JP4827042B2 - Heat pipe manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a manufacturing method of Hitopai flop using a large number of metallic fibers as wick.
[0002]
[Prior art]
Conventionally, heat pipes that transport heat are widely known as latent heat of working fluids. This type of heat pipe evacuates from the inside of a sealed container, and then encloses a condensable fluid such as water, evaporates the working fluid by heat input from the outside, and condenses the vapor at a low temperature and low pressure. after flowing in, by condensing and radiating a heat conducting element that is configured to transport heat as latent heat of the working flow body. Therefore, in order to transport heat as the latent heat of the working fluid, the heat pipe has a transport capability of several tens to several hundreds of times the amount of heat transport by copper, which is said to have the highest thermal conductivity.
[0003]
In this type of heat pipe, the evaporated working fluid flows into the condensing part on the low temperature / low pressure side, and heat is transported. After transporting the heat, the condensed working fluid is transferred to the evaporating part (heat input part). In general, the action for the reflux is performed by utilizing the capillary pressure generated by the wick. Since this wick basically has the main function of generating capillary pressure, the effective capillary radius is preferably as small as possible, and the material constituting the wick is It is desirable that the wettability with the working fluid is excellent.
[0004]
The most common structure of the wick in the heat pipe is a narrow groove formed on the inner surface of the pipe, and is formed along the axial direction on the inner surface of the pipe by etching or cutting. In this type of groove type wick, a meniscus is generated on the opening end side of each narrow groove, so that the effective capillary radius can be reduced and a capillary pressure for refluxing can be generated in the working fluid. In addition, fine grooves to form a flow path for the liquid-phase working stream body. Therefore, it is possible to produce a pumping action for refluxing the liquid phase working fluid in a state where the flow path resistance when the liquid phase working fluid is refluxed is reduced.
[0005]
However, in a groove type wick, the groove width of the groove cannot be reduced below a predetermined limit due to processing technology restrictions, and there is a limit in improving the capillary pressure. Thus, a heat pipe is known in which a wick that replaces the narrow groove is formed by bundling extra fine wires such as carbon fiber and glass fiber and arranging the extra fine wire bundle along the inner surface of the pipe. In a heat pipe using this kind of extra fine wire wick (fiber wick), the effective capillary radius can be further reduced to further enhance the capillary action.
[0006]
[Problems to be solved by the invention]
In conventional heat pipes using extra fine wires, it is necessary to arrange the extra fine wires in close contact with the inner surface of the pipe. Therefore, a spiral leaf spring is arranged on the center side, and the extra fine wire is formed by the spiral leaf spring. Is pressed against the inner surface of the heat pipe container. However, the heat pipe is not always used in a straight line state, and in a small heat pipe called a micro heat pipe, the inner diameter is extremely small, so that the fine wire wick is aligned with the inner surface of the pipe. It was difficult to adhere.
[0007]
Therefore, in a heat pipe using a conventional fiber wick, the fiber is separated from the inner surface of the pipe, and heat transfer between the two is hindered. As a result, the heat resistance in the heat input part (evaporating part) to the heat pipe or the heat transfer characteristic from the heat pipe to the outside in the condensing part (heat radiating part) is impaired, resulting in the disadvantage that the heat transport capacity is hindered. It was.
[0008]
In addition, a slight gap formed between the fine wires becomes a reflux path for the liquid-phase working fluid, but the fine wire wick or fiber is messed up from the originally aligned bundling state due to bending of the heat pipe, etc. If the form is changed to a tightly bound state or an arrayed state, the thin space between the fibers serving as the reflux path for the liquid phase working fluid becomes obstructed or bends in a complicated manner. As a result, the flow resistance of the liquid phase working fluid is increased, and as a result, the reflux of the liquid phase working fluid to the evaporation part is hindered and the heat transport capability is likely to be lowered.
[0009]
The present invention was made in view of the above circumstances, it is an object to provide a method for producing a Hitopai flop having excellent thermal transport capability using metal fibers as wick.
[0010]
[Means for Solving the Problem and Action]
In order to achieve the above object, the present invention provides a heat pipe manufacturing method in which a metal fiber wick is provided along the inner surface of the heat pipe container. Te, with inserting a large number of metal fibers, in the center of the heat pipe container for its outer diameter than the inner diameter of the metal fibers inserted cylindrical portion is larger, the distal end side is formed in a tapered shape The cylindrical plug is inserted and the plug is moved relative to the heat pipe container and the metal fiber in the axial direction while pressing the metal fiber against the inner surface of the heat pipe container. The metal fiber is heated from the outer peripheral side where the metal fiber is pressed against the inner surface of the heat pipe container. It is a manufacturing method of the heat pipe, characterized by continuously sintering the bar on the inner surface of the heat pipe container.
