1. A loop type heat pipe is composed of a pair of outermost metal layers and a middle metal layer arranged between the pair of outermost metal layers, and comprises:

an evaporator for vaporizing a working fluid;

a condenser for liquefying the working fluid;

a liquid pipe connecting the evaporator and the condenser; and

a vapor pipe connecting the evaporator and the condenser and forming a loop-shaped flow path together with the liquid pipe,

the intermediate metal layer includes:

a pair of wall portions that constitute a part of tube walls of the evaporator, the condenser, the liquid tube, and the vapor tube;

a porous body provided between the pair of wall portions; and

a first support penetrating the porous body and joining the pair of outermost metal layers to each other,

the intermediate metal layer is composed of one or more than two metal layers,

the metal layers each have:

a first portion that constitutes at least a part of the wall portion;

a second part which is connected to the first part and constitutes at least a part of the porous body; and

and a third portion connected to the second portion and constituting at least a part of the first pillar.

2. The loop heat pipe of claim 1,

the first support is formed integrally with the porous body.

3. The loop heat pipe of claim 1 or 2,

the first support is solid.

4. The loop heat pipe according to any one of claims 1 to 3,

the intermediate metal layer is composed of more than two metal layers,

the third portion is a solid portion,

the third portions are joined to each other between two or more of the metal layers to form the first support.

5. The loop heat pipe according to any one of claims 1 to 4,

each of the third portions includes a region overlapping with the other third portions in a plan view.

6. The loop heat pipe according to any one of claims 1 to 5,

the third portion is aligned between the two or more metal layers in plan view.

7. The loop heat pipe according to any one of claims 1 to 6,

the intermediate metal layer has the first pillars at a plurality of positions between the pair of wall portions.

8. The loop heat pipe according to any one of claims 1 to 7,

the porous bodies are arranged in pairs in the liquid pipe,

a part of the first support penetrates one of the pair of porous bodies,

the other part of the first support penetrates the other of the pair of porous bodies,

one of the pair of porous bodies is formed integrally with one of the pair of wall portions,

the other of the pair of porous bodies is formed integrally with the other of the pair of wall portions,

a space through which the working fluid flows is provided between the pair of porous bodies.

9. The loop heat pipe according to any one of claims 1 to 7,

the porous body is provided in the liquid pipe so as to be separated from the pair of wall portions,

spaces through which the working fluid flows are provided between the porous body and one of the pair of wall portions, and between the porous body and the other of the pair of wall portions.

10. The loop heat pipe according to claim 8 or 9,

the first leg extends along the fluid tube.

11. The loop heat pipe according to any one of claims 1 to 10,

the porous body is provided in the evaporator,

the porous body is formed in a comb-tooth shape having a coupling portion and a plurality of protruding portions having one end coupled to the coupling portion when viewed in a plan view,

the intermediate metal layer further includes:

a second support penetrating the connection portion; and

and a third support penetrating the protrusion.

12. A method for manufacturing a loop heat pipe comprising a pair of outermost metal layers and an intermediate metal layer provided between the pair of outermost metal layers, the loop heat pipe comprising: an evaporator for vaporizing a working fluid; a condenser for liquefying the working fluid; a liquid pipe connecting the evaporator and the condenser; and a vapor pipe connecting the evaporator and the condenser and forming a loop-shaped flow path together with the liquid pipe,

the method for manufacturing a loop heat pipe includes a step of forming the intermediate metal layer from one or two or more metal layers, the intermediate metal layer including a pair of wall portions that constitute parts of tube walls of the evaporator, the condenser, the liquid tube, and the vapor tube, a porous body provided between the pair of wall portions, and a first support column that penetrates the porous body and joins the pair of outermost metal layers to each other,

the step of forming the intermediate metal layer includes a step of forming a first portion, a second portion, and a third portion in each of the metal layers by etching the one or more metal layers, the first portion constituting at least a part of the wall portion, the second portion being connected to the first portion and constituting at least a part of the porous body, and the third portion being connected to the second portion and constituting at least a part of the first pillar.

Background

Heat pipes are known as devices for cooling heat generating components such as a cpu (central Processing unit) mounted on an electronic apparatus. A heat pipe is a device that transfers heat by using the phase change of a working fluid.

As an example of the heat pipe, a loop type heat pipe may be mentioned, which includes: an evaporator for vaporizing a working fluid by heat of a heat generating component; and a condenser for cooling and liquefying the vaporized working fluid, wherein the evaporator and the condenser are connected by a liquid pipe and a vapor pipe for forming a loop-shaped flow path. In the loop type heat pipe, the working fluid flows in one direction in the loop-shaped flow path.

In addition, a porous body is provided in the evaporator and the liquid pipe of the loop heat pipe, and the working fluid in the liquid pipe is induced to the evaporator by the capillary force generated by the porous body, and the backflow of the vapor from the evaporator to the liquid pipe is suppressed. Many pores are formed in the porous body. Each pore is formed such that a bottomed hole formed in one surface side of the metal layer and a bottomed hole formed in the other surface side communicate with each other (see, for example, patent documents 1 and 2).

< Prior Art document >

< patent document >

Patent document 1: japanese patent application laid-open No. 6291000

Patent document 2: japanese patent application laid-open No. 6400240

Patent document 3: japanese laid-open patent publication No. 11-183067

Disclosure of Invention

< problems to be solved by the present invention >

In the conventional loop heat pipe, there is a concern that deformation may occur due to a change in volume of the working fluid caused by a change in temperature.

