JP2008281275A - Loop heat pipe, cooling apparatus, electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loop heat pipe capable of efficiently cooling a heating component regardless of the installation angle. <P>SOLUTION: The loop heat pipe 33 comprises an evaporation section 42, a condensation section 43, a steam pipe 44, a liquid return pipe 45, and a wick 46. The evaporation section 42 is formed by filling working fluid into an annular flow channel 41, and vaporizing the working fluid with heat of the heating component 25B. The condensation section 43 liquefies the vaporized working fluid. The steam pipe 44 connects the evaporation section 42 to the condensation section 43, and passes the vaporized working fluid. The liquid return pipe 45 is disposed independently of the steam pipe 44, connects the evaporation section 42 to the condensation section 43, and passes the liquefied working fluid. A wick 46 is disposed inside each of the evaporation section 42, the condensation section 43, and the liquid return pipe 45, and generates capillary force. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a loop heat pipe for cooling a heat generating component, a cooling device including the same, and an electronic apparatus.

  For example, the following is known as a heat transport device for cooling a heat-generating component. This heat transport device includes a substrate provided with a liquid-layer working fluid flow path and a gas-phase working fluid flow path, an evaporator that removes heat from a heat-generating component, and a gas-phase working fluid in a liquid phase. A condenser to be condensed, a wick member provided in the evaporator, a communication hole provided in the substrate so as to communicate with the flow path of the substrate and the wick member, and particles filled in the communication hole. ing. The granular material includes several types having different particle diameters. The communication hole is filled with granules so that the particle size becomes smaller as it approaches the evaporator.

In this conventional example, the conductance decreases as it approaches the evaporator due to the particles filled as described above. This describes that the movement of the working fluid is promoted to prevent the backflow of the working fluid (for example, see Patent Document 1).
JP 200477051 A

  In the invention described in Patent Document 1, since no treatment is made for the flow path of the working fluid in the liquid layer, when the installation angle of the heat transport device is inappropriate, the liquefied working fluid is discharged from the condenser. There is a risk that it will not return to the evaporator.

  An object of the present invention is to provide a loop heat pipe that can efficiently cool a heat-generating component regardless of the installation angle.

  In order to achieve the above object, a loop heat pipe according to an embodiment of the present invention is a loop heat pipe formed by enclosing a working fluid in an annular flow path, and is formed by heat of a heat-generating component. An evaporating part for evaporating the working fluid; a condensing part for liquefying the evaporating working fluid; a vapor pipe for connecting the evaporating part and the condensing part and passing the vaporized working fluid; and the vapor pipe And is connected to the evaporation unit and the condensing unit, and inside the liquid return pipe through which the liquefied working fluid is passed, the evaporation unit, the condensing unit, and the liquid return pipe And a wick for providing capillary force.

  In order to achieve the above object, a cooling device according to one aspect of the present invention includes a heat receiving part thermally connected to a heat generating component, a heat sink that releases heat of the heat receiving part to the outside, and the heat receiving part. A heat pipe thermally connected to the heat sink, and a loop heat pipe formed by enclosing a working fluid in an annular flow path, the loop heat pipe being heated by the heat of the heat-generating component. An evaporating part for evaporating the working fluid; a condensing part for liquefying the evaporating working fluid; a vapor pipe for connecting the evaporating part and the condensing part and passing the vaporized working fluid; and the vapor pipe And is connected to the evaporation unit and the condensing unit, and inside the liquid return pipe through which the liquefied working fluid is passed, the evaporation unit, the condensing unit, and the liquid return pipe Provided Together they are provided with a wick causing capillary force, the.

  In order to achieve the above object, an electronic device according to an aspect of the present invention includes a housing, a heat generating component housed in the housing, a heat generating component housed in the housing, and the heat generating component. A cooling device for cooling the electronic device, wherein the cooling device is a heat receiving part thermally connected to the heat generating component, a heat sink that releases heat of the heat receiving part to the outside, and the heat receiving part A loop heat pipe formed by enclosing a working fluid in an annular flow path and thermally connecting the heat sink and the heat sink, wherein the loop heat pipe is a heat of the heat-generating component. An evaporator that vaporizes the working fluid, a condenser that liquefies the vaporized working fluid, a vapor pipe that connects the evaporator and the condenser, and through which the vaporized working fluid passes, What is a steam pipe? And is provided in each of the liquid return pipe through which the liquefied working fluid is passed, the evaporator, the condenser, and the liquid return pipe. And a wick for generating capillary force.

  ADVANTAGE OF THE INVENTION According to this invention, the loop heat pipe which can cool a heat-emitting component efficiently irrespective of an installation angle can be provided.

