Heat pipe

Abstract

The present invention provides a heat pipe that has excellent circulation properties for a working fluid, that makes it possible to prevent abnormal noise from occurring during circulation of the working fluid, and that demonstrates excellent heat transport properties.　This heat pipe is provided with: a container which is a tube and has a sealed end surface at one end and the other end; a wick structure provided to the interior of the container; and a working fluid sealed in the interior of the container. In at least one cross-section of the cross-sections of the direction orthogonal to the longitudinal direction of the container, the wick structure includes: a first wick part having a thickness of 50% or more of the height of an interior space of the container; and a second wick part that is integrated with the first wick part, stretches to an outer direction from the first wick part, and has a thickness of less than 50% of the height of the interior space of the container, the second wick part having a flat section that extends along a direction orthogonal to the height direction of the interior space of the container.

Description

Technical Field

[0001] The present invention relates to a heat pipe that has excellent flow characteristics of a working fluid, exhibits excellent heat transport characteristics, and can prevent the generation of abnormal noise during the flow of the working fluid.

Background Art

[0002] Electronic components such as semiconductor elements mounted on electric and electronic devices such as notebook computers and servers have an increasing heat generation amount due to high functionality and the like, and their cooling has become even more important. As a cooling means for electronic components, a heat pipe may be used. Further, due to the miniaturization of electric and electronic devices, the internal space of electric and electronic devices is becoming increasingly narrow, and thus the heat pipe is also required to be further miniaturized. Therefore, a thin heat pipe with a flattened container may be used.

[0003] Also, a flattened thin heat pipe may be required to reliably maintain an internal space that has been subjected to a pressure reduction process in order to secure a flow path for the working fluid. Therefore, at least one stick having a height that prevents the collapse of the container body is fixed in the longitudinal direction at the center inside the flat container body, and a wick for working fluid reflux is integrally laid at the inner half of the container body with a thickness lower than the height of the stick. A heat pipe has been proposed (Patent Document 1). In Patent Document 1, the collapse of the container is prevented by standing a stick inside the flattened container, and a flow path for the working fluid is secured.

[0004] However, in Patent Document 1, a stay, which is a different component from the wick structure, is provided in the internal space of the heat pipe, which reduces the amount of wick structure that can be installed and also reduces the steam passage through which the gaseous working fluid flows. Furthermore, in Patent Document 1, the wick structure extends across the entire width direction of the flat container, which also reduces the steam passage. Therefore, Patent Document 1 had the problem that the working fluid flow characteristics could not be obtained sufficiently. Moreover, in Patent Document 1, because the working fluid flow characteristics could not be obtained sufficiently, the maximum heat transport capacity could not be obtained sufficiently, and excellent heat transport characteristics could not be exhibited.

[0005] Furthermore, as described in Patent Document 1, if the flow characteristics of the working fluid are not sufficiently obtained, the liquid phase working fluid may accumulate in the vapor passage of the heat pipe's condensation section. Also, if a wick structure is provided only in the center of the container in the width direction in order to secure the vapor passage, the liquid phase working fluid may accumulate in the vapor passage at the width direction end of the heat pipe's condensation section. In particular, if the heat pipe's condensation section is located downward in the direction of gravity, the liquid phase working fluid is more likely to accumulate in the vapor passage of the heat pipe's condensation section.

[0006] For example, if the liquid phase working fluid is stored in the vapor channel of the condenser located downward in the direction of gravity, and the orientation of an electrical / electronic device such as a laptop computer is changed, causing the condenser to move upward in the direction of gravity, the liquid phase working fluid stored in the condenser will flow downward in the direction of gravity. When the liquid phase working fluid flows downward in the direction of gravity, it can collide with the gaseous phase working fluid flowing through the vapor channel from the evaporation section of the heat pipe to the condenser located upward in the direction of gravity. This can cause the liquid phase working fluid to be blown away by the gaseous phase working fluid, resulting in the generation of abnormal noise.

[0007] Furthermore, the liquid working fluid stored in the vapor channel of the condensation section flowed downward in the direction of gravity and collided with the gaseous working fluid, causing a pressure loss in the flow of the gaseous working fluid. As a result, it was unable to exhibit excellent heat transport characteristics. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2002-213887 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In view of the above circumstances, the present invention aims to provide a heat pipe that has excellent fluid flow characteristics and excellent heat transport characteristics, while preventing the generation of abnormal noise during the flow of the working fluid. [Means for solving the problem]

