JP2018185110A - heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pipe which enables reduction of a thickness while inhibiting deterioration of heat transport efficiency.SOLUTION: A heat pipe 1A includes: a container 2 in which a working fluid is enclosed; and a wick body 10 which is provided in the container while forming a lateral gap with an inner wall of the container and contacts with an upper wall 2a or a lower wall 2b of the container. The wick body has a first wick part 11 and a second wick part 12 which are disposed while forming a gap in a lateral direction in a cross sectional view. A liquid reservoir part S1 formed between the first wick part and the second wick part is filled with the working fluid in a liquid phase.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat pipe.

  Conventionally, a heat pipe in which a wick body and a working fluid are enclosed in a container has been used. In the container, there are provided a vapor channel for the vapor-phase working fluid to go to the condensing unit and a liquid channel for the liquid-phase working fluid to go to the evaporation unit. By circulating the working fluid, heat can be repeatedly transported from the evaporation section to the condensation section.

  As such a heat pipe, for example, in Patent Document 1 below, the wick body has a first wick portion and a second wick portion arranged at intervals in a cross-sectional view, and the first wick portion and the second wick portion are arranged. A configuration is disclosed in which a curved portion and a flat portion are formed in the wick portion, and each curved portion is in contact with or close to the inner wall of the container. In addition, with this configuration, the gap between the bent portion and the inner wall of the container is used as a liquid flow path, while the gap between the first wick portion and the second wick portion and the gap between the wick body and the container are reduced. And use as a steam flow path.

JP 2011-43320 A

  By the way, in recent years, electronic devices such as mobile phones have been miniaturized, and heat pipes that transport heat in these electronic devices are required to have a very thin shape, for example, a thickness of less than 0.5 mm. It has been. When the heat pipe has such a very thin shape, the configuration described in Patent Document 1 does not sufficiently secure the flow path of the liquid-phase working fluid, and the flow of the liquid-phase working fluid is delayed. It turns out that there is a case. Thus, if the flow of the liquid-phase working fluid stagnate, the heat transport efficiency by the heat pipe will be reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a heat pipe capable of reducing the thickness while suppressing a decrease in heat transport efficiency.

  In order to solve the above-described problem, the heat pipe according to the first aspect of the present invention has a left-right gap between the container in which the working fluid is sealed and the inner wall of the container. And a wick body that is in contact with an upper wall or a lower wall of the container, wherein the wick body is arranged with a first wick portion and a second wick portion spaced apart in the left-right direction in a cross-sectional view. And a liquid reservoir formed between the first wick portion and the second wick portion is filled with a liquid-phase working fluid.

According to the heat pipe according to the above aspect, the liquid phase working fluid is filled in the liquid pool portion between the first wick portion and the second wick portion. With this configuration, even in an extremely thin heat pipe having a vertical thickness of less than 0.5 mm, the liquid-phase working fluid condensed in the condensing unit can be reliably refluxed to the evaporation unit through the liquid pool. Therefore, it is possible to prevent the flow of the liquid-phase working fluid from stagnation, and to suppress a decrease in the heat transport efficiency of the heat pipe.
In addition, since the liquid reservoir is formed inside the wick body, when the working fluid evaporates from the outer surface of the wick body, the liquid phase working fluid is supplied from the liquid reservoir toward the outer surface. Can do. Thereby, it becomes possible to stabilize the supply amount of the liquid-phase working fluid to the outer surface of the wick body, and to prevent the outer surface of the wick body from drying. And it can suppress that the outer surface of a wick body dries, the evaporation amount of a working fluid falls, and heat transport efficiency falls.

  Here, each upper surface of the first wick portion and the second wick portion extends in the left-right direction in a cross-sectional view and contacts the upper wall of the container, and each of the first wick portion and the second wick portion The lower surface may extend in the left-right direction in a cross-sectional view and may be in contact with the lower wall of the container.

  In this case, the first wick part and the second wick part are in surface contact with the upper wall and the lower wall of the container over a wide area. Thereby, heat becomes easy to be transmitted between the container and each wick part, and the heat transport efficiency of the heat pipe can be improved.

