JPH1183360A - Finned heat pipe and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a heat pipe having low thermal resistance easily by inserting a part of the container for heat pipe into a metal cover and forming a plurality of fins being raised from the container integrally with the cover. SOLUTION: The hollow planar container 8 for a heat pipe 7 has a width shorter than the length L and the outer surface thereof is covered entirely with a cover 10 formed by solidifying molten of Al or an Al alloy. A plurality of planar square fins 11 are raised from the upper surface of the cover 10 while being arranged in parallel with each other. These fins 11 are formed integrally with the cover 10 by solidifying same molten of Al or an Al alloy as the cover 10. More specifically, the heat pipe 7 is inserted into the cover 10 provided with fins 11. According to the structure, thermal resistance between the fin 11 and the container 8 can be reduced.

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 transferring heat as latent heat of vaporization of a working fluid, and more particularly to a heat pipe in which a container and a fin are integrated and a method for manufacturing the same.

[0002]

2. Description of the Related Art As is well known, a heat pipe is obtained by enclosing a condensable fluid such as water or alcohol as a working fluid in a container (container) such as a sealed metal tube or the like that has been degassed under vacuum. The operation is performed by generating a temperature difference between both ends, and the working fluid evaporated at a high temperature flows to a low temperature part to radiate and condense, thereby performing heat transport as latent heat of the working fluid.

It is well known that a fin is attached to a heat pipe container to increase a heat radiation area or a heat absorption area to improve a heat exchange capacity. Conventionally, various means for attaching the fin to the container have been proposed. An example will be described with reference to FIG.

[0004] The heat pipe 1 shown in FIG.
Are made of a flat copper plate, and the fins 3 attached to the upper surface of the container 2 are formed by moving a plurality of flat fin bodies 4 parallel to each other from the upper surface of the flat base 5. It is a vertically erected structure and is manufactured by, for example, an extrusion molding method using aluminum as a material. The fins 3 are connected to the container 2 by bonding the lower surface of the base 5 and the upper surface of the container 2 with, for example, an epoxy-based adhesive or by soldering. Conventionally, in place of these adhesives or bonding agents, jigs such as clampers for clamping the upper surface of the base 5 and the lower surface of the container from outside have been employed.

[0005]

By the way, in the heat pipe 1 in which the fins 3 are bonded or bonded to the container 2, the adhesive and the bonding agent are connected to the container 2 and the fins 3.
Good adhesiveness is required for both. However, the epoxy adhesive and the solder are difficult to adhere to either Al or Cu, and although the lower surface of the base 5 is plated with Cu or the like, conventionally, the fin 3 is connected to the container 2. Was difficult.

On the other hand, in the heat pipe 1 in which the two are connected by a jig such as a clamper, the upper surface of the container 2 and the lower surface of the base 5 are not always kept in close contact with each other. Is formed, there is a disadvantage that the thermal resistance between the container 2 and the fins 3 is large.

The present invention has been made in view of the above circumstances, and provides a heat pipe having a small thermal resistance between a fin and a container, and a manufacturing method capable of easily manufacturing the heat pipe. It is the purpose.

[0008]

Means for Solving the Problems and Actions To achieve the above object, the invention according to claim 1 is characterized in that at least a part of the heat pipe container is cast-in with a cover made of metal and A plurality of fin portions standing upright with respect to the container are formed integrally with the cover.

Therefore, according to the first aspect of the present invention, since the container is cast-in by the metal cover,
Both are firmly connected in a state of being in close contact with each other. Since the plurality of fins are formed integrally with the cover, a heat pipe having a small thermal resistance between the fins and the container is provided. Further, since the cover and the fins are integrally formed of the same material, and no foreign matter such as an adhesive is interposed between the two, heat conduction between the two is well performed.

According to a second aspect of the present invention, at least a part of the heat pipe container is held inside a cavity having a plurality of concave portions following the shape of a fin, and then the molten metal is poured into the cavity. Injecting and solidifying to form a plurality of fins in a state of standing up from the container at the same time as casting the container, and thereafter, degassing the inside of the container to form a heat pipe. .

Therefore, according to the manufacturing method of the second aspect, since the fin is formed on the metal itself which casts the container, the thermal resistance between the container and the fin is small,
Also, the mounting strength of both is high. In the casting process, since the container is not sealed, the internal pressure of the container does not increase due to the heat of the molten metal, and the container does not deform or break.

[0012]

Next, the present invention will be specifically described. First, a specific example of the heat pipe according to the present invention will be described with reference to FIGS. The container 8 of the heat pipe 7 shown here has a hollow flat plate shape having a width W smaller than a length L. Pure water (not shown) as a working fluid is sealed in a vacuum degassed state inside the container 8 to form a heat pipe.

The container 8 is provided with an injection nozzle 9 communicating with the inside of the container. As the injection nozzle 9, a small-diameter pipe having a circular cross section made of the same material as that of the container 8 is used, and an end protruding from the container 8 is crushed in a radial direction to be sealed.

