JP2016133230A - Heat radiator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiator in which its installation space can be easily assured and a CPU and the like showing high heating density can be effectively cooled.SOLUTION: An evaporating part 11 stores a liquid refrigerant 14 in it. The evaporating part 11 has an evaporating surface 11a having the refrigerant 14 at its inner surface that can be evaporated with heat transmitted from a heater component 1 while being thermally contacted with it and the evaporating surface 11a is provided with a wick or a heat transmission promoting surface 11b. An inner surface of a condensing pipe 12 is provided with a heat transmission promoting surface 12a and the condensing pipe is installed in such a way that it may communicate with the inside part of the evaporating part 11 at an opposite side of the evaporating surface 11a. A plurality of heat radiation fins 13 are arranged to extend from the outer surface of the condensing pipe 12 toward the outside. When the condensing pipe 12 is arranged in horizontal orientation or inclined, it has a groove 12b formed to extend along an extending direction below the inner surface of the condensing pipe 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat dissipation device.

  In recent years, the heat generation density of computer CPUs has increased dramatically, and it is no exaggeration to say that how to cool the CPU determines the performance of the computer. The heat generated by the CPU is finally dissipated into the atmosphere, but the CPU temperature must be kept below about 90 ° C. How to cool a CPU with a high heat generation density under conditions where the temperature difference from the ambient temperature is small Is a problem. This is greatly different from the case where the temperature difference between the heat radiating medium and the heating surface can be made sufficiently large, such as the cooling of a reactor fuel rod having the same high heat generation density or the cooling of a rocket engine.

  Currently, CPUs of personal computers, data centers, and supercomputers are mainly cooled by air. For example, metal plate fins are brought into close contact with the CPU and cooled by flowing air therethrough. However, the cooling performance by this forced convection fin has reached its limit, and it is considered difficult to dramatically improve the cooling performance by this method in the future. For example, an electronic device having a high heat generation density cannot be handled by air cooling.

  On the other hand, since the amount of heat transport is large and it is possible to cool a high heat flux, CPU cooling using a phase change of a working medium has been attempted. In early supercomputers, there was a case where the CPU was cooled by immersing it directly in a refrigerant, but this is not currently adopted from the viewpoint of maintainability. In addition, there is a sheet-type heat pipe that is used for cooling a CPU of a laptop personal computer (see, for example, Patent Document 1). This sheet-like heat pipe is equipped with a wick that transports fluid with surface tension on the inner surface of the pipe, and a certain amount of working fluid is sealed in the pipe, and vapor transport in the pipe by evaporation is opposite to that steam transport. High-efficiency heat transport is performed by utilizing the liquid transport due to the surface tension of the liquid, and heat transport is possible regardless of the position of the pipe.

  Some thermosiphons are used to cool high heat flux devices such as power thyristors (see, for example, Patent Documents 2 to 4). In this thermosyphon, the heating part thermally connected to the heat radiating device is located in the lower part and the condensing part is located in the upper part. The liquid condensed in the condensing part falls by gravity and is transported to the lower heating part. And there is no limit to liquid transport capacity.

  In addition, in boiling heat transfer tubes used for heat exchangers, etc., a heat transfer promotion surface formed by providing a large number of fine grooves on the inner peripheral surface in order to promote heat exchange by reducing the thermal resistance due to boiling and condensation. Has been developed (see, for example, Patent Document 5).

JP 2013-174376 A Japanese Patent Application Laid-Open No. 2014-74568 JP 2010-80507 A JP 2007-198661 A JP-A-6-341785

  In the heat pipe as described in Patent Document 1, since there is a limit in the liquid transport capability of wicks and the like, there is a limit in cooling and transporting a large heat flux. Therefore, there is a problem that it is difficult to cool a CPU having a high heat generation density. Moreover, in the thermosiphon as described in Patent Documents 2 to 4, there is a problem that there is a case where the installation space cannot be secured because the positional relationship between the heating unit and the condensing unit is limited.

  The present invention has been made paying attention to such a problem, and an object of the present invention is to provide a heat dissipation device that can easily secure an installation space and can effectively cool a CPU having a high heat generation density. .

