JP2001108384A - Heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pipe in which a capillary tube force of wick material is increased, a maximum heat transfer power is increased, and a heat transfer can be carried out without producing any dry-out phenomenon even at a relative long distance space or a location having a relative elevational height difference. SOLUTION: There is provided a heat pipe in which wick materials 2 are arranged within a hermetically closed container 1 along its longitudinal direction and working fluid is sealingly filled in it. The wick materials 2 are provided with hollow linear members 3 having hollow circulating flow passages 4 for use in returning the working fluid of liquid phase condensed at a heat radiating section. Substantial wedge-shaped fine clearances 6 for use in returning the working fluid of liquid phase back to a heating segment are formed at least between an outer surface of each of the hollow linear members 3 and an inner wall surface of the hermetically closed container 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe having an improved wick material structure.

[0002]

2. Description of the Related Art A heat pipe is provided by providing a wick material along a longitudinal direction in a closed vessel and enclosing a small amount of working fluid. The working fluid is evaporated in a heating section of one terminal, and the other end is heated. Is a device that condenses in the heat radiating section and performs heat transport by latent heat. At this time, the vapor of the working fluid evaporated in the heating unit (gas phase working fluid) moves to the heat radiating unit due to the pressure difference, but the condensed liquid (liquid phase working fluid) is forced to return to the heating unit by force. is necessary. This force generally utilizes gravity or capillary force. A wick material having a capillary structure is used to generate the capillary force. As a typical wick material, there are a material for forming a groove on the inner wall of a closed container, and a material for installing a metal mesh material or a porous sintered metal. Recently, a wire bundle has been proposed.

[0003]

However, in the case of forming a groove as a wick material, it is difficult to form a groove for increasing a capillary force in a pipe, and it is not easy to increase a capillary force. In addition, a metal mesh material or a porous sintered metal is provided with a larger capillary force than a groove type, but the pressure loss of a working fluid in a liquid phase is increased. If the length is to be increased or a large amount of heat is to be transported particularly from top to bottom (it is necessary to return the liquid-phase working fluid condensed in the lower heat radiating section to the upper heating section)
Dry out phenomenon may occur,
It has been desired to further improve the capillary force. Further, in the case of using the wire bundle, it is necessary to knit the wires with a weft thread crossing the wire bundle and integrate them, and the pressure loss of the liquid-phase working fluid returning to the heating unit at this knot becomes large. However, the flow of the working fluid became poor, and the capillary force could not be similarly increased. As described above, none of the conventional wick materials of the heat pipe can easily increase the capillary force, and cannot improve the heat transport ability.

[0004] The present invention solves the above problems, increases the capillary force of the wick material to increase the maximum heat transport force, and can be used in a relatively long distance section or a place with a relatively high level difference. An object of the present invention is to provide a heat pipe capable of performing heat transport without causing an out phenomenon.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, a heat pipe according to the present invention is provided by providing a wick material along a longitudinal direction in a closed container and sealing a working fluid. The wick material includes a hollow linear body having a hollow reflux passage for returning a liquid-phase working fluid condensed in the heat radiating section to the heating section, and a liquid is provided between at least an outer surface of the hollow linear body and an inner wall surface of the closed container. It is provided so that a minute gap for returning the working fluid of the phase to the heating unit is formed.

Further, it is preferable that the hollow wire is constituted by a hollow stranded wire having a hollow reflux passage.
Further, the closed container is a plate-shaped container having a rectangular or elliptical hole, and the hollow linear body inserted into the hole has an outer diameter substantially equal to the minor diameter of the hole. It is preferable that a minute gap is formed between the outer surface of the hollow linear body and the inner wall surfaces on both short sides of the hole to return the working fluid in the liquid phase to the heating unit. It is.

[0007]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 1A and 1B are a cross-sectional view and a partial vertical cross-sectional view of a heat pipe according to the present invention, and FIG. 2 is a partially enlarged cross-sectional view showing a part of FIG. The wick material 2 is provided along a longitudinal direction in a closed container 1 made of, for example, a circular tubular body, and a working fluid such as water or acetone is sealed.

