Loop-type heat pipe and method for manufacturing a loop-type heat pipe
The loop heat pipe design with non-overlapping grooves in dual metal layers and a porous body structure addresses the need for thinner heat pipes, achieving efficient heat dissipation in compact electronic devices by vaporizing and condensing a working fluid.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SHINKO ELECTRIC IND CO LTD
- Filing Date
- 2023-01-20
- Publication Date
- 2026-06-01
AI Technical Summary
Existing loop heat pipes are not thin enough for modern electronic devices, particularly in mobile applications like smartphones and tablets, where space is limited.
The loop heat pipe design incorporates a structure with a first and second metal layer, each having blind holes and grooves on their inner surfaces, with a porous body between them, where the grooves of the two layers do not overlap, enhancing capillary action and reducing pressure loss.
This design allows for a thinner heat pipe that efficiently cools heat-generating components by vaporizing and condensing a working fluid, reducing pressure loss and enabling effective heat dissipation in compact electronic devices.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a loop heat pipe and a method for manufacturing a loop heat pipe.
Background Art
[0002] Conventionally, as a device for cooling heat-generating components of semiconductor devices (e.g., CPU, etc.) mounted on electronic devices, a heat pipe that transports heat by utilizing the phase change of a working fluid has been proposed (see, for example, Patent Documents 1 and 2).
[0003] As an example of a heat pipe, there is known a loop heat pipe including an evaporator that vaporizes a working fluid by the heat of a heat-generating component, and a condenser that cools and liquefies the vaporized working fluid, and the evaporator and the condenser are connected by a liquid pipe and a vapor pipe that form a loop-shaped flow path. In the loop heat pipe, the working fluid flows in one direction through the loop-shaped flow path.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0005] By the way, in the above-described loop heat pipe, further thinning is desired.
Means for Solving the Problems
[0006] According to one aspect of the present invention, the present invention comprises an evaporator for vaporizing a working fluid, a condenser for liquefying the working fluid, a liquid pipe connecting the evaporator and the condenser, a steam pipe connecting the evaporator and the condenser, and a loop-shaped flow path through which the working fluid flows, wherein at least one structure of the evaporator, the condenser, the liquid pipe and the steam pipe comprises a first metal layer having a first inner surface and a first outer surface that becomes the outer surface of the structure, a second metal layer having a second inner surface joined to the first inner surface and a second outer surface that becomes the outer surface of the structure, and the first outer surface and the The material comprises a porous body provided between two outer surfaces, the porous body having a plurality of first blind holes provided on the first inner surface, a plurality of second blind holes provided on the second inner surface, a pore formed by the partial communication of the first blind holes and the second blind holes, a first groove provided on the first inner surface and connecting two or more of the first blind holes, and a second groove provided on the second inner surface and connecting two or more of the second blind holes, wherein the first groove and the second groove are provided so as not to overlap each other in a plan view. [Effects of the Invention]
[0007] According to one aspect of the present invention, it has the effect of enabling thinning. [Brief explanation of the drawing]
[0008] [Figure 1] This is a schematic plan view showing a loop-type heat pipe in one embodiment. [Figure 2] This is a schematic plan view showing a portion of a loop-type heat pipe in one embodiment. [Figure 3] This is a schematic cross-sectional view (cross-sectional view along line 3-3 in Figures 2 and 4) showing an evaporator of one embodiment. [Figure 4] This is an enlarged plan view showing a portion of the porous body of an evaporator in one embodiment. [Figure 5] This is a schematic cross-sectional view (cross-sectional view along line 5-5 in Figure 4) showing an evaporator of one embodiment. [Figure 6] This is a schematic cross-sectional view (cross-sectional view along line 6-6 in Figure 4) showing an evaporator of one embodiment. [Figure 7] This is a schematic cross-sectional view (cross-sectional view along line 7-7 in Figure 4) showing an evaporator of one embodiment. [Figure 8] This is a schematic cross-sectional view (section along line 8-8 in Figure 1) showing a steam pipe in one embodiment. [Figure 9] This is a schematic cross-sectional view (cross-sectional view along line 9-9 in Figure 1) showing a condenser of one embodiment. [Figure 10] This is a schematic cross-sectional view (cross-sectional view along line 10-10 in Figure 1) showing a liquid pipe in one embodiment. [Figure 11] (a) and (b) are schematic cross-sectional views illustrating a method for manufacturing a loop-type heat pipe according to one embodiment. [Figure 12] (a) and (b) are schematic cross-sectional views illustrating a method for manufacturing a loop-type heat pipe according to one embodiment. [Figure 13] (a) and (b) are schematic cross-sectional views illustrating a method for manufacturing a loop-type heat pipe according to one embodiment. [Figure 14] (a) and (b) are schematic cross-sectional views illustrating a method for manufacturing a loop-type heat pipe according to one embodiment. [Figure 15] (a) and (b) are schematic cross-sectional views illustrating a method for manufacturing a loop-type heat pipe according to one embodiment. [Figure 16] (a) and (b) are schematic cross-sectional views illustrating a method for manufacturing a loop-type heat pipe according to one embodiment. [Figure 17] This is an enlarged plan view showing a portion of the porous material of the modified evaporator. [Figure 18] This is a schematic cross-sectional view (section 18-18 in Figure 17) showing the modified evaporator. [Figure 19] This is a schematic cross-sectional view (section 19-19 in Figure 17) showing the modified evaporator. [Modes for carrying out the invention]
[0009] One embodiment will be described below with reference to the attached drawings. Note that the attached drawings may, for the sake of convenience, show the characteristic parts enlarged to make the characteristics easier to understand, and the dimensional ratios of each component may be different in each drawing. Also, in cross-sectional views, in order to make the cross-sectional structures of each member easier to understand, the hatching of some members is shown by substituting a satin pattern, and the hatching of some members is omitted. In each drawing, the XYZ axes orthogonal to each other are illustrated. In the following description, for the sake of convenience, the direction extending along the X axis is referred to as the X-axis direction, the direction extending along the Y axis is referred to as the Y-axis direction, and the direction extending along the Z axis is referred to as the Z-axis direction. Note that in this specification, "plan view" means looking at the object from the vertical direction (here, the Z-axis direction) such as in FIG. 3, and "planar shape" means the shape of the object when viewed from the vertical direction such as in FIG. 3. Also, terms such as "first", "second", "third", etc. in this specification are merely used to distinguish objects and do not rank the objects. Also, the expression "at least one" used in this specification means "one or more" of the desired options. As an example, the expression "at least one" used in this specification means "only one option" or "both of the two options" if the number of options is two. As another example, the expression "at least one" used in this specification means "only one option" or "any combination of two or more options" if the number of options is three or more.
[0010] (Overall Structure of Loop Heat Pipe 20) The loop heat pipe 20 shown in FIG. 1 is housed, for example, in a mobile electronic device M1 such as a smartphone or a tablet terminal. The loop heat pipe 20 has an evaporator 21, a vapor pipe 22, a condenser 23, and a liquid pipe 24.
