Heat pipe

Abstract

The invention provides a heat pipe which can improve backflow efficiency of working fluid, thereby having excellent heat transfer characteristics. A heat pipe (1), in a sealed container (2) having an internal space (S) in which a working fluid (F) has been sealed, is provided with: an evaporation unit (3) that evaporates a liquid-phase working fluid (FL) and changes the phase into a gas-phase working fluid (Fg); a condensation unit (4) which is disposed at a position separated from the evaporation unit (3) and which condenses the working fluid (Fg) in the gas phase and changes the phase of the working fluid (Fg) into the working fluid (FL) in the liquid phase; and an intermediate part 5 located between the evaporation part 3 and the condensation part 4. The heat pipe (1), when viewed from the cross-section of the evaporator (3), has: a first sintered body layer (6) that is formed from a sintered body of a first copper powder and that is formed in a specific region on the inner peripheral surface (2a) of the sealed container (2); and a second sintered body layer (7) comprising a sintered body of a second copper powder having a larger average particle diameter than that of the first copper powder and formed in a ring shape over the entire inner peripheral surface (2a) of the sealed container (2) in a state in which the first sintered body layer (6) is interposed between the second sintered body layer (7) and the inner peripheral surface (2a) of the sealed container (2).

Description

Technical Field

[0001] The invention relates to a heat pipe having heat transfer properties. Background Art

[0002] In recent years, electronic components such as semiconductor elements installed in electrical and electronic devices such as notebook computers, digital cameras, and mobile phones have tended to generate more heat due to high-density assembly with high functionality, so it is important to adopt a structure that can be cooled efficiently. As a means for cooling electronic components, for example, a method of cooling using a heat pipe can be cited.

[0003] Here, generally speaking, the heat pipe has a tubular container (sealed container) having an internal space in which a working fluid has been sealed. The tubular container has an evaporation portion at one end side portion that causes the liquid phase working fluid to evaporate and change phase to the gas phase working fluid, and has a condensation portion at the other end side portion that causes the gas phase working fluid to condense and change phase to the liquid phase working fluid. The working fluid that changes phase from the liquid phase to the gas phase in the evaporation portion flows from the evaporation portion to the condensation portion, and the working fluid that changes phase from the gas phase to the liquid phase in the condensation portion flows from the condensation portion to the evaporation portion. In this way, a circulating flow generated by the reflux of the working fluid is formed between the evaporation portion and the condensation portion in the tubular container, thereby performing heat transfer between the evaporation portion and the condensation portion in the tubular container.

[0004] As a previous heat pipe, for example, Patent Document 1 describes a heat pipe comprising a heat pipe body, a porous metal layer, and a working fluid, wherein the heat pipe body has a closed hollow portion, the porous metal layer is arranged in a manner connected to the inner peripheral surface of the heat pipe body, and the working fluid is sealed in the heat pipe body, wherein the porous metal layer has a first porous portion divided in the circumferential direction and a second porous portion having a smaller porosity than the first porous portion. This heat pipe is constructed so that the liquid working fluid is moved mainly by the first porous portion, and heat exchange between the heat pipe body and the working fluid is mainly achieved by the second porous portion.

[0005] [Prior Technical Literature]

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Publication No. 2003-148886 Summary of the invention

[0008] [Problems that the invention aims to solve]

[0009] The heat pipe described in Patent Document 1 changes the working fluid from a liquid phase to a gas phase in the second porous portion. However, in order to cope with the further increase in the heat generation of the electronic device, more working fluid must be efficiently refluxed. Here, if the thickness of the second porous portion is increased, the reflux efficiency of the working fluid may be improved, but since the hollow portion for the gas phase working fluid to flow becomes narrower, the heat transfer characteristics of the heat pipe are reduced.

[0010] An object of the present invention is to provide a heat pipe capable of improving the reflux efficiency of a working fluid, thereby having excellent heat transfer characteristics.

[0011] [Technical means to solve the problem]

[0012] In order to achieve the above objectives, the key structures of the present invention are as described below.

[0013] (1) A heat pipe, in a sealed container having an internal space in which a working fluid is sealed, comprising: an evaporation portion for evaporating a liquid working fluid and causing a phase change to a gaseous working fluid; a condensation portion disposed at a position separated from the evaporation portion and causing a phase change to a liquid working fluid by condensing the gaseous working fluid; and an intermediate portion located between the evaporation portion and the condensation portion; wherein the heat pipe, as viewed from a cross section of the heat pipe in the evaporator, comprises: a first sintered body layer composed of a sintered body of a first copper powder and formed in a specific area on the inner peripheral surface of the sealed container; and a second sintered body layer composed of a sintered body of a second copper powder, the average particle size of the second copper powder being larger than the average particle size of the first copper powder, and the first sintered body layer being interposed between the second sintered body layer and the inner peripheral surface of the sealed container, and extending over the entire inner peripheral surface of the sealed container to form a ring shape.

[0014] (2) A heat pipe as described in (1) above, wherein, when observed from a longitudinal section including the long side direction of the heat pipe, the arrangement length of the first sintered body layer is longer than the long side dimension of the evaporation portion, and the arrangement length of the second sintered body layer is longer than the arrangement length of the first sintered body layer.

[0015] (3) The heat pipe according to the above (2), wherein the second sintered body layer ends at any position of the intermediate portion.

[0016] (4) A heat pipe as described in (3) above, wherein the working fluid that changes phase into a liquid phase in the condensation section is configured to flow toward the evaporation section by means of a capillary force generated through internal voids of the second sintered body layer located in the middle section, and to flow from the second sintered body layer toward the first sintered body layer through a contact interface between an outer peripheral surface of the second sintered body layer and an inner peripheral surface of the first sintered body layer.

[0017] (5) The heat pipe according to any one of (1) to (4) above, wherein the specific region includes a region constituting an inner peripheral surface of a portion of the sealed container that faces the heat generating element.

[0018] (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 closed container are formed on the inner peripheral surface of the closed container.

[0019] (7) In the heat pipe described in (6) above, the first sintered body layer is also formed to fill the groove located in the specific region.

[0020] (8) A heat pipe as described in (6) or (7) above, wherein the second sintered body layer is constructed to substantially isolate the vapor flow of the working fluid that changes phase into a gas phase in the evaporation portion from the liquid flow of the working fluid that changes phase into a liquid phase in the condensation portion, and the liquid flow is divided into a path passing through the plurality of grooves and a path passing through internal voids of the second sintered body layer.

