A) of the hole portion, a PP cross-sectional view (B) of the hole portion, and a QQ cross-sectional view (C) of the hole portion involved in the comparison example, and a plan view (D) of the groove portion, a PP cross-sectional view (E) of the groove portion, and a QQ cross-sectional view (F) of the groove portion involved in the first embodiment.

[0038] Fig.11 It is an explanatory diagram of the process of forming the condensation section.

[0039] Fig.12 It is an explanatory diagram of the process of forming the boiling part.

[0040] Fig.13 This is an illustration for explaining the process of joining the boiling section and the condensing section and installing the heating element on the mounting surface.

[0041] Fig.14 It is an explanatory diagram of a first modified example of the formation pattern of the groove portion.

[0042] Fig.15 It is an explanatory diagram of a second modified example of the formation pattern of the groove portion.

[0043] Fig.16 This is a schematic exploded perspective view showing a boiling cooler according to a first modification of the first embodiment.

[0044] Fig.17 It is a schematic exploded perspective view showing a boiling cooler according to a second modification of the first embodiment.

[0045] Fig.18 It is a schematic perspective view showing a boiling cooler according to a second embodiment.

[0046] Fig.19 This is a schematic exploded perspective view (1) showing a boiling section of a boiling cooler according to a second embodiment.

[0047] Fig. 20 This is a schematic exploded perspective view (2) showing a boiling section of a boiling cooler according to a second embodiment.

[0048] Fig.21 It is a diagram for explaining how the mounting portion of the ebullient cooler according to the second embodiment is mounted on the evaporator body.

[0049] Fig. 22 This is a diagram for explaining how the evaporation section of the boiling cooler according to the second embodiment is mounted on the condensation section.

[0050] Fig.23 It is a diagram for explaining a state where a heat generating element is attached to the boiling cooler according to the second embodiment.

[0051] Fig.24 This is a schematic exploded perspective view showing an evaporation portion of an ebullient cooler according to a first modification of the second embodiment.

[0052] Fig.25 It is a schematic exploded perspective view showing an evaporation portion of an ebullient cooler according to a second modification of the second embodiment. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0054] [First embodiment]

[0055] refer to Figures 1 to 9 The structure of the boiling cooler 100 (hereinafter referred to as the cooler 100) according to the first embodiment will be described. The cooler 100 is a device that uses a refrigerant 5 (refer to Figure 3 A cooler based on boiling cooling method that absorbs heat from the heat generating element HS by utilizing the phase change (latent heat) of vaporization and condensation of the heat generating element HS and dissipates the heat to the outside. The heat generating element HS is, for example, a CPU (central processing unit). The heat generating element HS is not particularly limited. The refrigerant 5 is, for example, a fluorocarbon, a hydrocarbon, or water. The refrigerant 5 is not particularly limited.

[0056] Hereinafter, two directions substantially perpendicular to each other in a horizontal plane are respectively referred to as the X direction and the Y direction. The vertical direction substantially perpendicular to the horizontal plane (XY plane) is referred to as the Z direction. In addition, the Z direction is referred to as a direction parallel to the gravity direction and in which gravity acts downward.

[0057] like Figures 1 to 3 As shown, the cooler 100 includes a boiling section 10 and a condensing section 20. The boiling section 10 heats the refrigerant 5 (see Figure 3 ) boiling. The condensing section 20 condenses the refrigerant 5 vaporized in the boiling section 10 and returns it to the boiling section 10. The boiling section 10 and the condensing section 20 have airtight internal spaces that are interconnected, and the refrigerant 5 is accommodated in the internal spaces. In the first embodiment, the boiling section 10 and the condensing section 20 are integrated. That is, the boiling section 10 and the condensing section 20 are adjacent to (contacting) each other.

[0058] The boiling section 10 includes a mounting section 11 and a receiving section 12 (see Figure 3 The mounting portion 11 has a plate-like shape extending in the horizontal direction. The lower side (Z2 direction side) of the mounting portion 11 is the mounting surface 11a of the heating element HS. In the mounting portion 11, a boiling surface 13 is provided on the upper side (Z1 direction side) of the mounting surface 11b on the side opposite to the mounting surface 11a. The receiving portion 12 receives the refrigerant 5 in the liquid phase. Figure 3 As shown, the housing portion 12 is a concave component having a bottom portion 12a and a peripheral wall 12b and recessed downward (in the Z2 direction). The upper surface of the housing portion 12 is joined to the lower surface of the condensation portion 20. A hole portion 12d is provided on the bottom portion 12a, and the hole portion 12d is blocked by the mounting portion 11. The boiling surface portion 13 is configured on the surface 11b of the mounting portion 11 to be accommodated inside the hole portion 12d. In the housing portion 12, the boiling surface portion 13 is in contact with the liquid refrigerant 5. In addition, the details of the boiling surface portion 13 will be described later.

[0059] The condenser 20 is formed of a plate-fin heat exchanger and includes one or more refrigerant passages 21 and one or more external passages 22 . Figure 1 to Figure 3 In the example of FIG. 4 , four refrigerant channels 21 and five external channels 22 are provided in the condensing portion 20. Figure 3 As shown, the refrigerant channels 21 and the external channels 22 are alternately arranged in the Z direction via the partitions 23. Each refrigerant channel 21 is a hollow plate-shaped space extending in the X direction, and constitutes a part of the closed internal space of the cooler 100. The refrigerant channel 21 is a flow path for the refrigerant 5 to flow. Corrugated fins (not shown) extending in the X direction are arranged in the refrigerant channel 21.

[0060] The external channel 22 is a flow path for an external fluid to flow. The external fluid is a fluid that cools the refrigerant 5, such as air. The external fluid is not particularly limited. Figure 1 ) is open to the outside. The external passage 22 is not connected to the refrigerant passage 21 and the boiling section 10 (accommodation section 12). The external passage 22 is formed to penetrate the cooler 100 along the Y direction. Corrugated fins 22a extending along the Y direction are arranged in the external passage 22.

[0061] like Figure 3 As shown, the condensing section 20 includes a connecting path 24 that connects the refrigerant channel 21 with the boiling section 10. The four refrigerant channels 21 are connected to the receiving section 12 of the boiling section 10 via the connecting paths 24 extending in the Z direction. The connecting path 24 is a channel (branch path) formed in a manner that has one end connected to the connecting portion 12c of the boiling section 10 and is connected to the end opening of each refrigerant channel 21 on the side of the X direction. The connecting paths 24 (two) are respectively arranged at one end and the other end of the refrigerant channel 21 in the X direction. One connecting path 24 plays the function of supplying the gas phase refrigerant 5 vaporized in the boiling section 10 from the boiling section 10 to each refrigerant channel 21, and the other connecting path 24 plays the function of supplying the liquid phase refrigerant 5 condensed in each refrigerant channel 21 from the condensing section 20 to the boiling section 10. The connecting portion 12c of the boiling section 10 is a connecting port (opening) for allowing the refrigerant 5 to flow between the boiling section 10 and the condensing section 20. The communication portion 12c is formed in the partition plate 23a that separates the storage portion 12 from the condensation portion 20. The communication portion 12c is provided at one end portion and the other end portion of the boiling portion 10 in the X direction, corresponding to the two connection paths 24.

