Heat pipe

Abstract

This heat pipe comprises a container inside which a working fluid is sealed, and a wick accommodated in the container, wherein: the heat pipe includes, in different locations in a longitudinal direction of the container, an evaporation portion, a condensation portion, and an intermediate portion between the evaporation portion and the condensation portion; and in a cross section orthogonal to the longitudinal direction, the shape of the wick in the intermediate portion differs from the shape of the wick in the evaporation portion and the condensation portion, the wick in the evaporation portion and the condensation portion having an annular shape, and having a thin-walled part and a thick-walled part having a thickness greater than that of the thin-walled part.

Description

heat pipe

[0001] This application claims priority to Japanese Patent Application No. 2023-054784, filed on March 30, 2023, the contents of which are incorporated herein by reference.

[0002] A heat pipe such as that shown in Patent Document 1 has been known. The heat pipe includes a container in which a working fluid is sealed and a wick disposed within the container. The wick is provided to return the liquid-phase working fluid from the condenser to the evaporator. In Patent Document 1, the thickness of the wick varies along the longitudinal direction of the heat pipe.

[0003] U.S. Patent No. 7,520,315

[0004] In the configuration of Patent Document 1, the thickness of the wick is constant in a cross section perpendicular to the longitudinal direction of the container. By making the wick thickness constant, the flow resistance of the working fluid in the wick can be made uniform in the circumferential direction, but in this case, the thermal resistance due to the thickness of the wick may become large.

[0005] The present invention was made in consideration of these circumstances, and aims to provide a heat pipe that can simultaneously reduce the flow resistance of the working fluid in the wick and reduce the thermal resistance of the wick.

[0006] In order to solve the above problems, aspect 1 of the present invention is a heat pipe comprising a container in which a working fluid is sealed and a wick housed in the container, and having an evaporator section, a condenser section, and an intermediate section between the evaporator section and the condenser section at different locations in the longitudinal direction of the container, and in a cross section perpendicular to the longitudinal direction, the shape of the wick at the intermediate section is different from the shape of the wick in the evaporator section and the condenser section, and in the evaporator section and the condenser section, the wick is annular and has a thin section and a thick section that is thicker than the thin section.

[0007] This configuration improves the reflux performance of the working fluid because the thermal resistance in the thin part of the wick is low and the flow resistance in the thick part is low, thereby increasing the amount of heat transported and the distance of heat transport in the heat pipe.

[0008] A second aspect of the present invention is the heat pipe of the first aspect, wherein the thickness of the wick in the evaporator section and the condenser section varies gradually along the circumferential direction.

[0009] Furthermore, aspect 3 of the present invention is a heat pipe according to aspect 1 or 2, wherein in one cross-section, there are two valley portions where the thickness of the wick changes from decreasing to increasing in the circumferential direction, and there are two peak portions where the thickness of the wick changes from increasing to decreasing in the circumferential direction.

[0010] A fourth aspect of the present invention is the heat pipe of any one of the first to third aspects, wherein the center of the internal space of the wick and the central axis of the heat pipe are disposed at different positions.

[0011] A fifth aspect of the present invention is the heat pipe of any one of the first to fourth aspects, wherein the thickness of the wick in the circumferential direction is uniform in the intermediate portion.

[0012] According to the above aspect of the present invention, it is possible to provide a heat pipe that can reduce both the flow resistance of the working fluid in the wick and the thermal resistance of the wick.

[0013] Fig. 1 is a side view of a heat pipe according to a first embodiment. Fig. 2 is a cross-sectional view of the heat pipe shown in Fig. 1 taken along II-II, showing a cross-sectional view at an evaporator section. Fig. 3 is a cross-sectional view of the heat pipe shown in Fig. 1 taken along III-III, showing a cross-sectional view at an intermediate section. Fig. 4 is a cross-sectional view of the evaporator section of a heat pipe according to a second embodiment. Fig. 5 is a cross-sectional view of the evaporator section of a heat pipe according to a third embodiment. Fig. 6 is a cross-sectional view of a heat pipe according to a modified example of the first to third embodiments. Fig. 7 is a cross-sectional view of a heat pipe according to another modified example of the first to third embodiments.

