JPH10103884A - Plate type heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the retaining of a heating unit and heat radiating unit as a surface substantially by a shape retaining member and prevent the deformation upon non-operating time or deformation due to external compression surely by a method wherein the shape retaining member of porous structure is filled into the container of a plate type heat pipe. SOLUTION: When an objective cooling member, such as an electronic instrument or the like, generates heat, the heat is transferred to a heating unit 11, positioned below the objective cooling member and contacted with the objective cooling member of a plate type heat pipe 9. Then, operating fluid, reserved in the bottom part of a container 10, is heated and evaporated. Accordingly, the inner surface of the heating unit 11 becomes an evaporating unit. In this case, a shape retaining member 15 is connected and fixed to the inner peripheral surface of the container 10 through a proper means such as fusion welding and the like. Therefore, a force, applied on the container 10 in accordance with the increase of an internal pressure, is transferred to the shape retaining member 15 and the force, applied on the container 10, is absorbed as the tensile stress of the shape retaining member 15 whereby the configuration of the container 10 can be retained surely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate type heat pipe suitable for cooling a small heating element having a flat portion.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a plate-type heat pipe used for cooling in electronic equipment such as a personal use computer (hereinafter referred to as a personal computer). The plate-type heat pipe 1 has a flat heating section 2, a flat heat radiating section 3 spaced apart from the heating section 2, and a peripheral edge of each of the heat radiating section 3 and the heating section 2. In a vacuum degassed state, a condensable fluid such as pure water or alcohol is provided as a working fluid 6 in a predetermined amount as a working fluid 6 inside a container 5 formed in a hollow flat shape by a flat side wall portion 4 connected to each other. It is enclosed.

According to such a conventional plate-type heat pipe 1, the electronic equipment having a flat surface, which is a heat source, is in direct contact with the flat surface, so that its substantial heat transport capability is extremely high. In addition, the cooling efficiency of the electronic device can be improved.

[0004] Incidentally, in the plate type heat pipe 1 as described above, if the planes serving as the heating section 2 and the heat radiating section 3 are widened conventionally, when the heat pipe 1 is not operated,
Since the inside of the container 5 is under a vacuum pressure, each flat portion may be deformed by the vacuum pressure, and is formed small. Further, since the container 5 of the heat pipe 1 may be deformed as the internal pressure increases during the operation of the heat pipe 1, it is usually used below the boiling point of the working fluid 6 sealed therein. is there.

[0005] However, in recent years, for example, the output of arithmetic processing units and the like has been increasing year by year with the increase in the functions of electronic devices used in personal computers and the like and the improvement in processing speed.
The amount of heat generated by the arithmetic processing unit and the like is also increasing, and the conventional plate-type heat pipe 1 has a disadvantage of insufficient cooling capacity. Therefore, it is necessary to increase the size of the heat pipe 1 or to use a heat pipe that can be used at a temperature higher than the boiling point of the working fluid 6. As described above, the heat pipe 1 has a hollow container 5 to secure a vapor flow path. In addition, since the working fluid 6 is sealed in a state in which the inside of the container 5 is vacuum degassed, in a state where there is no heat input from outside, that is, in a non-operating state, the internal pressure of the container naturally becomes the vacuum pressure. Has become. Therefore, if both the heating unit 2 and the heat radiating unit 3 facing each other are formed in a flat plate shape having a large area, since these members are made of copper or the like belonging to a soft class as a metal, the container 5 is not operated when it is not operated. There was a possibility that it would be deformed in the thickness direction (see FIG. 5). Further, when the container 5 is operated at a temperature equal to or higher than the boiling point of the working fluid 6, there is a possibility that the container 5 may be deformed due to an increase in internal pressure due to a phase change of the working fluid 6, and the container 5 is a hollow body. For this reason, there is a risk of deformation when receiving a compressive force from the outside.

That is, if the plane portion is enlarged or used at a temperature higher than the boiling point of the working fluid 6, the strength for maintaining the shape is insufficient, and the phase change of the working fluid 6 when the heat pipe is operated and when it is not operated. The deformation of the container 5 such as dents and swelling of the flat part may be caused by the change of the internal pressure accompanying this.

