JPH02275294A - Heat pipe of electricity insulation type - Google Patents

Abstract

PURPOSE:To provide a heat pipe of electricity insulation type which excels in heat absorption and heat radiation by connecting a first metal pipe which has in its inner face many tilted straight grooves with a second metal pipe which has on its inner face many straight grooves which cross one another among them. CONSTITUTION:The shape of a straight groove provided in the inner face of a first metal pipe 1 which serves as a heat radiation section can be any of the V shape, square groove shape, and wave shape. The angle of inclination of the groove with respect to the direction of the axis of the pipe is alpha to one direction. The angle alphais preferably in the range of 2 - 10 deg.. the shape of a straight groove that is provided in the inner face of a second metal pipe which serves as a heat absorption section can be any of the V shape, square groove shape, and wave shape and the straight grooves run in the direction of the pipe axis and they cross one another among them. The angle of inclination of the grooves with respect to the axis is preferably in the range of 2 - 45 deg.. In between the first metal pipe and second metal pipe an electricity insulation cylinder 3 is provided and it is connected to both metal pipes on its ends. The cylinder 3 is made of alumina, magnesia, glass, ceramics, etc. and shuts off the electricity leakage from a semiconductor in order to keep the electric current from reaching the first metal pipe which is a heat radiation section.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in electrically insulated heat pipes used for cooling electrical and electronic equipment.

[Conventional technology and its issues]

Conventionally, heat pipes have been used for cooling semiconductors such as thyristors. For example, as shown in Fig. 7, this heat vibrator connects a first metal tube (1) and a second metal tube (2) made of copper, aluminum, stainless steel, etc. through an electrically insulating tube (3). They are joined together and filled with an electrically insulating working fluid such as Freon to form a heat vibrator.

As described later, this electrically insulated heat pipe is used for cooling semiconductors such as Cyrisk.The second metal tube is inserted and fixed into a metal block on which a semiconductor element is mounted, and the heat generated by the semiconductor element is transferred to the metal block. The heat generated by the semiconductor element is absorbed by the second metal tube, transferred to the first metal tube by the action of the heat vibrator, and naturally or forcedly cooled by the fins provided on the first metal tube. It radiates heat.

However, in the above-mentioned conventional electronically insulated heat pipe, the inner surface of both the first metal tube and the second metal tube is either a normal bare tube or a rectangular groove (4) as shown in the cross section in Figure 8. A metal tube with a special coating is used.

For this reason, the boiling (evaporation) and condensing effects of the working fluid on the inner surface of the heat vibrator are not sufficiently exerted, and there is a problem in that the thermal resistance is large and the performance is low, especially at low heat input.

(Problems to be Solved by the Invention) As a result of studies on the above-mentioned problems, the present invention has electrical insulation properties, sufficiently exhibits boiling and condensation effects, has low thermal resistance especially at low heat input, has endothermic properties, We have developed an electrically insulated heat pipe with excellent heat dissipation.

[Means and effects for solving the problem] The present invention includes a first metal tube having a large number of inclined grooves and one end of which is constricted into a conical or hemispherical shape, and a large number of intersecting grooves on the inner surface. The pipe is connected to a second metal pipe whose one end is conically or hemispherically constricted through an electrically insulating cylinder to form a communicating pipe, the inside of which is evacuated and a certain amount of electrically insulating liquid is injected and sealed. This is an electrically insulated heat pipe.

That is, the present invention has one end constricted into a conical or hemispherical shape as shown in FIG. A large number of grooves (M) having an angle (α) inclined to one side with respect to
The first metal tube (1) provided with this is used as a heat dissipation part, and one end is similarly constricted into a conical or hemispherical shape, and the inner surface has a large number of V-shaped or concave holes intersecting in the axial direction as shown in Fig. 3. A second metal tube (2) provided with grooves (N) in a shape of a letter or a wave shape is used as a heat absorbing part, and a sealing material made of iron-Nisokel alloy or the like is provided between the heat radiating part and the heat absorbing part. The heat pipe is connected by an electrically insulating tube (3) and filled with an electrically insulating liquid such as Freon as a working fluid.

The shape of the groove (M) provided on the inner surface of the first metal tube (]) which serves as the heat dissipation part may be V-shaped, concave or wave-shaped, and the shape of the groove (M) provided on the inner surface of the first metal tube (]) serving as the heat dissipation part may be V-shaped, concave-shaped, or wave-shaped. It has an angle (α) inclined in one direction, and this angle is 2 to 10
A range of 50° is preferred. These grooves expand the surface area of the inner surface of the heat pipe, promoting condensation characteristics, and improving the reflux of the working fluid to improve heat dissipation characteristics.

The shape of the grooves (N) provided on the inner surface of the second metal tube (2) serving as the heat absorbing portion may be V-shaped, concave, or wave-shaped, but they intersect in the axial direction as shown in Figure 3. This is to provide grooves. The angle is preferably 2 to 45' inclined in the axial direction. These grooves increase the inner surface area,
The boiling characteristics of the working fluid are promoted and the endothermic effect is improved, which is particularly effective at low heat input.

In addition, an electrically insulating tube (3) made of, for example, alumina, magnesia, glass, or ceramic is connected between the first metal tube and the second metal tube to block electrical leakage from the semiconductor and to prevent heat dissipation. Make sure that the current does not reach the first metal tube.

In addition, the connection between the electrical insulation cylinder and the metal pipe mentioned above is made of iron-nickel.
Better bonding can be achieved by connecting through a sealing material such as aluminum alloy.