  Below, with reference to FIGS. 1-6, 1st Embodiment of an electronic device is described. As shown in FIG. 1, a portable computer 11, which is an example of an electronic device, includes a main body unit 12, a display unit 13, and a hinge mechanism 14 provided between the main body unit 12 and the display unit 13. . The hinge mechanism 14 supports the display unit 13 so that it can rotate with respect to the main unit 12.

  The display unit 13 has a display 15. The display 15 is composed of a liquid crystal display, for example. As shown in FIGS. 1 and 2, the main unit 12 includes a housing 21, a keyboard 22 attached to the housing 21, a touch pad 23, buttons 24, and a printed circuit board housed inside the housing 21. 25, and a cooling device 26 for cooling the heat generating component 25B of the printed circuit board 25.

  As shown in FIGS. 2 and 3, the printed circuit board 25 includes a printed wiring board 25 </ b> A in which a plurality of copper wiring layers are stacked, and a heat generating component 25 </ b> B mounted on the printed circuit board 25. . The heat generating component 25B is configured by, for example, a CPU (central processing unit), but is not limited thereto. The heat generating component 25B may be another circuit component such as a north bridge or a graphics chip. In the present embodiment, only one heat generating component 25B cooled by the cooling device 26 is shown. However, the present invention is not limited to this, and a plurality of heat generating components are cooled by the cooling device of the present embodiment. It may be.

  The cooling device 26 is accommodated in the housing 21. The cooling device 26 includes a heat receiving portion 31 thermally connected to the heat generating component 25B, a heat sink 32 that releases heat of the heat receiving portion 31 to the outside, and a loop heat pipe that thermally connects the heat receiving portion 31 and the heat sink 32. 33 and a fan unit 34 for promoting heat dissipation in the heat sink 32. In this embodiment, the heat receiving part 31 is comprised by a part of loop heat pipe 33, for example. But the heat receiving part 31 is not limited to this, For example, thermal conductivity is favorable, for example, you may provide the rectangular heat receiving plate as a heat receiving part. The heat sink 32 is formed by connecting a plurality of rectangular fins.

  As shown in FIG. 3, the fan unit 34 includes a fan main body 34A, a casing 34B surrounding the fan main body 34A, and a motor for rotating the fan main body 34A. The motor is electrically connected to the printed circuit board 25, and the fan main body 34A can be rotated by the control of the printed circuit board 25.

  As shown in FIG. 4, the loop heat pipe 33 is formed by overlapping a first plate member 33A and a second plate member 33B. The first plate member 33A and the second plate member 33B are each formed of copper. The material of the first plate member 33A and the second plate member 33B is not limited to this. The first plate member 33A and the second plate member 33B may be formed of an aluminum alloy.

  A groove 35 is formed in the second plate member 33B. These grooves 35 form an annular flow path 41 in which a working fluid is enclosed. The groove 35 is formed by, for example, an etching process. For example, three flow paths 41 are formed in the loop heat pipe 33.

  The working fluid can change state between liquid and gas. The working fluid is composed of water, for example. However, the working fluid is not limited to water. The working fluid may be, for example, ethanol, ammonia, or butane.

  In addition, the heat transport amount of the loop heat pipe 33 is remarkably improved as compared with the heat transport amount of the conventional rod-shaped heat pipe, and cannot be discussed in the same row as the conventional heat pipe. More specifically, the heat transport amount of the conventional rod-shaped heat pipe (outer diameter 6 mm) is, for example, about 35 W, whereas the heat transport amount of the loop heat pipe (outer diameter 4.2 mm) is For example, it is about 1000W.

  Subsequently, each flow path 41 will be described in detail with reference to FIGS. 5 and 6. FIG. 5 schematically shows the structure of the flow path 41. The flow path 41 includes an evaporator 42 that vaporizes the working fluid by the heat of the heat generating component 25 </ b> B, a condenser 43 that liquefies the working fluid vaporized by the evaporator 42, and a steam pipe that connects the evaporator 42 and the condenser 43. 44 and the vapor pipe 44 are provided independently, and a liquid return pipe 45 that connects the evaporation section 42 and the condensation section 43, and a wick provided inside the evaporation section 42, the condensation section 43, and the liquid return pipe 45, respectively. 46.

  The evaporator 42 is thermally connected to the heat generating component 25B. In the evaporating section 42, the working fluid can be vaporized to remove heat from the heat generating component 25B. The condensing unit 43 is thermally connected to the heat sink 32. In the condensing part 43, the working fluid can be liquefied and the heat transmitted from the heat generating component 25B can be transmitted to the heat sink 32. The working fluid vaporized by the evaporator 42 is passed through the steam pipe 44. The working fluid liquefied by the condenser 43 is passed through the liquid return pipe 45.

