JP2019082309A - Loop type heat pipe and method for manufacturing loop type heat pipe - Google Patents

Abstract

To provide a loop type heat pipe capable of efficiently transferring heat by reducing resistance received by working fluid from a pipeline and a method for manufacturing the loop type heat pipe.SOLUTION: A loop type heat pipe 11 includes: an intermediate metal layer 22 in which a loop type pipeline 15 is formed; a lower metal layer 21 and an upper metal layer 23 that are joined to the intermediate metal layer 22; working fluid C filled in a pipeline 17; an evaporator 13 and a condenser 14 provided in the pipeline 17; a steam pipe 15 that is the pipeline 17 between the evaporator 13 and the condenser 14 and in which steam Cv of the working fluid C flows; and a liquid pipe 16 that is the pipeline 17 between the evaporator 13 and the condenser 14 and in which the liquid working fluid C flows. In at least a part of any of the condenser 14, the liquid pipe 16 and the steam pipe 15, at least one of the lower metal layer 21 and the upper metal layer 23 is expanded toward an outer side of the pipeline 17.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a loop heat pipe and a method of manufacturing a loop heat pipe.

  As a device for transporting heat generated by an electronic device such as a smartphone, there is a loop heat pipe. The loop heat pipe is a device that performs heat transfer using phase change of the working fluid, and has a looped conduit in which the working fluid is enclosed.

  In the loop heat pipe, heat generated by the electronic components is transported to the condenser by the working fluid flowing in one direction in the pipe, and therefore heat is efficiently transported if the resistance received by the working fluid from the pipe is large. Can not do it.

WO 2015/087451 JP 10-122774 A Japanese Patent Application Laid-Open No. 11-37678

  According to one aspect, the present invention aims to provide a looped heat pipe capable of efficiently transporting heat by reducing the resistance received by the working fluid from the pipeline, and a method of manufacturing the looped heat pipe. I assume.

  According to one aspect, there is provided an intermediate metal layer in which a looped pipeline is formed, a lower metal layer joined under the intermediate metal layer and closing the pipeline from below, and the upper metal layer. An upper metal layer which is joined and closes the conduit from above, a working fluid which is enclosed in the conduit and is present in a liquid or vapor state, and is provided in the conduit to evaporate the liquid working fluid A condenser for condensing the vapor, and a pipe between the evaporator and the condenser, the vapor pipe through which the vapor flows, the evaporator, and the evaporator. A pipe between the condenser and the liquid pipe through which the working fluid flows, and the lower metal in any part of the condenser, the liquid pipe, and the steam pipe; Characterized in that at least one of the layer and the upper metal layer has expanded toward the outside of the pipeline. Loop heat pipe is provided that.

  According to one aspect, as at least one of the lower metal layer and the upper metal layer is expanded out of the conduit, the resistance received by the working fluid from the conduit is reduced. This allows the working fluid to flow smoothly in the pipeline and allows the working fluid to efficiently transport the heat.

FIG. 1 is a top view of the loop heat pipe used in the study. FIG. 2 is a cross-sectional view taken along the line I-I of FIG. FIG. 3 is a top view of the loop heat pipe according to the present embodiment. FIG. 4 is a cross-sectional view taken along the line II-II in FIG. FIG. 5 is a cross-sectional view taken along the line III-III in FIG. 6 is a cross-sectional view taken along the line IV-IV in FIG. 7 is a cross-sectional view taken along the line V-V of FIG. FIG. 8 is a plan view for describing a portion where the porous body is provided in the first embodiment. FIG. 9 is a plan view in the case where a porous body is provided only in a part of the liquid pipe in the first embodiment. Fig.10 (a) is sectional drawing of the liquid pipe along the VI-VI line of FIG. 9, FIG.10 (b) is sectional drawing of the condenser along the VII-VII line of FIG. FIG. 11 is a cross-sectional view of the condenser fixed to the housing in the first embodiment. FIG. 12 is a graph obtained by investigating the heat transport performance of the loop heat pipe according to the first embodiment. FIG. 13 is a plan view of each of the lower metal layer and the upper metal layer used in the loop heat pipe according to the first embodiment. FIG. 14 is a plan view of an intermediate metal layer used in the loop heat pipe according to the first embodiment. FIG. 15 is an enlarged plan view of each of a plurality of intermediate metal layers in region A of FIG. FIGS. 16A and 16B are cross-sectional views (part 1) in the middle of manufacturing the loop heat pipe according to the first example of the first embodiment. FIG. 17: is sectional drawing (the 2) in the middle of manufacture of the loop type heat pipe which concerns on the 1st example of 1st Embodiment. FIGS. 18A and 18B are cross-sectional views (part 1) in the middle of manufacturing the loop heat pipe according to the second example of the first embodiment. FIG. 19 is a cross-sectional view (part 2) of the loop-type heat pipe according to the second example of the first embodiment which is being manufactured. FIG. 20 is a cross-sectional view of a loop heat pipe in a first modified example of the first embodiment. FIG. 21 is a cross-sectional view of the case where the lower metal layer is thicker than the upper metal layer in the first modification of the first embodiment. FIG. 22 is a cross-sectional view of a loop-type heat pipe in a second modification of the first embodiment. FIG. 23 is a cross-sectional view of the case where the tube wall portion of the lower metal layer is thinner than the joint portion in the second modification of the first embodiment. FIG. 24 (a) is a cross-sectional view of the steam pipe before expanding the lower metal layer and the upper metal layer to the outside of the pipe in the second embodiment, and FIG. 24 (b) is the second embodiment. FIG. 7 is a cross-sectional view of the steam pipe after the lower metal layer and the upper metal layer are expanded to the outside of the pipe in FIG. FIG. 25 is a plan view for describing a planar shape of the recess in the second embodiment. FIG. 26 is a plan view showing a portion for forming a recess in the loop heat pipe according to the second embodiment. 27 (a) to 27 (c) are cross-sectional views for describing the method of processing the lower metal layer according to the present embodiment. FIG. 28 is a cross-sectional view of a steam pipe according to a first modification of the second embodiment. FIG. 29 is an enlarged plan view of a lower metal layer according to a second modification of the second embodiment. FIG. 30 is an enlarged plan view of a lower metal layer according to a third modification of the second embodiment. FIG. 31 is an enlarged plan view of a lower metal layer according to a fourth modification of the second embodiment.

