JPS5833477B2 - Heat pipe manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat pipe, and particularly to a method for filling a heat pipe with a working fluid.

In the conventional method of filling a heat pipe with working fluid, as shown in FIG.
The degassed working fluid 3 is placed in the liquid reservoir 4, and the air inside the hollow heat pipe body 5 is evacuated to the desired degree of vacuum by opening the valve 6 and using the vacuum pump T. By closing the valve 6 and opening the valve 1, a predetermined amount of working fluid is filled into the heat pipe hollow tube 5, and then the nozzle 8, which is the opening of this hollow tube, is sealed and cut. .

In this method, the amount of hydraulic fluid to be filled into the heat pipe hollow tubular body 5, which has been set to the desired degree of vacuum, is measured by operating the valve 1, so it is quite difficult to accurately fill the predetermined amount. , and a degassing device 2 (e.g., a vacuum evacuation device using a vacuum evacuation method) for degassing the filled hydraulic fluid, which is disadvantageous in that it lacks economic efficiency.

In addition, compared to the above-mentioned method, as a method that allows more accurate filling of the amount of working fluid and does not require a special degassing device for the working fluid, before evacuating the inside of the hollow tube for the heat pipe, In order to prevent the working fluid from evaporating and decreasing by injecting the working fluid and drawing a vacuum, this method involves freezing the working fluid, drawing a vacuum, and sealing the hollow tubular body for the heat pipe. is proposed.

It is stated that the advantages of this method are that it is possible to fill an accurate amount of working fluid, and that it is possible to sufficiently create a vacuum for degassing the inside of this hollow tube.

This method does not require a hydraulic fluid degassing device compared to the above-mentioned method because it is possible to accurately fill the working fluid and to create a sufficient degassing vacuum inside the hollow tube for the heat pipe. Although this is a unique method, in order to manufacture high-performance heat pipes, this method freezes the working fluid before drawing a vacuum inside the hollow tube for the heat pipe. The air inside the hollow tube for the heat pipe is trapped, and the air in this frozen working fluid cannot be degassed in a short time no matter how high vacuum is created inside the hollow tube for the heat pipe. In order to completely degas the air in the frozen working fluid, it is necessary to maintain a high vacuum for a long time, which has the drawback of impractical use.

The present invention was made in view of the above-mentioned conventional problems.
A predetermined amount or slightly more than the predetermined amount of working fluid is injected into the hollow tube for the heat pipe in advance, and after solidifying the working fluid, the inside of the hollow tube for the heat pipe is evacuated. I feel like it.

After that, the connection between this hollow heat pipe body and the vacuum evacuation system is closed, and then the working fluid is melted by heating while maintaining this vacuum state, and the trace amount that was trapped when the working fluid solidified is By discharging a small amount of non-condensable gas, solidifying the working fluid from which this small amount of non-condensable gas has been removed again, and evacuating the inside of this hollow heat pipe tube, a small amount of non-condensable gas can be removed. A method for producing a heat pipe, which seals the open end of a hollow tube body for a heat pipe after repeating a series of deaeration cycles, that is, heating-gas discharge and coagulation-deaeration one or more times, and the above-mentioned working fluid. After coagulating and degassing in advance, the series of heating-gas discharge and coagulation-degassing cycles is repeated one or more times, and the connection between the hollow heat pipe body and the vacuum exhaust system is closed. , this heat pipe is heated to 50℃~1 from the maximum operating temperature.
After heating at a temperature higher than 00℃ for a predetermined period of time, the working fluid is solidified again, and after degassing the extremely small amount of non-condensable gas generated by this high-temperature heating, the open end of the hollow tube body for the heat pipe is This is a method for manufacturing a sealed heat pipe.

The present invention will be explained in detail below using one example.

The heat pipe used in the example has a wick made of fine metal wires made of pure copper that has a capillary action and is in close contact with the inner wall of a container made of pure copper with an outer diameter of 12.7 mm and an effective length of 250 mm, and a steam passage is provided in the wick. It has a structure in which one end of the tube is sealed, and the opening at the other end is equipped with a nozzle for injecting working fluid and evacuation.

Example 1 After injecting 5.25 cc of distilled water into the above-mentioned hollow tube for a heat pipe, and attaching the nozzle which is the opening of this hollow tube for a heat pipe to a vacuum exhaust system, -75 ℃
After cooling the distilled water and solidifying the distilled water, the inside of the hollow tube for the heat pipe was evacuated to 2 x 10-5 mrnHg.
The connection to the vacuum exhaust system was closed, and the distilled water was further heated to 60°C to melt it and a small amount of non-condensable gas trapped during solidification was discharged, and then cooled again to -75°C to remove the working fluid. After solidifying and evacuating the inside of this hollow tube to 2 x 10-50-5i, the nozzle was crushed and welded to seal it to form a heat pipe.

One end of this heat pipe, 50 mm long, was heated to 100°C and the temperature distribution was measured. As shown in I in Figure 2, the temperature drop at the tips C2D, E, F, and G with respect to the heated parts A and H is It was found that the trace amount of non-condensable gas was degassed very well at 2°C, and extremely good heat transfer characteristics were exhibited.