Therefore, conventionally, as shown in FIG. 6, the plane portions serving as the heating section 2 and the heat radiating section 3 are large,
As a plate-type heat pipe 7 which can be used at a temperature not lower than the boiling point, a column 8 for connecting the heating unit 2 and the heat radiating unit 3 to increase the strength in the thickness direction to maintain the shape is provided inside the container 5 at a predetermined interval. A heat pipe container provided with a predetermined space serving as a steam flow path has been developed.

The plate type heat pipe 7 thus formed is connected to, for example, a central processing unit (hereinafter referred to as C).
The heating unit 2 (lower surface) is attached to an upper surface of an electronic device such as a PU), that is, a member to be cooled.

Therefore, according to the plate type heat pipe 7, even if the member to be cooled generates heat above the boiling point of the working fluid 6, the heat pipe can be operated without deforming the shape of the container 5, and the heat is heated. When the working fluid 6 is transmitted to the section 2, the working fluid 6 sealed in the heat pipe 7 is heated and becomes steam, and the steam of the working fluid 6 moves to the low-temperature heat radiating section 3. Then, the heat carried in the state of the latent heat of vaporization of the working fluid 6 is radiated from the radiator 3. On the other hand, the working fluid 6 is deprived of heat in the heat radiating section 3, condenses, becomes a liquid phase again, and returns to the heating section 2. Then, by repeating the above cycle, the member to be cooled is cooled. In addition, since the heating unit 2 and the heat radiating unit 3 are supported by the pillars 8 that hold the shape, even when not in operation, the flat surface is prevented from being depressed by the vacuum pressure inside the container.

As described above, by using the plate-type heat pipe 7 having the support columns 8 for cooling the member to be cooled, a larger amount of heat can be transported in the state of latent heat of evaporation than in the prior art. The members can be cooled more effectively. Also, as a result,
For example, it is possible to prevent a personal computer from becoming inoperable or deteriorating due to overheating of a CPU or the like serving as a cooling target member.

[0011]

According to the plate-type heat pipe having the above-mentioned conventional supporting column, in addition to its extremely high heat transfer capability, it can be widely used for electronic equipment as a heat source. The direct contact with the area makes it possible to further improve the cooling efficiency of the electronic device.

However, in a conventional plate-type heat pipe, the member serving as the support pillar has a predetermined area and is continuously contacted in one direction with a surface serving as a heating portion or a heat radiating portion. Since the one that is arranged in a state or in contact with a plurality of predetermined locations is employed, there has been an inconvenience that the operation for forming the heat pipe is complicated.

That is, specifically, in the case of a supporting column which is arranged so as to be in contact with a surface serving as a heating section or a heat radiating section in one direction, the container can be integrally formed by appropriate means such as extrusion. However, since the formed pillars are formed in a continuous state in the extrusion direction, the inside of the container is separated by each pillar, and each has to be an independent heat pipe. That is, since the support pillars are formed in such a manner as to partition the inside of the container into a plurality of spaces, a plurality of heat pipes must be formed in an integral member. Therefore, each of the plurality of space portions has to be individually formed into a heat pipe, and there has been a problem that the operation is complicated.

Further, in the case of a rod-shaped support column in which both ends are in contact with a plurality of predetermined portions with respect to a surface serving as a heating portion or a heat radiation portion, when a container is extruded and formed. Since the supporting column cannot be integrally formed, for example, after forming a member to be a heat radiating portion and a member to be heated by appropriate means such as extrusion molding, respectively, the tip portion of the supporting column is appropriately formed by both members or It has to be bonded to one of the members and then combined with a member to be a heating unit and a member to be a heat radiating unit to form a container and further form a heat pipe, which has the disadvantage of complicating the work. .

In a conventional plate-type heat pipe, the support columns formed as described above are arranged with a predetermined distance therebetween in order to secure a steam flow path in the container. Are provided at predetermined intervals with respect to a surface serving as a heating unit and a heat radiating unit. Therefore, although the strength in the thickness direction has been improved, since the change in the flat surface corresponding to the change in the internal pressure will act intensively on the support pillar, the portion forming the steam flow path, The container may be deformed due to a pressure difference between the column and the portion where the column is provided. In addition, if the number of support columns is increased to minimize the amount of deformation, the operating speed as a heat pipe will decrease because the space part that becomes the steam flow path must be reduced. Some inconvenience may occur. Along with this, the ratio between the support pillars and the space must be taken into account in terms of both strength and cooling efficiency, and the number of pillars and the area of the space are changed depending on the size of the heat pipe. There were inconveniences that had to be adjusted and considered.