  Further, the liquid pool portion may be formed in a substantially rectangular shape in a cross sectional view.

  In this case, the width of the liquid pool portion can be stabilized, and the capillary force can be reliably applied to the liquid-phase working fluid in the liquid pool portion.

  Moreover, the width | variety in the left-right direction or the width | variety in an up-down direction of the said liquid pool part may be smaller than the width | variety of the steam flow path formed between the said wick body and the said container.

  In this case, the liquid-phase working fluid can be reliably positioned in the liquid pool portion having a width narrower than that of the steam channel by the action of the surface tension. Therefore, for example, the liquid-phase working fluid can be prevented from entering the vapor flow path, and the flow of the liquid-phase working fluid and the gas-phase working fluid in the container can be made smooth.

Moreover, the width | variety of the up-down direction in the part which forms the steam flow path of a working fluid among the said containers may be larger than the width | variety of the said liquid pool part.
Moreover, the recessed part recessed toward the said liquid pool part may be formed in the part which faces the said liquid pool part among the said containers.
The wick body may have a connection wick portion that connects the first wick portion and the second wick portion to each other.

  By appropriately selecting these modes, even if the heat pipe is formed extremely thin, the dimensions of the liquid pool portion ensure that surface tension and capillary force act on the liquid phase working fluid located in the liquid pool portion. Can be stabilized.

  According to the said aspect of this invention, the heat pipe which can make thickness thin can be provided, suppressing the fall of heat transport efficiency.

It is sectional drawing of the heat pipe which concerns on 1st Embodiment. It is an AA cross-sectional arrow view of the heat pipe of FIG. It is sectional drawing of the heat pipe which concerns on 2nd Embodiment. It is sectional drawing of the heat pipe which concerns on 3rd Embodiment. (A) is sectional drawing of the heat pipe which concerns on a modification, (b) is sectional drawing of the heat pipe which concerns on another modification.

(First embodiment)
Hereinafter, the configuration of the heat pipe according to the first embodiment will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size.
As shown in FIG. 1, the heat pipe 1 </ b> A includes a container 2 in which a working fluid is enclosed, and a wick body 10 provided inside the container 2.

Here, in this embodiment, an XYZ orthogonal coordinate system is set and the positional relationship of each component is demonstrated. The X direction is a direction in which the heat pipe 1A extends (hereinafter referred to as a longitudinal direction). Hereinafter, a cross section perpendicular to the longitudinal direction is simply referred to as a transverse cross section.
The heat pipe 1A is formed in a flat shape having a small thickness T in the Z direction (hereinafter, referred to as the vertical direction) and a wide width B in the Y direction (hereinafter, referred to as the horizontal direction) in a cross sectional view. The dimensions of the heat pipe 1A of the present embodiment are, for example, T = 0.25 mm and B = 3.2 mm.

  In the present embodiment, the concept including both the width in the up-down direction and the width in the left-right direction is simply referred to as “width”.

  The inside of the container 2 is hollow and sealed. The material of the container 2 can be appropriately selected depending on conditions such as the type of working fluid and the operating temperature. In particular, when a metal material having high thermal conductivity such as copper or aluminum is used, heat transportability and thermal diffusibility can be improved. The container 2 can be formed using metal pipes, such as a copper pipe, an aluminum pipe, a stainless steel pipe, for example. The thickness of the container 2 of this embodiment is 0.06 mm, for example.

  The wick body 10 is provided with a left-right clearance with respect to the inner wall of the container 2. In the example of FIG. 1, the wick body 10 is disposed in the center portion of the container 2 in the left-right direction. The wick body 10 is in contact with the upper wall 2a and the lower wall 2b of the container 2. The wick body 10 can exchange heat with the container 2 as long as it is in contact with at least one of the upper wall 2a or the lower wall 2b of the container 2.

