JP2016053465A - Heat transport device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase of resistance received by a working fluid and generate circulation flow of the working fluid with a simple structure in a heat transport device and an electronic apparatus.SOLUTION: A heat transport device includes: a heating part 13; a cooling part 14; a passage 12 having a closed loop shape in which the working fluid C is reciprocated between the heating part 13 and the cooling part 14 and including turn parts 12b which turn flow of the working fluid C in the heating part 13; and bypasses 15, each of which obliquely connects two different portions of each turn part 12b with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat transport device and an electronic apparatus.

  With the recent development of information processing technology, small electronic devices such as mobile devices and wearable terminals are becoming widespread. These electronic devices contain electronic components such as a CPU (Central Processing Unit), but in order to reduce the size of the electronic devices, it is effective to reduce the thickness of the heat transport device that cools the electronic components. is there.

  One of the heat transport devices effective for thinning is a self-excited vibration heat pipe. The self-excited vibration heat pipe has a structure in which the flow path of the hydraulic fluid is reciprocated many times between the heating unit and the cooling unit.

  According to this structure, the hydraulic fluid is vaporized in the heating section and the pressure in the flow path is increased, whereas in the cooling section, the hydraulic fluid is liquefied and the pressure in the flow path is reduced. A pressure difference is generated. The hydraulic fluid autonomously reciprocates in the flow path due to the pressure difference, and the heat of the heating unit can be transported to the cooling unit by the hydraulic fluid. In addition, the flow of the hydraulic fluid that reciprocates in the flow path may be called an oscillating flow.

  The self-excited vibration heat pipe only needs to reciprocate the flow path between the heating unit and the cooling unit as described above, and has a simple structure and is advantageous for downsizing.

  However, when the temperature of the electronic component rises and the heating unit becomes hot, vaporization of the working fluid is accelerated more than necessary in the heating unit, and the working fluid may be depleted in the heating unit.

  In order to prevent the exhaustion of the hydraulic fluid, it is effective to generate a circulating flow in which the hydraulic fluid flows in one direction in the flow path in addition to the oscillating flow of the hydraulic fluid. According to this, since the working fluid is constantly supplied to the flow path in the heating unit by the circulating flow, it is possible to prevent the working fluid from being depleted in the heating unit, and to improve the heat transport performance of the self-excited vibration heat pipe. it can.

  Various structures have been proposed for generating a circulating flow, but all have room for improvement.

  For example, a method has been proposed in which a check valve is provided in the middle of the flow path so that the working fluid flows in one direction only in the flow path. Therefore, it becomes difficult for the hydraulic fluid to flow through the flow path. In addition, the check valve complicates the structure and makes it difficult to manufacture a heat transport device.

  In addition, a structure in which a circulating flow is generated by providing a plurality of nozzles in the middle of the flow path has been proposed. However, even in this structure, the resistance that the hydraulic fluid receives from the nozzles increases, and the hydraulic fluid does not easily circulate in the flow path.

Japanese Unexamined Patent Publication No. Sho 63-318493 JP 2010-156533 A JP 2012-220160 A JP-A-4-148189 Toshihiro Fukuda and two others, "Heat transport characteristics of self-excited oscillating heat pipes with unequal cross-section", Proceedings of the 45th Japan Heat Transfer Symposium, Vol. I, p. 347-348 Yasushi Kato and two others, "Study on Unequal Section Loop Heat Pipe (2nd Report, Influence of Channel Size)", Proc. Of the 40th Japan Heat Transfer Symposium, Vol. I, p. 313-314 Hitoshi Kitajima and two others, "Study on Unequal Cross Section Loop Heat Pipe", Proceedings of the 39th Japan Heat Transfer Symposium, Vol. I, p. 147-148

  The disclosed technology has been made in view of the above, and in a heat transport device and an electronic apparatus, the circulation of the working fluid with a simple structure is prevented while preventing the resistance that the working fluid receives from the flow path from increasing. The purpose is to generate

  According to one aspect of the disclosure below, the heating unit, the cooling unit, and a closed loop that reciprocates the hydraulic fluid between the heating unit and the cooling unit, the flow of the hydraulic fluid in the heating unit There is provided a heat transport device having a flow path having a turn part to be converted and a bypass that obliquely connects two different parts of the turn part.