[0011] The evaporator 21 and the condenser 23 are connected by a vapor pipe 22 and a liquid pipe 24. The evaporator 21 has a function of vaporizing the working fluid C to generate vapor Cv. The vapor Cv generated in the evaporator 21 is sent to the condenser 23 via the vapor pipe 22. The condenser 23 has a function of liquefying the vapor Cv of the working fluid C. The liquefied working fluid C is sent to the evaporator 21 via the liquid pipe 24. The evaporator 21, the vapor pipe 22, the condenser 23, and the liquid pipe 24 form a loop-shaped flow path 25 through which the working fluid C or the vapor Cv flows.
[0012] The vapor pipe 22 is formed, for example, in a long tubular body. The liquid pipe 24 is formed, for example, in a long tubular body. In the present embodiment, the vapor pipe 22 and the liquid pipe 24 are, for example, equal in dimension (i.e., length) in the longitudinal direction. Note that the length of the vapor pipe 22 and the length of the liquid pipe 24 may be different from each other. For example, the length of the vapor pipe 22 may be shorter than the length of the liquid pipe 24. Here, the "longitudinal direction" of the evaporator 21, the vapor pipe 22, the condenser 23, and the liquid pipe 24 in this specification is the direction that coincides with the direction in which the working fluid C or the vapor Cv flows in each member (see the arrow in the figure). Also, in this specification, "equal" includes cases where there are slight differences between the comparison targets due to the influence of dimensional tolerances and the like, in addition to cases where they are exactly equal.
[0013] (Configuration of the evaporator 21) The evaporator 21 is fixedly attached in close contact with a heat-generating component (not shown). The working fluid C in the evaporator 21 is vaporized by the heat generated by the heat-generating component, and vapor Cv is generated. Note that a thermal conductive member (TIM: Thermal Interface Material) may be interposed between the evaporator 21 and the heat-generating component. The thermal conductive member reduces the contact thermal resistance between the heat-generating component and the evaporator 21 and smooths the heat conduction from the heat-generating component to the evaporator 21.
[0014] (Configuration of the vapor pipe 22) The steam pipe 22 has, for example, a pair of pipe walls 22w provided on both sides in the width direction perpendicular to the length direction of the steam pipe 22 in a plan view, and a flow path 22r provided between the pair of pipe walls 22w. The flow path 22r communicates with the internal space of the evaporator 21. The flow path 22r is part of a loop-shaped flow path 25. The steam Cv generated in the evaporator 21 is guided to the condenser 23 via the steam pipe 22.
[0015] (Configuration of condenser 23) The condenser 23 includes, for example, a heat dissipation plate 23p with an enlarged surface area for heat dissipation, and a flow path 23r provided inside the heat dissipation plate 23p. The flow path 23r is in communication with the flow path 22r. The flow path 23r is part of a loop-shaped flow path 25. The condenser 23 has tube walls 23w provided on both sides of the flow path 23r in the width direction perpendicular to the length direction in a plan view. Steam Cv introduced through the steam pipe 22 is liquefied in the condenser 23.
[0016] (Configuration of liquid pipe 24) The liquid tube 24 has, for example, a pair of tube walls 24w provided on both sides in the width direction perpendicular to the length direction of the liquid tube 24 in a plan view, and a flow path 24r provided between the pair of tube walls 24w. The flow path 24r communicates with the flow path 23r of the condenser 23 and also communicates with the internal space of the evaporator 21. The flow path 24r is part of a loop-shaped flow path 25.
[0017] The liquid pipe 24 has, for example, a pair of porous bodies 24s and a flow path 28 provided between the pair of porous bodies 24s. Each porous body 24s extends, for example, along the length of the liquid pipe 24 from the condenser 23 to the vicinity of the evaporator 21. Each porous body 24s guides the working fluid C liquefied in the condenser 23 to the evaporator 21 by the capillary force generated within it.
[0018] In the loop-type heat pipe 20, the heat generated by the heat-generating component is transferred to the condenser 23, where it is dissipated. This cools the heat-generating component and suppresses the temperature rise of the heat-generating component.
[0019] Here, it is preferable to use a fluid with a high vapor pressure and large latent heat of vaporization as the working fluid C. By using such a working fluid C, heat-generating components can be efficiently cooled by the latent heat of vaporization. Examples of working fluid C include ammonia, water, Freon, alcohol, acetone, etc.
[0020] (Specific structure of evaporator 21) As shown in Figure 2, the evaporator 21 has, for example, a tube wall 21w and a porous body 21s. The tube wall 21w is provided, for example, at both ends in the width direction (here, the X-axis direction) of the evaporator 21. The tube wall 21w is also provided, for example, at both ends in the length direction (here, the Y-axis direction) of the evaporator 21.
[0021] The porous body 21s has a connecting portion 26 and a plurality of protrusions 27. The connecting portion 26 is provided, for example, in a plan view, in the part of the internal space of the evaporator 21 closest to the liquid pipe 24. The connecting portion 26 is formed to extend, for example, in the width direction (here, the X-axis direction) of the evaporator 21. The surface of the connecting portion 26 on the liquid pipe 24 side is, for example, in contact with the pipe wall 21w, and the remaining part is in contact with the space S1. The surface of the connecting portion 26 on the steam pipe 22 side is, for example, connected to a protrusion 27, and the remaining part is in contact with the space S2. Each protrusion 27, for example, in a plan view, projects from the connecting portion 26 toward the steam pipe 22. Each protrusion 27 is formed to extend, for example, along the length direction (here, the Y-axis direction) of the evaporator 21. The plurality of protrusions 27 are provided, for example, in a plan view, spaced apart from each other along the width direction of the evaporator 21. A space S2 is provided between two adjacent protrusions 27 in the X-axis direction. The end of each protrusion 27 on the steam pipe 22 side is provided away from the pipe wall 21w of the evaporator 21. In other words, a space S2 is provided between the end of each protrusion 27 on the steam pipe 22 side and the pipe wall 21w. In multiple protrusions 27, the ends on the steam pipe 22 side are not connected to each other.
[0022] As described above, the porous body 21s of this embodiment is formed in a comb-like shape with a connecting portion 26 and a plurality of protrusions 27 in a plan view. The number of comb teeth in the porous body 21s can be changed as appropriate. Increasing the contact area between the protrusions 27 and the space S2 makes it easier for the working fluid C to evaporate, thereby reducing pressure loss.
[0023] In the internal space of the evaporator 21, a space S2 is formed in the region where the porous body 21s is not provided. Space S2 is in communication with the flow path 22r of the steam pipe 22. When the working fluid C is introduced into the evaporator 21 from the liquid pipe 24, the working fluid C permeates into the porous body 21s. Inside the evaporator 21, the working fluid C that has permeated into the porous body 21s is vaporized by the heat generated by the heat-generating components fixed to the evaporator 21, and is produced as steam Cv. Then, the steam Cv flows through the space S2 inside the evaporator 21 to the steam pipe 22.
[0024] As shown in Figure 3, the evaporator 21 has a structure in which two layers, a first metal layer 31 and a second metal layer 32, are stacked. In other words, the evaporator 21 is composed only of the first metal layer 31 and the second metal layer 32, which form a pair of outer metal layers.