[0062] When the heat of the heating element HS is transferred to the boiling surface portion 13 via the mounting portion 11, the liquid phase refrigerant 5 stored in the storage portion 12 is heated and boils. The gas phase refrigerant 5 that is vaporized by boiling passes through a (at Figure 3The gas phase refrigerant 5 is cooled and condensed in the refrigerant channel 21 by heat exchange with the external fluid flowing in the adjacent external channel 22. The condensed liquid phase refrigerant 5 moves in the refrigerant channel 21 and passes through another (in the left side) communication portion 12c and the connection path 24. Figure 3 The connecting path 24 (right side in the middle) and the communicating portion 12c are returned to the housing portion 12. In this way, the refrigerant 5 sealed in the cooler 100 circulates between the boiling portion 10 and the condensing portion 20 by heat input from the heating element HS. With the circulation of the refrigerant 5, the heating element HS is cooled.

[0063] (Structure of boiling face)

[0064] Here, in the first embodiment, Figure 2 As shown, the boiling surface portion 13 has a groove portion 14 extending in a linear shape. Moreover, the groove portion 14 has an irregular concave-convex shape formed by the melting and solidification of the material due to the energy beam processing (refer to Figure 6 (B)). The groove portion 14 mainly has the following functions: (1) increasing the heat transfer area in the boiling surface portion 13 (the surface area in contact with the refrigerant 5); (2) providing a concave-convex portion that serves as the starting point of nucleate boiling of the refrigerant 5; and (3) serving as a flow path for the refrigerant 5, supplying new liquid-phase refrigerant 5 to the detachment site when bubbles generated inside the groove portion 14 detach from the groove portion 14. In addition, the groove portion 14 is a non-through groove that opens on the side of the boiling surface portion 13 and has a bottom. The groove portion 14 is a linear recessed portion whose length along the boiling surface portion 13 is greater than its depth relative to the boiling surface portion 13.

[0065] In the first embodiment, the boiling surface portion 13 is formed integrally with the surface 11 b of the mounting portion 11 . Figure 2 In the example of FIG. 1 , the boiling surface 13 is a flat surface portion formed in a manner of protruding from the surface 11b. The groove 14 is formed by subjecting the boiling surface 13 to energy beam processing. Energy beam processing refers to irradiating the boiling surface 13 with an energy beam EB in a linear pattern (refer to FIG. 1 ). Figure 7 ) is used to perform the groove processing. The irradiated energy beam EB is, for example, a laser beam (laser).

[0066] The material of the boiling surface 13 is not particularly limited, and may be aluminum, for example. Aluminum is suitable as the material of the boiling surface 13 because of its high thermal conductivity, and is suitable for reducing the weight of the cooler 100 because of its light weight. In addition, aluminum is a concept including pure aluminum and aluminum alloys.

[0067] refer to Figures 4 to 9, a structural example of the boiling surface 13 is described. In addition, in the following, two directions that are approximately orthogonal to each other in a plane parallel to the boiling surface 13 are respectively set as direction A and direction B. The direction orthogonal to the boiling surface 13 (the thickness direction of the boiling surface 13) is set as direction C. As an example, in the first embodiment, direction A is consistent with direction X, and direction B is consistent with direction Y. In the first embodiment, direction C is consistent with direction Z. In addition, direction A and direction B are examples of "first direction" and "second direction" in the claims, respectively.

[0068] (Formation range, orientation and arrangement of the groove)

[0069] Figure 4 In the example shown, the groove 14 is formed in a predetermined range in the boiling surface portion 13. The predetermined range includes the heating element HS on the mounting surface 11a (refer to Figure 3 ) overlaps at least a portion of region FP in the thickness direction of the mounting portion 11. Region FP has a projection shape obtained by projecting the area occupied by the heating element HS on the mounting surface 11a of the mounting portion 11 onto the boiling surface portion 13 in the thickness direction (Z direction) of the mounting portion 11. Figure 4 In the example, the specified range is a range that includes the area FP and is larger than the area FP.

[0070] For example, if the entire groove 14 formed in the region FP is extracted and a pattern is assumed in which the groove 14 is enclosed by an envelope, the area of ​​the pattern is 80% or more of the area of ​​the region FP. Figure 4 In the example of , the groove 14 extends from one outer peripheral edge of the region FP to the other outer peripheral edge. The groove 14 extends across the outside of the region FP and the inside of the region FP.

[0071] One or more grooves 14 are formed on the boiling surface portion 13. The grooves 14 can be formed by bending a single groove 14 so as to extend over the entire region FP as if drawn in one stroke (see FIG. Fig.14 , Fig.15 ), it is also possible to form a plurality of separate grooves 14 arranged over the entire region FP (see Figure 4 ).like Figure 4 As shown, when a plurality of grooves 14 are provided, the number of grooves 14 formed in the region FP is 10 or more, 100 or more, or 1000 or more. Figure 4 and Figure 5In order to explain the schematic pattern of the plurality of grooves 14, only a very small number of grooves 14 are schematically illustrated. In fact, the plurality of grooves 14 can be formed at a higher density than that illustrated. For example, in a plan view, the total area of ​​the grooves 14 in the region FP is 30% or more, preferably 50% or more, and more preferably 70% or more of the total area of ​​the non-groove portion (the portion where the grooves 14 are not formed) in the region FP.

[0072] The spacing between the plurality of grooves 14 is less than 1 mm, preferably less than 500 μm, and more preferably less than 200 μm. This is because, as the spacing is smaller, more grooves 14 can be configured, which can increase the heat transfer area (surface area) of the boiling surface 13 accordingly. Fig.14 and Fig.15 ), the above-mentioned pitch can also be applied to the interval between adjacent line segments LS in a single groove portion 14.

[0073] The maximum opening width of the groove portion 14 (i.e., the maximum value of the groove width when viewed from above) is less than 1 mm, preferably less than 500 μm, and more preferably less than 200 μm. This is because the groove width suitable for becoming the starting point of nucleate boiling of the refrigerant 5 in the liquid phase is in the range of several μm to several hundred μm. The maximum opening width of the groove portion 14 is greater than 1 μm, for example, greater than 10 μm. This is because if the groove width is less than 1 μm, the groove width is too small to function as the starting point of nucleate boiling of the refrigerant 5. Preferably, the groove portion 14 has a maximum opening width of greater than 1 μm and less than 1 mm.

[0074] (First example of groove)

[0075] Figure 4 In the first example of the grooves 14 shown, a plurality of grooves 14 are formed on the boiling surface portion 13. Each of the plurality of grooves 14 extends linearly.

[0076] Figure 4 In the embodiment, the plurality of grooves 14 include a plurality of first grooves 14a and a plurality of second grooves 14b. The plurality of first grooves 14a extend in a first direction (direction A) along the boiling surface portion 13. The plurality of second grooves 14b extend in a second direction (direction B) different from the first direction (direction A) along the boiling surface portion 13, and intersect with the plurality of first grooves 14a. Figure 4 In the embodiment, the plurality of first grooves 14a extend in the A direction and are arranged along the B direction. The plurality of second grooves 14b extend in the B direction and are arranged along the A direction. The first direction (the A direction) and the second direction (the B direction) are orthogonal to each other.

[0077] In the first embodiment, the first direction (direction A) is a direction from the boiling surface portion 13 toward the communicating portion 12c in the boiling portion 10. As described above, in the first embodiment, the direction A coincides with the direction X. Figure 5 As shown, in the X direction, a boiling surface portion 13 is arranged substantially in the center of the boiling portion 10, and a connecting portion 12c is provided at both ends of the boiling portion 10 in the X direction (refer to Figure 3 ). Therefore, the direction from the boiling surface portion 13 toward the connecting portion 12c side is the X direction (A direction). In other words, the plurality of first groove portions 14a extend along the flow direction of the liquid phase refrigerant 5 moving from the connecting portion 12c toward the boiling surface portion 13. Moreover, the number of the first groove portions 14a is greater than the number of the second groove portions 14b. Therefore, the plurality of first groove portions 14a function as a main path for the refrigerant 5 to flow in the X direction (A direction) along the flow direction of the refrigerant 5 in the boiling portion 10, and the plurality of second groove portions 14b function as a secondary path for the refrigerant 5 to flow into the first groove portions 14a from the side.