  Prior to the description of the present embodiment, matters examined by the inventor of the present application will be described.

  FIG. 1 is a top view of the loop heat pipe used in the study.

  The loop heat pipe 1 is accommodated in a housing 2 such as a smartphone or a digital camera, 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 the pipes 5 and 6 form a looped pipeline 9 through which the working fluid C flows. In addition, a heat generating component 7 such as a CPU (Central Processing Unit) is fixed to the evaporator 3, and the heat of the heat generating component 7 generates a vapor Cv of the working fluid C.

  The vapor Cv is led to the condenser 4 through the steam pipe 5 and is liquefied in the condenser 4 and supplied again to the evaporator 3 through the liquid pipe 6.

  As the working fluid C circulates through the inside of the loop heat pipe 1 as described above, the heat generated by the heat generating component 7 is transferred to the condenser 4 and the cooling of the heat generating component 7 can be promoted.

  FIG. 2 is a cross-sectional view taken along the line I-I of FIG.

  As shown in FIG. 2, in this example, a plurality of metal layers 8 are stacked and joined, and a pipeline 9 is formed therein.

  As described above, by laminating the metal layers 8 to produce the loop heat pipe 1, the thickness of the loop heat pipe can be reduced, and the thickness reduction of the housing 2 can be promoted.

  However, in this structure, since the height h of the conduit 9 is only a thickness of several metal layers 8 stacked, the resistance that the working fluid C receives from the conduit 9 is increased. Therefore, the working fluid C is inhibited from circulating in the loop heat pipe 1, and the flow of the working fluid C makes it difficult to transport the heat of the heat generating component 7 to the condenser 4, and the heat generating component 7 is efficiently made. It becomes difficult to cool down.

  Below, this embodiment which can reduce the resistance which a working fluid receives from a pipeline is described.

First Embodiment
FIG. 3 is a top view of the loop heat pipe according to the present embodiment.

  The loop heat pipe 11 is accommodated in a housing 12 of the electronic device, and includes an evaporator 13 and a condenser 14. The electronic device is not particularly limited as long as it has a heat generating component to be cooled, and a smartphone, a digital camera, an artificial satellite, an on-vehicle electronic device, a server, or the like can be adopted as the electronic device.

  A vapor pipe 15 and a liquid pipe 16 are connected to the evaporator 13 and the condenser 14, and these pipes 15 and 16 form a looped pipe line 17 through which the working fluid C flows. A heat generating component 18 such as a CPU is fixed to the evaporator 13. The heat of the heat generating component 18 evaporates the liquid working fluid C, and a vapor Cv of the working fluid C is generated.

  The vapor Cv is led to the condenser 14 through the vapor pipe 15 and liquefied in the condenser 14 and then supplied again to the evaporator 13 through the liquid pipe 16.

  As the working fluid C circulates through the inside of the loop heat pipe 11, the heat generated in the heat generating component 18 is transferred to the condenser 14 and the cooling of the heat generating component 18 can be promoted.

  In addition to the heat-generating component 18 which is to be cooled by the loop heat pipe 11, the housing 12 also accommodates an electronic component 19 which does not require active cooling. As such an electronic component 19, there is, for example, a surface mount type electronic component mounted on a wiring board (not shown).

  Although only one electronic component 19 is illustrated in FIG. 3, a plurality of electronic components 19 may be provided in the housing 12.

  FIG. 4 is a cross-sectional view taken along the line II-II in FIG.

  As shown in FIG. 4, in the present embodiment, the lower metal layer 21, the intermediate metal layer 22, and the upper metal layer 23 are stacked in this order to produce the loop heat pipe 11. Among these metal layers, the intermediate metal layer 22 is provided with a conduit 17 having a width W of about 5 mm to 10 mm, and the lower metal layer 21 blocks the conduit 17 from the lower side, and the upper metal layer 23 blocks the conduit 17 from above.