[0025] Each of the first metal layer 31 and the second metal layer 32 is, for example, a copper (Cu) layer with excellent thermal conductivity. The first metal layer 31 and the second metal layer 32 are directly joined to each other by solid-state bonding such as diffusion bonding, pressure welding, friction welding, or ultrasonic bonding. In the drawings from Figure 3 onward, the first metal layer 31 and the second metal layer 32 are distinguished by solid lines for clarity. For example, when the first metal layer 31 and the second metal layer 32 are integrated by diffusion bonding, the interface between the first metal layer 31 and the second metal layer 32 may disappear, and the boundary may not be clear. Here, solid-state bonding is a method of joining materials by heating them in a solid state without melting them, softening them, and then heating them further to induce plastic deformation. The first metal layer 31 and the second metal layer 32 are not limited to copper layers, but may also be formed from stainless steel layers, aluminum layers, magnesium alloy layers, etc. Furthermore, the materials used for the first metal layer 31 and the second metal layer 32 may be different materials. The thickness of each of the first metal layer 31 and the second metal layer 32 can be, for example, about 50 μm to 200 μm. Note that the thicknesses of the first metal layer 31 and the second metal layer 32 may be different, for example.
[0026] (Composition of the first metal layer 31 and the second metal layer 32) The first metal layer 31 is laminated on the upper surface of the second metal layer 32. The first metal layer 31 has a first inner surface 31A (here, the lower surface) that is joined to the second metal layer 32, and a first outer surface 31B (here, the upper surface) that is provided on the opposite side of the first inner surface 31A in the thickness direction (here, the Z-axis direction) of the first metal layer 31. The first outer surface 31B becomes the outer surface of the evaporator 21. The first metal layer 31 has, for example, a first wall portion 31w, a first porous body 31s, and a first recess 71.
[0027] The second metal layer 32 has a second inner surface 32A (here, the upper surface) that is joined to the first inner surface 31A, and a second outer surface 32B (here, the lower surface) that is provided on the opposite side of the second inner surface 32A in the thickness direction (here, the Z-axis direction) of the second metal layer 32. The second outer surface 32B becomes the outer surface of the evaporator 21. The second metal layer 32 has, for example, a second wall portion 32w, a second porous body 32s, and a second recess 72. The second wall portion 32w is provided in a position that overlaps with the first wall portion 31w in a plan view. The second porous body 32s is provided in a position that partially overlaps with the first porous body 31s in a plan view. The second recess 72 is provided in a position that overlaps with the first recess 71 in a plan view.
[0028] The tube wall 21w is composed of a first wall portion 31w of the first metal layer 31 and a second wall portion 32w of the second metal layer 32. In the tube wall 21w, the first inner surface 31A of the first wall portion 31w and the second inner surface 32A of the second wall portion 32w are joined to each other. No holes or grooves are formed in either the first wall portion 31w or the second wall portion 32w. The porous body 21s is composed of a first porous body 31s of the first metal layer 31 and a second porous body 32s of the second metal layer 32. The porous body 21s is provided between the first outer surface 31B and the second outer surface 32B. The space S2 provided inside the evaporator 21 is composed of a first recess 71 of the first metal layer 31 and a second recess 72 of the second metal layer 32.
[0029] (Specific composition of porous body 21s) As shown in Figure 4, the first porous body 31s has a plurality of first blind holes 41 and a first groove 42 that connects two or more of the first blind holes 41. The second porous body 32s has a plurality of second blind holes 51 and a second groove 52 that connects two or more of the second blind holes 51. The porous body 21s has pores 61 formed by the partial connection of the first blind holes 41 and the second blind holes 51. Figure 4 is an enlarged plan view of a part of the porous body 21s, specifically the part enclosed by the dashed line in Figure 2. Also, for convenience, in Figure 4, the first blind holes 41 and the first groove 42 provided in the first metal layer 31 are shown with solid lines, and the second blind holes 51 and the second groove 52 provided in the second metal layer 32 are shown with dashed lines.
[0030] As shown in Figure 5, the first blind hole 41 is formed to be recessed from the first inner surface 31A of the first metal layer 31 to the center of the first metal layer 31 in the thickness direction. The depth 41D of the first blind hole 41 can be, for example, about 20 μm to 100 μm. The first groove 42 is formed to be recessed from the first inner surface 31A of the first metal layer 31 toward the center of the first metal layer 31 in the thickness direction. The depth 42D of the first groove 42 is shallower than the depth 41D of the first blind hole 41. Preferably, the depth 42D of the first groove 42 is in the range of 0.5 times or more and less than 0.8 times the depth 41D of the first blind hole 41. Here, if the depth 42D of the first groove 42 is less than 0.5 times the depth 41D of the first bottomed hole 41, the first groove 42 will collapse when the first metal layer 31 and the second metal layer 32 are joined, and there is a high possibility that the first groove 42 will cease to function as a path for the working fluid C. Also, if the depth 42D of the first groove 42 is 0.8 times or more the depth 41D of the first bottomed hole 41, the capillary force generated in the first groove 42 will decrease. The depth 42D of the first groove 42 can be, for example, about 10 μm to 70 μm.
[0031] As shown in Figure 6, the second blind hole 51 is formed to be recessed from the second inner surface 32A of the second metal layer 32 towards the center in the thickness direction of the second metal layer 32. The depth 51D of the second blind hole 51 can be, for example, about 20 μm to 100 μm. The second groove 52 is formed to be recessed from the second inner surface 32A of the second metal layer 32 towards the center in the thickness direction of the second metal layer 32. The depth 52D of the second groove 52 is shallower than the depth 51D of the second blind hole 51. Preferably, the depth 52D of the second groove 52 is in the range of 0.5 times or more and 0.8 times or less the depth 51D of the second blind hole 51. Here, if the depth 52D of the second groove 52 is less than 0.5 times the depth 51D of the second bottomed hole 51, the second groove 52 will collapse when the first metal layer 31 and the second metal layer 32 are joined, and there is a high possibility that the second groove 52 will cease to function as a path for the working fluid C. Also, if the depth 52D of the second groove 52 is 0.8 times or more the depth 51D of the second bottomed hole 51, the capillary force generated in the second groove 52 will decrease. The depth 52D of the second groove 52 can be, for example, about 10 μm to 70 μm.
[0032] As shown in Figure 3, the inner surface of the first blind hole 41 is formed in a shape that is continuous in an arc from the opening side, i.e., the first inner surface 31A side of the first metal layer 31, to the bottom side. The inner surface of the second blind hole 51 is formed in a shape that is continuous in an arc from the opening side, i.e., the second inner surface 32A side of the second metal layer 32, to the bottom side. In cross-sectional view, the inner surfaces of the first blind hole 41 and the second blind hole 51 are formed as curved surfaces that are curved in an arc. In cross-sectional view, the bottom surfaces of the first blind hole 41 and the second blind hole 51 are formed as curved surfaces that are curved in an arc. The bottom surface of the first blind hole 41 is formed in a shape that is continuous with the inner surface of the first blind hole 41. The radius of curvature of the bottom surface of the first blind hole 41 may be equal to the radius of curvature of the inner surface of the first blind hole 41, or it may be different from the radius of curvature of the inner surface of the first blind hole 41. The bottom surface of the second blind hole 51 is formed, for example, continuously with the inner surface of the second blind hole 51. The radius of curvature of the bottom surface of the second blind hole 51 may be equal to the radius of curvature of the inner surface of the second blind hole 51, or it may be different from the radius of curvature of the inner surface of the second blind hole 51.
