Heat pipe

Abstract

To provide a heat pipe capable of improving efficiency of reflux of working fluid and this has excellent heat transporting characteristic.SOLUTION: A heat pipe 1 includes, in a container 2 having an internal space S in which working fluid F is sealed: an evaporation portion 3 for evaporating liquid-phase working fluid FL for phase change to vapor-phase working fluid Fg; a condensation portion 4 disposed at a position separated from the evaporation portion 3, for condensing the vapor-phase working fluid Fg for phase change to the liquid-phase working fluid FL; and an intermediate portion 5 positioned between the evaporation portion 3 and the condensation portion 4. The heat pipe further has, viewed in a transverse section of the evaporation portion 3: a first sintered body layer 6 composed of a sintered body of first copper powder and formed on a specific region on an inner peripheral face 2a of the container 2; and a second sintered body layer 7 composed of a sintered body of second copper powder having an average particle size larger than that of the first copper powder, and annularly formed over the whole inner peripheral face 2a of the container 2 in a state that the first sintered body layer 6 is interposed between itself and the inner peripheral face 2a of the container 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heat pipe having heat transport properties. [Background technology]

[0002] In recent years, electronic components such as semiconductor elements mounted in electric and electronic devices such as notebook computers, digital cameras, and mobile phones tend to generate more heat due to the high density mounting that accompanies higher functionality, so it is important to adopt a configuration that can cool them efficiently. One method for cooling electronic components is to use a heat pipe, for example.

[0003] Here, a heat pipe generally includes a tubular vessel (container) having an internal space in which a working fluid is sealed. The tubular vessel has an evaporator at one end for evaporating the liquid phase working fluid to change it to a gas phase working fluid, and a condenser at the other end for condensing the gas phase working fluid to change it to a liquid phase working fluid. The working fluid that has changed from liquid to gas phase in the evaporator flows from the evaporator to the condenser. The working fluid that has changed from gas to liquid phase in the condenser flows from the condenser to the evaporator. In this way, a circulating flow is formed by the reflux of the working fluid between the evaporator and condenser in the tubular vessel, thereby transporting heat between the evaporator and condenser in the tubular vessel.

[0004] As a conventional heat pipe, for example, Patent Document 1 describes a heat pipe comprising a pipe body having a sealed hollow portion, a porous metal layer arranged so as to be in contact with the inner circumferential surface of the pipe body, and a working fluid sealed within the pipe body, in which the porous metal layer has a first porous portion partitioned in its circumferential direction and a second porous portion having a smaller porosity than the first porous portion. In this heat pipe, the liquid phase working fluid is moved mainly by the first porous portion, and heat exchange between the pipe body and the working fluid is achieved mainly by the second porous portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-148886 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the heat pipe described in Patent Document 1, the working fluid changes phase from liquid to gas in the second porous section, but in order to keep up with the increasing heat generation of electronic devices, it is necessary to efficiently circulate a larger amount of working fluid. In this case, if the thickness of the second porous section is increased, it is possible to increase the efficiency of the reflux of the working fluid, but this narrows the hollow section through which the gas-phase working fluid flows, and instead reduces the heat transport properties of the heat pipe.

[0007] An object of the present invention is to provide a heat pipe capable of increasing the efficiency of reflux of a working fluid, thereby providing excellent heat transport properties. [Means for solving the problem]

[0008] In order to achieve the above object, the gist of the present invention is as follows. (1) A heat pipe comprising a container having an internal space filled with a working fluid, an evaporator section for evaporating a liquid-phase working fluid to change its phase to a gas-phase working fluid, a condenser section disposed at a position spaced apart from the evaporator section for condensing the gas-phase working fluid to change its phase to a liquid-phase working fluid, and an intermediate section located between the evaporator section and the condenser section, the heat pipe having, when viewed in cross section of the heat pipe in the evaporator section, a first sintered body layer made of a sintered body of a first copper powder and formed in a specific region on an inner circumferential surface of the container, and a second sintered body layer made of a sintered body of a second copper powder having an average particle size larger than that of the first copper powder and formed in an annular shape over the entire inner circumferential surface of the container with the first sintered body layer interposed between the first sintered body layer and the inner circumferential surface of the container. (2) A heat pipe as described in (1) above, wherein, when viewed in a vertical cross section including the longitudinal direction of the heat pipe, the arrangement length of the first sintered body layer is longer than the longitudinal dimension of the evaporator section, and the arrangement length of the second sintered body layer is longer than the arrangement length of the first sintered body layer. (3) The heat pipe according to (2) above, wherein the second sintered layer terminates at any position in the intermediate portion. (4) A heat pipe as described in (3) above, in which the liquid-phase working fluid that has undergone a phase change in the condensation section flows toward the evaporation section by capillary force through the internal voids of the second sintered body layer located in the middle section, and flows from the second sintered body layer toward the first sintered body layer through the contact interface between the outer circumferential surface of the second sintered body layer and the inner circumferential surface of the first sintered body layer. (5) The heat pipe according to any one of (1) to (4) above, wherein the specific region includes a region of an inner circumferential surface of the container that constitutes a portion facing a heating element. (6) The heat pipe according to any one of (1) to (5) above, wherein a plurality of grooves extending along the longitudinal direction of the container are formed on an inner circumferential surface of the container. (7) The heat pipe according to (6) above, wherein the first sintered layer is also filled into the grooves located in the specific region. (8) A heat pipe as described in (6) or (7) above, wherein the second sintered body layer substantially isolates the vapor flow of the gas-phase working fluid that has undergone a phase change in the evaporator section from the liquid flow of the liquid-phase working fluid that has undergone a phase change in the condenser section, and the liquid flow is divided into a path that passes through the multiple grooves and a path that passes through internal voids in the second sintered body layer. Effect of the Invention

[0009] According to the present invention, it is possible to increase the efficiency of reflux of the working fluid, and thus to provide a heat pipe with excellent heat transport properties. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 shows the internal structure of the heat pipe of the first embodiment, where FIG. 1(a) is a longitudinal cross-sectional view, FIG. 1(b) is a cross-sectional view taken along line IA-IA in FIG. 1(a), and FIG. 1(c) is a cross-sectional view taken along line IB-IB in FIG. 1(a). [Diagram 2] FIG. 2 is a cross-sectional view illustrating the flow of working fluid that occurs inside the heat pipe of FIG. 1 during operation. [Diagram 3] Figure 3 shows the internal structure of the heat pipe of the second embodiment, where Figure 3(a) is a longitudinal cross-sectional view, Figure 3(b) is a cross-sectional view taken along line IIA-IIA in Figure 3(a), and Figure 3(c) is a cross-sectional view taken along line IIB-IIB in Figure 3(a). [Figure 4] FIG. 4 is a cross-sectional view showing the internal structure of a heat pipe according to an embodiment of the present invention and a comparative example, where FIG. 4(a) is a cross-sectional view of a heat pipe according to an embodiment of the present invention, and FIG. 4(b) is a cross-sectional view of a heat pipe according to the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, the heat pipe of some embodiments of the present invention will be described below.

