JP2015183880A - Loop type heat pipe, its process of manufacture, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a loop type heat pipe of which thin-type unit can be attained without producing any reduction in heat transmittance performance caused by a reverse flow of work fluid, and provide its process of manufacture and an electronic apparatus.SOLUTION: This invention relates to a loop type heat pipe comprising an evaporator 23 for vaporizing work fluid C; a condenser 24 for liquefying the work fluid C; a liquid pipe 26 connecting the evaporator 23 with the condenser 24 and having a lower surface 35x and an upper surface 37x therein; a plurality of columns 38 arranged in at least one of the lower surface 35x and the upper surface 37x; a porous member 40 arranged in the liquid pipe 26 and supported by the plurality of columns 38; and a steam pipe 25 connecting the evaporator 23 with the condenser 24 to form a loop together with the liquid pipe 26.

Description

  The present invention relates to a loop heat pipe, a manufacturing method thereof, and an electronic apparatus.

  With the advent of an advanced information society, mobile electronic devices such as smartphones and tablet terminals are spreading. Since mobile electronic devices are thinned so that they can be easily carried, it is difficult to provide a blower fan for cooling heat-generating components such as a CPU (Central Processing Unit).

  As a method for cooling the heat generating component, for example, there is a method of transporting the heat of the heat generating component to the outside with a metal plate or a heat diffusion sheet having good thermal conductivity. However, in this method, the heat that can be transported is limited by the thermal conductivity of the metal plate or the thermal diffusion sheet. For example, the thermal conductivity of a graphite sheet used as a thermal diffusion sheet is about 500 W / mK to 1500 W / mK. With this thermal conductivity, the heat generating component is cooled when the heat generation amount of the heat generating component increases. It becomes difficult.

  Therefore, a heat pipe has been studied as a device that actively cools heat-generating components.

  The heat pipe is a device for transporting heat by utilizing the phase change of the working fluid, and has a higher thermal conductivity than that of the heat diffusion sheet. For example, a heat pipe having a diameter of 3 mm shows a large thermal conductivity of about 1500 W / mK to 2500 W / mK.

  There are several types of heat pipes. The loop heat pipe includes an evaporator that vaporizes the working fluid by the heat of the heat generating component, and a condenser that cools and vaporizes the vaporized working fluid. The evaporator and the condenser are connected by a liquid pipe and a vapor pipe that form a loop-shaped flow path, and the working fluid flows through the path in one direction.

  In this way, the direction of flow of the working fluid in the loop type heat pipe is one direction. Therefore, the resistance that the working fluid receives less compared to the heat pipe in which the liquid-phase working fluid and its vapor reciprocate in the pipe, and efficiently. Heat transport can be performed.

JP 2010-7905 A JP 2010-19495 A JP 2006-308263 A

  However, when a loop heat pipe is mounted on a thin electronic device such as a smartphone, the diameters of the liquid tube and the vapor tube must be reduced in accordance with the thickness of the electronic device. As a result, it is difficult for the working fluid to flow through the liquid pipe and the steam pipe, and the heat transport performance of the loop heat pipe may be deteriorated.

  The disclosed technology has been made in view of the above, and provides a loop-type heat pipe that can be reduced in thickness without causing a decrease in heat transport performance due to a backflow of a working fluid, a manufacturing method thereof, and an electronic device The purpose is to do.

  According to one aspect of the disclosure below, an evaporator that vaporizes a working fluid, a condenser that liquefies the working fluid, the evaporator and the condenser are connected, and a lower surface and an upper surface are inward. A liquid tube provided; a plurality of columns provided on at least one of the lower surface and the upper surface; a porous body provided in the liquid tube and supported by the plurality of columns; the evaporator and the condenser A loop type heat pipe having a steam pipe connected to a vessel and forming a loop with the liquid pipe is provided.

  According to another aspect of the disclosure, the heating component includes a heat generating component and a loop heat pipe that cools the heat generating component, and the loop heat pipe vaporizes the working fluid, and the working fluid. A condenser for liquefying, a liquid pipe connecting the evaporator and the condenser and having a lower surface and an upper surface inside, and a plurality of columns provided on at least one of the lower surface and the upper surface; An electronic apparatus comprising: a porous body provided in the liquid pipe and supported by the plurality of pillars; and a vapor pipe that connects the evaporator and the condenser and forms a loop with the liquid pipe Is provided.

  Further, according to another aspect of the disclosure, at least one of an upper surface and a lower surface inside a liquid pipe connected to each of an evaporator and a condenser connected to each other by a vapor pipe and forming a loop together with the vapor pipe A method for manufacturing a loop heat pipe is provided, which includes a step of forming a column in the liquid tube, a step of providing a porous body supported by the column in the liquid tube, and a step of injecting a working fluid into the liquid tube. .