[0010] The gist of the present invention is as follows: [1] A container which is a tube, with the end face of one end sealed to the end face of the other end, and a wick structure provided inside the container, The working fluid sealed inside the container, A heat pipe equipped with, In at least one cross-section of the container perpendicular to its longitudinal direction, the wick structure comprises a first wick portion and a second wick portion that is integral with the first wick portion, extends outward from the first wick portion, and is thinner than the first wick portion. The second wick portion is a heat pipe having a flat portion that extends along a direction perpendicular to the height direction of the internal space of the container. [2] The heat pipe according to [1], wherein the first wick portion has a thickness of 50% or more of the height of the internal space of the container, and the second wick portion has a thickness of less than 50% of the height of the internal space of the container. [3] The heat pipe according to [1] or [2], wherein at least a portion of the container has a flattened portion. [4] The heat pipe according to [3], wherein the flattened portion has one inner surface and another inner surface opposite to the first inner surface in the height direction of the internal space of the container, and in one cross-section, the first wick portion has a top portion in contact with the first inner surface and a bottom portion in contact with the other inner surface. [5] The heat pipe according to any one of [1] to [4], wherein in one cross-section, the wick structure has a gradually decreasing portion between the top of the first wick portion and the flat portion, along a direction perpendicular to the height direction of the internal space of the container, in which the thickness of the wick structure decreases continuously. [6] The heat pipe according to any one of [1] to [5], wherein in one cross-section, the ratio of the width of the second wick to the sum of the width of the second wick and the width from the tip of the second wick to the inner surface of the container facing the tip of the second wick is 50% or more. [7] The heat pipe according to any one of [1] to [6], wherein the tip of the second wick portion is not in contact with the inner surface of the container opposite to the tip of the second wick portion. [8] The heat pipe according to any one of [1] to [7], wherein in one cross-section, the ratio of the cross-sectional area of ​​the second wick portion to the cross-sectional area of ​​the first wick portion is 1.0% or more and 50% or less. [9] The heat pipe according to any one of [1] to [8], wherein the container has an evaporation section thermally connected to a heating element and a condensation section thermally connected to a heat exchange means, and the thickness of the flat section in the evaporation section is greater than the thickness of the flat section in the condensation section.

[10] The heat pipe according to any one of [1] to [9], wherein in one cross-section, the ratio of the cross-sectional area of ​​the internal space of the container not occupied by the wick structure to the cross-sectional area of ​​the wick structure is 15% or more and 65% or less.

[11] The heat pipe according to any one of [1] to

[10] , wherein the wick structure is a sintered body of metal powder.

[0011] In the above embodiment, the "flat portion" of the second wick means a portion where the rate of change in the thickness of the second wick is 5.0% or less of the height of the container's interior space, in a direction perpendicular to the height direction of the container's interior space (hereinafter sometimes referred to as the "width direction of the container's interior space"). Furthermore, in the above embodiment, the "gradually changing portion" of the wick structure means a portion where, in the width direction of the container's interior space, the rate of change in the thickness of the wick structure with respect to a unit length in the width direction of the container's interior space exceeds 5.0% of the height of the container's interior space. [Effects of the Invention]

[0012] According to an embodiment of the heat pipe of the present invention, the wick structure has a first wick portion and a second wick portion that is thinner than the first wick portion, that is, the first wick portion is relatively thick in the height direction of the internal space of the container, thereby having excellent reflux characteristics from the condensation portion to the evaporation portion of the liquid phase working fluid. Furthermore, according to an embodiment of the heat pipe of the present invention, the second wick portion, which is relatively thin in the height direction of the internal space of the container and extends outward from the first wick portion, has a flat portion that extends along the width direction of the internal space of the container, thereby ensuring a sufficient vapor passage for the flow of the gas phase working fluid, while the liquid phase working fluid is absorbed into the wick structure by the capillary force of the flat portion. Therefore, by having a flat portion in the second wick portion, it is possible to prevent the accumulation of the liquid phase working fluid at the width direction end of the condensation portion of the heat pipe within the internal space of the container. As described above, according to the embodiment of the heat pipe of the present invention, the heat pipe has excellent flow characteristics for the working fluid and exhibits excellent heat transport characteristics, while preventing the generation of abnormal noise during the flow of the working fluid even when the installation orientation of the electrical and electronic equipment equipped with the heat pipe of the present invention is changed. Furthermore, according to the embodiment of the heat pipe of the present invention, the wick structure has a first wick section having a thickness of 50% or more of the height of the internal space of the container, thereby having even better reflux characteristics from the condensation section to the evaporation section of the liquid phase working fluid. Moreover, according to the embodiment of the heat pipe of the present invention, the second wick section, which has a thickness of less than 50% of the height of the internal space of the container and extends outward from the first wick section having a thickness of 50% or more of the height of the internal space of the container, has a flat section that extends along the width direction of the internal space of the container, thereby further securing a sufficient vapor passage for the flow of the gas phase working fluid, while the liquid phase working fluid is absorbed into the wick structure by the capillary force of the flat section. Therefore, by having a flat section in the second wick section, which has a thickness of less than 50% of the height of the container's internal space, it is possible to prevent the accumulation of liquid-phase working fluid at the widthwise end of the heat pipe's condensation section within the container's internal space.As described above, according to the embodiment of the heat pipe of the present invention, while having even better flow characteristics for the working fluid and exhibiting even better heat transport characteristics, it is possible to prevent the generation of abnormal noise during the flow of the working fluid even when the installation orientation of the electrical and electronic equipment equipped with the heat pipe of the present invention is changed.