An object of the present invention is to provide a loop heat pipe and a method of manufacturing the loop heat pipe capable of suppressing deformation due to a volume change of a working fluid.

< means for solving the problems >

According to one aspect of the present invention, there is provided a loop heat pipe including a pair of outermost metal layers and an intermediate metal layer provided between the pair of outermost metal layers, the loop heat pipe including: an evaporator for vaporizing a working fluid; a condenser for liquefying the working fluid; a liquid pipe connecting the evaporator and the condenser; and a vapor pipe which connects the evaporator and the condenser and forms a loop-shaped flow path together with the liquid pipe, wherein the intermediate metal layer includes: a pair of wall portions that constitute a part of tube walls of the evaporator, the condenser, the liquid tube, and the vapor tube; a porous body provided between the pair of wall portions; and a pillar that penetrates the porous body and bonds the pair of outermost metal layers to each other, wherein the intermediate metal layer is composed of one or more metal layers, and each of the metal layers has: a first portion that constitutes at least a part of the wall portion; a second part which is connected to the first part and constitutes at least a part of the porous body; and a third portion that is connected to the second portion and that constitutes at least a part of the pillar.

< effects of the invention >

According to the present invention, deformation due to a change in the volume of the working fluid can be suppressed.

Drawings

Fig. 1 is a schematic plan view illustrating a loop heat pipe according to a first embodiment.

Fig. 2 is a sectional view of the evaporator and its surroundings of the loop heat pipe of the first embodiment.

Fig. 3 is a plan view showing a liquid pipe of the loop heat pipe of the first embodiment by way of example.

Fig. 4 is (a) a sectional view showing a liquid pipe of the loop heat pipe of the first embodiment by way of example.

Fig. 5 is an exploded view of fig. 4.

Fig. 6 is a sectional view (second) illustrating a liquid pipe of the loop heat pipe according to the first embodiment.

Fig. 7 is an exploded view of fig. 6.

Fig. 8 is a plan view showing an evaporator of the loop heat pipe of the first embodiment by way of example.

Fig. 9 is (a) a sectional view showing an example of an evaporator of the loop heat pipe according to the first embodiment.

Fig. 10 is a sectional view (second) showing an example of the evaporator of the loop heat pipe of the first embodiment.

Fig. 11 (a) is a view illustrating a process of manufacturing a loop heat pipe according to the first embodiment.

Fig. 12 is a diagram (second diagram) illustrating a manufacturing process of the loop heat pipe according to the first embodiment.

Fig. 13 is a plan view showing a liquid pipe of the loop heat pipe according to modification 1 of the first embodiment by way of example.

Fig. 14 is a cross-sectional view of a loop heat pipe according to modification 2 of the first embodiment.

Fig. 15 is a diagram illustrating an example of an evaporator of a loop heat pipe according to modification 3 of the first embodiment.

Fig. 16 is a plan view showing a liquid pipe of the loop heat pipe of the second embodiment by way of example.

Fig. 17 is a sectional view (first) showing a liquid pipe of a loop heat pipe according to a second embodiment by way of example.

Fig. 18 is a sectional view (second) illustrating a liquid pipe of the loop heat pipe according to the second embodiment.

Fig. 19 is a plan view illustrating a liquid pipe of a loop heat pipe according to a modification of the second embodiment.

Description of the reference numerals:

1 loop type heat pipe

10 evaporator

20 condenser

30 vapor tube

40 liquid pipe

50 flow path

60 porous body

61-66 metal layer

81-83 support post

90 pipe wall

91 wall part

621. 631, 641, 651 first part

622. 632, 642, 652 second part

623. 633, 643, 653 third part

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description thereof may be omitted.

(first embodiment)

[ Structure of Loop Heat pipe in first embodiment ]

First, the structure of the loop heat pipe according to the first embodiment will be described. Fig. 1 is a schematic plan view illustrating a loop heat pipe according to a first embodiment.

Referring to fig. 1, a loop type heat pipe 1 has an evaporator 10, a condenser 20, a vapor pipe 30, and a liquid pipe 40. The loop type heat pipe 1 can be accommodated in a portable electronic device 2 such as a smartphone, a tablet terminal, or the like.

In the loop heat pipe 1, the evaporator 10 has a function of vaporizing the working fluid C and generating the vapor Cv. The condenser 20 has a function of liquefying the vapor Cv of the working fluid C. The evaporator 10 and the condenser 20 are connected to each other by a vapor pipe 30 and a liquid pipe 40, and a flow path 50 serving as a loop through which the working fluid C or the vapor Cv flows is formed by the vapor pipe 30 and the liquid pipe 40.

Fig. 2 is a sectional view of the evaporator and its surroundings of the loop heat pipe of the first embodiment. As shown in fig. 1 and 2, for example, four through holes 10x are formed in the evaporator 10. The bolts 150 are inserted into each through hole 10x formed in the evaporator 10 and each through hole 100x formed in the circuit board 100, and the bolts 150 are fixed by nuts 160 from the lower surface side of the circuit board 100, so that the evaporator 10 and the circuit board 100 are fixed to each other. The evaporator 10, the condenser 20, the vapor tube 30, and the liquid tube 40 have an upper surface 1a and a lower surface 1b on the opposite side of the upper surface 1 a. The upper surface 1a is an example of a 1 st main surface, and the lower surface 1b is an example of a 2 nd main surface. In the present invention, the top view is a view from a direction perpendicular to the upper surface 1 a.