[0014] First Embodiment The configuration of a heat pipe 1 according to this embodiment will be described below with reference to the drawings. As shown in FIGS. 1, 2, and 3, the heat pipe 1 includes a wick 20 and a container 30. The container 30 has an elongated shape extending in one direction. The wick 20 is housed in the container 30. A working fluid (not shown) is sealed within the container 30. The heat pipe 1 is a heat transport element that receives heat from, for example, a heat source 110 and transports the heat by utilizing the latent heat of the working fluid sealed within the container 30.

[0015] (Direction Definition) In this specification, the direction in which the container 30 extends is simply referred to as the longitudinal direction X. A cross section of the container 30 perpendicular to the longitudinal direction X is referred to as a transverse cross section. In addition, in the transverse cross section perpendicular to the longitudinal direction X of the container 30, a direction perpendicular to the central axis O is referred to as a radial direction, and a direction going around the central axis O is referred to as a circumferential direction.

[0016] As shown in FIG. 1 , the container 30 is a vessel whose both ends in the longitudinal direction X are sealed. As shown in FIGS. 2 and 3 , the container 30 is a cylindrical hollow vessel. The container 30 has an inner circumferential surface 31 facing radially inward and an outer circumferential surface 32 facing radially outward. The material of the container 30 can be appropriately selected depending on conditions such as the type of working fluid and the operating temperature. For example, the container 30 is formed of a metal such as copper, steel, or aluminum. In particular, using a metal material with high thermal conductivity such as copper or aluminum can improve heat transport and thermal diffusion. In this embodiment, a copper pipe is used as the container 30.

[0017] The inner diameter and the outer diameter of the container 30 are each substantially constant in the longitudinal direction X. Note that, at the ends 1 a and 1 b of the heat pipe 1 in the longitudinal direction X, the outer diameter of the container 30 may gradually decrease toward the end faces.

[0018] A working fluid is sealed inside the container 30. The working fluid is a known heat transport medium capable of changing phases, and changes between a liquid phase and a gas phase within the container 30. Examples of the working fluid that can be used include water, alcohol, ammonia, and alternative chlorofluorocarbons. The type of working fluid may be changed as appropriate depending on the temperature range of heat transported by the heat pipe 1 and the amount of heat transported. In this specification, a working fluid in the liquid phase may be referred to as a "working liquid," and a working fluid in the gas phase may be referred to as "vapor." Furthermore, when no particular distinction is made between the liquid phase and the gas phase, the term "working fluid" will be used.

[0019] A wick 20 is disposed within the container 30. The wick 20 extends over the entire length of the container 30 in the longitudinal direction X. The wick 20 is formed in an annular shape along the inner circumferential surface 31 of the container 30, as shown in FIGS. 2 and 3 , for example. The wick 20 covers the entire inner circumferential surface 31 of the container 30. Note that the wick 20 may not be formed in a partial circumferential region of the inner circumferential surface 31 of the container 30. For example, in cross section, the annular wick 20 may have a C-shape. The wick 20 has numerous pores capable of generating capillary force in the liquid-phase working fluid. These pores are used as liquid flow paths for the working fluid to flow, and serve as return paths (hereinafter referred to as "flow paths") for returning the working fluid from the condenser 5 to the evaporator 4 (described later). The working fluid in the flow paths flows in the longitudinal direction X and the circumferential direction due to capillary force.

[0020] The wick 20 is formed, for example, by bundling a plurality of thin metal wires, such as thin copper wires. The thin copper wires are linear bodies extending in the longitudinal direction X of the container 30. The outer diameter of the thin copper wires is, for example, several μm to several hundred μm. Pores extending in the longitudinal direction X are formed between the thin copper wires. These pores are used as the liquid flow paths described above. Furthermore, the working fluid also flows in the circumferential direction of the heat pipe 1 as the working fluid moves between the pores extending in the longitudinal direction X. The wick 20 is not limited to thin metal wires, and may be a metal mesh (mesh-like body), a sintered body of metal powder, or a mixture thereof.