  In order to achieve the above object, a heat radiating device according to the present invention includes an evaporation section that stores a liquid refrigerant therein, a condensing pipe that is provided to communicate with the inside of the evaporating section, and an outer surface of the condensing pipe. A plurality of heat dissipating fins that extend from the outside to the outside, and the evaporation portion is in thermal contact with the heating element on the inner surface, and the refrigerant can be evaporated by the heat transmitted from the heating element The evaporation surface is provided with a wick or heat transfer promotion surface, and the condensation pipe is provided with a heat transfer promotion surface on the inner surface, and on the opposite side of the evaporation surface, the It is characterized by communicating with the inside of the evaporation section.

  The heat radiating device according to the present invention is used by being attached so that the evaporation surface of the evaporation section is in thermal contact with the heating element in order to cool the heating element such as a CPU having a high heat generation density. In the heat dissipating device according to the present invention, the refrigerant evaporates inside the evaporating part due to the heat transmitted from the heating element to the evaporation surface, and the vapor flows from the inside of the evaporating part toward the inside of the condenser tube. At this time, since the wick or the heat transfer promotion surface is provided on the evaporation surface, the boiling heat transfer resistance can be reduced and the refrigerant can be easily evaporated. In addition, even if the evaporation surface stands vertically or is inclined, the refrigerant spreads along the evaporation surface due to the capillary force generated on the wick or heat transfer promoting surface, so that the evaporation surface is prevented from being dried. Evaporation can be further promoted. The wick is formed by, for example, a wire mesh or fine grooves, and the heat transfer promotion surface is formed by providing a large number of fine grooves as described in Patent Document 5. Both the wick and the heat transfer promoting surface transport fluid by capillary force due to surface tension. It is preferable that the wick and the heat transfer promoting surface be provided so that, when in use, the extension direction of the groove serving as the source of capillary force is parallel to the gravity.

  When steam enters the condensing tube, the heat of the steam is released to the outside by the radiation fins, so that the steam condenses and returns to the liquid refrigerant. At this time, since the heat transfer promoting surface is provided on the inner side surface of the condensing tube, it is possible to reduce the thermal resistance at the time of condensing and make it easy to liquefy the vapor. As described above, the heat dissipating device according to the present invention can evaporate and condense with a high heat flux even with a low temperature difference, and can effectively cool a heating element such as a CPU having a high heat generation density. In addition, by arranging the condenser tube so as to be inclined downward or horizontally toward the evaporator, the condensed liquid refrigerant can be smoothly returned to the evaporator, and the refrigerant is continuously circulated to cool the heating element. It can be performed.

  The orientation of electronic devices such as computer systems is mostly horizontal or vertical, but conventional thermosiphons can only handle horizontal ones. On the other hand, the heat radiating device according to the present invention is not limited to a horizontal one, and can be adapted to a vertical one, and can be cooled regardless of the direction and arrangement of a heating element such as an electronic device. Moreover, since there is almost no restriction | limiting in arrangement | positioning of an evaporation part and a condensation pipe, compared with the conventional thermosiphon, it is easy to ensure installation space.

  In the heat radiating device according to the present invention, the refrigerant may be anything as long as it can evaporate and condense within the operating temperature range, and is made of, for example, water or alcohol. Further, it is preferable that the amount of the refrigerant is an amount that does not hinder the inflow of the vapor into the condensing tube when it is in a liquid state inside the evaporation unit and is as large as possible. The radiating fin is preferably made of a material having a high thermal conductivity, such as aluminum or copper.

  The heat radiating device according to the present invention may be configured to radiate heat from the radiating fin using forced convection by a fan or the like, or may be radiated from the radiating fin by natural convection. In the case of natural convection, it is preferable that the heat dissipating fins have a plate shape and the thickness, spacing, and area of the heat dissipating fins are appropriately designed so that heat is effectively radiated. Further, the heat dissipating device according to the present invention may be housed entirely inside the casing in order to cool a heating element such as an electronic device equipped inside the casing of a computer or the like. The heat dissipating fins may be mounted outside the housing.