  A large number of pores that generate capillary force are formed inside the wick body 10. As a material of the wick body 10, for example, a metal fine wire, a metal mesh, a sintered body of metal powder, and the like can be used. In the case where the wick body 10 is formed of a mesh material such as metal, for example, the plate-like mesh material is removed with a mold, so that even if the wick body 10 has a complicated shape, it can be easily formed. Further, when the wick body 10 is formed of a metal powder sintered body or the like, the size of the pores can be further reduced, and a high capillary force can be generated to enhance the heat transportability.

  The pores in the wick body 10 are impregnated with a liquid-phase working fluid. The liquid-phase working fluid is a fluid that can be evaporated by heating and condensed by heat radiation. The type of the working fluid can be appropriately selected according to the temperature at which the heat pipe is used. As the working fluid, for example, water, alcohol, or alternative chlorofluorocarbon can be used. For example, the working fluid may be enclosed in the container 2 in a state where a non-condensable gas such as air is degassed from the inside of the container 2 in a vacuum chamber.

  As shown in FIG. 2, the wick body 10 is disposed in the container 2 along the longitudinal direction. The width in the left-right direction of the wick body 10 is smaller than the width in the left-right direction of the container 2, and the wick body 10 is disposed at the center in the left-right direction of the container 2. Thereby, steam flow paths S2 are formed on both sides of the wick body 10 in the left-right direction. The steam flow path S2 serves as a flow path for the gas-phase working fluid.

  The wick body 10 is partially melted by being sintered in the container 2 and fixed to the inner wall of the container 2. More specifically, as shown in FIG. 1, the wick body 10 is joined to the upper wall 2a and the lower wall 2b of the container 2. For example, in a state where the wick body 10 is disposed in the container 2, the container 2 is compressed and deformed in the vertical direction, and the wick body 10 is sandwiched between the upper wall 2a and the lower wall 2b of the container 2 so that the wick body 10 is It may be fixed.

  Here, as shown in FIG. 1, the wick body 10 of the present embodiment includes a first wick portion 11 and a second wick portion 12 that are spaced apart in the left-right direction in a cross-sectional view. A space between the first wick part 11 and the second wick part 12 (hereinafter referred to as a liquid pool part S1) is filled with a liquid-phase working fluid. As shown in FIG. 2, the liquid pool portion S1 extends along the longitudinal direction.

As shown in FIG. 1, the first wick portion 11 is formed in a substantially rectangular shape having an upper surface 11 a and a lower surface 11 c extending in the left-right direction, and an outer surface 11 b and an inner side surface 11 d extending in the up-down direction in a cross-sectional view. Has been. In a cross-sectional view, the second wick portion 12 is formed in a substantially rectangular shape having an upper surface 12a and a lower surface 12c extending in the left-right direction, and an outer surface 12b and an inner surface 12d extending in the vertical direction.
The liquid pool portion S1 is formed in a substantially rectangular shape in a cross-sectional view by the upper wall 2a and the lower wall 2b of the container 2 and the inner side surfaces 11d and 12d of each wick portion.

  Inner side surfaces 11d and 12d of the first wick portion 11 and the second wick portion 12 face each other in the left-right direction. The upper surfaces 11 a and 12 a of the first wick portion 11 and the second wick portion 12 are in contact with the upper wall 2 a of the container 2. The lower surfaces 11 c and 12 c of the first wick part 11 and the second wick part 12 are in contact with the lower wall 2 b of the container 2.

  The width W1 in the left-right direction of the liquid pool part S1 is smaller than both the width V1 in the left-right direction and the width V2 in the up-down direction of the steam channel S2, and is set so that capillary force is generated. The dimensions in this embodiment are, for example, W1 = 0.1 mm, W2 = 0.13 mm, V1 = 1.06 mm, and V2 = 0.13 mm. The dimensions of the liquid pool portion S1 are such that the liquid phase working fluid sealed in the container 2 can be held in the liquid pool portion S1 and the wick body 10 while generating the capillary force as described above. It is determined.