  According to the following disclosure, by providing a porous body and a plurality of pillars supporting the porous body in a liquid pipe of a loop heat pipe, a capillary force that acts on the working fluid from the porous body as the working fluid flows back through the liquid pipe is disclosed. It is possible to secure a flow path for the working fluid to flow between the pillars while preventing.

  As a result, the flow of the working fluid in the liquid pipe becomes smooth, and the heat transport efficiency of the loop heat pipe can be improved.

FIG. 1 is a schematic diagram of a loop heat pipe used for the study. FIG. 2 is an enlarged plan view of the evaporator of the loop heat pipe used for the study and the vicinity thereof. FIG. 3 is a schematic plan view of the electronic apparatus according to the present embodiment. FIG. 3 is a cross-sectional view of the evaporator of the loop heat pipe according to the present embodiment and its surroundings. FIG. 5 is a cross-sectional view taken along the line II of FIG. 6 is a cross-sectional view taken along the line II-II in FIG. FIG. 7A is an enlarged plan view of the first outer layer sheet in the evaporator according to the present embodiment, and FIG. 7B is an enlarged plan view of the second outer layer sheet in the evaporator. FIG. 8 is an enlarged plan view of an inner layer sheet in the evaporator according to the present embodiment. FIG. 9 is an overall plan view of the inner layer sheet according to the present embodiment. FIG. 10 is a cross-sectional view of the steam pipe according to the present embodiment. FIG. 11 is an enlarged plan view of a portion corresponding to a porous body in each of the inner layer sheets from the first layer to the fourth layer according to the present embodiment. FIG. 12 is a plan view schematically showing the positions of the holes when the inner layer sheets according to the present embodiment are laminated. FIG. 13 is a plan view showing another example of the hole size according to the present embodiment. FIG. 14A is a schematic plan view showing an example of the size of holes in the evaporator according to the present embodiment, and FIG. 14B is an example of the size of holes in the liquid pipe according to the present embodiment. It is a schematic plan view which shows. FIG. 15A is a cross-sectional view of a liquid pipe of a loop heat pipe according to a comparative example, and FIG. 15B is a cross-sectional view of a liquid pipe according to the comparative example when the cross-sectional area of the flow path is increased. It is. FIG. 16 is a cross-sectional view of the liquid pipe when the width is widened in the present embodiment. FIG. 17 is a plan view (part 1) in the middle of manufacturing the loop heat pipe according to the present embodiment. FIG. 18 is a cross-sectional view (No. 1) in the middle of manufacturing the loop heat pipe according to the present embodiment. FIG. 19 is a plan view (part 2) in the middle of manufacturing the loop heat pipe according to the present embodiment. FIG. 20 is a cross-sectional view (part 2) of the loop-type heat pipe according to the present embodiment during manufacture. FIG. 21 is a plan view illustrating an example of a planar shape of a pillar included in the loop heat pipe according to the present embodiment. FIG. 22 is a cross-sectional view drawn based on an SEM (Scanning Electron Microscope) image of a portion corresponding to a porous body in the loop heat pipe according to the present embodiment.

  Prior to the description of the present embodiment, considerations made by the present inventor will be described.

  FIG. 1 is a schematic diagram of a loop heat pipe used for the study.

  The loop heat pipe 1 is accommodated in a mobile electronic device 2 such as a smartphone, and includes an evaporator 3 and a condenser 4.

  A vapor pipe 5 and a liquid pipe 6 are connected to the evaporator 3 and the condenser 4, and a loop-like flow path through which the working fluid C flows is formed by these pipes 5 and 6. Further, a heat generating component 7 such as a CPU is in thermal contact with the evaporator 3, and a vapor Cv of the working fluid C is generated by the heat of the heat generating component 7. The steam Cv is led to the condenser 4 through the steam pipe 5 and is liquefied in the condenser 4. Thereby, the heat generated in the heat generating component 7 moves to the condenser 4.

  FIG. 2 is an enlarged plan view of the evaporator 3 and the vicinity thereof.

  As shown in FIG. 2, a wick 10 is accommodated inside the evaporator 3. The material used for the wick 10 is generally a porous sintered metal or sintered ceramic, and it is ideal that the liquid-phase working fluid permeates the wick 10 near the liquid pipe 6.

  If such a state continues, a capillary force acts on the liquid-phase working fluid C from the wick 10, and the capillary force counters the vapor Cv of the working fluid C. It functions as a check valve that prevents back flow from the steam pipe 5 to the liquid pipe 6.

  However, according to the investigation by the inventor of the present application, it has been clarified that when the loop type heat pipe 1 is thinned, the steam Cv flows backward in the evaporator 3.

  This is because the pressure loss of the steam pipe 5 increases due to the reduction in thickness, so that the flow of the steam Cv in the steam pipe 5 is stagnated, and the working fluid C in the liquid phase in the condenser 4 (see FIG. 1) is caused by the steam Cv. This is probably because the liquid tube 6 cannot be pushed out.