[0033] The inner surfaces of the first and second blind holes 41 and 51 in this embodiment are formed in a concave shape with a cross-sectional shape of a semicircle or semiellipse. Here, in this specification, "semicircle" includes not only a semicircle obtained by bisecting a perfect circle, but also, for example, shapes with an arc longer or shorter than a semicircle obtained by bisecting a perfect circle. Similarly, in this specification, "semiellipse" includes not only a semiellipse obtained by bisecting an ellipse, but also, for example, shapes with an arc longer or shorter than a semiellipse obtained by bisecting an ellipse. The inner surfaces of the first and second blind holes 41 and 51 may be tapered, widening from the bottom side towards the opening side. Alternatively, the bottom surface of the first blind hole 41 may be formed in a plane parallel to the first inner surface 31A of the first metal layer 31, and the inner surface of the first blind hole 41 may be formed to extend perpendicularly to the bottom surface. The bottom surface of the second blind hole 51 may be formed as a plane parallel to the second inner surface 32A of the second metal layer 32, and the inner surface of the second blind hole 51 may be formed to extend perpendicularly to the bottom surface.
[0034] The planar shapes of the first and second blind holes 41 and 51 can be any shape and size. The planar shapes of the first and second blind holes 41 and 51 can be formed, for example, as circles, ellipses, or polygons. The planar shapes of the first and second blind holes 41 and 51 can be the same or different. As shown in Figure 4, the planar shapes of the first and second blind holes 41 and 51 in this embodiment are formed in a circular shape. The diameters of the first and second blind holes 41 and 51 can be, for example, about 100 μm to 400 μm.
[0035] The multiple first bottomed holes 41 are arranged, for example, in a grid or matrix in a plan view. The multiple first bottomed holes 41 are arranged, for example, along the X-axis direction (first direction) and along the Y-axis direction (second direction). For example, the multiple first bottomed holes 41 are spaced apart from each other along the X-axis direction and spaced apart from each other along the Y-axis direction. Two adjacent first bottomed holes 41 in the X-axis direction are, for example, located at the same position in the Y-axis direction. Two adjacent first bottomed holes 41 in the Y-axis direction are, for example, located at the same position in the X-axis direction. Here, the first direction in this embodiment coincides with the width direction of the evaporator 21 and extends along a direction intersecting the direction in which the working fluid C flows. The second direction in this embodiment coincides with the length direction of the evaporator 21 and extends along the direction in which the working fluid C flows.
[0036] Multiple second blind holes 51 are arranged in a grid or matrix pattern in a plan view, for example. Multiple second blind holes 51 are arranged in a row along the X-axis direction (first direction) and along the Y-axis direction. For example, multiple second blind holes 51 are provided spaced apart from each other along the X-axis direction and also spaced apart from each other along the Y-axis direction. Two adjacent second blind holes 51 in the X-axis direction are provided at the same position in the Y-axis direction, for example. Two adjacent second blind holes 51 in the Y-axis direction are provided at the same position in the X-axis direction, for example. In addition, each second blind hole 51 is provided at a position offset from the first blind hole 41 in the Y-axis direction, for example. Each second blind hole 51 is provided at the same position as the first blind hole 41 in the X-axis direction, for example.
[0037] The first blind hole 41 and the second blind hole 51 partially overlap each other in a plan view. For example, the Y-axis end of the first blind hole 41 and the Y-axis end of the second blind hole 51 overlap each other in a plan view. As shown in Figures 3 and 4, in the portion where the first blind hole 41 and the second blind hole 51 overlap in a plan view, the first blind hole 41 and the second blind hole 51 are partially connected to form a pore 61.
[0038] As shown in Figure 5, the inner surface of the first groove 42 is formed in a shape similar to, for example, the inner surface of the first blind hole 41. As shown in Figure 6, the inner surface of the second groove 52 is formed in a shape similar to, for example, the inner surface of the second blind hole 51.
[0039] As shown in Figure 7, the inner surfaces of the first groove 42 and the second groove 52 in this embodiment are formed in a concave shape with a semicircular or semielliptical cross-sectional shape. Alternatively, the inner surfaces of the first groove 42 and the second groove 52 may be tapered, widening from the bottom side towards the opening side. Furthermore, the bottom surface of the first groove 42 may be formed in a plane parallel to the first inner surface 31A of the first metal layer 31, and the inner surface of the first groove 42 may be formed to extend perpendicularly to the bottom surface. Similarly, the bottom surface of the second groove 52 may be formed in a plane parallel to the second inner surface 32A of the second metal layer 32, and the inner surface of the second groove 52 may be formed to extend perpendicularly to the bottom surface.
[0040] As shown in Figure 4, each first groove 42 is formed to connect, for example, two adjacent first bottomed holes 41 in the X-axis direction. One end of each first groove 42 is connected to one of the two adjacent first bottomed holes 41, and the other end of each first groove 42 is connected to the other first bottomed hole 41. Each second groove 52 is formed to connect, for example, two adjacent second bottomed holes 51 in the X-axis direction. One end of each second groove 52 is connected to one of the two adjacent second bottomed holes 51, and the other end of each second groove 52 is connected to the other second bottomed hole 51.
[0041] The planar shapes of the first groove 42 and the second groove 52 can be any shape and size. The planar shape of the first groove 42 can be any shape and size, for example, as long as it has a structure that allows two or more first bottomed holes 41 to communicate with each other. The planar shape of the second groove 52 can be any shape and size, for example, as long as it has a structure that allows two or more second bottomed holes 51 to communicate with each other. The planar shapes of the first groove 42 and the second groove 52 may be the same or different. In this embodiment, the planar shapes of the first groove 42 and the second groove 52 are formed in a rectangular shape. The planar shapes of the first groove 42 and the second groove 52 are formed in a rectangular shape in the XY plane, having a predetermined width in the Y-axis direction and extending along the X-axis direction. The width of the first groove 42 is, for example, smaller than the width (here, diameter) of the first bottomed hole 41. In other words, the length of the first groove 42 along the Y-axis is smaller than the length of the first bottomed hole 41 along the Y-axis. The width of the second groove 52 is smaller than, for example, the width (here, diameter) of the second bottomed hole 51. In other words, the length of the second groove 52 along the Y-axis is smaller than the length of the second bottomed hole 51 along the Y-axis. The widths of the first groove 42 and the second groove 52 can be, for example, about 50 μm to 100 μm.