  Although the material of each metal layer 21-23 is not specifically limited, In this embodiment, a copper layer with favorable heat conductivity and workability is employ | adopted as each metal layer 21-23. In addition, it may replace with a copper layer and may employ | adopt an aluminum layer and a stainless steel layer as each metal layer 21-23.

  The thickness of each of the metal layers 21 to 23 is about 100 μm to 300 μm, for example, about 100 μm, and the total thickness T of all the metal layers 21 to 23 is about 600 μm to about 1800 μm.

  By stacking the metal layers 21 to 23 each having a small thickness in this manner, the thickness of the loop heat pipe 11 can be reduced, which contributes to the reduction in thickness of the housing 12 in which the loop heat pipe 11 is accommodated. can do.

  The number of laminated intermediate metal layers 22 is not particularly limited, and only one intermediate metal layer 22 may be provided, or a plurality of intermediate metal layers 22 may be laminated.

  Further, in the present embodiment, by expanding each of the lower metal layer 21 and the upper metal layer 23 toward the outside of the conduit 17, the height H of the conduit 17 is as high as about 0.6 mm to 1.2 mm. Do.

  As a result, the resistance to which the working fluid C is received from the conduit 17 is reduced, so that the working fluid C is easily circulated in the loop heat pipe 11. As a result, the flow of the working fluid C makes it easy to transport the heat of the heat generating component 18 to the condenser 14, and the heat generating component 18 can be efficiently cooled.

  However, as shown in FIG. 3, the electronic component 19 is provided inside the housing 12, and the loop heat pipe 11 in a portion overlapping the electronic component 19 in a plan view is in close proximity to the electronic component 19. It is difficult to expand both the side metal layer 21 and the upper metal layer 23.

  Therefore, in the present embodiment, in the loop heat pipe 11 in a portion overlapping the electronic component 19 in a plan view, one of the metal layers 21 and 23 is suppressed from swelling as follows.

  FIG. 5 is a cross-sectional view taken along the line III-III in FIG. 3 and corresponds to a cross-sectional view of the loop heat pipe 11 in a portion overlapping the electronic component 19.

  As shown in FIG. 5, in this portion, the width W of the pipeline 17 formed in each of the intermediate metal layers 22 narrows stepwise from the upper metal layer 23 toward the lower metal layer 21. As described later, the lower metal layer 21 and the upper metal layer 23 expand outward by increasing the pressure inside the conduit 17. Therefore, when the width W is narrowed stepwise toward the lower metal layer 21 in this manner, the portion of the lower metal layer 21 that receives pressure from the inside of the conduit 17 is reduced, compared to the upper metal layer 23. The expansion of the lower metal layer 21 is reduced.

  As a result, even if the electronic component 19 exists under the lower metal layer 21, the loop heat pipe 11 can be prevented from contacting the electronic component 19.

  The difference ΔW in width W between the intermediate metal layers 22 vertically adjacent to each other is not particularly limited, but in this example, the difference ΔW is about 200 μm to 500 μm.

  6 is a cross-sectional view taken along the line IV-IV in FIG. 3, and corresponds to the cross-sectional view of the loop heat pipe 11 along the flow direction of the working fluid C.

  As shown in FIG. 6, in the present embodiment, in the portion where the electronic component 19 does not exist, the height H of the conduit 17 is largely secured by the swelling of the lower metal layer 21, and the swelling is suppressed on the electronic component 19. Thus, the loop heat pipe 11 can be prevented from contacting the electronic component 19.

  Next, the structure of the liquid pipe 16 will be described.

  FIG. 7 is a cross-sectional view taken along the line V-V in FIG. 3 and corresponds to the cross-sectional view of the liquid pipe 16.

  As shown in FIG. 7, the liquid pipe 16 is provided with a porous body 25 that holds a liquid working fluid C. The porous body 25 is formed of an intermediate metal layer 22 and fine pores 22a provided in each of them. The vertically adjacent holes 22a communicate with each other, whereby fine three-dimensional channels through which the liquid working fluid C flows are formed by the respective holes 22a. The capillary force acting on the working fluid C from the porous body 25 serves as a driving force for moving the working fluid C in the liquid pipe 16 to the evaporator 13.

  Since the lower metal layer 21 and the upper metal layer 23 in the liquid pipe 16 are joined to the porous body 25, expansion to the outside is restricted, and the outer surfaces 21x and 23x of each are flat.

  FIG. 8 is a plan view for describing a portion where the porous body 25 is provided.

  In the example of FIG. 8, the porous body 25 is provided in all parts of the liquid pipe 16 and the evaporator 13.

  If the driving force for moving the working fluid C to the evaporator 19 can be sufficiently obtained by the porous body 25, the porous body 25 may be provided on only a part of the liquid pipe 16 as follows.

  FIG. 9 is a plan view in the case where the porous body 25 is provided only in a part of the liquid pipe 16.