  Further, it is considered that a part of the working fluid C is vaporized in the liquid pipe 6 due to heat transfer from the heat generating component 7 to the liquid pipe 6, and this also causes the backflow of the vapor Cv as described above. The phenomenon in which the liquid tube 6 is heated by the heat generating component 7 in this way is also called heat leak.

  When the steam Cv flows backward as described above, the heat transport performance of the loop heat pipe is remarkably deteriorated, and it becomes difficult to cool the heat generating component 7.

  Hereinafter, a description will be given of this embodiment that can prevent the backflow of the working fluid even if the thickness is reduced.

(This embodiment)
FIG. 3 is a schematic plan view of the electronic apparatus according to the present embodiment.

  The electronic device 20 is a mobile electronic device such as a smartphone or a tablet terminal, and includes a housing 21 and a loop heat pipe 22 accommodated therein.

  The loop heat pipe 22 includes an evaporator 23 that generates a vapor Cv of the working fluid C, and a condenser 24 that liquefies the working fluid C. A vapor pipe 25 and a liquid pipe 26 are connected to the evaporator 23 and the condenser 24, and a loop-like flow path through which the working fluid C flows is formed by these pipes 25 and 26.

  The liquid-phase working fluid C flows in one direction along the liquid pipe 26, and the steam Cv flows in one direction along the steam pipe 25.

  A reservoir tank 29 is provided in the middle of the liquid pipe 26.

  The reservoir tank 29 temporarily stores the working fluid C flowing through the liquid pipe 26. Although the flow rate of the working fluid C required for heat transfer also varies due to the variation in the amount of heat entering the evaporator 23, the variation in the flow rate of the working fluid C can be absorbed by providing the reservoir tank 29.

  FIG. 4 is a cross-sectional view of the evaporator 23 and its surroundings.

  As shown in FIG. 4, the evaporator 23 is fixed to the circuit board 31 with, for example, screws 33. A heat generating component 32 such as a CPU is mounted on the circuit board 31. The surface of the heat generating component 32 is in close contact with the evaporator 23, and the vapor Cv of the working fluid C is generated by the evaporator 23 by the heat of the heat generating component 32. Can be generated.

  The type of the working fluid C is not particularly limited, but it is preferable to use a fluid having a high vapor pressure and a large latent heat of vaporization as the working fluid C in order to efficiently cool the heat generating component 32 by latent heat of vaporization. Such fluids include, for example, ammonia, water, freon, alcohol, and acetone.

  FIG. 5 is a cross-sectional view taken along the line II of FIG. 3 and corresponds to a cross-sectional view of the liquid pipe 26.

  As shown in FIG. 5, the liquid pipe 26 is formed by laminating a plurality of metal sheets.

  In this example, the liquid tube 26 is manufactured by laminating a first outer layer sheet 35, a plurality of inner layer sheets 36, and a second outer layer sheet 37 in this order. These sheets 35-37 are copper sheets excellent in thermal conductivity, for example, and are joined together by diffusion bonding. The thickness of each of the sheets 35 to 37 is about 0.1 mm to 0.3 mm.

  In addition, it may replace with a copper sheet and may use a stainless steel sheet, a magnesium alloy sheet, etc. as the sheets 35-37. However, it is preferable to use the same material for all the sheets 35 to 37 so that the sheets 35 to 37 can be satisfactorily bonded to each other by diffusion bonding.

  Furthermore, in this example, the number of laminated inner sheet 36 is four, but the number of laminated layers may be smaller than this, or may be larger than four.

  In such a liquid pipe 26, the lower surface 35 x is defined by the first outer layer sheet 35, and the upper surface 37 x is defined by the second outer layer sheet 37. Further, the tube wall 26 x of the liquid tube 26 is defined by the inner side surfaces of the first outer layer sheet 35 and the second outer layer sheet 37.

  A plurality of pillars 38 are provided on each of the lower surface 35x and the upper surface 37y, and the porous body 40 is supported by these pillars 38.

  The height h of the column 38 is not particularly limited, but in this example, the height h is 0.1 mm to 0.15 mm, for example, 0.15 mm. The height h can be appropriately set within a range not exceeding the thickness of each of the outer layer sheets 35 and 37.

  Furthermore, the distance d between adjacent pillars 38 is 0.7 mm to 1.5 mm, for example 1.3 mm.

  The porous body 40 has a large number of holes 36a having a diameter of about 0.1 mm to 0.4 mm, and a liquid-phase working fluid flowing through the liquid pipe 26 penetrates into these holes 36a. The porous body 40 is integral with the inner layer sheet 36, and the porous body 40 is formed by forming a plurality of holes 36 a in the inner layer sheet 36.