[0078] Figure 4 In the boiling surface portion 13, a plurality of first groove portions 14a are arranged at a constant pitch Pt1, and a plurality of second groove portions 14b are arranged at a constant pitch Pt2. Moreover, the pitch Pt2 is set to be larger than the pitch Pt1. In the boiling surface portion 13, the portion between these plurality of groove portions 14 (the first groove portion 14a, the second groove portion 14b) is a flat surface without groove processing.

[0079] Figure 6 The cross-sectional shape of the groove portion 14 according to the first example is shown. Figure 6 (A) is a schematic conceptual diagram (processing image) of energy beam processing of the boiling surface 13. Figure 6 (B) is a schematic diagram of the cross-sectional shape of the groove portion 14 formed in the boiling surface portion 13 as a result of the energy beam processing according to the first embodiment.

[0080] like Figure 6 As shown in FIG. 2A , the boiling surface 13 is linearly irradiated (scanned) with an energy beam EB (reference Figure 7 ), the boiling surface 13 is subjected to linear groove processing. Figure 7 As shown, if the energy beam EB irradiates the initial surface IS (the surface before the groove portion 14 is formed) of the boiling surface portion 13, the material (parent material) constituting the boiling surface portion 13 absorbs the energy of the energy beam EB, thereby generating rapid heat in the material. As a result, the material whose temperature rises to the melting point melts and / or evaporates, and splashes from the irradiation portion of the energy beam EB, and as a result, the material is removed from the initial surface IS. Figure 7The double-dashed arrows indicate the expansion, splashing or accumulation of the material. As a result, a groove-shaped recessed portion is formed on the boiling surface portion 13, and a part of the splashed material is cooled and accumulated near the recessed portion. In addition, the material melted / evaporated by the irradiation of the energy beam EB splashes with rapid expansion, so that irregular and minute concave-convex shapes are formed on the inner surface of the recessed portion.

[0081] As a result, the groove 14 formed on the boiling surface 13 after the energy beam processing is Figure 6 The groove pattern shown in (A) is the base tone, such as Figure 6 (B) has an irregular concave-convex shape. Figure 6 As shown in (B), the grooves 14 formed in the boiling surface portion 13 each have an irregular concavo-convex shape formed as the material is melted and solidified by energy beam processing.

[0082] In addition, in conventional energy beam processing (for example, laser precision processing), the irregular concave-convex shape as described above is regarded as a shape indicating low processing accuracy, and the irradiation conditions of the energy beam EB (energy density or irradiation time (pulse width) etc.) are optimized so as to avoid the generation of concave-convex shapes as much as possible. As a result, a processed surface that is as uniform as possible and has few concave-convex shapes is formed in conventional energy beam processing. In contrast, the groove portion 14 of the first embodiment is intended to actively form concave-convex shapes on the processed surface, and adopts irradiation conditions different from the irradiation conditions of the energy beam EB optimized in conventional energy beam processing, thereby forming an irregular concave-convex shape. In particular, the energy beam EB is irradiated with an energy density that is generally considered excessive, thereby forming the following. Figure 6 (B) shows an irregular groove portion 14 with a concave-convex shape. Furthermore, if an energy beam EB with particularly high energy and short pulse is irradiated, the material will undergo ablation. Ablation refers to a phenomenon in which the surface of a material is instantly decomposed and explosively evaporated by applying high energy to the irradiated part in a very short time. By causing ablation, it is possible to effectively form concave-convex shapes on the surface of the processed part. In the formation of the groove portion 14, energy beam processing accompanied by such ablation can be performed.

[0083] Figure 6 In the example shown in (B), the groove portion 14 includes space portions 15a to 15d, and the space portions 15a to 15d are composed of at least any one of a hole portion opening in the boiling surface portion 13, a hollow portion in which at least a portion of the opening portion in the hole portion is covered, a horizontal hole portion extending laterally from the hole portion or the hollow portion, and a tunnel-shaped portion in which a portion of the opening of the groove portion 14 is covered.

[0084] The space portion 15a formed by the hole portion opening in the boiling surface portion 13 refers to a local hole (recess) surrounded by the entire circumference of the inner surface of the groove portion 14 and the portion with the upper end open (opening). The space portion 15b formed by the hollow portion is a portion where a part or all of the opening portion of the hole formed by the energy beam EB is covered due to the stacking of materials splashed by the irradiation of the energy beam EB. The space portion 15b refers to a hollow space where the opening portion is smaller than the maximum width of the internal space or where no opening portion is formed. The space portion 15c formed by the horizontal hole portion refers to a space portion formed in a manner of being recessed in a side direction different from the depth direction of the groove portion 14 (i.e., the irradiation direction of the energy beam EB) due to the rapid expansion of the material accompanying the irradiation of the energy beam EB. In addition, sometimes a shape in which the opening portion is covered due to the stacking of splashed materials, such as the space portion 15b, is formed in the opening portion of the groove portion 14. In this case, the groove portion 14 includes a space portion 15d formed by a tunnel-shaped portion in which a part of the opening along the extension direction of the groove portion 14 is covered. The “irregular” concavo-convex shape formed by irradiation with the energy beam EB includes at least any one of such space portions 15 a to 15 d .

[0085] Such space portions 15a to 15d are structures formed locally in a part of the groove portion 14. That is, the space portions 15a to 15d are parts of the groove portion 14 (constituent elements of the irregular concavo-convex shape), and are partial structures smaller than the groove portion 14 which is the main structure. Such local concavo-convex is suitable as the starting point of nucleate boiling of the refrigerant 5.

[0086] (Second example of groove)

[0087] Figure 8 , a second example of the groove 14 is shown. In the second example, at least a portion of the groove 14 has a bottom 16a having a width wider than the opening width W1 of the groove 14 in a cross section perpendicular to the extending direction of the groove 14. That is, the groove 14 is formed so that the width W2 of the bottom 16a of the groove 14 is larger than the opening width W1 of the groove 14 on the main surface of the boiling surface portion 13. In addition, Figure 8 and Figure 6 (A) is a schematic conceptual diagram (processing image) of energy beam processing in the same manner, but the irregular concavo-convex shape of the groove portion 14 is not shown.

[0088] The groove portion 14 having the bottom 16a with a wide width is formed, for example, by irradiating the same portion of the boiling surface portion 13 with energy beams EB whose optical axes AX are tilted in different directions. That is, the groove portion 14 is formed by irradiating (scanning) the same portion of the boiling surface portion 13 with a multi-pass energy beam EB, and the optical axis AX of the energy beam EB in each path is tilted from the normal direction relative to the main surface of the boiling surface portion 13.

[0089] Figure 8 In (A), in a cross section orthogonal to the extending direction of the groove 14, a groove 14 is formed by irradiating the same part of the boiling surface 13 with a first energy beam EB that tilts the optical axis AX to one side and a second energy beam EB that tilts the optical axis AX to the other side. The trajectories (dashed line portions) of the energy beams EB pass through overlapping positions on the main surface of the boiling surface 13, thereby forming an opening 16b with a relatively narrow width in the groove 14. The trajectories of the energy beams EB are inclined in a direction that separates from each other as they move from the main surface toward the depth direction, thereby forming a bottom 16a that extends further outward than the opening 16b.