  The heat pipe 1A having the above configuration is manufactured, for example, as follows. First, a wick that becomes the first wick portion 11 and the second wick portion 12 and a rod sandwiched between these wicks are inserted into a copper tube that becomes the container 2. In this state, the copper tube is heated to sinter the wick against the inner wall of the copper tube. Thereafter, the rod is pulled out from the copper tube, and the container 2 is deformed into a flat shape. And heat pipe 1A is formed by inject | pouring a working fluid in a copper pipe in a vacuum state, and obstruct | occluding the edge part of a copper pipe.

  Next, the effect | action of 1 A of heat pipes comprised as mentioned above is demonstrated.

  1 A of heat pipes are attached to the electronic component etc. in the articles | goods (for example, notebook PC and a mobile telephone) used as the object of heat transport. In the example of FIG. 2, one end in the longitudinal direction of the heat pipe 1 </ b> A functions as the evaporation unit E, and the other end functions as the condensing unit C. The evaporating unit E is disposed adjacent to a heat generating unit such as a CPU, for example, and the condensing unit C is disposed adjacent to a heat radiating unit such as a heat sink.

  In the evaporation section E, the liquid-phase working fluid located on the surface of the wick body 10 is heated and evaporated through the wall surface of the container 2. As the working fluid evaporates, the pressure of the gas in the steam flow path S2 in the vicinity of the evaporation section E increases. Thereby, as shown by the arrow F1 in FIG. 1, the gas-phase working fluid moves in the longitudinal direction in the vapor flow path S2 toward the condensing part C side.

  The vapor-phase working fluid that has reached the condensing part C is deprived of heat through the wall surface of the container 2, condenses, and adheres to the wall surface of the container 2 as droplets. As shown by an arrow F2 in FIG. 2, the working fluid droplets soak into the pores in the wick body 10 by capillary force. Here, part of the liquid-phase working fluid that has soaked into the pores in the wick body 10 flows into the liquid pool portion S1, as indicated by an arrow F2 '.

  The liquid-phase working fluid in the pores of the wick body 10 and the liquid pool portion S1 moves to the evaporation portion E side in the longitudinal direction by capillary force. Then, the liquid-phase working fluid is supplied from the pores in the wick body 10 and the liquid pool part S1 to the evaporation part E through two paths indicated by arrows F3 and F4. The liquid-phase working fluid that has reached the evaporation section E evaporates again from the surface of the wick body 10 in the evaporation section E.

  The working fluid that has evaporated to a vapor phase moves again to the condensing part C side through the vapor flow path S2. Thus, the heat pipe 1A can repeatedly transport the heat recovered on the evaporation part E side in the longitudinal direction to the condensation part C side by repeatedly using the liquid phase / gas phase transition of the working fluid.

  As described above, according to the heat pipe 1 </ b> A of the present embodiment, the wick body 10 includes the first wick portion 11 and the second wick portion 12, and the liquid between these wick portions 11 and 12. The pool portion S1 is filled with a liquid-phase working fluid. With this configuration, even in an extremely thin heat pipe 1A whose vertical thickness is less than 0.5 mm, the liquid-phase working fluid condensed in the condensing part C is reliably recirculated to the evaporation part E through the liquid pool part S1. be able to. Therefore, it is possible to prevent the flow of the liquid-phase working fluid from stagnation, and to suppress a decrease in the heat transport efficiency of the heat pipe 1A.

  Further, since the liquid pool portion S1 is formed inside the wick body 10, when the working fluid evaporates from the outer surface of the wick body 10, the liquid phase working fluid from the liquid pool portion S1 toward the outer surface. Can be supplied. Thereby, it becomes possible to stabilize the supply amount of the liquid-phase working fluid to the outer surface of the wick body 10 and to prevent the outer surface of the wick body 10 from drying. And it can suppress that the outer surface of the wick body 10 dries, the evaporation amount of a working fluid falls, and the efficiency of heat transport falls.