[0012] <First embodiment> FIG. 1 is a diagram showing the internal structure of a heat pipe according to a first embodiment, in which FIG. 1(a) is a longitudinal sectional view, and FIG. 1(b) is an I of FIG. 1(a). A -I A Figure 1(c) is a cross-sectional view of the I line in Figure 1(a). B -I B 1 is a cross-sectional view taken along the line 14. On the other hand, FIG. 2 is a cross-sectional view illustrating the flow of a working fluid that occurs inside the heat pipe of FIG.

[0013] The heat pipe 1 is a heat pipe that supplies a liquid phase working fluid F to a container 2 having an internal space S in which the working fluid F is sealed. L is evaporated to produce gas phase working fluid F g and a vaporizer 3 for changing the phase of the working fluid F from the vaporizer 3 to the vapor phase.g is condensed to obtain the liquid phase working fluid F L and an intermediate section 5 located between the evaporation section 3 and the condensation section 4. When viewed in cross section at the evaporation section 3, the heat pipe 1 has a first sintered body layer 6 made of a sintered body of a first copper powder and formed in a specific region on the inner circumferential surface 2a of the container 2, and a second sintered body layer 7 made of a sintered body of a second copper powder having an average particle size larger than that of the first copper powder and formed in an annular shape over the entire inner circumferential surface 2a of the container 2 with the first sintered body layer 6 interposed between the first sintered body layer 6 and the inner circumferential surface 2a of the container 2.

[0014] In this heat pipe 1, a second sintered body layer 7 made of a second copper powder having a larger average particle size than the first copper powder is laminated on an inner circumferential surface 6a of a first sintered body layer 6 made of a first copper powder, and a liquid-phase working fluid F flows through voids in the second sintered body layer 7. L is supplied to the first sintered body layer 6, and the liquid phase working fluid F reaches the inner circumferential surface 6a of the first sintered body layer 6 and the voids formed therein. L As heat is transferred to the first sintered body layer 6, the liquid phase working fluid F L The working fluid F evaporates and becomes gas phase. g This allows heat exchange between the portion of the evaporator 3 where the first sintered body layer 6 is formed and the working fluid F. Therefore, the heat transferred to the portion of the evaporator 3 where the first sintered body layer 6 is formed is transferred to the gas-phase working fluid F. g In particular, when the evaporator 3 of the heat pipe 1 is viewed in a cross section perpendicular to the longitudinal direction X, the first sintered body layer 6 is formed in a specific region that is a part of the inner circumferential surface 2a of the container 2, and the second sintered body layer 7 is formed in an annular shape over the entire inner circumferential surface 2a of the container 2. As a result, the entire surface of the first sintered body layer 6 is covered with the liquid phase working fluid F. L The first sintered body layer 6 is covered with the second sintered body layer 7 through which the liquid phase working fluid F flows, and the contact area between the first sintered body layer 6 and the second sintered body layer 7 is increased, so that the liquid phase working fluid F flows over a wider area of ​​the inner circumferential surface 6a of the first sintered body layer 6. Lis supplied, it is possible to promote the return of the working fluid F. At the same time, since the area of ​​the part where the return is performed, i.e., the area where the second sintered body layer 7 is laminated, becomes large relative to the area where the first sintered body layer 6 is laminated on the inner circumferential surface 2a of the container 2, it is possible to increase the efficiency of the return of the working fluid F.

[0015] In this way, the heat pipe 1 efficiently converts the liquid phase working fluid F L Since the working fluid can be circulated, the efficiency of the circulating working fluid can be increased, thereby providing a heat pipe with excellent heat transport properties.

[0016] [About container configuration] 1 and 2 includes a container 2 having an internal space S in which a working fluid F is sealed. In FIGS. 1 and 2, a tubular vessel is shown as an example of the container 2.

[0017] Here, the extension shape of the container 2 in the longitudinal direction X is not particularly limited, and may be a straight line as shown in FIG. 1(a) or a curved shape such as an L-shape or a U-shape. The outer contour shape of the container 2 when cut in a direction perpendicular to the longitudinal direction X of the container 2 is not particularly limited, and may be a flat shape, a polygonal shape such as a square, or a substantially circular shape as shown in FIG. 1(b) and FIG. 1(c). The thickness of the container 2 is not particularly limited, and may be, for example, in the range of 0.05 mm to 1.0 mm. The outer diameter of the container 2 is not particularly limited, and may be, for example, in the range of 5 mm to 20 mm when the container 2 has an outer contour shape of a substantially circular shape as shown in FIG. 1(b) and FIG. 1(c).

[0018] The material of the container 2 is not particularly limited. In particular, when an aqueous liquid is used as the working fluid F, it is preferable to use a metal material from the viewpoint of improving wettability with the working fluid F. In particular, from the viewpoint of excellent thermal conductivity, for example, copper, copper alloys, etc. can be used for the container 2. Furthermore, from the viewpoint of weight reduction, for example, aluminum, aluminum alloys, etc. can be used for the container 2. Furthermore, from the viewpoint of high strength, for example, stainless steel, etc. can be used for the container 2. Furthermore, for example, tin, tin alloys, titanium, titanium alloys, nickel, nickel alloys, etc. may be used for the container 2 depending on the usage situation.

[0019] [About the configuration of the evaporation section, condensation section and intermediate section] The heat pipe 1 conveys a liquid phase working fluid F L is evaporated to produce gas phase working fluid F g and a vaporizer 3 for changing the phase of the working fluid F from the vaporizer 3 to the vapor phase. g is condensed to obtain the liquid phase working fluid F L and an intermediate section 5 located between the evaporation section 3 and the condensation section 4. Here, the evaporation section 3, the condensation section 4 and the intermediate section 5 can each be provided at a part along the longitudinal direction X of the container 2 as shown in Fig. 1(a). The container 2 shown in Fig. 1(a) has the evaporation section 3 at one end portion and the condensation section 4 at the other end portion, and has the intermediate section 5 between the evaporation section 3 and the condensation section 4, and is configured as a sealed tube.