  In the example of FIG. 9, the portion of the liquid pipe 16 where the porous body 25 is provided is a portion P1 from the middle portion 16 a of the liquid pipe 16 to the evaporator 13. And the porous body 25 is not provided in the pipe line 17 in the part P2 from the midway part 16a to the condenser 14.

  Fig.10 (a) is sectional drawing of the liquid pipe 16 in the part P2 along the VI-VI line of FIG.

  In the portion P2, there is no porous body 25 that restricts the metal layers 21 and 23 from expanding outward. Therefore, unless the liquid pipe 16 contacts the electronic component 19 (see FIG. 3), the lower metal layer 21 and the upper metal layer 23 are expanded as shown in FIG. 10A, and the resistance that the working fluid C receives from the liquid pipe 16 It is preferable to reduce the

  FIG.10 (b) is sectional drawing of the condenser 14 which followed the VII-VII line of FIG.

  Since the porous body 25 does not exist also in the condenser 14, it is preferable to reduce the resistance that the working fluid C receives from the liquid pipe 16 by inflating the lower metal layer 21 and the upper metal layer 23 as shown in FIG. .

  In order to promote cooling of the working fluid C in the condenser 14, the condenser 14 may be fixed to the housing 12, and the heat of the condenser 14 may be dissipated to the outside through the housing 12.

  FIG. 11 is a cross-sectional view of the condenser 14 fixed to the housing 12 and corresponds to the cross-sectional view of the condenser 14 taken along the line VII-VII in FIG.

  In the example of FIG. 11, the housing 12 is fixed to the outer surface 21 x of the lower metal layer 21 via a thermal interface material (TIM) 26 such as thermally conductive grease or resin. Further, similarly to FIG. 5, a structure in which the width of the conduit 17 narrows stepwise from the upper metal layer 23 to the lower metal layer 21 is employed, and the swelling of the lower metal layer 21 is suppressed. As a result, the unevenness of the outer surface 21 x of the lower metal layer 21 is reduced, so that the lower metal layer 21 and the housing 12 adhere well via the TIM 26, and the heat of the condenser 14 is transmitted through the housing 12. Thus, the heat can be dissipated efficiently to the outside.

  In addition, when the TIM 26 can sufficiently absorb the unevenness of the outer surface 21 x, the lower side expanded largely downward as shown in FIG. 10B without suppressing the expansion of the lower metal layer 21 in this manner. The housing 12 may be fixed to the metal layer 21 via the TIM 26.

  As described above, according to the present embodiment, the lower metal layer 21 and the upper metal layer 23 are expanded to reduce the resistance that the working fluid C receives from the conduit 17. Further, by forming the cross section of the conduit 17 in a step-like shape, the swelling of the lower metal layer 21 and the upper metal layer 23 is suppressed at a portion where the electronic device 19 and the loop heat pipe 11 are close to each other.

  The portion where the lower metal layer 21 and the upper metal layer are inflated is not particularly limited as long as the loop heat pipe 11 does not contact the electronic device 19. Such portions include portions of any of the condenser 14, the liquid pipe 15, and the steam pipe 16. The deformation of the lower metal layer 21 and the upper metal layer 23 in the evaporator 13 is restricted by the porous body 25 (see FIG. 8) and the heat-generating component 18, and therefore, may not be forced to expand.

  The inventors of the present application investigated how the heat transport performance of the loop heat pipe 11 is improved by inflating the lower metal layer 21 and the upper metal layer 23 as described above.

  The survey results are shown in FIG.

  FIG. 12 is a graph obtained by investigating the heat transport performance of the loop heat pipe 11 according to the present embodiment, the horizontal axis indicates the heat input amount to the evaporator 13, and the vertical axis indicates the loop The heat resistance of the heat pipe 11 is shown.

  In addition, in FIG. 12, the investigation result of the loop heat pipe 1 shown in FIG. 1 is written together as a comparative example. In the loop type heat pipe 1 according to the comparative example, there is no swelling in the pipe line 9 as described with reference to FIG.

  The loop heat pipe 11 according to the present embodiment normally operates in the operating area A1 where the thermal resistance decreases with the increase of the heat input amount, and the pipe line 17 in the inoperable area A2 where the heat input amount is larger than the operating area A1. Do not work with excessive pressure drop inside.

  As shown in FIG. 12, in the present embodiment, the thermal resistance is smaller than that of the comparative example in most of the operation area A1. It is considered that this is because the flow of the working fluid C in the conduit 17 becomes smooth by inflating the conduit 17 as in the present embodiment.

  Moreover, the maximum value Q1 of the heat input amount at which the loop heat pipe 11 can operate in the present embodiment is larger than the maximum value Q2 in the comparative example.

  From these results, it has been confirmed that inflating the pipe line 17 as in the present embodiment is effective for enhancing the heat transport performance of the loop heat pipe 11.

  Next, a method of manufacturing the loop heat pipe 11 according to the present embodiment will be described.

  FIG. 13 is a plan view of each of the lower metal layer 21 and the upper metal layer 23 used in the loop heat pipe 11.