[0019]
Thus, in the invention of claim 1, wherein the inner surface of the heat pipe container, the outer diameter than the inner diameter of the metal fibers inserted cylindrical portion is greatly formed, the tip side of the cylindrical shape formed in a tapered shape flop While pressing the metal fiber against the inner surface of the heat pipe by inserting the lug, the plug is relatively moved while being heated from the outside of the pressed part, and sintering of the metal fiber and the heat pipe container and between the metal fibers Sintering occurs. As a result, the sintered portion can be moved continuously, so that the heat pipe can be continuously processed and produced, and a long heat pipe can be efficiently processed and produced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described with reference to the drawings. Figure 1 shows a specific example of a heat pipe, which may be the inventions of the subject. The container 2 of the heat pipe 1 shown here is one in which both ends of a copper pipe material are sealed to form a hollow sealed state. Inside the container 2, a large number of copper ultrafine wires (fibers) 4 and a spiral pressing fitting 3 that presses the ultrafine wires 4 against the inner surface of the container 2 are inserted. Is contacted. A part of the multiple ultrafine wires 4 is sintered and maintained in a bundled state. Further, the portion of the ultrafine wire 4 that is in contact with the inner surface of the container 2 is sintered and fixed to the container 2. This extra fine wire 4 constitutes the wick of the heat pipe 1. In addition, a predetermined amount of a condensable fluid such as pure water or alcohol is sealed in the container 2 as a working fluid 7 in a vacuum deaerated state. One end of the heat pipe 1 configured in this way is a heating unit 5, and the other end is a heat radiating unit 6. A heating element or the like is in contact with the heating unit 5.
[0021]
FIG. 2 is a cross-sectional view of a part of the heat pipe 1 and a cross-sectional view showing a part of the heat pipe 1 in an enlarged manner. The sintering in a non-oxidizing atmosphere such as nitrogen gas atmosphere, is carried out by heating heating an inner surface and fine wire 4 of the container 2 at about 1000 ° C.. That is, as shown in the figure, the ultrafine wires 4 that were simply in contact before sintering, and the ultrafine wires 4 that are in contact with the inner surface of the container 2 are fused together and integrated.
[0022]
Also in the heat pipe 1 configured as described above, heat is transmitted from a heating element (not shown) or the like to the end portion which is the heating unit 5. The working fluid sealed in the container 2 is heated and evaporated by the heat transferred to the heating unit 5. In that case, the fine wires 4 functioning as wicks are sintered and integrated on the inner surface of the container 2, and a part of the fine wires 4 are sintered and integrated with each other. Heat is transferred between the integrated container 2 and the fine wire 4 by heat conduction. The heat of the working fluid 7 in contact therewith is transmitted from the inner surface of the container 2 and the surface of the ultrafine wire 4. Therefore, not only the inner surface of the container 2 but also the surface of the fine wire 4 integral therewith is substantially a heat transfer surface from the container 2 to the working fluid 7. In this way, since the heat transfer surface from the container 2 to the working fluid 7 is enlarged, the resistance (heat resistance) when heat is transferred from the container 2 to the working fluid 7 is reduced, and as a result, the heat pipe 1 Its own thermal resistance is reduced.
[0023]
In the heating unit 5, the working fluid 7 evaporates due to heat input from the outside, and the internal pressure increases. On the other hand, the temperature at the other end which is the heat radiating portion 6 is low due to heat radiation, and thus the internal pressure is low, so that the vapor of the working fluid 7 flows toward the heat radiating portion 6 due to the pressure difference. To do. The vapor of the working fluid 7 is deprived of heat in the heat radiating section 6, that is, radiates and condenses.
[0024]
In this way, the working fluid 7 liquefied in the heat radiating section 6 of the heat pipe 1 flows back to the heating section 5 side through the gap 8 formed between the plurality of fine wires 4. That is, in the heating unit 5, when the working fluid 7 is evaporated, a capillary pressure is generated by the meniscus between the fine wires 4, and the capillary pressure causes the liquid-phase working fluid to flow toward the heating unit 5. It is done. By repeatedly evaporating, condensing and refluxing the working fluid 7 as described above, the heat of the heating element is transported and the heating element is cooled.