[0020] Of these, the evaporation section 3 is formed at one end side portion of the container 2 in FIG. 1(a) and has a function of receiving (absorbing) heat from a heat generating body 9 thermally connected thereto. Specifically, the evaporation section 3, as shown in FIG. 2, for example, L is evaporated to produce gas phase working fluid F g By changing the phase of the liquid to the liquid phase, the liquid absorbs the heat received from the heating element 9 as latent heat of vaporization.

[0021] In the evaporation section 3, heat generated from the heating element 9 is transferred to the first sintered body layer 6 through the container 2, and then the heat is transferred from the first sintered body layer 6 to the second sintered body layer 7. On the other hand, as shown in FIG. 2, the liquid phase working fluid F L is supplied from the second sintered body layer 7 to the first sintered body layer 6 in the evaporation section 3. Therefore, the liquid phase working fluid F L Gas phase working fluid F g The phase change to the liquid phase of the working fluid F in the first sintered body layer 6 mainly occurs in the first sintered body layer 6, but may occur partially in the second sintered body layer 7. L The vapor phase of the working fluid F produced by evaporation of g The carbon dioxide moves into the internal space S through the voids formed inside the second sintered body layer 7.

[0022] The condenser 4 is disposed at a position separated from the evaporator 3, and is disposed at the other end of the container 2 in FIG. 1. The condenser 4 condenses the gas-phase working fluid F that has undergone a phase change in the evaporator 3 and has been transported. g The condenser 4 has a function of dissipating the latent heat of vaporization of the working fluid F by a heat exchanger (not shown). g is condensed to obtain the liquid phase working fluid F L The phase of the working fluid F is changed to 0.5, and the heat transported as the latent heat of condensation of the working fluid F is released to the outside of the heat pipe 1.

[0023] [Configuration of the first sintered layer] The first sintered layer 6 is made of a sintered body of a first copper powder, and is a sintered body layer formed in a specific region on the inner circumferential surface 2a of the container 2 when viewed in a cross section perpendicular to the longitudinal direction X of the heat pipe 1 in the evaporation section 3. The first sintered layer 6 is made of a sintered body of a first copper powder having a smaller average particle size than the second sintered layer 7 described later, and therefore has a smaller average particle size than the liquid phase working fluid F. L The gap through which the liquid phase working fluid F can flow is small. LThe flow rate of the working fluid F is slow. In addition, since the first sintered body layer 6 is adjacent to the inner circumferential surface 3a of the evaporation section 3 of the container 2, the temperature of the first sintered body layer 6 is likely to become relatively high. Therefore, the flow of the working fluid F in the first sintered body layer 6 is as shown in FIG. 2, in which the working fluid F in the liquid phase is supplied from the inner circumferential surface 6a side and permeates into the first sintered body layer 6. L and the flow of the liquid phase working fluid F that has penetrated into the first sintered body layer 6. L The gas phase working fluid F is generated by evaporation of the first sintered body layer 6 and flows from the inside of the first sintered body layer 6 through the inner circumferential surface 6a toward the internal space S. g The first sintered body layer 6 is configured such that the heat received (absorbed) from a heat generating body (not shown) thermally connected to the container 2 is transferred to the first sintered body layer 6, and the liquid phase working fluid F flows in the first sintered body layer 6 while the majority of the heat is retained on a specific area of ​​the inner circumferential surface 2a of the container 2. L Since the working fluid F evaporates, it is possible to efficiently change the phase of the working fluid F to a gas phase. Here, the specific region of the inner circumferential surface 2a of the container 2 can be a region including a region of the inner circumferential surface 2a constituting a portion of the container 2 facing the heating element 9.

[0024] As shown in FIG. 1(a), the first sintered body layer 6 is provided at least in the evaporation section 3. By providing such a first sintered body layer 6 in the evaporation section 3, the liquid phase working fluid F L Since the evaporation of the working fluid F is promoted, the heat received from the heating element 9 thermally connected to the evaporation section 3 can be absorbed by a larger amount of the working fluid F as latent heat of evaporation.

[0025] Here, the arrangement length L1 of the first sintered body layer 6 is preferably longer than the longitudinal dimension L0 of the evaporation section 3 when viewed in a vertical cross section including the longitudinal direction X of the heat pipe 1. As a result, the first sintered body layer 6 is provided adjacent to both the inner circumferential surface 3a of the evaporation section 3 and the inner circumferential surface 5a of the intermediate section 5. By configuring the arrangement length L1 of the first sintered body layer 6 in this manner, heat from the heating element 9 toward the intermediate section 5 can be conducted to the first sintered body layer 6 and absorbed by the working fluid F. In particular, from the viewpoint of efficiently absorbing heat from the heating element 9 toward the intermediate section 5 into the working fluid F, it is more preferable that the first sintered body layer 6 is arranged at least in the region of the inner circumferential surface 2a of the container 2 that constitutes the portion facing the heating element 9 and the region of the inner circumferential surface 2a of the container 2 adjacent to both sides of that region when viewed in vertical cross section. On the other hand, the upper limit of the length L1 of the first sintered body layer 6 is preferably 150 mm or less, from the viewpoint of facilitating the production of the first sintered body layer 6 by the production method described later.

[0026] In addition, it is preferable that the length of the portion of the inner circumferential surface 2a of the container 2 where the first sintered body layer 6 is disposed is longer than the region of the inner circumferential surface 2a that constitutes the portion facing the heating element 9, when viewed in a cross section perpendicular to the longitudinal direction X of the heat pipe 1. In particular, it is more preferable that the first sintered body layer 6 is disposed at least in the region of the inner circumferential surface 2a of the container 2 that constitutes the portion facing the heating element 9, and in the regions on the inner circumferential surface 2a of the container 2 adjacent to both sides of that region, when viewed in a cross section. By configuring the first sintered body layer 6 in this way, the heat transferred from the heating element 9 to the container 2 can be efficiently conducted to the first sintered body layer 6 and absorbed by the working fluid F.

[0027] In this specification, the inner circumferential surface refers to the surface along the wall surface on the side of the internal space S. In addition, in this specification, the outer circumferential surface refers to the surface along the wall surface on the side away from the internal space S. In addition, the longitudinal dimension L0 of the evaporation section 3 can be the size of the heating element 9 thermally connected to the heat pipe 1 along the longitudinal direction X of the heat pipe 1.

[0028] The first sintered body layer 6 is preferably formed of a sintered body of the first copper powder and is made of a porous material different from the bulk material. By forming the first sintered body layer 6 from a porous material, the surface area of ​​the first sintered body layer 6 is increased, so that the liquid phase working fluid F L In addition, by forming the first sintered layer 6 from a sintered body of copper powder, it is possible to improve the wettability with the working fluid F and increase the thermal conductivity.