  The wick 46 is a general term for what causes a capillary force to act on the liquefied working fluid to return the working fluid to the evaporation section 42. In the present embodiment, the wick 46 is formed of, for example, a porous material 49 formed by sintering metal powder inside the flow channel 41 as shown in FIG. In FIG. 4, the wick 46 is not shown.

  The wick 46 has a first portion 47 that is densely arranged and a second portion 48 that is sparsely arranged. The first portion 47 of the wick 46 is disposed inside the evaporation unit 42. The second portion 48 of the wick 46 is disposed across the inside of the evaporation unit 42, the inside of the liquid return pipe 45, and the inside of the condensing unit 43. The wick 46 is formed continuously from the condensing unit 43 to the evaporation unit 42 via the liquid return pipe 45. The second portion 48 of the wick 46 may not be provided inside the evaporation unit 42 but may be disposed only inside the liquid return pipe 45 and inside the condensing unit 43.

  The second portion 48 of the wick 46 further includes first to third regions 48A, 48B, and 48C having different densities. More specifically, the second portion 48 of the wick 46 includes a first region 48A that is the densest of these, a third region 48C that is the least sparse among these, and a A second region 48B having an intermediate density. The first region 48 </ b> A and the second region 48 </ b> B are disposed inside the liquid return pipe 45. The third region 48 </ b> C is disposed across the liquid return pipe 45 and the condensing unit 43.

  In the cooling device of the present embodiment, the heat of the heat generating component 25 </ b> B is transmitted to the evaporation unit 42 of the loop heat pipe 33 through the heat receiving unit 31. In the evaporation section 42, the working fluid that has absorbed the heat is vaporized and sent to the condensing section 43 through the vapor pipe 44. In the condensing unit 43, the working fluid releases the heat and liquefies. Thus, the heat of the heat generating component 25B is transmitted to the heat sink 32. The heat transmitted to the heat sink 32 is transmitted to the air sent from the fan unit 34 and released into the atmosphere through the opening 27 of the housing 21.

  In the condensing part 43, a third region 48C of the second part 48 of the wick 46 that is continuous with the evaporation part 42 is arranged. At this time, the working fluid is volatilized on the end surface of the first portion 47 of the wick 46 of the evaporation section 42. For this reason, a capillary force acts on the third region 48C of the second portion 48 of the wick 46, and the working fluid liquefied in the condensing unit 43 reaches the evaporation unit 42 without stagnation in the condensing unit 43. Sent. In the route from the condensing unit 43 to the evaporation unit 42 via the liquid return pipe 45, the density of the wicks 46 increases as going to the evaporation unit 42, and as a result, the pressure loss gradually increases. For this reason, it is possible to prevent the working fluid from flowing backward from the evaporation section 42 toward the liquid return pipe 45 as much as possible.

  The above is the embodiment of the portable computer 11 which is an example of the electronic apparatus. According to the present embodiment, the loop heat pipe 33 is formed by enclosing the working fluid in the annular flow path 41, and evaporating the working fluid by the heat of the heat generating component 25B, and the vaporized operation. The condensing unit 43 for liquefying the fluid, the evaporating unit 42 and the condensing unit 43 are connected to each other, and the vapor pipe 44 through which the vaporized working fluid is passed and the vapor pipe 44 are provided independently. The wick 46 is connected to the unit 43 and provided inside the liquid return pipe 45 through which the liquefied working fluid is passed, the evaporation unit 42, the condensing unit 43, and the liquid return pipe 45, and generates capillary force. And.

  According to this configuration, the wick 46 that generates a capillary force is provided in each of the evaporator 42, the condenser 43, and the liquid return pipe 45, so that the working medium liquefied in the condenser 43 is wick 46 in the condenser 43. Can be efficiently guided to the evaporation unit 42. Thereby, generation | occurrence | production of the top heat which the circulation of a working fluid stops can be prevented, and the heat-emitting component 25B can be cooled efficiently irrespective of the installation angle of the loop heat pipe 33.

  In this case, the wick 46 is continuously formed so as to reach the evaporator 42 from the condenser 43 via the liquid return pipe 45. For example, when the wick 46 is disposed in the evaporation unit 42, the temperature of the wick 46 increases with the evaporation unit 42 due to the use of the portable computer 11. At this time, since the vaporization of the working fluid occurs at both ends of the wick 46, there is a possibility that a backflow of the working fluid may occur. In the present embodiment, the wick 46 is continuously formed so as to reach the evaporator 42 from the condenser 43, and one end of the wick 46 is disposed in the condenser 43. Since the temperature of the condensing unit 43 is lower than the temperature of the evaporating unit 42, the working fluid is suppressed from evaporating from the end of the wick 46 in the condensing unit 43. Thereby, it is possible to prevent a back flow from occurring in the working fluid.

