JP2001091172A - Planar heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wick of a planar heat pipe having a multi-hole structure wick from being collapsed. SOLUTION: The planar heat pipe 1 comprises planar parts 3, 5 facing in the thickness direction of a container 4 wherein at least one planar part 5 is provided with a plurality of posts 7 projecting toward the other planar part 3 and having a forward end face 11 touching the inner surface of the planar part 3. Porous layers 8, 10 are provided, respectively, on the entire inner surface of the planar parts 3, 5 except the joint of the post 7 and the forward end face 11. A liquid circulation member 9 of multi-hole structure coupling the porous layers 8, 10 is placed on the line connecting a pair of adjacent posts 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe for transporting heat as latent heat of a working fluid, and more particularly to a flat heat pipe in which a container has a hollow flat shape.

[0002]

2. Description of the Related Art A flat heat pipe forms a hermetically closed space inside a container having a hollow flat plate structure, and operates a condensable fluid in a state where a non-condensable gas such as air is degassed in the space. It is sealed as a fluid. In this type of heat pipe, the surface becomes flat, so that the contact area with the heat exchange object increases, and the heat transfer performance or heat exchange performance is improved. Is opposed to the condensing section through the space, so that it is necessary to take some measures to enable good operation in the top heat mode.

One example is described in Japanese Patent Application No. 8-106293. The flat heat pipe container has a flat heating section and a flat heat radiating section opposed to the heating section and having a small area. The entire inner wall surface of the container is sprayed with a predetermined thickness. A film is formed. Further, a spacer made of a sintered metal or a foamed metal is arranged between the inner surface of the heat radiating portion and the inner surface of the heating portion. Both ends of the spacer are in contact with the inner surface of the heating section and the inner surface of the heat radiating section, that is, the heating section and the heat radiating section are connected by the spacer.

Therefore, according to this flat heat pipe, the liquid-phase working fluid at the bottom of the container is pumped up by the capillary pressure generated in the spacer, and then penetrates the thermal spray coating and is diffused in the surface direction. In other words, since the spacer and the thermal spray coating function as a wick, it operates well even in the top heat mode.

[0005]

However, in the above-mentioned conventional structure, both the thermal spray coating and the spacer have a porous structure, and have not only a relatively low mechanical strength but also a flat shape. Since the heating part and the heat radiating part originally tend to bend when the container is not operated, particularly when the internal pressure of the container becomes a vacuum pressure, there is a possibility that the spacer and the thermal spray coating are crushed by the load from the outside of the container.

The present invention has been made in view of the above circumstances, and has as its object to provide a flat heat pipe capable of preventing collapse of a wick having a porous structure.

[0007]

Means for Solving the Problems and Actions As means for solving the above-mentioned problems, the invention according to the first aspect of the present invention is a method of condensing a hollow flat metal container inside a degassed state. In a flat heat pipe filled with a conductive fluid as a working fluid, at least one of the flat portions facing each other in the thickness direction of the container protrudes toward the other flat portion, and a tip end surface is an inner surface of the flat portion. Are provided, and a porous layer that generates a capillary pressure is provided on the entire inner surface of each of the flat plate portions except for a joint portion with the distal end surface, and a porous layer is provided. A liquid reflux member having a porous structure connecting layers is arranged on a line connecting a pair of adjacent columns.

Therefore, according to the first aspect of the present invention, for example, when a container is arranged in a state where a pair of flat plates face each other in the up-down direction and the upper flat plate is operated as a heating unit, the container is provided on the inner surface thereof. The working fluid in the liquid phase evaporates in the porous layer, and the working fluid vapor flows through the space between the columns and the liquid recirculation member to the other flat plate side having a low internal pressure, and radiates heat to the porous layer. To condense. Then, the heat is released from the outer surface of the flat plate portion to the outside.

On the other hand, the working fluid which has returned to the liquid phase moves from the inner surface of the lower flat plate portion to the base end side of each liquid reflux member due to the capillary pressure generated in the porous layer, and is transferred to the liquid reflux member. Due to the generated capillary pressure, the porous layer moves toward the distal end, and is further evaporated from the porous layer while being heated and evaporated. That is, the liquid reflux member and each porous layer act as a wick.

In this way, the working fluid is directly supplied to the upper evaporator through the plurality of liquid recirculation members. In addition, the working fluid is spread in a thin film on the surface of the evaporating section, so that a so-called good wettability is obtained. Therefore, the effective area of the evaporating section increases. As a result, heat transport is performed favorably even in the top heat mode.

In the flat heat pipe according to the first aspect of the present invention, since a pair of flexible flat plate parts is originally supported from the inside by a plurality of columns, the internal pressure of the heat pipe does not operate. Even at a vacuum pressure, the container is maintained in the desired hollow plate shape, and accordingly, damage to the porous layer is prevented. Further, according to the first aspect of the present invention, since each liquid reflux member is disposed between the pair of columns in the plan view, the load from the outside of the flat plate portion to each liquid reflux member is excessively large. Therefore, there is no possibility that the contact point of each liquid reflux member and each porous layer with each liquid reflux member is crushed.