[0021] [effect]

[0022] According to the present invention, a heat pipe can be provided which can improve the reflux efficiency of a working fluid and thus has more excellent heat transfer characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a diagram showing the internal structure of a heat pipe according to the first embodiment. Figure 1 (a) is a longitudinal section view, Figure 1 (b) is along Figure 1 (a)I A -I A Cross-sectional view when the wire is cut, Figure 1 (c) is along Figure 1 (a)I B -I B Cross-sectional view when the wire is cut.

[0024] Figure 2 It is about Figure 1 A cross-sectional view of the flow of working fluid generated inside a heat pipe in operation.

[0025] Figure 3 is a diagram showing the internal structure of a heat pipe according to a second embodiment. Figure 3 (a) is a longitudinal section view, Figure 3 (b) is along Figure 3 (a)II A -II A Cross-sectional view when the wire is cut, Figure 3 (c) is along Figure 3(a)II B -II B Cross-sectional view when the wire is cut.

[0026] Figure 4 is a cross-sectional view showing the internal structure of the heat pipe of the present invention example and the comparative example, Figure 4 (a) is a cross-sectional view of a heat pipe according to an example of the present invention, Figure 4 (b) is a cross-sectional view of a heat pipe of a comparative example. DETAILED DESCRIPTION

[0027] Next, heat pipes according to several embodiments of the present invention will be described below.

[0028] <First Embodiment>

[0029] Figure 1 is a diagram showing the internal structure of a heat pipe according to the first embodiment. Figure 1 (a) is a longitudinal section view, Figure 1 (b) is along Figure 1 (a)I A -I A Cross-sectional view when the wire is cut, Figure 1 (c) is along Figure 1 (a)I B -I B Cross-sectional view when the line is cut. On the other hand, Figure 2 It is about Figure 1 A cross-sectional view of the flow of working fluid generated inside a heat pipe in operation.

[0030] The heat pipe 1 includes a sealed container 2 having an internal space S in which a working fluid F is sealed, and an evaporation portion 3 for evaporating the working fluid F in a liquid phase. L The working fluid F that evaporates and changes phase into a gas phase g ; The condensation section 4 is disposed at a position separated from the evaporation section 3, and the gas phase working fluid F g The working fluid F that condenses and changes phase into a liquid phase L and, the middle portion 5 is located between the evaporation portion 3 and the condensation portion 4. The heat pipe 1, as viewed from the cross section in the evaporator 3, comprises: a first sintered body layer 6, which is composed of a sintered body of a first copper powder and is formed in a specific area on the inner peripheral surface 2a of the sealed container 2; and, a second sintered body layer 7, which is composed of a sintered body of a second copper powder, the average particle size of the second copper powder being larger than the average particle size of the first copper powder, and which is spread over the entire inner peripheral surface 2a of the sealed container 2 to form a ring shape in a state where the first sintered body layer 6 is interposed between the second sintered body layer 7 and the inner peripheral surface 2a of the sealed container 2.

[0031] The heat pipe 1 has a second sintered body layer 7 formed of a second copper powder having a larger average particle size than the first copper powder, which is laminated on the inner peripheral surface 6a of the first sintered body layer 6 formed of the first copper powder. L The heat is supplied to the first sintered body layer 6 through the voids in the second sintered body layer 7, and is transferred to the liquid working fluid F reaching the inner peripheral surface 6a of the first sintered body layer 6 and the voids formed therein. L , so that in the first sintered body layer 6, the liquid working fluid F L The working fluid F that evaporates and changes phase into a gas phase g , thereby achieving heat exchange between the portion of the evaporation portion 3 where the first sintered body layer 6 is formed and the working fluid F. Therefore, the heat transferred to the portion of the evaporation portion 3 where the first sintered body layer 6 is formed can be transferred to the working fluid F in the gas phase. g In particular, when the evaporation section 3 is observed from a cross section perpendicular to the longitudinal direction X, the first sintered body layer 6 is formed in a part of the inner peripheral surface 2a of the sealed container 2, that is, in a specific area, and the second sintered body layer 7 is formed in a ring shape over the entire inner peripheral surface 2a of the sealed container 2. As a result, the entire surface of the first sintered body layer 6 becomes a working fluid F in the liquid phase. L The first sintered body layer 6 and the second sintered body layer 7 are covered by the flowing second sintered body layer 7, thereby increasing the contact area between the first sintered body layer 6 and the second sintered body layer 7. L The working fluid F is supplied to a wider range than the inner peripheral surface 6a of the first sintered body layer 6, so the reflux of the working fluid F can be promoted. In conjunction with this, on the inner peripheral surface 2a of the closed container 2, the area of ​​the reflux portion, that is, the area of ​​the second sintered body layer 7, becomes larger relative to the area of ​​the first sintered body layer 6, so the reflux efficiency of the working fluid F can be improved.

[0032] Thus, the heat pipe 1 can efficiently make the liquid working fluid F L Recirculation, so it is possible to provide a heat pipe that can improve the recirculation efficiency of the working fluid and thereby have excellent heat transfer characteristics.

[0033] [Regarding the structure of the sealed container]

[0034] Figure 1 and Figure 2 The heat pipe 1 shown includes a closed container 2 having an internal space S in which a working fluid F is sealed. Figure 1 and Figure 2 In FIG. 1 , a tubular container is shown as an example of the sealed container 2 .

[0035] Here, regarding the extended shape of the sealed container 2 in the long side direction X, except Figure 1In addition to the straight shape shown in (a), there are other shapes with curved portions such as L-shaped or U-shaped, etc., which are not particularly limited. In addition, the outer contour shape of the sealed container 2 when cut in a direction perpendicular to the long side direction X of the sealed container 2 is Figure 1 (b) and Figure 1 In addition to the approximately circular shape shown in (c), there are other shapes such as flat shapes, quadrilateral shapes, etc., which are not particularly limited. The wall thickness of the sealed container 2 is not particularly limited, and for example, it can be in the range of 0.05 mm to 1.0 mm. The outer diameter of the sealed container 2 is not particularly limited, and for example, when the sealed container 2 is Figure 1 (b) and Figure 1 In the case of the approximately circular outer contour shape shown in (c), it is preferably in the range of 5 mm to 20 mm.

[0036] The material of the sealed container 2 is not particularly limited. In particular, when an aqueous liquid is used as the working fluid F, it is preferred to use a metal material from the viewpoint of good wettability with the working fluid F. In particular, from the viewpoint of having excellent thermal conductivity, the sealed container 2 can use, for example, copper, copper alloys, etc. In addition, from the viewpoint of lightweight, the sealed container 2 can use, for example, aluminum, aluminum alloys, etc. In addition, from the viewpoint of having high strength, the sealed container 2 can use, for example, stainless steel, etc. In addition, in addition to this, according to the use conditions, the sealed container 2 can also use, for example, tin, tin alloys, titanium, titanium alloys, nickel, nickel alloys, etc.