Further, the metal tubes used for the first metal tube and the second metal tube may have the same diameter, but for example, the second metal tube serving as the heat absorbing portion may be used as the first metal tube serving as the heat radiating portion. The heat absorption effect can be improved by making the diameter larger. Furthermore, the cross-sectional shape is not limited to a circle, but may be an ellipse or other irregular shape. As the material of this metal tube, copper, aluminum, stainless steel, etc. can be used.

〔Example〕

An embodiment of the present invention will be described below.

■ The height of the mountain on the inner surface is 0.3 mm, and the pinch is 0.9 Km.
The groove shown in Fig. 2 has a shape of
The upper end of a copper pipe with an outer diameter of 22.23 aam is formed into a hemispherical shape by spinning, and the tip is further formed into a nozzle with a small hole by spinning to become a heat dissipation part as shown in Figure 1. This was referred to as a first metal tube (1). Next, the height of the mountain on the inner surface of a copper pipe of the same diameter is 0.311.
IIB, pitch 0.9 mi+, grooves (N) shown in Fig. 3 with a ■-shape and inclined at 5 degrees on both the left and right sides in the axial direction are provided, and the tips of these grooves are similarly formed into a hemispherical shape by spinning, and then welded. A second metal tube (2) that is sealed and becomes a heat absorption part
And so.

Fe made of 42Ni is placed between the first and second metal tubes.
-Incorporate an alumina electrically insulating tube (3) equipped with a Ni alloy sealing material (not shown), connect the sealing material, electrically insulating tube, and metal tube together using high-frequency heating, and then remove the inside. After cooling, a certain amount of Freon 113 was injected through the nozzle and sealed to form an electrically insulated heat pipe.

In the heat pipe manufactured in this way, a fin is attached to the first metal tube of the heat dissipation section, the second metal tube is attached to a metal block equipped with a semiconductor element such as Cyrisk, which becomes the heat absorption section, and the second metal tube becomes the heat absorption section. This is used in a cooler that has a structure in which two are connected with an electrically insulating cylinder. In this case, heat generated by a semiconductor such as SIRISK is transferred to the second metal tube of the heat absorption section through the metal block, and is radiated by the first metal tube of the heat radiation section. At this time, since an electrically insulating cylinder is provided, only heat is transferred to the upper heat dissipation part, which is electrically insulated and there is no risk of electric shock.Also, the hydraulic fluid should be made of electrically insulating material such as Freon. Safety is ensured.

The first metal tube of the heat dissipation section is provided with a V-shaped spiral groove on its inner surface, which increases the condensation heat transfer coefficient on the inner surface and improves heat dissipation. Since spiral grooves are provided that cross left and right, as the surface area increases, the boiling heat transfer coefficient increases and the heat absorption property improves.

The above heat pipe is held vertically as shown in Figure 4, and the lower part is used as a heat input part and the upper part is used as a heat radiation part, and human power is applied while cooling the pipe, and the thermal resistance R ('C/W) and the input p
We investigated the relationship between (w). Note that thermal resistance R = (T, -T,
)/P.

The results are shown in Fig. 5. As is clear from this figure, the heat pipe of the present invention generally has a lower thermal resistance than the conventional heat pipe (bare pipe), and heats up especially under low input P of 50 W or less. It was found that the resistance was significantly reduced. Therefore, it was confirmed that the heat pipe of the present invention exhibits excellent performance especially under low thermal power.

Next, an example of use of the insulated heat vibrator of the present invention will be described.

FIG. 6 shows an assembly of the insulated heat pipe of the present invention as a cooler for a semiconductor for Cyrisk power use. A large number of fins (5) are inserted into the first metal tube (1) to form a heat dissipation section, and the second metal tube is fitted with a silisk (6) and inserted and fixed into a metal block (7) to form a heat absorption section. becomes. A plurality of these coolers were assembled into a SIRISK cooling stack as IMi and used for an inverter.

As an application example of the present invention, in addition to the above, it is also possible to use this portion as a silisk cooler by cooling with water or oil without inserting fins.

In this case as well, since it is electrically insulated, it is easy to handle and the cooling performance is improved.

Furthermore, when the heat pipe of the present invention is used alone, the heat generated by the transformer can be removed by inserting the heat absorbing part into the winding part of the transformer and radiating heat by one of the heat radiating parts. As described above, the heat pipe of the present invention is suitable for cooling the heat generated by electrical and electronic equipment, and can be applied to a wide range of applications.

[Effects] As explained above, according to the present invention, it is possible to obtain an electrically insulated heat pipe having electrical insulation properties and excellent heat absorption and heat dissipation properties, which has a remarkable industrial effect. .

[Brief explanation of drawings]

FIG. 1 is a partially sectional view of an electrically insulated heat pipe according to an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of the section B-B' in FIG. 1, and FIG. 3 is the same as that shown in FIG. FIG. 4 is a schematic diagram explaining the test method for the electrically insulated heat pipe of the present invention, and FIG. 5 is a diagram showing the performance of the electrically insulated heat pipe of the present invention. 6 is a perspective view showing an example of using the electrically insulated heat pipe of the present invention, FIG. 7 is a partial cross-sectional view of a conventional electrically insulated heat pipe, and FIG. 8 is a diagram showing A of FIG. 7. - It is a cross-sectional view of the A' section. 1...First metal pipe, 2...Second metal pipe, 3
...Electrical insulating tube, 4...Rectangular groove, 5...Fin, 6...Sirisk, 7...Metal block.

Claims (1)

[Claims] A first metal tube having a large number of slanted grooves on the inner surface and one end constricted into a conical or hemispherical shape; This electrically insulated heat pipe is made by joining a squeezed second metal pipe via an electrically insulating cylinder to form a communicating pipe, deaerating the inside, and injecting and sealing a certain amount of electrically insulating liquid.