JP2013007501A - Cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device that suppresses deterioration of cooling performance.SOLUTION: The cooling device includes: an evaporation unit connected with a heating element; a condensation unit connected with a heat releasing unit; and a refrigerant evaporated at the evaporation unit and condensed at the condensation unit, wherein the condensation unit has an uneven structure on a surface where it connects thermally with the heat releasing unit.

Description

  The present invention relates to a cooling device that absorbs heat and dissipates heat by phase change of a refrigerant.

  A semiconductor element with a large calorific value is provided with a heat sink at the top of the package of the semiconductor element to expand the heat transfer surface, and forced air cooling is performed on the heat transfer surface expanded by a blower or the like to reduce the heat generated by the semiconductor element. Cooling was taking place.

  2. Description of the Related Art In recent years, electronic devices have been made thinner and smaller along with advances in mounting technology and multilayered printed circuit boards. Therefore, it is difficult to secure a space for a cooling component such as a heat sink above the semiconductor package used in the electronic device.

  Therefore, boiling cooling provided with an evaporating part and a condensing part that fills the inside of a metal housing having a sealed space, evaporates by boiling the refrigerant with heat generated from the heating element, and transports heat by the evaporated refrigerant. Research on vessels is progressing.

  In the boiling cooler, the refrigerant vapor evaporated by the heat of the heating element circulates in the enclosure and moves to the condensing part by utilizing the volume difference and capillary phenomenon of gas and liquid, and buoyancy due to the difference of gas and liquid density. To do. Then, the refrigerant in the condensing unit is cooled by exchanging heat with the outside air, the evaporated refrigerant is condensed from gas to liquid, and the heat generated in the heating element is radiated to the outside air.

  Patent Document 1 describes a specific structure of a flat plate type cooling device. A flow path structure is provided in a sealed space formed of a silicon substrate. By forming the width of the grooves that make up the flow channel structure in the order of the liquid phase flow channel, the evaporation flow channel, and the gas phase flow channel, circulation of the working fluid is promoted and heat transport efficiency is improved. ing.

JP 2004-353902 A

  However, in the cooling device described in Patent Document 1, the refrigerant liquefied in the condensing flow path, which is a condensing part of the cooling device, adheres to the inner wall surface of the casing to form a condensed liquid film. Since the thermal conductivity of the refrigerant is smaller than the thermal conductivity of the metal constituting the casing, there is a problem that the heat exchange performance between the casing and the refrigerant is deteriorated and the cooling performance is lowered.

  An object of this invention is to provide the cooling device which solves the said subject.

  The cooling device in the present invention includes an evaporation unit to which a heating element is connected, a condensing unit to which a heat radiating unit is connected, and a refrigerant that is vaporized in the evaporating unit and condensed in the condensing unit. The surface to be connected is provided with a concavo-convex structure.

  According to the cooling device of the present invention, it is possible to suppress a decrease in cooling performance.

It is a block diagram which shows the structure of the cooling device in 1st Embodiment. It is a perspective view which shows the structure of the cooling device in 2nd Embodiment. It is an exploded view which shows the structure of the cooling device in 2nd Embodiment. It is sectional drawing which shows the structure of the cooling device in 2nd Embodiment. It is sectional drawing which shows the structure of the cooling device in 2nd Embodiment. It is sectional drawing which shows the structure of the cooling device in 2nd Embodiment. It is sectional drawing which shows the structure of the cooling device in 2nd Embodiment. It is sectional drawing which shows the structure of the cooling device in 3rd Embodiment. It is sectional drawing which shows the structure of the cooling device in 4th Embodiment.

  Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. However, the preferred embodiments described below are technically preferable for carrying out the present invention, but the scope of the invention is not limited to the following.

  [First Embodiment] This embodiment will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a cooling device 1 according to the present embodiment.