[0042] Each first groove 42 extends linearly, for example, along the X-axis direction (first direction). Multiple first grooves 42 are formed to extend parallel to each other. Each second groove 52 extends linearly, for example, along the X-axis direction (first direction). Multiple second grooves 52 are formed to extend parallel to each other, for example. Each second groove 52 is formed to extend parallel to each first groove 42, for example.
[0043] The first groove 42 and the second groove 52 are arranged so as not to overlap in a plan view. The first groove 42 and the second groove 52 are formed so as not to intersect in a plan view. In other words, the porous body 21s does not have any region where the first groove 42 and the second groove 52 overlap in a plan view. To put it another way, in the porous body 21s, the first groove 42 and the second groove 52 are formed so as not to be in direct communication with each other.
[0044] The first groove 42 is provided, for example, so as not to overlap with the second bottomed hole 51 in a plan view. That is, the first groove 42 is formed so as not to communicate directly with the second bottomed hole 51. The second groove 52 is provided, for example, so as not to overlap with the first bottomed hole 41 in a plan view. That is, the first groove 42 is formed so as not to communicate directly with the second bottomed hole 51.
[0045] Only the first groove 42 is provided on the first inner surface 31A and the second inner surface 32A between two adjacent first bottomed holes 41 in the X-axis direction. In other words, no recesses other than the first groove 42 are formed on the first inner surface 31A and the second inner surface 32A between two adjacent first bottomed holes 41 in the X-axis direction, i.e., no recesses such as the second bottomed hole 51 and the second groove 52 are formed.
[0046] Only the second groove 52 is provided on the first inner surface 31A and the second inner surface 32A between two adjacent second bottomed holes 51 in the X-axis direction. In other words, no recesses other than the second groove 52 are formed on the first inner surface 31A and the second inner surface 32A between two adjacent second bottomed holes 51 in the X-axis direction, i.e., no recesses such as the first bottomed hole 41 and the first groove 42 are formed.
[0047] In the first inner surface 31A extending in the Y-axis direction between two adjacent rows of first bottomed holes 41 in the X-axis direction, only the first groove 42 is formed. In other words, in the first inner surface 31A extending in the Y-axis direction between two adjacent rows of first bottomed holes 41 in the X-axis direction, no recesses other than the first groove 42 are formed. That is, in the first inner surface 31A extending in the Y-axis direction between two adjacent rows of first bottomed holes 41 in the X-axis direction, the portion other than the first groove 42 is formed as a solid plane. Furthermore, in the second inner surface 32A extending in the Y-axis direction between two adjacent rows of second bottomed holes 51 in the X-axis direction, only the second groove 52 is formed. In other words, in the second inner surface 32A extending in the Y-axis direction between two adjacent rows of second bottomed holes 51 in the X-axis direction, the portion other than the second groove 52 is formed as a solid plane. As shown in Figure 7, in the portion between two adjacent rows of first bottomed holes 41 (see Figure 4) in the X-axis direction, where the first groove 42 and the second groove 52 are not formed, the first inner surface 31A and the second inner surface 32A are directly joined to each other.
[0048] As shown in Figure 5, in the first cross-section obtained by cutting the porous body 21s with the XZ plane along the X-axis direction and passing through the center of the width direction of the first groove 42, the first bottomed hole 41 and the first groove 42 are continuously formed along the X-axis direction on the first inner surface 31A of the first metal layer 31. Also, in the first cross-section, the entire surface of the second inner surface 32A of the second metal layer 32 is formed as a solid plane. In other words, in the first cross-section, the second bottomed hole 51 and the second groove 52 (see Figure 4) are not formed on the second inner surface 32A of the second metal layer 32. Thus, in the region overlapping with the first groove 42 in the X-axis direction, only the first bottomed hole 41 is provided, and the second bottomed hole 51 and the second groove 52 (see Figure 4) are not provided. Furthermore, the boundary portion 43 between the first bottomed hole 41 and the first groove portion 42 is not in contact with the second inner surface 32A of the second metal layer 32. A space is provided between the boundary portion 43 and the second inner surface 32A of the second metal layer 32.
[0049] As shown in Figure 6, in the second cross-section obtained by cutting the porous body 21s with the XZ plane along the X-axis direction and passing through the center of the width direction of the second groove 52, the second bottomed hole 51 and the second groove 52 are continuously formed along the X-axis direction on the second inner surface 32A of the second metal layer 32. Also, in the second cross-section, the entire surface of the first inner surface 31A of the first metal layer 31 is formed as a solid plane. In other words, in the second cross-section, the first bottomed hole 41 and the first groove 42 are not formed on the first inner surface 31A of the first metal layer 31. Thus, in the region overlapping with the second groove 52 in the X-axis direction, only the second bottomed hole 51 is provided, and the first bottomed hole 41 and the first groove 42 (see Figure 4) are not provided. Furthermore, the boundary 53 between the second bottomed hole 51 and the second groove 52 is not in contact with the first inner surface 31A of the first metal layer 31. A space is provided between the boundary portion 53 and the first inner surface 31A of the first metal layer 31.
[0050] As shown in Figure 4, the first bottomed hole 41, the first groove 42, the second bottomed hole 51, the second groove 52, and the pore 61 are all in communication with each other. The space formed by the communication of these three elements extends three-dimensionally. The flow channels of the porous body 21s, including the first bottomed hole 41, the first groove 42, the second bottomed hole 51, the second groove 52, and the pore 61, function as flow channels for the liquid-phase working fluid C (see Figure 1).
[0051] (Specific configuration of space S2) As shown in Figure 3, the space S2 is formed by the first recess 71 of the first metal layer 31 and the second recess 72 of the second metal layer 32 communicating with each other. For example, the first recess 71 and the second recess 72 are formed to completely overlap in a plan view. That is, the entirety of the first recess 71 is formed to overlap the entirety of the second recess 72 in a plan view.
[0052] The first recess 71 is formed so as to extend from the first inner surface 31A of the first metal layer 31 to the central part in the thickness direction of the first metal layer 31. The depth 71D of the first recess 71 is, for example, deeper than the depth 41D of the first bottomed hole 41. The depth 71D of the first recess 71 is, for example, in the range of 1.1 times or more and 1.3 times or less than the depth 41D of the first bottomed hole 41. The depth 71D of the first recess 71 can be, for example, about 25 μm to 130 μm.
[0053] The second recess 72 is formed so as to be recessed from the second inner surface 32A of the second metal layer 32 to the central part in the thickness direction of the second metal layer 32. The depth 72D of the second recess 72 is, for example, deeper than the depth 51D of the second bottomed hole 51. The depth 72D of the second recess 72 is, for example, in the range of 1.1 times to 1.3 times the depth 51D of the second bottomed hole 51. The depth 72D of the second recess 72 can be, for example, about 25 μm to 130 μm.
[0054] The inner surfaces of the first recess 71 and the second recess 72 can be any shape. In this embodiment, the inner surfaces of the first recess 71 and the second recess 72 are formed as concave shapes with a rectangular cross-section. The inner surfaces of the first recess 71 and the second recess 72 may be tapered, widening from the bottom side towards the opening side. Alternatively, the inner surfaces of the first recess 71 and the second recess 72 may be concave shapes with a semicircular or semielliptical cross-section.