Moreover, each upper surface 11a, 12a of the 1st wick part 11 and the 2nd wick part 12 is contacting the upper wall 2a of the container 2 while extending in the left-right direction in the cross sectional view. Further, the lower surfaces 11c and 12c of the first wick portion 11 and the second wick portion 12 extend in the left-right direction in a cross-sectional view and are in contact with the lower wall 2b of the container 2.
With this configuration, the first wick part 11 and the second wick part 12 come into surface contact with the upper wall 2a and the lower wall 2b of the container 2 in a wide area. Thereby, it becomes easy to transmit heat between the container 2 and each wick part 11 and 12, and the heat transport efficiency of 1 A of heat pipes can be improved.

  Further, since the liquid pool portion S1 is formed in a substantially rectangular shape in a cross sectional view, the vertical or horizontal width of the liquid pool portion S1 is stabilized, and the liquid phase in the liquid pool portion S1 is stabilized. Capillary force can be reliably applied to the working fluid.

Further, the width W1 in the left-right direction of the liquid pool portion S1 is made smaller than the width V1 in the left-right direction and the width V2 in the vertical direction of the steam channel S2, and capillary force is applied to the liquid-phase working fluid in the liquid pool portion S1. By making it act, the liquid-phase working fluid in the liquid pool part S1 can be recirculated more smoothly from the condensation part C side to the evaporation part E side.
Furthermore, the liquid-phase working fluid can be reliably positioned in the liquid pool part S1 having a narrower width than the steam flow path S2 by the action of the surface tension. Accordingly, for example, the liquid-phase working fluid can be prevented from entering the vapor flow path S2, and the flow of the liquid-phase working fluid and the gas-phase working fluid in the container 2 can be made smooth. The condition for obtaining such an effect is that at least one of the width W1 in the left-right direction of the liquid reservoir S1 or the width W2 in the up-down direction is equal to the width V1 in the left-right direction and the width V2 in the up-down direction of the steam channel S2. Is smaller than both. That is, any one of the following mathematical formulas (1) and (2) may be satisfied.
W1 <V1 and W1 <V2 (1)
W2 <V1 and W2 <V2 (2)

(Second Embodiment)
Next, a second embodiment according to the present invention will be described. The basic configuration is the same as that of the first embodiment. For this reason, the same code | symbol is attached | subjected to the same structure, the description is abbreviate | omitted, and only a different point is demonstrated.

As shown in FIG. 3, in the heat pipe 1 </ b> B of the present embodiment, a recess 2 c that is recessed toward the inside of the container 2 is formed on the upper wall 2 a of the container 2. Recess 2c is located between first wick portion 11 and second wick portion 12 in the left-right direction. For this reason, the width W2 in the vertical direction of the liquid pool portion S1 is smaller than the width V2 in the vertical direction of the steam flow path S2. The dimensions in this embodiment are, for example, W1 = 0.2 mm, W2 = 0.06 mm, V1 = 1.085 mm, and V2 = 0.08 mm.
Even in the configuration of the present embodiment, the same effects as those of the first embodiment can be achieved.

  In addition, the recessed part 2c may be formed over the full length of the upper wall 2a in a longitudinal direction, and may be formed in a part of upper wall 2a in a longitudinal direction. Moreover, the recessed part 2c may be formed in the lower wall 2b of the container 2, and may be formed in both the upper wall 2a of the container 2, and the lower wall 2b.

(Third embodiment)
Next, a third embodiment according to the present invention will be described. The basic configuration is the same as that of the first embodiment. For this reason, the same code | symbol is attached | subjected to the same structure, the description is abbreviate | omitted, and only a different point is demonstrated.

In the present embodiment, the configuration of the wick body is different from that of the first embodiment.
As shown in FIG. 4, the heat pipe 1 </ b> C of the present embodiment includes a wick body 20 having a first wick part 21, a second wick part 22, and a connection wick part 23.

