JP3908349B2 - Heat pipe with fins and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pipe that transports heat as the latent heat of vaporization of a working fluid, and more particularly to a heat pipe that integrates a container and fins and a method for manufacturing the same.
[0002]
[Prior art]
As is well known, a heat pipe is a container in which a condensable fluid such as water or alcohol is sealed as a working fluid inside a container (container) such as a sealed metal tube that has been vacuum degassed. When the working fluid evaporated at a high temperature flows to the low temperature part to dissipate heat and condense, heat is transported as latent heat of the working fluid.
[0003]
By the way, as is well known, fins are attached to the heat pipe container to increase the heat-dissipating area or the heat-absorbing area, thereby improving the heat exchange capability. Conventionally, various means for attaching the fin to the container have been proposed. One example will be described with reference to FIG.
[0004]
The heat pipe 1 shown in FIG. 5 is made of copper in which the container 2 forms a flat plate shape, and the fins 3 attached to the upper surface portion of the container 2 are a plurality of flat fins that are parallel to each other. The main body 4 is configured to stand vertically from the upper surface of the flat base 5 and is manufactured, for example, by an extrusion molding method using aluminum as a material. The fin 3 is 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.
[0005]
[Problems to be solved by the invention]
However, in the above heat pipe 1, since an adhesive or bonding agent having a lower thermal conductivity than Al or Cu is interposed between the container 2 and the fin 3, the heat between the container 2 and the fin 3. There was a disadvantage that resistance was large.
[0006]
Moreover, in the heat pipe 1 having the above-described configuration, the adhesive and the bonding agent are required to have good adhesion to both the container 2 and the fin 3. However, since the epoxy adhesive and the solder are difficult to adhere to either Al or Cu, conventionally, it has been difficult to connect the fin 3 to the container 2.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat pipe having a small thermal resistance between the fin and the container, and a manufacturing method capable of easily manufacturing the heat pipe. Is.
[0008]
[Means for Solving the Problem and Action]
In order to achieve the above object, according to a first aspect of the present invention, at least a part of a heat pipe container and one end of a plurality of fins are integrally cast by a metal cover, and the fins Are connected in a standing state with respect to the container.
[0009]
Therefore, in the invention of claim 1, since the fin is connected to the container by casting with a metal cover, the heat pipe having a high mounting strength and a low thermal resistance between the fin and the container is provided. Is done.
[0010]
In the invention described in claim 2, at least a part of the heat pipe container and one end of the plurality of fins are placed inside the cavity so that the fins stand up with respect to the container. And then injecting the molten metal into the cavity and solidifying the molten metal so that one end of the fin and the container are integrally cast and connected, and then the inside of the container is vacuum degassed to heat pipe It is characterized by becoming.
[0011]
Therefore, according to the manufacturing method of claim 2, since the container and the fin are connected by the metal formed by the solidification of the molten metal, the thermal resistance between the two is small, and between the container and the fin, Mounting strength is high. In addition, since the container is not sealed at the time of connecting the fin and the container, the internal pressure of the container does not increase due to the heat of the molten metal, and the deformation or breakage does not occur.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
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 example shown here is a heat pipe configured for cooling an arithmetic processing unit of a computer. The container 8 of the heat pipe 7 has a hollow, low-profile, substantially quadrangular pyramid shape.
[0013]
More specifically, the container 8 includes a square heating unit 9, a square that is about four times larger than the square heating unit 9, and a heat dissipating unit 10 that is opposed in parallel above the heating unit 9, and four heat dissipating units 10. It is a closed container made of copper formed by the inclined side wall portions 11 connecting the sides and the four sides of the heating unit 9 corresponding to each side. Note that the shape and size of the heating unit 9 are substantially the same as the shape and size of the upper surface of an arithmetic processing unit described later. The container 8 is filled with pure water (not shown) as a working fluid in a vacuum deaerated state to form a heat pipe.