  The heat dissipating device according to the present invention is provided so that the condensing tube can be arranged horizontally or inclined, and the condensing tube extends along the extending direction at a lower portion of the inner side surface when arranged horizontally or inclined. It is preferable to have a groove formed as described above. In this case, the refrigerant condensed and liquefied in the condenser tube can be smoothly returned to the evaporation section through the groove. For this reason, the circulation efficiency of a refrigerant | coolant can be improved and the cooling effect can be improved.

  The heat dissipating device according to the present invention has a connection pipe connected to the evaporation part on the opposite side of the evaporation surface so as to communicate with the inside of the evaporation part, and the condensation pipe intersects with the connection pipe. It may be provided and communicated with the inside of the evaporation section through the connection pipe. In this case, the condensing tube can be disposed away from the evaporation section, and the degree of freedom in arranging the heating element and the heat radiation position can be increased. For this reason, for example, the condenser tube and the heat radiating fins can be easily disposed outside the housing such as a computer, and the heat generated inside the housing can be released outside the housing. Thereby, a housing | casing can be sealed and intrusion of dust etc. can be prevented. In addition, it is preferable that not only the condensing tube but also a lower portion of the inner side surface of the connecting tube has a groove formed so as to extend along the extending direction.

  In the heat radiating device according to the present invention, the evaporation section is provided with a wick or a heat transfer promotion surface on an inner surface around the evaporation surface continuous to the evaporation surface, and a groove in the wick or the heat transfer promotion surface. It is preferable that the extending direction of is configured to be parallel to gravity during use. In this case, the refrigerant can be supplied from the periphery of the evaporation surface to the evaporation surface, and the effect of preventing the evaporation surface from drying and the evaporation efficiency of the refrigerant can be increased.

  According to the present invention, it is possible to provide a heat dissipating device that can secure an installation space easily and can effectively cool a CPU having a high heat generation density.

It is the (a) cross-sectional perspective view which shows the thermal radiation apparatus of the 1st Embodiment of this invention, (b) It is sectional drawing of a condensation pipe | tube. It is sectional drawing of the (a) top view which shows the thermal radiation apparatus of the 2nd Embodiment of this invention, (b) Sectional perspective view, (c) Sectional drawing of a condensation pipe | tube.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a heat dissipation device 10 according to a first embodiment of the present invention.
As shown in FIG. 1, the heat dissipation device 10 according to the first embodiment of the present invention includes an evaporation unit 11, a condenser tube 12, and a plurality of heat dissipation fins 13.

  As shown in FIG. 1A, the evaporation unit 11 has a rectangular parallelepiped box shape, and stores a liquid refrigerant 14 therein. The evaporation unit 11 has an inner surface composed of an evaporation surface 11a that is in thermal contact with the heating element 1 such as a CPU. The evaporation surface 11 a is provided so that the refrigerant 14 can be evaporated by the heat transmitted from the heating element 1. The evaporation unit 11 is provided with a wick or heat transfer promotion surface 11b on the evaporation surface 11a and four inner surfaces around the evaporation surface 11a continuous to the evaporation surface 11a. The refrigerant 14 is made of water, alcohol, or the like that can be evaporated and condensed within the operating temperature range.

  As shown in FIGS. 1A and 1B, the condensing tube 12 is rod-shaped, made of a material having high thermal conductivity, and has an annular cross-sectional shape. The condenser tube 12 is attached to the evaporation unit 11 at the center of the side surface opposite to the evaporation surface 11 a of the evaporation unit 11 so as to communicate with the inside of the evaporation unit 11. The condensation pipe 12 is provided with a heat transfer promotion surface 12a on the inner surface.

  As shown to Fig.1 (a), each radiation fin 13 consists of raw materials with large heat conductivity, such as aluminum and copper, and has comprised plate shape. Each radiating fin 13 is attached to the condensing tube 12 in parallel with each other at a predetermined interval along the length direction of the condensing tube 12 so as to extend outward from the outer surface of the condensing tube 12.