[0090] Figure 8 In (B), in a cross section orthogonal to the extension direction of the groove portion 14, the same portion of the boiling surface portion 13 is irradiated with a first energy beam EB tilted to one side, a second energy beam EB tilted to the other side, and a third energy beam EB not tilted but along the normal direction. The material of the portion directly below the intersection (opening 16b) of the trajectory of the first energy beam EB and the trajectory of the second energy beam EB is removed by the third energy beam EB. As a result, a groove portion 14 having a cross-sectional shape that expands downward in a fan shape relative to the opening 16b is formed.

[0091] (Third example of groove)

[0092] Fig. 9 3 shows a third example of the groove portion 14. In the third example, the boiling surface portion 13 includes a plurality of first regions 17a in which the groove portion 14 is formed and a second region 17b disposed between the plurality of first regions 17a and in which the groove portion 14 is not formed. Both the first region 17a and the second region 17b are provided at least in a region FP (refer to Figure 4 ) and can extend to the outside of region FP.

[0093] The grooves 14 are formed, for example, over substantially the entire first region 17a. For example, a plurality of grooves 14 (first grooves 14a and second grooves 14b) are formed at a predetermined pitch in the first region 17a. The second region 17b is a flat surface where no grooves 14 are formed.

[0094] Fig. 9 (A) and Fig. 9 In (B), the first region 17a and the second region 17b extend linearly in the boiling surface portion 13. In the boiling surface portion 13, a plurality of first regions 17a and a plurality of second regions 17b are arranged alternately.

[0095] and, Fig. 9 (A) and Fig. 9In (B), the main surface of the boiling surface portion 13 is formed as a flat surface, and the first region 17a and the second region 17b are formed on the flat main surface.

[0096] Fig. 9 (C) and Fig. 9 In (D), each of the plurality of first regions 17a is formed in a step shape offset in the thickness direction (C direction) of the boiling surface portion 13 relative to the adjacent second region 17b. Fig. 9 (C) and Fig. 9 In the example of (D), a groove-shaped structure 17 is formed on the main surface of the boiling surface portion 13, with the first region 17a being the top surface of the convex portion and the second region 17b being the bottom surface of the concave portion. The first region 17a is formed as a step difference that is offset in a manner protruding in the thickness direction relative to the adjacent second region 17b. Furthermore, the groove portion 14 (the first groove portion 14a and the second groove portion 14b) is formed on the first region 17a constituting the top surface of the convex portion. In this way, Fig. 9 (C) and Fig. 9 In the example (D), a relatively large (macroscopic) groove structure 17 composed of a first region 17a and a second region 17b and a relatively small (microscopic) groove portion 14 formed in the first region 17a as a part of the groove structure 17 are formed on the boiling surface portion 13. The groove width W3 in the groove structure 17 (i.e., the width of the second region 17b) is larger than the opening width W1 of the groove portion 14 (refer to Figure 6 (A)). The opening width W1 of the groove portion 14 is less than 1 mm, whereas the groove width W3 of the groove-like structure 17 is greater than 1 mm, for example, greater than 2 mm and less than 5 mm. Fig. 9 (C) and Fig. 9 In (D), the width of the first region 17a is also equal to the groove width W3 (that is, the width of the second region 17b).

[0097] (Function of the groove)

[0098] refer to Fig.10 , the function of forming the groove portion 14 on the boiling surface portion 13 is described.

[0099] To simplify the nucleate boiling on the heat transfer surface (boiling surface 13), it is a phenomenon in which the stages of evaporation of the refrigerant 5 on the heat transfer surface, formation of bubbles, detachment of the bubbles from the heat transfer surface, and supply of the liquid phase refrigerant 5 to the heat transfer surface are repeated. Even if the heat transfer surface is flat, tiny scratches or holes can become the starting point (bubble point) of bubbles.

[0100] Fig.10 (A) to (C) are schematic diagrams showing boiling models according to a comparative example in which a circular hole 90 is formed on a heat transfer surface. Fig.10 (A) is a top view of the circular hole 90, Fig.10 (B) is a PP cross-sectional view of the circular hole 90, Fig.10 (C) is a QQ cross-sectional view of the circular hole 90. The circular hole 90 has substantially the same cross-sectional shape in the PP cross section and the QQ cross section, and the internal space of the circular hole 90 is surrounded by the inner peripheral wall 91 over the entire circumference.

[0101] In the circular hole 90 of the comparative example, the liquid-phase refrigerant 5 can flow in only from a portion of the opening 92. In other words, the detachment of the bubbles BG from the circular hole 90 and the supply of the liquid-phase refrigerant 5 to the circular hole 90 are both performed only through the same opening 92. Therefore, in the comparative example, at the stage where the heat input is small and small bubbles BG are sparsely formed (refer to the dotted line portion), the detachment of the bubbles BG and the supply of the liquid-phase refrigerant 5 can be performed in a well-balanced manner. On the other hand, if the heat input becomes larger and the formation and detachment of the bubbles BG in the circular hole 90 become intense, the bubbles BG will hinder the supply of the liquid-phase refrigerant 5 from the opening 92. As a result, the large bubbles BG (refer to the solid line portion) in the circular hole 90 fill up to the opening 92, and the inside of the circular hole 90 becomes a dry state (a state of film boiling). Even if the inner peripheral wall 91 and the bottom 93 are roughened by energy beam processing, the situation that hinders the supply of the liquid-phase refrigerant 5 into the circular hole 90 cannot be improved.

[0102] Fig.10 (D) to (F) are schematic diagrams showing a boiling model of one groove portion 14 formed in the boiling surface portion 13 according to the first embodiment. Fig.10 (D) is a schematic top view of the groove portion 14, Fig.10 (E) is a PP cross-sectional view of the groove portion 14, Fig.10 (F) is a QQ cross-sectional view of the groove portion 14. The groove portion 14 is aligned with the circular hole 90 ( Fig.10 (B)) is similarly surrounded by the inner wall 16c, but is not surrounded by the inner wall 16c in the QQ cross section (the groove 14 extends along the QQ cross section).

[0103] In the groove portion 14 according to the first embodiment, the liquid refrigerant 5 can flow in from the opening portion 16b in the vertical direction. Fig.10 As shown in (F), the liquid-phase refrigerant 5 in the groove 14 can flow in the direction along the QQ line (the direction in which the groove 14 extends). The bubbles BG generated in the groove 14 are separated from the groove 14 via the opening 16b just above the groove 14, while the liquid-phase refrigerant 5 can flow in the direction along the groove 14 and be supplied to the separation site of the bubbles BG. That is, in the case of the groove 14, the separation path of the bubbles BG and the supply path of the liquid-phase refrigerant 5 can be made different.

[0104] In the PP cross section, the groove 14 is a narrow space surrounded by a heat transfer surface (inner wall 16c) as in the comparative example, so that heat conduction is efficiently performed to the liquid phase refrigerant 5 in the space. In addition, there are multiple locations that become the starting point of nucleate boiling in the irregular concave-convex groove 14, so even under the condition of small heat input, the generation rate of bubbles BG (see the dotted line portion) can be increased compared with a flat heat transfer surface. If the heat input becomes larger and the formation and separation of bubbles BG become intense, the groove 14 in the PP cross section may be filled with bubbles BG (see the solid line portion). However, in this case, there is no inner wall 16c in the QQ cross section and the liquid phase refrigerant 5 can flow, so the supply of the liquid phase refrigerant 5 accompanied by the separation of bubbles BG can be smoothly performed. As a result, in the groove 14 of the first embodiment, local drying up inside the groove 14 can be suppressed compared with the comparative example.