[0037] [About the structure of the evaporation section, condensation section and intermediate section]

[0038] The heat pipe 1 is provided with an evaporation section 3 in a sealed container 2 for evaporating a liquid working fluid F. L The working fluid F that evaporates and changes phase into a gas phase g ; The condensation section 4 is disposed at a position separated from the evaporation section 3, and the gas phase working fluid F g The working fluid F that condenses and changes phase into a liquid phase L and the middle portion 5 is located between the evaporation portion 3 and the condensation portion 4. Here, the evaporation portion 3, the condensation portion 4 and the middle portion 5 are as shown in FIG. Figure 1 As shown in (a), they can be respectively provided at a portion along the longitudinal direction X of the closed container 2. Figure 1 The closed container 2 shown in (a) has a structure as follows: an evaporation section 3 is provided at one end side portion, a condensation section 4 is provided at the other end side portion, an intermediate portion 5 is provided between the evaporation section 3 and the condensation section 4, and is made into a closed tube.

[0039] Among them, the evaporation part 3, Figure 1 (a) is formed at one end side of the sealed container 2 and has the function of receiving heat (absorbing heat) from the heat-generating element 9 that is thermally connected. Specifically, the evaporation portion 3, such as Figure 2 As shown, for example, by using a liquid working fluid F L The working fluid F that evaporates and changes phase into a gas phase g , absorbing the heat received from the heating element 9 as latent heat of evaporation.

[0040] In the evaporation section 3, the heat generated from the heating element 9 is transferred to the first sintered body layer 6 via the sealed container 2, and further, the heat is transferred from the first sintered body layer 6 to the second sintered body layer 7. Figure 2 As shown, the liquid phase working fluid F supplied from the condensation section 4 to the evaporation section 3 L , in the evaporation portion 3, it is supplied from the second sintered body layer 7 to the first sintered body layer 6. Therefore, the liquid phase working fluid F in the evaporation portion 3 L Working fluid F to gas phase g The phase change mainly occurs in the first sintered body layer 6, but may also occur partially in the second sintered body layer 7. At this time, the working fluid F in the liquid phase in the first sintered body layer 6 L The gas phase working fluid F is generated by evaporation g , and moves to the internal space S through the gaps formed inside the second sintered body layer 7 .

[0041] Furthermore, the condensation unit 4 is disposed at a position separated from the evaporation unit 3, for example, Figure 1 The condenser 4 has the following functions: g The latent heat of evaporation is dissipated by heat exchange means (not shown). g The working fluid F that condenses and changes phase into a liquid phase L As a result, the heat transferred as the condensation latent heat of the working fluid F is released to the outside of the heat pipe 1 .

[0042] [Regarding the Structure of the First Sintered Body Layer]

[0043] The first sintered body layer 6 is a sintered body layer, which is composed of a sintered body of the first copper powder, and is formed in a specific area on the inner peripheral surface 2a of the closed container 2 when viewed from a cross section perpendicular to the longitudinal direction X of the heat pipe 1 in the evaporation portion 3. Since the first sintered body layer 6 is composed of a sintered body of the first copper powder with a smaller average particle size than the second sintered body layer 7 described later, the liquid working fluid F L The gap through which the fluid can flow is small, and the working fluid F in the liquid phase LThe circulation speed is slow. In addition, since the first sintered body layer 6 is adjacent to the inner peripheral surface 3a of the evaporation portion 3 of the sealed container 2, it is also a portion where the temperature is relatively easy to become high. Therefore, the flow of the working fluid F inside the first sintered body layer 6 is as follows: Figure 2 As shown in FIG. 1 , the working fluid F in the liquid phase supplied from the inner peripheral surface 6 a and infiltrating into the first sintered body layer 6 is mainly L The working fluid F in the liquid phase that has penetrated into the first sintered body layer 6 is L The gaseous working fluid F is generated by evaporation and flows from the inside of the first sintered body layer 6 through the inner peripheral surface 6a toward the internal space S. g By utilizing the mechanism generated by the first sintered body layer 6, the heat (heat absorption) received from the heating element (not shown) thermally connected to the sealed container 2 is transferred to the first sintered body layer 6, and most of the heat is retained in a specific area of ​​the inner peripheral surface 2a of the sealed container 2, so that the liquid working fluid F L Here, the specific area of ​​the inner peripheral surface 2a of the closed container 2 can be set as the following area in the closed container 2, which includes the area of ​​the inner peripheral surface 2a constituting the portion facing the heating element 9.

[0044] The first sintered body layer 6, such as Figure 1 As shown in (a), at least the evaporation portion 3 is provided. By providing such a first sintered body layer 6 in the evaporation portion 3, the liquid phase working fluid F in the evaporation portion 3 L The evaporation of the evaporator 3 is promoted, and the heat received from the heating element 9 in thermal contact with the evaporation portion 3 can be absorbed by more working fluid F as latent heat of evaporation.

[0045] Here, the arrangement length L1 of the first sintered body layer 6 is preferably longer than the length L0 of the evaporation portion 3 in the longitudinal section including the longitudinal direction X of the heat pipe 1. Thus, the first sintered body layer 6 is arranged adjacent to both the inner peripheral surface 3a of the evaporation portion 3 and the inner peripheral surface 5a of the intermediate portion 5. By configuring the arrangement length L1 of the first sintered body layer 6 in this way, the heat from the heating element 9 toward the intermediate portion 5 side can be conducted to the first sintered body layer 6 and absorbed by the working fluid F. In particular, from the viewpoint of efficiently allowing the heat from the heating element 9 toward the intermediate portion 5 side to be absorbed by the working fluid F, the first sintered body layer 6 is preferably arranged at least in the region of the inner peripheral surface 2a of the sealed container 2 that constitutes the portion facing the heating element 9, and the region of the inner peripheral surface 2a of the sealed container 2 adjacent to both sides of the region, in the longitudinal section. On the other hand, the upper limit of the arrangement 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 a production method described later.

[0046] In addition, when the first sintered body layer 6 is observed from a cross section perpendicular to the longitudinal direction X of the heat pipe 1, the length of the portion of the inner circumferential surface 2a of the sealed container 2 where the first sintered body layer 6 is disposed is preferably longer than the region of the inner circumferential surface 2a constituting the portion facing the heating element 9. In particular, when the first sintered body layer 6 is observed from a cross section, it is more preferably disposed at least in the region of the inner circumferential surface 2a constituting the portion facing the heating element 9 of the inner circumferential surface 2a of the sealed container 2 and the regions on the inner circumferential surface 2a of the sealed container 2 adjacent to both sides of the region. By constituting the first sintered body layer 6 in this way, the heat transferred from the heating element 9 to the sealed container 2 can be efficiently conducted to the first sintered body layer 6 and absorbed by the working fluid F.