A heat generating component 120 such as a CPU or the like is mounted on the circuit board 100, for example, by bumps 110, and the upper surface of the heat generating component 120 is in close contact with the lower surface of the evaporator 10. The working fluid C in the evaporator 10 is vaporized by heat generated by the heat generating component 12, thereby generating vapor Cv.

As shown in fig. 1, the vapor Cv generated in the evaporator 10 is introduced into the condenser 20 through the vapor pipe 30, and is liquefied in the condenser 20. This allows heat generated by the heat generating component 120 to be transferred to the condenser 20, thereby suppressing a temperature rise of the heat generating component 120. The working fluid C liquefied in the condenser 20 is introduced into the evaporator 10 through the liquid pipe 40. The width W of the steam pipe 30 can be set₁For example about 8 mm. Also, the width W of the liquid pipe 40 can be set₂For example about 6 mm.

The kind of the working fluid C is not particularly limited, however, it is preferable to use a fluid having a high evaporation pressure and a high latent heat of evaporation, so as to effectively cool the heat generating component 120 by the latent heat of evaporation. Examples of such fluids include ammonia, water, freon, ethanol, and acetone.

The evaporator 10, the condenser 20, the vapor tube 30, and the liquid tube 40 may have a structure in which a plurality of metal layers are stacked, for example. As will be described later, the evaporator 10, the condenser 20, the vapor tube 30, and the liquid tube 40 have a structure in which six layers of metal layers 61 to 66 are stacked (see fig. 4 to 7). In the evaporator 10, the condenser 20, the vapor tube 30, and the liquid tube 40, the metal layers 61 and 66 are outermost metal layers, and the metal layers 62 to 65 are intermediate metal layers. However, the evaporator 10, the condenser 20, the vapor tube 30, and the liquid tube 40 may include a pair of outermost metal layers as outermost layers, and an intermediate metal layer in which one or more metal layers are stacked between the outermost metal layers.

The metal layers 61 to 66 are, for example, copper layers having excellent thermal conductivity, and are directly bonded to each other by solid-phase bonding or the like. The thickness of each of the metal layers 61 to 66 may be set to, for example, about 50 μm to 200 μm. The metal layers 61 to 66 are not limited to copper layers, and may be formed of stainless steel layers, aluminum layers, magnesium alloy layers, or the like. The number of metal layers to be stacked is not limited, and 5 or less, 7 or more metal layers may be stacked.

The evaporator 10, the condenser 20, the vapor pipe 30, and the liquid pipe 40 each have a pipe wall 90 formed by stacking all the metal layers 61 to 66 at both ends in a direction perpendicular to both the flow direction of the working fluid C or the vapor Cv thereof and the stacking direction of the metal layers 61 to 66.

Here, the structure of the liquid tube 40 will be explained. Fig. 3 to 7 are diagrams illustrating a liquid pipe of the loop heat pipe according to the first embodiment. Fig. 3 is a plan view of a portion a in fig. 1. Fig. 4 is a sectional view taken along line IV-IV in fig. 3, and fig. 5 is an exploded view of fig. 4. Fig. 6 is a sectional view taken along line VI-VI in fig. 3, and fig. 7 is an exploded view of fig. 6. In fig. 3, the metal layer (the metal layer 61 shown in fig. 4 to 7) as the outermost layer on one side is omitted in order to show the planar shape of the porous body and the support in the liquid pipe 40. In fig. 3 to 7, the stacking direction of the metal layers 61 to 66 is set to the Z direction, any direction in a plane perpendicular to the Z direction is set to the X direction, and a direction orthogonal to the X direction in the plane is set to the Y direction (the same as in the other figures). In the present invention, the plan view is a plan view from the Z direction.

As shown in fig. 3 to 7, the intermediate metal layer (metal layers 62 to 65) of the liquid pipe 40 includes a pair of wall portions 91 constituting a part of the pipe wall 90 and the porous body 60 between the pair of wall portions 91. In the intermediate metal layer (metal layers 62 to 65) of the liquid pipe 40, a solid support 81 is provided which penetrates the porous body 60 and joins the metal layer 61 and the metal layer 66.

The porous body 60 is in contact with the lower surface of the first metal layer 61 (the outermost metal layer on one side) and the upper surface of the sixth metal layer 66 (the outermost metal layer on the other side). No holes or grooves are formed in the metal layers 61 and 66. On the other hand, as shown in fig. 4 to 7, a plurality of bottomed holes 62x recessed from the upper surface side toward the substantially central portion in the thickness direction and a plurality of bottomed holes 62y recessed from the lower surface side toward the substantially central portion in the thickness direction are formed in the metal layer 62 constituting the second layer of the porous body 60.

The bottomed holes 62X and the bottomed holes 62y are alternately arranged in the X direction in a plan view. In addition, the bottomed holes 62x and the bottomed holes 62Y are alternately arranged in the Y direction in plan view. The bottomed holes 62X and the bottomed holes 62y alternately arranged in the X direction partially overlap in a plan view, and the overlapping portions communicate with each other, thereby forming the fine holes 62 z. The bottomed holes 62x and the bottomed holes 62Y alternately arranged in the Y direction are formed with a predetermined interval therebetween, and do not overlap in plan view. Therefore, the bottomed holes 62x and the bottomed holes 62Y alternately arranged in the Y direction do not form pores.

The bottomed holes 62x and 62y may be circular with a diameter of about 100 to 300 μm, for example, but may be formed in any shape such as an ellipse or a polygon. The depth of the bottomed holes 62x and the bottomed holes 62y may be set to, for example, about half the thickness of the metal layer 62. The interval between adjacent bottomed holes 62x may be set to, for example, about 100 μm to 400 μm. The interval between adjacent bottomed holes 62y may be set to, for example, about 100 μm to 400 μm.