  [Description of Structure] As shown in FIG. 1, the cooling device 1 according to the present embodiment includes a condensing unit 20, an evaporating unit 30, a refrigerant 5, and an uneven structure forming unit 60.

  A heat radiating unit is connected to the condensing unit 20, and a heating element is connected to the evaporation unit 30. The condensing unit 20 includes a concavo-convex structure forming unit 60 on the surface thermally connected to the heat radiating unit. The evaporation unit 30 is filled with the refrigerant 5.

  In FIG. 1, the flat plate-type cooling device 1 is shown, but the invention is not limited to this, and the condensing unit 20 and the evaporating unit 30 are provided in separate devices, and the refrigerant 5 is circulated by connecting each other by piping or the like. It is good also as a structure.

  The refrigerant 5 in the evaporation unit 30 boils and vaporizes due to the amount of heat from the heating element. The vapor | steam of the vaporized refrigerant | coolant 5 is conveyed to the condensation part 20 by the buoyancy by the difference in gas-liquid density. The vapor | steam of the refrigerant | coolant 5 conveyed to the condensation part 20 is condensed and liquefied by being cooled by the thermal radiation part. The condensed refrigerant 5 descends due to gravity and recirculates.

  [Explanation of Effects] The cooling device 1 in the present embodiment includes the concavity and convexity structure forming unit 60 in the condensing unit 20. The concavo-convex structure forming portion 60 includes a concave portion and a convex portion, and the temperature of the concave portion is low because the distance from the heat radiating portion is shorter than that of the convex portion. As a result, a condensed liquid film is formed on the refrigerant 5 in contact with the concave portion, but the condensed liquid film is not formed on the convex portion although the refrigerant 5 is condensed. Therefore, in the convex part, it is possible to prevent the cooling performance of the cooling device 1 from being lowered due to the formation of the condensed liquid film.

  [Second Embodiment] This embodiment will be described in detail with reference to the drawings. 2 is a perspective view showing a configuration of the cooling device 1 in the present embodiment, FIG. 3 is an exploded perspective view, and FIG. 4 is a cross-sectional view.

  [Description of Structure] As shown in FIGS. 2 and 3, the cooling device 1 in this embodiment is constituted by a flat container 2 that houses a condensing unit 20 and an evaporating unit 30. The cooling device 1 is used by thermally connecting the heat radiating unit 3 to the condensing unit 20 and the heating element 4 to the evaporating unit 30.

  As shown in FIGS. 2 and 3, the flat container 2 has a box shape and has a sealed space inside. The flat container 2 may be configured by assembling two members as shown in FIG. 3, may be configured by combining a plurality of components, or may be integrally formed.

  When the plate-shaped container 2 is constructed by assembling members such as metal plates separately created, the connections such as joints of the metal plates are sealed with a resin such as silicone rubber so that water and dust do not enter from the outside. Use a sealed structure. The material of the flat container 2 is made of a material having high thermal conductivity such as copper or aluminum.

  The flat container 2 and the heating element 4 are thermally connected through an adhesive having high thermal conductivity such as thermal conductive grease.

  As shown in FIG. 4, the refrigerant 5 is sealed in the sealed space inside the flat container 2. Specific examples of the refrigerant 5 include HFC (hydro fluorocarbon), HFE (hydro fluorether), water, and the like, but the material is not limited thereto.

  The partial pressure of the refrigerant 5 in the sealed space inside the flat container 2 maintains the saturated vapor pressure in a state where the partial pressure is reduced from the atmospheric pressure using a pump or the like. Since the refrigerant 5 has a low boiling point, the boiling point of the refrigerant 5 can be lowered to about 30 degrees by reducing the pressure. As a result, the refrigerant 5 can be boiled by the heat generated by the heating element 4.

  As shown in FIG. 5, the flat container 2 has a heat radiating portion 3 on the outer surface of the condensing portion 20. FIG. 5 shows a cross-sectional view. Since the condensing unit 20 is provided vertically upward with respect to the evaporation unit 30, the heat radiating unit 3 is also provided vertically upward with respect to the heating element 4.