[0047] In addition, the inner peripheral surface in this specification is a surface along the wall surface on the side of the internal space S. In addition, the outer peripheral surface in this specification is a surface along the wall surface on the side separated from the internal space S. In addition, the longitudinal dimension L0 of the evaporation portion 3 can be set to the dimension of the heat generating element 9 thermally connected to the heat pipe 1 along the longitudinal direction X of the heat pipe 1.

[0048] The first sintered body layer 6 is preferably formed of a porous material different from the bulk material and formed by sintering the first copper powder. By forming the first sintered body layer 6 with a porous material, the surface area of ​​the first sintered body layer 6 becomes larger, so that the liquid working fluid F can be efficiently L Furthermore, by forming the first sintered body layer 6 with a sintered body of copper powder, wettability with the working fluid F is improved and thermal conductivity can be improved.

[0049] Here, the average particle size (average primary particle size) of the first copper powder is not particularly limited, and may be, for example, in the range of 0.01 μm or more and 200 μm or less. The average particle size in this specification is the particle size when the integral value based on the volume basis in the particle size distribution measured by the laser diffraction scattering particle size distribution measurement method is 50%. In addition, the thickness of the first sintered body layer 6 is not particularly limited, and may be, for example, in the range of 0.1 mm or more and 1 mm or less.

[0050] [Regarding the Structure of the Second Sintered Body Layer]

[0051] The second sintered body layer 7 is a sintered body layer, which is composed of a sintered body of a second copper powder, the second copper powder having an average particle size larger than the average particle size of the first copper powder, and is observed from a cross section perpendicular to the long side direction X of the heat pipe 1 in the evaporation portion 3, and is formed in a ring shape by spreading over the entire inner peripheral surface 2a of the sealed container 2 when the first sintered body layer 6 is interposed between the second sintered body layer 7 and the inner peripheral surface 2a of the sealed container 2. Here, the second sintered body layer 7 is stacked on the inner peripheral surface 6a of the first sintered body layer 6, and is also stacked on the inner peripheral surface 2a of the sealed container 2 where the first sintered body layer 6 is not stacked, and these stacked parts of the second sintered body layer 7 are continuous and extended. Since the second sintered body layer 7 is composed of a sintered body of a second copper powder having an average particle size larger than the average particle size of the first sintered body layer 6, a large void is formed inside, and this void forms a liquid phase of the working fluid F L The flow path can flow, so the liquid working fluid F L In addition, the second sintered body layer 7 has a portion where the temperature is less likely to rise than in the first sintered body layer 6. Therefore, when viewed from a cross section perpendicular to the longitudinal direction X of the heat pipe 1, the flow of the working fluid F in the second sintered body layer 7 is as follows: Figure 2 As shown, the liquid phase working fluid F supplied from the condensation unit 4 mainly becomes: L The working fluid F flowing toward the first sintered body layer 6 along the inner peripheral surface 2a of the sealed container and mainly generated in the first sintered body layer 6 is a gas phase. g Flow towards the inner space S.

[0052] The arrangement length L2 of the second sintered body layer 7 is as follows: Figure 1 As shown in (a), when observing the longitudinal section of the heat pipe 1 including the longitudinal direction X, it is preferably longer than the arrangement length L1 of the first sintered body layer 6. In this case, the second sintered body layer 7 continuously extends from the inner peripheral surface 6a of the first sintered body layer 6 located in the evaporation portion 3 to the inner peripheral surface 5a of the middle portion 5. As a result, the liquid working fluid F absorbed by the second sintered body layer 7 on the inner peripheral surface 5a of the middle portion 5 is L Since the working fluid F in the liquid phase is smoothly supplied to the inner peripheral surface 6a of the first sintered body layer 6 through the gap formed inside the second sintered body layer 7, the working fluid F in the liquid phase before and after the boundary between the intermediate portion 5 and the evaporation portion 3 can be L In addition, the liquid working fluid F L Since the working fluid F in the liquid phase passes through the gap formed inside the second sintered body layer 7 and flows from the inner peripheral surface 5a of the middle portion 5 toward the front end of the evaporation portion 3 along the longitudinal direction X of the closed container, the working fluid F passing through the inside of the second sintered body layer 7 can be reduced. LThe gas phase working fluid F passing through the inner space S g contact, and at the same time be able to liquid phase working fluid F L The sintered body is supplied to a wider range of the inner peripheral surface 6 a of the first sintered body layer 6 located in the evaporation portion 3 .

[0053] Here, when the heat pipe 1 is viewed from a longitudinal section including the longitudinal direction X, the flow of the working fluid F inside the second sintered body layer 7 mainly consists of the liquid phase working fluid F being sucked into the inner peripheral surface 5a of the intermediate portion 5. L , along the long side direction X of the sealed container and toward the front end of the evaporation portion 3; and, mainly the gas phase working fluid F generated in the first sintered body layer 6 g Flow towards the inner space S.

[0054] In particular, the second sintered body layer 7 preferably ends at any position of the middle portion 5. At this time, the second sintered body layer 7 extends in a manner connecting the inner peripheral surface 6a of the first sintered body layer 6 and the inner peripheral surface 5a of the middle portion 5. In addition, the second sintered body layer 7 has: 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 middle portion 5 of the closed container 2. On the other hand, the second sintered body layer 7 preferably does not contact the condensation portion 4 from the viewpoint of lowering the temperature of the condensation portion 4 and promoting the condensation of the working fluid F.

[0055] Here, the working fluid F changes phase into a liquid phase in the condensation unit 4. L , preferably, the second sintered body layer 7 located in the middle portion 5 flows toward the evaporation portion 3 by the capillary force generated by the internal voids of the second sintered body layer 7, 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 liquid working fluid F L , is transported from the inner peripheral surface 5a of the middle portion 5 along the second sintered body layer 7 extending in the longitudinal direction X of the closed 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 working fluid F in the liquid phase is L Evaporation is performed more efficiently, and the thermal resistance of the heat pipe 1 can be reduced.

[0056] The second sintered body layer 7 is configured such that the liquid working fluid F L The liquid flow can flow at least in the internal gap of the second sintered body layer 7. At this time, the second sintered body layer 7 is preferably configured such that the working fluid F that changes phase into a gas phase in the evaporation portion 3 is g The vapor flow and the working fluid F which changes phase into liquid phase in the condensation section 4L Thus, the liquid phase working fluid F passing through the interior of the second sintered body layer 7 can be effectively isolated. L The gas phase working fluid F passing through the inner space S g The working fluid F in the gas phase in the evaporation portion 3 and the intermediate portion 5 is contacted with g Unexpected condensation becomes difficult to occur.

