JPH1123169A - Heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the pipe body against damage even when the heating medium in a heat pipe is frozen. SOLUTION: The heat pipe 1 comprises a pipe 2 made of a metallic material encapsulating a heating fluid, e.g. water 3, mixed with solid pieces having sharp edge, e.g. glass pieces 5. Even if the heating fluid begins to be frozen, sharp edge of the solid piece cracks the ice to release the pressure being applied to the pipe wall thus protecting the pipe body against damage. Small acute glass pieces are employed economically and effectively as the solid pieces having sharp edge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a heat pipe.

[0002]

2. Description of the Related Art Heat pipes in which a heat transfer fluid (working fluid) such as water is put into a pipe such as a copper pipe and sealed in a vacuum state have been widely used for cooling electronic equipment and heat exchangers. . As the heat transfer fluid, various substances such as alternative chlorofluorocarbon and alcohol are used in addition to water.

[0003]

For example, when a heat pipe using water as a heat transfer fluid is used in a cold region, the heat transfer fluid inside freezes and expands, and the pressure may cause the pipe to burst. Was. In order to avoid this, it is conceivable to add antifreeze to the fluid, but if this type of additive is added, the heat transfer characteristics of the heat transfer fluid will be significantly reduced, and the efficiency of the heat pipe will be reduced. was there. In addition, if alcohol or chlorofluorocarbon is used instead of water, the problem of rupture can be avoided, but the heat transfer performance of the heat pipe is reduced.

[0004] In view of such circumstances, an object of the present invention is to prevent damage to a tube caused by freezing of the heat transfer fluid.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a heat pipe in which a heat transfer fluid is sealed in a tubular body, wherein a solid piece having a sharp edge is mixed into the heat transfer fluid. It is characterized in that it is provided inside the above-mentioned tubular body.

According to this configuration, even if the heat transfer fluid starts to freeze, the sharp edges of the solid pieces cause cracks in the ice and reduce the pressure on the pipe wall, so that no damage to the pipe body occurs. . As such a solid piece having a sharp edge, it is economical and effective to put, for example, a small piece of glass having a sharp corner.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically based on embodiments of the invention shown in the drawings. FIG.
Represents a specific example of the present invention.
In a pipe 2, an appropriate amount of water 3 as a heat transfer fluid (working fluid) is sealed in a pipe 2 made of a metal material (for example, copper, copper alloy, aluminum alloy, stainless steel, or the like). The space 4 other than water is kept in a vacuum.

In the water 3 as the heat transfer fluid, small glass pieces 5 are mixed as solid pieces, and the glass pieces 5 have sharp edges 5a. The size of the glass piece 5 depends on the diameter of the heat pipe and the like, but is usually about several millimeters in outer diameter. The number of additions may be appropriately selected depending on the size of the heat pipe, etc.
Usually, one or several pieces are sufficient. The solid piece having a sharp edge is not limited to the glass piece in the illustrated example, but may be a sharp piece of metal, stone, synthetic resin, etc., having appropriate hardness and strength not to be easily broken. can do.

FIGS. 2 to 5 are explanatory diagrams when the heat pipe 1 is used in an upright state. When the heat pipe 1 is used at a temperature higher than the freezing point of water, water does not freeze as shown in FIG. Although there is no problem, water used as a heat transfer fluid may freeze when used in cold regions or in winter.

FIG. 3 shows a state in which a part of the water 3 has begun to freeze, and 6 is an ice block. In this state, no problem occurs yet, but when the entire bottom is frozen as shown in FIG. 4, pressure is applied to the tube wall 2a by expansion.

In the conventional heat pipe, the pressure due to such expansion due to freezing increases, so that a large stress acts on the pipe wall and eventually the pipe wall may burst. However, in the present invention, FIGS. As shown, since a solid piece (a glass piece in the illustrated example) 5 having a sharp edge is present in the fluid 3, a crack 7 enters the ice during freezing due to the edge of the solid piece, and internal stress is reduced. Accordingly, the ice block itself cracks and rises, so that the stress applied to the tube wall is reduced, and rupture and deformation are avoided.

In the illustrated example, since the solid piece 5 is mixed in the heat transfer fluid 3 so as to be free to move, the solid piece 5 comes into contact with the pipe wall during movement or the like to generate a sound, There is a risk of wear itself. 6 and 7 show an example in which a solid piece is fixed to the tube wall 2a in order to avoid such a problem. In FIG. 6, the solid piece 5 is fixed directly to the tube wall, but in FIG. 7, the solid piece 5 is fixed to the metal rod 8 rising from the tube wall 2a. As described above, when the solid piece 5 is fixed, there is an advantage that the solid piece 5 is not worn or noise is generated.

When the heat pipe 1 is used, for example, for cooling an insulating substrate IP for an electric circuit, as shown in FIG. 8, the heat pipe 1 is placed near an electric component D that is likely to generate heat, such as a power transistor, a relay, and a fuse. The heat pipe 1 is fixed with an adhesive or the like, and the end of the heat pipe 1 is bonded and fixed to a heat sink R provided outside. The heat generated from the electric components is guided to the outside through the heat pipe 1 and is radiated there, so that the temperature rise of the electric components and the circuit is suppressed.

In the above description, the case where the heat transfer fluid is pure water has been described as an example, but the present invention is similarly effective in the case of other fluids that may freeze.

[0015]

As is apparent from the above description, the heat pipe of the present invention lowers the heat transfer efficiency because a solid piece having a sharp edge is mixed in the heat transfer fluid that may be frozen. Without this, it became possible to prevent the damage to the tube body due to freezing.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a state in which a heat transfer fluid is not frozen.

FIG. 3 is a cross-sectional view illustrating a state at the start of freezing.

FIG. 4 is a cross-sectional view illustrating a state in which freezing has progressed.

FIG. 5 is a cross-sectional view illustrating an operation of a solid piece.

FIG. 6 is an explanatory diagram of a different embodiment.

FIG. 7 is an explanatory diagram of still another embodiment.

FIG. 8 is an explanatory diagram of how to use a heat pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat pipe 2 Tubular body 3 Heat transfer fluid 5 Solid piece 6 Ice 7 Crack

Claims (2)

[Claims] 1. A heat pipe in which a heat transfer fluid is sealed in a tube, wherein a solid piece having a sharp edge is provided inside the tube so as to be mixed into the heat transfer fluid. Heat pipe. 2. The heat pipe according to claim 1, wherein the solid piece having a sharp edge is a glass piece.