[0021] Examples of metals that constitute the wick 20 include copper, aluminum, stainless steel, and alloys thereof. The wick 20 is not limited to being made of metal, and may be made of a carbon material or the like. For example, the wick 20 may be made of fine carbon wires, carbon mesh, or the like.

[0022] As shown in FIG. 1 , the heat pipe 1 has a first end 1 a and a second end 1 b, which are ends of the container 30 in the longitudinal direction X. The heat pipe 1 has an evaporator section 4 where working fluid evaporates to generate vapor, and a condenser section 5 where the vapor generated in the evaporator section 4 condenses to generate working fluid. The evaporator section 4 and the condenser section 5 are spaced apart in the longitudinal direction X. In this embodiment, the evaporator section 4 is provided at the first end 1 a of the container 30. The condenser section 5 is provided at the second end 1 b of the container 30. The heat pipe 1 has an intermediate section 6 between the evaporator section 4 and the condenser section 5. In this embodiment, the shape of the wick 20 in the intermediate section 6 is different from the shapes of the wick 20 in the evaporator section 4 and the condenser section 5. The shapes of the wick 20 in the evaporator section 4, the condenser section 5, and the intermediate section 6 will be described below with reference to FIGS. 2 and 3 .

[0023] 2 is a cross-sectional view of the evaporation section 4 of the heat pipe 1. In the cross-section, the radial dimension of the wick 20 in the evaporation section 4 is not constant in the circumferential direction. Hereinafter, the radial dimension of the wick 20 will be simply referred to as the thickness of the wick 20. In the evaporation section 4, the wick 20 has thin sections 20a and thick sections 20b that are thicker than the thin sections 20a. The thin sections 20a and thick sections 20b are alternately arranged in the circumferential direction.

[0024] In this embodiment, the wick 20 has two thin-walled portions 20a and two thick-walled portions 20b. In a cross section, the thickness of the wick 20 is thinnest at the circumferential center of the thin-walled portion 20a, and thickest at the circumferential center of the thick-walled portion 20b. That is, in a cross section, the circumferential center of the thin-walled portion 20a forms a valley portion 20a1 where the thickness of the wick 20 changes from decreasing to increasing in the circumferential direction, and the circumferential center of the thick-walled portion 20b forms a peak portion 20b1 where the thickness of the wick 20 changes from increasing to decreasing in the circumferential direction. In other words, the wick 20 has two valley portions 20a1 and two peak portions 20b1. The thickness of the wick 20 gradually increases from the valley portion 20a1 toward the peak portion 20b1. Therefore, in a cross section, the inner circumferential surface 21 of the wick 20 is curved. The two thin portions 20a are opposed to each other in the radial direction across the central axis O. The direction passing through the central axis O and penetrating the centers of the two thin portions 20a is defined as the A-axis direction. The two thick portions 20b are opposed to each other in the radial direction around the central axis O. The direction passing through the central axis O and penetrating the centers of the two thick portions 20b is defined as the B-axis direction. The A-axis direction and the B-axis direction are perpendicular to each other. Because the thin portions 20a and thick portions 20b of the wick 20 are arranged as described above, in this embodiment, the internal space 11 of the wick 20 has an elliptical shape in cross section with the A-axis as the major axis and the B-axis as the minor axis. Furthermore, the center of the ellipse where the A-axis and the B-axis intersect coincides with the central axis O.