[0057] The second sintered body layer 7 is a porous material and is formed by a sintered body of a second copper powder having a larger average particle size than the first copper powder. L The pores can pass through, so the liquid working fluid F L , and is transported from the inner peripheral surface 5a of the middle 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 with a sintered body of copper powder, the wettability with the working fluid F is good and the thermal conductivity can be improved. Therefore, the second sintered body layer 7 has high thermal conductivity and can play a role in making the liquid phase working fluid F L The first sintered body layer 6 is subjected to evaporation resistance.

[0058] 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, and may be, for example, in the range of 100 μm or more and 500 μm or less. In addition, 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, and may be, for example, in the range of 2 or more and 5 or less. On the other hand, the thickness of the second sintered body layer 7 is not particularly limited, and may be, for example, in the range of 0.3 mm or more and 5 mm or less.

[0059] The area ratio of the second sintered body layer 7 to the total area of ​​the first sintered body layer 6 and the second sintered body layer 7 is preferably within a range of 50% to 90% when the evaporation portion 3 is observed from 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 working fluid F passing through the interior of the second sintered body layer 7 is L Increase, so the reflux efficiency of the working fluid F can be further improved.

[0060] [About the working principle of heat pipe]

[0061] Next, use Figure 1 and Figure 2 The heat pipe 1 of the first embodiment shown in FIG. 1 is used to explain the operating principle of the heat pipe 1. Here, the heat pipe 1 is a liquid working fluid F before operation. L The state of being enclosed in the internal space S.

[0062] First, the liquid working fluid F L , is supplied to the portion of the inner peripheral surface 2a in the sealed container 2 that is connected to the second sintered body layer 7. The liquid working fluid F L The supply means to the portion of the sealed container 2 connected to the second sintered body layer 7 is not particularly limited. For example, the second sintered body layer 7 and the liquid working fluid F L The capillary force generated during contact can move the liquid working fluid F L Since the oxygen is supplied to the entire second sintered body layer 7 , it is possible to prevent evaporation from occurring.

[0063] The liquid phase working fluid F supplied to the portion of the inner peripheral surface 2a of the closed container 2 that is in contact with the second sintered body layer 7 L , is configured such that at least a portion of the liquid is absorbed by the second sintered body layer 7 and can flow through 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 sealed container 2 as described later, the liquid working fluid F L The liquid flow can also 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.

[0064] The liquid working fluid F absorbed by the second sintered body layer 7 L , flows along the longitudinal direction X by the capillary force of the second sintered body layer 7, and is absorbed by the first sintered body layer 6 in a wide range where the second sintered body layer 7 and the first sintered body layer 6 are in contact. On the other hand, the working fluid F that is not absorbed by the second sintered body layer 7 and flows in the groove 8 L , in the portion where the groove 8 is adjacent to the first sintered body layer 6 or the second sintered body layer 7 , it is absorbed by the first sintered body layer 6 or the second sintered body layer 7 .

[0065] Here, when the evaporation portion 3 of the heat pipe 1 receives heat from the heat generating element 9 which is thermally connected, the evaporation portion 3 of the heat pipe 1 is supplied with the liquid phase working fluid F. L The surface of the first sintered body layer 6 is made to have a liquid working fluid F L The working fluid F that evaporates and changes phase into a gas phase g In particular, in the heat pipe 1, the liquid working fluid F is efficiently used in the portion of the closed container 2 facing the heating element 9 and its vicinity. L The working fluid F changes into a gas phase g , so the thermal resistance of the heat pipe 1 can be made very small.

[0066] The gas phase working fluid F after absorbing heat in the evaporation section 3 g, passes through the internal space S of the sealed container 2, that is, the vapor flow path, and flows from the evaporation part (heat receiving part) 3 to the condensation part (heat dissipation part) 4 along the long side direction X of the sealed container 2, whereby the heat received from the heating element 9 is transferred from the evaporation part 3 to the condensation part 4 through the intermediate part 5. At this time, the gas phase working fluid F transferred from the evaporation part 3 to the condensation part 4 through the intermediate part 5 is g Due to the liquid working fluid F flowing inside the second sintered body layer 7 L It is difficult to contact, so it can prevent the working fluid F from being g The circulation flow of the working fluid F is disturbed due to the backflow of the working fluid F. Therefore, in the heat pipe 1, excellent heat transfer characteristics can be achieved.

[0067] Then, the gas phase working fluid F is sent to the condensation unit 4. g In the condensation section 4, the phase of the liquid phase is changed to a liquid phase by heat exchange means (not shown). At this time, the heat of the heat generating element 9 transmitted is released to the outside of the heat pipe 1 as condensation latent heat. In addition, the liquid phase working fluid F which releases heat and changes phase to a liquid phase in the condensation section 4 is L , along the longitudinal direction X, the inner circumferential surface 2a of the sealed container 2 is supplied to the portion of the inner circumferential surface 2a connected to the second sintered body layer 7 in the sealed container 2, thereby forming a circulation flow of the working fluid between the evaporation section 3 and the condensation section 4.

[0068] <Second Embodiment>

[0069] Figure 3 is a diagram showing the internal structure of a heat pipe according to a second embodiment. Figure 3 (a) is a longitudinal section view, Figure 3 (b) is along Figure 3 (a)II A -II A Cross-sectional view when the wire is cut, Figure 3 (c) is along Figure 3 (a)II B -II B Cross-sectional view when the wire is cut. Figure 3 The components shown in the figure are Figure 1 When the components of the heat pipe 1 shown are the same, the same reference numerals are used.

[0070] In the heat pipe 1 shown in the first embodiment, the inner peripheral surface 2a of the sealed container 2 is shown as a smooth surface, but the present invention is not limited to this. Figure 3 The heat pipe 1A shown in the figure may also be formed with a plurality of grooves 8 extending along the longitudinal direction X of the sealed container 2 on the inner peripheral surface 2a of the sealed container 2. By providing such grooves 8, when the liquid working fluid F is transported inside the heat pipe 1,L When the working fluid F L The capillary force is exerted so that the liquid working fluid F moves along the groove 8 and the second sintered body layer 7 on the inner peripheral surface 2a of the closed container 2A. Therefore, the liquid working fluid F can be accelerated from the condensation part 4 to the evaporation part 3. L Here, the so-called reverse working property refers to the performance of being able to function as the heat pipe 1 even if the evaporation part 3 is located higher than the condensation part 4.