[0029] Here, the average particle size (average primary particle size) of the first copper powder is not particularly limited, but may be, for example, in the range of 0.01 μm to 200 μm. The average particle size in this specification is the particle size at a volume-based integrated value of 50% in the particle size distribution measured by a laser diffraction scattering type particle size distribution measurement method. In addition, the thickness of the first sintered body layer 6 is not particularly limited, but may be, for example, in the range of 0.1 mm to 1 mm.

[0030] [About the composition of the second sintered layer] The second sintered body layer 7 is made of a sintered body of a second copper powder having a larger average particle size than the first copper powder, and is a sintered body layer formed in a ring shape over the entire inner circumferential surface 2a of the container 2 in a cross section perpendicular to the longitudinal direction X of the heat pipe 1 in the evaporation section 3, with the first sintered body layer 6 interposed between the second sintered body layer 7 and the inner circumferential surface 2a of the container 2. Here, the second sintered body layer 7 is layered on the inner circumferential surface 6a of the first sintered body layer 6, and is also layered on the inner circumferential surface 2a of the container 2 on which the first sintered body layer 6 is not layered, and these are positioned so as to extend continuously. Since the second sintered body layer 7 is made of a sintered body of a second copper powder having a larger average particle size than the first sintered body layer 6 described above, large voids are formed inside, and these voids are used to fill the liquid-phase working fluid F. L In order to form a flow path in which the liquid phase working fluid F L The second sintered body layer 7 is also a portion where the temperature is less likely to become high than the first sintered body layer 6. Therefore, when viewed in a cross section perpendicular to the longitudinal direction X of the heat pipe 1, the flow of the working fluid F inside the second sintered body layer 7 is as shown in FIG.L The flow of the working fluid F in the gas phase generated mainly in the first sintered body layer 6 along the inner peripheral surface 2a of the container. g The main flow is toward the internal space S.

[0031] As shown in Fig. 1(a), the length L2 of the second sintered body layer is preferably longer than the length L1 of the first sintered body layer 6 when viewed in a vertical cross section including the longitudinal direction X of the heat pipe 1. In this case, the second sintered body layer 7 extends continuously from the inner peripheral surface 6a of the first sintered body layer 6 in the evaporation section 3 to the inner peripheral surface 5a of the intermediate section 5. As a result, the liquid phase working fluid F sucked up by the second sintered body layer 7 at the inner peripheral surface 5a of the intermediate section 5 is L is smoothly supplied to the inner peripheral surface 6a of the first sintered body layer 6 through the voids formed inside the second sintered body layer 7, so that the liquid phase working fluid F L In addition, the liquid phase working fluid F L flows from the inner circumferential surface 5a of the intermediate portion 5 toward the tip of the evaporator portion 3 along the longitudinal direction X of the container through the gaps formed inside the second sintered body layer 7, so that the liquid phase working fluid F L and the gas-phase working fluid F passing through the internal space S g The working fluid F in the liquid phase is reduced in contact with the inner circumferential surface 6a of the first sintered body layer 6 in the evaporation section 3, and the working fluid F in the liquid phase is allowed to flow over a wider area of ​​the inner circumferential surface 6a of the first sintered body layer 6 in the evaporation section 3. L can be supplied.

[0032] Here, when viewed from a longitudinal cross section including the longitudinal direction X of the heat pipe 1, the flow of the working fluid F inside the second sintered body layer 7 is as follows: the working fluid F in the liquid phase is sucked up by the inner circumferential surface 5a of the intermediate portion 5. L The flow of the working fluid F in the gas phase generated mainly in the first sintered body layer 6 toward the tip of the evaporator 3 along the longitudinal direction X of the container. g The main flow is toward the internal space S.

[0033] In particular, it is preferable that the second sintered body layer 7 terminates at any position in the intermediate portion 5. In this case, the second sintered body layer 7 extends so as to contact both the inner peripheral surface 6a of the first sintered body layer 6 and the inner peripheral surface 5a of the intermediate portion 5. In addition, the second sintered body layer 7 has both an outer peripheral surface 7b located on the inner peripheral surface 6a of the first sintered body layer 6 and an outer peripheral surface 7b' located on the inner peripheral surface 5a of the intermediate portion 5 of the container 2. On the other hand, it is preferable that the second sintered body layer 7 does not contact the condensation portion 4 from the viewpoint of lowering the temperature of the condensation portion 4 and promoting condensation of the working fluid F.

[0034] Here, the liquid-phase working fluid F that has undergone a phase change in the condenser section 4 L It is preferable that the working fluid F flows toward the evaporation section 3 by capillary force through the internal voids of the second sintered body layer 7 located in the intermediate section 5, and flows from the second sintered body layer 7 toward the first sintered body layer 6 through the contact interface between the outer peripheral surface 7b of the second sintered body layer 7 and the inner peripheral surface 6a of the first sintered body layer 6. By configuring the second sintered body layer 7 in this way, the working fluid F in the liquid phase is L is transported from the inner peripheral surface 5a of the intermediate portion 5 along the second sintered body layer 7 extending in the longitudinal direction X of the container 2 to the portion in contact with the first sintered body layer 6, and is evaporated from a wider range of the first sintered body layer 6. As a result, the liquid phase working fluid F L By efficiently evaporating the heat, the thermal resistance of the heat pipe 1 can be reduced.

[0035] The second sintered body layer 7 is provided on the inner peripheral surface 2a of the container 2 with the liquid phase working fluid F L The liquid flow is configured so that the liquid flow of the working fluid F in the gas phase, which has been phase-changed in the evaporation section 3, flows at least in the internal voids of the second sintered body layer 7. At this time, the second sintered body layer 7 is configured so that the liquid flow of the working fluid F in the gas phase, which has been phase-changed in the evaporation section 3, flows at the position of the intermediate section 5. g The vapor flow of the liquid phase working fluid F that has undergone a phase change in the condenser section 4. L It is preferable that the second sintered body layer 7 is configured to be substantially isolated from the liquid flow of the liquid phase working fluid F passing through the inside of the second sintered body layer 7. L and the gas-phase working fluid F passing through the internal space S g The working fluid F in the gas phase in the evaporation section 3 and the intermediate section 5 due to contact with g This can make it difficult for unintended condensation to occur.

