JPH0634284A - Tabular heat pipe - Google Patents

Abstract

PURPOSE:To obtain a tabular heat pipe which is capable of planar (two dimensional) heat transfer. CONSTITUTION:At least in one of the inner walls 9 bounding a hermetically closed flat space 6 inside a disk-shaped container 7 a multiplicity of minute grooves 8 or a device for inducing capillary action is provided so that in the flat space 6 with sides of minute grooves 8 or a device for inducing capillary action a working fluid can circulate in a planar flow and heat can freely be transferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar heat pipe for performing a planar (two-dimensional) heat transfer from a heat source.

[0002]

2. Description of the Related Art In the first place, a heat pipe encloses a medium called a "working fluid", which easily changes between a gas phase and a liquid phase, inside a sealed pipe, and the latent heat at the time of the phase change is used as an intermediary flow. Is a device for transporting heat (Oshima, Matsushita, Murakami "Heat Pipe Engineering" Asakura Shoten).

Therefore, the working fluid in the pipe takes heat from the surroundings on the high temperature side and evaporates to become a working fluid in a vapor phase state and flows to the low temperature side. Then, on the low temperature side, heat is released to the surroundings to change from the gas phase state to the liquid phase state. The working fluid that has released heat and has become a liquid phase is returned to the high temperature side mainly by utilizing the capillary phenomenon. In this way, the working fluid circulates between the high temperature side and the low temperature side while undergoing a phase change, and the heat on the high temperature side of the heat pipe can be transported to the low temperature side.

Conventionally, this type of heat pipe, as the name implies, is basically constructed so that the working fluid flows along the axis of the pipe, so that it is linear along the heat pipe. Only (one-dimensional) heat transfer was possible, and heat transfer having a two-dimensional (two-dimensional) spread was impossible.

Such a conventional heat pipe is shown in the drawings. 13 to 16 are views showing an arrangement example of a conventional heat pipe that performs linear heat transfer, and FIG. 13 is a plan view showing an arrangement example of the heat pipe when there is one heat generating component. FIG. 14 is a sectional view taken along line XIV-XIV in FIG.
FIG. 15 is a plan view showing an arrangement example of heat pipes when there are three heat generating components, and FIG. 16 is a sectional view taken along line XVI-XVI in FIG.

In the figure, 1 is a circuit case in which a circular circuit accommodating recess 1a for accommodating a circuit is recessed, 2 is a circuit board fixed to the bottom surface 1b of the circuit accommodating recess 1a with screws 3, and 4 is a circuit board 2
The heat-generating components 5 mounted above are heat pipes that perform conventional linear heat transfer.

In the conventional heat pipe 5, for example, in a plane such as the circuit board 2 of the electronic device, when the heat of the heat generating component 4 is to be uniformly released to the outer peripheral wall portion 1c of the circuit case 1, As shown in FIGS. 13 and 14, it is necessary to radially arrange a plurality of heat pipes 5 between the heat generating component 4 and the cooling portion of the outer peripheral wall portion 1c of the circuit case 1.

When a plurality of heat-generating components 4 are mounted on the same circuit board 2, as shown in FIGS. 15 and 16, the individual heat-generating components 4 and the outer peripheral wall portion 1c of the circuit case 1 are mounted.
It was necessary to separately arrange the heat pipes 5 between them.

[0009]

In recent years, electronic devices such as electronic computers and communication devices have made remarkable progress, and are being accelerated more and more by the development of large-scale integrated circuit technology and optical technology. However, in such an electronic device, heat generation sources are concentrated, which is a major problem in circuit mounting.

Also, although optical technology is widely used,
The characteristics and life of optical components such as semiconductor lasers have great temperature dependence. Therefore, for integrated circuits and some optical components,
It is necessary to implement a circuit mounting technique that takes heat dissipation into consideration so that the temperature does not exceed a certain temperature. However, as in the conventional example, a large number of heat pipes 5 are arranged to cover the opening area of the circuit accommodating recess 1a. In the case of arrangement, it is necessary to fully consider the influence of this on the electrical characteristics and temperature dependence, and there was a problem that the design constraint becomes large.

In view of the above-mentioned problems of the conventional technique, the present invention does not perform linear (one-dimensional) heat transfer like the conventional heat pipe, but planar (two-dimensional).
It is intended to provide a flat heat pipe capable of performing efficient heat transfer.

[0012]

The above-mentioned problems can be solved by the present invention by adopting the novel characteristic construction means listed below. That is, a first feature of the present invention is to provide a plurality of grooves on at least one side surface of an inner wall that defines a flat space inside a container, and the working fluid is planarly distributed across the groove group and the flat space. It is a planar heat pipe that can freely circulate heat.

A second feature of the present invention is a flat heat pipe in which the plurality of grooves in the first feature are mesh-shaped.

A third feature of the present invention is that a capillary action inducer is attached to at least one side surface of an inner wall that defines a flat space inside a container, and the capillary action inducer and the flat space are covered. It is a flat heat pipe in which the working fluid is made to circulate and transfer heat in a planar manner.