The inner walls of the bottomed holes 62x and 62y may be set in a tapered shape that widens from the bottom surface side toward the opening side. However, the inner walls of the bottomed holes 62x and 62y may be perpendicular to the bottom surface. The shapes of the inner wall surfaces of the bottomed holes 62x and 62y are not limited to the tapered shape or the perpendicular shape. For example, the inner wall surfaces of the bottomed hole 62x and the bottomed hole 62y may be formed in a concave shape formed by a curved surface. The concave shape formed by the curved surface may be a concave shape having a cross-sectional shape of a substantially semicircular shape or a substantially semi-elliptical shape. The width of the fine holes 62z in the width direction may be set to about 10 μm to 50 μm, for example. The width of the fine pores 62z in the longitudinal direction may be set to, for example, about 50 μm to 150 μm.

As shown in fig. 4 to 7, the metal layer 63 constituting the third layer of the porous body 60 is formed with a plurality of bottomed holes 63x recessed from the upper surface side toward a substantially central portion in the thickness direction and a plurality of bottomed holes 63y recessed from the lower surface side toward a substantially central portion in the thickness direction.

In the metal layer 63, only the rows in which the bottomed holes 63X are arranged in the X direction and only the rows in which the bottomed holes 63Y are arranged in the X direction are alternately arranged in the Y direction. In the rows alternately arranged in the Y direction, the bottomed holes 63x and the bottomed holes 63Y of adjacent rows partially overlap in plan view, and the overlapped portions communicate with each other to form the fine holes 63 z.

However, the centers of the bottomed holes 63X and 63y adjacent to each other forming the fine hole 63z are displaced in the X direction. In other words, the bottomed holes 63X and the bottomed holes 63Y forming the fine holes 63z are arranged alternately in the oblique directions with respect to the X direction and the Y direction. The shapes of the bottomed holes 63x, 63y and the fine hole 63z may be set to be the same as the shapes of the bottomed holes 62x, 62y and the fine hole 62z, for example.

The bottomed hole 62y of the metal layer 62 and the bottomed hole 63x of the metal layer 63 are formed at positions overlapping in a plan view. Therefore, pores are not formed at the interface between the metal layer 62 and the metal layer 63. The bottomed holes 62y and 63x may be arranged offset in plan view, and the fine holes may be formed at the interface between the metal layer 62 and the metal layer 63.

As shown in fig. 4 to 7, a plurality of bottomed holes 64x recessed from the upper surface side toward a substantially central portion in the thickness direction and a plurality of bottomed holes 64y recessed from the lower surface side toward a substantially central portion in the thickness direction are formed in the metal layer 64 constituting the fourth layer of the porous body 60.

The bottomed holes 64X and the bottomed holes 64y are alternately arranged in the X direction in plan view. The bottomed holes 64x and the bottomed holes 64Y are alternately arranged in the Y direction in plan view. The bottomed holes 64X and the bottomed holes 64y alternately arranged in the X direction partially overlap in plan view, and the overlapped portions communicate with each other to form the fine holes 64 z. The bottomed holes 64x and the bottomed holes 64Y alternately arranged in the Y direction are formed with a predetermined interval and do not overlap when viewed from above. Therefore, the bottomed holes 64x and the bottomed holes 64Y alternately arranged in the Y direction do not form pores. The shapes of the bottomed holes 64x, 64y and the fine hole 64z may be set to be the same as the shapes of the bottomed holes 62x, 62y and the fine hole 62z, for example.

The bottomed hole 63y of the metal layer 63 and the bottomed hole 64x of the metal layer 64 are formed at positions overlapping in a plan view. Therefore, pores are not formed at the interface between the metal layer 63 and the metal layer 64. The bottomed holes 63y and 64x may be arranged offset in plan view, and the fine holes may be formed at the interface between the metal layer 63 and the metal layer 64.

As shown in fig. 4 to 7, in the metal layer 65 constituting the fifth layer of the porous body 60, a plurality of bottomed holes 65x recessed from the upper surface side toward the substantially central portion in the thickness direction and a plurality of bottomed holes 65y recessed from the lower surface side toward the substantially central portion in the thickness direction are formed, respectively.

In the metal layer 65, only the rows in which the bottomed holes 65X are arranged in the X direction and only the rows in which the bottomed holes 65Y are arranged in the X direction are alternately arranged in the Y direction. In the rows alternately arranged in the Y direction, the bottomed holes 65x and the bottomed holes 65Y of adjacent rows partially overlap in plan view, and the overlapped portions communicate with each other to form the fine holes 65 z.

However, the center positions of the bottomed holes 65X and 65y adjacent to each other forming the fine hole 65z are shifted in the X direction. In other words, the bottomed holes 65X and the bottomed holes 65Y forming the fine holes 65z are arranged alternately in the oblique direction with respect to the X direction and the Y direction. The shapes of the bottomed holes 65x, 65y and the fine hole 65z may be set to be the same as the shapes of the bottomed holes 62x, 62y and the fine hole 62z, for example.

The bottomed hole 64y of the metal layer 64 and the bottomed hole 65x of the metal layer 65 are formed at positions overlapping in plan view. Therefore, pores are not formed at the interface between the metal layer 64 and the metal layer 65. The bottomed hole 64y and the bottomed hole 65x may be arranged offset in plan view, and a fine hole may be formed at the interface between the metal layer 64 and the metal layer 65.