  The surface on which the heat radiating section 3 is provided on the flat container 2 may be the same surface as the surface on which the heat generating element 4 is attached, or may be the opposite surface opposite to the surface on which the heat generating element 4 is attached. . (In FIGS. 2 and 3, the case where the heat radiating portion 3 is provided on the same surface as the surface on which the heating element 4 is attached is shown.) Note that a plurality of heating elements 4 are provided and provided on a plurality of surfaces of the flat container 2. Also good. The heat dissipating part 3 is not particularly limited as long as it has a fin shape, a large surface area, and a material having high thermal conductivity such as copper and aluminum.

  As shown in FIGS. 3 and 4, the flat container 2 includes the concavo-convex structure 6 in the concavo-convex structure forming part 60 which is a part of the inner wall surface in the region where the heat radiating part 3 is arranged. The concavo-convex structure 6 includes a concave portion 6a and a convex portion 6b, and the concave portion 6a is thinner than the convex portion 6b and other wall surfaces. (Although not shown, the convex portion 6b may be formed thicker than the concave portion 6a and other wall surfaces.) The number, size, and depth of the concave portion 6a and the convex portion 6b are particularly limited. Not.

  The concavo-convex structure 6 is formed on the inner wall surface of the flat container 2 at least a part of which is thermally connected to the heat radiating part 3, and the heat radiating part 3 and the concavo-convex structure 6 are arranged via the flat container 2, At least a part is facing. Since the recess 6a in the concavo-convex structure 6 is thinner than the other portions, the distance from the heat radiating portion 3 is short. As a result, the concave portion 6a easily transmits heat to the heat radiating portion 3, and the temperature is lower than the inner wall of the other flat container 2.

  In the concavo-convex structure 6, as shown in FIG. 4, the concave portion 6a and the convex portion 6b of the concavo-convex structure 6 may be provided by extending in a predetermined direction in a groove shape, or as shown in FIG. Or the convex part 6b is comprised by the hole part of a hole shape, and may be scattered and provided.

  [Description of Functions and Effects] Next, functions and effects in this embodiment will be described.

  The flat container 2 is made of a material having high heat conductivity such as copper or aluminum, and is thermally connected to the heating element 4 via heat conductive grease. Therefore, the heat generated by the heating element 4 is transmitted to the refrigerant 5 provided inside the flat container 2 through the flat container 2.

  The gas-liquid interface of the refrigerant 5 provided in the sealed space inside the flat container 2 is higher than the height at which the heating element 4 is attached, and higher than the height at which the heat dissipating section 3 and the uneven structure 6 are arranged. The amount of the refrigerant 5 is adjusted so as to be at a low position. The amount of the refrigerant 5 is adjusted so that the entire sealed space is not filled with the refrigerant 5.

  The refrigerant 5 boils by receiving the heat generated by the heating element 4. The vapor | steam of the refrigerant | coolant 5 which generate | occur | produced when the refrigerant | coolant 5 provided in the sealed space of the flat container 2 boils is conveyed to the upper part of the flat container 2 by the buoyancy by the difference in gas-liquid density.

  The vapor of the refrigerant 5 carried to the upper part of the flat container 2 exchanges heat with the outside air by the heat radiating unit 3 thermally connected to the flat container 2 via the flat container 2. The heat radiation part 3 can enlarge a surface area by making it fin shape, and can perform heat exchange with outside air efficiently.

  The vapor of the refrigerant 5 provided in the flat container 2 thermally connected to the heat radiating unit 3 is cooled and condensed. The liquefied refrigerant 5 descends in the flat container 2 due to gravity and returns to the gas-liquid interface of the refrigerant 5. And the refrigerant | coolant 5 boils with the heat | fever which the heat generating body 4 generate | occur | produces again, and a cooling cycle is performed continuously.