  According to another aspect of the disclosure, the heat transport device provided with a heating unit and a cooling unit, and an electronic component thermally connected to the heating unit of the heat transport device, The heat transport device has a closed loop shape for reciprocating a working fluid between the heating unit and the cooling unit, and includes a flow path including a turn unit that converts the flow of the working fluid in the heating unit, and the turn An electronic device is provided that includes a bypass that diagonally connects two parts of different parts.

  According to the following disclosure, a turn portion that changes the flow of the hydraulic fluid is provided in the flow path, and two different portions of the turn portion are connected by an oblique bypass. Thus, the direction in which the working fluid flows is determined by the pressure of the vapor bubbles generated in the bypass, and a circulating flow in which the working fluid flows only in one direction of the flow path is obtained.

FIG. 1 is a plan view of the heat transport device according to the first embodiment. FIG. 2 is an enlarged plan view of a turn portion and its surroundings in the first embodiment. FIGS. 3A to 3C are enlarged plan views for explaining a bypass function in the first embodiment. FIG. 4 is an enlarged plan view of a turn part used for the examination in the first embodiment. FIG. 5 is a graph obtained by calculating how the pressure of the hydraulic fluid pushed out of the bypass changes when the angle between the flow path and the bypass is changed. FIG. 6 is an enlarged plan view of a turn portion according to the second embodiment. FIG. 7 is an enlarged plan view of a turn portion according to the third embodiment. FIG. 8 is a plan view of the heat transport device according to the fourth embodiment. FIG. 9 is a plan view of the heat transport device according to the fifth embodiment. FIG. 10 is an enlarged plan view of two adjacent turn portions in the fifth embodiment. FIG. 11 is a plan view of an electronic apparatus according to the sixth embodiment. 12A and 12B are cross-sectional views (part 1) in the middle of manufacturing the heat transport device according to the seventh embodiment. FIGS. 13A and 13B are cross-sectional views (part 2) in the middle of manufacturing the heat transport device according to the seventh embodiment.

  Embodiments will be described below with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a plan view of a heat transport device 10 according to the present embodiment.

  This heat transport device 10 is a self-excited vibration heat pipe, and includes a sheet 11 such as a resin sheet and a closed-loop flow path 12 formed therein.

  The flow path 12 is formed so as to reciprocate a plurality of times between a heating unit 13 and a cooling unit 14 provided at each end of the sheet 11, and a working fluid C such as water or ethanol is enclosed therein. The In this example, about half of the volume of the flow path 12 is filled with the liquid phase hydraulic fluid C. In addition, instead of water or ethanol, a fluorine-based compound such as chlorofluorocarbon or hydrofluorocarbon may be used as the hydraulic fluid C.

  Further, a vapor bubble V of the working fluid C is formed in a portion where there is no working fluid C in the flow path 12.

  A first injection hole 12c and a second injection hole 12d for injecting the working fluid C into the flow path 12 at the time of manufacture are provided at the end of the flow path 12 on the cooling unit 14 side.

  Furthermore, the flow path 12 has a plurality of straight portions 12 a between the heating unit 13 and the cooling unit 14. The straight portions 12a are parallel to each other, and a turn portion 12b that changes the flow of the working fluid C is provided at the end of the straight portion 12a on the heating portion 13 side.

  Although the planar size of the heat transport device 10 is not particularly limited, in this example, the heat transport device 10 has a substantially rectangular shape having a long side of about 100 mm and a short side of about 50 mm.

  FIG. 2 is an enlarged plan view of the turn portion 12b and its surroundings.

  As shown in FIG. 2, the turn part 12b has a U-shape, and the direction of the flow of the hydraulic fluid C that has flowed into the turn part 12b is reversed to the original, and the cooling part 14 (see FIG. 1). It flows.

  In the present embodiment, one end 12 x and the other end 12 y of the turn portion 12 b are obliquely connected by the linear bypass 15.