The invention described in claim 2 is characterized in that the porous layer and the liquid reflux member are integrally formed of the same material.

Therefore, according to the second aspect of the present invention, the connection strength at the boundary between the porous layer and the liquid recirculation member, where the load from the outside of the flat plate portion is likely to concentrate, is improved, and accordingly the wick is formed. Overall strength against crushing is improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The flat heat pipe 1
The container 4 is constituted by a hollow flat-plate-shaped closed metal container including the main body 2 and the sealing plate 3. A working fluid (not shown) is sealed in the container 4 in a state where the non-condensable gas is degassed.

More specifically, the main body 2 has a bottom wall 5 made of a rectangular flat plate, and four sides (edges) of the bottom wall 5.
Are cup-shaped members formed by flat plate-shaped side wall portions 6 rising from the respective side walls. Each side wall 6 has a constant height and is set smaller than both the length and the width of the bottom wall 5. That is, the main body 2 has an opening width equal to or greater than its depth. Further, the bottom wall portion 5 is provided with four columns 7 protruding in the same direction as the side wall portions 6 (upward in FIG. 1). That is, the bottom wall 5
This corresponds to the flat plate portion of the present invention.

As an example, each of the columns 7 has a structure in which the bottom wall 5 is depressed in a cylindrical or conical shape with a vertically upward direction.
It is set at the same height as each side wall. In addition, each strut 7
Are on the opposing line connecting the opposing corners and the four sides of the bottom wall 5 (boundary portion with the side wall) as shown in FIG.
It is respectively arranged in the part on the central side than. Each of the columns 7 can be easily formed by pressing or forging a metal plate material that is a material of the main body 2.

On the other hand, a thermal spray coating 8 having a predetermined thickness is provided on the surface of the bottom wall 5 excluding the columns 7. The thermal spray coating 8 has a porous structure having pores between thermal spray particles bonded to each other, so that a large capillary pressure is generated. That is, the thermal spray coating 8 corresponds to the porous layer of the present invention.

On the upper part of the thermal spray coating 8, five cylindrical sintered blocks 9 are provided as an example. Each powder sintering block 9 corresponding to the liquid reflux member of the present invention
Is a porous structure in which, for example, a large number of copper particles or bronze particles are sintered and bonded, and a large capillary pressure is generated. The upper end surface of each powder sintering block 9 is formed on the inner surface of the sealing plate 3 by a thermal spray coating 1 described later.
0 is in contact.

The arrangement of the powder sintering blocks 9 will be described below. The center position of the bottom wall 5 in the plan view and the center axis of the pair of columns 7 located on the right side in FIG. Each of the powder sintering blocks 9 is provided at a position shifted to the right side and a position slightly shifted to the left side from a line connecting the central axes of the pair of columns 7 positioned at the left side in FIG. I have. Also, a position slightly shifted upward from a line connecting the central axes of the pair of columns 7 located on the upper side in FIG. 2 and a central axis of the pair of columns 7 located on the lower side in FIG. One powder sintering block 9 is provided at a position slightly shifted downward from the line. That is, each of the powder sintering blocks 9 is arranged to be sandwiched between a pair of adjacent columns 7.

On the other hand, the sealing plate 3 is a metal flat plate having the same size as the bottom wall portion 5 in a plan view, and the main body portion is closed in a state in which the opening formed by the upper edge of each side wall portion 6 is closed. 2 is assembled. That is, the inner surface of the sealing plate 3 and the tip end surface 11 of each column 7 are in close contact with each other. The joint between the sealing plate 3 and the main body 2 is sealed, for example, by welding to form a rectangular flat container 4.
Note that the sealing plate 3 corresponds to the flat plate portion of the present invention.

Further, a thermal spray coating 10 is formed on the inner surface of the sealing plate 3 except for abutting portions with the front end surfaces 11 of the columns 7 and abutting portions with the side walls. The thermal spray coating 10 has the same composition as that provided in the main body 2. That is, the thermal spray coating 10 corresponds to the porous layer of the present invention. Although not particularly shown, the container 4 is provided with an injection nozzle having a conventionally known structure.

Here, the thermal spray coatings 8 and 10 can be easily formed, for example, by performing plasma spraying or gas spraying before assembling the main body 2 and the sealing plate 3. That is, since the thermal spraying process is performed in the open space, there are advantages such as good operability of the thermal spraying torch, no heat accumulation, and easy cleaning. As the thermal spraying material, a different metal or ceramic or a cermet obtained by mixing them may be used as long as it has excellent thermal conductivity and heat resistance. Preferably, the thermal spraying material itself is excellent in thermal conductivity and heat resistance, and is used for a long time. Use a material that does not dissolve even when brought into contact with the working fluid.