[0013] According to an embodiment of the heat pipe of the present invention, the first wick portion has a top portion in contact with one inner surface of the container and a bottom portion in contact with the other inner surface of the container, thereby reliably improving the reflux characteristics of the liquid phase working fluid from the condensation portion to the evaporation portion.

[0014] According to an embodiment of the heat pipe of the present invention, the ratio of the width of the second wick portion to the sum of the width of the second wick portion and the width from the tip of the second wick portion to the inner surface of the container facing the tip of the second wick portion is 50% or more, thereby making it possible to more reliably prevent the accumulation of liquid-phase working fluid at the widthwise end of the internal space of the container.

[0015] According to an embodiment of the heat pipe of the present invention, since the tip of the second wick portion does not come into contact with the inner surface of the container facing the tip of the second wick portion, the steam flow path is more reliably secured, and the flow characteristics of the gaseous working fluid are further improved.

[0016] According to an embodiment of the heat pipe of the present invention, by setting the ratio of the cross-sectional area of ​​the second wick to the cross-sectional area of ​​the first wick to 1.0% or more and 50% or less, it is possible to balance and improve the excellent flow characteristics of the working fluid with the prevention of abnormal noise during the flow of the working fluid.

[0017] According to an embodiment of the heat pipe of the present invention, the thickness of the flat portion of the second wick in the evaporation section is greater than the thickness of the flat portion in the condensing section, thereby improving the capillary force of the second wick in the evaporation section, and thus improving the reflux characteristics of the liquid phase working fluid from the condensing section to the evaporation section.

[0018] According to the aspect of the heat pipe of the present invention, by setting the ratio of the cross-sectional area of the internal space of the container not occupied by the wick structure to the cross-sectional area of the wick structure to be 10% or more and 50% or less, the flow characteristics of the liquid-phase working fluid and the flow characteristics of the gas-phase working fluid can be improved in a well-balanced manner.

Brief Description of Drawings

[0019] [Figure 1] It is an explanatory diagram showing an outline of a cross-section in the longitudinal direction of a heat pipe according to a first embodiment of the present invention. [Figure 2] It is an explanatory diagram showing an outline of a cross-section in a direction orthogonal to the longitudinal direction of a heat pipe according to a first embodiment of the present invention. [Figure 3] It is an explanatory diagram showing an outline of a cross-section in the longitudinal direction of a heat pipe according to a second embodiment of the present invention. [Figure 4] It is an explanatory diagram showing an outline of a cross-section in the longitudinal direction of a heat pipe according to a third embodiment of the present invention. [Figure 5] It is an explanatory diagram showing an outline of a cross-section in the longitudinal direction of a heat pipe according to a fourth embodiment of the present invention.

[0020] Hereinafter, the heat pipe according to the first embodiment of the present invention will be described with reference to the drawings. Note that FIG. 1 is an explanatory diagram showing an outline of a cross-section in the longitudinal direction of the heat pipe according to the first embodiment of the present invention. FIG. 2 is an explanatory diagram showing an outline of a cross-section in a direction orthogonal to the longitudinal direction of the heat pipe according to the first embodiment of the present invention.

[0021] As shown in Figure 1, the heat pipe 1 according to the first embodiment of the present invention comprises a container 10 which is a tubular body with one end face 12 of one end 11 and the other end face and 14 of the other end 13 sealed, a wick structure 20 provided inside the container 10, and a working fluid (not shown) sealed inside the container 10. The shape of the container 10 is elongated. The longitudinal shape of the container 10 can be appropriately selected depending on the usage situation, and may be straight or have a curved shape, but for the sake of explanation, the heat pipe 1 is straight. The inside of the container 10 is a sealed space that has been subjected to a reduced pressure treatment.

[0022] The wick structure 20 extends along the longitudinal direction of the container 10, from one end 11 to the other end 13. The width of the wick structure 20 is approximately the same along the longitudinal direction of the container 10. The heat pipe 1 functions as an evaporation section, for example, when a heating element 100 is thermally connected to one end 11, and as a condensation section when a heat exchange means (not shown) is thermally connected to the other end 13. From the above, the wick structure 20 extends along the heat transport direction of the heat pipe 1.