[0055] The space S2 is in communication with, for example, the flow channels of the porous body 21s. For example, the first recess 71 is in communication with the first bottomed hole 41 or the first groove 42 (see Figure 4). For example, the second recess 72 is in communication with the second bottomed hole 51 or the second groove 52 (see Figure 4). The first groove 42 (see Figure 4) that is in communication with the first recess 71 is formed to connect the first bottomed hole 41 and the first recess 71. The second groove 52 (see Figure 4) that is in communication with the second recess 72 is formed to connect the second bottomed hole 51 and the second recess 72.
[0056] (Configuration of steam pipe 22) As shown in Figure 8, the steam pipe 22, like the evaporator 21 (see Figure 3), is formed by stacking two layers: a first metal layer 31 and a second metal layer 32. In the steam pipe 22, a flow path 22r is formed by the communication between a first recess 71 provided on the first inner surface 31A of the first metal layer 31 and a second recess 72 provided on the second inner surface 32A of the second metal layer 32. The steam pipe 22 has a pair of pipe walls 22w provided on both sides in the width direction (here, the Y-axis direction) perpendicular to the length direction (here, the X-axis direction) of the steam pipe 22. No holes or grooves are formed in each pipe wall 22w, for example. The flow path 22r is provided between the pair of pipe walls 22w. In Figure 8, for convenience, the area of the pipe wall 22w is shown with a dashed line.
[0057] (Configuration of condenser 23) As shown in Figure 9, the condenser 23, like the evaporator 21 (see Figure 3), is formed by stacking two layers: a first metal layer 31 and a second metal layer 32. In the condenser 23, a flow path 23r is formed by the communication between a first recess 71 provided on the first inner surface 31A of the first metal layer 31 and a second recess 72 provided on the second inner surface 32A of the second metal layer 32. The condenser 23 has a pair of tube walls 23w provided on both sides in the width direction (here, the X-axis direction) perpendicular to the length direction (here, the Y-axis direction) of the condenser 23. No holes or grooves are formed in each tube wall 23w, for example. The flow path 23r is provided between the pair of tube walls 23w. In Figure 9, for convenience, the region of the tube wall 23w is shown with a dashed line.
[0058] (Configuration of liquid pipe 24) As shown in Figure 10, the liquid tube 24, like the evaporator 21 (see Figure 3), is formed by stacking two layers: a first metal layer 31 and a second metal layer 32. The liquid tube 24 has a pair of tube walls 24w provided at both ends in the width direction (here, the Y-axis direction), a flow path 28 provided between the pair of tube walls 24w, and a pair of porous bodies 24s provided on both sides of the flow path 28 in the width direction of the liquid tube 24. In the liquid tube 24, the flow path 28 is formed by the communication between a first recess 71 provided on the first inner surface 31A of the first metal layer 31 and a second recess 72 provided on the second inner surface 32A of the second metal layer 32. By providing the flow path 28 in the liquid tube 24, the amount of working fluid C stored in the liquid tube 24 can be increased. In Figure 10, for convenience, the region of the tube wall 24w and the region of the porous body 24s are shown with dashed lines.
[0059] Each porous body 24s is formed integrally with, for example, the pipe wall 24w. Each porous body 24s has a structure similar to, for example, the porous body 21s shown in Figures 3 to 7. Each porous body 24s has a first bottomed hole 41 provided in the first inner surface 31A of the first metal layer 31, a second bottomed hole 51 provided in the second inner surface 32A of the second metal layer 32, and a pore 61 formed by the partial communication of the first bottomed hole 41 and the second bottomed hole 51. Although not shown in the figures, each porous body 24s has a first groove 42 (see Figure 5) and a second groove 52 (see Figure 5). The flow channels of each porous body 24s (i.e., the first bottomed hole 41, the first groove 42, the second bottomed hole 51, the second groove 52, and the pore 61) function as flow channels 24r through which the liquid-phase working fluid C (see Figure 1) flows. In the liquid pipe 24 of this embodiment, the flow path 24r is formed by the flow paths and flow paths 28 of each porous body 24s.
[0060] The liquid pipe 24 is provided with an inlet for injecting the working fluid C (see Figure 1), although this is not shown in the diagram. However, the inlet is sealed by a sealing member, and the loop-type heat pipe 20 is kept airtight.
[0061] (Manufacturing method for loop-type heat pipe 20) Next, the manufacturing method of the loop-type heat pipe 20 will be described with reference to Figures 11 to 16. In each of Figures 11 to 16, (a) shows the cross-sectional structure at the position corresponding to line 3-3 in Figure 4, and (b) shows the cross-sectional structure at the position corresponding to line 7-7 in Figure 4. In each of Figures 11 to 16, although (a) and (b) are at different cutting positions, (a) and (b) represent processes that are performed simultaneously.
[0062] First, in the process shown in Figures 11(a) and 11(b), a flat metal sheet 80 is prepared. The metal sheet 80 is the component that will ultimately become the first metal layer 31 (see Figure 3). The metal sheet 80 has a first inner surface 31A and a first outer surface 31B. The metal sheet 80 is made of, for example, copper, stainless steel, aluminum, magnesium alloy, etc. The thickness of the metal sheet 80 can be, for example, about 50 μm to 200 μm.
[0063] Next, a first resist layer 81 is formed on the first inner surface 31A of the metal sheet 80, and a second resist layer 82 is formed on the first outer surface 31B of the metal sheet 80. The first resist layer 81 is formed to cover the entire surface of the first inner surface 31A of the metal sheet 80. The second resist layer 82 is formed to cover the entire surface of the first outer surface 31B of the metal sheet 80. For example, a photosensitive dry film resist can be used as the first resist layer 81 and the second resist layer 82.
[0064] Next, in the process shown in Figures 12(a) and 12(b), the first resist layer 81 is patterned to form openings 81X, 81Y, and 81Z in the first resist layer 81 that selectively expose the first inner surface 31A of the metal sheet 80. For example, the first resist layer 81 is exposed and developed to form openings 81X, 81Y, and 81Z in the first resist layer 81. The opening 81X shown in Figure 12(a) is formed to correspond to the first bottomed hole 41 shown in Figure 3. The opening 81Y shown in Figure 12(b) is formed to correspond to the first groove 42 shown in Figure 7. The opening 81Z shown in Figure 12(a) is formed to correspond to the first recess 71 shown in Figure 3. Here, the width of opening 81Y is formed to be smaller than the width of opening 81X. Also, the width of opening 81X is formed to be smaller than the width of opening 81Z. Note that the openings 81X, 81Y, and 81Z are formed simultaneously in the same process, for example.