  As shown in FIG. 1A, in the heat dissipation device 10, the evaporation surface 11a is almost vertical along the heating element 1 arranged vertically, and the condenser tube 12 is inclined horizontally or downward toward the evaporation unit 11. It is attached to do. At this time, as shown in FIG. 1B, the heat dissipation device 10 has a groove 12 b formed in the lower part of the inner side surface of the condensing tube 12 so as to extend along the extending direction of the condensing tube 12. Moreover, as shown to Fig.1 (a), the thermal radiation apparatus 10 is comprised so that each thermal radiation fin 13 may be extended in an up-down direction. Further, when the heat transfer promotion surface is formed on the evaporation surface 11a and the inner side surface around the evaporation surface 11a, fine grooves on each heat transfer promotion surface arranged almost vertically so that the refrigerant 14 spreads upward by capillary force. The extension direction is provided so as to be parallel to the gravity. The refrigerant 14 is stored in a liquid state up to about half of the inside of the evaporation unit 11 (about the height of the inlet of the condensation tube 12) so as not to block the inlet from the evaporation unit 11 to the condensation tube 12. Yes.

  In the specific example shown in FIG. 1, each radiating fin 13 is made of copper and has a square plate shape of 40 mm × 40 mm. Each radiating fin 13 has a thickness of 0.5 mm, and a total of 88 pieces are installed along the condensation tube 12 at intervals of 1.2 mm. Thereby, the installation width of the radiation fin 13 is about 150 mm. When the amount of heat radiation at this time is calculated, it is about 170 W.

Next, the operation will be described.
As shown in FIG. 1 (a), the heat radiating device 10 has an evaporating surface 11 a of the evaporating section 11 having a heating element 1 for cooling a heating element 1 such as a CPU having a high heat generation density disposed on the base 2. Used to be in thermal contact with. In the heat dissipation device 10, the refrigerant 14 evaporates inside the evaporation unit 11 due to heat transmitted from the heating element 1 to the evaporation surface 11 a, and the vapor flows from the inside of the evaporation unit 11 toward the inside of the condensation tube 12. At this time, since the wick or the heat transfer promoting surface 11b is provided on the evaporation surface 11a, the boiling heat transfer resistance can be reduced and the refrigerant 14 can be easily evaporated. Even if the evaporation surface 11a stands vertically, the refrigerant 14 spreads along the evaporation surface 11a due to the capillary force generated on the wick or the heat transfer promotion surface 11b, so that the evaporation surface 11a is prevented from being dried and the refrigerant 14 is evaporated. Can be further promoted. Further, since the wick or the heat transfer promoting surface 11b is also provided on the inner side surface around the evaporation surface 11a, the refrigerant 14 can be supplied from the periphery of the evaporation surface 11a to the evaporation surface 11a by the capillary force. The effect of preventing the surface 11a from drying and the evaporation efficiency of the refrigerant 14 can be enhanced.

  When steam enters the condenser tube 12, the heat of the steam is released to the outside by the radiation fins 13, so that the steam is condensed and returned to the liquid refrigerant 14. At this time, as shown in FIG. 1 (b), the heat transfer promoting surface 12a is provided on the inner side surface of the condensing tube 12, so that the thermal resistance during condensation can be reduced and the vapor can be easily liquefied. it can. Thus, the heat dissipation device 10 can be evaporated and condensed with a high heat flux even with a low temperature difference, and can effectively cool the heating element 1 such as a CPU having a high heat generation density. Further, as shown in FIG. 1A, the heat radiating device 10 is arranged such that the condensing tube 12 is inclined horizontally or downwardly toward the evaporation unit 11, and a groove 12b is formed in the lower portion of the inner side surface of the condensing tube 12. Therefore, the condensed liquid refrigerant 14 can be smoothly returned to the evaporator 11 through the groove 12b, and the refrigerant 14 can be efficiently circulated to continuously cool the heating element 1.

  The heat dissipating device 10 can also be used in such a manner that the condenser tube 12 extends upward with the evaporation surface 11a facing downward when the orientation of an electronic device such as a CPU as the heating element 1 is horizontal. In this case, in order to make it easy to supply the refrigerant 14 to the evaporation surface 11a, a wick provided on the inner surface around the evaporation surface 11a or a minute groove of the heat transfer promotion surface 11b is formed along the direction of gravity. Is preferred.