The pores formed in each metal layer communicate with each other, and the communicated pores are three-dimensionally distributed in the porous body 60. Therefore, the working fluid C is three-dimensionally distributed in the interconnected pores by the capillary force.

At least a part of the bottomed holes constituting the porous body 60 communicates with the flow path 50 in the condenser 20. Thereby, the working fluid C can permeate into the porous body 60.

Thus, the liquid pipe 40 is provided with the porous body 60, and the porous body 60 extends along the liquid pipe 40 to the vicinity of the evaporator 10. Thereby, the liquid-phase working fluid C in the liquid pipe 40 is guided to the evaporator 10 by the capillary force generated in the porous body 60.

As a result, even if the vapor Cv tries to flow back in the liquid pipe 40 due to heat leakage from the evaporator 10 or the like, the vapor Cv can be pushed back by the capillary force acting on the liquid-phase working fluid C by the porous body 60, and the backflow of the vapor Cv can be prevented.

An injection port (not shown) for injecting the working fluid C is formed in the liquid pipe 40, and the injection port is sealed by a sealing member, so that the inside of the loop heat pipe 1 is kept airtight.

The support columns 81 are disposed at a plurality of positions in the liquid pipe 40 so as to penetrate the porous body 60, for example. The support column 81 extends along the liquid pipe 40, for example, and has a rectangular planar shape extending in the direction (Y direction) in which the working fluid C flows in a planar view. For example, the pillars 81 are arranged in a lattice shape in a plan view. That is, the plurality of support columns 81 are arranged in the Y direction, and the plurality of support columns 81 are arranged in the X direction.

As shown in fig. 4 to 7, the metal layer 62 of the second layer includes a first portion 621 constituting a part of the wall 91, a second portion 622 constituting a part of the porous body 60, and a third portion 623 constituting a part of the support post 81. The second portion 622 is joined to the first portion 621, and the third portion 623 is joined to the second portion 622. No holes or grooves are formed in the first portion 621 and the third portion 623. In the second portion 622, a bottomed hole 62x, a bottomed hole 62y, and a fine hole 62z are formed. As described later, the first portion 621, the second portion 622, and the third portion 623 are formed by etching one metal layer. That is, the first portion 621, the second portion 622, and the third portion 623 are integrally formed.

As shown in fig. 4 to 7, the metal layer 63 of the third layer includes a first portion 631 constituting a part of the wall 91, a second portion 632 constituting a part of the porous body 60, and a third portion 633 constituting a part of the support 81. The second portion 632 is coupled to the first portion 631, and the third portion 633 is coupled to the second portion 632. The holes and grooves are not formed in the first part 631 and the third part 633. In the second portion 632, a bottomed hole 63x, a bottomed hole 63y, and a fine hole 63z are formed. As described later, the first, second, and third parts 631, 632, and 633 are formed by etching one metal layer. That is, the first, second, and third parts 631, 632, and 633 are integrally formed.

As shown in fig. 4 to 7, the metal layer 64 of the third layer includes a first portion 641 constituting a part of the wall portion 91, a second portion 642 constituting a part of the porous body 60, and a third portion 643 constituting a part of the pillar 81. The second portion 642 is connected to the first portion 641, and the third portion 643 is connected to the second portion 642. No holes or grooves are formed in the first part 641 and the third part 643. In the second portion 642, a bottomed hole 64x, a bottomed hole 64y, and a fine hole 64z are formed. As described later, the first portion 641, the second portion 642, and the third portion 643 are formed by etching one metal layer. That is, the first portion 641, the second portion 642, and the third portion 643 are integrally formed.

As shown in fig. 4 to 7, the metal layer 65 of the third layer includes a first portion 651 constituting a part of the wall 91, a second portion 652 constituting a part of the porous body 60, and a third portion 653 constituting a part of the support 81. The second portion 652 is coupled to the first portion 651, and the third portion 653 is coupled to the second portion 652. No holes or grooves are formed in the first portion 651 and the third portion 653. In the second portion 652, a bottomed hole 65x, a bottomed hole 65y, and a fine hole 65z are formed. As described later, the first portion 651, the second portion 652, and the third portion 653 are formed by etching one metal layer. That is, the first portion 651, the second portion 652, and the third portion 653 are integrally formed.

The first portions 621, 631, 641, and 651 are solid portions. The third portions 623, 633, 643, and 653 are also solid portions. When viewed from above, the first portions 621, 631, 641, and 651 overlap each other, the second portions 622, 632, 642, and 652 overlap each other, and the third portions 623, 633, 643, and 653 overlap each other. In addition, as described above, the metal layers 61 to 66 are directly bonded to each other by solid-phase bonding or the like. The first portions 621, 631, 641, and 651 are joined to each other to constitute the wall portion 91. The pipe wall 90 is formed by a part of the metal layer 61, the wall 91, and a part of the metal layer 66. The second portions 622, 632, 642, and 652 are joined to each other to constitute the porous body 60. The third portions 623, 633, 643 and 653 engage one another to form a solid strut 81. The pillars 81 are bonded to the metal layer 61 and the metal layer 66.

Next, the structure of the evaporator 10 will be explained. Fig. 8 to 10 are diagrams illustrating an evaporator of a loop heat pipe according to a first embodiment. Fig. 8 is a plan view. Fig. 9 is a sectional view taken along line IX-IX in fig. 8. Fig. 10 is a cross-sectional view taken along line X-X in fig. 8. In fig. 8, the metal layer (the metal layer 61 shown in fig. 9 to 10) as the outermost layer on one side is not shown in order to show the planar shape of the porous body and the pillars in the evaporator 10.