[0071] The grooves 8 preferably extend in the longitudinal direction X at least on the inner peripheral surface 2a from the condensation section 4 to the portion where the second sintered body layer 7 is located. More preferably, the grooves 8 extend continuously from the condensation section 4 to the evaporation section 3. In this way, the liquid working fluid F from the condensation section 4 to the portion where the second sintered body layer 7 is located is L The transport of the liquid working fluid F to the first sintered body layer 6 located in the evaporation portion 3 via the second sintered body layer 7 is promoted. L In particular, by using the groove 8 that is continuous from the condensation section 4 to the evaporation section 3, the liquid phase working fluid F L The liquid is supplied to the first sintered body layer 6 located in the evaporation portion 3 through both the path inside the second sintered body layer 7 and the path in the flow groove 8 .

[0072] The sealed container 2A having the groove 8 may also be a grooved pipe in which the groove (groove) 8 extending in the longitudinal direction X of the sealed container 2A is formed on the inner circumferential surface 2a of the sealed container 2A. In particular, the sealed container 2A is formed by a grooved pipe, which extends over the entire length of the sealed container 2A. L The capillary force of the heat pipe 1A is equivalent to the working fluid F in the liquid phase. L Even if the evaporation section 3 downstream of the condensation section 4 is arranged above the condensation section 4 and the intermediate section 5, the liquid phase working fluid F can be easily transferred from the condensation section 4 to the evaporation section 3. L of transportation.

[0073] The opening width of the grooves 8 is not particularly limited, and the capillary force is used to promote the liquid working fluid F L From the perspective of transportation, for example, it can also be set to 0.1mm~1mm.

[0074] The first sintered body layer 6A of the heat pipe 1A preferably also fills the groove 8 formed in a specific area on the inner peripheral surface 2a of the sealed container. That is, the first sintered body layer 6A is preferably formed in a manner that includes one side of the sealed container 2A compared to the hypothetical inner peripheral surface 3b in the case where the groove 8 is not formed in the evaporation portion 3 of the sealed container. The first sintered body layer 6A is more preferably filled in a part or all of the long side direction X of the groove 8. In particular, the first sintered body layer 6A, such as Figure 3 As shown in (b), it is preferably formed in a manner that is connected to the bottom of the groove 8. In this way, the liquid working fluid F transported along the groove 8 L By contacting with the first sintered body layer 6A, the liquid phase working fluid F can be further promoted because it is easily absorbed by the first sintered body layer 6A. L of evaporation.

[0075] Here, the inner peripheral surface of the first sintered body layer 6A is as follows: Figure 3 As shown in FIG. 2A , it is preferably configured such that the boundary surface position N where the second sintered body layer 7A located in the middle portion 5 connects with the inner peripheral surface 2a of the closed container 2A is located closer to the central axis position M of the internal space S of the closed container 2A. L A part of the liquid flow will collide with the first sintered body layer 6A, so that the liquid phase working fluid F from the second sintered body layer 7A to the first sintered body layer 6A can be promoted. L circulation.

[0076] In addition, the first sintered body layer 6A can also form a space where the groove 8 can exist between the inner peripheral surface 2a of the closed container 2A and the outer peripheral surface 6b of the first sintered body layer 6A. L , more quickly moves through the groove 8 to the position of the evaporation portion 3 present on the outer peripheral surface of the first sintered body layer 6A, and as a result, the liquid phase working fluid F from the condensation portion 4 to the evaporation portion 3 can be further promoted. L Circulation flow.

[0077] The second sintered body layer 7A of the heat pipe 1A is preferably configured to convert the working fluid F into a gas phase in the evaporation portion 3. g The vapor flow and the working fluid F which changes phase into liquid phase in the condensation section 4 L The liquid flow is actually isolated, and the liquid phase working fluid F L The liquid flow is divided into a path passing through the plurality of grooves 8 and a path passing through the internal gaps of the second sintered body layer 7A. As a result, more liquid phase working fluid F can be made available in the portion where the second sintered body layer 7A and the grooves 8 are arranged. LFlow, so that the liquid phase working fluid F in this part L In addition, in the portion where the paths through the plurality of grooves 8 and the paths through the internal voids of the second sintered body layer 7A are formed in parallel, the liquid phase working fluid F L is sucked more strongly, so the liquid working fluid F in the intermediate portion 5 and the evaporation portion 3 L The circulation speed becomes faster, thereby further improving the heat transfer characteristics of the heat pipe 1A.

[0078] 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 can be, for example, in the range of 100 μm or more and 500 μm or less, as in the heat pipe 1 described above. On the other hand, the average particle size (average primary particle size) of the second copper powder constituting the second sintered body layer 7A does not interfere with the liquid phase of the working fluid F formed in the groove 8. L From the perspective of the flow path, it is preferably larger than the groove width of groove 8.

[0079] The second sintered body layer 7A does not hinder the liquid phase working fluid F formed in the groove 8. L From the perspective of the flow path, it is preferred that the groove 8 is not filled. Here, as means for forming the second sintered body layer 7A in a manner without filling the groove 8, there can be cited: a means of using a copper powder having a larger average particle size than the first copper powder as the second copper powder, and a means of sintering the copper powder by weakening the force applied to the copper powder when the second copper powder is filled in the sealed container 2, etc.

[0080] <Other Implementation Methods>

[0081] In the above embodiment, the sealed container 2 extends toward one side of the evaporation section 3 and has the condensation section 4 and the intermediate section 5 at each location, but the present invention is not limited to this structure. For example, the sealed container 2 may extend from the evaporation section 3 in multiple directions and the condensation section 4 and the intermediate section 5 may be provided at multiple locations. In the heat pipe 1, even if the sealed container 2 extends from the evaporation section 3 in multiple directions and the liquid working fluid F L The flow rate is increased, and the heat received from the heat generating element 9 as latent heat of evaporation can be efficiently transferred to the plurality of condensation portions.

[0082] <Method for manufacturing heat pipe>

[0083] A specific example of a method for manufacturing a heat pipe will be described below.

[0084] The shape of the sealed container 2 such as a tubular container used in the heat pipe 1 can be appropriately selected from a tube material, a plate material, a foil material, etc. according to the shape of the heat pipe 1. Dirt and the like attached to the surface of the sealed container 2 may reduce the heat transfer performance of the heat pipe, so it is preferably cleaned. Cleaning can be performed by a common method, for example, by solvent degreasing, electrolytic degreasing, etching, oxidation treatment, etc.