[0025]
Therefore, in the heat pipe 1 shown as the specific example, the ultrafine wire 4 functions as a wick, and the liquid-phase working fluid 7 is returned from the heat radiating unit 6 to the heating unit 5 by the capillary pressure generated on the heating unit 5 side. Can be made. Further, since the fine wire 4 is integrated with the container 2 so as to be integrated, it is specifically sintered, so that the fine wire 4 substantially becomes a part of the container 2 and becomes a working fluid 7. In addition, heat is transmitted from the working fluid vapor to the container 2 in the heat radiating unit 6. That is, the substantial heat exchange area between the container 2 and the working fluid 7 is widened, and the thermal resistance as the heat pipe 1 is reduced. Furthermore, since the fine wires 4 are sintered and bound together, and are sintered and fixed to the inner surface of the container 2, the gap 8 formed between the fine wires 4 functions as a reflux path. As a result, the flow resistance of the working fluid 7 is reduced, and as a result, the reflux performance is improved.
[0026]
Furthermore, since the gaps formed between a plurality of the fine wires 4 that are bundled together and bound by sintering serve as a reflux path for the liquid-phase working fluid, many of the reflux paths for the liquid-phase working fluid. However, it will be in the state shielded from the gaseous-phase operation | movement flow path formed in the inner peripheral side of the bundled extra fine wire. For this reason, the degree of direct exposure of the liquid phase working fluid in the middle of reflux to the working fluid vapor flowing at high speed is reduced, and also in this respect, the reflux performance of the liquid phase working fluid is improved. Therefore, coupled with the low thermal resistance of the heat pipe 1, a large amount of heat can be transported without causing dryout in the heating unit 5, and the heat transport capacity of the entire heat pipe is improved.
[0027]
The results obtained by our experiments are shown in FIG. Figure 3 is characteristic of the conventional general heat pipe with grooves wick, a conventional heat pipe simply inserted into the heat pipe container fiber wick, the heat pipe can be this inventions the subject It is a diagram which shows the result of having measured. ● marks in FIG. 3 represents the heat pipe of the measurement results of the groove wick type, also ■ mark indicates the measurement results of the conventional heat pipes using fiber wick, ▲ mark, and the inventions of the subject The measurement result of the heat pipe which can be shown is shown.
[0028]
As apparent from FIG. 3, the groove wick type heat pipe despite the heat input does not particularly increase, the thermal resistance has become sharply increases, which Doraiau bets in the heating section in heat input arising This indicates that no further heat transport can be performed. On the other hand, in the fiber wick type heat pipe, the heat input can be increased without particularly increasing the thermal resistance, and the heat transport amount can be increased as compared with the groove wick type heat pipe. it can. Further, in the heat pipe wick by sintering metallic fibers are used, the thermal resistance despite the increase in heat input almost constant value, moreover than conventional heat pipe fiber wick type It has become clear that the heat resistance is small, and therefore the heat transport capability is much better than the conventional heat pipe.
[0029]
Next, an embodiment of the method of heat Topaipu described above. FIG. 4 shows the manufacturing process of one specific example of the manufacturing method of the present invention. 4 that are the same as those shown in FIG. 1 or 2 are given the same reference numerals, and detailed descriptions thereof are omitted.
[0030]
First, as a material of the container 2 of the heat pipe 1, a copper pipe material 21 having a circular cross section shown in FIG. 4 is prepared, and the pipe material 21 is degreased and cleaned. As the cleaning method, for example, a conventionally known method such as cleaning using an appropriate solvent or ultrasonic cleaning is used. On the other hand, a large number of copper fine wires are prepared as the fine wires 4 to be wicks. Then, the ultrafine wire 4 is degreased and washed.
[0031]
A large number of ultrafine wires 4 that have been cleaned are inserted into the pipe material 21 that has been cleaned along the inner surface thereof in a ring-like manner. Or at the same time, the pressing metal fitting 31 is inserted into the inner peripheral side of the fine wire 4 arranged in an annular shape. The pressing metal 31 is used to press the ultrafine wire 4 against the inner peripheral surface of the pipe member 21. As an example, an elastic spiral metal band is used. Such a metal strip is pulled in the axial direction to reduce the outer diameter, and is inserted into the center portion of the pipe material 21 in that state. Thereafter, the tensile force is released to increase the outer diameter by elasticity, and the elasticity is increased. The extra fine wire 4 is pressed against the inner peripheral surface of the pipe material 21 by force. This state is shown in FIG.