[0025] The A-axis direction and the B-axis direction do not have to be perpendicular to each other. Furthermore, the number of thin-walled portions 20a and thick-walled portions 20b in one cross section is not limited to two each, and may be one each, or three or more each. In the present embodiment, the central portion and the valley portion 20a1 of the thin-walled portion 20a are aligned in the circumferential direction. However, the central portion and the valley portion 20a1 may be located at different positions in the circumferential direction of the thin-walled portion 20a. Similarly, the central portion and the peak portion 20b1 of the thick-walled portion 20b may be located at different positions in the circumferential direction. Furthermore, the number of valley portions 20a1 and the peak portions 20b1 in one cross section is not limited to two each, and may be one each, or three or more each. The shape of the internal space 11 in the cross section is not limited to an ellipse, and may be a circle, a shape combining multiple ellipses, or a polygon, depending on the number, arrangement, and shape of the thin-walled portions 20a and the thick-walled portions 20b.

[0026] FIG. 3 is a cross-sectional view of the heat pipe 1 at the intermediate portion 6. The shape of the wick 20 at the intermediate portion 6 is different from the shape of the wick 20 at the evaporation portion 4. At the intermediate portion 6, the thickness of the wick 20 is constant in the circumferential direction. That is, the shape of the internal space 11 at the cross section is circular. In this embodiment, the thickness of the wick 20 at the intermediate portion 6 is greater than the maximum thickness of the wick 20 at the evaporation portion 4 (i.e., the thickness of the peak portion 20b1). Note that the thickness of the wick 20 at the intermediate portion 6 may be equal to the maximum thickness of the wick 20 at the evaporation portion 4. The thickness of the wick 20 at the intermediate portion 6 may be smaller than the maximum thickness of the wick 20 at the evaporation portion 4 and larger than the minimum thickness of the wick 20 (i.e., the thickness of the valley portion 20a1).

[0027] In this embodiment, the shape of the wick 20 in the cross section of the condenser section 5 is the same as that of the evaporator section 4. Therefore, detailed description will be omitted. Note that the cross-sectional shapes of the wick 20 in the evaporator section 4 and the condenser section 5 may be different from each other. For example, in the condenser section 5, the minimum thickness of the thin section 20a and the maximum thickness of the thick section 20b may be different from those in the evaporator section 4.

[0028] As described above, the shape of the wick 20 in cross section is different in the intermediate section 6 compared to the evaporation section 4 and the condensation section 5, so that the thickness of the wick 20 changes gradually in at least a portion in the longitudinal direction X.

[0029] [Heat Transport Cycle by Heat Pipe 1] Next, a description will be given of the operation of the heat pipe 1 configured as above. As shown in FIG. 1 , a heat transport device 100 includes a heat pipe 1, a heat source 110, and a cooling unit 120.

[0030] The heat source 110 is in direct or indirect contact with the evaporation section 4 of the heat pipe 1. The heat source 110 heats the portion of the container 30 corresponding to the evaporation section 4. The heat source 110 is, for example, an electronic component (e.g., a CPU) of an electronic device. The cooling section 120 is in direct or indirect contact with the condensation section 5 of the heat pipe 1. The cooling section 120 cools the portion of the container 30 corresponding to the condensation section 5. The cooling section 120 is, for example, a heat dissipation structure such as a heat sink. A thermally conductive member (not shown) may be provided between the heat source 110 and the container 30 and between the cooling section 120 and the container 30. The thermally conductive member may be, for example, a grease layer.

[0031] When the heat pipe 1 is heated by the heat source 110, the working fluid permeating the flow path of the wick 20 is heated and evaporated in the evaporation section 4, becoming vapor. The vapor generated in the evaporation section 4 flows through the internal space 11 toward the condensation section 5, which has a lower pressure and temperature than the evaporation section 4. In the condensation section 5, the heat pipe 1 is cooled by the cooling section 120, and a portion of the vapor condenses to become working fluid. The working fluid generated in the condensation section 5 permeates the flow path of the wick 20. The working fluid liquefied in the condensation section 5 flows through the flow path of the wick 20 and is returned to the evaporation section 4 from the condensation section 5 via the intermediate section 6.