[0065] Next, in the steps shown in Figures 13(a) and 13(b), the metal sheet 80 exposed in the openings 81X, 81Y, and 81Z is etched from the first inner surface 31A side of the metal sheet 80. This simultaneously forms a first bottomed hole 41, a first groove 42, and a first recess 71 on the first inner surface 31A of the metal sheet 80. Specifically, as shown in Figure 13(a), the first bottomed hole 41 is formed by etching the metal sheet 80 exposed from the opening 81X from the first inner surface 31A side. As shown in Figure 13(b), the first groove 42 is formed by etching the metal sheet 80 exposed from the opening 81Y from the first inner surface 31A side. As shown in Figure 13(a), the first recess 71 is formed by etching the metal sheet 80 exposed from the opening 81Z from the first inner surface 31A side. These first bottomed holes 41, first grooves 42, and first recesses 71 can be formed, for example, by wet etching the metal sheet 80 using the first resist layer 81 and the second resist layer 82 as etching masks. When copper is used as the material for the metal sheet 80, an aqueous solution of ferric chloride or an aqueous solution of cupric chloride can be used as the etching solution.
[0066] Next, the first resist layer 81 and the second resist layer 82 are peeled off with a stripping solution. As a result, as shown in Figures 14(a) and 14(b), a first metal layer 31 having a first bottomed hole 41, a first groove 42, and a first recess 71 can be formed on the first inner surface 31A.
[0067] Next, in the steps shown in Figures 15(a) and 15(b), a second metal layer 32 having a second bottomed hole 51, a second groove 52, and a second recess 72 is formed on the second inner surface 32A in the same manner as in the steps shown in Figures 11 to 14. Then, the first metal layer 31 is placed above the second metal layer 32 so that the first inner surface 31A and the second inner surface 32A face each other.
[0068] Next, in the process shown in Figures 16(a) and 16(b), the first metal layer 31 and the second metal layer 32, which have been stacked while being heated to a predetermined temperature (for example, about 900°C), are pressed together to join the first metal layer 31 and the second metal layer 32 by solid-state bonding. At this time, the first inner surface 31A of the first porous body 31s, in which the first bottomed hole 41 and the first groove 42 are not formed, and the second inner surface 32A of the second porous body 32s, in which the second bottomed hole 51 and the second groove 52 are not formed, are directly joined together.
[0069] Through the process described above, a structure is formed in which the first metal layer 31 and the second metal layer 32 are laminated. Then, a loop-type heat pipe 20 having an evaporator 21, a steam pipe 22, a condenser 23, and a liquid pipe 24 as shown in Figure 1 is formed. After that, for example, the liquid pipe 24 is evacuated using a vacuum pump or the like, and then working fluid C is injected into the liquid pipe 24 from an inlet (not shown), and then the inlet is sealed.
[0070] Next, the effects and advantages of this embodiment will be explained. (1) The loop-type heat pipe 20 is formed by only two metal layers, the first metal layer 31 and the second metal layer 32. This makes the loop-type heat pipe 20 thinner compared to when three or more metal layers are laminated. Also, since the amount of metal layers used can be reduced compared to when three or more metal layers are laminated, the manufacturing cost of the loop-type heat pipe 20 can be reduced.
[0071] (2) However, when three or more metal layers are joined together, variations may occur in the bonding state between each metal layer. In contrast, the loop-type heat pipe 20 of this embodiment is composed of only two metal layers, namely the first metal layer 31 and the second metal layer 32, so the stability of the bonding between the first metal layer 31 and the second metal layer 32 can be improved.
[0072] (3) A first bottomed hole 41 and a first groove 42 are formed on the first inner surface 31A of the first metal layer 31, and a second bottomed hole 51 and a second groove 52 are formed on the second inner surface 32A of the second metal layer 32. Furthermore, a pore 61 is formed by partially connecting the first bottomed hole 41 and the second bottomed hole 51. As a result, a three-dimensional flow channel that functions as a porous body 21s can be formed using only the outer metal layers, the first metal layer 31 and the second metal layer 32, without the need for an inner metal layer. The capillary force generated in this porous body 21s allows the liquefied working fluid C to be moved suitably in three dimensions.
[0073] (4) The first groove 42 and the second groove 52 are provided so as not to overlap each other in a plan view. With this configuration, by preventing the first groove 42 and the second groove 52 from overlapping, a large solid area can be secured where the first metal layer 31 and the second metal layer 32 are joined, that is, a solid area where the first groove 42 and the second groove 52 are not formed. As a result, a large joining area can be secured between the first metal layer 31 and the second metal layer 32, thereby improving the joining strength between the first metal layer 31 and the second metal layer 32.
[0074] (5) When the first groove 42 and the second groove 52 are formed to overlap each other in a plan view, they are formed to intersect in a plan view. In this case, in order to intersect the first groove 42 and the second groove 52, for example, the first groove 42 is formed to cross the region between adjacent second bottomed holes 51 in the X-axis direction. In this case, the proportion of the first groove 42 on the first inner surface 31A becomes larger, and the solid area on the first inner surface 31A becomes smaller. As a result, the bonding area between the first metal layer 31 and the second metal layer 32 becomes smaller. In particular, the solid area tends to become smaller in the region between adjacent second bottomed holes 51 in the X-axis direction. Another structure is formed in which the second groove 52 crosses the region between adjacent first bottomed holes 41 in the X-axis direction. In this case, the proportion occupied by the second groove 52 on the second inner surface 32A increases, and the solid area on the second inner surface 32A decreases. As a result, the bonding area between the first metal layer 31 and the second metal layer 32 decreases. In particular, the solid area tends to decrease in the region between adjacent first bottomed holes 41 in the X-axis direction.
[0075] In contrast, in the porous body 21s of this embodiment, a first groove 42 extending along the X-axis is provided for a plurality of first bottomed holes 41 arranged in a manner that is aligned along the X-axis and along the Y-axis. Furthermore, a second groove 52 extending along the X-axis is provided for a plurality of second bottomed holes 51 arranged in a manner that is aligned along the X-axis and along the Y-axis. In this configuration, the first groove 42 is not formed to cross the region between adjacent second bottomed holes 51 in the X-axis direction, and the second groove 52 is not formed to cross the region between adjacent first bottomed holes 41 in the X-axis direction. Therefore, it is possible to suitably suppress the reduction of the solid area on the first inner surface 31A and the second inner surface 32A in the region between adjacent first bottomed holes 41 in the X-axis direction and the region between adjacent second bottomed holes 51 in the X-axis direction. This allows for a wider solid area to be secured where the first metal layer 31 and the second metal layer 32 are joined together, thereby ensuring a larger bonding area between the first metal layer 31 and the second metal layer 32. As a result, the bonding strength between the first metal layer 31 and the second metal layer 32 can be effectively improved.
[0076] (6) The first bottomed holes 41 and the second bottomed holes 51 are arranged alternately along the Y-axis direction, which is the direction in which the working fluid C flows. The Y-axis end of the first bottomed hole 41 is arranged to partially overlap with the second bottomed hole 51 in a plan view. As a result, the working fluid C can be suitably moved in the desired direction by the flow path formed by the first bottomed holes 41, the second bottomed holes 51 and the pores 61 arranged along the Y-axis direction.