[0032]
Thereafter, as shown in FIG. 4, the pipe material 21 into which the fine wire 4 and the pressing metal fitting 31 are inserted is housed in the heating furnace 9, and the internal temperature is gradually increased. And the internal temperature of the heating furnace 9 is hold | maintained at about 1000 degreeC in non-oxidizing atmosphere, and the ultrafine wire 4 and the pipe material 21 are sintered and fixed.
[0033]
And the opening end of the pipe material 21 is sealed, the pipe material 21 is sealed, and the container 2 is formed. At that time, as shown in FIG. 4, one end of the injection nozzle 10 is inserted into the opening and fixed by means such as welding or brazing. As the injection nozzle 10, a small diameter pipe made of copper and having a circular cross section is employed.
[0034]
Next, the container 2 to which the injection nozzle 10 is fixed is degreased and washed. Thereafter, the container 2 is made into a heat pipe. That is, the working fluid is injected into the container 2 through the injection nozzle 10 slightly more than the specified amount. This is because noncondensable gas is expelled from the inside of the container 2 in the next step. As an example of this heating-out process, here, as shown in FIG. 4, the container 2 is installed in a silicon oil bath or the like so that the end provided with the injection nozzle 10 is upward, and heated to about 120 ° C. Then, the non-condensable gas dissolved in the working fluid is discharged from the opening end of the injection nozzle 10 to the outside of the container 2 together with the vapor of the working fluid. That is, an amount obtained by subtracting the amount expelled as steam from the total amount of the working fluid previously enclosed in the container 2 is a substantial amount of the working fluid.
[0035]
Then, after expelling a predetermined amount of vapor, temporary sealing is performed by caulking the tip side of the injection nozzle 10 or the like. Therefore, this container 2 becomes the container 2 of the heat pipe 1 that is sufficiently deaerated. In this heating-out process, it is also possible to increase the pressure inside the container 2 with the injection nozzle 10 temporarily tightened in advance, and then open the temporary tightening portion to flush the working fluid. In this embodiment, the heating and expelling method is illustrated as a method for degassing and enclosing the working fluid into the container 2, but a vacuum pump method, a gas liquefaction method, or the like may be employed instead.
[0036]
In the above example, the container 2 and the ultrafine wire 4 are made of copper, but this material is not limited to copper, and copper oxide or copper dioxide may be used to improve wettability.
[0037]
In addition, in order to improve the wettability, the inner surface of the container 2 is roughened in a range inside the container 2 such as sand blasting using a blasting device (not shown), etching or grinding using sandpaper. It is also possible to employ a process for forming a pre-sintering process.
[0038]
Moreover, although the pressing metal fitting 31 is a spiral metal band, this is not limited to the above, and it may be a round wire spring. In short, any material that presses the ultrafine wire 4 against the inner surface of the pipe member 21 by elastic force may be used.
[0039]
Next , a heat pipe manufacturing method that enables continuous processing according to the present invention will be described with reference to FIG. FIG. 5 shows a specific example of the manufacturing method of the present invention. 5 that are the same as those shown in FIGS. 1, 2, and 5 are assigned the same reference numerals, and detailed descriptions thereof are omitted.
[0040]
The example shown in FIG. 5 is an example in which the plug 11 is used as a member for pressing the ultrafine wire 4 against the inner peripheral surface of the pipe material 21. That is, the plug 11 is a member whose maximum outer diameter is slightly larger than the inner diameter of the fine wire 4 arranged annularly along the inner peripheral surface of the pipe material 21, and the tip end side is a tapered member. It is attached to the tip.
[0041]
The plug 11 is inserted into the inside of the pipe member 21 in which the ultrafine wires 4 are arranged along the inner peripheral surface, and the plug 11 and the pipe member 21 so that the plug 11 advances in the pipe member 21. Are moved relatively in the axial direction. Since the maximum outer diameter of the plug 11 is set to be larger than the inner diameter of the fine wire 4 arranged in an annular shape, the extra wire 4 is pressed against the inner peripheral surface of the pipe material 21 by the relative advancement of the plug 11. .