  The first wick part 21 and the second wick part 22 are arranged at intervals in the left-right direction and are connected to each other by the connection wick part 23. The connection wick part 23 is in contact with the lower wall 2 b of the container 2. The liquid pool portion S1 in the present embodiment is formed by the wick portions 21 to 23 and the upper wall 2a of the container 2. With this configuration, the width W3 in the vertical direction of the liquid pool portion S1 (the distance between the upper wall 2a and the connection wick portion 23) is smaller than the width V2 in the vertical direction of the steam channel S2. The dimensions in this embodiment are, for example, W1 = 0.2 mm, W3 = 0.06 mm, V1 = 1.085 mm, and V2 = 0.08 mm.

  Even in the configuration of the present embodiment, the same effects as those of the first embodiment can be achieved. Further, the width W3 in the vertical direction of the liquid pool part S1 can be made smaller than the width V2 in the vertical direction of the steam channel S2 while the distance between the upper wall 2a and the lower wall 2b of the container 2 is kept constant. it can.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the example of FIG. 2, the heat pipe 1 </ b> A extends linearly in the longitudinal direction, but is not limited thereto, and the heat pipe 1 </ b> A may be bent and used. At that time, since the wick body 10 is joined to the upper wall 2a and the lower wall 2b of the container 2, even if the heat pipe 1A is bent, the wick body 10 moves in the left-right direction with respect to the container 2 and steam flows. The path S2 is prevented from becoming narrow. When the heat pipe 1A is bent, the longitudinal direction is the direction in which the center line of the heat pipe 1A extends, and the left-right direction is defined as a direction orthogonal to both the center line and the vertical direction (thickness direction). Can do.

Further, the arrangement and shape of the wick body 10 accommodated in the container 2 may be changed as appropriate. For example, like the heat pipe 1D shown in FIG. 5A, the wick body 10 may be arranged in a position biased in the left-right direction in the container 2.
Moreover, like the heat pipe 1E shown in FIG. 5 (B), the wick body 30 in which the three wick portions 31 to 33 are spaced apart in the left-right direction may be employed, or four or more wicks may be employed. The parts may be arranged at intervals in the left-right direction.

  In addition, the constituent elements in the above-described embodiment can be appropriately replaced with known constituent elements without departing from the gist of the present invention, and the above-described embodiments and modifications may be appropriately combined.

  1A to 1E ... Heat pipe 2 ... Container 2a ... Upper wall 2b ... Lower wall 2c ... Recess 10 ... Wick body 11 ... First wick portion 11a ... Upper surface 11c ... Lower surface 12 ... Second wick portion 12a ... Upper surface 12c ... Lower surface V1 ... Width of steam flow path S1 ... Liquid pool part S2 ... Steam flow path V1-V2 ... Width of steam flow path W1-W3 ... Width of liquid pool part

Claims (7)

A container enclosing a working fluid;
A wick body provided inside the container with a gap in the left-right direction between the inner wall of the container and in contact with the upper wall or the lower wall of the container,
The wick body has a first wick portion and a second wick portion arranged with a space in the left-right direction in a cross-sectional view,
A heat pipe in which a liquid reservoir is filled in a liquid reservoir formed between the first wick part and the second wick part. Each upper surface of the first wick portion and the second wick portion extends in the left-right direction in a cross-sectional view and contacts the upper wall of the container,
2. The heat pipe according to claim 1, wherein each lower surface of the first wick portion and the second wick portion extends in the left-right direction in a cross-sectional view and is in contact with the lower wall of the container.   The heat pipe according to claim 1 or 2, wherein the liquid pool is formed in a substantially rectangular shape in a cross-sectional view.   The width | variety in the left-right direction of the said liquid pool part or the width | variety in an up-down direction is smaller than the width | variety of the steam flow path formed between the said wick body and the said container. Heat pipe. Of the container, the width in the vertical direction in the portion that forms the vapor flow path of the working fluid,
The heat pipe according to any one of claims 1 to 4, wherein the heat pipe is larger than a width of the liquid pool portion.   The heat pipe according to any one of claims 1 to 5, wherein a concave portion that is recessed toward the liquid pool portion is formed in a portion of the container that faces the liquid pool portion.   The heat pipe according to any one of claims 1 to 6, wherein the wick body includes a connection wick portion that connects the first wick portion and the second wick portion to each other.

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