JP2005106430A - Loop type heat pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent breakage by providing a thermal elongation difference absorbing part between a wick and an evaporator container for restricting excess force added to the evaporator container and the wick. <P>SOLUTION: The evaporator 1 comprises the wick 9 of a capillary structure comprising a liquid sump space 13 inside to store liquefied working fluid 3 in a hollow cylinder, the evaporator container 8 containing the wick 9, forming a sealed space to seal the working fluid 3, and forming a steam passage 17 to the wick 9 in which vaporized working fluid flows, and support members 15 respectively provided at both end parts of the wick 9 in the evaporator container 8 to support the wick 9 from the evaporator container 8. On at least either of the wick 9, the evaporator container 8, and the support members 15, the thermal elongation difference absorbing part 18 is provided to absorb thermal elongation difference generated based on difference between linear expansion coefficients of the wick 9 and the evaporator container 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a loop type heat pipe that circulates a working fluid between an evaporator provided on a high temperature side and a condenser provided on a low temperature side, thereby transferring heat between the evaporator and the condenser. It is about.

  The loop heat pipe has an evaporator, a condenser, and a circulation path for circulating a working fluid between the evaporator and the condenser. The evaporator is attached to a cooling target such as a heat generating device, vaporizes the working fluid, and cools the cooling target using the heat of vaporization. The condenser cools the working fluid vaporized by the evaporator back to a liquid.

  The evaporator has a long bottomed hollow cylindrical evaporator container and a long hollow cylindrical wick accommodated in the evaporator container. The evaporator container is composed of a cylindrical cylindrical body and two container end plates that seal both ends of the cylindrical body, and the inside is a sealed space.

  The wick has a capillary structure that allows fluid to permeate and has a cylindrical shape that is thick in the radial direction. The wick is sealed at both ends of the cylindrical shape with two wick end plates. The wick and the wick end plate form a liquid storage space in which the working fluid is stored. Between the wick and the evaporator container, a steam channel through which the vaporized working fluid flows is formed.

  A liquid tube extending from the condenser passes through the container end plate on one side of the evaporator container and enters the evaporator container, and further extends through the wick end plate to the inside of the liquid storage space. In addition, a vapor pipe connected to the vapor flow path is connected to the evaporator container, and the vapor pipe extends toward the condenser.

The wick is manufactured by putting a metal fiber such as nickel into a mold and solidifying it into a cylindrical shape, and then sintering the cylinder. In addition, the wick is not limited to metal fibers, and may be produced by sintering metal powder after it is put into a mold and hardened into a cylindrical shape.
Furthermore, it may be produced by sintering non-metallic fibers or powders such as ceramics. When made of ceramic, the sintering temperature is much higher than when made of metal.
On the other hand, the evaporator container that houses the wick needs to be made airtight, and is made of aluminum or the like that is easy to process.

  In the loop heat pipe having such a configuration, the working fluid stored in the liquid storage space of the evaporator penetrates into the wick by capillary force and reaches the surface of the wick. At this time, when heat is transmitted from the outside, the working fluid is vaporized from the surface of the wick. The vaporized working fluid becomes steam in the steam flow path. The generated steam is returned from the steam flow path to the condenser via the steam pipe, cooled by the condenser, and liquefied. The working fluid that has become liquid is returned again to the liquid reservoir space of the evaporator via the liquid pipe. In this way, the working fluid circulates between the evaporator and the condenser, and heat moves accordingly (see, for example, Patent Document 1).

  In the manufacturing process of the loop heat pipe having the above-described configuration, first, the wick, the wick end plate, and the liquid pipe are assembled together. And this assembly is stored in an evaporator container. Thereafter, both ends of the evaporator container are sealed with a container end plate to form an evaporator container sealed.

  In such a manufacturing process, the liquid pipe and the wick end plate are joined by brazing at a portion where the liquid pipe passes through the wick end plate. On the other hand, regarding the part where the liquid pipe penetrates the container end plate, the liquid pipe and the container end plate are joined by welding. Conventionally, there has been a problem that the brazing portion between the liquid pipe and the wick end plate comes off due to heat generated when welding the liquid pipe and the container end plate.

  As a method for solving such a problem without increasing the cost, a method has been proposed in which the wick end plate and the container end plate are separated from each other by a predetermined distance. However, if the distance between the wick end plate and the container end plate is simply separated, the periphery of the liquid pipe becomes a steam flow path in the space formed between the wick end plate and the container end plate. That is, through the wall surface of the liquid pipe, a working fluid of gaseous vapor flows outside the wall surface, and a liquid working fluid flows inside the wall surface.

  And when the circumference | surroundings of a liquid pipe become a steam flow path in this way, the movement of the heat | fever from a gaseous working fluid to a liquid working fluid becomes a problem. This is because when the heat transfer is increased, the original heat transport capability of the heat pipe is reduced.

  As a method for solving this problem, conventionally, in the space between the wick end plate and the container end plate, the outer peripheral wall surface of the liquid pipe is not directly in contact with the steam flow path. There is a proposal to provide a partition (connection pipe).

  Furthermore, proposals have been made to simultaneously provide the partition (connection pipe) with a function of supporting and fixing the wick. That is, in the space between the wick end plate and the container end plate, it is arranged so as to form a substantially tubular shape and cover the liquid tube, one side is fixed to the end of the wick, and the other end is fixed to the container end plate. There has been a proposal to provide a connecting pipe.