The entire outer surface of the container 8 is covered with a cover 10 formed by solidifying a molten metal of, for example, Al or an Al alloy. On the upper surface of the cover 10,
A plurality of flat rectangular fins 11 are provided in an upright state and arranged in parallel with each other. These fins 11 are formed by solidifying a molten metal of the same Al or Al alloy as the cover 10, and are formed integrally with the cover 10 by, for example, die casting. That is, the heat pipe 7 is cast inside the cover 10 having the fins 11.

Next, a method of manufacturing the heat pipe 7 provided with the fins 11 having the above configuration will be described with reference to FIG. First, a container 8 to which an injection nozzle 9 is attached is prepared, and the container 8 and the fin 11 are integrated. That is, the container 8 is accommodated in the inner space of the upper mold (movable mold) 12 and the lower mold (fixed mold) 14 in a state of being arranged substantially horizontally. The container 8 is stored with the tip of the injection nozzle 9 open to the atmosphere.

The width W of the container 8 is provided on the bottom of the upper mold 12.
A plurality of flat plate-shaped recesses 13 having the same width as are arranged in parallel with each other. In contrast, the lower mold 14
Is formed as a flat surface. In this way, the upper mold 12 and the lower mold 14 form a space (cavity) having a shape substantially following the cover 10. Lower mold 14
Is provided with a pressurizing plunger 16 configured to press a molten metal 15 of Al or an Al alloy as a material of the cover 10 from the right side to the left side in FIG.

From the above state, the pressure plunger 16 is moved in the direction of the arrow to apply pressure to the molten metal 15. Then, the entire area of the outer peripheral part of the container 8 and the intermediate part of the injection nozzle 9 are covered with the molten metal 15, and the molten metal 15 enters each concave portion 13 of the upper die 12. In this case, the melting point of Cu is higher than that of Al.
And the injection nozzle 9 does not melt.

Then, this state is left for a predetermined time,
The molten metal 15 is solidified. As a result, the plurality of fins 11
The container 8 is integrally cast into the cover 10 integrally formed with the container 8. That is, each fin 11 and the container 8 are connected to each other. Since the container 8 is not hermetically sealed at the time when the above-mentioned die casting is performed, the internal pressure of the container 8 does not increase due to the heat of the molten metal 15 and no deformation or breakage occurs.

Next, the container 8 to which the fins 11 are attached is made into a heat pipe. First, pure water (not shown) as a working fluid is injected into the container 8 through the injection nozzle 9 slightly more than a specified amount. This is because the non-condensable gas is then expelled from the container 8. As an example of this heating drive-out process, the injection nozzle 9
The container 8 is placed in a heating furnace or an oil bath (both not shown) with the container facing upward, and heated at about 120 ° C.

Then, the non-condensable gas dissolved in the working fluid is discharged from the opening end of the injection nozzle 9 to the outside of the container 8 together with the vapor of the working fluid. That is, the amount obtained by subtracting the amount expelled as steam from the total amount of the working fluid previously injected into the container 8 is the substantial sealed amount of the working fluid.

After expelling a predetermined amount of vapor, the tip of the injection nozzle 9 is crushed and sealed. As a result, the heat pipe 7 is sufficiently deaerated from the container 8 itself. In the heating drive-out step, a method in which the internal pressure of the container 8 is increased in a state where the injection nozzle 9 is temporarily fastened in advance, and then the temporarily fastened portion is opened to flush the working fluid may be adopted. Thereafter, steps such as cleaning and inspection are performed as usual. By the above procedure, the heat pipe 7 in which the fin 11 and the container 8 are firmly connected can be obtained.

As described above, according to the above specific example, since the cover 10 casts the container 8 by die casting, both can be connected in close contact with each other.
Furthermore, since the fins 11 are formed integrally with the cover 10, the heat pipe 7 having a lower thermal resistance between the fins 11 and the container 8 than in the related art can be easily manufactured.

Next, another embodiment of the present invention will be described. In the example shown here, a heat pipe configured for cooling an arithmetic processing unit of a computer will be described first with reference to FIGS. The container 8 of the heat pipe 7 has a hollow, low-height, substantially truncated quadrangular pyramid shape.

More specifically, the container 8 includes a square heating section 17, a heat-radiating section 18 which is a square about four times as large as the heating section 17 and faces in parallel above the heating section 17, This is a closed container made of copper formed by the four side surfaces and the inclined side wall portions 19 connecting the four sides of the heating unit 17 respectively. Note that the shape and size of the heating unit 17 are set to be substantially the same as the shape and size of the upper surface of the arithmetic processing device described later. In addition, the radiator 18
An injection nozzle 9 having a closed end is attached. The inside of the container 8 configured as described above is formed as a heat pipe.

The outer peripheral portion of the container 8 is covered with a cover 10 having a shape in which two flat plates having different sizes and thicknesses are stacked. The cover 10 is formed, for example, by solidifying a molten aluminum 15. That is, the heat pipe 7 is cast inside the cover 10. Also, on the lower surface of the cover 10,
Depression 2 shaped according to arithmetic processing unit 20 to be cooled
1 is formed. On the other hand, at the four corners of the cover 10, holes 24 through which bolts 23 for fixing the heat pipe 7 to, for example, the print board 22 are inserted are formed.
The sealing end of the injection nozzle 9 protrudes upward from the cover 10 in FIG.