[0105] Furthermore, in the first embodiment, the first groove portion 14a and the second groove portion 14b intersect (see Figure 4 ), so at the intersection of the first groove portion 14a and the second groove portion 14b, there is no inner wall 16c in the PP section and the QQ section. Therefore, it can be said that the generation rate of bubbles BG at the intersection is relatively low compared to other parts in the groove portion 14, and it is not easy to become a dry state (liquid phase refrigerant 5 is easy to exist). By locally providing a part in the groove portion 14 where the liquid phase refrigerant 5 is more likely to exist than other parts, it is easy to continue to supply the liquid phase refrigerant 5 to the groove portion 14 even when the heat input increases and bubbles BG are generated violently in most of the groove portion 14. That is, providing the intersecting groove portion 14 helps to increase the limit level of the heat input amount until dryness occurs.

[0106] (Method for manufacturing a boiling cooler)

[0107] refer to Figures 11 to 13 , a manufacturing method of the cooler 100 involved in the first embodiment is described. The manufacturing method of the cooler 100 is a manufacturing method of a boiling type cooler having a boiling section 10 for boiling the refrigerant 5 by heat exchange with a heating element HS and a condensing section 20 for condensing the refrigerant 5 vaporized in the boiling section 10 and returning it to the boiling section 10.

[0108] like Fig.11 As shown, the manufacturing method of the cooler 100 includes a process of forming the condensation portion 20. The process of forming the condensation portion 20 includes a process of forming the condensation portion 20 by joining the refrigerant channel forming portion 21b to become the refrigerant channel 21 and the external channel forming portion 22b to become the external channel 22. The joining can be performed by welding or brazing, for example.

[0109] like Fig.12As shown, the method for manufacturing the cooler 100 includes a step of forming the boiling portion 10 .

[0110] Here, in the first embodiment, Figure 6 and Figure 7 As shown in FIG. 1 , the process of forming the boiling portion 10 includes the process of forming the groove portion 14 on the boiling surface portion 13. That is, in the process of forming the groove portion 14 on the boiling surface portion 13, the boiling surface portion 13 is irradiated with the energy beam EB in a linear pattern to perform groove processing. Then, by this groove processing, the groove portion 14 having an irregular concave-convex shape formed by the melting and solidification of the material due to the energy beam processing is formed on the boiling surface portion 13 (refer to FIG. 1 ). Figure 6 ).

[0111] In the first embodiment, the boiling surface 13 is irradiated with light in the A direction (reference Figure 4 ) to form a plurality of first grooves 14a. Then, the boiling surface 13 is directed at a predetermined interval (pitch Pt2) in parallel with each other and in the B direction (reference Figure 4 ) in a linear pattern to form a plurality of second grooves 14b. The irradiation of the energy beam EB may be continuous irradiation or pulse irradiation (intermittent irradiation). As described above, various parameters related to the irradiation of the energy beam EB are set to values ​​suitable for forming grooves 14 having irregular concave-convex shapes. For example, when the energy beam EB is a laser beam, the set parameters include laser output power, energy density, laser wavelength, etc. The beam diameter (spot diameter) and focal position of the energy beam EB can be determined according to the opening width W1 (reference Figure 6 ) to set.

[0112] When forming one groove portion 14, the energy beam EB may be irradiated multiple times (multi-path). Figure 8 ), multiple beam irradiation (scanning) is performed with the angle of the optical axis AX set to different values. In addition, in the case of the third example, in the boiling surface 13, the energy beam processing (groove processing) is selectively performed on the first area 17a set in advance, and the second area 17b is excluded from the energy beam processing (groove processing) object. In addition, in the third example, when the angle of the optical axis AX is set to different values, the energy beam processing (groove processing) is selectively performed on the first area 17a set in advance, and the second area 17b is excluded from the energy beam processing (groove processing) object. Fig. 9 In the case of the groove-like structures 17 shown in (C) and (D), the second regions 17b are formed by removing the portion between the first regions 17a from the main surface of the boiling surface portion 13 by cutting, for example, to form a step.

[0113] Furthermore, when the first region 17a and the second region 17b are parallel straight lines, extrusion molding is used as a method of providing the groove-like structure 17. That is, the mounting portion 11 forming the boiling surface portion 13 can be extruded along the A direction to form the groove-like structure 17 on the boiling surface portion 13. Alternatively, the boiling surface portion 13 can be formed on one side of an extruded profile that is separately provided from the mounting portion 11, and the other side of the extruded profile can be joined to the surface 11b of the mounting portion 11.

[0114] In the first embodiment, if Fig.12 As shown, the process of forming the boiling portion 10 includes the process of joining the mounting portion 11 provided with the boiling surface portion 13 to the receiving portion 12. For example, the direction (A direction) of the first groove portion 14a is consistent with the X direction (reference Figure 5 ) in a manner to align the orientation of the mounting portion 11, and in a state where the mounting portion 11 is arranged at a position covering the hole portion 12d of the receiving portion 12 (in this case, the boiling surface portion 13 is arranged in the hole portion 12d), the four sides (the entire circumference) of the contact portion between the mounting portion 11 and the receiving portion 12 are welded to the receiving portion 12.

[0115] like Fig.13 As shown, the manufacturing method of the cooler 100 also includes a step of joining the boiling section 10 to the condensing section 20. For example, by welding, the peripheral edge of the upper end surface of the receiving section 12 (the outer peripheral portion of the end surface of the peripheral wall 12b) is joined to the lower surface of the condensing section 20. Thus, the cooler 100 is completed. Then, the heating element HS is installed on the installation surface 11a of the installation section 11.

[0116] (Effects of the First Embodiment)

[0117] In the first embodiment, the following effects can be obtained.

[0118] In the first embodiment, as described above, the boiling surface portion 13 includes the groove portion 14 extending linearly and having an irregular concave-convex shape formed as the material is melted and solidified by the energy beam processing (see Figure 6 ), therefore, the irregular concavo-convex groove 14 formed on the boiling surface 13 becomes the starting point of nucleate boiling, which can increase the generation rate of bubbles BG. Moreover, the concavo-convex shape is not a hole surrounded by the periphery, but a groove 14 extending in a linear shape, so that at least no barrier is formed in the extending direction of the groove 14, and the liquid phase refrigerant 5 can flow. That is, since a pair of inner side surfaces (inner wall 16c, refer to Fig.10), therefore, by greatly ensuring the heat transfer area to the liquid-phase refrigerant 5, the generation rate of the bubbles BG can be increased, and since no inner side surface (inner wall 16c) is formed in the extending direction of the groove portion 14, the generated bubbles BG are separated from the groove portion 14, and the liquid-phase refrigerant 5 can be smoothly supplied from the outside of the groove portion 14 to the inside of the groove portion 14. As a result, by forming the concavoconvex on the boiling surface portion 13, the generation rate of the bubbles BG can be increased, and the occurrence of local drying can be suppressed.

[0119] First embodiment (reference Figure 6 ), as described above, the groove portion 14 includes space portions 15a to 15d formed by at least any one of a hole portion opening in the boiling surface portion 13, a hollow portion in which at least a part of the opening portion in the hole portion is covered, a horizontal hole portion extending laterally from the hole portion or the hollow portion, and a tunnel-shaped portion in which a part of the opening of the groove portion 14 is covered, so that a portion that becomes the starting point of nucleate boiling can be effectively formed on the boiling surface portion 13. As a result, the generation rate of the bubbles BG in the boiling surface portion 13 can be effectively increased.

[0120] First embodiment (reference Figure 6 ) as described above, the space portions 15a to 15d are structures locally formed in a portion of the groove portion 14, and therefore, fine space portions 15a to 15d suitable for generating bubbles BG can be provided in the groove portion 14 as a partial structure of the groove portion 14.