[0036] The second sintered layer 7 is made of a sintered body of a second copper powder, which is a porous material and has a larger average particle size than the first copper powder. As a result, the second sintered layer 7 contains a liquid phase working fluid F L As a result, pores are formed through which the liquid phase working fluid F can pass. L can be transported from the inner peripheral surface 5a of the intermediate portion 5 to the inner peripheral surface 6a of the first sintered body layer 6. In addition, by forming the second sintered body layer 7 from a sintered body of copper powder, it is possible to improve wettability with the working fluid F and increase thermal conductivity. Therefore, the second sintered body layer 7 has high thermal conductivity and can easily wet the liquid phase working fluid F. L This allows the first sintered body layer 6, from which the organic solvent evaporates, to exhibit resistance to dry-out.

[0037] Here, the average particle size (average primary particle size) of the second copper powder constituting the second sintered body layer 7 is not particularly limited, but may be, for example, in the range of 100 μm to 500 μm. The ratio of the average particle size of the second copper powder to the average particle size of the first copper powder is not particularly limited, but may be, for example, in the range of 2 to 5. On the other hand, the thickness of the second sintered body layer 7 is not particularly limited, but may be, for example, in the range of 0.3 mm to 5 mm.

[0038] The second sintered body layer 7 preferably has an area ratio of 50% to 90% of the total area of ​​the first sintered body layer 6 and the second sintered body layer 7 when the evaporation section 3 is viewed in a cross section perpendicular to the longitudinal direction X of the heat pipe 1. By increasing the area ratio of the second sintered body layer 7 in this way, the liquid phase working fluid F passing through the inside of the second sintered body layer 7 can be reduced. L Since the flow rate of the working fluid F increases, the efficiency of the reflux of the working fluid F can be further increased.

[0039] [About the working principle of heat pipes] Next, the operation principle of the heat pipe 1 will be described using the heat pipe 1 of the first embodiment shown in Figures 1 and 2. Here, the heat pipe 1 is filled with a liquid-phase working fluid F before operation. Lis sealed in the internal space S.

[0040] First, the liquid phase working fluid F L is supplied to the part of the inner circumferential surface 2a of the container 2 that is in contact with the second sintered body layer 7. L The supplying means is not particularly limited. For example, the second sintered body layer 7 may be supplied with the liquid phase working fluid F L By using the capillary force that occurs when the second sintered body layer 7 comes into contact with the liquid phase working fluid F L Since it is possible to supply the liquid, the occurrence of dry out can be suppressed.

[0041] The liquid phase working fluid F is supplied to the part of the inner circumferential surface 2a of the container 2 that is in contact with the second sintered body layer 7. L At least a part of the working fluid F in the liquid phase is absorbed into the second sintered body layer 7 and flows into the internal voids of the second sintered body layer 7. In particular, when a plurality of grooves 8 are formed on the inner peripheral surface 2a of the container 2 as described later, the working fluid F in the liquid phase is absorbed into the second sintered body layer 7 and flows into the internal voids of the second sintered body layer 7. L The liquid flow may be divided into a path passing through the plurality of grooves 8 and a path passing through the internal voids of the second sintered body layer 7.

[0042] The liquid phase working fluid F absorbed in the second sintered body layer 7 L flows along the longitudinal direction X due to the capillary force of the second sintered body layer 7, and is absorbed by the first sintered body layer 6 in a wide area where the second sintered body layer 7 and the first sintered body layer 6 contact each other. On the other hand, the working fluid F that flows through the grooves 8 without being absorbed by the second sintered body layer 7 L is absorbed by the first sintered body layer 6 or the second sintered body layer 7 in the area where the groove 8 and the first sintered body layer 6 or the second sintered body layer 7 are close to each other.

[0043] Here, when the evaporator 3 of the heat pipe 1 receives heat from the heat generating element 9 thermally connected thereto, the liquid phase working fluid F L On the surface of the first sintered body layer 6 to which the working fluid F in the liquid phase is supplied, L is evaporated to gas phase working fluid F gIn particular, in the heat pipe 1, the liquid phase working fluid F is absorbed from the heating element 9 as latent heat of vaporization by changing its phase to the liquid phase working fluid F in the portion of the container 2 facing the heating element 9 and in the vicinity thereof. L Let F be the gas phase working fluid. g Since the phase change can be efficiently performed, the thermal resistance of the heat pipe 1 can be significantly reduced.

[0044] The vapor phase working fluid F that absorbs heat in the evaporation section 3 g flows from the evaporator (heat receiving section) 3 to the condenser (heat dissipating section) 4 along the longitudinal direction X of the container 2 through the vapor flow path, which is the internal space S of the container 2, and the heat received from the heating element 9 is transported from the evaporator 3 to the condenser 4 through the intermediate section 5. At this time, the gas-phase working fluid F transported from the evaporator 3 to the condenser 4 through the intermediate section 5 is g is the liquid phase working fluid F passing through the inside of the second sintered body layer 7. L Since it becomes difficult for the gas phase working fluid F to come into contact with g This makes it possible to prevent the circulating flow of the working fluid F from being disturbed by a counter flow of the working fluid F. Therefore, the heat pipe 1 can achieve excellent heat transport properties.

[0045] Then, the gas phase working fluid F is transported to the condensation section 4. g is changed into a liquid phase in the condenser 4 by a heat exchanger (not shown). At this time, the heat of the transported heating element 9 is released to the outside of the heat pipe 1 as latent heat of condensation. Then, the liquid-phase working fluid F which has released heat and changed into a liquid phase in the condenser 4 is L is supplied to the inner circumferential surface 2a of the container 2 along the longitudinal direction X to a portion of the inner circumferential surface 2a of the container 2 that is in contact with the second sintered body layer 7, thereby forming a circulating flow of the working fluid between the evaporator section 3 and the condenser section 4.

[0046] <Second embodiment> FIG. 3 is a diagram showing the internal structure of a heat pipe according to a second embodiment, in which FIG. 3(a) is a vertical cross-sectional view, and FIG. 3(b) is a cross-sectional view of FIG. 3(a). A -II AThe cross-sectional view when cut along the line in Fig. 3(c) is II in Fig. 3(a). B -II B 3 is a cross-sectional view taken along the line 3. Note that the components shown in Fig. 3 that are the same as those of the heat pipe 1 shown in Fig. 1 are denoted by the same reference numerals.