  Then, the capillary fluid acting on the working fluid from each hole 36a prevents the working fluid from flowing back through the liquid pipe 26 as described later.

  Further, since the column 38 is provided in the liquid pipe 26 as described above, a flow path R through which a liquid-phase working fluid flows is formed between the adjacent columns 38. The fluid flow is smooth.

  Furthermore, the column 38 also plays a role of preventing the liquid pipe 26 from being crushed by a pressing force when the sheets 35 to 37 are stacked. Thereby, even when the loop heat pipe 22 is thinned, a flow path R through which the working fluid flows is secured in the liquid pipe 26, and the working fluid flows smoothly in the loop heat pipe 22.

  In this example, the pillars 38 are provided on both the lower surface 35x and the upper surface 37x, but the pillars 38 may be provided on only one of the lower surface 35x and the upper surface 37x. Even in this case, since the flow path R is formed between the adjacent columns 38, the flow of the working fluid becomes smoother than when the column 38 is not provided.

  Moreover, the evaporator 23, the condenser 24, and the steam pipe 25 are also formed by laminating | stacking each sheet 35-37 in this way.

  FIG. 6 is a cross-sectional view taken along line II-II in FIG. 3 and corresponds to a cross-sectional view of the evaporator 23. In FIG. 6, the same elements as those described in FIG. 5 are denoted by the same reference numerals as those in FIG. 5, and description thereof will be omitted below.

  As shown in FIG. 6, the aforementioned porous body 40 is also provided in the evaporator 23. The upper surface 37 x in the evaporator 23 is separated from the porous body 40, and a cavity S is formed between the upper surface 37 x and the porous body 40.

  The cavity S communicates with the liquid pipe 26 (see FIGS. 3 and 5), and the liquid-phase working fluid C supplied from the liquid pipe 26 penetrates into the porous body 40. At this time, the capillary force acting on the working fluid C from the porous body 40 becomes a pumping force for circulating the working fluid C in the loop heat pipe 22.

  On the other hand, a plurality of the aforementioned columns 38 are provided on the lower surface 35 x of the evaporator 23, and the porous body 40 is supported by the columns 38.

  Each column 38 is thermally connected to the aforementioned heat generating component 32, and the heat of the heat generating component 32 is transmitted to the porous body 40 through each column 38. As a result, the liquid-phase working fluid C penetrating into the porous body 40 is vaporized and vapor Cv is generated.

  The liquid phase working fluid C penetrates into the upper portion of the porous body 40, and the escape path upward of the vapor Cv is blocked by the capillary force, so the escape path of the vapor Cv is only below the porous body 40.

  Thus, the porous body 40 of the evaporator 23 functions as a check valve that prevents the vapor Cv from flowing back through the liquid pipe 26.

  Since the flow path R of the adjacent column 38 communicates with the steam pipe 25 (see FIG. 3), the steam Cv is released to the steam pipe 25 through the flow path R.

  FIG. 7A is an enlarged plan view of the first outer layer sheet 35 in the evaporator 23.

  In FIG. 7A, the same elements as those described in FIGS. 3 to 6 are denoted by the same reference numerals as those in FIGS. The same applies to FIG. 7B.

  Furthermore, the cross section of the first outer layer sheet 35 of FIG. 6 described above corresponds to a cross section taken along line III-III of FIG.

  As shown in FIG. 7A, the aforementioned pillars 38 extend in a stripe shape in a direction from the liquid pipe 26 toward the steam pipe 25 in plan view.

  On the other hand, FIG. 7B is an enlarged plan view of the second outer layer sheet 37 in the evaporator 23.

  Note that the cross section of the second outer layer sheet 37 in FIG. 6 described above corresponds to a cross section taken along the line IV-IV in FIG.

  As shown in FIG. 7B, the second outer layer sheet 37 in the evaporator 23 is also provided with a plurality of columns 38, and the columns 38 can prevent the evaporator 23 from being crushed.

  Further, each column 38 has an island shape in plan view, whereby the above-described cavity S can be widened, and a large number of liquid-phase working fluids C can be stored in the cavity S.

  FIG. 8 is an enlarged plan view of the inner layer sheet 36 in the evaporator 23.

  In addition, the cross section of each inner-layer sheet | seat 36 of above-described FIG. 6 is corresponded in the cross section which follows the VV line | wire of FIG.

  As shown in FIG. 8, a plurality of holes 36 a are provided in a portion corresponding to the porous body 40 in the inner layer sheet 36.

  FIG. 9 is an overall plan view of the inner layer sheet 36.

  As shown in FIG. 9, the porous body 40 in the liquid pipe 26 extends to the vicinity of the reservoir tank 29 along the liquid pipe 26. The working fluid C in the liquid pipe 26 is guided to the evaporator 23 via the reservoir tank 29 by the capillary force acting on the liquid-phase working fluid C from the porous body 40.