  The positions of the one end 12x and the other end 12y are not particularly limited as long as they are two different portions of the turn portion 12b. For example, one end 12x may be provided at a position before the flow of the hydraulic fluid C is changed at the turn portion 12b, and the other end 12y may be provided at a position after the flow of the hydraulic fluid C is changed at the turn portion 12b.

  In this example, the bypass 15 is inclined with respect to the straight portion 12a by positioning the other end 12y closer to the cooling unit 14 (see FIG. 1) than the one end 12x.

Further, the widths W ₁ and W _{2 of} the flow path 12 and the bypass 15 are not particularly limited. In this example, the width W _{1 of the} flow path 12 is about 0.4 mm, and the width W _{2 of the} bypass 15 is about 0.2 mm. To do.

  Next, the function of the bypass 15 will be described.

  FIGS. 3A to 3C are enlarged plan views for explaining the function of the bypass 15.

  First, as shown to Fig.3 (a), the hydraulic fluid C in the bypass 15 vaporizes, and the vapor bubble V is produced | generated by heating the turn part 12b by electronic components, such as CPU.

  The vapor bubbles V grow with time, and the hydraulic fluid C is pushed out from both ends of the bypass 15 as shown in FIGS. 3B and 3C.

Here, since the bypass 15 is inclined in this embodiment, the flow P of the hydraulic fluid C pushed out from the bypass 15 includes a straight line portion in addition to the vertical component P ₁ perpendicular to the straight line portion 12a (see FIG. 1). parallel component P ₂ parallel to 12a are also included.

The direction D of the flow of the hydraulic fluid C is determined by the parallel component P ₂ , and a circulating flow in which the hydraulic fluid C flows only in one direction of the flow path 12 is obtained.

In particular, by providing a bypass 15 to each of the plurality of turn portions 12b as in this example, mutually amplified parallel component P ₂ of the respective bypass 15, hydraulic fluid C flows easily in one direction only.

  The inventor of the present application examined how much the bypass 15 should be inclined in order to generate a circulating flow.

  FIG. 4 is an enlarged plan view of the turn part 12b used for the examination.

  4, the same elements as those described in FIGS. 1 to 3 are denoted by the same reference numerals as those in FIGS. 1 to 3, and the description thereof is omitted below.

In FIG. 4, the angle between the bypass 15 and the flow path 12 at the other end 12y is indicated by α. The angle α is equal to the angle between the parallel component P ₂ and flow P described above.

  FIG. 5 is a graph obtained by calculating how the pressure of the hydraulic fluid C pushed out from the bypass 15 changes when the angle α is changed.

Incidentally, the parallel component P ₂ are from and serves as a driving force for generating a circulating flow of the working fluid as described above, and the propulsion components a component parallel to the parallel component P ₂ of the pressure of the hydraulic fluid C.

On the other hand, the component perpendicular to the vertical component P ₁ of the pressure of the hydraulic fluid C, this could be a brake the circulation by increasing the pressure of the hydraulic fluid C at the other end 12y, it is considered here as a braking component.

  Further, both the propulsion component and the braking component are normalized by the pressure of the hydraulic fluid C in the bypass 15.

  As shown in FIG. 5, the propulsion component decreases as the angle α increases, while the braking component increases.

  When the angle α is 45 °, the propulsion component is equal to the braking component, and when the angle α exceeds 45 °, the braking component is more dominant than the propulsion component.

  Therefore, from the viewpoint of reliably generating a circulating flow by the hydraulic fluid C pushed out from the bypass 15, the angle α is preferably less than 45 °.

  In this embodiment, it is assumed that the propulsion component is sufficiently larger than the braking component when the propulsion component is twice the braking component. According to FIG. 5, by setting the angle α to 30 ° or less, it is possible to make the propulsion component more than twice the braking component.

  According to the present embodiment described above, the circulation flow can be generated by the hydraulic fluid C pushed out from the bypass 15 by providing the oblique bypass 15 in the turn portion 12b.