Next, the operation of the above specific example will be described. For example, when the container 4 is held with the sealing plate 3 oriented horizontally and the lower side of the bottom wall 5 is heated in this state, the working fluid accumulated on the bottom of the main body 2 in the container 4 is heated and evaporated. I do. Therefore, the inner surface of the bottom wall 5 becomes the evaporator 16. The working fluid that has become steam flows upward in the gap between each of the columns 7 and the liquid recirculation member toward the lower side with a low pressure and temperature, and the thermal spray coating 1 provided on the inner surface of the sealing plate 3.
Dissipates heat to 0 and condenses. Therefore, the thermal spray coating 10 on the sealing plate 3 side becomes the condensing portion 17. The released heat is applied to the sealing plate 3
Is diffused from the outer surface to the surrounding space.

The condensed working fluid flows to the end of the powder sintering block 9 in the vicinity while being held on the inner surface of the sealing plate 3 by the capillary pressure generated in the gap between the spray particles, and the powder is sintered by the capillary pressure as it is. The other end of the tie block 9,
That is, it flows toward the bottom wall 5 side. Further, the working fluid penetrates from the end portion of each powder sintering block 9 to the surrounding thermal spray coating 8 and is diffused in the surface direction of the evaporating portion. Since the five powder sintering blocks 9 are dispersed and arranged in the plane direction of the bottom wall 5, a necessary and sufficient amount of working fluid is supplied to the entire area of the evaporator, and as a result, the heat transport capacity Becomes better.

Further, according to the above specific example, since the sealing plate 3 and the bottom wall portion 5 each having a flat plate shape are supported from the inside by the columns 7, the state in which the internal pressure of the container 4 is vacuum is obtained.
That is, even in the non-operation state, the desired shape of the container 4 can be maintained without bending in the direction in which the sealing plate 3 and the bottom wall portion 5 approach. Further, according to the above specific example, since the respective powder sintering blocks 9 are arranged at the intermediate portions between the columns 7 adjacent to each other, the outer side of the bottom wall 5 and the sealing plate 3 with respect to the liquid reflux member. Therefore, the portion of each of the powder sintered blocks 9 and each of the porous layers 8 and 10 in contact with each of the powder sintered blocks 9 can be prevented from being crushed.

Since each support 7 has a structure in which the bottom wall 5 is depressed by press working or forging, etc.
It can be easily formed, and accordingly, productivity as a flat heat pipe can be improved. Further, since each of the columns 7 constitutes a part of the container 4, there is an advantage that the weight is reduced as the flat heat pipe.

The number of the pillars and the sintered powder blocks and the arrangement of the bottom wall 5 in the plan view are not limited to the above specific examples, but are appropriately set based on the size of the target container. be able to. Further, the porous layer is not limited to a thermal spray coating, and may be, for example, a sintered metal particle.On the other hand, the liquid reflux member is not limited to a powder sintered block, and may be formed by, for example, a thermal spray coating. May be.
That is, the liquid reflux member and the porous layer may be integrally formed by, for example, a sintered metal or a thermal spray coating. With such a configuration, the connection strength at the boundary between them is improved, and as a result, the entire wick is formed. The strength against crushing is improved.

[0028]

As described above, in any of the inventions described in the claims, at least one of the flat portions opposed in the thickness direction of the container protrudes toward the other, and the front end surface of the flat portion is formed. A plurality of pillars in contact with the inner surface are provided, and a porous layer is provided on the entire inner surface of each flat plate portion except for a joint portion with the distal end surface, and a liquid reflux member having a porous structure connecting the porous layers to each other. Are arranged on a line connecting a pair of adjacent columns, and the liquid reflux member is disposed between the columns supporting the flat plate portion from the inside, so that an excessive load is applied to the liquid reflux member. It does not act, and therefore, it is possible to prevent crushing of the contact portion between the liquid reflux member and the porous layer with each liquid reflux member.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a specific example of the present invention.

FIG. 2 is a schematic diagram showing a partially cut-off state of a sealing plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flat heat pipe, 3 ... Sealing plate, 4 ... Container, 5 ... Bottom wall part, 7 ... Prop, 8, 10 ... Thermal spray coating,
9: powder sintered block, 11: tip surface.

Claims (2)

[Claims] 1. A flat heat pipe in which a condensable fluid is enclosed in a hollow flat metal container as a working fluid in a degassed state, wherein: At least one of the flat portions is provided with a plurality of columns protruding toward the other flat portion and having a distal end surface in contact with the inner surface of the flat plate portion. A porous layer that generates a capillary pressure is provided in the entire region except for the joint portion, and a liquid reflux member having a porous structure that connects the porous layers is disposed on a line that connects the pair of adjacent columns. A flat heat pipe. 2. The flat heat pipe according to claim 1, wherein the porous layer and the liquid reflux member are integrally formed of the same material.