  In other words, the refrigerant 5 provided in the flat container 2 changes from liquid to gas by the heat generated by the heating element 4, and is condensed via the heat radiating unit 3 to condense from gas to liquid again. . That is, the refrigerant 5 radiates the heat generated by the heating element 4 through the heat radiating unit 3 by repeating the phase change from liquid to gas and from gas to liquid.

  However, in the case of the cooling device 1 that does not have the uneven structure 6 on the inner wall of the flat container 2 as shown in FIG. 6, the refrigerant 5 cooled and condensed by the heat radiating unit 3 is As a result, the condensate film 10 is formed. Since the condensate film 10 formed by surface tension on the inner wall surface of the flat container 2 exists between the flat container 2 cooled by the heat radiating unit 3 and the vapor of the refrigerant 5, the heat exchange rate between the two is changed. It will decrease.

  More specifically, as shown in FIG. 6, when the refrigerant 5 is condensed on the inner wall of the flat container 2 by the cooling of the heat radiating unit 3 and the condensed liquid film 10 is formed by surface tension, the cooled flat plate shape is formed. The container 2 and the vapor | steam of the refrigerant | coolant 5 cannot contact directly. Therefore, when the condensate liquid film 10 is formed on most of the flat container 2 cooled by the heat radiating unit 3, the vapor of the refrigerant 5 needs to exchange heat with the flat container 2 through the condensate liquid film 10.

  However, since the refrigerant 5 has a lower thermal conductivity than the flat container 2, when the condensate film 10 of the refrigerant 5 is formed between the vapor of the refrigerant 5 and the flat container 2, the refrigerant 5 The heat exchange performance with the flat container 2 is lowered, and the cooling performance is also lowered. As a result, it becomes difficult to continuously perform a cooling cycle in which the vapor of the refrigerant 5 is condensed and liquefied.

  On the other hand, in the cooling device 1 according to the present embodiment, the concavo-convex structure 6 is provided on the inner wall surface of the flat container 2 in which the heat radiating unit 3 is provided. As shown in FIG. 7, when the flat container 2 is cooled by the heat radiating unit 3, the vapor of the refrigerant 5 is condensed on the inner wall surface of the flat container 2. Then, a condensation film 10 is formed on the bottom surface of the recess 6 a of the concavo-convex structure 6 formed on the inner wall surface of the flat container 2.

  If it demonstrates in detail, since the distance between the recessed parts 6a of the uneven structure 6 and the thermal radiation part 3 differs compared with the circumference | surroundings including the convex part 6b, a temperature difference arises. That is, since the distance between the recess 6a and the heat radiation part 3 is shorter than the protrusion 6b, the temperature is lowered. Therefore, when the vapor | steam of the refrigerant | coolant 5 condenses within the recessed part 6a, the condensed liquid film | membrane 10 will be formed.

  On the other hand, even if the vapor | steam of the refrigerant | coolant 5 condenses in the convex part 6b, since the distance from the thermal radiation part 3 is long compared with the recessed part 6a, since temperature is higher than the recessed part 6a, the condensed liquid film 10 is hard to be formed. Even if it is a case where it condenses in the convex part 6b, a condensate falls to the downward direction of a vertical direction with gravity, and flows into the recessed part 6a. Therefore, the condensed film 10 is not formed on the convex portion 6b. On the other hand, the condensate film 10 is formed in the recess 6a because the temperature is lower than that of the protrusion 6b.

  When the thickness of the condensate film 10 in the recess 6a exceeds the depth of the recess 6a, the condensate overflows from the recess 6a, flows on the protrusion 6b, and flows into the recess 6a arranged downward in the vertical direction. Then, the condensate liquid film 10 is further cooled in the recess 6a, and then recirculates to the gas-liquid interface at the lower part of the flat container 2.