  On the other hand, in general, it is effective to make the evaporator structure symmetrical in order to reduce the manufacturing cost. For this reason, it has been proposed to provide the above-mentioned connecting pipes at both ends of the wick in the evaporator container, and to support the wick from both ends with these two connecting pipes.

JP 2000-146471 A

  In the loop heat pipe having such a configuration, the wick and the evaporator container are different from each other in material, so that the linear expansion coefficients thereof are different, and a difference in elongation due to heat occurs between the two as the temperature changes. In the type in which both ends of the wick are firmly supported and fixed from the evaporator container by connecting pipes as in the above proposal, if this difference in elongation due to heat occurs, the wick and the evaporator container Stress is generated. And when this stress became excessive, there existed a problem that the wick produced with the porous body will be damaged. This problem was particularly noticeable when the wick was a brittle material such as ceramic.

  The present invention was made to solve the above-described problems, and an object of the present invention is to obtain a loop heat pipe that prevents excessive force from being applied to the evaporator container and the wick and prevents damage to the equipment. And

  In the loop heat pipe according to the present invention, the evaporator is a hollow wick-shaped wick having a liquid storage space for storing the liquefied working fluid therein, and a sealed space for housing the wick and sealing the working fluid. And an evaporator container that forms a vapor flow path through which the vaporized working fluid flows between the wick and the both ends of the wick in the evaporator container, and supports that support the wick from the evaporator container The thermal expansion difference absorption part which absorbs the thermal expansion difference which generate | occur | produces by the difference in the linear expansion coefficient of a wick and an evaporator container was provided in at least any one of a wick, an evaporator container, and a supporting member.

  In the present invention, since the thermal expansion difference absorbing portion that absorbs the difference in thermal expansion generated by the difference in linear expansion coefficient between the wick and the evaporator container is provided in at least one of the wick, the evaporator container, and the support member, It is suppressed that an excessive force is applied to the container and the wick, and damage is prevented.

Embodiment 1 FIG.
FIG. 1 is a system diagram showing the overall configuration of a loop heat pipe. In FIG. 1, the loop heat pipe has an evaporator 1 provided on the high temperature side, a condenser 2 provided on the low temperature side, and a steam pipe 4 and a liquid pipe 5 connecting the two. A working fluid 3 is enclosed in a sealed circulation path formed by the evaporator 1, the condenser 2, the vapor pipe 4 and the liquid pipe 5. Then, the working fluid 3 circulates between these devices as indicated by arrows in the figure. The steam pipe 4 and the liquid pipe 5 constitute a circulation path for circulating the working fluid between the evaporator 1 and the condenser 2. The working fluid 3 vaporized by the evaporator 1 is liquefied by the condenser 2. In other words, the working fluid 3 circulates between the evaporator 1 and the condenser 2 and repeats the change between the two states of the gas working fluid 3a and the liquid working fluid 3b.

  A heat generating device 6 as an object to be cooled that is cooled by the loop heat pipe is disposed on the outer peripheral surface of the evaporator 1 in contact with an area sufficient for heat exchange (in FIG. 1, heat is generated). The device 6 is simplified and only a part is shown).

  FIG. 2 is a longitudinal sectional view of the evaporator 1 of FIG. 1 showing Embodiment 1 of the loop heat pipe of the present invention. 3 is a cross-sectional view taken along line III-III in FIG. The evaporator 1 has a long bottomed hollow cylindrical evaporator container 8 and a long hollow cylindrical wick 9 concentrically housed inside the evaporator container 8. The evaporator container 8 includes a cylindrical body 8a and container end plates 8b and 8c that seal both ends of the cylinder 8a, and the inside is a sealed space. The evaporator container 8 is made of aluminum or stainless steel.

  The wick 9 has a cylindrical shape that is thick in the radial direction. Eight steam grooves 11 extending over the entire length in the longitudinal direction are formed on the outer peripheral surface of the wick 9. The outer peripheral surface of the wick 9 other than the steam groove 11 is in contact with the inner peripheral surface of the evaporator container 8. The eight steam grooves 11 are formed at equal intervals in the circumferential direction and parallel to each other in the axial direction. The steam groove 11 forms a space extending in the longitudinal direction between the wick 9 and the evaporator container 8. This space constitutes a part of the vapor flow path 17 through which the vaporized (evaporated) working fluid 3a flows. The space inside the cylindrical wick 9 constitutes a part of the liquid storage space 13 in which the liquid working fluid 3b is stored.

The wick 9 is manufactured by putting metal fibers such as nickel, stainless steel, titanium, etc. into a mold and solidifying the cylinder, and then sintering the cylinder. With respect to this sintering, the metal fibers are heated so that the fiber shape remains and the cylindrical shape is maintained without completely melting the metal fiber. Specifically, the metal fibers near the surface of the cylinder are heated to such an extent that only adjacent portions in contact with each other are welded to each other. The wick 9 manufactured in this way is a porous body in which countless passages having a diameter of about 1 to several tens of microns are formed inside, and has a capillary structure that allows liquid to penetrate. That is, the wick 9 permeates the working fluid throughout by the capillary force.
The wick 9 is not limited to fibers but may be made by sintering after metal powder is put into a mold and hardened into a cylindrical shape. In some cases, non-metallic fibers (whisker fibers) such as ceramics or powders are sintered. When made of ceramic, the sintering temperature is very high.