Example 2 As shown in Example 1, the heat pipe manufactured according to the present invention exhibits extremely good heat transfer characteristics and has no problems with thin tubes in practical use. After coagulating, degassing, and heating under the same conditions as in Example 1 using The nozzle was crushed and welded to form a heat pipe.

As in Example 1, one end of this heat pipe is 50 mm long.
The results of heating to 00°C and measuring the temperature distribution are as shown in H in FIG.

The temperature drop at the tips C, D, E, F, and G with respect to B was 1.0° C., which was even smaller than that in Example 1, demonstrating extremely excellent heat transfer characteristics.

Example 3 A heat pipe produced in the same manner as in Example 2 was prepared with the connection between the heat pipe and the vacuum non-gas system closed. Since this heat pipe uses distilled water as the working fluid, it was The temperature was 200'C, and after heating for 24 hours at 250°C, which is 50°C higher than the maximum operating temperature, the temperature distribution of the heat pipe was measured. The temperature drop to the heated part is 1.0℃.
However, the temperature was 1.5°C, indicating that a very small amount of non-condensable gas was generated.

After this high-temperature heating, the heat pipe was cooled again to -75° C. and degassed at 2×10 −5 ixiHg, and then the nozzle was crushed and welded to seal it to form a heat pipe.

The temperature distribution of this heat pipe was measured at 100°C in the same manner as above, and the results were the same as those in Figure 2, with a temperature difference of i,0°C between the heated part and the tip, showing extremely excellent heat transfer characteristics. .

The amount of decrease in hydraulic fluid in the above three examples is 0.005~
It was a value of about 0,000 oxcc, which did not pose a problem for a predetermined injection amount.

If this small amount of decrease seems to be a problem,
The above-mentioned amount may be injected in a larger amount as a correction amount for the predetermined injection amount.

As a reference example, a hollow tube body for a heat pipe equivalent to that in Example 1 was used, and 5.25C
After injecting distilled water of C, attach the nozzle, which is the opening of this hollow tube body for heat pipe, to the vacuum exhaust system, and -75
The tube was cooled at .degree. C. to freeze the distilled water, and the inside of the heat pipe hollow tube was evacuated to 2.times.10.sup.-5 mmHg for degassing.The nozzle was then crushed and welded to seal the tube to obtain a heat pipe.

The temperature distribution of this heat pipe was measured in the same manner as in Example 1. The results are shown in Figure 2 (■). It can be seen that gas remains and the heat transfer characteristics are poor.

As described above, according to the present invention, not only can the amount of working fluid be filled accurately, but also the non-condensable gas in the heat pipe can be completely degassed.

Moreover, there is no need for special equipment to degas the hydraulic fluid.
The present invention has the advantage that high-performance heat pipes can be easily obtained at low cost, such as that high-performance heat pipes can be manufactured easily.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional heat pipe manufacturing method. FIG. 2 is a diagram showing the temperature distribution characteristics of heat pipes manufactured by the method of the present invention and the conventional method. 1... Valve, 4... Liquid reservoir, 6... Valve, 2... Deaerator, 3... Working fluid, 5.
...Hollow tube body for heat pipe, 7...Vacuum pump, 8...Nozzle.

Claims (1)

[Scope of Claims] 1. A predetermined amount or slightly more than a predetermined amount of working fluid is injected into the hollow tube for a heat pipe in advance, and after solidifying this working fluid, the inside of the hollow tube for a heat pipe is evacuated. The heat pipe is degassed by pulling the heat pipe, and the connection between the hollow tube body for the heat pipe and the vacuum exhaust system is closed. Next, while maintaining this vacuum state, the working fluid is melted by heating, and the working fluid is removed. The minute amount of non-condensable gas trapped during solidification is discharged, and the working fluid from which this minute amount of non-condensable gas has been removed is solidified again, and the inside of the hollow tube for the heat pipe is evacuated. A method for manufacturing a heat pipe, which comprises repeating a series of cycles for degassing non-condensable gas one or more times, and then sealing the opening of the hollow tube body for the heat pipe. 2. Inject a predetermined amount or slightly more than the predetermined amount of working fluid into the heat pipe hollow tube in advance, solidify this working fluid, and then evacuate the heat pipe by drawing a vacuum inside the heat pipe hollow tube. Then, the connection between this hollow heat pipe body and the vacuum exhaust system is closed, and then the working fluid is melted by heating while maintaining this vacuum state, and the minute amount trapped when the working fluid solidifies is removed. The working fluid from which this trace amount of non-condensable gas has been removed is solidified again, and the inside of this hollow heat pipe tube is evacuated to remove the trace amount of non-condensable gas. After repeating a series of cycles one or more times, with the connection between the heat pipe and the vacuum exhaust system closed, the heat pipe is heated to a temperature 50°C to 100°C higher than the maximum operating temperature of the heat pipe for a predetermined period of time. After heating, the working fluid is solidified again,
A method for manufacturing a heat pipe, which comprises: sealing the opening of the hollow tube body for a heat pipe after degassing a very small amount of non-condensable gas generated by this high-temperature heating.