Further, when a local compressive force is received from the outside, since the inside is supported at a predetermined interval, the compressive force does not disperse over the entire area of the surface. If it is a location that is local and corresponds to a space other than the supporting column, there is a possibility that it will be deformed relatively easily.

The present invention has been made in view of the above circumstances, and has high strength against changes in internal pressure and compression from the outside, and can efficiently perform heat transport and cooling, and can be easily manufactured. It is intended to provide a mold heat pipe.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a flat heating section, a heat radiating section separated from the heating section, a heating section and a heat radiating section. A plate-type heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a container formed in a hollow flat shape by a side wall portion connecting the respective peripheral portions to each other over the entire circumference. A wick member is provided on the entire surface serving as the heating section inside the container, and a space portion inside the container is filled with a shape retaining member having a porous structure that retains the shape of the heat pipe. It is a feature.

Further, the shape holding member is joined and fixed to the inner peripheral surface of the container.

Therefore, according to the plate type heat pipe of the present invention, since the inside thereof is filled with the shape holding member as the holding material, the entire surface of the heating section and the heat radiating section comes into contact with the shape holding member. Therefore, the entire inner surface is substantially uniformly supported by the shape retaining member, and when the heat pipe is not operated, even when the internal pressure is a vacuum pressure, the thickness direction, that is, the heating unit and the heat radiating unit approach each other. The compressive strength in the direction becomes higher than before. In addition, even when the internal pressure rises due to the phase change of the working fluid during the heat pipe operation, the entire area of the heating and radiating surfaces of the container receives the force almost uniformly. It acts in a distributed manner over the entire area, and its force is absorbed as tensile stress of the shape holding member filled inside the container, so that the strength against deformation of the container is increased. Furthermore, even when a compressive force is applied from the outside, the force from the outside can be dispersed over the entire surface, so that deformation of the container due to the compressive force can be prevented.

Further, since the shape maintaining member has a porous structure and its pores serve as a vapor flow path, the flow resistance there is not so high, and the cooling efficiency of the heat pipe is not reduced. Absent.

Further, a wick member is provided on at least the inner surface of the container which is to be the heating section.
The liquid-phase working fluid refluxed from the heat radiating portion is diffused and held almost uniformly over the entire inner surface of the heating portion by the capillary pressure of the wick on the inner surface of the heating portion.

Therefore, a required amount of the liquid-phase working fluid is reliably supplied to the inner surface of the heating section which becomes the evaporating section. The working fluid that has returned to the heating unit side has the liquid-phase working fluid diffused almost uniformly over the entire inner surface thereof by the capillary pressure of the wick member disposed on the heating unit side, and again turns into steam to retain the shape holding member. Flows to the heat radiating portion side through which the heat is radiated and condensed into a liquid phase. In addition, since the shape maintaining member has a porous structure, a sufficient steam flow path can be secured in the pores.

Further, if the shape holding member is joined and fixed to the inner peripheral surface of the container, it can cope with a sudden change of the internal pressure accompanying the phase change of the working fluid, that is, even when the internal pressure is large. Since the force for expanding the shape holding member filled with the shape of the heat pipe therein acts as a tensile stress, if the shape holding member is within the allowable tensile stress, the expansion force can be suppressed. Thus, the shape of the heat pipe can be maintained.

In the case of the plate-type heat pipe of the present invention, since the wick and the shape holding member may be built in the container after the container is formed, the forming of the heat pipe is easier than before. As a result, it can be easily manufactured.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plate type heat pipe 9 according to the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a plate-type heat pipe 9 according to the present invention.
The shape of the container 10 is a hexahedron composed of rectangular surfaces.

More specifically, as an example, a heating section 11 having a rectangular flat surface, a heat radiating section 12 having a rectangular flat face and spaced apart from the heating section 11, The container 10 is a metal hermetically sealed container made of copper or the like formed by the rectangular side wall 13 connected to the heating unit 11 over the entire circumference. The container 10 can be formed by a general appropriate means such as extrusion molding. A predetermined amount of a condensable fluid such as pure water or alcohol is sealed in the container 10 as a working fluid (not shown) in a vacuum degassed state.