  That is, even if the vapor of the refrigerant 5 condenses in the convex portion 6b, the condensed film flows into the concave portion 6a without forming the condensation film 10 in the convex portion 6b. Therefore, the vapor | steam of the refrigerant | coolant 5 and the convex part 6b of the flat container 2 cooled by the thermal radiation part 3 can contact | connect directly, without passing through the condensed liquid film | membrane 10. FIG. As a result, the cooling cycle of the boiling cooling system is continuously performed in which the vapor of the refrigerant 5 that has received the heat generated by the heating element 4 and boiled is cooled through the heat radiating unit 3 to be condensed and liquefied again. Can do.

  [Third Embodiment] Next, a third embodiment will be described in detail with reference to the drawings. FIG. 8 is a cross-sectional view of the cooling device 1 in the present embodiment.

  [Description of Structure] The cooling device 1 in the present embodiment includes a groove-shaped portion 7 formed by extending in a direction inclined with respect to the vertical direction. Other structures and connection relationships are the same as those in the first embodiment, and include a flat container 2, a heating element 4 in the evaporation unit 30, and a heat dissipation unit 3 in the condensing unit 20.

  The groove-shaped portion 7 is formed on the inner wall of the flat container 2 and includes a groove-shaped recess 7a and a groove-shaped protrusion 7b. The groove-type recess 7a has a shape that is thinner than the groove-shaped protrusion 7b and the surrounding wall surface. That is, the distance between the groove-shaped recess 7a and the heat radiation part 3 is shorter than that of the groove-shaped protrusion 7b. The groove-shaped portion 7 is formed by extending in a direction inclined with respect to the vertical direction.

  The groove-shaped portion 7 is provided on the inner wall surface of the flat container 2 that is thermally connected to the heat radiating portion 3. Since the groove-shaped concave portion 7a is thinner than other portions, the efficiency of heat conduction with the heat radiating portion 3 is higher than that of the other portions. The number, size, and depth of the groove-type concave portions 7a and the groove-shaped convex portions 7b are not particularly limited.

  [Description of Functions and Effects] Next, functions and effects in this embodiment will be described.

  The refrigerant 5 provided in the flat container 2 boils by receiving heat generated by the heating element 4. The vapor | steam of the refrigerant | coolant 5 which generate | occur | produced when the refrigerant | coolant 5 boils is conveyed to the upper part of the flat container 2 by the buoyancy by the difference in gas-liquid density. In addition, the gas-liquid interface of the refrigerant | coolant 5 provided in the airtight space inside the flat container 2 is higher than the height to which the heat generating body 4 is attached, and the heat dissipating part 3 and the groove-shaped part 7 are disposed. The amount of the refrigerant 5 is adjusted so that the position is lower than that. The amount of the refrigerant 5 is adjusted so that the entire sealed space is not filled with the refrigerant 5.

  The vapor of the refrigerant 5 carried to the upper part of the flat container 2 exchanges heat with the outside air by the heat radiating unit 3 thermally connected to the flat container 2 via the flat container 2. When the heat radiating unit 3 is cooled, the vapor of the refrigerant 5 inside the flat container 2 is also cooled and condensed on the inner wall of the flat container 2.

  Since the groove-shaped recess 7a of the groove-shaped portion 7 formed on the inner wall of the flat container 2 has a shape formed in the flat shape in the flat container 2, the thickness of the flat container 2 is thinner than the convex portion. For this reason, the groove-shaped recess 7a is close to the heat dissipating part 3 and has a low temperature. And if the vapor | steam of the refrigerant | coolant 5 condenses in the groove-type recessed part 7a, the condensed liquid film | membrane 10 will be formed.