[0023] The cross-sectional shape of the container 10 in the direction perpendicular to the longitudinal direction is not particularly limited, but as shown in Figure 2, the heat pipe 1 has a flattened shape. Therefore, the heat pipe 1 is a thin heat pipe having a flattened portion. The wall thickness of the container 10 is not particularly limited, but for example, it is 0.1 mm to 0.5 mm. The height H of the internal space 15 of the container 10 is not particularly limited, but for example, it is 0.5 mm to 2.0 mm. The dimension in the direction perpendicular to the height H of the internal space 15 of the container 10 (i.e., the width direction W of the internal space 15 of the container 10) is not particularly limited, but for example, it is 5 mm to 30 mm.

[0024] As shown in Figure 2, in a cross-section perpendicular to the longitudinal direction of the container 10, the wick structure 20 has a first wick portion 21 having a predetermined thickness and a second wick portion 22 that is thinner than the first wick portion 21. Therefore, in the above cross-section, the first wick portion 21 is thicker than the second wick portion 22. The wick structure 20 only needs to have a first wick portion 21 which is a relatively thick part and a second wick portion 22 which is a relatively thin part in the above cross-section, but in the heat pipe 1, in a cross-section perpendicular to the longitudinal direction of the container 10, the wick structure 20 has a first wick portion 21 which has a thickness of 50% or more of the height H of the internal space 15 of the container 10 and a second wick portion 22 which has a thickness of less than 50% of the height H of the internal space 15 of the container 10. The second wick portion 22 is integral with the first wick portion 21 and extends outward from the first wick portion 21. In the heat pipe 1, a first wick portion 21 is provided in the center of the width direction W of the internal space 15 of the container 10, and second wick portions 22 are provided continuously on both sides of the first wick portion 21. The second wick portions 22 are provided near both ends of the width direction W of the internal space 15 of the container 10.

[0025] The flattened portion of the container 10 has one inner surface 16 and the other inner surface 17 facing the first inner surface 16, in the direction of the height H of the internal space 15 of the container 10. The first wick portion 21 has a top portion 23 that is in contact with the one inner surface 16 and a bottom portion 24 that is in contact with the other inner surface 17. Therefore, in the heat pipe 1, the first wick portion 21 has a portion with a thickness corresponding to the height H of the internal space 15 of the container 10, that is, a portion with a thickness of 100% of the height H of the internal space 15 of the container 10. From the above, the thickness of the portion of the first wick portion 21 corresponding to the top portion 23 maintains a thickness corresponding to the height H of the internal space 15. In the heat pipe 1, the top portion 23 of the first wick portion 21 is in surface contact with the one inner surface 16, and the bottom portion 24 of the first wick portion 21 is in surface contact with the other inner surface 17.

[0026] The second wick portion 22 is provided in contact with the other inner surface 17, and is not in contact with the one inner surface 16 or the inner surface 18 connecting the one inner surface 16 and the other inner surface 17. Therefore, the second wick portion 22 is not provided on the one inner surface 16 or the inner surface 18. The portion of the one inner surface 16 that is not in contact with the first wick portion 21 and the inner surface 18 are both exposed to the internal space 15.

[0027] The second wick portion 22 has a flat portion 30 that extends along the width direction W of the internal space 15 of the container 10. The flat portion 30 is formed at both ends of the second wick portion 22 in the width direction W of the internal space 15. The flat portion 30 extends over a predetermined length from the first wick portion 21 toward the inner surface 18 while maintaining a predetermined thickness of less than 50% of the height H of the internal space 15. Although the flat portion 30 maintains a predetermined thickness of less than 50% of the height H of the internal space 15, it is preferable to maintain a predetermined thickness of less than 30% of the height H of the internal space 15, and particularly preferable to maintain a predetermined thickness of less than 20% of the height H of the internal space 15, in order to further sufficiently secure a steam passage 50 through which the gas phase working fluid flows while reliably preventing the accumulation of the liquid phase working fluid. On the other hand, the flat portion 30 preferably maintains a predetermined thickness of 10% or more of the height H of the internal space 15, in order to more reliably prevent the accumulation of liquid-phase working fluid at the widthwise end W of the internal space 15 of the container 10. Since the flat portion 30 extends from the first wick portion 21 toward the inner surface 18 while maintaining the predetermined thickness, it has a substantially flat shape.

[0028] In the above cross-section, the ratio of the width W1 of the second wick portion 22 to the sum of the width W1 of the second wick portion 22 and the width W2 from the tip 31 of the second wick portion 22 to the inner surface of the container 10 facing the tip 31 of the second wick portion 22 (in Figure 2, the inner surface 18 of the container 10) is not particularly limited, but in the heat pipe 1, it is 50% or more. On the other hand, in the heat pipe 1, the tip 31 of the second wick portion 22 does not come into contact with the inner surface 18 of the container 10. Therefore, the ratio of the width W1 of the second wick portion 22 to the sum of the width W1 of the second wick portion 22 and the width W2 from the tip 31 of the second wick portion 22 to the inner surface 18 facing the tip 31 is less than 100%.