[0121] Second Example of the First Embodiment (reference Figure 8 ), as described above, at least a portion of the groove 14 has a bottom 16a having a width wider than the opening width W1 of the groove 14 in a cross section perpendicular to the extending direction of the groove 14, so that the width of the internal space of the groove 14 is greater than the opening width W1, and an internal space of a shape that surrounds the bubbles BG generated at the bottom 16a of the groove 14 from both sides to the opening 16b is formed. Thus, the inner surface area (heat transfer area) of the groove 14 can be increased. As a result, heat can be efficiently transferred to the refrigerant 5 in the groove 14.

[0122] First embodiment (reference Figure 4 ), as described above, the plurality of grooves 14 include a plurality of first grooves 14a extending in the first direction (direction A) along the boiling surface portion 13 and a plurality of second grooves 14b extending in the second direction (direction B) different from the first direction (direction A) along the boiling surface portion 13 and intersecting the plurality of first grooves 14a, so that, for example, compared with a structure in which the linear grooves are simply arranged in parallel, the liquid-phase refrigerant 5 can be more efficiently supplied in the extending direction of the grooves 14. As a result, local drying up in the grooves 14 can be further effectively suppressed.

[0123] First embodiment (reference Figure 5 ), as described above, the first direction (direction A) is the direction from the boiling surface portion 13 toward the connecting portion 12c side in the boiling portion 10, so that the flow direction of the refrigerant 5 when the refrigerant 5 circulates between the boiling portion 10 and the condensing portion 20 can be consistent with the first direction (direction A) extending from the first groove portions 14a having a large number. That is, the liquid-phase refrigerant 5 returning from the condensing portion 20 to the boiling portion 10 flows into the boiling portion 10 from the connecting portion 12c, and moves to the position of the boiling surface portion 13 in the boiling portion 10, so that the flow of the liquid-phase refrigerant 5 is formed in a direction substantially the same as the first direction (direction A). Moreover, the number of the first groove portions 14a is greater than the number of the second groove portions 14b, so that the liquid-phase refrigerant 5 can be more effectively supplied to the first groove portion 14a along the flow direction of the liquid-phase refrigerant 5. As a result, local drying up in the groove portion 14 can be further and more effectively suppressed.

[0124] The third example of the first embodiment (reference Fig. 9 ), as described above, the boiling surface portion 13 includes a plurality of first regions 17a in which the grooves 14 are formed and second regions 17b disposed between the plurality of first regions 17a and in which the grooves 14 are not formed. Therefore, the first regions 17a in which the efficiency of generating the bubbles BG is relatively high can be provided on the boiling surface portion 13, and the second regions 17b in which the efficiency of generating the bubbles BG is relatively low and in which a large amount of liquid-phase refrigerant 5 is present can be provided between the first regions 17a. Thus, for example, even in a situation where the heat flux is large and drying is likely to occur in the grooves 14 formed in the first regions 17a, the effect of supplying the liquid-phase refrigerant 5 from the second regions 17b to the first regions 17a can be obtained. As a result, drying in the grooves 14 can be suppressed.

[0125] Moreover, in Example 3 Fig. 9 In the examples shown in (C) and (D), as described above, each of the plurality of first regions 17a is formed in a stepped shape offset in the thickness direction of the boiling surface portion 13 relative to the adjacent second region 17b, so that a relatively large groove-shaped first structure (groove-shaped structure 17) is formed on the boiling surface portion 13 by the adjacent first region 17a and second region 17b, and a relatively small groove-shaped second groove-shaped structure is formed on the surface of the first region 17a in the groove-shaped structure 17 by the groove portion 14. Thus, compared with the case where only the groove portion 14 is provided on the flat boiling surface portion 13, the heat transfer area of ​​the boiling surface portion 13 (the surface area in contact with the liquid-phase refrigerant 5) can be increased.

[0126] In the first embodiment, as described above, the groove 14 has a maximum opening width of 1 μm or more and less than 1 mm, so that the groove 14 can be provided with a size suitable for the start point of nucleate boiling in the liquid refrigerant 5. As a result, the generation rate of bubbles BG in the boiling surface 13 can be effectively increased.

[0127] (First Modification of the Formation Pattern of the Groove Portion)

[0128] Fig.14 express Figure 4 A first modified example of the formation pattern of the groove portion 14 is shown. Fig.14 In the example of FIG. 1 , only one groove 14 is provided on the boiling surface 13. The groove 14 extends in the direction A, bends in the direction B at the end of the direction A of the formation range of the groove 14, and then extends in the reverse direction A. By repeating this bending multiple times, the groove 14 is formed into a curved shape (meander shape) throughout a predetermined range, and the predetermined range includes the heating element HS (reference Figure 3 )'s setting area overlaps the area FP. Fig.14 FIG. 1 shows that adjacent line segments LS in a single groove portion 14 are aligned with each other. Figure 4 Example of the same constant pitch Pt1 configuration.

[0129] (Second Modification of the Formation Pattern of the Groove Portion)

[0130] Fig.15 A second modified example of the formation pattern of the groove portion 14 is shown. Fig.15 In the example of FIG. 1 , only one groove 14 is provided on the boiling surface 13. The groove 14 is formed by a spiral pattern. The groove 14 is formed by a radius from the heating element HS (reference Figure 3 The central part of the area FP overlapping the setting area of ​​the heating element HS (reference) is formed in a spiral shape in a manner that expands toward the outer peripheral side. Each line segment LS constituting the spiral shape is a straight line. The groove portion 14 is formed in a spiral shape throughout the entire predetermined range, and the predetermined range includes the heating element HS (reference Figure 3 )'s setting area overlaps the area FP. Fig.15 FIG. 1 shows that adjacent line segments LS in a single groove portion 14 are aligned with each other. Figure 4 Example of the same constant pitch Pt1 configuration.

[0131] (Another example of the formation pattern of the groove portion)

[0132] The formation pattern of the groove portion 14 is not limited to Figure 4 , Fig.14 and Fig.15For example, the groove 14 may be formed by an annular pattern. For example, a plurality of annular grooves 14 may be formed in a concentric shape (e.g., concentric circles or concentric rectangles). The groove 14 is not limited to a straight line, and may also extend in a curved line.

[0133] (First Modification of First Embodiment)

[0134] refer to Fig.16 , a first modification of the first embodiment described above will be described. In this first modification, unlike the first embodiment described above in which the mounting portion 11 is joined to the receiving portion 12 by welding, the mounting portion 11 and the receiving portion 12 (see Figure 3 ) is illustrated by an example of integral formation.

[0135] Fig.16 In the example shown, a recess 11c is provided on the mounting portion 11. The internal space of the recess 11c is utilized as the first embodiment (see Fig.12 ) of the internal space of the receiving portion 12. Therefore, Fig.16 In the embodiment, the receiving portion 12 is not provided as a separate component. The inner bottom surface of the recess 11c constitutes the surface 11b, and the boiling surface portion 13 is formed on the surface 11b.

[0136] Fig.16 In the example shown, the process of joining the boiling section 10 and the condensing section 20 includes the process of joining the mounting section 11 to the condensing section 20 by brazing. At this time, a brazing sheet 30 having a core material and brazing materials provided on both sides of the core material is provided between the condensing section 20 and the mounting section 11. The mounting section 11 is brazed to the condensing section 20 via the brazing sheet 30. Thus, the boiling section 10 and the condensing section 20 are joined, and the cooler 100 is completed. In addition, the heating element HS is installed on the mounting surface 11a of the mounting section 11.