A liquid pipe 5 extending from the condenser 2 (FIG. 1) passes through the container end plate 8 b on one side of the evaporator container 8 and extends into the liquid storage space 13. The liquid pipe 5 extends over substantially the entire length of the evaporator container 8 in the liquid storage space 13.
In order to make the explanation easier to understand, the container end plate into which the liquid pipe 5 of the evaporator 1 enters is the liquid pipe side container end plate 8b, and the container end plate on the opposite side is the anti-liquid pipe side container end plate. 8c.
In the liquid pipe 5, an opening is formed in the side wall surface at a position slightly on the side opposite to the liquid-liquid-side container end plate 8 c from the center of the liquid storage space 13. This opening is an outlet 5a through which the liquid working fluid 3b flows out.

  The wick 9 is shorter than the evaporator container 8 in the longitudinal direction. A space having a predetermined width is formed at both ends of the wick 9 inside the evaporator container 8. Connection pipes 15 are disposed in both spaces. The connecting pipe 15 serves to support the wick 9 from the evaporator container 8. The connecting pipe 15 is made of aluminum or stainless steel. A sealed space formed between the outer peripheral surface of the connection pipe 15 and the evaporator container 8 constitutes a steam flow path 17 through which the working fluid 3a vaporized (evaporated) flows together with the steam groove 11 described above. . On the other hand, the space inside the connecting pipe 15 constitutes a liquid storage space 13 that stores the liquefied working fluid 3b together with the space inside the wick 9. The steam pipe 4 is connected to the liquid pipe side container end plate 8 b side end of the cylindrical body 8 a of the evaporator container 8 so as to communicate with the steam flow path 17. In the middle portion of the connecting pipe 15, a cross-sectionally U-shaped thin plate member 18 (thermal elongation difference absorbing portion) which is an elastic member is provided. The cross-sectionally U-shaped thin plate member 18 absorbs the difference in elongation due to heat generated by the difference in linear expansion coefficient between the wick 9 and the evaporator vessel 8, that is, the difference in thermal elongation.

  FIG. 4 is an enlarged view of the end portion on the liquid tube side container end plate 8b side of the evaporator container 8 of FIG. 2 (in FIG. 4, the steam pipe 4 is omitted). In FIG. 4, the connection pipe 15 has a large diameter cylindrical portion 15a and a small diameter cylindrical portion 15b having a smaller diameter than the large diameter cylindrical portion 15a. The large diameter cylindrical portion 15a has a base portion sealed and joined to an end portion of the wick 9, and a distal end extending in the direction of the liquid tube side container end plate 8b. The base of the small diameter cylindrical portion 15 b is sealed and joined to the liquid tube side container end plate 8 b of the evaporator container 8, and the tip extends in the wick 1 direction. The large-diameter cylindrical portion 15a and the small-diameter cylindrical portion 15b are arranged so that their distal ends overlap in the radial direction. And the front-end | tip of the large diameter cylindrical part 15a is sealed and joined to the outer peripheral surface intermediate part of the small diameter cylindrical part 15b by the joining flange part 15c formed extending in the center direction from the front-end | tip edge. The distal end of the small-diameter cylindrical portion 15b is sealed and joined to the outer peripheral surface of the liquid pipe 5 by a joining flange portion 15d formed extending from the distal end edge in the center direction. With such a structure, a cylindrical space portion 20 is formed between the small diameter cylindrical portion 15 b and the liquid pipe 5. The space portion 20 communicates with a space outside the evaporator 1 and the inside is filled with air. Therefore, the space part 20 has heat insulation. The space 20 suppresses conduction of heat from the gas working fluid 3 a in the vapor flow path 17 to the liquid working fluid 3 b in the liquid pipe 5.

  The large-diameter cylindrical portion 15a of the connecting pipe 15 is once divided into two at a plane orthogonal to the axis at the intermediate portion. The two divided surfaces are sealed and connected so that the ring-shaped thin plate member 18 having an annular cross section is sandwiched therebetween. The cross-section of the U-shaped thin plate member 18 forms a cross-section of a U-shape over the entire circumference. Specifically, the cross-sectionally U-shaped thin plate member 18 has a shape in which two tapered rings are joined to each other with a large-diameter portion, and the central corner of the cross-sectionally U-shaped cross section is around the entire circumference. It has a shape that makes one round while facing outward. The cross-sectionally U-shaped thin plate member 18 is joined by sealing both opening edge portions corresponding to the small diameter portion of the taper to the dividing surface of the connecting pipe 15. The cross-sectionally U-shaped thin plate member 18 is made of aluminum or stainless steel. The cross-sectionally U-shaped thin plate member 18 is made thinner than the thinnest part of the other part of the connection pipe 15 and is formed in a cross-section of a U-shape, so that the connection pipe 15 has a predetermined axial size. When the power is added, it deforms the fastest. And, when the difference in thermal expansion occurs between the wick 9 and the evaporator vessel 8 due to the difference in coefficient of linear expansion, the cross-sectionally U-shaped thin plate member 18 is other than the cross-shaped U-shaped thin plate member 18. , The evaporator container 8 and the wick 9 are deformed earlier. Thereby, the cross-sectionally U-shaped thin plate member 18 absorbs the difference in thermal expansion generated by the difference in linear expansion coefficient between the wick 9 and the evaporator container 8.