[0032] As shown in FIG. 1 , the heat pipe 1 is arranged so that the A-axis direction intersects the heat source 110 and the cooling section 120. In this case, one thin-walled portion 20a of the wick 20 is arranged in the evaporation section 4 closest to the heat source 110. The thin-walled portion 20a is thinner than the thick-walled portion 20b and has lower thermal resistance, allowing the heat generated by the heat source 110 to be efficiently transferred toward the interior of the heat pipe 1. That is, the thin-walled portion 20a allows the working fluid to evaporate efficiently. Furthermore, thick-walled portions 20b are provided on both sides of the thin-walled portion 20a in the circumferential direction. Because the wick 20 is thicker in the thick-walled portion 20b than the thin-walled portion 20a, the flow resistance of the working fluid is lower. Therefore, the working fluid moving from the condensation section 5 can smoothly move through the thick-walled portion 20b, which has lower flow resistance, and the working fluid can be efficiently supplied from the thick-walled portion 20b toward the thin-walled portion 20a, where a large amount of evaporation of the working fluid occurs.

[0033] Furthermore, in the condenser section 5, one thin section 20a of the wick 20 is disposed closest to the cooling section 120. The thin section 20a is thinner than the thick section 20b of the wick 20 and has lower thermal resistance, allowing heat to be efficiently transferred from the interior of the heat pipe 1 toward the cooling section 120. That is, the thin section 20a allows efficient phase change of vapor to liquid working fluid. In the two thick sections 20b that sandwich the thin section 20a in the circumferential direction, the wick 20 is thicker than the thin section 20a, so the flow resistance of the working fluid is lower. Therefore, the working fluid liquefied in the thin section 20a can be smoothly transferred toward the thick section 20b.

[0034] Furthermore, when the working fluid liquefied in the condenser section 5 flows through the flow path of the wick 20 and returns from the condenser section 5 to the evaporator section 4 via the intermediate section 6, the thickness of the wick 20 changes gradually in the longitudinal direction X, allowing the working fluid to move smoothly. Furthermore, in the intermediate section 6, the thickness of the wick 20 is uniform around the entire circumferential direction, so the flow resistance of the working fluid is small and the working fluid can be suitably moved from the condenser section 5 to the evaporator section 4. By circulating the working fluid within the heat pipe 1 including the wick 20 with the thin section 20a and the thick section 20b formed in this way, heat from the heat source 110 can be efficiently transported to the cooling section 120.

[0035] As described above, the heat pipe 1 of this embodiment comprises a container 30 in which a working fluid is sealed, and a wick 20 housed in the container 30, and has an evaporation section 4, a condensation section 5, and an intermediate section 6 between the evaporation section 4 and the condensation section 5 at different locations in the longitudinal direction X of the container 30, and in a cross section perpendicular to the longitudinal direction X, the shape of the wick 20 in the intermediate section 6 is different from the shape of the wick 20 in the evaporation section 4 and the condensation section 5, and in the evaporation section 4 and the condensation section 5, the wick 20 is annular and has a thin section 20a and a thick section 20b that is thicker than the thin section 20a.

[0036] In the wick 20 of this embodiment, the thermal resistance in the thin portion 20a is small, and the flow resistance in the thick portion 20b is small, so it is possible to reduce both the flow resistance of the working fluid in the wick 20 and the thermal resistance of the wick 20. This improves the reflux performance of the working fluid, thereby increasing the amount of heat transport and the heat transport distance in the heat pipe 1.

[0037] Furthermore, the thickness of the wick 20 gradually changes in the circumferential direction in the evaporation section 4 and the condensation section 5. This reduces the flow resistance of the working fluid, allowing the working fluid to move smoothly from the thick section 20b to the thin section 20a in the evaporation section 4, and from the thin section 20a to the thick section 20b in the condensation section 5.

[0038] In addition, in one cross section, there are two valleys 20a1 where the thickness of the wick 20 changes from decreasing to increasing in the circumferential direction, and there are two peaks 20b1 where the thickness of the wick 20 changes from increasing to decreasing in the circumferential direction. This allows the thin-walled portions 20a to be suitably positioned with respect to the heat source 110 and the cooling portion 120 to efficiently transport heat.