[0047] In the heat pipe 1 shown in the first embodiment, the inner circumferential surface 2a of the container 2 is configured as a smooth surface, but the present invention is not limited to this. For example, as in the heat pipe 1A shown in FIG. 3, a plurality of grooves 8 extending along the longitudinal direction L of the container 2A may be formed on the inner circumferential surface 2a of the container 2A. By providing such grooves 8, the liquid phase working fluid F inside the heat pipe 1 can be prevented from flowing through the container 2A. L When transporting the liquid phase working fluid F L Capillary force can be exerted so that the liquid phase working fluid F moves along the groove 8 and the second sintered body layer 7 on the inner circumferential surface 2a of the container 2A. L The heat pipe can promote the transport of the condenser gas and can have reverse operation. Here, reverse operation refers to the ability to function as a heat pipe even when the position of the evaporator section 3 is higher than the position of the condenser section 4.

[0048] These grooves 8 preferably extend in the longitudinal direction X on the inner circumferential surface 2a from the condenser 4 to the portion where the second sintered body layer 7 is located, and more preferably the grooves 8 extend continuously from the condenser 4 to the evaporator 3. This allows the liquid phase working fluid F to flow from the condenser 4 to the portion where the second sintered body layer 7 is located. L Since the transport of the working fluid F in the liquid phase is promoted, the working fluid F in the liquid phase is transported to the first sintered body layer 6 in the evaporation section 3 through the second sintered body layer 7. L In particular, by providing the grooves 8 that are continuous from the condenser section 4 to the evaporator section 3, the transport of the liquid phase working fluid F L can be supplied to the first sintered body layer 6 located in the evaporation section 3 through both the path passing through the inside of the second sintered body layer 7 and the path passing through the grooves 8.

[0049] The container 2A having the groove 8 may be a grooved pipe in which a groove 8 extending in the longitudinal direction X of the container 2A is formed on the inner peripheral surface 2a of the container 2A. In particular, by forming the container 2A from a grooved pipe, the liquid phase working fluid F can be circulated over the entire length of the container 2A. L When the heat pipe 1A is installed in the top heat position, that is, when the liquid phase working fluid F L Even if the evaporator section 3 downstream of the condenser section 4 and the intermediate section 5 are installed above the condenser section 4 and the intermediate section 5, the liquid phase working fluid F L This makes it easier to transport the items.

[0050] The opening width of these grooves 8 is not particularly limited, but the liquid phase working fluid F L From the viewpoint of promoting the transport of the particles, the thickness may be, for example, 0.1 mm to 1 mm.

[0051] It is preferable that the first sintered body layer 6A of the heat pipe 1A is also filled and formed in the grooves 8 located in a specific region on the inner circumferential surface 2a of the container. In other words, it is preferable that the first sintered body layer 6A is formed so as to include the container 2A side with respect to the imaginary inner circumferential surface 3b, which is assumed to be a case in which the grooves 8 are not formed in the evaporation section 3 of the container. More preferably, the first sintered body layer 6A fills a part or the whole of the grooves 8 in the longitudinal direction X. In particular, it is preferable that the first sintered body layer 6A is formed so as to contact the bottom of the grooves 8, as shown in FIG. 3(b). This allows the liquid-phase working fluid F transported along the grooves 8 to flow smoothly. L However, when the working fluid F comes into contact with the first sintered body layer 6A, it is easily sucked up by the first sintered body layer 6A. L This can further promote the evaporation of the volatile organic compound.

[0052] Here, as shown in FIG. 3(a), the inner peripheral surface of the first sintered body layer 6A is preferably configured to be located closer to the central axis position M of the internal space S of the container 2A than the boundary surface position N where the part of the second sintered body layer 7A and the part of the inner peripheral surface 2a of the container 2A contact, which is located in the intermediate portion 5. This allows the liquid phase working fluid F flowing through the second sintered body layer 7A to flow closer to the central axis position M of the internal space S of the container 2A. L At least a part of the flow of the liquid phase working fluid F from the second sintered body layer 7A to the first sintered body layer 6A hits the first sintered body layer 6A. L This can promote the distribution of

[0053] The first sintered body layer 6A may also be configured so that a space of the groove 8 exists between the inner peripheral surface 2a of the container 2A and the outer peripheral surface 6b of the first sintered body layer 6A. This allows the liquid-phase working fluid F that has undergone a phase change in the condenser 4 to flow through the groove 8. L The liquid phase working fluid F can be more quickly moved through the grooves 8 to the position of the evaporation section 3 where the outer peripheral surface of the first sintered body layer 6A is present. As a result, the liquid phase working fluid F can be more quickly moved from the condensation section 4 to the evaporation section 3. L This can further promote the circulation of waste.

[0054] The second sintered layer 7A of the heat pipe 1A is a gas-phase working fluid F g The vapor flow of the liquid phase working fluid F that has undergone a phase change in the condenser section 4. L and substantially isolates the liquid flow of the working fluid F L It is preferable that the liquid flow is divided into a path passing through the multiple grooves 8 and a path passing through the internal voids of the second sintered body layer 7A. This allows a larger amount of liquid phase working fluid F to flow in the area where the second sintered body layer 7A and the grooves 8 are arranged. L Since the liquid phase working fluid F in this part can flow, L In addition, in the portion where the path passing through the plurality of grooves 8 and the path passing through the internal voids of the second sintered body layer 7 are formed in parallel, the liquid phase working fluid F L Since the liquid phase working fluid F in the intermediate section 5 and the evaporation section 3 is sucked up more strongly, LThis increases the flow rate of the heat pipe 1, thereby further improving the heat transport characteristics of the heat pipe 1.

[0055] The average particle size (average primary particle size) of the second copper powder constituting the second sintered body layer 7A is not particularly limited, and may be in the range of 100 μm to 500 μm, similar to the above-mentioned heat pipe 1. On the other hand, the average particle size (average primary particle size) of the second copper powder constituting the second sintered body layer 7A is set to be smaller than the average particle size of the liquid-phase working fluid F formed in the grooves 8. L From the viewpoint of not blocking the flow path of the groove 8, it is preferable that the groove width be larger than that of the groove 8.

[0056] The second sintered body layer 7A is a layer in which the liquid-phase working fluid F L From the viewpoint of not blocking the flow path of the second sintered body layer 7A, it is preferable not to fill the grooves 8. Here, means for forming the second sintered body layer 7A so as not to fill the grooves 8 include a means for using, as the second copper powder, a copper powder having a larger average particle size than the above-mentioned first copper powder, and a means for sintering the second copper powder by reducing the force applied to the copper powder when the second copper powder is loaded into the container 2.