  As a result, even when the vapor Cv tries to flow backward in the liquid pipe 26 due to heat leak from the evaporator 23, the vapor Cv can be pushed back by the capillary force acting on the liquid-phase working fluid C from the porous body 40. It becomes possible to prevent the backflow of steam Cv.

  A plurality of openings 36 b are formed in the inner layer sheet 36 in the condenser 24, the steam pipe 25, and the reservoir tank 29. The position of each opening 36b is different for each of the plurality of inner layer sheets 36, and when each of the plurality of inner layer sheets 36 is laminated, a flow path through which the working fluid C and its vapor Cv flow is formed by each opening 36b.

  The dimensions of the inner layer sheet 36 are not particularly limited. In this example, the width W1 of the steam pipe 25 is about 8 mm, and the width W2 of the liquid pipe 26 is about 6 mm.

  The reservoir tank 29 has an inlet 36c for injecting the working fluid C. The inlet 36c is closed by a sealing member (not shown), and the loop heat pipe 22 is hermetically sealed. To be kept.

  FIG. 10 is a cross-sectional view of the steam pipe 25. In addition, in FIG. 10, the cross section of each inner layer sheet | seat 36 is corresponded in the cross section in alignment with the VI-VI line in FIG.

  As shown in FIG. 10, the first column 38 and the second layer 37 in the steam pipe 25 are also provided with the above-described pillars 38, and the pressing force when the sheets 35 to 37 are stacked. Thus, the column 38 can prevent the steam pipe 25 from being crushed.

  FIG. 11 is an enlarged plan view of a portion corresponding to the porous body 40 in each inner layer sheet 36 from the first layer to the fourth layer.

  As shown in FIG. 11, each inner layer sheet 36 is provided with a plurality of the aforementioned holes 36a.

  In the example of FIG. 11, the shape of each hole 36 a is circular in plan view, and these holes 36 a are provided at the intersections of a plurality of virtual lines L orthogonal to each other.

  The diameter R of the holes 36a and the distance D between adjacent holes 36a depend on the heat transport amount and heat transport distance required for the loop heat pipe 22, the respective heights of the steam pipe 25 and the liquid pipe 26, etc. It can be optimized accordingly.

  In this example, the diameter R is 0.2 mm to 0.3 mm, for example, 0.2 mm. The interval D is set to 0.15 mm, for example.

  Furthermore, the shape of the hole 36a is not limited to a circle, and the hole 36a having an arbitrary shape such as an ellipse or a polygon can be formed.

  Further, the position of the hole 36a is different for each inner layer sheet 36 of the first layer to the fourth layer.

  FIG. 12 is a plan view schematically showing the positions of the holes 36a when the inner layer sheets 36 are laminated.

  Since the positions of the holes 36a are different for each inner layer sheet 36 as described above, the upper and lower holes 36a overlap each other when viewed in plan as shown in FIG.

  How to overlap each hole 36a is not particularly limited. In this example, in two vertically adjacent inner layer sheets 36, at least a part of the hole 36 a of one inner layer sheet 36 overlaps the hole 36 a of the other inner layer sheet 36.

  If it does in this way, the hole 36a adjacent up and down will mutually communicate, and a fine channel is demarcated by these holes 36a. The channel extends three-dimensionally within the porous body 40, and the working fluid C spreads three-dimensionally within the channel by capillary force.

  FIG. 12 illustrates the case where all the holes 36a in all the inner layer sheets 36 have the same size, but the size of the holes 36a is not limited to this.

  FIG. 13 is a plan view showing another example of the size of the hole 36a.

  In the example of FIG. 13, in two inner layer sheets 36 that are adjacent vertically, the diameter R1 of the hole 36a of one inner layer sheet 36 is made different from the diameter R2 of the hole 36a of the other inner layer sheet 36.

  As described above, the capillary force acting on the working fluid C from the porous body 40 can be adjusted by changing the size of the hole 36a in the inner layer sheet 36 adjacent to the upper and lower sides.

  As described above, the porous body 40 is also provided in the evaporator 23. However, the size of the hole 36a may be changed between the evaporator 23 and the liquid pipe 26 as described below.

  14A is a schematic plan view showing an example of the size of the hole 36a in the evaporator 23, and FIG. 14B is a schematic plan view showing an example of the size of the hole 36a in the liquid pipe 26. is there.

  In the example of FIGS. 14A and 14B, the smallest diameter R4 among the diameters of the plurality of holes 36a in the liquid pipe 26 is the smallest diameter R3 among the diameters of the plurality of holes 36a in the evaporator 23. Larger than.