As shown in detail in FIG. 1B, the wick material 2 is formed, for example, on the outer periphery of a spiral core 5 formed by spirally winding copper and aluminum strips having good heat conductivity by gap winding. In addition, a large number of hollow wires 3 made of a circular hollow single wire made of, for example, copper or aluminum are twisted together, and the central portion of each hollow wire 3 is condensed by the heat radiation portion of one terminal. A hollow recirculation passage 4 for returning the working fluid in the liquid phase to the heating section of the other terminal is formed. Further, between the outer surface of the hollow linear body 3 and the inner wall surface of the closed container 1 and between the hollow linear bodies 3, there are formed substantially wedge-shaped minute gaps 6 for returning the liquid-phase working fluid to the heating unit. It is formed. The spiral core 5 serves to hold the hollow linear body 3 in the closed container 1. Reference numeral 7 denotes a vapor transmission passage for moving the gas-phase working fluid evaporated in the heating unit to the heat radiation unit. When the wick material 2 as described above is used, at least the minute gap 6 formed between the outer surface of the hollow wire 3 and the inner wall surface of the closed container 1 and the hollow reflux formed in the hollow wire 3 Capillary forces are generated from both passages 4. As a result, more liquid-phase working fluid than before can be returned from the heat radiating section (condensing section) to the heating section (evaporating section). When the minute gap 6 is formed in a substantially wedge shape, a large capillary force is generated particularly in a narrow end portion, which is effective.

FIG. 3 shows another embodiment of the heat pipe, in which a plate made of, for example, extruded aluminum is provided with a plurality of rectangular holes 9 arranged in parallel in the width direction. A wick member 10 is provided in each of the holes 9 of the hollow container 8 having an outer diameter substantially equal to the minor diameter of the hole 9 and having a hollow recirculation passage 4 inserted therein. At the four positions between the outer surface of the linear body 3 and the inner wall surfaces on both short sides of the hole 9, small wedge-shaped small gaps 6 for returning the liquid-phase working fluid to the heating unit are formed. It was done. In addition, reference numeral 11 denotes a vapor transmission passage for moving the gas-phase working fluid evaporated in the heating unit to the heat radiation unit. The use of such a wick material 10 eliminates the need for a difficult operation of closely contacting and fixing the wick material made of a metal mesh or a porous sintered metal to the inner wall surface of the hole, and uses a wire bundle. In comparison with the heat pipe, a capillary force can be generated from both the minute gap 6 and the hollow recirculation passage 4, and even in a plate-like heat pipe in which a wick material is difficult to be mounted, many liquid-phase working fluids can be formed. This is preferable because the heat can be efficiently returned to the heating section to increase the heat transport power.

The hollow wire 3 is formed of a single hollow wire, but is not limited to this. For example, as shown in FIG.
It may be formed by twisting aluminum solid wires 13 made of aluminum and forming a hollow wire 12 made of a hollow stranded wire having a hollow reflux passage 14 therein. Although not shown, the hollow stranded wire may have not only a single-layer structure but also a multilayer structure of two or more layers. When the wick material is constituted by such a hollow linear body 12, not only the minute gap 6 formed between the outer surface of the hollow linear body 12 and the closed containers 1 and 8, the hollow reflux passage 14, but also each wick material. Capillary force is also generated from the depressions 13a between the strands 13, and since the strands are stranded, there is no knot connecting the strands, the pressure loss of the working fluid is small, and a larger amount of the working fluid in the liquid phase is discharged from the radiator. The heat can be returned to the heating section, and the heat transport power can be increased.

[0011]

(Embodiment 1) An outer diameter of 9.5 as shown in FIG.
As shown in FIG. 4, 14 solid copper wires 13 having a diameter of 0.16 mm are stranded on the inner wall surface of a tubular sealed container 1 made of a copper pipe having a length of 3 mm and a length of 250 mm. 0.8 mm outside diameter, length 2 having hollow return passage 14
20 hollow linear bodies 12 each made of a 00 mm hollow stranded wire
Although not shown, the spiral core 5 (see FIGS. 1 and 2)
Twisted on the outer periphery of this, and this is inserted into the closed container 1,
A wick material 15 was provided in the closed container along the longitudinal direction by utilizing the spring property of the spiral core. In this case, the hollow linear body 12 is inserted into the closed container 1 and is 30 mm from one end and 20 mm from the other end.
When it enters the back side, it is held and fixed in the sealed container 1, and at least between the outer surface of the hollow linear body 12 and the inner wall surface of the sealed container 1, a substantially wedge for returning the liquid-phase working fluid to the heating unit. A minute gap in the shape of a circle was formed. Further, water as a working fluid was put into the closed container 1 at 15% of the inner volume of the closed container, and both ends were sealed by welding. Thus, a heat pipe was prototyped. The heat pipe is provided with an aluminum block 16 in a range of 50 mm from the one end of the sealed container 1 to form a heating section A, and an aluminum plate (radiation fin) 1 in a range of 100 mm from the other end.
7 was attached to form a heat radiating section B, and a heat insulating material 18 was placed on the outer periphery of the sealed container in an intermediate range of 100 mm to form a heat insulating section C, which was fixed substantially horizontally.