  Next, the operation of the loop heat pipe will be described. The heat conducted from the heating device 6 to the evaporator 1 is transmitted to the evaporator container 8. This heat evaporates the liquid working fluid 3 b from the inner surface of the vapor groove 11 of the wick 9. The working fluid 3a which has become a gas flows into the condenser 2 (FIG. 1) via the steam flow path 17 and the steam pipe 4. The gaseous working fluid 3a flowing into the condenser 2 is cooled and condensed by the condenser 2, and liquefied to become a liquid working fluid 3b.

  The liquid working fluid 3 b returns to the evaporator 1 through the liquid pipe 5. The liquid working fluid 3 b returned to the evaporator 1 is accumulated in the liquid storage space 13. The liquid working fluid 3 b is carried to the inner surface of the vapor groove 11 by the capillary force of the wick 9. The liquid working fluid 3b is vaporized by the heat absorbed by the evaporator 1 and becomes a gaseous working fluid 3a.

  In the loop heat pipe configured in this way, when the temperature of the evaporator 1 changes, a difference in thermal expansion proportional to the difference in linear expansion coefficient occurs between the evaporator container 8 and the wick 1. Usually, the strength of the wick 1 which is a porous body is weaker than that of the evaporator vessel 8 which is a solid, and the wick 1 breaks when the stress due to the difference in thermal elongation becomes larger than the strength of the wick 1. However, in the present embodiment, since the cross-sectionally U-shaped thin plate member 18 that is a thermal expansion difference absorbing portion is provided in the connecting pipe 15, the thermal expansion difference is absorbed by the cross-shaped U-shaped thin plate member 18. . For this reason, the wick 1 and the evaporator container 8 are not subjected to stress of a predetermined magnitude or more. Thereby, even if a difference in thermal expansion occurs, none of the members are destroyed, and the reliability of the loop heat pipe is improved.

  Moreover, the thermal expansion difference absorption part of this Embodiment is the cross-sectionally U-shaped thin plate member 18 (expandable member) which can be expanded-contracted in the axial direction of the wick 9 and the evaporator container 9. Therefore, the stress due to the difference in thermal elongation is absorbed smoothly without difficulty and the reliability is improved.

  Furthermore, the elastic member of the present embodiment is a U-shaped thin plate member 18 in cross section. Therefore, a structure that can expand and contract in the axial direction of the wick 9 and the evaporator container 8 can be realized at low cost. Further, the rigidity of the connecting pipe 15 is not reduced more than necessary, and the structure is stable.

  Furthermore, in the present embodiment, the support member that supports the wick 9 from the evaporator container 8 is a connection pipe 15 provided so as to partition the liquid storage space 13 and the steam flow path 17. Therefore, the movement of heat from the gaseous working fluid 3a in the vapor channel 17 to the liquid working fluid 3b in the liquid pipe 5 is suppressed, and a high-performance heat pipe can be obtained.

Embodiment 2. FIG.
FIG. 5 is a partial longitudinal sectional view of an evaporator container showing a second embodiment of the loop heat pipe of the present invention. In the present embodiment, the cylindrical body 8a of the evaporator container 8 is once divided by a plane perpendicular to the axis at a position close to the container end plates 8b and 8c. The two divided surfaces are sealed and connected so as to sandwich an annular cross-section thin plate member 22 (thermal expansion difference absorbing portion) which is an elastic member. The cross-sectionally U-shaped thin plate member 22 is a ring-shaped member having a cross-sectionally U-shaped shape over the entire circumference, like the cross-sectionally U-shaped thin plate member 18 of the first embodiment. The cross-sectionally U-shaped thin plate member 22 is joined with both opening edges sealed to the two divided surfaces of the evaporator container 8. The cross-sectionally U-shaped thin plate member 22 is made of aluminum or stainless steel. The cross-sectionally U-shaped thin plate member 22 is more easily deformed than portions other than the cross-sectionally U-shaped thin plate member 22 of the evaporator container 8.

  In the loop heat pipe of the present embodiment, the evaporator container 8 is formed in a cross-sectionally-shaped thin plate member 22 in which a part of the cylindrical body 8a is a differential thermal absorption portion. The cross-sectionally U-shaped thin plate member 22 absorbs the difference in thermal expansion generated by the difference in linear expansion coefficient between the wick 9 and the evaporator container 8. Therefore, excessive stress is suppressed from being generated in the portion other than the cross-section of the cross-section of the evaporator container 8, the wick 9, and the connecting pipe 15. Thereby, destruction of the evaporator container 8, the wick 9, and the connecting pipe 15 is suppressed.

Embodiment 3 FIG.
FIG. 6 is a partial longitudinal sectional view of an evaporator container showing a third embodiment of the loop heat pipe of the present invention. In the present embodiment, the wick 9 is once divided by a plane perpendicular to the axis, and the two divided surfaces sandwich an annular cross-section thin plate member 23 (thermal expansion difference absorbing portion) that is an elastic member. It is sealed and connected. The cross-sectionally U-shaped thin plate member 23 is formed in a cross-sectionally U-shaped thin plate member 18 in the same manner as the cross-sectionally U-shaped thin plate member 18 of the first embodiment and the cross-sectionally U-shaped thin plate member 22 of the second embodiment. Is an annular member. In the cross-sectionally U-shaped thin plate member 23, both opening edges are joined to two divided surfaces of the wick 9, respectively. The cross-sectionally U-shaped thin plate member 23 is made of aluminum or stainless steel. The cross-sectionally U-shaped thin plate member 23 serving as a thermal expansion difference absorbing portion absorbs a thermal expansion difference generated by a difference in linear expansion coefficient between the wick 9 and the evaporator container 8. Also in this embodiment, the same effect as in Embodiments 1 and 2 can be obtained.