  As a result, the working fluid C smoothly flows through the large hole 36 a in the liquid pipe 26, and the working fluid C can be quickly moved toward the evaporator 23. In the evaporator 23, the liquid-phase working fluid C can act as a check valve by the capillary force received from the small hole 36a, and the backflow of the steam Cv can be effectively suppressed as described above.

  According to the present embodiment described above, as shown in FIG. 5, the porous body 40 is accommodated in the liquid pipe 26, and the plurality of columns 38 that support the porous body 40 are connected to the lower surface 35 x of the liquid pipe 26. Provided on the upper surface 37x.

  Thereby, the working fluid C in the liquid pipe 26 can be guided to the evaporator 23 by the capillary force acting from the porous body 40, and the backflow of the working fluid C from the evaporator 23 to the liquid pipe 26 can be suppressed.

  In addition, since the flow path R through which the working fluid C flows between the adjacent columns 38 can be secured, the flow of the working fluid in the liquid pipe 26 becomes smooth, and the heat transport efficiency of the loop heat pipe 22 is improved. be able to.

  By the way, as a structure for securing the flow path R as described above, a structure as shown in FIG.

  FIG. 15A is a cross-sectional view of the liquid pipe 26 of the loop heat pipe according to the comparative example. In FIG. 15A, the same elements as those in this embodiment are denoted by the same reference numerals as those in this embodiment, and description thereof is omitted below.

  In the comparative example shown in FIG. 15A, each of the lower surface 35x and the upper surface 37y is brought into close contact with the porous body 40 without providing the column 38 on each of the lower surface 35x and the upper surface 37y of the liquid pipe 26.

  Then, in order to secure the flow path R through which the liquid-phase working fluid flows, the side surface 40x of the porous body 40 is separated from the tube wall 26x. Even in such a structure, the flow of the working fluid is smooth by the flow path R.

  Here, the amount of the working fluid flowing in the liquid pipe 26 is determined by the heat generation amount of the heat generating component 32 (see FIG. 4), and the amount of steam Cv generated by the evaporator 23 increases in the heat generating component 32 having a high heat generation amount. Therefore, the amount of liquid-phase working fluid flowing through the liquid pipe 26 also increases.

  Therefore, when the heat generation amount of the heat generating component 32 is assumed to be large, the cross-sectional area of the flow path R is designed to be as large as possible when designing the loop heat pipe, and the amount of working fluid flowing through the liquid pipe 26 is increased. It is desirable to be able to do it.

  FIG. 15B is a cross-sectional view of the liquid pipe 26 according to the comparative example when the cross-sectional area of the flow path R is increased as described above.

  In this example, by increasing the width W2 without changing the height H of the liquid pipe 26, the cross-sectional area of the flow path R is increased while the liquid pipe 26 is thinned.

  However, if the width W2 is increased in this way, the tube wall 26x is greatly separated from the porous body 40, so that it is difficult to support all of the lower surface 35x and the upper surface 37y with the porous body 40. As a result, there is a problem that the first outer layer sheet 35 and the second outer layer sheet 37 are recessed as indicated by dotted lines due to the force when the sheets 35 to 37 are stacked by pressing, and the flow path R becomes narrow.

  On the other hand, FIG. 16 is a sectional view of the liquid pipe 26 when the width W2 is widened in the present embodiment.

  As described above, in the present embodiment, since the flow path R is formed between the adjacent columns 38, it is not necessary to separate the porous body 40 from the tube wall 26x as in the comparative example for the purpose of forming the flow path R. The state in which the porous body 40 is in contact with the tube wall 26x can be maintained.

  As a result, even when the width W2 is expanded and the flow path R is expanded, the lower surface 35x and the upper surface 37y can be supported by the pillars 38. Therefore, when the sheets 35 to 37 are stacked, the first outer layer sheet 35 and the first It is possible to suppress the recess of the second outer layer sheet 37.

  Next, a method for manufacturing the loop heat pipe 22 according to this embodiment will be described.

  FIG.17 and FIG.19 is a top view in the middle of manufacture of the loop type heat pipe 22 which concerns on this embodiment. Moreover, FIG.18 and FIG.20 is sectional drawing in the middle of manufacture of the loop type heat pipe 22 which concerns on this embodiment.

  First, as shown in FIG. 17, a first outer layer sheet 35 and a second outer layer sheet 37 are produced by patterning a copper sheet having a thickness of about 0.2 mm into a predetermined shape by wet etching.

  Next, steps required until a sectional structure shown in FIG. 18 is a cross-sectional view of a portion that will later become the liquid pipe 26 in each of the outer layer sheets 35 and 37, and corresponds to a cross-sectional view taken along the line VII-VII in FIG.

  First, the resist film 41 is formed on the lower surface 35 x of the first outer layer sheet 35. Then, using the resist film 41 as a mask, a portion of the lower surface 35x that does not become the pillar 38 is wet-etched to an intermediate depth, thereby forming a plurality of pillars 38 having a height of about 0.15 mm.