[0014]
On the other hand, an injection nozzle 12 communicating with the inside of the container 8 is attached. As the injection nozzle 12, a small-diameter pipe having a circular cross section made of the same material as that of the container 8 is adopted, and an end portion protruding from the container 8 is crushed in a radial direction and sealed.
[0015]
The outer peripheral portion of the container 8 is covered with a cover 13 having a shape in which two flat plates having different sizes and thicknesses are overlapped. For example, the cover 13 is obtained by solidifying a molten Al or Al alloy. That is, the heat pipe 7 is cast inside the cover 13. Further, a concave portion 14 having a shape following an arithmetic processing device (not shown) to be cooled is formed on the lower surface portion of the cover 13. On the other hand, at the four corners of the cover 13, holes 15 are formed through which bolts for fixing the heat pipe 7 to, for example, a printed board are inserted. Note that the sealing end of the injection nozzle 12 projects from the cover 13 upward in FIG.
[0016]
Therefore, when cooling the processing unit of the personal computer with the heat pipe 7, if each bolt is tightened with the cover 13 installed so that the processing unit is fitted in the recess 14, the upper portion of the processing unit The heat pipe 7 can be easily attached to.
[0017]
A plurality of fins 16 made of aluminum flat plates are erected on the upper surface portion of the cover 13 and are attached in a state of being arranged in parallel to each other. The lower edges of these fins 16 in FIG. 1 pass through the top surface of the cover 13 and are in contact with the top surface of the heating unit 10 in the container 8. That is, the plurality of fins 16 are connected to the container 8 by being cast in the cover 13.
[0018]
Next, a method for manufacturing the heat pipe having the above configuration will be described with reference to FIG. First, a container to which the injection nozzle 12 is attached is prepared, and the container 8 and the fin 16 are integrated. That is, the container 8 is accommodated in the internal space of the lower mold (fixed mold) 17 with the heating unit 9 facing downward in FIG.
[0019]
On the other hand, with the plurality of fins 16 arranged in parallel with each other, the upper edge portion and the intermediate portion of the fins 16 are held by the placement core 18. Then, the placement core 18 is attached to the internal space of the upper mold (movable mold) 19 by appropriate means. In that case, the lower edge portion of each fin 16 protrudes from the bottom surface of the placement core 18 into the internal space of the upper mold 19 and the lower edge portion is in contact with the upper surface portion of the heat radiating portion 10 of the container 8. The child 18 is arranged.
[0020]
Accordingly, a space (cavity) having a shape substantially following the cover 13 is formed by the lower mold 17 and the placement core 18. Further, the lower mold 17 is provided with a pressurizing plunger 21 configured to press an Al or Al alloy molten metal 20 which is a material of the cover 13 from the right side to the left side in FIG.
[0021]
From the above state, the pressure plunger 21 is moved in the direction of the arrow shown in FIG. 4 to apply pressure to the molten metal 20. In that case, the entire outer peripheral portion of the container 8 and the intermediate portion of the injection nozzle 12 are covered with the molten metal. Further, the lower edge portion of each fin 16 is immersed in the molten metal 20. Then, the molten metal 20 is solidified by being left in this state for a predetermined time. As a result, the lower edges of the container 8 and the fins 16 are integrally cast in the cover 13 made of Al or Al alloy, and the three are connected to each other.
[0022]
In addition, since the container 8 is not sealed at the time of performing said die-casting, the internal pressure of the container 8 does not rise with the heat of the molten metal 20, and the deformation | transformation and damage do not arise.
[0023]
Next, the container 8 to which the fins 16 are attached is formed into a heat pipe. First, pure water (not shown) as a working fluid is injected into the inside of the container 8 through the injection nozzle 12 slightly more than a specified amount. This is because noncondensable gas is expelled from the container 8 next. As an example of this heat removal process, the container 8 is placed in a heating furnace or an oil bath (both not shown) with the injection nozzle 12 facing upward, and heated at about 120 ° C.