[0085] A core rod (e.g., a stainless steel core rod) in the shape of a mold of the first sintered body layer 6 is inserted and arranged at the center of the interior of the sealed container 2, and then the raw material of the first sintered body layer 6, that is, the first copper powder, is filled in the gap formed between the inner peripheral surface 2a of the sealed container 2 and the outer surface of the core rod, and the filled first copper powder is sintered to form the first sintered body layer 6. The core rod is pulled out and removed from the sealed container 2 after the first sintered body layer 6 is formed. Here, from the perspective of providing the first sintered body layer only in a specific area on the inner peripheral surface 2a of the sealed container 2, the formed first sintered body layer 6 may also be subjected to cutting processing or the like.

[0086] Next, a core rod (e.g., a stainless steel core rod) in the shape of a mold of the second sintered body layer 7 is inserted and arranged at the center of the sealed container 2, and then the second copper powder, which is the raw material of the second sintered body layer 7, is filled in the gap formed between the inner surface of the sealed container 2 and the outer surface of the core rod, and the filled second copper powder is sintered to form the second sintered body layer 7. The core rod is pulled out and removed from the sealed container 2 after the second sintered body layer 7 is formed.

[0087] Here, the sintering of the raw materials of the first sintered body layer 6 and the second sintered body layer 7, that is, the first copper powder and the second copper powder, is not particularly limited as long as it is a commonly practiced condition. As an example of sintering conditions, it can be cited that: heating treatment is performed in an atmosphere of a reducing gas such as hydrogen or a mixed gas containing hydrogen and an inert gas (N2, Ar, He, etc.).

[0088] After the first sintered body layer 6 and the second sintered body layer 7 are formed in the sealed container 2, one end, i.e., the sealing port, is left and only the other end of the sealed container 2 is sealed, and then the working fluid F is injected from the sealing port. After the working fluid F is injected, the inside of the sealed container 2 is subjected to a degassing treatment such as heating degassing or vacuum degassing to be in a reduced pressure state. Thereafter, the sealing port is sealed, thereby manufacturing the heat pipe 1.

[0089] The sealing method is not particularly limited. For example, argon (TIG) welding, resistance welding, crimping, and soldering are used. In addition, the initial sealing (sealing of only the other end) is a step for sealing the portion other than the portion used to remove the internal gas when degassing is performed later; and the second sealing (sealing of the sealing port) is a step for sealing the portion used to remove the internal gas when degassing.

[0090] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects included in the concept of the present invention and the scope of the claims, and various changes can be made within the scope of the present invention.

[0091] [Example]

[0092] Hereinafter, the present invention will be described in further detail based on Examples, but the present invention is not limited to these Examples.

[0093] (Example of the present invention)

[0094] The heat pipe 1B of the present invention has Figure 1An example of a cylindrical heat pipe 1 having an internal structure shown. As the closed container 2, a cylindrical tubular container having a length of 400 mm along the longitudinal direction X and a diameter (inner diameter) of 7 mm is used. A stainless steel core rod in the shape of a mold of the first sintered body layer 6B is inserted and arranged at the inner center position of the closed container 2, and then the raw material of the first sintered body layer 6B, that is, copper powder (first copper powder) with an average particle size (average primary particle size) of 100 μm is filled in the gap formed between the inner surface of the groove tube and the outer surface of the core rod. In addition, the closed container 2 filled with the first copper powder is subjected to a heat treatment in an atmosphere of a reducing gas, and after the copper powder is sintered, the core rod is pulled out of the closed container 2 and removed. Thus, in a specific area on the inner peripheral surface 2a of the sealed container 2, more specifically, in an area with an area ratio of 67% relative to the entire area of ​​the inner peripheral surface 2a of the portion that becomes the evaporation section 3, the portion that becomes the evaporation section 3 includes the entire area of ​​the inner peripheral surface 2a constituting the portion facing the heating element 9, a first sintered body layer 6B composed of a copper sintered body with a thickness of 0.5 mm is formed. Here, when the portion that becomes the evaporation section 3 of the heat pipe 1B is observed from a cross section perpendicular to the long side direction X, the length of the area of ​​the inner peripheral surface 2a of the sealed container 2 constituting the portion facing the heating element 9 is set to 50% of the entire length of the inner peripheral surface 2a; the area where the first sintered body layer 6B is formed is arranged in a manner such that the sizes of the areas on both sides are equal in the area of ​​the inner peripheral surface 2a constituting the portion facing the heating element 9 and the areas on the inner peripheral surface 2a adjacent to the area. In addition, the area constituting the portion facing the heating element 9 in the inner peripheral surface 2a of the sealed container 2 is set in the range from the position of 15 mm to the position of 55 mm from the front end of the evaporation portion 3 side of the sealed container 2 when observed from the longitudinal section of the heat pipe 1B including the long side direction X, and the range from the front end of the evaporator 3 side to the position of 55 mm is set as the evaporation portion 3. Therefore, the long side dimension L0 of the evaporation portion 3 is 55 mm. In addition, when observed from the longitudinal section of the heat pipe 1B including the long side direction X, the first sintered body layer 6B is set in the range from the front end of the evaporation portion 3 side to the position of 60 mm. Therefore, the arrangement length L1 of the first sintered body layer 6B along the long side direction X is 60 mm.

[0095] Next, a stainless steel core rod in the shape of a mold for the second sintered body layer 7 is inserted and arranged at the inner center of the sealed container 2, and then the raw material of the second sintered body layer 7, that is, copper powder (second copper powder) with an average particle size (average primary particle size) of 200 μm is filled in the gap formed between the inner surface of the groove tube and the outer surface of the core rod. Furthermore, the sealed container 2 filled with the second copper powder is subjected to a heat treatment in a reducing gas atmosphere, and after the copper powder is sintered, the core rod is pulled out of the sealed container 2 and removed. In this way, Figure 4As shown in (a), from the front end of the evaporation portion 3 side of the sealed container 2 to the middle portion 5, in a state where the first sintered body layer 6B is partially interposed between the second sintered body layer 7 and the inner circumferential surface 2a of the sealed container 2, the entire inner circumferential surface 2a of the sealed container 2 when observed from a cross section perpendicular to the long side direction X forms a second sintered body layer 7 composed of a copper sintered body, the length of the second sintered body layer 7 along the long side direction X is 250 mm and the inner diameter of the inner circumferential surface is 5 mm (the thickness of the portion where the first sintered body layer 6B is formed is 0.5 mm, and the thickness of the portion where the first sintered body layer 6B is not formed is 1.0 mm).

[0096] After the first sintered body layer 6 and the second sintered body layer 7 are formed, the other end of the sealed container 2 is sealed while leaving one end, i.e., the sealed port, and then the liquid working fluid F is injected from the sealed port. L Next, the interior of the sealed container 2 is deaerated to a reduced pressure state, and then the sealed opening is sealed, thereby manufacturing the heat pipe 1.