  As shown in FIG. 13, each of the lower metal layer 21 and the upper metal layer 23 has a planar shape corresponding to each of the evaporator 13, the condenser 14, the steam pipe 15, and the liquid pipe 16.

  On the other hand, FIG. 14 is a plan view of the intermediate metal layer 22 used in the loop heat pipe 11.

  As shown in FIG. 14, the intermediate metal layer 22 also has a planar shape corresponding to each of the evaporator 13, the condenser 14, the steam pipe 15, and the liquid pipe 16.

  The intermediate metal layer 22 is provided with a pipe line 17. The conduit 17 is a loop in plan view, and an injection port 11 a for injecting the working fluid C into the conduit 17 is formed in the intermediate metal layer 22. Further, in the intermediate metal layer 22 in a portion corresponding to the evaporator 13 and the liquid pipe 16, a plurality of fine holes 22a forming the porous body 25 are opened.

  In the region A of FIG. 14, the conduit 17 and the electronic component 19 (see FIG. 3) overlap. FIG. 15 is an enlarged plan view of each of the plurality of intermediate metal layers 22 in the region A.

  As shown in FIG. 15, the width W of the conduit 17 is the narrowest in the first intermediate metal layer 22, and widens in the order of the second and third layers.

  Although the loop type heat pipe 11 is manufactured by laminating | stacking the above-mentioned metal layers 21-23, there exist the following 1st example and a 2nd example in the manufacturing method.

First Example FIGS. 16 to 17 are cross-sectional views of the loop heat pipe 11 according to the first example, which are being manufactured.

  In addition, in these figures, the cross section which followed each of the II-II line of FIG. 3, and III-III line is written together.

  First, as shown in FIG. 16A, the lower metal layer 21, the intermediate metal layer 22, and the upper metal layer 23 described above are stacked in this order. Then, while heating each metal layer 21 to 23 to a temperature of 500 ° C. or higher, for example 700 ° C., each metal layer 21 to 23 is pressed at a pressure of about 10 MPa and diffusion bonding is performed to each metal layer 21 to 23 Bonding is performed, and the lower metal layer 21 and the upper metal layer 23 close the conduit 17 from above and below.

  The conduit 17 has a substantially rectangular shape in a cross section taken along the line II-II, while a stepped side face whose width becomes narrower toward the lower metal layer 21 in the cross section taken along the line III-III Have.

  Further, by laminating the metal layers 21 to 23 in this manner, the evaporator 13, the condenser 14, the vapor pipe 15, and the liquid pipe 16 described above are formed on the laminated body of these metal layers 21 to 23. Be done.

  Next, as shown in FIG. 16 (b), the gas G at a pressure higher than the atmospheric pressure is piped from the inlet 11a (see FIG. 14) while maintaining the laminate of the metal layers 21 to 23 at room temperature. Introduced in 17. As a result, each of the lower metal layer 21 and the upper metal layer 23 is plastically deformed by the pressure P of the gas G, and each of the metal layers 21 and 23 expands to the outside of the conduit 17. As the gas G, in the present embodiment, air with a pressure of 0.5 MPa is employed.

  Moreover, in the cross section along the III-III line, since the width of the conduit 17 is narrowed as approaching the lower metal layer 21, the expansion of the lower metal layer 21 is suppressed.

  Next, as shown in FIG. 17, water is injected as the working fluid C from the inlet 11 a into the conduit 17. Thereafter, the working fluid C is enclosed in the conduit 17 by sealing the inlet 11 a.

  Thus, the loop heat pipe 11 according to the present embodiment is completed.

  According to the method of manufacturing the loop heat pipe 11 according to the present embodiment, the pressure of the gas G is applied to the lower metal layer 21 and the upper metal layer 23 without mechanical processing, and these metal layers 21 and 22 are produced. Can be easily inflated.

Second Example FIGS. 18 to 19 are cross-sectional views of the loop heat pipe 11 according to a second example, which are being manufactured. Also in these figures, as in FIGS. 16 to 17, the cross sections taken along line II-II and line III-III in FIG.

  First, as shown in FIG. 18 (a), the respective metal layers 21 to 23 are joined by diffusion bonding by pressing while heating the respective metal layers 21 to 23 in the same manner as FIG. 16 (a). .

  Next, as shown in FIG. 18 (b), water is injected as the working fluid C from the inlet 11 a (see FIG. 14) into the conduit 17. Thereafter, the working fluid C is enclosed in the conduit 17 by sealing the inlet 11 a.

  Then, as shown in FIG. 19, the working fluid C is heated from the outside of the pipe line 17 to a temperature of about 200 ° C. higher than its boiling point and vaporized. Thus, each of the lower metal layer 21 and the upper metal layer 23 is plastically deformed at the pressure P of the vaporized working fluid C, and each of the metal layers 21 and 23 can be expanded to the outside of the conduit 17. .

  At this time, in the cross section taken along the line III-III, expansion of the lower metal layer 21 is suppressed as in the first example.

  Thus, the loop heat pipe 11 according to the present embodiment is completed.