A fourth feature of the present invention is a flat heat pipe in which the capillary phenomenon inducer of the third feature is composed of a fibrous substance.

[0016]

Since the present invention employs the above-described constitutional means, it is in a liquid phase state by a plurality of grooves or capillarity inducers provided on at least one side surface of the inner wall of the flat space sealed inside the container. Of the working fluid can be moved in a plane, and the working fluid can be refluxed between any points on the plane in the sealed container. On the other hand, the working fluid in the vapor phase can move between arbitrary points in the plane through the space in the closed container. As a result, the present invention makes it possible to transfer heat between the planes connecting the arbitrary heat generation points and the arbitrary heat absorption points.

[0017]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of the flat heat pipe of this embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG. In the figure, α
Is a flat heat pipe of this embodiment, 6 is a flat space that is hermetically defined inside the disk container 7, and 8 is a net-like fine groove formed on the entire inner wall surface 9 of the flat space 6 facing each other. . The same members as those in the conventional example are designated by the same reference numerals.

The flat heat pipe α of the present embodiment is a mesh-like structure which allows the working fluid to flow back to the inner wall surface 9 of the flat space 6 in the closed disk-shaped container 7 by utilizing the capillary phenomenon. The groove 8 is engraved.

The specification of the present embodiment is such a concrete embodiment, and FIGS. 3 and 4 are explanatory views of the operating principle of the planar heat pipe α of the present embodiment. In the figure, A is a heat generation point, B is a heat absorption point, 10 is an arrow showing the flow of the working fluid in the vapor phase, and 11 is an arrow showing the flow of the working fluid in the liquid phase.

In FIG. 3, it is assumed that there are one exothermic point A and one exothermic point B. Exothermic point A
In the vicinity, the working fluid evaporates and enters the gas phase,
A flow of the working fluid as indicated by a thick arrow 10 is created. Then, it is cooled in the vicinity of the endothermic point B to be in a liquid phase state.

The working fluid in the liquid phase state has a plurality of fine mesh-like grooves 8 formed on the inner wall surface 9 of the flat space 6 of the disk-shaped container 7 of the flat heat pipe α. ,
Due to the capillary phenomenon, the endothermic point B is returned to the exothermic point A where the working fluid in the liquid phase is small, so that a flow as indicated by a thick arrow 11 is created. As a result of such an operation, heat is continuously transferred from the heat generating point A to the heat absorbing point B.

In FIG. 4, there is one exothermic point A and endothermic point B.
Is assumed to be the entire outer peripheral portion of the disk container 7 of the flat heat pipe α. Therefore, the endothermic point B is not specified. In the case of FIG. 4, the working fluid recirculates between the heat generating point A and the heat absorbing point B of the entire outer peripheral portion of the planar heat pipe α by the operation as indicated by arrows 10 and 11, and heat is transferred. The same operation is performed when there are a plurality of heat generation points A.

(Embodiment 2) A second embodiment of the present invention will be described with reference to the drawings. 5 is a side view of the flat heat pipe of this embodiment, and FIG. 6 is a sectional view taken along line VI-VI in FIG.
In the figure, β is the flat heat pipe of this embodiment, 7 is the flat heat pipe β, the flat space 6 inside the disk container 7, and the inner wall surface 9
The grooves are concentric circles and radial grooves engraved on the entire surfaces facing each other.

In this embodiment, instead of the innumerable mesh-shaped grooves 8 of the first embodiment, grooves 8'combined with concentric circles and radials are formed. Therefore, it is suitable for releasing the heat at the heat generation point near the center of the flat heat pipe β to the heat absorption point at the outer peripheral portion of the disk container 7.

In the above-mentioned first embodiment and this embodiment, the shape of the planar heat pipes α and β is disc-shaped, but it goes without saying that there is no particular restriction on the outer shape. That is. Also, the inner wall surface 9
The engraved shapes of the grooves 8 and 8 ′ are not limited to the engraved shapes of the first embodiment and this embodiment, and any engraved shape can be used as long as the working fluid can move in a plane. It goes without saying that carved shapes can also be used.

(Embodiment 3) A third embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a side view of the planar heat pipe of this embodiment, and FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. In the figure, γ is a planar heat pipe of this embodiment, 12
Is a cloth as a capillarity inducer attached to both sides of the inner wall surface 9 of the flat space 6 inside the disk container 7 of the flat heat pipe γ of this embodiment.

However, the specifications of the present embodiment are such a specific embodiment that the liquid phase state is obtained by utilizing the capillary phenomenon caused by the cloth 12 attached to the inner wall surface 9 of the flat space 6. Recirculate the working fluid of. Specifically, the cloth 12
Within the range where is attached, the working fluid in the liquid phase can flow and recirculate in any direction from the position of any heat generation point.