[0097] (Comparative Example)

[0098] The heat pipe 10 of the comparative example, Figure 4 As shown in (b), a first sintered body layer 6C composed of a copper sintered body is formed on the entire inner peripheral surface 2a of the sealed container 2, and the first sintered body layer 6C has a length of 60 mm and a thickness of 0.5 mm along the longitudinal direction X. Other than this, the heat pipe is manufactured in the same structure as the heat pipe of the present invention.

[0099] Here, Figure 4 is a cross-sectional view showing the internal structure of the heat pipe of the present invention example and the comparative example, Figure 4 (a) is a cross-sectional view of a heat pipe 1 according to an example of the present invention. Figure 4 (b) is a cross-sectional view of a heat pipe 10 according to a comparative example.

[0100] (Performance Evaluation)

[0101] The performance evaluation of the heat pipe was carried out under the following conditions.

[0102] 1. Install a heating block (heating capacity 50W~250W) as a heating element on the outer surface of one end of the heat pipe, that is, the evaporation part (heat receiving part).

[0103] 2. Install the heat exchange means at the other end of the heat pipe, that is, the condensation part (heat dissipation part).

[0104] 3. The middle part between the evaporation part and the condensation part is provided with heat insulating material to form a heat insulating part.

[0105] 4. When the device is set in a horizontal direction, gradually increase the heat supply in the evaporation section from 50W, measure the heat supply when the difference between the temperature of the heating element and the temperature of the condensation section becomes the minimum, and set the measured heat supply as the maximum heat transfer amount Qmax (W).

[0106] 5. The difference between the temperature of the heating element and the temperature of the condensation portion was measured, and the value obtained by dividing by the heat supply was defined as thermal resistance (°C / W).

[0107] The results of the maximum heat transfer amount Qmax are shown as relative values ​​when the comparative example in which the first sintered body layer 6 is formed on the entire surface of the inner peripheral surface 2a of the closed container 2 is used as a reference (index ratio 100). The results are shown in the "Relative value of maximum heat transfer amount" column of Table 1.

[0108] [Table 1]

[0109]

[0110] As a result, the relative value of the maximum heat transfer amount Qmax of the heat pipe 1 of the present invention example is 128 when the comparative example in which the first sintered body layer 6 is formed on the entire inner peripheral surface 2a of the closed container 2 is used as a reference (index ratio 100).

[0111] Therefore, the heat pipe 1 of the present invention example has a relatively larger maximum heat transfer amount Qmax than the heat pipe 10 of the comparative example, and thus it is found that the heat pipe 1 of the present invention example has a high heat transfer characteristic.

[0112] Reference numerals

[0113] 1,1A:Heat pipe

[0114] 2,2A: Closed container

[0115] 2a: Inner surface of sealed container

[0116] 3: Evaporation section

[0117] 3a: Inner surface of the evaporation section of the sealed container

[0118] 3b: Hypothetical inner surface of the evaporation portion of the sealed container

[0119] 4: Condensation section

[0120] 5: Middle part

[0121] 5a: Inner circumference of the middle part of the sealed container

[0122] 6,6A: 1st sintered body layer

[0123] 6a: Inner surface of the first sintered body layer

[0124] 6b: Outer surface of the first sintered body layer

[0125] 7,7A: Second sintered body layer

[0126] 7b: The outer peripheral surface of the second sintered body layer located on the inner peripheral surface of the first sintered body layer

[0127] 7b': The outer peripheral surface of the second sintered body layer located on the inner peripheral surface of the middle portion of the sealed container

[0128] 8: Groove

[0129] 9: Heating element

[0130] 10: Heat pipe of comparative example

[0131] F: Working fluid

[0132] F L :Liquid working fluid

[0133] F g : Gas phase working fluid

[0134] L0: Long side dimension of the evaporation part

[0135] L1: Arrangement length of the first sintered body layer

[0136] L2: Arrangement length of the second sintered body layer

[0137] M: The central axis position of the internal space of the closed container

[0138] N: The position of the boundary surface where the second sintered body layer located in the middle part connects with the inner peripheral surface of the sealed container

[0139] S: Internal space

[0140] X: Long side direction of the sealed container

[0141] Y: thickness direction of the sealed container

[0142] Z: Depth direction of the closed container

Claims

1. A heat pipe, comprising: an evaporation section for evaporating a liquid-phase working fluid and changing its phase into a gas-phase working fluid; a condensation section for condensing the gas-phase working fluid and changing its phase into a liquid-phase working fluid; and an intermediate section for being located between the evaporation section and the condensation section; in, The heat pipe, when viewed from the cross section of the heat pipe in the evaporation section, comprises: a first sintered body layer, which is composed of a sintered body of a first copper powder and is formed in a specific area on the inner peripheral surface of the sealed container; and The second sintered body layer is composed of a sintered body of a second copper powder, the average particle size of the second copper powder is larger than the average particle size of the first copper powder, and is spread over the entire inner surface of the aforementioned closed container to form a ring shape when the aforementioned first sintered body layer is interposed between the second sintered body layer and the inner surface of the aforementioned closed container.

2. The heat pipe according to claim 1, wherein: When observing the longitudinal section of the heat pipe including the longitudinal direction, the arrangement length of the first sintered body layer is longer than the longitudinal dimension of the evaporation portion, 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 claim 2, wherein: The second sintered body layer ends at any position of the intermediate portion.

4. The heat pipe according to claim 3, wherein: The working fluid that changes phase into a liquid phase in the aforementioned condensation section is constructed as follows: it flows toward the aforementioned evaporation section by means of capillary force generated by the internal gaps of the aforementioned second sintered body layer located in the middle section, and flows from the aforementioned second sintered body layer toward the aforementioned first sintered body layer through the contact interface between the outer peripheral surface of the aforementioned second sintered body layer and the inner peripheral surface of the aforementioned first sintered body layer.

5. The heat pipe according to claim 1, wherein: The specific area includes an area of ​​the inner peripheral surface of the portion of the sealed container that faces the heating element.

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

7. The heat pipe according to claim 6, wherein: The first sintered body layer is also formed to fill the groove located in the specific area.

8. The heat pipe according to claim 6, wherein: The aforementioned second sintered body layer is constructed to actually isolate the vapor flow of the working fluid that changes phase into the gas phase in the aforementioned evaporation section from the liquid flow of the working fluid that changes phase into the liquid phase in the aforementioned condensation section, and the aforementioned liquid flow is divided into a path passing through the aforementioned multiple grooves and a path passing through the internal voids of the aforementioned second sintered body layer.

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