  In this case, the wick 46 has a first portion 47 arranged densely and a second portion 48 arranged sparsely, and the first portion 47 is arranged inside the evaporation unit 42. In addition, the second portion 48 is disposed inside the condensing unit 43 and the liquid return pipe 45. As the density of the wick 46 increases, the pressure loss applied to the working fluid increases in proportion to this. On the contrary, when the density of the wick 46 is reduced, the pressure loss applied to the working fluid is reduced in proportion thereto. As described above, when the wicks 46 are continuously arranged at a uniform density from the condenser 43 to the evaporator 42, the pressure loss of the liquid return pipe 45 increases. According to this configuration, since the pressure loss can be reduced as the second portion 48 as a whole, an increase in the pressure loss in the flow path 41 can be prevented.

  In this case, the density of the second portion 48 of the wick 46 increases as it approaches the evaporation section 42. For example, when the density of the wicks 46 is uniformly reduced in the second portion 48, the pressure loss is reduced and the backflow of the working fluid is likely to occur. According to the present embodiment, since the pressure loss can be gradually increased as approaching the evaporation unit 42, it is possible to prevent the backflow of the working fluid while suppressing an increase in the pressure loss as much as possible.

  In this case, the wick 46 is composed of a porous material 49 disposed in the flow path 41. According to this configuration, the density difference of the wick 46 can be easily formed by changing the amount and particle size of the metal powder to be sintered.

  Next, a second embodiment of the electronic device will be described with reference to FIGS. A portable computer 61, which is an example of the electronic apparatus of the second embodiment, is different from the first embodiment in the structure of the wick 62, but the other parts are common. For this reason, a different part from 1st Embodiment is mainly demonstrated, a common code | symbol is attached | subjected about a common location, and description is abbreviate | omitted.

  The appearance of the portable computer 61 according to the second embodiment is the same as that shown in FIG.

  The portable computer 61 includes a main unit 12, a display unit 13, and a hinge mechanism 14, and the main unit 12 includes a housing 21, a printed circuit board 25 accommodated in the housing 21, and a print. And a cooling device 26 for cooling the heat generating component 25B of the circuit board 25.

  The cooling device 26 includes a heat receiving portion 31 thermally connected to the heat generating component 25B, a heat sink 32 that releases heat of the heat receiving portion 31 to the outside, and a loop heat pipe that thermally connects the heat receiving portion 31 and the heat sink 32. 63 and a fan unit 34 for promoting heat dissipation in the heat sink 32. In the present embodiment, the heat receiving portion 31 is configured by a part of the loop heat pipe 63, for example.

  The loop heat pipe 63 has, for example, three flow paths 41. The working fluid sealed in each flow path 41 is composed of water whose state can be changed between a liquid and a gas. The overall configuration of each channel 41 is the same as that shown in FIG. That is, the flow path 41 includes an evaporation section 42, a condensation section 43, a steam pipe 44, a liquid return pipe 45, and a wick 62. The wick 62 is provided in each of the evaporator 42, the condenser 43, and the liquid return pipe 45.

  As shown in FIGS. 7 and 8, in the present embodiment, the wick 62 includes, for example, a plurality of groove portions 64 formed in the flow path 41. In the present embodiment, a capillary force is generated by the groove 64. The plurality of groove portions 64 are formed by, for example, pressing, etching, cutting, or the like.

  The wick 62 has a first portion 65 in which the groove portions 64 are densely arranged, and a second portion 66 in which the groove portions 64 are sparsely arranged. The first portion 65 of the wick 62 is disposed inside the evaporation unit 42. The second portion 66 of the wick 62 extends over the inside of the evaporation unit 42, the inside of the liquid return pipe 45, and the inside of the condensing unit 43. The wick 62 is continuously formed so as to reach the evaporator 42 from the condenser 43 via the liquid return pipe 45. Note that the second portion 66 of the wick 62 may not be provided inside the evaporation unit 42 but may be disposed only inside the liquid return pipe 45 and inside the condensing unit 43.