Embodiment 4 FIG.
FIG. 7 is a partial longitudinal sectional view of an evaporator container showing Embodiment 4 of the loop heat pipe of the present invention. In the present embodiment, a bellows 25 (thermal expansion difference absorbing portion), which is an expansion / contraction member, is disposed in place of the cross-sectionally U-shaped thin plate member 18 of the first embodiment. That is, the large-diameter cylindrical portion 15a of the connecting pipe 15 is once divided into two at a surface orthogonal to the axis at the intermediate portion, and the two divided surfaces are sealed and sandwiched so as to sandwich the bellows 25. The bellows 25 is made of aluminum or stainless steel, and easily expands and contracts by an axial force. Thereby, the bellows 25 absorbs the difference in thermal expansion generated by the difference in linear expansion coefficient between the wick 9 and the evaporator container 8. Therefore, even if a difference in thermal expansion occurs, none of the members are destroyed, and the reliability of the loop heat pipe is improved.

  In the present embodiment, since the bellows 25 is used as the expansion / contraction member, it is possible to easily realize a structure that can expand and contract in the axial direction of the wick 9 and the evaporator container 9. Further, the stress due to the difference in thermal elongation is absorbed smoothly without difficulty, and the reliability is improved.

Embodiment 5 FIG.
FIG. 8 is a partial longitudinal sectional view of an evaporator container showing Embodiment 5 of the loop heat pipe of the present invention. In the loop heat pipe of the present embodiment, the container end plate of the evaporator container 8 is thinned in the axial direction to form a thin plate container end plate 26 (thermal elongation difference absorbing portion) which is a thin portion. Yes. While the normal container end plate is 1 to 3 mm, the thin plate container end plate 26 of the present embodiment is 0.3 to 0.5 mm.

  When a difference in thermal expansion occurs between the wick 9 and the evaporator vessel 8 due to a difference in coefficient of linear expansion, the thin plate container end plate 26 is any of the cylindrical body 8a, the wick 9 and the connecting pipe 15 of the evaporator vessel 8. Deform before. Thereby, the thin plate container end plate 26 absorbs the thermal expansion difference generated by the difference in the linear expansion coefficient between the wick 9 and the evaporator vessel 8. Therefore, even if a difference in thermal expansion occurs, none of the members are destroyed, and the reliability of the loop heat pipe is improved.

Embodiment 6 FIG.
FIG. 9 is a partial longitudinal sectional view of an evaporator container showing Embodiment 6 of the loop heat pipe of the present invention. In the connection pipe 15 which is a support member of the wick 9 of the present embodiment, the connection flange portion of the large-diameter cylindrical portion 15a of the connection pipe 15 is thinned in the axial direction, and the thin plate connection flange portion 27 which is a thin wall portion. (Thermal elongation difference absorption part) is formed. While the normal connection flange portion is 1 to 2 mm, the thin plate connection flange portion 27 of the present embodiment is 0.2 to 0.4 mm.

  The thin plate connection flange portion 27 is a portion other than the thin plate connection flange portion 27 of the connection pipe 15 when the difference in thermal expansion occurs between the wick 9 and the evaporator vessel 8 due to the difference in linear expansion coefficient, the evaporator vessel 8, And it deform | transforms before any of the wicks 9. Thereby, the thin plate container end plate 26 absorbs the difference in thermal elongation between the wick 9 and the evaporator vessel 8. Therefore, even if a difference in thermal expansion occurs, none of the members are destroyed, and the reliability of the loop heat pipe is improved.

Embodiment 7 FIG.
FIG. 10 is a partial longitudinal sectional view of an evaporator container showing a seventh embodiment of the loop heat pipe of the present invention. The large-diameter cylindrical portion of the connecting pipe 15 that is a support member of the wick 9 of the present embodiment is divided into two cylindrical portions. That is, the large diameter cylindrical portion of the connecting pipe 15 is divided into a small cylindrical portion 28a having a small diameter and a large cylindrical portion 28b having a large diameter. The small cylindrical portion 28a and the large cylindrical portion 28b are arranged so as to overlap each other by a predetermined length in the axial direction. Two O-rings 28c, which are sealing members, are sandwiched between the two cylindrical portions 28a and 28b. The two O-rings 28c seal between the small cylindrical portion 28a and the large cylindrical portion 28b. With such a structure, the two cylindrical portions 28a and 28b are slidable in the axial direction while being sealed with each other.

When the vaporized working fluid 3a leaks from the vapor flow path 17 to the liquid storage space 13, the heat transport capability of the loop heat pipe decreases. Therefore, the two O-rings 28c are arranged so as to be double in the direction in which the working fluid 3a tends to leak so that the working fluid 3a does not leak to the liquid storage space 13 side.
The O-ring 28c is fitted in an O-ring groove formed on the outer peripheral surface of the small cylindrical portion 28a over the entire circumference, and movement in the axial direction is suppressed. The small cylindrical portion 28a, the large cylindrical portion 28b, and the O-ring 28c constitute the thermal expansion difference absorbing portion of the present embodiment.

  In the loop heat pipe of the present embodiment, the large-diameter cylindrical portion of the connecting pipe 15 is divided into two cylindrical portions 28a and 28b, and can slide in the axial direction. Therefore, the wick 9 and the evaporator It is possible to absorb the difference in thermal expansion generated by the difference in linear expansion coefficient with the container 8.