[0039] Furthermore, the thickness of the wick 20 in the circumferential direction is uniform in the intermediate portion 6. This reduces the flow resistance of the working fluid in the intermediate portion 6, allowing the working fluid to move smoothly from the condensation portion 5 to the evaporation portion 4.

[0040] Second Embodiment Next, a second embodiment of the present invention will be described. The basic configuration is the same as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and their description will be omitted. Only the differences will be described. Figure 4 shows a heat pipe 1 according to the second embodiment. This embodiment differs from the heat pipe 1 of the first embodiment in that the shape of the internal space 11 in the evaporator section 4 and the condenser section 5 of the heat pipe 1 is not elliptical.

[0041] FIG. 4 is a cross-sectional view of the evaporator section 4 of the heat pipe 1 according to the second embodiment. The cross-section of the condenser section 5 of the heat pipe 1 according to the second embodiment is similar to FIG. 4 and is therefore not shown. In the evaporator section 4 and the condenser section 5 of the heat pipe 1 according to the second embodiment, the thickness of the wick 20 in the thick-walled section 20b is uniform in the circumferential direction. Furthermore, in the thin-walled section 20a, the thickness is thinnest at the circumferential center (valley section 20a1) of the thin-walled section 20a and gradually increases toward the thick-walled section 20b. At the circumferential end of the thin-walled section 20a, the thickness of the wick 20 is equal to the thickness of the thick-walled section 20b. Therefore, in this embodiment, the entire length of the thick-walled section 20b in the circumferential direction corresponds to the peak section 20b1. As a result, the shape of the internal space 11 is a combination of an ellipse with its major axis in the A-axis direction and a circle centered on the central axis O.

[0042] In this way, in the heat pipe 1 of this embodiment, the thickness of the thick portion 20b is constant in the evaporator section 4 and the condenser section 5, so that the flow resistance in the thick portion 20b can be further reduced.

[0043] Third Embodiment Next, a third embodiment of the present invention will be described. The basic configuration is the same as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and their description will be omitted. Only the differences will be described. Figure 5 shows a heat pipe 1 according to the third embodiment. This embodiment differs from the heat pipe 1 of the first embodiment in that the number of thin-walled portions 20a and thick-walled portions 20b in the evaporator section 4 and condenser section 5 of the heat pipe 1 is one each. In other words, the number of valley portions 20a1 and peak portions 20b1 is one each.

[0044] FIG. 5 is a cross-sectional view of the evaporator section 4 of a heat pipe 1 according to a third embodiment. The cross-section of the condenser section 5 of the heat pipe 1 according to the third embodiment is similar to that shown in FIG. 5 and is therefore not shown. As shown in FIG. 5 , the internal space 11 of the wick 20 of the heat pipe 1 according to the third embodiment is circular. The center O1 of the internal space 11 is located at a position different from the central axis O of the heat pipe 1. Because the central axis O and the center O1 are different, a thin portion 20a and a thick portion 20b are formed in the wick 20. For example, in the longitudinal direction X, the center O1 may gradually approach the central axis O from the ends 1a and 1b of the heat pipe 1 toward the intermediate section 6, and the center O1 and the central axis O may coincide at the center of the heat pipe 1 in the longitudinal direction X. In the heat pipe 1 according to this embodiment, the thin portion 20a of the evaporator section 4 may be disposed adjacent to the heat source 110, and the thin portion 20a of the condenser section 5 may be disposed adjacent to the cooling section 120 in the heat transport device 100.

[0045] As described above, in the heat pipe 1 of this embodiment, the center O1 of the internal space 11 of the wick 20 is located at a different position from the central axis O of the heat pipe 1. This allows the cross-sectional area of ​​the thick-walled portion 20b to be larger, thereby enabling more efficient transport of the working fluid.

[0046] The technical scope of the present invention is not limited to the above-described embodiments or examples, and various modifications can be made without departing from the spirit of the present invention.