As shown in fig. 8 to 10, the intermediate metal layer (metal layers 62 to 65) of the evaporator 10 includes a pair of wall portions 91 constituting a part of the tube wall 90 and the porous body 60 between the pair of wall portions 91. Further, in the intermediate metal layer (metal layers 62 to 65) of the evaporator 10, solid pillars 82 and 83 which penetrate the porous body 60 and join the metal layer 61 and the metal layer 66 are provided.

As shown in fig. 8, the porous body 60 in the evaporator 10 includes a coupling portion 60v and a protrusion portion 60 w.

The connection portion 60v is provided on the side closest to the liquid tube 40 in the X direction (the side where the evaporator 10 is connected to the liquid tube 40) in a plan view, and extends in the Y direction. A part of the surface of the connection portion 60v on the side of the liquid pipe 40 is connected to the pipe wall 90 of the evaporator 10, and the remaining part is connected to the porous body 60 provided in the liquid pipe 40. A part of the surface of the connection portion 60v on the steam pipe 30 side is connected to the protrusion 60w, and the remaining part is connected to the space 70.

The plurality of protrusions 60w protrude from the connection portion 60v toward the steam pipe 30 when viewed in a plan view.

The protrusions 60w are arranged in parallel at predetermined intervals in the Y direction, and the end of each protrusion 60w on the steam pipe 30 side is separated from the pipe wall 90 of the evaporator 10. The end portions of the respective protrusions 60w on the steam pipe 30 side are not connected to each other. On the other hand, the end portions of the respective projections 60w on the side of the liquid pipe 40 are connected to each other by a connecting portion 60 v. In other words, the porous body 60 in the evaporator 10 is formed in a comb-tooth shape having the coupling portion 60v and the plurality of protrusions 60w in a plan view.

In the evaporator 10, a space 70 is formed in a region where the porous body 60 is not provided. The space 70 is connected to the flow path 50 of the vapor tube 30.

The working fluid C is guided from the liquid pipe 40 side to the evaporator 10, and further permeates into the porous body 60. In the evaporator 10, the working fluid C having permeated the porous body 60 is vaporized by the heat generated in the heat generating component 120 to generate vapor Cv, and the vapor Cv flows toward the vapor tube 30 through the space 70 in the evaporator 10. In fig. 8, the number of the projections 60w (comb teeth) is set to three as an example, and the number of the projections 60w (comb teeth) can be determined as appropriate. When the contact area between the protrusion 60w and the space 70 is increased, the working fluid C is easily evaporated, and the pressure loss can be reduced.

The struts 82 are disposed at a plurality of positions in the coupling portion 60v so as to penetrate the porous body 60, for example. The support column 82 has, for example, an elliptical shape in plan view with the X-axis direction as the short axis direction and the Y-axis direction as the long axis direction. For example, the plurality of support columns 82 are arranged in the Y direction.

For example, one support 83 is disposed in each protrusion 60w so as to penetrate the porous body 60. The support post 83 has, for example, a rectangular shape in plan view extending in the X direction.

The porous body 60 in the evaporator 10 has the same configuration as the porous body 60 in the liquid pipe 40. The support 82 and the support 83 have the same configuration as the support 81. That is, the first portions 621, 631, 641 and 651 of the metal layers 62 to 65 are bonded to each other to constitute the wall portion 91. The tube wall 90 of the evaporator 10 is formed by a part of the metal layer 61, the wall 91, and a part of the metal layer 66. The second portions 622, 632, 642 and 652 of the metal layers 62 to 65 are joined to each other to constitute the porous body 60 in the evaporator 10. The third portions 623, 633, 643 and 653 of the metal layers 62-65 are joined to one another to form the solid posts 82 and 83. The pillars 82 and 83 are joined to the metal layer 61 and the metal layer 66.

Thus, the support 81 is provided in the liquid pipe 40, and the metal layer 61 and the metal layer 66 are joined by the support 81. Further, the evaporator 10 is provided with a pillar 82 and a pillar 83, and the pillar 82 and the pillar 83 join the metal layer 61 and the metal layer 66. Thus, even if the volume of the working fluid C or the vapor Cv thereof changes due to a change in temperature such as an ambient temperature used for the loop heat pipe 1, deformation of the loop heat pipe 1 can be suppressed. Since the support columns 81 to 83 are solid members, that is, solid members in which holes, grooves, and the like are not formed, the support columns 81 to 83 can firmly join the metal layer 61 and the metal layer 66.

In the case where the support columns 81, 82, and 83 are not provided, the volume of the working fluid C changes due to the phase change of the working fluid C of the liquid penetrating into the porous body 60, and peeling may occur between the porous body 60 and the metal layer 61 and between the porous body 60 and the metal layer 66. When such peeling occurs, the working fluid C also penetrates into the interface where the peeling occurs, and the volume change may increase. Further, if a large volume change occurs, there is a possibility that a member or the like near the loop heat pipe 1 is pressed or that the metal layers 61 and 66 are broken near the pipe wall 90.

In contrast, in the present embodiment, since the support columns 81, 82, and 83 are provided so as to penetrate the porous body 60, even if a temperature change of this degree occurs, a change in the distance between the metal layer 61 and the metal layer 66 in the vicinity of the porous body 60 can be suppressed. That is, the loop heat pipe 1 can suppress deformation such as expansion, and can suppress peeling between the porous body 60 and the metal layer 61 and between the porous body 60 and the metal layer 66.