In this embodiment, similar to the first and second embodiments, the planar heat pipe γ whose outer shape is a disk shape is shown, but the outer shape is not limited to the disk shape. Absent. Further, the cloth 12 which is a capillarity inducer attached to the inner wall surface 9 may be a net or the like as long as the working fluid can flow in a planar manner by the capillarity. Further, regarding its material, in consideration of the operating temperature range, the characteristics of the working fluid, the compatibility with the sealed container 7, etc., various materials such as chemical fiber, plant fiber, animal fiber, glass fiber, metal fiber, carbon fiber, etc. can be used. It can also be composed of fibrous material.

(Application Example) FIGS. 9 to 10 are plan views showing an example in which the planar heat pipes α and β are applied to the cooling of the circuit board of an actual electronic device, and FIG. 9 is a sectional view taken along line X-X. 11 to 12 are plan views and FIG. 11 showing an example in which the planar heat pipe γ is applied to the cooling of the circuit board of the electronic device.
It is an XII-XII sectional view taken on the line in FIG.

Compared with FIGS. 13 to 14 showing a conventional example having a plurality of heat generating components 3, in the conventional heat pipe, between the heat generating components 4 and the cooling portion existing on the outer periphery of the circuit case 1. It was necessary to arrange a large number of heat pipes 5, but by applying the planar heat pipes α, β, γ of the present invention, the flat space 6 formed integrally in the bottom 1d of the circuit case 1 By the grooves 8 and 8'provided on the wall surface 9 and the cloth or the like, it is possible to achieve efficient cooling and labor saving by reducing the number of constituent parts.

[0031]

As described above, according to the present invention,
Compared with the prior art in which a large number of conventional heat pipes that perform linear (one-dimensional) heat transfer are provided, planar (two-dimensional) heat transfer is possible, so the heat dissipation structure can be simplified.

Therefore, when it is applied to an electronic device or the like, it is particularly effective in improving the efficiency of heat transfer, and regardless of the position of the heat generating component on the circuit, heat can be easily dissipated by one flat heat pipe, and the heat dissipating structure can be achieved. It is not necessary to consider the interference with the circuit design, the burden on the circuit design is lightened, and the design work is facilitated. Therefore, even a large-scale and high-power-consumption integrated circuit, a device using an optical component, or the like, has a small size, high reliability, and can be easily realized.

[Brief description of drawings]

FIG. 1 is a side view of a flat heat pipe according to a first embodiment of the present invention.

2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an explanatory view of the principle of the flat heat pipe of the present invention, and is an explanatory view in the case where there is one heat generation point.

FIG. 4 is an explanatory diagram of the case where there are a plurality of heat generation points.

FIG. 5 is a side view of the flat heat pipe according to the second embodiment of the present invention.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is a side view of a flat heat pipe according to a third embodiment of the present invention.

8 is a sectional view taken along line VIII-VIII in FIG. 7 of the above.

FIG. 9 is a plan view showing an example in which the first and second embodiments of the present invention are applied to cooling a circuit board of an electronic device.

FIG. 10 is a sectional view taken along line XX in FIG.

FIG. 11 is a plan view showing an example in which the third embodiment of the present invention is applied to cooling a circuit board of an electronic device.

12 is a sectional view taken along line XII-XII in FIG.

FIG. 13 is a plan view showing an arrangement example of a conventional heat pipe that performs linear heat transfer, and is a diagram showing an arrangement example when there is one heat generating component.

14 is a sectional view taken along line XIV-XIV in FIG.

FIG. 15 is a plan view showing an arrangement example of a conventional heat pipe when the number of heat generating components is three in the same as above.

16 is a sectional view taken along line XVI-XVI in FIG.

[Explanation of symbols]

 α, β, γ ... Planar heat pipe A ... Exothermic point B ... Endothermic point 1 ... Circuit case 1a ... Circuit housing recess 1b ... Bottom 1c ... Outer peripheral wall 1d ... Bottom 2 ... Circuit board 3 ... Screw 4 ... Exothermic part 5 ... Conventional heat pipes that perform linear heat transfer 7 ... Disk container 8, 8 '... Groove 9 ... Inner wall surface 10 ... Arrow indicating the flow of working fluid in vapor phase 11 ... Flow of working fluid in liquid phase Indicating arrow 12 ... Cloth

Claims (4)

[Claims] 1. A container is provided with a plurality of grooves on at least one side surface of an inner wall that defines a flat space in a hermetically sealed manner, and a working fluid is circulated and heat-transferred in a planar manner across the groove group and the flat space. A flat heat pipe characterized by 2. The flat heat pipe according to claim 1, wherein the plurality of grooves have a mesh shape. 3. A capillary action inducer is attached to at least one side of an inner wall that defines a flat space inside a container,
A planar heat pipe characterized in that the capillary phenomenon inducer and the working fluid can circulate and transfer heat in a planar manner across the flat space. 4. The flat type heat generator according to claim 3, wherein the capillary phenomenon inducer is made of a fibrous substance.
pipe.