  The orientation of electronic devices such as computer systems is mostly horizontal or vertical, but conventional thermosiphons can only handle horizontal ones. On the other hand, the heat radiating device 10 can cope with not only a horizontal heating element 1 such as an electronic device but also a vertical one, and can perform cooling regardless of the direction and arrangement of the heating element 1. it can. Moreover, since there is almost no restriction | limiting in arrangement | positioning of the evaporation part 11 and the condensation pipe | tube 12, compared with the conventional thermosiphon, it is easy to ensure installation space. For this reason, the heat radiating device 10 can be used, for example, in a rack-type large computer, a desktop type high-performance workstation, or the like.

  The heat radiating device 10 is housed in the housing and used for cooling the heating element 1 such as a CPU on the base 2 arranged almost vertically, which is mounted inside the housing of the computer. You can also In this case, heat can be radiated from the radiating fins 13 using forced convection by a fan or the like provided inside the housing.

FIG. 2 shows a heat dissipation device 20 according to a second embodiment of the present invention.
As shown in FIG. 2, the heat radiating device 20 according to the second embodiment of the present invention includes an evaporator 11, a connecting pipe 21, a condensing pipe 12, and a plurality of radiating fins 13. In the following description, the same reference numerals are given to the same components as those of the heat dissipation device 10 according to the first embodiment of the present invention, and duplicate descriptions are omitted.

  As shown in FIGS. 2 (a) to 2 (c), the connecting pipe 21 is rod-shaped and has an annular cross-sectional shape. The connecting pipe 21 is attached to the evaporation unit 11 at the center of the side surface opposite to the evaporation surface 11 a of the evaporation unit 11 so as to communicate with the inside of the evaporation unit 11. The condensing tube 12 is composed of one or a plurality of tubes, and is provided on the distal end side of the connecting tube 21 so as to be substantially orthogonal to the connecting tube 21. The condensing tube 12 is connected to the connecting tube 21 at the center thereof. The condensing pipe 12 communicates with the inside of the connecting pipe 21 and communicates with the inside of the evaporator 11 through the connecting pipe 21. In the specific example shown in FIG. 2, there are two condensing tubes 12, which are provided in parallel to each other.

  As shown in FIGS. 2A and 2B, in the heat dissipation device 20, the evaporation surface 11 a is substantially vertical along the heating element 1 arranged vertically, and the connection pipe 21 faces the horizontal or evaporation unit 11. The condensing tube 12 is attached so as to incline horizontally or downward toward the connecting tube 21. At this time, as shown in FIG. 2C, the heat dissipation device 20 has a groove (not shown) formed in the lower part of the inner side surface of the connection pipe 21 so as to extend along the extending direction of the connection pipe 21. doing. Moreover, it has the 1st groove | channel 12c formed in the lower part of the inner surface of the condensation pipe | tube 12 so that it might extend along the expansion | extension direction of the condensation pipe | tube 12. As shown in FIG.

  In addition, the heat radiating device 20 can be mounted so that the connecting pipe 21 extends upward along the heating element 1 arranged horizontally with the evaporation surface 11a facing downward. At this time, the heat radiating device 20 has a second groove 12 d formed at the lower portion of the inner side surface of the condensing tube 12 so as to extend along the extending direction of the condensing tube 12. In addition, even if the thermal radiation apparatus 20 is attached so that the evaporation surface 11a may become perpendicular | vertical, it is comprised so that each thermal radiation fin 13 may be extended in an up-down direction.

  In addition, as for the radiation fin 13, it is preferable that the fin pitch and fin thickness which are optimal are set on the conditions of forced convection or natural convection. Moreover, it is preferable that the radiation fin 13 is set to the magnitude | size from which the use condition, the thermal radiation amount, and fin efficiency become optimal, and the some condensation pipe | tube 12 is arrange | positioned according to it. In a specific example shown in FIG. 2, each radiating fin 13 is made of copper and has a square plate shape of 100 mm × 100 mm. Each radiating fin 13 has a thickness of 0.6 mm, and a total of 19 pieces are installed along the condensation tube 12 at intervals of 7.0 mm. Thereby, the installation width of the radiation fin 13 is about 150 mm. When the amount of heat release at this time is calculated, it is about 120 W.