The heating unit 11 inside the container 10
The wick 14 is provided on the entire flat inner surface. The wick 14 is for dispersing and distributing the liquid-phase working fluid almost uniformly over the entire inner surface of the heating unit 11 by the capillary pressure there.

The wick 14 may be any of ceramics, metals, cermets or the like mixed with them, but is itself excellent in thermal conductivity and heat resistance and can be used in contact with a working fluid for a long period of time. Those which do not react and have good wettability of the working fluid are preferable. Further, as an example, a metal mesh attached or a copper powder sprayed on the inner surface by, for example, plasma spraying can be used.

Further, the hollow portion inside the container 10 is filled with a porous shape retaining member 15, and is fixed to the inner peripheral surface of the container 10 by appropriate means such as heat welding or bonding with an adhesive. ing. The shape holding member 15 has a coarse porous structure having pores, is set to have a high porosity to the extent that a vapor flow path can be secured, and does not increase the flow resistance of the working fluid vapor there. It has a coarse porous structure in which large pores are formed.

That is, the pores of the shape holding member 15 form a vapor flow path for the gas-phase working fluid heated by the heating unit 11.

The shape holding member 15 used here
As in the case of the wick 14, any of ceramics, metals, and cermets containing a mixture thereof may be used. However, even if the wick 14 itself is excellent in heat conductivity and heat resistance, and is in contact with a working fluid for a long period of time, Those that do not react are preferred. As the shape holding member 15, for example, a coarse mesh, a coarse sintered material, or the like can be adopted.

The plate type heat pipe 9 having the above-described structure is electrically connected to a predetermined portion of a circuit formed on a printed circuit board.
The heating unit 11 (lower surface) is attached to the upper surface of a member to be cooled (not shown) such as U so as to be in close contact with the upper surface.

Note that a large number of radiating fins 16 may be provided on the outer surface of the radiating section 12 as shown in FIG. Further, as shown in FIG. 3, the flat surface of the heat radiating portion 12 may be formed as an uneven surface 17 to increase the heat radiating area.

Next, the operation of the plate-type heat pipe 9 configured as described above will be described.

When a member to be cooled such as an electronic device generates heat,
The heat is transmitted to the lower heating unit 11 in contact with the member to be cooled of the plate-type heat pipe 9. Then, the working fluid stored at the bottom of the container 10 is heated and evaporated. Therefore, the inner surface of the heating unit 11 is an evaporating unit. In this case, since the shape holding member 15 is joined and fixed to the inner peripheral surface of the container 10 by appropriate means such as heat welding, the force acting on the container 10 due to the increase in the internal pressure of the container 10 is reduced. 15, the force acting on the container 10 is absorbed as the tensile stress of the shape holding member 15, so that the shape of the container 10 is reliably held.

The working fluid that has become steam flows toward the low-temperature heat radiating section 12 through the pores of the shape holding member 15 that becomes a steam flow path, and is deprived of heat on the inner surface of the heat radiating section 12 to be condensed. . That is, the vapor of the working fluid transports the heat generated by the member to be cooled as latent heat of vaporization, and the heat of the member to be cooled is released when the working fluid in the gaseous phase condenses in the radiator 12. Therefore, the inner surface of the heat radiating portion 12 is a condensing portion as the plate-type heat pipe 9. Further, the heat of the cooling target member transported to the heat radiating section 12 in the state of the latent heat of vaporization of the working fluid is radiated from the heat radiating section 12 to the outside.

On the other hand, the working fluid which has condensed and becomes a liquid phase again is transported to the inner wall surface side of the heating unit 11 via the shape holding member 15 and the side wall 13 which are in contact with the inner surface of the heat radiating unit 12.

The liquid-phase working fluid that has returned to the heating unit 11 via the pores of the shape holding member 15 and the side wall of the container is applied to the entire inner surface of the heating unit 11 by the capillary pressure of the wick 14 on the inner surface of the heating unit 11. Are almost equally diffused and retained.

