JPH11325765A - Heat pipe and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pipe wherein a plate thickness is decreased as much as possible by removing a wick material and to provide manufacture thereof. SOLUTION: A heat pipe is formed that by a latent heat generated when working liquid deaerated and sealed in the internal part of a closed hollow body is alternately changed to a liquid phase and an air phase, heat is transmitted from one end to the other end. By processing the inner surface of a hollow body 7, a coarse surface 7c is formed. In a manufacturing method, the coarse surface 7c is formed such that the inner surface of the hollow body 7 is rubbed by rigid granulated substance to effect polishing processing or chemical corrosion treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat pipe and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a heat pipe is a type of heat transfer element for efficiently transferring heat, and a working fluid such as water and its vapor and a wick for refluxing the working fluid are sealed in a closed container. Have been. The wick is formed of a bundle of thin wires or a wire mesh, and can flow a liquid into the wick by capillary action.

When heat is applied to one end of a heat pipe,
The working fluid around the heating unit evaporates, and the generated steam flows through the heat pipe toward the other end having a lower temperature. The transferred steam comes in contact with the wick and releases the evaporation temperature and latent heat to condense. The condensed working fluid is conveyed by the wick toward the heating section. In such a cycle, the heat pipe can perform heat transfer, and can be used for, for example, radiating heat locally at various locations in various devices.

[0004] The heat pipe can take various shapes. However, when the heat pipe is built in for heat radiation inside the electronic device, it is hard to hinder the miniaturization and thinning of the electronic device, and the heat pipe has a large area. In general, a thin heat pipe with a plate-like thickness is used because it can exert an effect.
One example is shown below with reference to FIGS. 4A and 4B (Japanese Patent Publication No. 54-15342). In the figure, (1) is a plate-shaped hollow body (outer shell material), (2) is a wick material, and (3) is a reinforcing column. The plate-shaped hollow body (1) is a pair of thin metal plates (1a) and (1b) made of silver, copper, or the like, opposed to each other with a small gap therebetween, and hermetically bonded by pressing the peripheral portion. . An airtight space (4) serving as a vapor passage is formed therein, and the space (4) is degassed and a working fluid such as alcohol is sealed therein. The wick material (2) is made of cotton gauze, metal fiber or the like coated on the inner surface of the plate-shaped hollow body (1), increases the surface area of the plate-shaped hollow body, promotes evaporation of the working fluid in the heating unit, and The working fluid is returned from the cooling unit to the heating unit by capillary force.

The pillar (3) is a hollow pillar having a sealed structure interposed between a pair of thin plates (1a) and (1b) of the plate-like hollow body (1). The plate-like hollow body (1) withstands atmospheric pressure. Reinforce to prevent deformation. A wick material (2a) similar to the above-mentioned wick material (2) is coated on the inner surface of the support, and
The space (4a) is degassed, and a working fluid such as alcohol is sealed inside.

According to the above configuration, at one end (heating portion) of the plate-shaped heat pipe (5), the working fluid takes heat from the external high-temperature body and the evaporation is promoted by the wick material (2) as described above. It vaporizes and moves to the other end (cooling unit) through the hollow part of the heat pipe (5). In the cooling section, the working liquid vapor is cooled by the external low-temperature body and condensed, and the condensed liquid returns to the heating section in the wick material (2) by capillary action.
At this time, the strut (3) interposed between the two thin plates (1a) and (1b) of the plate-shaped hollow body (1) also has a heat pipe structure, and therefore, one thin plate (1a) of the plate-shaped hollow body (1). Is heated by the support (3) even if a part of
b) is also quickly transmitted, and heat is uniformly transported to both thin plates (1a) and (1b).

[0007]

According to the plate-shaped heat pipe (5), since the wick material (2) is coated on the inner surface of the plate-shaped hollow body (1), the plate thickness is increased accordingly. Therefore, there is a problem that there is a limit in reducing the thickness and weight. When silver or copper is used for the plate-like hollow body (1) due to heat transfer and corrosion resistance, weight reduction becomes more difficult.

An object of the present invention is to provide a heat pipe in which the wick material is removed and the plate thickness is reduced as much as possible, and a method for manufacturing the same.

[0009]

SUMMARY OF THE INVENTION The present invention provides a heat pipe as a heat pipe, wherein the working fluid degassed and sealed in a closed hollow body is caused by latent heat when alternately changing into a liquid phase and a gas phase. A heat pipe for transferring heat from one end to the other end, characterized in that the surface of the hollow body is processed to form a rough surface, and as a manufacturing method, the rough surface of the surface of the hollow body is It is characterized in that it is formed by rubbing with a hard granular material or polishing or chemically corroding.