[0057] <Other embodiments> In the above embodiment, the container 2 extends toward one side of the evaporator 3 and has one condenser section 4 and one intermediate section 5, but the present invention is not limited to this configuration. For example, the container 2 may extend from the evaporator 3 in multiple directions, and the condenser sections 4 and intermediate sections 5 may be provided in multiple locations. In the heat pipe 1, the container 2 extends from the evaporator 3 in multiple directions to condense the liquid-phase working fluid F L Even if the flow rate of the condenser 1 is increased, the heat received from the heating element 9 as the latent heat of vaporization can be efficiently transferred to a plurality of condensation sections.

[0058] <Heat pipe manufacturing method> A specific example of the method for manufacturing a heat pipe will be described below.

[0059] The shape of the container 2, such as a tubular vessel, used in the heat pipe 1 can be appropriately selected from pipe, plate, foil, etc., according to the shape of the heat pipe 1. Dirt adhering to the surface of the container 2 may lead to a decrease in the heat transfer ability of the heat pipe, so it is preferable to clean it. Cleaning can be performed by a general method, such as solvent degreasing, electrolytic degreasing, etching, oxidation treatment, etc.

[0060] A core rod (e.g., a stainless steel core rod) having a shape that will be the mold for the first sintered body layer 6 is inserted into the center of the interior of the container 2, and then a first copper powder, which is the raw material for the first sintered body layer 6, is loaded into the gap formed between the inner circumferential surface 2a of the container 2 and the outer surface of the core rod, and the loaded first copper powder is sintered to form the first sintered body layer 6. The core rod is pulled out and removed from the container 2 on which the first sintered body layer 6 has been formed. Here, from the viewpoint of providing the first sintered body layer 6 only in a specific region on the inner circumferential surface 2a of the container 2, the formed first sintered body layer 6 may be subjected to cutting or the like.

[0061] Next, a core rod (e.g., a stainless steel core rod) having a shape that will be the mold for the second sintered body layer 7 is inserted into the center of the interior of the container 2, and second copper powder, which is the raw material for the second sintered body layer 7, is loaded into the gap formed between the inner surface of the container 2 and the outer surface of the core rod, and the loaded second copper powder is sintered to form the second sintered body layer 7. The core rod is pulled out and removed from the container 2 on which the second sintered body layer 7 has been formed.

[0062] Here, the sintering of the first and second copper powders, which are the raw materials of the first sintered body layer 6 and the second sintered body layer 7, may be performed under conditions that are generally used, and are not particularly limited. One example of the sintering conditions is to perform a heat treatment in an atmosphere of a reducing gas, such as hydrogen gas or a mixed gas containing hydrogen gas and an inert gas (N2, Ar, He, etc.).

[0063] After the first sintered body layer 6 and the second sintered body layer 7 are formed in the container 2, only one end of the container 2 is sealed except for the other end, which is the inlet, and the working fluid F is poured in through the inlet. After pouring in the working fluid F, the inside of the container 2 is degassed by heating, vacuum degassing, or other degassing process to reduce the pressure. The inlet is then sealed to produce the heat pipe 1.

[0064] The sealing method is not particularly limited, and examples thereof include TIG welding, resistance welding, pressure welding, and soldering. The first sealing (sealing only the other end) is a process performed to seal the area other than the area from which the internal gas escapes during the subsequent degassing, and the second sealing (sealing the injection port) is a process performed to seal the area from which the internal gas escapes during degassing.

[0065] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. EXAMPLES

[0066] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0067] (Example of the present invention) The heat pipe 1B of the present invention is an example of a cylindrical heat pipe 1 having an internal structure shown in FIG. 1. A cylindrical tubular container having a length of 400 mm along the longitudinal direction X and a diameter (inner diameter) of 7 mm was used as the container 2. A stainless steel core rod having a shape to be a mold for the first sintered body layer 6B was inserted and arranged at the center of the inside of the container 2, and then copper powder (first copper powder) having an average particle size (average primary particle size) of 100 μm, which is the raw material for the first sintered body layer 6B, was filled in the gap formed between the inner surface of the groove tube and the outer surface of the core rod. Then, the container 2 filled with the first copper powder was subjected to a heat treatment under a reducing gas atmosphere to sinter the copper powder, and the core rod was pulled out and removed from the container 2. As a result, a first sintered body layer 6B made of a copper sintered body having a thickness of 0.5 mm was formed in a specific region on the inner circumferential surface 2a of the container 2, more specifically, in a region having an area ratio of 67% of the entire area of ​​the inner circumferential surface 2a of the portion that becomes the evaporation section 3, including the entire region of the inner circumferential surface 2a that constitutes the portion facing the heating element 9. Here, when the portion that becomes the evaporation section 3 of the heat pipe 1B is viewed in a cross section perpendicular to the longitudinal direction X, the length of the region that constitutes the portion of the inner circumferential surface 2a of the container 2 that faces the heating element 9 is 50% of the entire length of the inner circumferential surface 2a, and the region where the first sintered body layer 6B is formed is arranged in the region of the inner circumferential surface 2a that constitutes the portion facing the heating element 9 and the region on the inner circumferential surface 2a adjacent to both sides thereof, so that the sizes of the regions on both sides are equal. In addition, the region of the inner circumferential surface 2a of the container 2 that constitutes the portion facing the heating element 9 is provided in a range from 15 mm to 55 mm from the tip of the container 2 on the evaporator 3 side when viewed in a vertical cross section including the longitudinal direction X of the heat pipe 1B, and the range from the tip of the evaporator 3 side to the position of 55 mm is defined as the evaporator 3. Therefore, the longitudinal dimension L0 of the evaporator 3 is 55 mm. In addition, the first sintered body layer 6B is provided in a range from the tip of the evaporator 3 side to the position of 60 mm when viewed in a vertical cross section including the longitudinal direction X of the heat pipe 1B. Therefore, the arrangement length L1 of the first sintered body layer 6B along the longitudinal direction X is 60 mm.

[0068] Next, a stainless steel core rod having a shape to be the mold for the second sintered layer 7 was inserted into the center of the container 2, and copper powder (second copper powder) having an average particle size (average primary particle size) of 200 μm, which is the raw material for the second sintered layer 7, was filled into the gap formed between the inner surface of the groove tube and the outer surface of the core rod. Then, the container 2 filled with the second copper powder was subjected to a heat treatment in a reducing gas atmosphere to sinter the copper powder, and the core rod was pulled out and removed from the container 2. As a result, from the tip of the container 2 on the evaporation section 3 side to the intermediate section 5, as shown in Figure 4 (a), with the first sintered body layer 6B partially interposed between the inner surface 2a of the container 2 and the second sintered body layer 7 made of a copper sintered body was formed on the entire inner surface 2a of the container 2 when viewed in a cross section perpendicular to the longitudinal direction X, with the length along the longitudinal direction X being 250 mm and the inner diameter of the inner surface being 5 mm (the thickness of the part where the first sintered body layer 6B is formed is 0.5 mm, and the thickness of the part where the first sintered body layer 6B is not formed is 1.0 mm).