  In addition, the pillar 38 can be formed also in the 2nd outer layer sheet | seat 37 by the method similar to this.

  Further, as shown in FIGS. 7A and 7B, the pillars 38 are also formed in portions of the outer layer sheets 35 and 37 that will later become the evaporator 23.

  Thereafter, the resist film 41 is removed.

  Next, as shown in FIG. 19, each inner layer sheet 36 is formed by patterning a copper sheet into a predetermined shape by wet etching. Although the thickness of the copper sheet is not particularly limited, a copper sheet of about 0.1 mm is used in this example.

  In this patterning, a plurality of the openings 36 b are formed at intervals in the inner layer sheet 36 corresponding to the condenser 24, the steam pipe 25, and the reservoir tank 29.

  If the inside of the condenser 24 and the steam pipe 25 is greatly hollowed out, each part of the inner layer sheet 36b is bent and it becomes difficult to handle the inner layer sheet 36. For example, the bending of the inner layer sheet 36 is suppressed and it becomes easy to handle.

  Further, a plurality of holes 36a are formed in the inner layer sheet 36 corresponding to each of the evaporator 23 and the liquid pipe 26 by the above-described patterning, whereby a porous body 40 having a plurality of holes 36a is obtained.

  The inner layer sheet 36 is provided with an inlet 36c for injecting the working fluid C.

  Subsequently, as shown in FIG. 20, the first outer layer sheet 35, the plurality of inner layer sheets 36, and the second outer layer sheet 37 are laminated in this order. 20 is a cross-sectional view of each of the sheets 35 to 37 in the same cross section as FIG. 18, and corresponds to a cross-sectional view of the liquid pipe 26.

  In stacking, the sheets 35 to 37 are pressed to each other while the sheets 35 to 37 are heated to about 900 ° C., thereby bonding the sheets 35 to 37 by diffusion bonding. At this time, as described above, the pillars 38 support the first outer layer sheet 35 and the second outer layer sheet 37, so that the liquid pipe 26 can be prevented from being crushed by pressing.

  A flow path R through which a liquid-phase working fluid flows is formed between adjacent columns 38.

  FIG. 21 is a plan view showing an example of the planar shape of the pillar 38.

  As shown in FIG. 21, the column 38 is preferably formed in a strip shape extending along the liquid pipe 26 in a plan view so as not to hinder the flow of the liquid-phase working fluid.

  FIG. 22 is a cross-sectional view drawn based on an SEM (Scanning Electron Microscope) image of a portion corresponding to the porous body 40 after lamination.

  As shown in FIG. 22, each inner layer sheet 36 is integrated by diffusion bonding, and the interface of each inner layer sheet 36 disappears.

  Thereafter, the inside of the liquid pipe 26 is evacuated from the inlet 36c (see FIG. 19) using a vacuum pump (not shown), water is injected as the working fluid C from the inlet 36c into the liquid pipe 26, and then the inlet 36c. Is sealed.

  Thus, the loop heat pipe 22 according to the present embodiment is completed.

  According to the manufacturing method of the loop heat pipe 22 described above, since the loop heat pipe 22 is manufactured by laminating a plurality of sheets 35 to 37, the loop heat pipe 22 can be accommodated in a smartphone or a tablet terminal. Can be made thinner.

  The following additional notes are disclosed for each embodiment described above.

(Appendix 1) an evaporator that vaporizes the working fluid;
A condenser for liquefying the working fluid;
A liquid pipe connecting the evaporator and the condenser and having a lower surface and an upper surface on the inside;
A plurality of columns provided on at least one of the lower surface and the upper surface;
A porous body provided in the liquid pipe and supported by the plurality of pillars;
A vapor pipe connecting the evaporator and the condenser and forming a loop with the liquid pipe;
A loop-type heat pipe characterized by comprising:

  (Additional remark 2) The loop type heat pipe of Additional remark 1 characterized by the said porous body being provided also in the said evaporator.

  (Supplementary note 3) The loop heat pipe according to supplementary note 1, wherein the liquid pipe has a pipe wall inside, and the porous body is in contact with the pipe wall.

(Additional remark 4) Each of the said evaporator, the said condenser, the said liquid pipe, and the said steam pipe is 1st outer layer sheet | seat provided with the said lower surface, several inner layer sheet | seat, and 2nd provided with the said upper surface. While laminating the outer layer sheet in this order,
The loop type according to appendix 1, wherein the porous body is formed by laminating a plurality of inner layer sheets, and a plurality of holes are formed in each of the plurality of inner layer sheets corresponding to the porous body. heat pipe.

(Supplementary Note 5) The porous body is also provided in the evaporator,
The loop type heat pipe according to appendix 4, wherein a size of the minimum hole in the liquid pipe is larger than a size of the minimum hole in the evaporator.