[0042]
In this manner, with the plug 11 pressed against the inner peripheral surface of the pipe material 21 by the plug 11, the pipe material 21 is heated and heated by the heating coil 13 disposed on the outer peripheral side of the pressed portion. In that case, when the pipe material 21 and the ultrafine wire 4 are made of copper, the heating temperature is about 1000 ° C. The atmosphere is a non-oxidizing atmosphere such as nitrogen gas in order to prevent oxidation of the pipe material 21 and the ultrafine wire 4.
[0043]
As a result, since the ultrafine wire 4 is heated while being pressed against the inner surface of the pipe material 21, sintering occurs between the two, and the ultrafine wire 4 in contact with the inner surface of the pipe material 21 becomes the pipe material 21. And integrated with the inner surface (ie, the inner surface of the heat pipe container). At the same time, sintering occurs in at least a part of the ultrafine wires 4 and the ultrafine wires 4 are fixed in the annular bundling state. In this case, a gap along the axial direction remains between the fine wire 4 and the inner surface of the pipe material 21 and between the fine wires 4 as shown in FIGS. Becomes the flow path of the liquid phase working fluid.
[0044]
Therefore, according to the method using such a plug, since the ultrafine wire 4 and the pipe material 21 can be continuously run while these can be sintered, continuous processing or long processing can be performed. It becomes possible. Further, the pressing need for fittings etc. are eliminated give press the hairline 4 on the inner surface of the pipe 21. As a result, the step of inserting the fixing bracket into the pipe member 21 and the step of pulling out after sintering are eliminated, and the production efficiency can be further increased.
[0045]
In addition, this invention is not limited to said specific example. Therefore, in the present invention, as the metal fiber, an appropriate metal fiber can be used in addition to the above-described copper fine wire. The wire diameter is about 50 to 100 μm in the case of copper fiber. Similarly, the heat pipe container is not limited to copper, and an appropriate metal pipe is used. The inner diameter is about several mm as an example. Further, in the present invention, the method of fusing and integrating the metal fibers with the inner surface of the heat pipe container is a method by an appropriate welding such as ultrasonic welding or friction welding in addition to sintering, or a method by joining such as brazing. Also good. Furthermore, in order to improve the wettability between the metal fiber or the container and the working fluid, an oxide film may be formed on the inner surface of the metal fiber or the container, or the surface may be roughened by sandblasting or etching. Good.
[0046]
【The invention's effect】
As described above, according to the manufacturing method of claim 1, the outer diameter is formed larger than the inner diameter of the cylindrical portion in which the metal fiber is inserted on the inner surface of the heat pipe container, and the tip end side is formed in a tapered shape. The cylindrical fiber plug is inserted into the heat pipe while pressing the metal fiber against the inner surface of the heat pipe, and the plug is relatively moved while being heated from the outside of the pressed portion to sinter the metal fiber and the heat pipe container. Sintering of metal fibers occurs. As a result, since the sintered portion can be moved continuously, the heat pipe can be continuously processed and produced, and a long heat pipe can be efficiently processed and produced. Therefore, it becomes unnecessary metal such as pressing the metal fibers to the inner surface of the heat pipe container, because the reduction of material costs and manufacturing processes, such as the fitting is made possible, as possible out that to reduce the production cost.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional side view showing a specific example of a heat pipe that can be an object of the present invention.
FIG. 2 is a partial cross-sectional view of FIG. 1 and a partial view enlarging a part thereof.
FIG. 3 shows the characteristics of a heat pipe that can be an object of the present invention, a conventional general heat pipe using a groove wick, and a conventional heat pipe in which a fiber wick is simply inserted into a heat pipe container. It is a diagram which shows the result of having measured.
It is a diagram showing a manufacturing process in an embodiment of Figure 4. The method of heat Topaipu shown in FIG.
5 is a diagram for explaining a tool body of the manufacturing method of the heat pipe according to the present invention.

Claims (1)

In the heat pipe manufacturing method in which a metal fiber wick is provided along the inner surface of the heat pipe container,
And placed along the inner surface of said heat pipe container, as well as inserting the large number of metal fibers, in the center of the heat pipe container for its outer diameter than the inner diameter of the metal fibers inserted cylindrical portion larger A cylindrical plug having a tapered tip is inserted, and the plug is pressed against the heat pipe container and the metal fiber in the axial direction while pressing the metal fiber against the inner surface of the heat pipe container. The metal fiber is heated from the outer peripheral side of the portion where the metal fiber is pressed against the inner surface of the heat pipe container by the plug, and the metal fiber is continuously sintered on the inner surface of the heat pipe container. A method for manufacturing a heat pipe.

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