[ method for manufacturing Loop Heat pipe in first embodiment ]

Next, the method for manufacturing the loop heat pipe according to the first embodiment will be described mainly with reference to the manufacturing process of the porous body. Fig. 11 and 12 are diagrams illustrating a process of manufacturing the loop heat pipe according to the first embodiment. Fig. 11 and 12 are cross sections corresponding to fig. 4. Although not shown, in the steps shown in fig. 11 and 12, the same processing as that of the cross section corresponding to fig. 4 is performed also in the cross sections corresponding to fig. 6, 9, and 10.

First, in the step shown in fig. 11 (a), a metal sheet 620 formed in the shape of a plan view of fig. 1 is prepared. Then, a resist layer 310 is formed on the upper surface of the metal sheet 620, and a resist layer 320 is formed on the lower surface of the metal sheet 620. The metal sheet 620 is the final metal layer 62 component, which may be formed of, for example, copper, stainless steel, aluminum, magnesium alloy, or the like. The thickness of the metal sheet 620 may be set to about 50 μm to 200 μm, for example. As the resist layers 310, 320, for example, a photosensitive dry film resist or the like can be used.

Next, in the step shown in fig. 11 (b), in the region of the metal sheet 620 where the porous body 60 is to be formed, the resist layer 310 is exposed to light and developed to form the opening 310x so that the upper surface of the metal sheet 620 is selectively exposed. In addition, the resist layer 320 is exposed to light and developed to form the opening portions 320x so that the lower surface of the metal sheet 620 is selectively exposed. The shape and arrangement of the openings 310x, 320x are formed to correspond to the shape and arrangement of the bottomed holes 62x, 62y shown in fig. 4.

Next, in the step shown in fig. 11 (c), the metal piece 620 exposed in the opening 310x is half-etched from the upper surface side of the metal piece 620, and the metal piece 620 exposed in the opening 320x is half-etched from the lower surface side of the metal piece 620. Thus, the bottom hole 62x is formed on the upper surface side of the metal piece 620, and the bottom hole 62y is formed on the lower surface side. Further, since the openings 310X and the openings 320X alternately arranged on the front and back sides in the X direction partially overlap in a plan view, the overlapping portions communicate with each other to form the fine holes 62 z. In the half etching of the metal sheet 620, for example, a ferric chloride solution may be used.

Next, in the step shown in fig. 11 (d), the resists 310 and 320 are peeled off by a peeling liquid. Thereby, the metal layer 62 is completed. The metal layer 62 includes a first portion 621, a second portion 622, and a third portion 623. In this manner, the first portion 621, the second portion 622, and the third portion 623 are formed by etching one piece of the metal sheet 620. As shown in fig. 11 (d), the second portion 622 and the third portion 623 are coupled to each other. In addition, the first portion 621 and the second portion 622 are connected to each other by a portion not shown in the cross section shown in fig. 11 (d).

Next, in the step shown in fig. 12 (a), a solid metal layer 61 and a metal layer 66 are prepared without forming holes or grooves. In addition, the metal layers 63, 64, and 65 are formed by the same method as the metal layer 62. The positions of the bottomed holes and the fine holes formed in the metal layers 63, 64, and 65 are shown in fig. 4, for example.

Next, in the step shown in fig. 12 (b), the metal layers are stacked in the order shown in fig. 12 (a), and solid-phase bonding is performed by applying pressure and heat. At this time, the third portions 623 to 653 of the metal layers 62 to 65 are aligned so as to overlap each other in a plan view. Thereby, the adjacent metal layers are directly joined to each other, the loop type heat pipe 1 having the evaporator 10, the condenser 20, the vapor pipe 30, and the liquid pipe 40 is completed, and the porous body 60 is formed in the liquid pipe 40 and the evaporator 10. The support columns 81-83 are formed so as to penetrate the porous body 60. After that, the inside of the liquid tube 40 is evacuated by a vacuum pump or the like, the working fluid C is injected into the liquid tube 40 from an injection port, not shown, and then the injection port is closed.

Here, the solid-phase bonding refers to a method of: the objects to be joined are heated and softened while they are kept in a solid-phase (solid) state without melting, and are joined by being plastically deformed by being pressed. Preferably, the materials of all the metal layers 61 to 66 are set to be the same, so that adjacent metal layers can be bonded to each other well by solid-phase bonding.

In this manner, by setting the structure in which the bottomed hole portions formed from both sides of each metal layer are communicated with each other and the pores are provided in each metal layer, the pores having a constant size can be formed in the metal layer. This prevents the capillary force generated by the pores from being reduced due to the uneven size of the pores, and stably achieves the effect of suppressing the backflow of the vapor Cv from the evaporator 10 to the liquid pipe 40.

In addition, by setting the structure in which the entire adjacent bottomed holes are overlapped in the portion where the metal layers are laminated, the area where the metal layers are in contact with each other can be made large, and strong bonding becomes possible. For example, the third portions 623 to 653 of the metal layers 62 to 65 overlap each other in a plan view, and therefore the third portions 623 to 653 are strongly pressed between the metal layer 61 and the metal layer 66, and the pillars 81 to 83 are strongly bonded to the metal layer 61 and the metal layer 66.

The porous body 60 may be provided in a part of the condenser 20 or in a part of the steam pipe 30.

(modification 1 of the first embodiment)

In modification 1 of the first embodiment, the arrangement of the support columns 81 is different from that of the first embodiment. In modification 1 of the first embodiment, the description of the same components as those of the already described embodiment may be omitted. Fig. 13 is a plan view showing a liquid pipe of the loop heat pipe according to modification 1 of the first embodiment by way of example. Fig. 13 is a plan view of a portion corresponding to portion a in fig. 1. Fig. 13 is a plan view of the porous body and the support in the liquid pipe 40. Illustration of the metal layer 61 is omitted.