  In addition, since it is not necessary to provide the flow path 12 with a check valve or nozzle for generating a circulating flow, the resistance that the hydraulic fluid C receives from the flow path 12 increases while generating the circulating flow with a simple structure. Can be prevented.

(Second Embodiment)
FIG. 6 is an enlarged plan view of the turn part 12b according to the present embodiment. In FIG. 6, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted below.

  As shown in FIG. 6, in the present embodiment, the bypass 15 has a curved shape. Thereby, the angle α between the flow path 12 and the bypass 15 can be made smaller than the angle β between the tangent L in the middle of the bypass 15 and the flow path 12.

  As described with reference to FIG. 5 of the first embodiment, the propulsion component that generates the circulation flow increases as the angle α decreases. Therefore, compared with the case where the bypass 15 is formed in a straight line parallel to the tangent L, the working fluid C can be easily circulated in the flow path 12 in the present embodiment.

(Third embodiment)
FIG. 7 is an enlarged plan view of the turn part 12b according to the present embodiment. In FIG. 7, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted below.

As shown in FIG. 7, in this embodiment, the diameter d _a of the bypass 15 on the other end 12y side, larger than the diameter d _b of the one end 12x side of the bypass 15.

Since the resistance received by the hydraulic fluid C in the bypass 15 is smaller in the wide portion than in the narrow portion, the hydraulic fluid C moves toward the wide portion. Therefore, to be larger than the diameter d _a diameter d _b as in the present embodiment, the direction of flow of the hydraulic fluid C of within the bypass 15 is determined in the direction E toward the other end 12y from one end 12x.

  As a result, the pressure of the hydraulic fluid C in the bypass 15 does not easily escape to the one end 12x side, and the hydraulic fluid C is strongly pushed out from the bypass 15 on the other end 12y side. Propulsion can be obtained.

  The fact that the flow of the hydraulic fluid C is determined in the direction E can also be explained by the capillary force in the bypass 15 as follows.

The capillary force is inversely proportional to the diameter of the bypass 15. Therefore, when larger than the diameter d _a diameter d _b as in the present embodiment, the capillary force becomes greater than the capillary force in the vicinity of the other end 12y in the vicinity of one end 12x, the capillary force in the bypass 15, one end The flow direction E is determined by being pushed from 12x to the other end 12y.

In the present embodiment, it is assumed that the hydraulic fluid C is pushed out in the direction E with a sufficient force when the capillary force at the one end 12x becomes twice the capillary force at the other end 12y. Since the capillary force is inversely proportional to the diameter as mentioned above, by making the diameter d _b less than half of the diameter d _a, it is possible in this way the ratio of the capillary force into two or more.

(Fourth embodiment)
FIG. 8 is a plan view of the heat transport device 10 according to the present embodiment. In FIG. 8, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted below.

  In the present embodiment, as shown in FIG. 8, a plurality of bypasses 15 parallel to each other are provided at intervals in each turn part 12b. Thereby, the flow of the hydraulic fluid C pushed out from the plurality of bypasses 15 is amplified, and the driving force for circulating the hydraulic fluid C in the flow path 12 can be increased.

(Fifth embodiment)
FIG. 9 is a plan view of the heat transport device 10 according to the present embodiment. In FIG. 9, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted below.

  As shown in FIG. 9, in the present embodiment, a connection flow path 17 that obliquely connects one end 12x and the other end 12y of two adjacent turn portions 12b is provided.

  FIG. 10 is an enlarged plan view of two adjacent turn portions 12b.

Similar to the bypass 15, the connection flow path 17 has a function of pushing out the hydraulic fluid C to both sides by the vapor bubbles V growing inside thereof. The flow Q of the hydraulic fluid C leaving the connecting channel 17, the vertical component Q ₁ perpendicular to the straight portion 12a, there is a parallel component Q ₂ parallel to the straight portion 12a, the flow through the parallel component Q ₂ of this A circulating flow of hydraulic fluid C is generated in the passage 12.

  In order to ensure this function, it is preferable to provide the connection flow path 17 obliquely with respect to the straight portion 12 a of the flow path 12, similarly to the bypass 15.