  The second portion 66 of the wick 62 further includes first to third regions 66A, 66B, and 66C in which the groove portions 64 have different densities. More specifically, the second portion 66 of the wick 62 includes a first region 66A in which the density of the groove portion 64 is the densest among these, and a first region 66A in which the groove portion 64 is the most sparse. 3 regions 66C and a second region 66B having a density of the intermediate groove portion 64. The first region 66A and the second region 66B are arranged inside the liquid return pipe 45. The second region 66 </ b> B is disposed across the liquid return pipe 45 and the condensing unit 43.

  In the cooling device of this embodiment, the heat of the heat generating component 25B is transmitted to the loop heat pipe 63 via the heat receiving portion 31, and the heat is transmitted to the heat sink 32 and released into the atmosphere. In the condensing unit 43, a second region 66 </ b> B of the second portion 66 of the wick 62 that is continuous with the evaporation unit 42 is disposed. At this time, the working fluid is volatilized on the end face of the first portion 65 of the wick 62 of the evaporation section 42. For this reason, a capillary force acts on the third region 66C of the second portion 66 of the wick 62, and the working fluid liquefied in the condensing unit 43 reaches the evaporation unit 42 without stagnation in the condensing unit 43. Sent.

  According to the present embodiment, the wick 62 includes a plurality of groove portions 64 formed in the flow channel 41. According to this configuration, the gradient of the density of the wicks 62 can be easily provided only by changing the number of the groove portions 64.

  Subsequently, a third embodiment of the electronic device will be described with reference to FIGS. 9 and 10. A portable computer 71, which is an example of the electronic apparatus of the third embodiment, is different from the first embodiment in the structure of the wick 72, but the other parts are common. For this reason, a different part from 1st Embodiment is mainly demonstrated, a common code | symbol is attached | subjected about a common location, and description is abbreviate | omitted.

  The appearance of the portable computer 71 according to the third embodiment is the same as that shown in FIG. The portable computer 71 includes a main unit 12, a display unit 13, and a hinge mechanism 14, and the main unit 12 includes a casing 21, a printed circuit board 25 accommodated in the casing 21, And a cooling device 26 for cooling the heat generating component 25B of the printed circuit board 25.

  The cooling device 26 includes a heat receiving portion 31 thermally connected to the heat generating component 25B, a heat sink 32 that releases heat of the heat receiving portion 31 to the outside, and a loop heat pipe that thermally connects the heat receiving portion 31 and the heat sink 32. 73 and a fan unit 34 for promoting heat dissipation in the heat sink 32. In the present embodiment, the heat receiving part 31 is configured by a part of the loop heat pipe 73, for example.

  The loop heat pipe 73 has, for example, three flow paths 41. The working fluid sealed in each flow path 41 is composed of water whose state can be changed between a liquid and a gas. The overall configuration of each channel 41 is the same as that shown in FIG. That is, the flow path 41 includes an evaporation section 42, a condensation section 43, a steam pipe 44, a liquid return pipe 45, and a wick 72. The wick 72 is provided in each of the evaporator 42, the condenser 43, and the liquid return pipe 45.

  In the present embodiment, the wick 72 is configured by, for example, a mesh 74 disposed in the flow path 41. That is, in this embodiment, the capillary force is generated by the mesh 74. In addition, you may arrange | position the wire for supporting the circumference | surroundings of the mesh 74 in the flow path 41. FIG.

  The wick 72 has a first portion 76 in which the mesh 74 has a fine mesh, and a second portion 77 in which the mesh 74 has a coarse mesh. The first portion 76 of the wick 72 is disposed inside the evaporation unit 42. The second portion 77 of the wick 72 extends over the inside of the evaporation unit 42, the inside of the liquid return pipe 45, and the inside of the condensing unit 43. The wick 72 is continuously formed so as to reach the evaporator 42 from the condenser 43 via the liquid return pipe 45. The second portion 77 of the wick 72 may not be provided inside the evaporation unit 42 but may be disposed only inside the liquid return pipe 45 and inside the condensing unit 43.

  The second portion 77 of the wick 72 further includes first to third regions 77A, 77B, and 77C having different mesh roughness of the mesh 74. More specifically, the second portion 77 of the wick 72 includes a first region 77A having the finest mesh among them and a third region 77A having the coarsest mesh among them. A region 77C and a second region 77B having an intermediate mesh eye are included. The first region 77A and the second region 77B are arranged inside the liquid return pipe 45. The third region 77C is disposed across the liquid return pipe 45 and the condensing unit 43. The wick 72 is continuously formed so as to reach the evaporator 42 from the condenser 43 via the liquid return pipe 45. The second portion 77 of the wick 72 may not be provided inside the evaporation unit 42 but may be disposed only inside the liquid return pipe 45 and inside the condensing unit 43.