Embodiment 8 FIG.
FIG. 11 is a partial longitudinal sectional view of an evaporator container showing an eighth embodiment of the loop heat pipe of the present invention. In the present embodiment, the liquid pipe 5 is bent at a right angle at the end of the evaporator 1. Along with this, the large-diameter cylindrical portion 15e of the connecting pipe 15 as a support member is also bent at a right angle. Furthermore, the end portion 8d of the cylindrical portion 8a of the evaporator container 8 is also bent at a right angle. Therefore, the small diameter cylindrical portion 15 b of the connection pipe 15 extends in a direction orthogonal to the axis of the evaporator 1.

  In general, when a force acts from a direction orthogonal to the tube, the tube is deformed with a force smaller than a force acting in the longitudinal direction on the tube. In the present embodiment, when the temperature of the evaporator container 8 changes and a difference in thermal expansion occurs between the wick 9 and the evaporator container 8, the generated stress is, for example, the small diameter cylindrical portion 15b of the connecting pipe 15 Acts in a direction perpendicular to the axis. That is, when the wick 9 extends with respect to the evaporator container 8, the upper side in FIG. 11 of the small diameter cylindrical portion 15 b is pushed rightward in FIG. 11, and the wick 9 contracts with respect to the evaporator container 8. The upper side of FIG. 11 of the small diameter cylindrical portion 15b is pulled in the left direction of FIG. The small-diameter cylindrical portion 15b, which is a portion extending at a right angle to the evaporator container 8 and the wick 9, constitutes the thermal expansion difference absorbing portion of the present embodiment.

  In the loop heat pipe of the present embodiment, the connection pipe 15 is bent at a right angle, and the small-diameter cylindrical portion 15b of the connection pipe 15 extends in a direction perpendicular to the evaporator container 8 and the wick 9, so that the evaporation When the temperature of the vessel 8 changes and a difference in thermal elongation occurs between the wick 9 and the evaporator vessel 8, the small diameter cylindrical portion 15b is elastically deformed to absorb the difference in thermal elongation. Therefore, even if a difference in thermal expansion occurs, none of the members are destroyed, and the reliability of the loop heat pipe is improved.

Embodiment 9 FIG.
FIG. 12 is a partial longitudinal sectional view of an evaporator container showing a ninth embodiment of the loop heat pipe of the present invention. In the present embodiment, in the loop heat pipe of the eighth embodiment, a part of the small-diameter cylindrical portion 15b of the connection pipe 15 that is a support member is a bellows 27 (thermal expansion difference absorption portion) that is an expandable member. . That is, the small-diameter cylindrical portion 15b is divided into two at a plane orthogonal to the axis at the intermediate portion, and the two divided surfaces are sealed and sandwiched so as to sandwich the bellows 27. The bellows 27 is made of aluminum or stainless steel, and easily expands and contracts by an axial force. As a result, the bellows 27 absorbs the difference in thermal expansion generated by the difference in linear expansion coefficient between the wick 9 and the evaporator container 8. Thereby, even if a difference in thermal expansion occurs, none of the members are destroyed, and the reliability of the loop heat pipe is improved.

Embodiment 10 FIG.
FIG. 13 is a partial longitudinal sectional view of an evaporator container showing Embodiment 10 of the loop heat pipe of the present invention. In the present embodiment, instead of the bellows 25 of the fourth embodiment, first and second bellows 30a, 30b (thermal expansion difference absorbing portions) that are doubled in the radial direction are provided as elastic members. Yes. Flange portions 30c and 30d are formed to extend radially outward from a joint portion between the first bellows 30a and the large-diameter cylindrical portion 15a. The second bellows 30b is supported by the flange portions 30c and 30d. A heat insulating space 30e is formed between the first and second bellows 30a and 30b.

  In the present embodiment, the heat insulating space 30e is a sealed space, and the inside is evacuated. That is, the heat insulating space 30 e forms a cylindrical vacuum space around the liquid reservoir space 13. This vacuum space functions to suppress heat transfer between the liquid storage space 13 and the steam flow path 17.

  In the evaporator 1, when heat is transferred from the vapor working fluid flowing in the vapor flow path 17 to the liquid working fluid in the liquid storage space 13, heat transport from the evaporator 1 to the condenser 2 is halved, and the loop type The heat transport capacity of the heat pipe is reduced.

  There is a heat conduction path from the outer surface to the inner surface of the connection pipe 15 as one of the paths of heat generated separately from the intended one. When there is a temperature difference between the outer surface and the inner surface of the connection pipe 15, the magnitude of the amount of heat that moves is proportional to the heat flow cross-sectional area (cross-sectional area orthogonal to the heat transfer direction) and the thermal conductivity of the connection pipe 15, It is inversely proportional to the heat transfer distance.

  For example, when the bellows 25 is provided as the thermal expansion difference absorbing portion as in the fourth embodiment, the heat flow cross-sectional area increases, so the amount of heat to move increases and the heat transport capability decreases. In order to improve this point, in the loop heat pipe of the present embodiment, the bellows has a double structure, and a vacuum heat insulating space 30e is formed between the two bellows 30a and 30b. Thereby, the heat transfer which was not intended is suppressed and the favorable heat transport capability is acquired.