[0047] For example, the wick 20 may have a thin portion 20 a and a thick portion 20 b along the entire length in the longitudinal direction X. In addition, the shape of the wick 20 in the intermediate portion 6 in the cross section may be the same as the shape of the wick 20 in the evaporation section 4 and the condensation section 5.

[0048] Furthermore, the wick 20 may have a thin portion 20a and a thick portion 20b in at least one cross section along the entire length of the heat pipe 1 in the longitudinal direction X. For example, only the evaporation section 4 may have the thin portion 20a and the thick portion 20b, and the thickness of the wick 20 may be constant throughout the entire circumference in the intermediate section 6 and the condensation section 5. Alternatively, only the condensation section 5 may have the thin portion 20a and the thick portion 20b, and the thickness of the wick 20 may be constant throughout the entire circumference in the intermediate section 6 and the evaporation section 4. In this case, it is sufficient that the shape of the wick 20 in the intermediate section 6 in the cross section is different from the shape of the wick 20 in at least one of the evaporation section 4 and the condensation section 5.

[0049] 6 and 7, the container 30 may have a rectangular cross section. For example, the dimension of the container 30 in the B-axis direction is larger than the dimension in the A-axis direction, and the surface area of ​​the first surface 32a of the outer circumferential surface 32 of the container 30 facing the A-axis direction is larger than that of the second surface 32b facing the B-axis direction. The first surface 32a has a thin-walled portion 20a, which provides a lower thermal resistance than the second surface 32b, and the surface area of ​​the first surface 32a is larger than that of the second surface 32b. Therefore, when the heat source 110 and the cooling unit 120 are disposed on the first surface 32a, heat can be transported more efficiently.

[0050] 6, the internal space 11 may have an elliptical shape with the A axis as the minor axis and the B axis as the major axis. Alternatively, as shown in Fig. 7, the internal space 11 may have a rectangular shape. That is, in the cross section, the thin-walled portion 20a may have a uniform thickness, and the thick-walled portion 20b, which is thicker than the thin-walled portion 20a, may also have a uniform thickness.

[0051] 1 illustrates an example in which one thin portion 20a of the wick 20 is placed close to one heat source 110, but multiple heat sources 110 may be placed corresponding to the positions where multiple thin portions 20a are placed. For example, two heat sources 110 may be placed in the evaporation section 4, facing each other in the A-axis direction with the central axis O in between. The same applies to the number and placement of the cooling sections 120 in the condensation section 5. The entire circumference of the evaporation section 4 may be covered by the heat source 110, or the entire circumference of the condensation section 5 may be covered by the cooling section 120.

[0052] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention, and the above-described embodiments and variations may be combined as appropriate.

[0053] 1...heat pipe, 4...evaporation section, 5...condensation section, 6...intermediate section, 11...internal space, 20...wick, 20a...thin section, 20a1...valley section, 20b...thick section, 20b1...peak section, 30...container, X...longitudinal direction, O...central axis, O1...center of internal space

Claims

1. a container in which a working fluid is sealed; a wick contained within the container, The container has an evaporation section, a condensation section, and an intermediate section between the evaporation section and the condensation section at different positions in the longitudinal direction of the container, In a cross section perpendicular to the longitudinal direction, the shape of the wick in the intermediate section is different from the shapes of the wick in the evaporation section and the condensation section, In the evaporator section and the condenser section, the wick is annular and has a thin portion and a thick portion that is thicker than the thin portion.

2. The heat pipe according to claim 1 , wherein the thickness of the wick gradually changes along the circumferential direction in the evaporator section and the condenser section.

3. 3. A heat pipe as described in claim 1 or 2, wherein in one cross-section, there are two valley portions where the thickness of the wick changes from decreasing to increasing in the circumferential direction, and there are two peak portions where the thickness of the wick changes from increasing to decreasing in the circumferential direction.

4. 3. The heat pipe according to claim 1, wherein the center of the internal space of the wick and the central axis of the heat pipe are disposed at different positions.

5. The heat pipe according to claim 1 , wherein the thickness of the wick in the circumferential direction is uniform in the intermediate portion.