  In the cooling device 26 of this embodiment, the heat of the heat generating component 25B is transmitted to the loop heat pipe 73 via the heat receiving portion 31, and the heat is transmitted to the heat sink 32 and released into the atmosphere.

  In the condensing part 43, a third region 77C of the second part 77 of the wick 72 that is continuous with the evaporation part 42 is disposed. At this time, the working fluid is volatilized on the end face of the first portion 76 of the wick 72 of the evaporation section 42. For this reason, a capillary force acts on the third region 77C of the second portion 77 of the wick 72, and the working fluid liquefied in the condensing unit 43 reaches the evaporation unit 42 without stagnation in the condensing unit 43. Sent.

  According to the present embodiment, the wick 72 is configured with a mesh 74 disposed in the flow path 41. According to this configuration, it is possible to easily provide a gradient in the density of the wick 72 simply by preparing a plurality of types of meshes 74 having different eye roughnesses.

  Next, a fourth embodiment of the electronic device will be described with reference to FIG. 11 and FIG. The portable computer 81, which is an example of the electronic device of the fourth embodiment, is different from the first embodiment in the structure of the wick 82, but the other parts are common. For this reason, a different part from 1st Embodiment is mainly demonstrated, a common code | symbol is attached | subjected about a common location, and description is abbreviate | omitted.

  The appearance of the portable computer 81 according to the fourth embodiment is the same as that shown in FIG. The portable computer 81 includes a main unit 12, a display unit 13, and a hinge mechanism 14. The main unit 12 includes a housing 21, a printed circuit board 25 accommodated in the housing 21, and a print. And a cooling device 26 for cooling the heat generating component 25B of the circuit board 25.

  The cooling device 26 includes a heat receiving portion 31 thermally connected to the heat generating component 25B, a heat sink 32 that releases heat of the heat receiving portion 31 to the outside, and a loop heat pipe that thermally connects the heat receiving portion 31 and the heat sink 32. 83 and a fan unit 34 for promoting heat dissipation in the heat sink 32. In the present embodiment, the heat receiving unit 31 is configured by a part of the loop heat pipe 83, for example.

  The loop heat pipe 83 has, for example, three flow paths 41. The working fluid sealed in each flow path 41 is composed of water whose state can be changed between a liquid and a gas. The overall configuration of each channel 41 is the same as that shown in FIG. That is, the flow path 41 includes an evaporation section 42, a condensation section 43, a steam pipe 44, a liquid return pipe 45, and a wick 82. The wick 82 is provided in each of the evaporator 42, the condenser 43, and the liquid return pipe 45.

  In the present embodiment, the wick 82 includes, for example, a plurality of wires 84 arranged in the flow path 41. That is, in the present embodiment, the capillary force is generated by the gap formed between the wires 84.

  The wick 82 has a first portion 85 in which the wires 84 are densely arranged and a second portion 86 in which the wires 84 are sparsely arranged. The first portion 85 of the wick 82 is disposed inside the evaporation unit 42. The second portion 86 of the wick 82 extends over the inside of the evaporation unit 42, the inside of the liquid return pipe 45, and the inside of the condensing unit 43. The wick 82 is continuously formed so as to reach the evaporator 42 from the condenser 43 via the liquid return pipe 45. The second portion 86 of the wick 82 may not be provided inside the evaporation unit 42 but may be disposed only inside the liquid return pipe 45 and inside the condensing unit 43.

  The second portion 86 of the wick 82 further includes first to third regions 86A, 86B, 86C having different numbers of wires 84 disposed therein. More specifically, the second portion 86 of the wick 82 includes a first region 86A in which the wires 84 are most densely arranged, and a wire 84 in which the wires 84 are most sparsely arranged. A third region 86C, and a second region 86B in which the intermediate number of wires 84 are disposed. The first region 86A and the second region 86B are disposed inside the liquid return pipe 45. The third region 86 </ b> C is disposed across the liquid return pipe 45 and the condensing unit 43.

  In the cooling device 26 of the present embodiment, the heat of the heat generating component 25B is transmitted to the loop heat pipe 83 via the heat receiving portion 31, and the heat is transmitted to the heat sink 32 and released into the atmosphere. In the condensing part 43, a third region 86C of the second part 86 of the wick 82 that is continuous with the evaporation part 42 is disposed. At this time, the working fluid is volatilized on the end face of the first portion 85 of the wick 82 of the evaporation section 42. For this reason, a capillary force acts on the third region 86C of the second portion 86 of the wick 82, and the working fluid liquefied in the condensing unit 43 reaches the evaporation unit 42 without stagnation in the condensing unit 43. Sent.