  On the other hand, when condensation of the refrigerant 5 occurs in the groove-shaped convex portion 7b, the distance from the heat radiating portion 3 is longer than that of the groove-shaped concave portion 7a, so that the temperature of the condensed liquid film 10 is less likely to be formed. . The condensate condensed in the groove-shaped convex portion 7b moves downward in the vertical direction due to gravity and flows into the groove-shaped concave portion 7a, and forms a condensate film 10 in the groove-shaped concave portion 7a whose temperature is lower than that of the groove-shaped convex portion 7b. To do. That is, since the condensing film 10 is not formed on the groove-shaped convex portion 7 b, the groove-shaped convex portion 7 b of the flat container 2 cooled by the vapor of the refrigerant 5 and the heat radiating portion 3 does not directly pass through the condensate liquid film 10. Can touch.

  Here, for example, consider a case where the groove-shaped portion 7 is formed by extending in a direction parallel to the vertical direction. When the groove-shaped portion 7 is formed by extending in the vertical direction, the condensate formed in the groove-shaped recess 7a of the groove-shaped portion 7 can be circulated to the gas-liquid interface at the lower part of the flat plate container 2 at the shortest distance. it can.

  However, in the above configuration, the area where the condensate formed in the groove-shaped recess 7a and the heat dissipating part 3 are small, and the condensate falls directly below the flat container 2 due to gravity. The cooling time is short. As a result, it is difficult to keep the temperature of the condensate formed in the groove-type recess 7a low.

  On the other hand, consider the case where the groove-shaped portion 7 is formed by extending in a direction perpendicular to the vertical direction. In this case, since the part where the groove-shaped part 7 faces the heat radiating part 3 can be provided long, the temperature of the condensate can be kept low. Further, when the thickness of the condensate film 10 formed in the groove-shaped recess 7a exceeds the groove-shaped recess 7a, the condensate flows and moves on the groove-shaped protrusion 7b and is disposed downward in the vertical direction. It returns to the mold recess 7a or the gas-liquid interface.

  However, in the case of the above configuration, when the condensate film 10 formed in the groove-shaped recess 7a overflows from the groove-shaped recess 7a, a part of the condensate flows on the groove-shaped protrusion 7b. The condensate is provided between the container 2 and the heat exchange rate of the two may decrease, leading to a decrease in cooling performance.

  Therefore, the groove-shaped portion 7 of the cooling device 1 in the present embodiment is formed by extending in a direction inclined with respect to the vertical direction. Therefore, the condensate liquid film 10 formed in the groove-type recess 7a flows along the direction inclined in the direction of gravity in the groove-type recess 7a.

  At the end of the groove-type recess 7a, the condensate overflows from the groove-type recess 7a and returns to the gas-liquid interface provided at the lower part of the flat container 2. For this reason, it is possible to prevent the condensate film 10 formed in the groove-shaped recess 7a from overflowing from the groove-shaped recess 7a and flowing through the groove-shaped protrusion 7b except at the end of the groove-shaped recess 7a. Then, the condensate moves through the groove-type recess 7 a along the direction inclined in the vertical direction, and reaches the lower part of the flat container 2.

  Thus, since the groove-shaped portion 7 is formed by extending in a direction inclined with respect to the vertical direction, a portion where the groove-shaped portion 7 and the heat radiating portion 3 are opposed to each other can be provided long. The temperature can be kept low. As a result, the refrigerant 5 condensed in the groove-shaped convex portion 7b is discharged through the groove-shaped concave portion 7a, so that the condensed liquid film 10 is hardly formed.

  As described above, the vapor of the refrigerant 5 and the groove-shaped convex portion 7 b of the flat container 2 can be in direct contact with each other without using the condensate liquid film 10. As a result, the cooling cycle of the boiling cooling system is continuously performed in which the vapor of the refrigerant 5 that has received the heat generated by the heating element 4 and boiled is cooled through the heat radiating unit 3 to be condensed and liquefied again. Can do.

  [Fourth Embodiment] Next, a fourth embodiment will be described in detail with reference to the drawings. FIG. 9 is a cross-sectional view of the cooling device 1 in the present embodiment.