Next, the heating section A of the heat pipe was brought into contact with a heating element (heater) to heat the heating section A. As a result, heat from the heating element is transmitted into the heat pipe via the aluminum block 16, and water (liquid-phase working fluid), which is a working fluid sealed in the heat pipe, evaporates and steam (gas-phase working fluid). Fluid). This vapor moves to the heat radiating section B through the vapor transmission passage 7 (see FIGS. 1 and 2), condenses, and returns to water (liquid-phase working fluid). This condensed water utilizes at least a minute gap formed between the outer surface of the hollow linear body 12 and the inner wall surface of the closed vessel 1, the capillary force generated by the hollow 13a between the hollow reflux passage 14 and the strand 13, and the like. And returns to the heating section A again, so that the wetted edge length of the condensed water is increased and the capillary force is increased as compared with the conventional one, and as a result, the critical circulation amount of the condensed water, which is the working fluid in the liquid phase, is increased. And dry out became difficult to occur.

(Embodiment 2) A rectangular hole 20 having a width of 0.9 mm and a height of 2.2 mm as shown in FIGS.
As shown in FIG. 7, in each of the holes 20 of a plate-shaped closed container 19 made of an extruded aluminum material having a width of 60 mm, a length of 400 mm, and a thickness of 1.9 mm, provided in parallel in a width direction of 24 pieces. The hollow linear bodies 3 each made of a single aluminum hollow wire having a hollow recirculation passage 4 having an outer diameter of 0.82 mm and an inner diameter of 0.5 mm substantially equal to the short diameter (0.9 mm) of the hole 20 are inserted one by one. A wick material 10 is provided, and a substantially wedge-shaped minute liquid for returning the liquid-phase working fluid to the heating unit is provided at four places between the outer surface of the hollow wire 3 and the inner wall surfaces on both short sides of the hole 20. A simple gap 6 is formed. In addition, reference numeral 11 denotes a vapor transmission passage for moving the gas-phase working fluid evaporated in the heating unit to the heat radiation unit. Also, a header (communication portion) 21 that removes about 5 mm of the partition wall portion between the holes from both ends in the longitudinal direction of the sealed container 19 to the back side to allow the hollow reflux passage 4 and the steam flow passage 11 to communicate at both ends. Was provided. Further, 40% of the inner volume of the alternative Freon HCFC123, which is a working fluid, is placed in the sealed container 19, and sealing caps 22 are attached to both ends and sealed by welding. Thus, a prototype heat pipe is manufactured. did. This heat pipe is formed by attaching an aluminum block (not shown) within a range of 100 mm from the one end of the closed vessel 19 to form a heating section A, and attaching an aluminum plate (not shown) within a range of 150 mm from the other end. A heat radiating portion B is formed, and a heat insulating material (not shown) is placed on the outer periphery of the closed container in a middle 150 mm range to form a heat insulating portion C. A was tilted and fixed such that A was tilted 5 degrees upward.

Next, the heating section A of the heat pipe was brought into contact with a heating element (heater) to heat the heating section A. As a result, heat from the heating element is transmitted into the heat pipe, and the alternative Freon (liquid-phase working fluid), which is a working fluid sealed in the heat pipe, evaporates and vapor (gas-phase working fluid)
become. The vapor moves to the heat radiating section B through the vapor flow passage 11, condenses, and returns to alternative Freon (liquid-phase working fluid). The condensed liquid returns to the heating section A again by utilizing the minute gap 6 between the outer surface of the hollow wire 3 and the inner wall surfaces of both short sides of the hole 20 and the capillary force generated by the hollow reflux passage 4. As a result, the wetted edge length of the condensate is longer than that of the conventional one, and the capillary force is larger. As a result, the limit circulation amount of the condensed water, which is the working fluid in the liquid phase, is increased, and dryout is less likely to occur. Was.