  According to the method of manufacturing the loop heat pipe 11 according to the present embodiment, the lower metal layer 21 and the upper metal layer 23 are expanded by the pressure of the vaporized working fluid C, so that the metal layer is exclusively used to expand these metal layers. The process of injecting the gas into the conduit 17 is not necessary, and the process can be simplified.

  Next, various modifications of the present embodiment will be described.

(First modification)
FIG. 20 is a cross-sectional view of the loop heat pipe 11 in the first modified example, and corresponds to a cross-sectional view taken along the line II-II in FIG.

  As shown in FIG. 20, in this modification, by setting the thickness of the upper metal layer 23 to about 200 μm, the thickness of the upper metal layer 23 is thicker than the thickness (100 μm) of the lower metal layer 21. Do. Thereby, when the pressure in the conduit 17 is increased in the process of FIG. 16B and FIG. 19, the lower metal layer 21 is easily expanded to the outside by the pressure, but the plastic deformation is difficult. The upper metal layer 23 does not swell easily, and the outer surface 23 x of the upper metal layer 23 can be maintained flat.

  Therefore, the upper metal layer 23 contacts the housing 12 even if there is no space between the upper metal layer 23 and the housing 12 for allowing the upper metal layer 23 to swell. It is possible to selectively include only the lower metal layer 21 while preventing this.

  Although the upper metal layer 23 is thicker than the lower metal layer 21 in the example of FIG. 20, the lower metal layer 21 may be thicker than the upper metal layer 23 in the opposite manner.

  FIG. 21 is a cross-sectional view in this case.

  In this case, since the expansion of the lower metal layer 21 is suppressed and the outer surface 21 x becomes flat, the housing 12 can be provided so as to be under the lower metal layer 21.

(2nd modification)
FIG. 22 is a cross-sectional view of the loop heat pipe 11 in the second modified example, and corresponds to the cross-sectional view along the line II-II in FIG. 3.

  As shown in FIG. 22, the upper metal layer 23 in the present modification has a joint portion 23 a joined to the intermediate layer 22 and a pipe wall portion 23 b facing the pipe line 17. And in this modification, thickness of tube wall part 23b is made thinner than thickness of joined part 23a.

  Thereby, when the pressure in the conduit 17 is increased in the process of FIG. 16 (b) or FIG. 19, the pipe wall portion 23 b can be largely expanded outward by the pressure.

  In order to make the tube wall portion 23b thinner than the bonding portion 23a as described above, the tube wall portion 23b may be wet etched while covering the bonding portion 23a with a resist mask (not shown).

  Moreover, although the pipe wall part 23b of the upper side metal layer 23 was made thin in the example of FIG. 22, you may thin the lower side metal layer 21 conversely to this.

  FIG. 23 is a cross-sectional view in this case.

  In this case, the lower metal layer 21b of the lower metal layer 21 is made thinner by making the thickness of the tube wall 21b facing the pipe 17 smaller than the thickness of the joint 21a joined to the intermediate layer 22. 21 is likely to be greatly expanded toward the outside of the conduit 17.

Second Embodiment
In the first embodiment, at least one of the lower metal layer 21 and the upper metal layer 23 is expanded. Although this can reduce the resistance that the working fluid receives from the conduit 17, there is also a risk that the conduit 17 may rupture during a reliability test on the loop heat pipe 11. As such a reliability test, there is, for example, a thermal test. The cold heat test is a test in which the cooling and heating of the loop heat pipe 11 are repeated, and in the test, the working fluid C repeatedly changes its phase between the liquid phase and the gas phase, and the pipe line 17 Can burst.

  Therefore, in the present embodiment, the risk of rupture of the conduit 17 is reduced as follows.

  FIG. 24A is a cross-sectional view of the steam pipe 15 before the metal layers 21 and 23 are expanded to the outside of the pipe line 17.

  As shown in FIG. 24 (a), each of the metal layers 21 and 23 includes an inner surface 21y facing the conduit 17 and an outer surface 21x facing the inner surface 21y. Have. And in this embodiment, crevices 21w and 23w are formed in each of inner side surfaces 21y and 23y.

  FIG. 24B is a cross section of the steam pipe 15 after the lower metal layer 21 and the upper metal layer 23 are expanded to the outside of the pipe line 17 in the steps of FIG. 16B and FIG. 19 of the first embodiment. FIG.

  In the present embodiment, since the recesses 21w and 23w are formed in each of the lower metal layer 21 and the upper metal layer 23 as described above, each of the metal layers 21 and 23 is easily plastically deformed. It becomes easy to expand 23 outward.

  In addition, since the thickness of each of the metal layers 21 and 23 in the portion where the concave portions 21 w and 23 w are not formed is maintained, the risk of rupture of the metal layers 21 and 23 at the time of expansion can also be reduced.