Therefore, when the arithmetic processing unit 20 of the personal computer is cooled by the heat pipe 7, if the cover 10 is set so that the arithmetic processing unit 20 is fitted into the recess 21, the bolts are tightened. The heat pipe 7 is easily attached to the upper part of the arithmetic processing unit 20.

A plurality of flat fins 11 are provided on the upper surface of the cover 10 in an upright manner and arranged in parallel with each other. These fins 11 are made of the same Al or Al alloy as the cover 10 and are formed integrally with the cover 10. That is, the heat pipe 7 is wrapped by the cover 10 provided with the fins 11.

Next, a method of manufacturing the heat pipe 7 provided with the fins 11 having the above configuration will be described with reference to FIG. First, a container 8 to which an injection nozzle 9 is attached is prepared, and the container 8 and the fin 11 are integrated. That is, the container 8 is accommodated in the internal space of the lower mold 14 with the heating unit 9 facing downward in FIG. In this case, the opening end of the injection nozzle 9 is kept open to the atmosphere. The inner space of the lower mold 14 is a space having a shape substantially following the cover 10. Further, the lower die 14 is provided with a pressure plunger 16.

On the other hand, on the bottom surface of the upper mold 12, a plurality of flat rectangular recesses 13 are formed in a state of being arranged in parallel with each other. Therefore, a space (cavity) that substantially follows the shape of the cover 10 including the plurality of fins 11 by the internal space of the lower mold 14 and the internal space of the upper mold 12.
Are formed.

From the above state, the pressurizing plunger 16 is moved in the direction of the arrow in FIG. In this case, the entire outer peripheral portion of the container 8 and the intermediate portion of the injection nozzle 9 are covered with the molten metal, and the lower edge of each fin 11 is immersed in the molten metal 15. Then, the molten metal 15 is solidified by being left for a predetermined time in this state. As a result, the container 8 is cast in the cover 10 made of Al or an Al alloy in which the plurality of fins 11 are integrally formed. At the time when the above-mentioned die casting is performed, since the container 8 is not sealed, the internal pressure of the container 8 does not increase due to the heat of the molten metal 15 and the deformation and breakage thereof do not occur.

Next, the inside of the container 8 to which the fins 11 are attached is made into a heat pipe. Further, the cover 10
Holes 15 are formed at the four corners by a drill or the like. After that, cleaning, inspection, etc. are performed according to the usual manner. By the above procedure, the heat pipe 7 in which the fin 11 and the container 8 are firmly connected can be obtained.

As described above, according to the above specific example, the container 8 is cast in the cover by Al die casting, and the fins 11 formed integrally with the cover 10 are formed. The pipe 7 can be easily manufactured.

In each of the above embodiments, die casting is used as the means for casting the container. However, the present invention is not limited to the above embodiments. For example, a vacuum casting method, a low pressure casting method, Etc. can also be adopted. Further, the container and the fin may have shapes other than those exemplified in the above specific examples. For example, a container having a general circular cross section and a fin having a ring shape or a column shape may be used. Further, the materials of the container and the fins (covers) are not limited to the specific examples described above, and may be any materials suitable for the heat pipe.

[0034]

As is apparent from the above description, according to the first aspect of the invention, at least a part of the heat pipe container is cast-in by the cover, and the heat pipe container is in an upright state with respect to the container. Since the plurality of fin portions are integrally formed, the heat resistance between the fin and the container can be reduced as compared with the conventional heat pipe, and the connection strength between them can be improved.

According to the second aspect of the present invention, at least a part of the container is held inside a cavity having a plurality of concave portions following the shape of the fin, and then molten metal is injected into the cavity. After solidifying to cast the container and forming a plurality of fins upright from the container at the same time, it is made into a heat pipe, so the heat resistance between the fins and the container is small and the connection strength between them is high. Pipes can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a heat pipe according to a specific example of the present invention.

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

FIG. 3 is a schematic diagram showing a state where a container is housed inside a cavity.

FIG. 4 is a schematic diagram showing a heat pipe container according to another specific example.

FIG. 5 is a schematic diagram showing a state where the heat pipe is used for cooling an arithmetic processing unit.

FIG. 6 is a schematic diagram showing a state where a container is housed inside a cavity.

FIG. 7 is a schematic view showing an example of a conventional technique.

[Explanation of symbols]

7 ... heat pipe, 8 ... container, 10 ... cover,
11 fins, 12 upper molds, 13 recesses, 14
... lower mold, 15 ... molten metal.

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Yuji Saito 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd.

Claims (2)

[Claims] At least a part of a container of a heat pipe is cast-in by a cover made of a metal, and a plurality of fin portions standing upright with respect to the container are formed integrally with the cover. A heat pipe provided with fins. 2. A container for a heat pipe, at least a part of which is held inside a cavity having a plurality of concave portions following the shape of a fin, and then molten metal is injected into the cavity and solidified to form a container. A method of manufacturing a heat pipe having fins, wherein a plurality of fins are formed upright from a container at the same time as casting, and then the inside of the container is evacuated to form a heat pipe.