  In the loop heat pipe of the present embodiment, since the heat insulating space 30e is configured by the double-structured bellows 30a and 30b which are thermal expansion difference absorbing portions, the difference in linear expansion coefficient between the wick 9 and the evaporator container 8 Can absorb the difference in thermal expansion generated by the steam, and can suppress the transfer of heat from the working fluid of the steam flowing through the steam flow path 17 to the working fluid of the liquid in the liquid storage space 13. A heat pipe can be realized.

  In addition, although the heat insulation space 30e of this Embodiment is made into the vacuum, it is not restricted to this, For example, the heat insulation which is a chemically stable substance with low heat conductivity like nitrogen gas and argon gas When an object is enclosed, a higher heat insulating effect can be obtained.

Embodiment 11 FIG.
FIG. 14 is a partial longitudinal sectional view of an evaporator container showing an eleventh embodiment of the loop heat pipe of the present invention. In the present embodiment, bellows portions of double-structured bellows 31a and 31b (thermal expansion difference absorbing portions) that are elastic members are provided at different positions in the axial direction so as not to overlap each other in the radial direction. . Therefore, the outer diameter of the outer bellows 31a can be reduced. And the dimension increase of the radial direction of the evaporator container 8 can be suppressed. Other configurations are the same as those of the tenth embodiment.

Embodiment 12 FIG.
FIG. 15 is a partial longitudinal sectional view of an evaporator container showing Embodiment 12 of the loop heat pipe of the present invention. In the present embodiment, out of the two bellows 32a, 32b (thermal expansion difference absorbing portion) having a double structure as an elastic member, a small-diameter air hole 32c is formed in the outer bellows 32a. The air hole 32c communicates the heat insulating space 32e formed between the two bellows 32a and 32b having a double structure and the steam flow path 17.

  During the operation of the heat pipe, the working fluid evaporated from the wick 9 moves to the steam pipe 4 through the steam flow path 17. At this time, under the condition that the temperature of the connecting pipe 15 is lower than the saturation temperature of the steam, the steam is cooled by the connecting pipe 15 and condensed on the surface of the connecting pipe 15 to form water droplets. Since the latent heat generated by the condensation of the working fluid moves to the inner surface of the connection pipe 15, the amount of heat transferred from the steam flow path 17 to the liquid storage space 13 increases, and the heat transport capability of the heat pipe is temporarily increased. descend.

  In the present embodiment, the working fluid evaporated through the air holes 32c enters the heat insulating space 32e formed by the double structure bellows 32a, 32b. The evaporated working fluid is condensed on the surface of the inner bellows 32b to form water droplets. These water droplets are connected to each other to form a liquid film. This liquid film is held in the heat insulating space 32e without dripping from the bellows 32b by the action of surface tension because the heat insulating space 32e is closed to some extent. The insulating fluid 32e is filled with the working fluid that has been changed to liquid after this phenomenon. As described above, when the liquid working fluid is held in the heat insulating space 32e, the working fluid has a heat insulating action, so that further condensing of the working fluid that has become vapor to the surface of the connection pipe 15 is suppressed. And the amount of heat leaked from the steam flow path 17 to the liquid storage space 13 is reduced, and the deterioration of the heat transport characteristics of the heat pipe is suppressed.

  In the loop heat pipe having such a structure, the heat insulation between the steam flow path 17 and the liquid storage space 13 can be improved without evacuating the heat insulation space 32e or enclosing gas. This can not only make the structure simple and inexpensive, but also the double structure bellows breaks during use of the heat pipe, impairing the heat insulation capability, or the enclosed gas leaks into the heat pipe In this way, it is possible to eliminate problems such as a decrease in heat transport capacity.

Embodiment 13 FIG.
FIG. 16 is a partial longitudinal sectional view of an evaporator container showing a thirteenth embodiment of the loop heat pipe of the present invention. In the present embodiment, small-diameter air holes 33c and 33d are formed in flange portions 30c and 30d that support two bellows 30a and 30b (thermal expansion difference absorbing portions) having a double structure, which are elastic members, respectively. .
Other configurations are the same as those in the twelfth embodiment.

  Even if air holes 33c and 33d are provided in portions other than the bellows 30a to allow communication between the heat insulating space 32e and the steam flow path 17 as in the present embodiment, the same effect as in the twelfth embodiment can be obtained. .

Embodiment 14 FIG.
FIG. 17 is a partial longitudinal sectional view of an evaporator container showing a fourteenth embodiment of the loop heat pipe of the present invention. In the present embodiment, air holes 33c and 33d are formed in the flange portions 30a and 30b that support the two bellows 31a and 31b (thermal expansion difference absorbing portions) having the double structure of the eleventh embodiment, respectively. The effect similar to that of the twelfth embodiment can be obtained even in the loop heat pipe having such a configuration.

Embodiment 15 FIG.
FIG. 18 is a partial longitudinal sectional view of an evaporator container showing a fifteenth embodiment of the loop heat pipe of the present invention. In the present embodiment, an air hole 35 is formed in a portion other than the bellows portion of the outer bellows 31b out of the two bellows 31a and 31b (thermal expansion difference absorbing portion) having the double structure of the eleventh embodiment. Yes. The effect similar to that of the twelfth embodiment can be obtained even in the loop heat pipe having such a configuration.