[0029] Thus, since the tip 31 of the second wick portion 22 is not in contact with the inner surface 18 of the container 10, the second wick portion 22, including the flat portion 30, does not extend to the inner surface 18 of the container 10, and the tip 31 of the second wick portion 22 faces the inner surface 18 at a predetermined distance. Therefore, the other inner surface 17 has a portion that is not in contact with either the first wick portion 21 or the second wick portion 22, and this portion is exposed to the internal space 15.

[0030] The thickness of the flat portion 30 may be approximately the same along the longitudinal direction of the container 10, or it may be different in thickness depending on the longitudinal part of the container 10. When the thickness of the flat portion 30 is different in thickness depending on the longitudinal part of the container 10, it is preferable that the thickness of the flat portion 30 in the evaporation section where the container 10 is thermally connected to the heating element 100 is greater than the thickness of the flat portion 30 in the condensation section where the container 10 is thermally connected to a heat exchange means (not shown), as this improves the capillary force of the second wick portion 22 in the evaporation section and further improves the reflux characteristics of the liquid phase working fluid from the condensation section to the evaporation section.

[0031] As shown in Figure 2, the wick structure 20 has a gradually changing section 40 between the top 23 of the first wick section 21 and the flat section 30, where the thickness of the wick structure 20 continuously decreases along the width direction W of the internal space 15 of the container 10. The gradually changing section 40 is formed spanning the first wick section 21 and the second wick section 22, and the thickness of the wick structure 20 decreases as you move from the first wick section 21 to the second wick section 22. In the width direction W of the internal space 15 of the container 10, the rate of change in the thickness of the wick structure 20 in the gradually changing section 40 is greater than the rate of change in the thickness of the wick structure 20 in the flat section 30.

[0032] In the above cross-section, the ratio of the cross-sectional area of ​​the second wick portion 22 to the cross-sectional area of ​​the first wick portion 21 is not particularly limited, but in the heat pipe 1, in order to ensure sufficient space for the vapor passage 50 through which the gaseous working fluid flows while reliably preventing the accumulation of the liquid working fluid, a ratio of 1.0% to 50% is preferred, and a ratio of 10% to 30% is particularly preferred.

[0033] Of the internal space 15 of the container 10, the internal space 15 not occupied by the wick structure 20 is a steam passage 50 through which the gaseous working fluid flows. Corresponding to the fact that the wick structure 20 extends along the heat transport direction of the heat pipe 1, the steam passage 50 extends along the heat transport direction of the heat pipe 1.

[0034] In the above cross-section, the ratio of the cross-sectional area of ​​the internal space 15 (steam flow path 50) of the container 10 not occupied by the wick structure 20 to the cross-sectional area of ​​the wick structure 20 is not particularly limited, but in the heat pipe 1, it is preferable that it is between 15% and 65%, and particularly preferable that it is between 20% and 60%, in order to improve the flow characteristics of the liquid phase working fluid and the gas phase working fluid in a balanced manner. More specifically, in the heat pipe 1, the ratio of the cross-sectional area of ​​the internal space 15 of the container 10 not occupied by the wick structure 20 to the cross-sectional area of ​​the wick structure 20 is between 30% and 50%.

[0035] The material of the container 10 is not particularly limited. For example, copper and copper alloys can be used due to their excellent thermal conductivity, aluminum and aluminum alloys due to their light weight, and stainless steel due to its improved mechanical strength. Depending on the usage of the heat pipe 1, tin, tin alloys, titanium, titanium alloys, nickel, and nickel alloys may also be used.

[0036] Examples of wick structures include sintered bodies of powders containing metal powder. Specific examples include sintered bodies of metal powders such as copper powder and stainless steel powder, and sintered bodies of mixed powders of copper powder and carbon powder. The first wick section 21 and the second wick section 22 may be made of the same material type or different material types. Furthermore, the average particle sizes of the powders in the first wick section 21 and the second wick section 22 may be the same or different. The average primary particle size of the metal powder used as the raw material for the sintered body can be appropriately selected based on the capillary force required for the wick structure 20 and the reflux characteristics of the liquid phase working fluid, for example, between 50 μm and 100 μm.

[0037] Furthermore, the working fluid sealed in the container 10 can be appropriately selected depending on the material of the container 10, and examples include water, alternative fluorocarbons, perfluorocarbons, cyclopentane, etc.