  In this example, the recesses 21w and 23w are formed in each of the lower metal layer 21 and the upper metal layer 23, but the recesses 21w and 23w are formed in only one of the lower metal layer 21 and the upper metal layer 23 May be

  Further, the size of the recess 21 w is not particularly limited. In this example, the width A of the recess 21 w is about 1 mm, and the distance B between adjacent recesses 21 w is about 1 mm. Moreover, the depth of each recess 21 w is about 30 μm to 60 μm. The width, spacing, and dimensions of the recess 23 w are also the same.

  FIG. 25 is a plan view for explaining the planar shape of the recess 21 w.

  As shown in FIG. 25, the recess 21 w is a striped groove extending in the flow direction of the vapor Cv in plan view. As a result, the recess 21 w functions as a guide groove for guiding the steam Cv along the steam pipe 15, so the flow of the steam Cv in the steam pipe 15 becomes smooth.

  In addition, the recessed part 21w is not formed in the junction part 21a. As a result, the contact area between the bonding portion 21a and the intermediate metal layer 22 (see FIG. 24B) is secured, so that the bonding strength between the bonding portion 21a and the intermediate metal layer 22 can be maintained.

  Further, since the recess 23 w also has the same planar shape as the recess 21 w, the description thereof is omitted.

  The site | part which forms each recessed part 21w and 23w is not limited to the steam pipe 15. As shown in FIG.

  FIG. 26 is a plan view showing a portion R where the concave portions 21 w and 23 w are formed in the loop heat pipe 11.

  As shown in FIG. 26, the portion R extends from the steam pipe 15 to the condenser 14. By forming the recesses 21 w and 23 w in the condenser 14 as described above, the metal layers 21 and 23 in the condenser 14 can be easily expanded while maintaining the strength of the metal layers 21 and 23.

  However, when there is a possibility that the pipe line 17 in the condenser 14 and other parts come in contact with each other, the metal layers 21 and 23 in the condenser 14 do not form the recesses 21 w and 23 w. The channel 17 may not be inflated.

  Next, a method of processing the lower metal layer 21 according to the present embodiment will be described. In addition, since the processing method of the upper side metal layer 23 is the same as this, below, the description is abbreviate | omitted.

  FIGS. 27 (a) to 27 (c) are cross-sectional views for explaining the method of processing the lower metal layer 21 according to the present embodiment.

  First, as shown in FIG. 27A, a metal layer 21z such as a copper layer is prepared. Then, the first resist layer 31 is formed on the inner surface 21y of the metal layer 21z, and the second resist layer 32 is formed on the outer surface 21x of the metal layer 21z. Among these, in the first resist layer 31, a resist opening 31a corresponding to the above-mentioned recess 21w is formed.

  Next, as shown in FIG. 27B, the metal layer 21z is wet-etched from both sides while using the resist layers 31 and 32 as a mask.

  As a result, the recess 21w is formed in the metal layer 21z under the resist opening 31a, and the metal layer 21z in a portion not covered with any of the resist layers 31 and 32 is removed by wet etching.

  Thereafter, as shown in FIG. 27C, the resist layers 31 and 32 are removed to obtain a basic structure of the lower metal layer 21.

  The present embodiment is not limited to the above. Below, various modifications of the present embodiment will be described.

(First modification)
FIG. 28 is a cross-sectional view of a steam pipe 15 according to a first modification.

  In the present modification, recesses 21w and 23w are formed on the outer surfaces 21x and 23x of the metal layers 21 and 23, respectively. Thus, the respective metal layers 21 and 23 can be easily expanded to the outside of the conduit 17 as in the example of FIG. 24B, and the respective metal layers 21 of the portion where the concave portions 21 w and 23 w are not formed. , 23 can be maintained to prevent the rupture of each metal layer 21, 23 during expansion.

  Moreover, since the inner surfaces 21y and 23y of the metal layers 21 and 23 are smooth, the pressure loss of the vapor Cv flowing inside the tube can be reduced.

(2nd modification)
FIG. 29 is an enlarged plan view of the lower metal layer 21 according to the second modification.

  In this example, the concave portions 21 w formed in the inner surface 21 y of the lower metal layer 21 have a lattice shape in plan view. As a result, the lower metal layer 21 is more likely to be plastically deformed as compared with the case where the recess 21 w is formed in a stripe shape as shown in FIG. 25, and it becomes easy to expand the conduit 17.

  In addition, since the planar shape of the recessed part 23w formed in the upper side metal layer 23 is the same as this, the description is abbreviate | omitted.

(Third modification)
FIG. 30 is an enlarged plan view of the lower metal layer 21 according to the third modification.

  In this example, the planar shape of the recess 21 w is circular, and a plurality of recesses 21 w are formed on the inner surface 21 y at intervals. By selectively disposing such a recess 21 w in a portion to be expanded in the lower metal layer 21, it is possible to expand only a necessary portion in the lower metal layer 21.

  In addition, since the planar shape of the recessed part 23w formed in the upper side metal layer 23 is the same as this, the description is abbreviate | omitted.

(4th modification)
FIG. 31 is an enlarged plan view of the lower metal layer 21 according to the fourth modification.