  The positions of the bypass 15 and the connection channel 17 are not particularly limited. As shown in FIG. 10, the bypass 15 and the connection flow path 17 may be provided at positions symmetrical with each other with the straight line portion 12 a as the axis of symmetry L.

As a result, the parallel component P ₂ of the flow of the hydraulic fluid C exiting from the bypass 15 and the parallel component Q ₂ of the flow of the hydraulic fluid C exiting from the connection channel 17 are directed in the same direction. Can generate a circulating flow of the hydraulic fluid C in cooperation with each other.

In addition, instead of providing the bypass 15 and the connection flow path 17 at positions symmetrical with each other, either the bypass 15 or the connection flow path 17 may be provided closer to the cooling unit 14 (see FIG. 1). . Also in this case, it is preferable to set the angle between the connection flow path 17 and the straight portion 12a so that the parallel components P ₂ and Q ₂ face the same direction.

(Sixth embodiment)
In the present embodiment, an electronic apparatus including the heat transport device 10 according to the first embodiment will be described.

  FIG. 11 is a plan view of the electronic device 30 according to the present embodiment.

  In FIG. 11, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted below.

  The electronic device 30 is a mobile device such as a smartphone, and includes a housing 31 and the heat transport device 10 accommodated therein.

  An electronic component 20 such as a CPU is accommodated in the housing 31, and the electronic component 20 is thermally connected to the heating unit 13 of the heat transport device 10. On the other hand, the cooling unit 14 of the heat transport device 10 is cooled by an air cooling method.

  According to such an electronic device 30, the electronic component 20 can be appropriately cooled by the heat transport device 10 that exhibits excellent heat transfer performance due to the circulating flow of the hydraulic fluid C.

  In addition, although the electronic device 30 provided with the heat transport device 10 according to the first embodiment has been described above, the heat transport device according to the second to fifth embodiments may be provided in the electronic device 30.

  Furthermore, the electronic device 30 is not limited to a mobile device, and the heat transport device 10 may be provided in an electronic computer such as a personal computer.

(Seventh embodiment)
In the present embodiment, a method for manufacturing the heat transport device 10 described in the first embodiment will be described. The heat transport device according to the second to fifth embodiments can also be manufactured by the same manufacturing method.

  12-13 is sectional drawing in the middle of manufacture of the heat transport device which concerns on this embodiment.

  12 to 13, a first cross section I cut along a plane perpendicular to the extending direction of the flow path 12 and a second cross section II cut along a plane perpendicular to the extending direction of the bypass 15 are shown together. To do.

  First, as shown in FIG. 12A, an ultraviolet curable resin coating 22 is formed on the base film 21 or the like, and the base film 21 and the coating 22 are used as the lower sheet 18. The material of the base film 21 is not particularly limited, but a transparent resin film made of PET (polyethylene terephthalate) or the like can be used as the base film 21.

  Next, as shown in FIG. 12B, a mold 25 having unevenness corresponding to the flow path 12 and the bypass 15 on the surface is prepared, and the mold 25 is embedded in the coating film 22. In this state, the coating film 22 is cured by irradiating the coating film 22 with ultraviolet rays UV through the base film 21.

  Thereby, a part of the flow path 12 corresponding to the uneven surface 25a of the mold 25 is formed in the first cross section I. On the other hand, in the second cross section II, a part of the bypass 15 corresponding to the uneven surface 25a of the mold 25 is formed.

  Thereafter, the mold 25 is removed from the coating film 22 as shown in FIG.

  And as shown in FIG.13 (b), a PET sheet is stuck as the upper sheet 19 on the lower sheet | seat 18 using the adhesive agent not shown.

  Thereby, the sheet 11 formed from the lower sheet 18 and the upper sheet 19 is obtained, and the flow path 12 and the bypass 15 are determined in the sheet 11. The overall thickness Z of the sheet 11 is not particularly limited, but in the present embodiment, the thickness Z is 0.5 mm or less.