Next, the operation will be described.
As shown in FIG. 2 (b), the heat radiating device 20 causes the evaporation surface 11a of the evaporation unit 11 to be in thermal contact with the heating element 1 such as a CPU attached to the inside of the housing 3 such as a computer to condense. The tube 12 and the heat radiating fin 13 can be used in a state where they are exposed to the outside of the housing 3. In the heat dissipation device 20, the heat transferred from the heating element 1 to the evaporation surface 11 a evaporates the refrigerant 14 inside the evaporation unit 11, and the vapor passes from the inside of the evaporation unit 11 through the connection pipe 21 to the inside of each condensation tube 12. It flows toward. When steam enters each condenser tube 12, the heat of the steam is released to the outside by the radiation fins 13, so that the steam is condensed and returned to the liquid refrigerant 14. At this time, if the evaporation surface 11a is attached so as to be vertical, the first groove 12c formed in the lower portion of the inner side surface of the condensing tube 12 and the groove formed in the lower portion of the inner side surface of the connecting tube 21 are passed through. The condensed liquid refrigerant 14 can be smoothly returned to the evaporation section 11. Further, if the evaporation surface 11a is mounted so as to be horizontal, the condensed liquid refrigerant 14 is evaporated via the connection tube 21 through the second groove 12d formed in the lower portion of the inner surface of the condensation tube 12. The part 11 can be returned smoothly. Thus, the heat radiating device 20 can efficiently cool the heating element 1 by circulating the refrigerant 14 efficiently.

  The heat radiating device 20 can release heat generated inside the housing 3 to the outside of the housing 3. Accordingly, since the CPU or the like can be cooled without introducing outside air into the housing 3, the housing 3 can be sealed, and dust such as dust, dust, and fine particles is collected by the housing 3. Can be prevented from entering the inside. Thereby, failure of a computer etc. can be prevented and the improvement of apparatus reliability can be expected. Further, it is not necessary to provide a cooling fan inside the housing 3, and noise can be reduced.

  Since the heat radiating device 20 can arrange | position the condensation pipe | tube 12 away from the evaporation part 11, it can raise the freedom degree of arrangement | positioning of the heat generating body 1 and a thermal radiation position. The heat radiating device 20 may perform heat radiation using forced convection by a fan or the like installed outside the housing 3, not natural convection.

DESCRIPTION OF SYMBOLS 1 Heat generating body 2 Base 3 Case 10, 20 Heat radiating device 11 Evaporating part 11a Evaporating surface 11b Wick or heat transfer promoting surface 12 Condensation tube 12a Heat transfer promoting surface 12b Groove 12c First groove 12d Second groove 13 Radiation fin 14 Refrigerant 21 Connection pipe

Claims (6)

An evaporation section for storing a liquid refrigerant inside;
A condenser pipe provided to communicate with the inside of the evaporation section;
A plurality of heat dissipating fins provided to extend outward from the outer surface of the condensing tube;
The evaporation unit has an evaporation surface provided on an inner surface in thermal contact with the heating element so that the refrigerant can be evaporated by heat transmitted from the heating element, and the evaporation surface has a wick or heat transfer promotion. Surface is provided,
The heat radiating device is characterized in that the condensation pipe is provided with a heat transfer promotion surface on an inner surface, and communicates with the inside of the evaporation section on the opposite side of the evaporation surface. The condensing pipe is provided so as to be horizontally or inclined,
The heat radiating device according to claim 1, wherein the condensing tube has a groove formed to extend along an extending direction at a lower portion of an inner surface when the condensing tube is disposed horizontally or inclined. A connecting pipe connected to the evaporation part on the opposite side of the evaporation surface so as to communicate with the inside of the evaporation part;
The heat radiating device according to claim 1, wherein the condensing pipe is provided so as to intersect the connecting pipe and communicates with the inside of the evaporator through the connecting pipe.   The wick provided on the evaporation surface or the groove extending direction of the heat transfer promoting surface is provided so as to be parallel to gravity when in use. The heat radiating device described in 1. The radiating fin has a plate shape,
The heat dissipating device according to claim 1, wherein the heat dissipating fins are arranged so as to extend in a vertical direction. The evaporating part is provided with a wick or a heat transfer promoting surface on the inner side surface around the evaporation surface which is continuous with the evaporation surface, and the extending direction of the groove of the wick or the heat transfer promoting surface is in use, The heat dissipation device according to any one of claims 1 to 5, wherein the heat dissipation device is configured to be parallel to gravity.