In modification 1 of the first embodiment, as shown in fig. 13, the positions of the columns 81 adjacent to each other in the X direction are shifted in the Y direction. The other configurations are the same as those of the first embodiment.

The same effects as those of the first embodiment can be obtained by modification 1.

It should be noted that the struts 81 need not be provided so as to be distributed in plural in the Y direction, and may be provided so that the struts 81 having the same length as the liquid pipe 40 extend from the condenser 20 to the evaporator 10.

(modification 2 of the first embodiment)

In modification 2 of the first embodiment, the structure of a part of the support columns 81 is different from that of the first embodiment. In modification 2 of the first embodiment, description of the same components as those of the already described embodiment may be omitted. Fig. 14 is a sectional view showing a liquid pipe of a loop heat pipe according to modification 2 of the first embodiment by way of example. Fig. 14 corresponds to the sectional view along the line IV-IV in fig. 3.

In modification 2 of the first embodiment, as shown in fig. 14, the positions of the third portions 623 to 653 included in a part of the support posts 81 are shifted in the X direction. However, in each strut 81, at least a part of the third section 623, a part of the third section 633, a part of the third section 643, and a part of the third section 653 overlap. That is, each of the third portions 623, 633, 643, and 653 includes an area overlapping with the other third portions in a plan view. The other configurations are the same as those of the first embodiment.

The same effects as those of the first embodiment can be obtained by modification 2. According to modification 2, it is easy to cope with various layouts of the porous body 60.

(modification 3 of the first embodiment)

In modification 3 of the first embodiment, the arrangement of the support posts 83 is different from that of the first embodiment. In modification 3 of the first embodiment, the description of the same components as those of the already described embodiment may be omitted. Fig. 15 is a diagram illustrating an example of an evaporator of a loop heat pipe according to modification 3 of the first embodiment. In fig. 15, the metal layer 61 is not shown in order to show the shapes of the porous body and the pillars in the evaporator 10 in a plan view.

In modification 3 of the first embodiment, as shown in fig. 15, three support columns 83 are arranged in the X direction in each projection 60 w. The other configurations are the same as those of the first embodiment.

According to modification 3, the same effects as those of the first embodiment can be obtained.

(second embodiment)

In the second embodiment, the liquid tube 40 is different in configuration from the first embodiment. In the second embodiment, description of the same components as those of the already described embodiment may be omitted. Fig. 16 to 18 are diagrams illustrating a liquid pipe of a loop heat pipe according to a second embodiment. Fig. 16 is a plan view of a portion corresponding to portion a in fig. 1. Fig. 17 is a sectional view taken along line XVII-XVII in fig. 16. Fig. 17 is a sectional view taken along line XVIII-XVIII in fig. 16. In fig. 16, the metal layer 61 is not shown in order to show the shapes of the porous body and the support in the liquid pipe 40 in a plan view.

In the second embodiment, as shown in fig. 16 to 18, the porous body 60 is provided at two locations in the liquid pipe 40 so as to be in contact with the pipe walls 90 on both sides. That is, the porous bodies 60 are provided in pairs in the liquid pipe 40. One porous body 60 is formed integrally with one wall portion 91, and the other porous body 60 is formed integrally with the other wall portion 91. The support 81 is disposed so as to penetrate each of the pair of porous bodies 60. A portion of the support 81 penetrates one of the porous bodies 60, and another portion of the support 81 penetrates the other of the porous bodies 60. A space 51 in which the working fluid C flows is formed between the two porous bodies 60. The space 51 is surrounded by the surfaces of the two porous bodies 60 facing each other, the lower surface of the metal layer 61, and the upper surface of the metal layer 66. The space 51 is a part of the flow path 50. At least a part of the bottomed holes constituting the porous body 60 communicates with the space 51. The other configurations are the same as those of the first embodiment.

According to the second embodiment, the same effects as those of the first embodiment can be obtained. In addition, the working fluid C can flow in the space 51.

(modification of the second embodiment)

In a modification of the second embodiment, the liquid pipe 40 is different from the second embodiment in configuration. In a modification of the second embodiment, the description of the same components as those of the already described embodiment may be omitted. Fig. 19 is a plan view illustrating a liquid pipe of a loop heat pipe according to a modification of the second embodiment. Fig. 19 is a plan view of a portion corresponding to portion a in fig. 1. In fig. 19, the metal layer 61 is not shown in order to show the shapes of the porous body and the support in the liquid pipe 40 in a plan view.

In the modification of the second embodiment, as shown in fig. 19, the porous body 60 is provided in the liquid pipe 40 so as to be separated from the pipe walls 90 on both sides. A space 51 through which the working fluid C flows is formed between the porous body 60 and one pipe wall 90 and between the porous body 60 and the other pipe wall 90. The space 51 is surrounded by the surfaces of the pipe wall 90 and the porous body 60 that face each other, the lower surface of the metal layer 61, and the upper surface of the metal layer 66. The space 51 is a part of the flow path 50. At least a part of the bottomed holes constituting the porous body 60 communicates with the space 51. The other configuration is the same as that of the second embodiment.

According to the modification of the second embodiment, the same effects as those of the second embodiment can be obtained.

Although the preferred embodiments and the like have been described above in detail, the embodiments and the like are not limited to the above embodiments and various modifications and substitutions may be made thereto without departing from the scope of the claims.