According to the above construction, the surface of the hollow body is machined to form a rough surface directly on the hollow body and replace the existing wick material.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat pipe and a method for manufacturing the same according to the present invention will be described below with reference to FIGS. The feature of the present invention is that the inner surface of the hollow body in which the working fluid of the heat pipe is degassed and sealed is processed to form a rough surface, thereby eliminating the need for a conventional wick material and making the heat pipe thinner. And weight reduction becomes possible.

FIG. 1 is a partial sectional side view of a plate-like heat pipe (6) according to the present invention, in which (7) is a plate-like hollow body, (8) is a hole, and (9) is a heat shrink. (10) is a connecting member, and (11) is a mounting screw.

The plate-shaped hollow body (7) is a hollow body in which a pair of aluminum thin plates (7a) and (7b) having a plate thickness of 0.5 mm are opposed to each other with a small interval therebetween to form front and rear surfaces, and the peripheral edges thereof are hermetically connected. It is. A rough surface (7c) is formed on the inner surface thereof, and an airtight space (1
2) is formed, and the inside of the space (12) is evacuated, and a working fluid such as water or alcohol is sealed therein.

At this time, since water has a larger heat capacity than alcohol and is suitable for mass heat transfer, it is preferable to use water as the working fluid. Further, when the plate-shaped hollow body (7) is made of aluminum, the weight can be further reduced. At this time, the rough surface (7c) is nickel-plated (about 20 μm thick) so that the inner surface of the aluminum plate-shaped hollow body (7) is not corroded by water, and then copper is evaporated to prevent pinhole corrosion. , Durability and corrosion resistance are enhanced.

In forming the hermetically sealed structure of the peripheral portion of the hollow body, as shown in FIG. 2, first, a flange portion formed by forming the peripheral portion of the front thin plate (7a) into a step shape over the entire circumference is formed. A heat-shrinkable resin (13) such as Teflon is fitted over (7d) over the entire periphery. Next, the back side thin plate (7
The periphery (7e) of b) is folded back in a U-shape so as to enclose the resin (13), and pressed to compress the resin (13). Thereafter, when the resin (13) is heated and shrunk, the resin (1) is shrunk.
The thickness of 3) is increased, and the periphery of the hollow body is hermetically sealed without any gap.

As shown in FIG. 1, the holes (8) are formed in the recesses (7f) and (7g) projecting inward from the mounting portions of the thin plates (7a) and (7b) on the mounting surface. It is formed through. The washer (9) is made of a heat-shrinkable resin, for example, Teflon having a diameter of 8 mm and a thickness of 0.2 mm and having the same hole diameter as the hole (8), and each recess (7f) between the front and back thin plates (7a) and (7b). ) (7g) and inserted continuously with the hole (8). When the Teflon is heated at about 150 ° C,
The one having a thickness of 0.2 mm is thermally contracted and becomes thick to about 0.3 mm.

The connecting member (10) is a bolt member (10) having a mounting screw insertion hole (10aa) penetrating in the axial direction.
a) and its nut member (10b), and the flange portion of the bolt member (10a) and the outer peripheral corners of the nut member (10b) are chamfered and knurled (R) for tightening.
To form Then, the bolt member (10a) is inserted from below through the hole (8) through the washer (9), and the nut member (10b) is screwed into the male screw portion of the bolt member (10a) on the front side, and from above. The bolts and nuts (10a) (10b) are tightly tightened with a knurling-specific fastening jig. Next, when the washer (9) is heated, since the Teflon is slippery, it is easily thermally contracted, the thickness of the washer (9) increases, the gap between the thin plates (7a) and (7b) disappears, and the plate-like hollow body ( The pair of thin plates (7a) and (ab) of the front and back of 7) are airtightly connected to each other at a plurality of locations.

Since the bolt member (10a) and the nut member (10b) are extremely thin and strongly tightened, the screw cannot be used or the brim portion is damaged. Therefore, appropriate quenching and annealing are necessary, and the steel member is made of steel. It is desirable to finish plating. Thereby, the bolt member (10a) and the nut member (10b)
The elastic repulsive force increases, and when tightened, it elastically expands to increase the tightening force. Further, at the time of manufacturing, the Teflon of the hollow body peripheral portion and the connecting portion may be simultaneously heated at about 150 ° C. as a whole.

In this way, an airtight structure is formed, and by being joined at a plurality of places, it is hard to be crushed even if it is thin, and it becomes hard to bend because of increased bending rigidity, and is mechanically reinforced. Then, the mounting screw (11) is inserted into the screw insertion hole (10aa), and the plate-shaped heat pipe (6) is mounted on the mounting surface of the electronic device or the like.

The operation of the present invention based on the above configuration will now be described. First, the inside of the plate-shaped hollow body (7) shown in FIG. 3 is degassed by using a working liquid injection port (7h), and then a working liquid such as water is injected therefrom, and the mounting screw (11) is used. A plate heat pipe (6) is attached to the surface to be attached. Therefore, at one end (heating portion) of the plate-shaped heat pipe (6), the working fluid takes heat from the external high-temperature body and evaporates, passes through the space (12) of the plate-shaped heat pipe (6), and ends at the other end ( Cooling unit).