[0038] Next, an example of a heat pipe manufacturing method of the present invention will be described. The manufacturing method of the heat pipe of the present invention is not particularly limited, but for example, if the wick structure 20 is a sintered body of powder, it can be manufactured by using a core rod provided with a notch of a predetermined shape for filling with the powder that will be the raw material for the wick structure 20. Specifically, for example, a core rod of the above shape is inserted from one end to the other in the longitudinal direction of a circular pipe. A void is formed between the inner wall surface of the pipe and the outer surface of the core rod based on the notch. A predetermined amount of powder, which is the raw material for the wick structure 20, is filled into the void from the end of the pipe. The pipe filled with powder is heat-treated, the core rod is pulled out of the pipe, and the pipe is flattened. When the pipe is flattened, the wick structure 20 is formed from the powder that was filled into the notch.

[0039] Next, the heat transport mechanism of the heat pipe 1 according to the first embodiment of the present invention will be described. In the heat pipe 1, for example, by thermally connecting a heating element 100 to one end 11, one end 11 functions as an evaporation section (heat receiving section), and by thermally connecting a heat exchange means to the other end 13, the other end 13 functions as a condensation section (heat dissipation section). In addition, the central section 19 located between one end 11 and the other end 13 functions as an insulating section. When heat is received from the heating element 100 in the evaporation section of the heat pipe 1, the working fluid undergoes a phase change from liquid phase to gas phase. The working fluid, which has undergone a phase change to the gas phase, flows through the steam flow path 50 in the longitudinal direction of the container 10 from the evaporation section to the condensation section (in the heat pipe 1, from one end 11 to the other end 13), thereby transporting heat from the heating element 100 from the evaporation section to the condensation section. The heat from the heat-generating element 100, transported from the evaporation section to the condensation section, is released as latent heat in the condensation section, where a heat exchange means is provided, as the gaseous working fluid undergoes a phase change to a liquid phase. The latent heat released in the condensation section is then released from the condensation section to the external environment of the heat pipe 1 by the heat exchange means provided in the condensation section. The working fluid, which has undergone a phase change to a liquid phase in the condensation section, is recirculated from the condensation section to the adiabatic section by the capillary force of the wick structure 20.

[0040] In the heat pipe 1 according to the first embodiment of the present invention, the wick structure 20 has a first wick portion 21 having a thickness of 50% or more of the height H of the internal space 15 of the container 10, thereby providing excellent reflux characteristics from the condensation portion to the evaporation portion of the liquid-phase working fluid. Furthermore, the second wick portion 22, which extends outward from the first wick portion 21 and has a thickness of less than 50% of the height H of the internal space 15 of the container 10, has a flat portion 30 that extends along the width direction W of the internal space 15 of the container 10. This ensures a sufficient vapor passage 50 through which the gas-phase working fluid flows, and the capillary force of the flat portion 30 absorbs the liquid-phase working fluid stored at the width direction W end of the internal space 15 of the container 10 into the wick structure 20. Therefore, the presence of the flat portion 30 in the second wick portion 22 prevents the storage of liquid-phase working fluid at the width direction W end of the internal space 15 of the container 10, which is part of the condensation portion of the heat pipe 1. From the above, the heat pipe 1 has excellent fluid flow characteristics and exhibits excellent heat transport characteristics, and can prevent the generation of abnormal noise during fluid flow even when the installation orientation of the electrical / electronic equipment on which the heat pipe 1 is mounted is changed.

[0041] Furthermore, since the second wick section 22 has a flat section 30 that extends along the width direction W of the internal space 15 of the container 10, the evaporation area of ​​the working fluid in the evaporation section is increased, thereby reducing the thermal resistance. In addition, the heat pipe 1 prevents the accumulation of liquid-phase working fluid in the condensation section of the heat pipe 1, so that the heat pipe 1 can reliably contribute to heat transport from one end 11 to the other end 13 of the container 10.

[0042] Furthermore, in the heat pipe 1, the portion of one inner surface 16 that is not in contact with the first wick portion 21 and the inner surface 18 do not have a wick structure formed on them and are exposed to the internal space 15, so that a sufficient steam flow path 50 is secured and the gaseous working fluid can flow smoothly.

[0043] Furthermore, in the heat pipe 1, the first wick portion 21 has a top portion 23 that is in contact with one inner surface 16 of the container 10 and a bottom portion 24 that is in contact with the other inner surface 17. In other words, the first wick portion 21 has a portion that has a thickness of 100% of the height H of the internal space 15 of the container 10, so it has excellent reflux characteristics from the condensation portion to the evaporation portion of the liquid phase working fluid.

[0044] In the heat pipe 1, the ratio of the width W1 of the second wick portion 22 to the sum of the width W1 of the second wick portion 22 and the width W2 from the tip 31 of the second wick portion 22 to the inner surface 18 facing the tip 31 is 50% or more, thereby more reliably preventing the accumulation of liquid-phase working fluid at the widthwise end W of the internal space 15 of the container 10.