(Embodiment 3) As shown in FIGS. 8 (a) and 8 (b), twelve elliptical holes 24 having a width of 2.2 mm and a height of 1 mm are provided in parallel in the width direction. In every other six holes 24A of a plate-shaped closed container 23 made of an extruded aluminum material having a width of 30 mm, a length of 160 mm, and a thickness of 1.5 mm,
As shown in FIG. 4, 14 solid copper wires 13 having a diameter of 0.16 mm are twisted to form a hollow reflux passage 1 therein.
As shown in FIG. 9, two hollow linear bodies 12 each formed of a hollow stranded wire having an outer diameter of 0.8 mm and a length of 150 mm each having a No. 4 are inserted in parallel, and a wick material 25 is provided along the longitudinal direction. An approximately wedge-shaped minute gap 6 for returning the liquid-phase working fluid to the heating section is formed between the outer surface of the hollow linear body 12 and the inner wall surface of the hole 24A. The other six holes 24 </ b> B are used as vapor transmission passages 26 for moving the gas-phase working fluid evaporated in the heating unit to the heat radiation unit. In addition, about 5 mm of the partition between the holes was removed from both ends in the longitudinal direction of the closed container 23 to the back side, and the hollow reflux passage 1 was removed.
4 and a header (not shown) 21 for communicating the steam flow passage 26 at both ends. Further, acetone, which is a working fluid, is filled in the closed container 1 to 25% of the inner volume of the closed container 23.
%, And both ends were sealed by welding. Thus, a heat pipe was prototyped. This heat pipe is a closed vessel 2
3, an aluminum block (not shown) is attached within a range of 30 mm from the one terminal to form a heating section A, and an aluminum plate (not shown) is attached to a 50 mm range from the other terminal to form a heat radiating section B. A heat insulating material (not shown) is put on the outer periphery of the closed container in a range of 80 mm to form a heat insulating portion C
The heating unit A was fixed so as to be horizontal in the width direction and inclined so that the heating unit A was inclined downward by 20 degrees with respect to the heat radiation unit B in the longitudinal direction.

Next, the heating section A of the heat pipe was brought into contact with a heating element (heater) to heat the heating section A. Thereby, heat from the heating element is transmitted into the heat pipe, and the acetone (liquid-phase working fluid), which is a working fluid sealed in the heat pipe, evaporates to vapor (gas-phase working fluid). The vapor moves to the heat radiating section B through the vapor flow passage 26, condenses, and returns to acetone (liquid-phase working fluid). This condensed liquid forms a minute gap 6 between the outer surface of the hollow linear body 12 and the inner wall surfaces on both short sides of the hole 24A and the hollow reflux passage 1.
Since it returns to the heating section A again by utilizing the capillary force generated by 4, the wetted edge length of the condensate is increased and the capillary force is increased as compared with the conventional one, and as a result, the working fluid is in the liquid phase. The critical circulation amount of condensed water increased, and dry-out hardly occurred.

In the above embodiments and examples of the present invention,
As a closed container, a tubular, plate-shaped one was described,
Not only straight pipes and flat pipes, but also bent or swaged parts may be used.Tubes may be not only circular but also rectangular such as ellipses and squares. Not done. The container material is not only copper and aluminum,
It may be made of the alloy material, stainless steel or other materials. Also, the material of the hollow linear body does not need to be the same as that of the closed container if there is no problem in compatibility. The inner diameter of the hollow wire which becomes the hollow reflux passage can be appropriately changed depending on the physical properties of the working fluid. In addition, the normal heat pipe is installed horizontally with the heating part (evaporation part) at the bottom,
It can be installed vertically or diagonally, has a large capillary force, and can easily return the condensate (liquid-phase working fluid) to the heating unit, so it can maintain its function as a heat pipe. Yes, and therefore, the heater may be installed with the heating section at the top (top heat mode). Further, when the hollow wire is formed of a hollow stranded wire, the diameter and the stranded pitch of the wires constituting the stranded wire can be appropriately selected depending on the working fluid and the size of the closed container.