  (Supplementary note 6) The loop according to supplementary note 4, wherein at least a part of the hole of one inner layer sheet overlaps the hole of the other inner layer sheet in the two inner layer sheets adjacent vertically. Type heat pipe.

  (Supplementary note 7) In the two inner layer sheets adjacent in the vertical direction, the size of the hole of one inner layer sheet is different from the size of the hole of the other inner layer sheet. Loop type heat pipe.

(Appendix 8)
Heat-generating parts,
A loop heat pipe for cooling the heat generating component;
The loop heat pipe is
An evaporator for vaporizing the working fluid;
A condenser for liquefying the working fluid;
A liquid pipe connecting the evaporator and the condenser and having a lower surface and an upper surface on the inside;
A plurality of columns provided on at least one of the lower surface and the upper surface;
A porous body provided in the liquid pipe and supported by the plurality of pillars;
An electronic apparatus comprising: a vapor pipe that connects the evaporator and the condenser and forms a loop with the liquid pipe.

(Supplementary Note 9) A step of forming columns on at least one of an upper surface and a lower surface inside a liquid pipe that is connected to each of an evaporator and a condenser that are connected to each other by a vapor pipe and that forms a loop with the vapor pipe;
Providing a porous body supported by the column in the liquid tube;
Injecting a working fluid into the liquid pipe;
A method for manufacturing a loop heat pipe, comprising:

  (Additional remark 10) The process of forming the said pillar is performed by etching the part which does not become the said pillar in at least one of the said upper surface and the said lower surface, The loop type heat pipe of Additional remark 9 characterized by the above-mentioned. Production method.

(Additional remark 11) It further has the process of forming the said liquid pipe by laminating | stacking the 1st outer layer sheet provided with the said lower surface, several inner layer sheets, and the 2nd outer layer sheet provided with the said upper surface in this order,
The step of providing the porous body is performed by forming a plurality of holes in a portion corresponding to the porous body in the plurality of inner layer sheets. Production method.

DESCRIPTION OF SYMBOLS 1,22 ... Loop type heat pipe 2,20 ... Electronic equipment 3,23 ... Evaporator 4,24 ... Condenser 5,25 ... Vapor pipe, 6,26 ... Liquid pipe, 7,32 ... Heat generation part DESCRIPTION OF SYMBOLS 10 ... Wick, 21 ... Housing, 26x ... Pipe wall, 29 ... Reservoir tank, 31 ... Circuit board, 33 ... Screw, 35 ... First outer layer sheet, 35x ... Lower surface, 36 ... Inner layer sheet, 36a ... Hole, 36b ... Opening, 37 ... Second outer layer sheet, 37x ... Upper surface, 38 ... Pillar, 40 ... Porous body, 36c ... Injection port, 41 ... Resist film.

Claims (6)

An evaporator for vaporizing the working fluid;
A condenser for liquefying the working fluid;
A liquid pipe connecting the evaporator and the condenser and having a lower surface and an upper surface on the inside;
A plurality of columns provided on at least one of the lower surface and the upper surface;
A porous body provided in the liquid pipe and supported by the plurality of pillars;
A vapor pipe connecting the evaporator and the condenser and forming a loop with the liquid pipe;
A loop-type heat pipe characterized by comprising:   The loop heat pipe according to claim 1, wherein the porous body is also provided in the evaporator.   2. The loop heat pipe according to claim 1, wherein the liquid pipe has a tube wall on an inner side, and the porous body is in contact with the tube wall. Each of the evaporator, the condenser, the liquid pipe, and the steam pipe includes a first outer layer sheet having the lower surface, a plurality of inner layer sheets, and a second outer layer sheet having the upper surface. While being laminated in this order,
2. The loop according to claim 1, wherein the porous body is formed by laminating a plurality of inner layer sheets, and a plurality of holes are formed in each of the plurality of inner layer sheets corresponding to the porous body. Type heat pipe. Heat-generating parts,
A loop heat pipe for cooling the heat generating component;
The loop heat pipe is
An evaporator for vaporizing the working fluid;
A condenser for liquefying the working fluid;
A liquid pipe connecting the evaporator and the condenser and having a lower surface and an upper surface on the inside;
A plurality of columns provided on at least one of the lower surface and the upper surface;
A porous body provided in the liquid pipe and supported by the plurality of pillars;
An electronic apparatus comprising: a vapor pipe that connects the evaporator and the condenser and forms a loop with the liquid pipe. Forming a column on at least one of an upper surface and a lower surface inside a liquid pipe connected to each of an evaporator and a condenser connected to each other by a vapor pipe and forming a loop with the vapor pipe;
Providing a porous body supported by the column in the liquid tube;
Injecting a working fluid into the liquid pipe;
A method for manufacturing a loop heat pipe, comprising:

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