  Thereafter, while reducing the pressure in the flow path 12, the hydraulic fluid C having about half the volume of the flow path 12 is injected into the flow path 12. The injection of the hydraulic fluid C and the decompression of the flow path 12 are performed from the first injection hole 12c (see FIG. 1) and the second injection hole 12d, and after the injection, the injection holes 12c and 12d are made of an adhesive. Sealed.

  Thus, the basic structure of the heat transport device 10 according to the present embodiment is completed.

  In this example, the flow path 12 and the bypass 15 are formed by molding the coating film 22 of an ultraviolet curable resin. However, the flow path 12 and the bypass 15 may be formed by cutting on the surface of a metal plate such as a copper plate. .

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

(Supplementary note 1) Heating part,
A cooling section;
A closed loop that reciprocates hydraulic fluid between the heating unit and the cooling unit, and a flow path that includes a turn unit that converts the flow of the hydraulic fluid in the heating unit;
A bypass that diagonally connects two different parts of the turn part; and
A heat transport device comprising:

(Additional remark 2) The said flow path has a linear part between the said heating part and the said cooling part,
The heat transport device according to appendix 1, wherein the bypass is inclined with respect to the straight line portion.

  (Supplementary note 3) The heat transport device according to supplementary note 1, wherein the bypass is curved.

  (Supplementary note 4) The heat transport device according to supplementary note 1, wherein one of the ends of the bypass has a larger diameter than the other.

  (Supplementary note 5) The heat transport device according to supplementary note 1, wherein a plurality of the bypasses are provided at intervals.

(Additional remark 6) While providing the said turn part with two or more in the said heating part,
The heat transport device according to appendix 1, further comprising an oblique connection channel connecting the two adjacent turn portions.

(Additional remark 7) The said flow path has a linear part between the said heating part and the said cooling part,
The heat transport device according to appendix 6, wherein the bypass and the connection flow path are in a line-symmetric position with respect to the straight line portion as an axis of symmetry.

  (Additional remark 8) The angle between the said flow path and the said bypass is 30 degrees or less, The heat transport device of Additional remark 1 characterized by the above-mentioned.

(Appendix 9) a heat transport device provided with a heating part and a cooling part;
An electronic component thermally connected to the heating section of the heat transport device;
The heat transport device is a closed loop that reciprocates the working fluid between the heating unit and the cooling unit, and has a flow path that includes a turn unit that changes the flow of the working fluid in the heating unit;
An electronic device comprising: a bypass that obliquely connects two different portions of the turn portion.

DESCRIPTION OF SYMBOLS 10 ... Heat transport device, 11 ... Sheet, 12 ... Channel, 12a ... Straight part, 12b ... Turn part, 12c ... First injection hole, 12d ... Second injection hole, 12x ... One end, 12y ... Other end, DESCRIPTION OF SYMBOLS 13 ... Heating part, 14 ... Cooling part, 15 ... Bypass, 17 ... Connection flow path, 18 ... Lower sheet, 19 ... Upper sheet, 21 ... Base film, 22 ... Coating film, 25 ... Mold, 25a ... Uneven surface 30 ... electronic equipment, 31 ... housing.

Claims (6)

A heating unit;
A cooling section;
A closed loop that reciprocates hydraulic fluid between the heating unit and the cooling unit, and a flow path that includes a turn unit that converts the flow of the hydraulic fluid in the heating unit;
A bypass that diagonally connects two different parts of the turn part; and
A heat transport device comprising:   The heat transport device according to claim 1, wherein the bypass is curved.   The heat transport device according to claim 1, wherein one of the ends of the bypass has a larger diameter than the other.   The heat transport device according to claim 1, wherein a plurality of bypasses are provided at intervals. While providing a plurality of the turn part in the heating part,
The heat transport device according to claim 1, further comprising an oblique connection channel that connects the two adjacent turn portions. A heat transport device provided with a heating part and a cooling part;
An electronic component thermally connected to the heating section of the heat transport device;
The heat transport device is a closed loop that reciprocates the working fluid between the heating unit and the cooling unit, and has a flow path that includes a turn unit that changes the flow of the working fluid in the heating unit;
An electronic device comprising: a bypass that obliquely connects two different portions of the turn portion.

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