[0018]

As described above, according to the present invention, in a heat pipe in which a wick material is provided along a longitudinal direction in a closed vessel and a working fluid is sealed, the wick material is condensed in a heat radiating portion. A hollow linear body having a hollow recirculation passage for returning the liquid-phase working fluid to the heating unit is provided, and the liquid-phase working fluid is returned to the heating unit at least between the outer surface of the hollow linear body and the inner wall surface of the closed vessel. The minute gap and the hollow linear body formed at least between the outer surface of the hollow linear body 3 and the inner wall surface of the closed container 1 are formed so as to form a minute gap to be formed. Capillary force is generated from both of the hollow reflux passages formed in 3, and the capillary force is increased, so that a larger amount of liquid-phase working fluid can be returned from the heat radiating section to the heating section than conventional ones. . Therefore, the heat transport force can be increased, and the heat can be easily transported without causing a dry-out phenomenon even in a section having a relatively long distance or a place having a relatively high level difference.

Further, when the hollow linear body is formed of a hollow stranded wire having a hollow reflux passage, the minute gap formed between the outer surface of the hollow linear body and the closed vessel and the hollow reflux are formed. Capillary force is generated not only from the passage 14 but also from the hollow between the strands of the hollow stranded wire, so that a larger amount of liquid-phase working fluid can be returned from the heat radiating section to the heating section, thereby increasing the heat transport force. Can be.

Further, the closed container is composed of a plate-like container provided with a plurality of rectangular or oval holes, and the hollow wire inserted into the hole has a diameter smaller than that of the hole. It has a substantially equal outer diameter, and a minute gap for returning the liquid-phase working fluid to the heating unit is formed between the outer surface of the hollow linear body and the inner wall surfaces on both short sides of the hole. In addition to the conventional structure, it is not necessary to perform a difficult work of tightly fixing a wick material made of a metal mesh or a porous sintered metal to the inner wall surface of the hole, as compared with a conventional method using a wire bundle. Even when a plate-like heat pipe in which it is difficult to attach a wick material can generate a capillary force from both the minute gap and the hollow reflux passage, a large amount of liquid-phase working fluid can be efficiently supplied to the heating unit. It can be returned to increase the heat transport power.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a heat pipe according to the present invention, in which (A) is a transverse sectional view and (B) is a partial longitudinal sectional view.

FIG. 2 is a partially enlarged cross-sectional view showing a part of FIG.

FIG. 3 is a partial side view showing another embodiment of the heat pipe according to the present invention.

FIG. 4 is an enlarged cross-sectional view in the case where a hollow wire forming a wick material is formed of a hollow stranded wire.

FIG. 5 is a partially omitted schematic diagram showing a case where the present invention is applied to a tubular heat pipe.

6A and 6B are diagrams showing a case where the present invention is applied to a plate-like heat pipe, wherein FIG.
FIG. 7 is a cross-sectional view taken along line XX of FIG.

FIG. 7 is a partially enlarged transverse sectional view showing a part of FIG.

8A and 8B are diagrams showing a case where the present invention is applied to another plate-shaped heat pipe, wherein FIG. 8A is a schematic plan view, and FIG.
FIG. 3A is an enlarged cross-sectional view taken along line YY of FIG.

FIG. 9 is a partially enlarged cross-sectional view showing a part of FIG.

[Explanation of symbols]

 1, 8, 19, 23 Closed container 2, 10, 15, 25 Wick material 3, 12 Hollow linear body 4, 14 Hollow recirculation passage 5 Spiral core 6 Minute gap 7, 11, 26 Steam transmission passage 9, 20 , 24, 24A, 24B hole 13 element wire 13a depression 16 aluminum block 17 aluminum plate 18 heat insulating material 21 header 22 sealing cap A heating part B heat radiation part C heat insulation part

Claims (3)

[Claims] 1. A heat pipe in which a wick material is provided along a longitudinal direction in a closed container and a working fluid is sealed, wherein the wick material transfers a liquid-phase working fluid condensed in a heat radiating portion to a heating portion. A hollow linear body having a hollow reflux path for returning is provided, and a minute gap for returning the working fluid in the liquid phase to the heating section is formed at least between the outer surface of the hollow linear body and the inner wall surface of the closed vessel. A heat pipe characterized by being provided in a heat pipe. 2. The heat pipe according to claim 1, wherein the hollow wire is formed of a hollow stranded wire having a hollow reflux passage. 3. The closed container is a plate-shaped container provided with a rectangular or oval hole, and a hollow linear body inserted through the hole is substantially equal to a minor diameter of the hole. Having a diameter, between the outer surface of the hollow linear body and the inner wall surfaces on both short sides of the hole, a minute gap for returning the working fluid in the liquid phase to the heating unit is formed. The heat pipe according to claim 1 or 2, wherein