[0069] After the first sintered body layer 6 and the second sintered body layer 7 were formed, only one end of the container 2 was sealed except for the inlet, and water, which is the liquid phase working fluid F(L), was poured in through the inlet. Next, the inside of the container 2 was degassed to create a reduced pressure state, and then the inlet was sealed to produce the heat pipe 1.

[0070] (Comparative Example) 4(b), the heat pipe 10 of the comparative example was formed by forming a first sintered body layer 6C made of a copper sintered body with a length of 60 mm along the longitudinal direction X and a thickness of 0.5 mm on the entire inner peripheral surface 2a of the container 2. Other than that, the heat pipe 10 was produced to have the same configuration as the heat pipe of the present invention.

[0071] Here, Figure 4 is a cross-sectional view showing the internal structure of heat pipes of an example of the present invention and a comparative example, where Figure 4(a) is a cross-sectional view of heat pipe 1 of an example of the present invention, and Figure 4(b) is a cross-sectional view of heat pipe 10 of the comparative example.

[0072] (Performance evaluation) The performance of the heat pipe was evaluated under the following conditions: 1. A heater block (heat output 50W to 250W) was attached as a heating element to the outer surface of the evaporation section (heat receiving section), which is one end of the heat pipe. 2. A heat exchange means was attached to the condensation section (heat dissipation section), which is the other end of the heat pipe. 3. The intermediate section between the evaporation section and the condensation section was insulated by installing insulation material. 4. With the device installed horizontally, the heat input to the evaporation section was gradually increased from 50 W, and the magnitude of the heat input when the difference between the temperature of the heating element and the temperature of the condensation section was minimized was measured, and this measured heat input was taken as the maximum heat transport rate Qmax (W). 5. The difference between the temperature of the heating element and the temperature of the condensation section was measured and divided by the amount of heat input to obtain the thermal resistance (℃ / W).

[0073] Among these, the results of the maximum heat transport quantity Qmax were expressed as a relative value when the comparative example in which the first sintered layer 6 was formed on the entire surface of the inner peripheral surface 2a of the container 2 was set as the reference (index ratio 100). The results are shown in the "Relative value of maximum heat transport quantity" column of Table 1.

[0074] [Table 1]

[0075] As a result, the heat pipe 1 of the present invention had a maximum heat transport capacity Qmax of 128 relative to the comparative example in which the first sintered layer 6 was formed over the entire inner surface 2a of the container 2 (index ratio 100).

[0076] Therefore, since the heat pipe 1 of the example of the present invention had a larger relative value of the maximum heat transport amount Qmax than the heat pipe 10 of the comparative example, it was found to have high heat transport properties. [Explanation of symbols]

[0077] 1, 1A heat pipe 2. 2A Container 2a Inner surface of container 3 Evaporation section 3a Inner surface of the evaporation section of the container 3b Virtual inner surface of the evaporation section of the container 4 Condenser 5. Middle section 5a Inner surface of the middle part of the container 6, 6A First sintered layer 6a: inner peripheral surface of first sintered body layer 6b Outer circumferential surface of the first sintered body layer 7, 7A Second sintered layer 7b: an outer peripheral surface of the second sintered body layer located on the inner peripheral surface of the first sintered body layer 7b' The outer peripheral surface of the second sintered body layer located on the inner peripheral surface of the middle part of the container 8 grooves 9 Heating element 10 Comparative Example Heat Pipe F Working fluid F L Liquid phase working fluid F g Gas phase working fluid L0 Longitudinal dimension of evaporation section L1: Length of the first sintered layer L2: Length of the second sintered layer M Central axis position of the container's internal space N: The boundary surface position where the second sintered body layer and the inner peripheral surface of the container are in contact with each other, located in the middle part. S interior space X: Longitudinal direction of container Y Container thickness direction Z: Container depth

Claims

1. A container having an internal space in which a working fluid is sealed, an evaporation section that evaporates the liquid-phase working fluid and changes the phase of the working fluid to a gas-phase working fluid; a condensation section disposed at a position separated from the evaporation section and configured to condense the gas phase working fluid to change the phase of the working fluid into a liquid phase working fluid; an intermediate section located between the evaporator section and the condenser section; In a heat pipe comprising: When viewed in a cross section of the heat pipe in the evaporation section, a first sintered body layer formed in a specific region on an inner circumferential surface of the container, the first sintered body layer being made of a sintered body of a first copper powder; a second sintered body layer formed in an annular shape over the entire inner circumferential surface of the container, the second sintered body layer being made of a sintered body of a second copper powder having an average particle size larger than that of the first copper powder, the second sintered body layer being interposed between the first sintered body layer and the inner circumferential surface of the container; A heat pipe having

2. When viewed in a longitudinal section including the longitudinal direction of the heat pipe, The length of the first sintered body layer is longer than the longitudinal dimension of the evaporation section, and The heat pipe according to claim 1 , wherein an arrangement length of the second sintered body layer is longer than an arrangement length of the first sintered body layer.

3. The heat pipe according to claim 2 , wherein the second sintered layer terminates at a position anywhere in the intermediate portion.

4. The heat pipe described in claim 3, wherein the liquid phase working fluid that has undergone a phase change in the condensation section flows toward the evaporation section by capillary force through internal voids of the second sintered body layer located in the middle section, and flows from the second sintered body layer toward the first sintered body layer through the contact interface between the outer circumferential surface of the second sintered body layer and the inner circumferential surface of the first sintered body layer.

5. The heat pipe according to claim 1 , wherein the specific region includes a region of an inner circumferential surface of the container that constitutes a portion facing a heat generating element.

6. The heat pipe according to claim 1 , wherein a plurality of grooves are formed on an inner peripheral surface of the container, the grooves extending along a longitudinal direction of the container.

7. The heat pipe according to claim 6 , wherein the first sintered layer is also filled in the grooves located in the specific region.

8. 7. The heat pipe of claim 6, wherein the second sintered body layer substantially isolates a vapor flow of the gas-phase working fluid that has undergone a phase change in the evaporator section from a liquid flow of the liquid-phase working fluid that has undergone a phase change in the condenser section, and the liquid flow is divided into a path that passes through the multiple grooves and a path that passes through internal voids in the second sintered body layer.

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