  According to the present embodiment, the wick 82 includes a plurality of wires 84 arranged in the flow path 41. According to this configuration, it is possible to easily provide a gradient in the density of the wick 82 simply by changing the number of the wires 84.

  Next, a fifth embodiment of the electronic device will be described with reference to FIG. A portable computer 91, which is an example of the electronic device of the fifth embodiment, is different from the first embodiment in the structure of the wick 92, but the other parts are common. For this reason, a different part from 1st Embodiment is mainly demonstrated, a common code | symbol is attached | subjected about a common location, and description is abbreviate | omitted.

  The appearance of the portable computer 91 according to the fifth embodiment is the same as that shown in FIG.

  The cooling device 26 includes a heat receiving portion 31 thermally connected to the heat generating component 25B, a heat sink 32 that releases heat of the heat receiving portion 31 to the outside, and a loop heat pipe that thermally connects the heat receiving portion 31 and the heat sink 32. 93 and a fan unit 34 for promoting heat dissipation in the heat sink 32. In the present embodiment, the heat receiving portion 31 is configured by a part of the loop heat pipe 93, for example.

  The loop heat pipe 93 has, for example, three flow paths 41. The working fluid sealed in each flow path 41 is composed of water whose state can be changed between a liquid and a gas. A cross-sectional view schematically showing each flow path 41 is shown in FIG. The flow path 41 includes an evaporation section 42, a condensation section 43, a steam pipe 44, a liquid return pipe 45, and a wick 92. The wick 92 is provided in each of the evaporator 42, the condenser 43, and the liquid return pipe 45.

  In the present embodiment, the wick 92 is formed of, for example, a porous material 49 formed by sintering metal powder inside the flow path 41.

  The wick 92 has a first portion 94 that is densely arranged and a second portion 95 that is sparsely arranged. The first portion 94 of the wick 92 is disposed inside the evaporation unit 42. The second portion 95 of the wick 92 extends over the inside of the evaporation unit 42, the inside of the liquid return pipe 45, and the inside of the condensing unit 43. The wick 92 is continuously formed from the condensing unit 43 to the evaporation unit 42 via the liquid return pipe 45. Further, unlike the first embodiment, the second portion 95 of the wick 92 is configured with a uniform density. The second portions 95 are uniformly arranged at a low density equivalent to the density of the third region 48C of the wick 48 of the first embodiment. Note that the second portion 95 of the wick 92 may not be provided inside the evaporation unit, but may be arranged only inside the liquid return pipe 45 and inside the condensing unit 43.

  In the cooling device 26, the heat of the heat generating component 25B is transmitted to the loop heat pipe 93 via the heat receiving portion 31, and the heat is transmitted to the heat sink 32 and released into the atmosphere. In the condensing unit 43, a second portion 95 of the wick 92 that is continuous with the evaporation unit 42 is disposed. At this time, the working fluid is volatilized on the end surface of the first portion 94 of the wick 92 of the evaporation section 42. For this reason, a capillary force acts on the second portion 95 of the wick 92, and the working fluid liquefied in the condensing unit 43 is sent to the evaporating unit 42 without stagnation in the condensing unit 43.

  According to the present embodiment, the second portion 95 of the wick 92 is uniformly arranged at a lower density than the first portion 94. For this reason, even if the wick 92 is provided in each of the evaporator 42, the condenser 43, and the liquid return pipe 45, it is possible to prevent the pressure loss from increasing in the flow path 41. Since one end of the wick 92 is disposed in the condensing unit 43, the temperature of the condensing unit 43 is lower than the temperature of the evaporating unit 42. For this reason, the evaporation amount of the working fluid is small from the end of the wick 92 in the condensing unit 43, and even if a backflow occurs in the working fluid, the amount is very small.

  The electronic apparatus of the present invention is not limited to the above portable computer, and can be implemented for other electronic apparatuses such as a portable information terminal. In addition, the electronic apparatus can be variously modified and implemented without departing from the gist of the invention.