  In this example, the inner surface 21y is formed with a recess 21w having a shape in which three striped grooves extending in the extending direction of the steam pipe 15 and a circular bottomed hole provided between these grooves are combined. Do.

  In addition, since the planar shape of the recessed part 23w formed in the upper side metal layer 23 is the same as this, the description is abbreviate | omitted.

DESCRIPTION OF SYMBOLS 1, 11 ... Loop type heat pipe, 2, 12 ... Housing | casing 3, 3, 13 ... Evaporator, 4, 14 ... Condenser, 5, 15 ... Steam pipe, 6, 16 ... Liquid pipe, 7, 18 ... Heat generation parts 8 metal layer 9, 17 duct, 19 electronic component, 21 lower metal layer, 21a joint portion 21b tube wall portion 21x outer surface 21y inner surface 21w recess portion Reference numeral 22 intermediate metal layer 22a hole 23 upper metal layer 23a joint portion 23b tube wall portion 23x outer surface 23y inner surface 23w concave portion 25 porous body 26 TIM , C ... working fluid, Cv ... steam.

Claims (15)

An intermediate metal layer in which a looped pipeline is formed;
A lower metal layer joined below the intermediate metal layer and blocking the conduit from below;
An upper metal layer joined onto the intermediate metal layer and closing the conduit from above;
A working fluid sealed in the conduit and existing in a liquid or vapor state;
An evaporator provided in the pipe for evaporating the liquid working fluid;
A condenser provided in the pipe line for condensing the vapor;
A pipe between the evaporator and the condenser, in which the steam flows,
The pipe between the evaporator and the condenser, and a liquid pipe through which the working fluid flows;
A loop characterized in that in at least one of the lower metal layer and the upper metal layer in the condenser, the liquid pipe, and a part of any one of the steam pipes, the at least one of the lower metal layer and the upper metal layer is expanded toward the outside of the pipe. Mold heat pipe. The thickness of the upper metal layer is thicker than the lower metal layer,
The loop heat pipe according to claim 1, wherein the outer surface of the upper metal layer is flat. A plurality of the intermediate metal layers are stacked,
The width of the conduit formed in each of the plurality of intermediate metal layers narrows stepwise from the upper metal layer to the lower metal layer,
The loop heat pipe according to claim 1, wherein the lower metal layer expands less than the upper metal layer. The upper metal layer has a joint joined to the intermediate layer, and a pipe wall facing the pipe,
The loop heat pipe according to claim 1, wherein the thickness of the tube wall portion is smaller than the thickness of the joint portion. A porous body for holding the liquid working fluid is provided in the pipe from the middle of the liquid pipe to the evaporator.
At least one of the lower metal layer and the upper metal layer is expanded toward the outside of the pipe line in the pipe line in a portion from the middle part of the liquid pipe to the condenser. The loop type heat pipe according to Item 1. Each of the lower metal layer and the upper metal layer has an inner surface opposite to the conduit and an outer surface opposite to the inner surface,
The loop type heat according to claim 1, wherein a recess is formed in at least one of the lower metal layer and the upper metal layer of the portion corresponding to the steam pipe. pipe.   The loop heat pipe according to claim 6, wherein the recess is a groove extending along the flow direction of the steam.   The loop heat pipe according to claim 6, wherein the recess is circular in a plan view, and a plurality of the recesses are formed at intervals.   The loop heat pipe according to claim 6, wherein the recess is a grid-like groove in plan view. A step of forming each of the evaporator, the condenser, the liquid pipe, and the steam pipe by sequentially laminating and bonding the lower metal layer, the intermediate metal layer in which the looped pipeline is formed, and the upper metal layer. When,
By increasing the pressure inside the pipe, at least one of the lower metal layer and the upper metal layer of the condenser, the liquid pipe, and a part of the steam pipe can be Expanding outwards;
Sealing the working fluid in the conduit;
A method of manufacturing a loop-type heat pipe having: The expanding step comprises
After the step of sealing the working fluid in the conduit, the working fluid is heated and vaporized, and at least one of the lower metal layer and the upper metal layer is expanded by the pressure of the vaporized working fluid. The method for manufacturing a loop heat pipe according to claim 10, which is performed. The expanding step comprises
By introducing a gas having a pressure higher than atmospheric pressure into the pipe and expanding at least one of the lower metal layer and the upper metal layer at the pressure of the gas before the step of sealing the working fluid. The method for manufacturing a loop heat pipe according to claim 10, which is performed.   The method according to claim 11 or 12, wherein a thickness of the upper metal layer is thicker than that of the lower metal layer.   In the step of sequentially laminating and joining the lower metal layer, the intermediate metal layer, and the upper metal layer, the width of the conduit narrows stepwise from the upper metal layer toward the lower metal layer. The method according to claim 10, wherein a plurality of the intermediate layers are laminated and joined together. Each of the lower metal layer and the upper metal layer has an inner surface facing the conduit and an outer surface facing the inner surface,
The method according to claim 10, further comprising the step of forming a recess in at least one of the lower metal layer and the upper metal layer of the portion corresponding to the steam pipe. Manufacturing method of loop type heat pipe.

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