[0024]
Then, the non-condensable gas dissolved in the working fluid is discharged to the outside of the container 8 from the opening end of the injection nozzle 12 together with the vapor of the working fluid. That is, an amount obtained by subtracting the amount expelled as vapor from the total amount of working fluid previously injected into the container 8 is the substantial amount of the working fluid enclosed.
[0025]
Then, after expelling a predetermined amount of vapor, the tip of the injection nozzle 12 is crushed and sealed. As a result, the heat pipe 7 in which the container 8 itself is sufficiently evacuated is obtained. It should be noted that, in the heat eviction process, it is also possible to increase the internal pressure of the container 8 with the injection nozzle 12 temporarily tightened in advance and then open the temporary tightening portion to flush the working fluid. Further, holes 15 are formed in the four corners of the cover 13 by a drill or the like. After that, processes such as cleaning and inspection that follow the usual practice are performed. By the above procedure, the heat pipe 7 in which the fin 16 and the container 8 are firmly connected can be obtained.
[0026]
As described above, according to the above specific example, the fin 16 and the container 8 are integrally connected by the cover 13 formed by solidifying the molten metal 20 of Al or Al alloy. It is possible to easily manufacture the heat pipe 7 whose heat resistance is lower than that of the prior art.
[0027]
In the above specific example, a quadrangular frustum-shaped container and a flat fin are illustrated, but the present invention is not limited to the above specific example. For example, a container having a general circular cross section, a fin As a target, a ring shape or a cylindrical shape can be used.
[0028]
Further, in the above specific example, the entire outer peripheral portion of the heat pipe is covered with a cover having a recess, but the cover may be formed by simply connecting the fin and the container by casting. The range to cover may not be the whole area. In addition, what is necessary is just to provide a recessed part as needed. Furthermore, the material of the cover is not limited to Al or Al alloy, and a metal having excellent thermal conductivity such as Cu or Cu alloy can be used.
[0029]
【The invention's effect】
As is apparent from the above description, according to the invention of claim 1, at least a part of the heat pipe container and one end of the plurality of fins are integrally cast with the cover, and the fins are in contact with the container. Since it connects in the standing state, the thermal resistance between a fin and a container can be reduced rather than the conventional heat pipe, and those connection strengths can be improved.
[0030]
According to the invention of claim 2, at least a part of the container and one end of the plurality of fins are held inside the cavity so that the fins stand up with respect to the container. After injecting and solidifying the molten metal, one end of the fin and the container are integrally cast and connected, and then the inside of the container is made into a heat pipe, so the thermal resistance between the fin and the container is small In addition, it is possible to easily manufacture a heat pipe having high connection strength between them.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a heat pipe container according to an embodiment of the present invention.
FIG. 2 is a schematic view showing a side surface of a cover in which a heat pipe is cast.
FIG. 3 is a schematic view showing an upper surface of the cover.
FIG. 4 is a schematic view showing a state in which a container and fins are accommodated in a cavity.
FIG. 5 is a schematic diagram showing an example of the prior art.
[Explanation of symbols]
7 ... Heat pipe, 8 ... Container, 13 ... Cover, 16 ... Fin, 17 ... Lower mold, 18 ... Stationary core, 19 ... Upper mold, 20 ... Molten metal.

Claims (2)

At least a part of the container of the heat pipe and one end of the plurality of fins are integrally cast by a cover made of metal, and the fins are connected in a standing state with respect to the container. A heat pipe with fins. At least a part of the heat pipe container and one end of the plurality of fins are held inside the cavity so that the fins stand up with respect to the container, and then molten metal is injected into the cavity. In addition, the one end of the fin and the container are integrally cast and connected by solidifying the molten metal, and then the inside of the container is vacuum degassed to form a heat pipe. Heat pipe manufacturing method.

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