Then, the working fluid supplied to the heating unit 11 is heated again and evaporates, and by continuing the same cycle as the above-mentioned cycle, the heat of the member to be cooled is satisfactorily transported, and the member to be cooled is cooled. 15 is cooled.

The plate-type heat pipe 9 is
Since the shape holding member 15 is provided in the entire interior of the container 10, the heating unit 11 and the heat radiating unit 12 are supported from the inside, and the inside of the plate-type heat pipe 9 is in a vacuum state, that is, the plate-type heat pipe 9 The heating unit 11 and the heat radiating unit 12 are
Deformation such as being depressed in the thickness direction of 0 is prevented,
Deformation does not occur even with external compression. Further, as described above, since the shape holding member 15 is joined and fixed to the inner peripheral surface of the container 10 by appropriate means such as heat welding, the container accompanying the rise in the internal pressure of the container 10 when the plate-type heat pipe 9 is operated. Deformation such as swelling in the thickness direction is reliably absorbed as tensile stress of the shape holding member 15, so that deformation of the container 10 does not occur. That is, the container 10 is prevented from being deformed in the thickness direction.

In the above embodiment, the wick 14 is provided in the heating section 11 inside the container 10 and is provided in two layers from the outer wall in the thickness direction. However, the present invention is not limited to this. May be provided.

[0043]

As is apparent from the above description, according to the present invention, since the inside of the container of the plate-type heat pipe is filled with the porous shape-holding member, the shape-holding member is heated and radiated. Can be supported almost as a surface,
Deformation during non-operation and further deformation due to external compression can be prevented more reliably than before.

Further, since the shape holding member has a rough porous structure, the flow resistance in the central portion inside the container does not increase, and a sufficient steam flow path can be secured in the pores of the shape holding member. Furthermore, since the wick is provided on the inner surface of the heating unit, the working fluid in the liquid phase is diffused and held almost uniformly over the entire inner surface of the heating unit by the capillary pressure of the wick. That is, with the above configuration, the plate shape of the heat pipe can be maintained, and the heat pipe performance can be maintained or improved.
Since the heat source, that is, the member to be cooled can be efficiently cooled, the cycle of evaporating and condensing the working fluid becomes active, and the liquid-phase working fluid can be dispersed over the entire surface of the heating section at a high capillary pressure. Even if the amount of heat of the heat source is large, heat can be efficiently transported and sufficiently cooled.

Furthermore, if the shape holding member is joined and fixed to the inner peripheral surface of the container, the shape holding member can reliably absorb deformation such as bulging in the thickness direction of the container due to an increase in internal pressure as tensile stress. Container shape can be maintained.

Further, when manufacturing the plate-type heat pipe of the present invention, it is only necessary to provide a wick or a shape holding member inside after forming the container, and it is easy to make the heat pipe. The heat pipe can be manufactured more easily than in the past.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a plate-type heat pipe of the present invention.

FIG. 2 is a schematic sectional view showing an example of a state in which fins are attached to the upper surface of the heat pipe.

FIG. 3 is a schematic cross-sectional view showing an example of a heat pipe of the present invention using a container whose surface serving as a heat radiating portion has an uneven shape.

FIG. 4 is a schematic sectional view showing an example of a section of a conventional heat pipe.

FIG. 5 is a schematic cross-sectional view showing an example when a conventional heat pipe is deformed.

FIG. 6 is a schematic sectional view showing an example of a section of a conventional heat pipe.

[Description of Signs] 9: heat pipe, 10: container, 11: heating unit, 12: heat radiating unit, 13: side wall, 14: wick, 15: shape holding member.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 7/20 H05K 7/20 R (72) Inventor Yuji Saito 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd.

Claims (2)

[Claims] 1. A flat heating section, a heat radiating section isolated to face the heating section, and a side wall section connecting peripheral edges of the heating section and the heat radiating section to each other over the entire circumference. In a plate-type heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a hollow flat container, a wick member is provided on the entire surface of the surface serving as the heating section inside the container. At the same time, in the space inside the container,
A plate-type heat pipe filled with a shape holding member having a porous structure for holding the shape of the heat pipe. 2. The plate-type heat pipe according to claim 1, wherein the shape holding member is fixedly joined to an inner peripheral surface of the container.