[0045] In the heat pipe 1, the tip 31 of the second wick portion 22 is not in contact with the inner surface 18 of the container facing the tip 31 of the second wick portion 22, so the steam flow path 50 is more reliably secured, and the flow characteristics of the gaseous working fluid are further improved.

[0046] In the heat pipe 1, the ratio of the cross-sectional area of ​​the second wick section 22 to the cross-sectional area of ​​the first wick section 21 is between 1.0% and 50%, thus achieving a good balance between excellent fluid flow characteristics and prevention of abnormal noise during fluid flow.

[0047] Next, a second embodiment of the heat pipe of the present invention will be described. Note that the heat pipe according to the second embodiment shares the same main components as the heat pipe according to the first embodiment, and therefore the same components will be described using the same reference numerals. Figure 3 is an explanatory diagram showing an overview of the longitudinal cross-section of the heat pipe according to the second embodiment of the present invention.

[0048] In the heat pipe 1 according to the first embodiment, the longitudinal shape of the container 10 was straight. However, as shown in Figure 3, in the heat pipe 2 according to the second embodiment, the longitudinal shape of the container 10 has a curved portion 51. Specifically, in the heat pipe 2, the container 10 is L-shaped with one curved portion 51.

[0049] Even with a heat pipe 2 in which the container 10 is L-shaped, it is possible to prevent the accumulation of liquid-phase working fluid in the condensation portion of the heat pipe 2, specifically at the widthwise end of the internal space 15 of the container 10. As a result, even with a heat pipe 2, the working fluid has excellent flow characteristics and exhibits excellent heat transport characteristics, while preventing the generation of abnormal noise during the flow of the working fluid even when the installation orientation of the electrical and electronic equipment on which the heat pipe 2 is mounted is changed.

[0050] Next, a third embodiment of the heat pipe of the present invention will be described. Note that the heat pipe according to the third embodiment shares the same main components as the heat pipes according to the first and second embodiments, so the same components will be described using the same reference numerals. Figure 4 is an explanatory diagram showing an overview of the longitudinal cross-section of the heat pipe according to the third embodiment of the present invention.

[0051] In the heat pipe 1 according to the first embodiment, the longitudinal shape of the container 10 was linear. However, as shown in Figure 4, in the heat pipe 3 according to the third embodiment, the longitudinal shape of the container 10 has multiple curved sections 51 (two in the case of heat pipe 3).

[0052] Even in a heat pipe 3 where the container 10 has a shape with two curved sections 51, it is possible to prevent the accumulation of liquid-phase working fluid in the condensation section of the heat pipe 3, specifically at the widthwise end of the internal space 15 of the container 10. As described above, even with a heat pipe 3, the working fluid has excellent flow characteristics and exhibits excellent heat transport characteristics, while preventing the generation of abnormal noise during the flow of the working fluid even when the installation orientation of the electrical and electronic equipment on which the heat pipe 3 is mounted is changed.

[0053] Next, a fourth embodiment of the heat pipe of the present invention will be described. Note that the heat pipe according to the fourth embodiment shares the same main components as the heat pipes according to the first to third embodiments, and therefore the same components will be described using the same reference numerals. Figure 5 is an explanatory diagram showing an overview of the longitudinal cross-section of the heat pipe according to the fourth embodiment of the present invention.

[0054] In the heat pipe 1 according to the first embodiment, the longitudinal shape of the container 10 was linear. However, as shown in Figure 5, in the heat pipe 4 according to the fourth embodiment, the longitudinal shape of the container 10 has multiple curved sections 51 (four in the case of heat pipe 4). Furthermore, in the heat pipe 1 according to the first embodiment, the heating element 100 was thermally connected to one end 11 of the container 10. However, as shown in Figure 5, in the heat pipe 4 according to the fourth embodiment, the heating element 100 is thermally connected to the central part 19 of the container 10, and the central part 19 of the container 10 functions as an evaporation section (heat receiving section). Therefore, in the heat pipe 4, one end 11 and the other end 13 of the container 10 function as a condensation section (heat dissipation section).

[0055] The container 10 has a shape with four curved sections 51, and even in a heat pipe 4 to which the heating element 100 is thermally connected to the central part 19 of the container 10, it is possible to prevent the accumulation of liquid-phase working fluid in the condensation section of the heat pipe 4, specifically at the widthwise end of the internal space 15 of the container 10. As a result, even with the heat pipe 4, the working fluid has excellent flow characteristics and exhibits excellent heat transport characteristics, and even when the installation orientation of the electrical and electronic equipment on which the heat pipe 4 is mounted is changed, it is possible to prevent the generation of abnormal noise during the flow of the working fluid.