1 is a perspective view showing a portable computer that is an example of an electronic apparatus according to a first embodiment. FIG. 2 is a cross-sectional view showing the casing of the portable computer shown in FIG. 1 cut in the horizontal direction. The perspective view which decomposes | disassembles and shows the cooling device accommodated in the inside of the housing | casing shown in FIG. The perspective view which decomposes | disassembles and shows the loop heat pipe of the cooling device shown in FIG. Sectional drawing which showed the inside of the loop heat pipe shown in FIG. 4 typically. Sectional drawing along the position of the F6-F6 line of the loop heat pipe shown in FIG. Sectional drawing which shows typically the loop heat pipe of the portable computer which is an example of the electronic device which concerns on 2nd Embodiment. Sectional drawing along the position of F8-F8 line of the loop heat pipe shown in FIG. Sectional drawing which shows typically the loop heat pipe of the portable computer which is an example of the electronic device which concerns on 3rd Embodiment. Sectional drawing along the position of F10-F10 line of the loop heat pipe shown in FIG. Sectional drawing which shows typically the loop heat pipe of the portable computer which is an example of the electronic device which concerns on 4th Embodiment. Sectional drawing along the position of F12-F12 line of the loop heat pipe shown in FIG. Sectional drawing which shows typically the loop heat pipe of the portable computer which is an example of the electronic device which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 61, 71, 81, 91 ... Portable computer, 21 ... Housing, 25B ... Heat generating component, 26 ... Cooling device, 31 ... Heat receiving part, 32 ... Heat sink, 33, 63, 73, 93 ... Loop heat pipe, 41 ... Flow path, 42 ... Evaporation part, 43 ... Condensation part, 44 ... Steam pipe, 45 ... Liquid return pipe, 46, 62, 72, 92 ... Wick, 47, 65, 76, 85, 94 ... First part, 48, 66, 77, 86, 95 ... second part, 49 ... porous material, 64 ... groove, 74 ... mesh, 82 ... wick, 83 ... loop heat pipe, 84 ... wire

Claims (10)

A loop heat pipe formed by enclosing a working fluid in an annular flow path,
An evaporating section for vaporizing the working fluid by heat of a heat generating component;
A condensing part for liquefying the vaporized working fluid;
While connecting the evaporation unit and the condensing unit, a vapor pipe through which the vaporized working fluid is passed,
A liquid return pipe that is provided independently of the steam pipe, connects the evaporation section and the condensation section, and allows the liquefied working fluid to pass through;
Wick that is provided inside the evaporation unit, the condensing unit, and the liquid return pipe, respectively, and generates a capillary force;
A loop heat pipe comprising:   2. The loop heat pipe according to claim 1, wherein the wick is continuously formed from the condensing unit to the evaporation unit via the liquid return pipe. The wick has a first portion arranged densely and a second portion arranged sparsely,
The first portion is disposed inside the evaporation unit,
The loop heat pipe according to claim 2, wherein the second portion is disposed inside the condensing unit and the liquid return pipe.   The loop heat pipe according to claim 3, wherein the second portion of the wick has a higher density as it approaches the evaporation portion.   The loop heat pipe according to claim 4, wherein the wick is made of a porous material disposed in the flow path.   The loop heat pipe according to claim 4, wherein the wick includes a plurality of grooves formed in the flow path.   The loop heat pipe according to claim 4, wherein the wick is configured by a mesh arranged in the flow path.   5. The loop heat pipe according to claim 4, wherein the wick includes a plurality of wires disposed in the flow path. A heat receiving part thermally connected to the heat generating component;
A heat sink that releases the heat of the heat receiving portion to the outside;
A loop heat pipe formed by sealing the heat receiving portion and the heat sink and enclosing a working fluid in an annular flow path,
Comprising
The loop heat pipe is
An evaporation unit that vaporizes the working fluid by heat of the heat-generating component;
A condensing part for liquefying the vaporized working fluid;
While connecting the evaporation unit and the condensing unit, a vapor pipe through which the vaporized working fluid is passed,
A liquid return pipe that is provided independently of the steam pipe, connects the evaporation section and the condensation section, and allows the liquefied working fluid to pass through;
Wick that is provided inside the evaporation unit, the condensing unit, and the liquid return pipe, respectively, and generates a capillary force;
A cooling device comprising: A housing,
A heat generating component housed in the housing;
A cooling device that is housed in the housing and cools the heat-generating component;
An electronic device comprising:
The cooling device is
A heat receiving portion thermally connected to the heat generating component;
A heat sink that releases the heat of the heat receiving portion to the outside;
A loop heat pipe formed by sealing the heat receiving portion and the heat sink and enclosing a working fluid in an annular flow path,
With
The loop heat pipe is
An evaporation unit that vaporizes the working fluid by heat of the heat-generating component;
A condensing part for liquefying the vaporized working fluid;
While connecting the evaporation unit and the condensing unit, a vapor pipe through which the vaporized working fluid is passed,
A liquid return pipe that is provided independently of the steam pipe, connects the evaporation section and the condensation section, and allows the liquefied working fluid to pass through;
Wick that is provided inside the evaporation unit, the condensing unit, and the liquid return pipe, respectively, and generates a capillary force;
An electronic device comprising:

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