Embodiment 16 FIG.
FIG. 19 is a partial vertical sectional view of an evaporator container showing Embodiment 16 of the loop heat pipe of the present invention. In the present embodiment, a wire mesh 36 is provided around the entire circumference of the bellows 25 (thermal elongation difference absorbing portion) that is an elastic member. The metal mesh 36 has a cylindrical shape, is supported by flange portions 30 c and 30 d that extend radially outward from the connection portion of the bellows 25, and is provided so as to cover the bellows 25. A heat insulating space 32 e is formed between the bellows 25 and the wire mesh 36. The working fluid 3a of the steam that has entered the heat insulating space 32e from the wire mesh 36 is condensed on the surface of the bellows 25 as in the twelfth embodiment to become a liquid. This liquid is held in the heat insulating space 32e by the surface tension. The effect similar to that of the twelfth embodiment can be obtained even in the loop heat pipe having such a configuration.

  In Embodiments 1 to 16, the support member that supports the wick 9 from the evaporator container 8 is the connecting pipe 15. However, the support member is not particularly limited to the connection pipe 15 as long as it is a member that supports the wick 9 from the evaporator container 8. For example, a rod that is erected on the container end plates 8 b and 8 c and extends in the direction of the wick 9 may be fixed to the end of the wick 9. Even in such a case, the effect of the present invention can be obtained if at least one of the wick 9, the evaporator container 8, and the rod as the support member is provided with a thermal expansion difference absorbing portion. And when a support member is such a rod, it cannot be overemphasized that the wick end plate similar to the past is provided in the edge part of the wick 9. As shown in FIG.

It is a systematic diagram which shows the whole structure of a loop type heat pipe. It is a longitudinal cross-sectional view of the evaporator part of FIG. 1 which shows Embodiment 1 of the loop type heat pipe of the present invention. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. It is an enlarged view of the container end plate side end part of the evaporator container of FIG. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 2 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 3 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 4 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 5 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 6 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 7 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 8 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 9 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 10 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 11 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 12 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 13 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 14 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 15 of the loop type heat pipe of this invention. It is a partial longitudinal cross-sectional view of the evaporator container which shows Embodiment 16 of the loop type heat pipe of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Evaporator, 2 Condenser, 4 Steam pipe (circulation path), 5 Liquid pipe (circulation path), 8 Evaporator container, 9 Wick, 11 Steam groove, 13 Liquid storage space, 15 Connection pipe (support member), 15b Small-diameter cylindrical part (thermal expansion difference absorption part), 17 Steam flow path, 18, 22, 23 Cross-section-shaped thin plate member (expandable member: thermal expansion difference absorption part), 25, 29 Bellows (expandable member: differential thermal expansion) Absorption part), 26 Thin plate container end plate (thermal elongation difference absorption part), 27 Thin plate connection flange part (thermal elongation difference absorption part), 28a Small cylindrical part (thermal elongation difference absorption part), 28b Large cylindrical part (thermal elongation difference) Absorption part), 28c O-ring (thermal expansion difference absorption part), 30e heat insulation space, 30a, 30b, 31a, 31b, 32a, 32b bellows (expandable member: heat expansion difference absorption part), 32e heat insulation space, 36 wire mesh.

Claims (11)

A loop type heat pipe having an evaporator, a condenser, and a circulation path for circulating a working fluid between the evaporator and the condenser, wherein the working fluid vaporized by the evaporator is liquefied by the condenser; ,
The evaporator is
A capillary structure wick having a liquid storage space for storing a working fluid liquefied in a hollow cylindrical shape;
An evaporator container that houses the wick and forms a sealed space that seals the working fluid, and forms a vapor channel through which the working fluid vaporized flows between the wick and the wick;
Provided at both ends of the wick in the evaporator container, and supporting members for supporting the wick from the evaporator container;
At least one of the wick, the evaporator container, and the support member is provided with a thermal expansion difference absorbing portion that absorbs a difference in thermal expansion caused by a difference in linear expansion coefficient between the wick and the evaporator container. Features a loop heat pipe. The loop heat pipe according to claim 1, wherein the thermal expansion difference absorbing portion is an elastic member that can expand and contract in an axial direction of the wick and the evaporator container. The loop heat pipe according to claim 2, wherein the elastic member is a cross-sectionally U-shaped thin plate member. The loop heat pipe according to claim 2, wherein the elastic member is a bellows. The loop heat pipe according to any one of claims 1 to 4, wherein the support member is a connecting pipe provided so as to partition the liquid storage space and the vapor flow path. The expandable member is provided in the connection pipe so as to partition the liquid reservoir space and the vapor channel, and the working fluid in the liquid reservoir space and the working fluid in the vapor channel The loop type heat pipe according to claim 5, wherein the loop type heat pipe is doubled so as to form a heat insulating space that suppresses heat transfer therebetween. The loop heat pipe according to claim 6, wherein a heat insulator is sealed in the heat insulation space. The loop heat pipe according to claim 6, wherein the working fluid vaporized from the vapor channel enters the heat insulation space, and the working fluid is liquefied and held in the heat insulation space. The loop heat pipe according to claim 1, wherein the thermal expansion difference absorbing portion is a thin wall portion provided in either the evaporator container or the support member. The thermal expansion difference absorbing portion is provided between the small cylindrical portion of the support member, the large cylindrical portion of the support member that overlaps the small cylindrical portion, and the small cylindrical portion and the large cylindrical portion. The loop heat pipe according to claim 1, further comprising a sealing member that is movably sealed.   The loop heat pipe according to claim 1, wherein the thermal expansion difference absorbing portion is a portion of the support member that extends at right angles to the evaporator container and the wick.

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