At this time, the rough surface (7c) increases the surface area of the hollow body to promote the evaporation of the working fluid. In the cooling section, the working fluid vapor is cooled by the external low-temperature body and condensed. Reflux to the heating section by capillary action of the rough surface (7c). That is, the rough surface (7) formed on the inner surface of the plate-like hollow body (7)
By (c), the evaporation of the working fluid is promoted, and the condensate is refluxed. Therefore, the wick material (2) (see FIG. 4) for coating the inner surface of the plate-shaped hollow body (7) becomes unnecessary, and the thickness and weight of the plate-shaped heat pipe (6) can be reduced. Also, since the plate-like hollow body (7) is made of aluminum,
The weight is further reduced.

Next, in the manufacturing method of the present invention, the rough surface (7
In the formation of c), first, the inner surface of the plate-like hollow body (7) is rubbed with a hard granular material, for example, fine sand, alumina (GC) powder, or the like, and is polished to physically give a rough surface (about 150 mesh). 7c) is formed. Alternatively, the inner surface is chemically etched (etched) to form a rough surface (7c). And
When aluminum and water are used as the plate-like hollow body (7) and the working fluid, respectively, the rough surface (7c) is nickel-plated and copper-deposited as described above.

In the above embodiment, a plate-shaped heat pipe has been described. However, the present invention is not limited to this. The present invention can also be applied to a heat pipe in which a working fluid is degassed and sealed in a sealed pipe. A rough surface may be formed by a chemical corrosion treatment.

[0024]

According to the present invention, one end of the hollow body is moved from one end to the other end by latent heat when the working fluid degassed and sealed in the closed hollow body alternately changes into a liquid phase and a gas phase. In the heat pipe that transfers heat, the surface of the hollow body is processed to form a rough surface, so that a wick material for coating the surface of the hollow body is not required, and the heat pipe can be made thinner and lighter. Further, by forming the hollow body with aluminum, the heat pipe can be further reduced in weight. Also, since a pair of thin plates forming a plate-shaped hollow body in the plate-shaped heat pipe were mechanically connected at a plurality of locations by a cylindrical member,
Even if it becomes thin, it is hard to be crushed and hard to bend, and is mechanically reinforced.

[Brief description of the drawings]

FIG. 1 is a sectional side view of a main part showing an embodiment of a plate heat pipe according to the present invention.

FIGS. 2A and 2B are a plan view and a side view showing a sealing structure of a peripheral portion of a plate-like heat pipe according to the present invention.

FIGS. 3A and 3B are a plan view and a side view showing an embodiment of a plate heat pipe according to the present invention.

FIGS. 4A and 4B are a perspective view and a partial cross-sectional side view showing a conventional example of a plate-like heat pipe.

[Explanation of symbols]

 Reference Signs List 6 plate heat pipe 7 plate hollow body 7c rough surface 8 hole 9 washer 10 connecting member

Claims (5)

[Claims] 1. A heat pipe for transferring heat from one end of a hollow body to the other end by latent heat when a working fluid degassed and sealed in a closed hollow body alternately changes between a liquid phase and a gas phase. 2. The heat pipe according to claim 1, wherein the surface of the hollow body is processed to form a rough surface. 2. The hollow body is a plate-like hollow body in which the peripheral edges of a pair of front and back metal thin plates facing each other at a small interval are hermetically connected, and a predetermined mounting surface of the plate-like hollow body. A plurality of attachment portions to the pair of thin plates, a hole formed by penetrating the recess formed in a direction approaching each other from front to back, and a hole matching the hole, and between the front and back thin plates. A heat-shrinkable resin washer having a predetermined thickness inserted so as to be sandwiched by the concave portion, and a coupling member for inserting a bolt member having a mounting screw insertion hole penetrating in the axial direction into the hole portion and tightening with a nut member. After tightening with the connecting member,
2. The heat pipe according to claim 1, wherein the washer is heat-shrinked to increase its thickness, and a pair of front and back thin plates are connected to each other at a plurality of locations in an airtight manner. 3. The heat pipe according to claim 1, wherein the hollow body comprises a hermetically sealed tube. 4. The heat pipe according to claim 1, wherein the rough surface of the surface of the hollow body is formed by rubbing the inner surface with a hard granular material or by performing a chemical corrosion treatment. Manufacturing method. 5. The method according to claim 2, wherein an inner surface of the aluminum plate-shaped hollow body is polished or chemically corroded to form a rough surface, and then the rough surface is nickel-plated and copper is vapor-deposited. A method for manufacturing a plate-like heat pipe.