[0056] Next, other embodiments of the heat pipe of the present invention will be described. In each of the above embodiments of the heat pipe, in a cross-section perpendicular to the longitudinal direction of the container 10, the wick structure 20 had a first wick portion 21 having a thickness of 50% or more of the height H of the internal space 15 of the container 10 and a second wick portion 22 having a thickness of less than 50% of the height H of the internal space 15 of the container 10. However, in the above cross-section, if the first wick portion 21 is thicker than the second wick portion 22 (the second wick portion 22 is thinner than the first wick portion 21), the thickness of the first wick portion 21 and the second wick portion 22 with respect to the height H of the internal space 15 is not particularly limited. Furthermore, in the above embodiments of the heat pipe, the ratio of the width W1 of the second wick portion 22 to the sum of the width W1 of the second wick portion 22 and the width W2 from the tip 31 of the second wick portion 22 to the inner surface 18 facing the tip 31 was 50% or more and less than 100%, but instead, for example, it may be 30% or more and less than 50%.

[0057] In the above embodiments of the heat pipe, the top 23 of the first wick portion 21 was in contact with one of the inner surfaces 16. However, depending on the operating conditions of the heat pipe, the top 23 of the first wick portion 21 may not be in contact with the inner surface of the container 10. That is, the first wick portion 21 only needs to have a thickness of 50% or more of the height H of the internal space 15 of the container 10, and may have a thickness of less than 100% of the height H of the internal space 15 of the container 10. [Industrial applicability]

[0058] The heat pipe of the present invention has excellent fluid flow characteristics and exhibits excellent heat transport characteristics while preventing the generation of abnormal noise during fluid flow. Therefore, it is highly valuable for use in cooling electronic components such as semiconductor elements mounted on portable electrical and electronic devices whose installation position is prone to change. [Explanation of Symbols]

[0059] 1, 2, 3, 4 Heat pipes 10 containers 11 One end 13 The other end 20 Wick Structures 21 First wick section 22 Second Wick Section 30 Flat area 40 Gradual change part

Claims

1. A container that is a tube, with the end faces of one end sealed to the end faces of the other end, A wick structure provided inside the container, The working fluid sealed inside the container, A heat pipe equipped with, In at least one cross-section of the container perpendicular to its longitudinal direction, the wick structure comprises a first wick portion and a second wick portion that is integral with the first wick portion, extends outward from the first wick portion, and is thinner than the first wick portion. The second wick portion has a flat portion that extends along a direction perpendicular to the height direction of the internal space of the container, The first wick section and the second wick section have different average particle sizes of powder. In the aforementioned cross-section, the wick structure has a gradually changing section between the top of the first wick portion and the flat portion, along a direction perpendicular to the height direction of the internal space of the container, in which the thickness of the wick structure continuously decreases. Heat pipe.

2. The heat pipe according to claim 1, wherein the first wick portion and the second wick portion are composed of powders of different material types.

3. The heat pipe according to claim 1 or 2, wherein the first wick portion has a thickness of 50% or more of the height of the internal space of the container, and the second wick portion has a thickness of less than 50% of the height of the internal space of the container.

4. The heat pipe according to any one of claims 1 to 3, wherein at least a portion of the container has a flattened portion.

5. The heat pipe according to claim 4, wherein the flattened portion has one inner surface and another inner surface facing the first inner surface in the height direction of the internal space of the container, and in one cross-section, the first wick portion has a top portion in contact with the first inner surface and a bottom portion in contact with the other inner surface.

6. The heat pipe according to any one of claims 1 to 5, wherein in one cross-section, the ratio of the width of the second wick to the sum of the width of the second wick and the width from the tip of the second wick to the inner surface of the container facing the tip of the second wick is 50% or more.

7. The heat pipe according to any one of claims 1 to 6, wherein the tip of the second wick portion is not in contact with the inner surface of the container opposite to the tip of the second wick portion.

8. The heat pipe according to any one of claims 1 to 7, wherein in one cross-section, the ratio of the cross-sectional area of ​​the second wick portion to the cross-sectional area of ​​the first wick portion is 1.0% or more and 50% or less.

9. The heat pipe according to any one of claims 1 to 8, wherein the container has an evaporation section thermally connected to a heating element and a condensation section thermally connected to a heat exchange means, and the thickness of the flat portion in the evaporation section is greater than the thickness of the flat portion in the condensation section.

10. The heat pipe according to any one of claims 1 to 9, wherein in one cross-section, the ratio of the cross-sectional area of ​​the internal space of the container not occupied by the wick structure to the cross-sectional area of ​​the wick structure is 15% or more and 65% or less.

11. The heat pipe according to any one of claims 1 to 10, wherein the wick structure is a sintered body of metal powder.

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