[0137] In addition, after the groove portion 14 is formed on the boiling surface portion 13, an assembly in which the parts constituting the boiling portion 10 and the parts constituting the condensing portion 20 are assembled via a brazing material may be prepared, and the entire assembly may be brazed. In this case, the process of forming the condensing portion 20, the process of forming the boiling portion 10, and the process of joining the boiling portion 10 to the condensing portion 20 may be performed together through a single brazing process.

[0138] (Second Modification of First Embodiment)

[0139] refer to Fig.17 A second modification of the first embodiment will be described. In this second modification, unlike the first embodiment in which the mounting portion 11 is joined to the housing portion 12 by welding, an example in which the mounting portion 11 is joined to the housing portion 12 by screwing will be described.

[0140] like Fig.17 As shown, the process of forming the boiling section 10 includes the process of joining the mounting portion 11 to the accommodating portion 12 by screwing. At this time, a through hole for the screw 40 is provided in the mounting portion 11, and a threaded hole for the screw 40 is provided in the accommodating portion 12. In addition, a sealing component 50 such as an O-ring is provided between the accommodating portion 12 and the mounting portion 11. With the sealing component 50 sandwiched therebetween, the mounting portion 11 is screwed to the accommodating portion 12 by means of the screw 40. Thus, the accommodating portion 12 is formed and the boiling section 10 is formed. In this example, the accommodating portion 12 can be pre-joined to the condensing portion 20. In addition, in the case of screwing, the refrigerant 5 can also be sealed in the accommodating portion 12 by means of the sealing component 50. In addition, the heating element HS is mounted on the mounting surface 11a of the mounting portion 11.

[0141] [Second embodiment]

[0142] Next, refer to Figures 18 to 20 , the structure of a boiling type cooler 200 (hereinafter referred to as cooler 200) involved in a second embodiment of the present invention is described. In the second embodiment, unlike the first embodiment in which the boiling section 10 and the condensing section 20 are integrated, an example in which the boiling section 210 and the condensing section 220 are separated is described. In addition, for the same structure as the first embodiment, the same reference numerals are used and the description is omitted.

[0143] like Figures 18 to 20 As shown, the cooler 200 includes a boiling section 210, a condensing section 220, and a connecting section 260. The boiling section 210 boils the refrigerant 5 by heat exchange with the heating element HS. The condensing section 220 condenses the refrigerant 5 that has boiled through the boiling section 210 and returns it to the boiling section 210. The connecting section 260 is a connecting pipe that connects and communicates the boiling section 210 and the condensing section 220. The cooler 200 of the second embodiment is a separated type in which the boiling section 210 and the condensing section 220 are arranged separately from each other and communicate with each other via the connecting section 260. In addition, the second embodiment ( Figure 18 to Figure 20 ) in the figure, the illustration of the refrigerant 5 is omitted.

[0144] The boiling section 210 includes a mounting portion 11 and a receiving portion 212 (see Fig. 20 The storage portion 212 stores the liquid refrigerant 5. The recess 214a (refer to Fig. 20 ) and the surface 11b of the mounting portion 11 divide the housing portion 212. The housing portion 212 is provided as a box-shaped space. In the housing portion 212, the boiling surface portion 13 is in contact with the liquid phase refrigerant 5. In addition, the boiling surface portion 13 is the same as the first embodiment described above, and therefore will not be described in detail, and a groove portion 14 is formed on the boiling surface portion 13 by energy beam processing.

[0145] The condensation section 220 is composed of a plate-fin heat exchanger. The condensation section 220 includes a refrigerant channel 221 and an external channel 222. The refrigerant channel 221 and the external channel 222 are alternately arranged with a partition in between. The refrigerant channel 221 is a flow path for the refrigerant 5 to circulate. The refrigerant channel 221 is connected to the receiving section 212 of the boiling section 210 via the connecting section 260. Corrugated fins (not shown) extending in the X direction are arranged in the refrigerant channel 221. The external channel 222 is a flow path for the external fluid to circulate. The external channel 222 opens to the outside. The corrugated fins 222a extending in the Y direction are arranged in the external channel 222.

[0146] When the heat of the heating element HS is transferred to the boiling surface portion 13 via the mounting portion 11, the liquid phase refrigerant 5 in the housing portion 212 is heated and boils. The refrigerant 5 vaporized by boiling moves to the refrigerant channel 221 connected to the housing portion 212 via the connecting portion 260, and is cooled and condensed by the external fluid flowing in the external channel 222. The refrigerant 5 liquefied by condensation moves in the refrigerant channel 221 and the connecting portion 260 and returns to the housing portion 212. In this way, the refrigerant 5 sealed in the cooler 200 circulates between the boiling portion 210 and the condensing portion 220. As a result, the heating element HS is cooled.

[0147] (Method for manufacturing a boiling cooler)

[0148] refer to Figure 21 to Figure 23 , a method for manufacturing the cooler 200 according to the second embodiment will be described.

[0149] like Fig.21 As shown, the manufacturing method of the cooler 200 includes a process of forming a boiling portion 210. The process of forming the boiling portion 210 includes a process of forming a boiling surface portion 13 and a process of joining the mounting portion 11 to the main body 214. The process of forming the boiling surface portion 13 is the same as the first embodiment described above, and therefore will not be described in detail. The process includes a process of forming a groove portion 14 having an irregular concave-convex shape on the boiling surface portion 13 by irradiating the boiling surface portion 13 with an energy beam EB in a linear pattern to perform groove processing.

[0150] The process of joining the mounting portion 11 to the main body 214 includes joining the mounting portion 11 to the main body 214 by welding. At this time, for example, four sides (the entire circumference) of the contact portion between the mounting portion 11 and the main body 214 are welded. And, by joining the mounting portion 11 to the main body 214 by welding, the receiving portion 212 is formed. Thus, the boiling portion 210 is formed. Fig. 22As shown, the manufacturing method of the cooler 200 includes a process of forming the condensation section 220. The process of forming the condensation section 220 includes a process of forming the condensation section 220 by joining the refrigerant channel forming part 221b, which will become the refrigerant channel 221, and the external channel forming part 222b, which will become the external channel 222. And, the manufacturing method of the cooler 200 includes a process of joining the boiling section 210 and the condensation section 220 via the connecting part 260. Thereafter, the cooler 200 is completed. And, as Fig.23 As shown, the heat generating element HS is mounted on the mounting surface 11 a of the mounting portion 11 .

[0151] The other structures of the second embodiment are the same as those of the above-mentioned first embodiment.

[0152] (Effects of the Second Embodiment)

[0153] In the boiling cooler 200 and the manufacturing method of the boiling cooler 200 involved in the second embodiment, groove processing is performed by irradiating the boiling surface 13 with an energy beam EB in a linear pattern to form a groove portion 14 having an irregular concave-convex shape formed by the melting and solidification of the material caused by the energy beam processing on the boiling surface 13. Therefore, as in the above-mentioned first embodiment, by forming the concave-convex on the boiling surface 13, the generation rate of the bubble BG can be increased and the occurrence of local drying up can be suppressed.

[0154] The other effects of the second embodiment are the same as those of the above-mentioned first embodiment.

[0155] (First Modification of Second Embodiment)

[0156] refer to Fig.24 A first modification of the second embodiment will be described. In this first modification, unlike the second embodiment in which the mounting portion 11 is joined to the main body 214 by welding, an example in which the mounting portion 11 is joined to the main body 214 by brazing will be described.