  [Description of Structure] In the cooling device 1 according to this embodiment, the groove-shaped portion 7 is composed of a horizontal groove portion 8 and a vertical groove portion 9. The other structure is the same as that of the first embodiment, and is provided with a flat container 2 and is used by thermally connecting the heating element 4 in the evaporation unit 30 and the heat radiation unit 3 in the condensing unit 20.

  The groove-shaped portion 7 in the present embodiment is formed by extending in a direction perpendicular to the vertical direction, that is, the horizontal groove portion 8 extending in the horizontal direction, and in a direction parallel to the vertical direction. It is comprised with the vertical groove part 9. FIG. A plurality of the horizontal groove portions 8 and the vertical groove portions 9 are provided, and are formed in a groove shape on the inner wall of the flat container 2.

  The horizontal groove portion 8 is composed of a plurality of horizontal concave portions 8a and a plurality of horizontal convex portions 8b, and each is arranged in a direction perpendicular to the vertical direction. Similarly, the vertical groove portion 9 is composed of a plurality of vertical concave portions 9a and vertical convex portions 9b, and is arranged side by side in a direction parallel to the vertical direction. The horizontal groove portion 8 and the vertical groove portion 9 are connected so as to cross each other.

  A plurality of horizontal groove portions 8 arranged adjacent to each other are connected via a vertical groove portion 9. Similarly, the plurality of vertical groove portions 9 arranged adjacent to each other are connected via the horizontal groove portion 8. Note that the number, size, and depth of the horizontal grooves 8 and the vertical grooves 9 are not particularly limited.

  [Description of Functions and Effects] Next, functions and effects in this embodiment will be described.

  The refrigerant 5 provided in the flat container 2 boils by receiving the heat generated by the heating element 4, and the vapor of the refrigerant 5 generated by boiling boiles due to the buoyancy due to the difference in gas-liquid density. It is carried to the upper part of the container 2. Note that the gas-liquid interface of the refrigerant 5 provided in the sealed space inside the flat container 2 is higher than the height at which the heating element 4 is attached, and the heat radiating part 3, the horizontal groove part 8, and the vertical groove part 9 are arranged. The amount of the refrigerant 5 is adjusted so that the position is lower than the height at which it is located.

  The vapor of the refrigerant 5 carried to the upper part of the flat container 2 exchanges heat with the outside air by the heat radiating unit 3 thermally connected to the flat container 2 via the flat container 2. When the heat radiating unit 3 is cooled, the vapor of the refrigerant 5 inside the flat container 2 is also cooled and condensed on the inner wall of the flat container 2.

  In the horizontal recess 8a and the vertical recess 9a formed in the shape of a groove on the inner wall of the flat container 2, the thickness of the flat casing 2 is thinner than the horizontal protrusion 8b and the vertical protrusion 9b. Therefore, the distance between the horizontal recess 8a and the vertical recess 9a is short and the temperature tends to be low. As a result, the vapor | steam of the refrigerant | coolant 5 forms the condensed liquid film 10 in the horizontal recessed part 8a and the vertical recessed part 9a.

  On the other hand, when the refrigerant vapor condenses in the horizontal convex portion 8b and the vertical convex portion 9b, the distance from the heat radiating portion 3 is longer than the horizontal concave portion 8a and the vertical concave portion 9a. The condensed liquid film 10 is difficult to be formed.

  Then, the condensate condensed in the horizontal convex portion 8b and the vertical convex portion 9b moves downward in the vertical direction due to gravity, flows into the horizontal concave portion 8a and the vertical concave portion 9a, and condensate film 10 in the concave portion 6a whose temperature is lower than that of the convex portion 6b. Form. That is, no condensate film is formed on the horizontal convex part 8b or the vertical convex part 9b, so that the vapor of the refrigerant 5 can be in direct contact with the horizontal convex part 8b and the vertical convex part 9b without the condensed liquid film 10.