[0157] like Fig.24 As shown, the process of joining the mounting portion 11 to the main body 214 includes the process of joining the mounting portion 11 to the main body 214 by brazing. At this time, a brazing plate 230 having a core material and a brazing material arranged on both sides of the core material is provided between the main body 214 and the mounting portion 11. The mounting portion 11 is brazed to the main body 214 via the brazing plate 230. The accommodating portion 212 is formed by brazing the mounting portion 11 to the main body 214. Thus, the boiling portion 210 is formed, and the cooler 200 is completed. In addition, the heating element HS is installed on the mounting surface 11a of the mounting portion 11.

[0158] (Second Modification of Second Embodiment)

[0159] refer to Fig.25 A second modification of the first embodiment will be described. In the second modification, unlike the first embodiment in which the mounting portion 11 is joined to the main body 214 by welding, an example in which the mounting portion 11 is joined to the main body 214 by screwing will be described.

[0160] like Fig.25 As shown, the process of joining the mounting portion 11 to the main body 214 includes the process of joining the mounting portion 11 to the main body 214 by screwing. At this time, a through hole for the screw 240 is provided in the mounting portion 11, and a threaded hole for the screw 240 is provided in the main body 214. In addition, a sealing component 250 such as an O-ring is provided between the main body 214 and the mounting portion 11. With the sealing component 250 sandwiched therebetween, the mounting portion 11 is screwed to the main body 214 by means of the screw 240. Thus, the housing portion 212 is formed and the boiling portion 210 is formed, so that the cooler 200 is completed. In addition, in the case of screwing, the refrigerant 5 can also be sealed in the housing portion 212 by means of the sealing component 250. In addition, the heating element HS is mounted on the mounting surface 11a of the mounting portion 11.

[0161] [Modifications]

[0162] In addition, it should be understood that the embodiments disclosed this time are illustrative in all aspects and are not restrictive. The scope of the present invention is indicated by the claims rather than the description of the above embodiments, and includes all changes (modifications) within the meaning and scope equivalent to the claims.

[0163] For example, the first and second embodiments above show a horizontal type boiling cooler with a horizontal boiling surface, but the present invention is not limited thereto. The boiling cooler of the present invention may also be a vertical type with a vertical boiling surface. Furthermore, the boiling coolers of the first and second embodiments above are only examples, and the shapes or configurations of the various parts of the boiling cooler are not particularly limited.

[0164] Furthermore, the first and second embodiments above show an example of setting one boiling surface 13, but the present invention is not limited thereto. In the present invention, a plurality of boiling surfaces 13 may be provided. A plurality of heating elements HS may be provided on the mounting surface 11a. In this case, a boiling surface 13 may be provided corresponding to one heating element HS (in the region FP), or a boiling surface 13 having a surface area corresponding to a plurality of heating elements HS may be provided.

[0165] The first embodiment (reference Figure 4) shows an example in which the direction (direction A) in which the first groove portion 14a extends is orthogonal to the direction (B) in which the second groove portion 14b extends, but the present invention is not limited thereto. The direction (direction A) in which the first groove portion 14a extends is not orthogonal to the direction (B) in which the second groove portion 14b extends. The first groove portion 14a and the second groove portion 14b may extend in any direction or may intersect at any angle.

[0166] The first embodiment (reference Fig. 9 ) shows an example in which the first region 17a and the second region 17b are arranged in a straight line, but the present invention is not limited to this. The first region 17a and the second region 17b may be arranged in a grid shape, for example. Fig. 9 In the examples (C) and (D), the first region 17a is shown as an example in which the first region 17a protrudes relative to the second region 17b (becomes a convex portion), but the first region 17a may be a concave portion (a concave portion) that is recessed relative to the second region 17b. Fig. 9 As in the examples (C) and (D), a groove structure 17 may be provided on the boiling surface portion 13 , and groove portions 14 may be formed on both the top surface (part of the first region 17a ) and the bottom surface (part of the second region 17b ) of the groove structure 17 .

[0167] In the first and second embodiments, the energy beam EB is an example of a laser beam, but the present invention is not limited thereto. In the present invention, the energy beam EB may be an electron beam or an ion beam.

[0168] Explanation of symbols

[0169] 5-refrigerant, 10, 210-boiling part, 11a-installation surface, 11b-surface, 12c-connecting part, 13-boiling surface part, 14-groove part, 14a-first groove part, 14b-second groove part, 15a, 15b, 15c-space part, 16a-bottom, 17a-first area, 17b-second area, 20, 220-condensation part, 100, 200-cooler (boiling cooler), HS-heating element, EB-energy beam, W1-opening width of the groove part, W2-width of the bottom part.

Claims

1. A boiling cooler, comprising: a boiling part that boils the refrigerant by exchanging heat with the heating element; and a condensing section for condensing the refrigerant vaporized in the boiling section and returning the refrigerant to the boiling section, The boiling portion includes a mounting surface of the heating element and a boiling surface portion provided on a side opposite to the mounting surface and in contact with the refrigerant. The boiling surface portion includes a groove portion extending in a linear shape and having an irregular concavo-convex shape formed as the material is melted and solidified by energy beam processing.

2. The boiling cooler according to claim 1, wherein: The groove portion includes a space portion, which is composed of at least any one of a hole portion opening in the boiling surface portion, a hollow portion in which at least a portion of the opening portion in the hole portion is covered, a horizontal hole portion extending laterally from the hole portion or the hollow portion, and a tunnel-shaped portion in which a portion of the opening of the groove portion is covered.

3. The boiling cooler according to claim 2, wherein: The space portion is a structure partially formed in a portion of the groove portion.

4. The boiling cooler according to any one of claims 1 to 3, wherein: At least a portion of the groove portion has a bottom portion having a width wider than an opening width of the groove portion in a cross section perpendicular to an extending direction of the groove portion.

5. The boiling cooler according to any one of claims 1 to 3, wherein: A plurality of the grooves are formed on the boiling surface portion, The plurality of grooves include: A plurality of first grooves extending along the boiling surface portion in a first direction; and The plurality of second grooves extend along the boiling surface portion in a second direction different from the first direction and intersect the plurality of first grooves.

6. The boiling cooler according to claim 5, wherein: The boiling section has a communication portion for allowing the refrigerant to flow between the boiling section and the condensing section. The first direction is a direction from the boiling surface portion toward the communicating portion in the boiling portion. The number of the first groove portions is greater than the number of the second groove portions.

7. The boiling cooler according to any one of claims 1 to 3, wherein: The boiling facial contains: a plurality of first regions, in which the grooves are formed; and The second region is arranged between the plurality of first regions and has no groove portion formed therein.

8. The boiling cooler according to claim 7, wherein: On the boiling surface, the plurality of first areas and the plurality of second areas are arranged alternately. Each of the plurality of first regions is formed in a step shape offset in a thickness direction of the boiling surface portion relative to the adjacent second region.

9. The boiling cooler according to any one of claims 1 to 3, wherein: The groove portion has a maximum opening width of 1 μm or more and less than 1 mm.

10. A method for manufacturing a boiling cooler, the boiling cooler comprising: a boiling part that boils the refrigerant by exchanging heat with the heating element; and a condensing section for condensing the refrigerant vaporized in the boiling section and returning the refrigerant to the boiling section, The manufacturing method of the boiling cooler comprises the following steps: forming the condensation portion; and The boiling portion is formed, the boiling portion including a mounting surface of the heating element and a boiling surface portion provided on a side opposite to the mounting surface and in contact with the refrigerant, The process of forming the boiling part includes the following steps: The boiling surface portion is irradiated with an energy beam in a linear pattern to perform groove processing, thereby forming a groove portion having an irregular concave-convex shape formed along with melting and solidification of the material due to the energy beam processing on the boiling surface portion.

Images