  Since the horizontal groove portion 8 has a long portion facing the heat radiating portion 3, the condensate formed in the horizontal recess 8 a moves in the horizontal direction and dissipates heat through the heat radiating portion 3, so that the temperature of the condensate is reduced. Can be lowered. In addition, since the horizontal recessed part 8a and the vertical recessed part 9a are connected, the condensate cooled in the horizontal recessed part 8a flows into the vertical recessed part 9a.

  On the other hand, the vertical groove portion 9 has a short portion facing the heat radiating portion 3 but is formed in parallel to the vertical direction. Therefore, the condensate liquid film 10 formed in the vertical concave portion 9a follows the gravity direction. Thus, the refrigerant can be refluxed to the gas-liquid interface of the refrigerant 5 below the flat container 2.

  And in the lower end part of the vertical recessed part 9a, a condensate flows out of the vertical recessed part 9a, and recirculate | refluxs to the gas-liquid interface provided in the flat container 2 lower part. That is, the condensate film 10 formed in the vertical recess 9a can be prevented from overflowing from the vertical recess 9a and flowing through the vertical protrusion 9b except at the end of the vertical recess 9a.

  With the above configuration, the vapor of the refrigerant 5 can be in direct contact with the horizontal convex portion 8 b and the vertical convex portion 9 b without using the condensate liquid film 10. As a result, a cooling cycle of a boiling cooling system in which the vapor of the refrigerant 5 that has received the heat generated by the heating element 4 and boiled is cooled through the heat radiating unit 3 to condense the refrigerant 5 and liquefy it again. Can be done continuously.

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Flat container 3 Heat radiating part 4 Heat generating body 5 Refrigerant 6 Uneven structure 6a Concave part 6b Convex part 7 Grooved part 7a Groove type concave part 7b Groove type convex part 8 Horizontal groove part 8a Horizontal concave part 8b Horizontal convex part 9 Vertical groove part 9a Vertical concave portion 9b Vertical convex portion 10 Condensed liquid film 20 Condensing portion 30 Evaporating portion 60 Uneven structure forming portion

Claims (12)

An evaporation section to which a heating element is connected;
A condensing part to which the heat dissipating part is connected;
A refrigerant that evaporates in the evaporation section and condenses in the condensation section,
The said condensation part is a cooling device provided with the uneven structure in the surface thermally connected with the said thermal radiation part.   The cooling device according to claim 1, wherein the uneven structure includes a groove-shaped portion provided on an inner wall surface constituting the condensing portion.   The cooling device according to claim 1, wherein the concavo-convex structure includes a hole provided in an inner wall surface constituting the condensing unit.   The cooling device according to claim 2, wherein the groove-shaped portion is arranged extending in a direction inclined with respect to the vertical direction. The groove-shaped part is
A horizontal groove formed by extending in a direction perpendicular to the vertical direction;
A vertical groove formed by extending in a direction parallel to the vertical direction,
The cooling device according to claim 2, wherein the vertical groove portion and the vertical groove portion are connected to each other. A flat container that accommodates the evaporating unit and the condensing unit,
The cooling device according to claim 1, wherein the refrigerant circulates inside the flat container.   The cooling device according to claim 1, further comprising a pipe connecting the evaporating unit and the condensing unit, wherein the refrigerant circulates through the pipe.   The cooling device according to claim 1, wherein the condensing unit is arranged vertically above the evaporation unit.   The cooling device according to any one of claims 1 to 8, wherein a gas-liquid interface of the refrigerant is located between the evaporation unit and the condensing unit.   The cooling device according to claim 1, wherein a material of the refrigerant includes any one of hydrofluorocarbon, hydrofluoroether, or water.   The cooling apparatus according to any one of claims 1 to 10, wherein a material of the flat container is any one of copper and aluminum.   The cooling device according to any one of claims 1 to 11, wherein a partial pressure of the refrigerant is smaller than an atmospheric pressure.

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