[0077] (7) The first bottomed hole 41 is formed deeper than the first groove 42, and the second bottomed hole 51 is formed deeper than the second groove 52. In other words, the first groove 42 is formed shallower than the first bottomed hole 41, and the second groove 52 is formed shallower than the second bottomed hole 51. Furthermore, the width of the first groove 42 is formed smaller than the width of the first bottomed hole 41, and the width of the second groove 52 is formed smaller than the width of the second bottomed hole 51. As a result, the capillary force generated in the first groove 42 and the second groove 52 can be increased, so that the liquid working fluid C can be moved suitably in three dimensions within the flow path of the porous body 21s.
[0078] (8) However, if the depths 42D, 52D of the first groove 42 and the second groove 52 are shallow, there is a high possibility that the first groove 42 and the second groove 52 will collapse when joining the first metal layer 31 and the second metal layer 32. If the first groove 42 and the second groove 52 collapse, adjacent first blind holes 41 and adjacent second blind holes 51 will not be able to communicate with each other. In contrast, in this embodiment, the depth 42D of the first groove 42 is set to a depth in the range of 0.5 times or more and less than 0.8 times the depth 41D of the first blind hole 41, and the depth 52D of the second groove 52 is set to a depth in the range of 0.5 times or more and less than 0.8 times the depth 51D of the second blind hole 51. In other words, the first groove 42 and the second groove 52 are formed to be shallower than the first and second bottomed holes 41 and 51, but to a certain depth. This configuration allows for increased capillary force in the first groove 42 and the second groove 52, while effectively suppressing the collapse of the first groove 42 and the second groove 52 when joining the first metal layer 31 and the second metal layer 32. As a result, when the first metal layer 31 and the second metal layer 32 are joined, the first groove 42 connecting adjacent first bottomed holes 41 and the second groove 52 connecting adjacent second bottomed holes 51 can be effectively maintained.
[0079] (9) A first recess 71 is formed on the first inner surface 31A of the first metal layer 31, and a second recess 72 is formed on the second inner surface 32A of the second metal layer 32. Furthermore, by connecting the first recess 71 and the second recess 72, a space S2 is formed to which the vaporized working fluid C (i.e., vapor Cv) moves. As a result, a space S2 that serves as a space for the movement of the gaseous working fluid C can be formed using only the outer metal layers, the first metal layer 31 and the second metal layer 32, without providing an inner metal layer.
[0080] (10) A first resist layer 81 is formed having openings 81X and 81Y that selectively expose the first inner surface 31A of the metal sheet 80, and the metal sheet 80 exposed from the openings 81X and 81Y is etched from the first inner surface 31A side. As a result, a first bottomed hole 41 and a first groove 42 are formed simultaneously on the first inner surface 31A of the first metal layer 31. Therefore, the number of manufacturing steps can be reduced compared to when the first bottomed hole 41 and the first groove 42 are formed in separate steps. In addition, both the first bottomed hole 41 and the first groove 42 can be formed using one first resist layer 81 as an etching mask.
[0081] (11) A first resist layer 81 having openings 81X, 81Y, and 81Z is formed on the first inner surface 31A of the metal sheet 80, and the metal sheet 80 exposed from the openings 81X, 81Y, and 81Z is etched from the first inner surface 31A side. As a result, a first bottomed hole 41, a first groove 42, and a first recess 71 are simultaneously formed on the first inner surface 31A of the first metal layer 31. Therefore, the number of manufacturing steps can be reduced compared to when the first bottomed hole 41, the first groove 42, and the first recess 71 are formed in separate steps.
[0082] (Other embodiments) The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.
[0083] In the above embodiment, the depth 71D of the first recess 71 is formed to be deeper than the depth 41D of the first bottomed hole 41, but the embodiment is not limited thereto. For example, the depth 71D of the first recess 71 may be formed to be the same depth as the depth 41D of the first bottomed hole 41.
[0084] In the above embodiment, the depth 72D of the second recess 72 was formed to be deeper than the depth 51D of the second bottomed hole 51, but this is not limited to this. For example, the depth 72D of the second recess 72 may be formed to be the same depth as the depth 51D of the second bottomed hole 51.
[0085] In the above embodiment, the depth 42D of the first groove 42 was formed to be shallower than the depth 41D of the first bottomed hole 41, but the embodiment is not limited to this. For example, the depth 42D of the first groove 42 may be formed to be the same depth as the depth 41D of the first bottomed hole 41.
[0086] In the above embodiment, the depth 52D of the second groove 52 was formed to be shallower than the depth 51D of the second bottomed hole 51, but this is not limited to this. For example, the depth 52D of the second groove 52 may be formed to be the same depth as the depth 51D of the second bottomed hole 51.
[0087] In the above embodiment, the depth 41D of the first blind hole 41 and the depth 51D of the second blind hole 51 may be different from each other. In the above embodiment, the depth 42D of the first groove 42 and the depth 52D of the second groove 52 may be different from each other.
[0088] In the above embodiment, the depth 71D of the first recess 71 and the depth 72D of the second recess 72 may be different from each other. The arrangement of the first and second blind holes 41 and 51 in the above embodiment can be changed as appropriate. For example, the arrangement of the first and second blind holes 41 and 51 is not particularly limited as long as they are arranged so that they are partially in communication with each other.
[0089] For example, as shown in Figure 17, a plurality of first blind holes 41 may be arranged in a staggered pattern in a plan view, and a plurality of second blind holes 51 may be arranged in a staggered pattern in a plan view. More specifically, in this modified example, the plurality of first blind holes 41 are arranged side by side along the X-axis direction and side by side along the Y-axis direction. However, adjacent first blind holes 41 in the X-axis direction are positioned offset from each other in the Y-axis direction. In this modified example, the plurality of second blind holes 51 are arranged side by side along the X-axis direction and side by side along the Y-axis direction. However, adjacent second blind holes 51 in the X-axis direction are positioned offset from each other in the Y-axis direction. The first blind holes 41 and the second blind holes 51 are arranged alternately along the Y-axis direction so that they partially overlap each other in a plan view. In addition, the first blind holes 41 and the second blind holes 51 are arranged alternately along the X-axis direction with a gap between them.
[0090] In this modified example, each first groove 42 is formed to connect two adjacent first bottomed holes 41 in the X-axis direction. Each first groove 42 in this modified example extends along the X-axis direction (first direction). The second groove 52 in this modified example is formed to connect two adjacent second bottomed holes 51 in the X-axis direction. Each second groove 52 in this modified example extends along the X-axis direction (first direction). Each second groove 52 is formed to extend parallel to each first groove 42. In this modified example as well, the first groove 42 and the second groove 52 are provided so as not to overlap each other in a plan view.
[0091] As shown in Figures 17 to 19, each first groove 42 in this modified example is provided so as to partially overlap with the second bottomed hole 51 in a plan view. Specifically, as shown in Figures 17 and 19, each first groove 42 in this modified example is provided so as to partially overlap with the second bottomed hole 51, which is located between two adjacent first bottomed holes 41 in the X-axis direction, in a plan view. As shown in Figures 18 and 19, each first groove 42 in this modified example is in direct communication with the second bottomed hole 51. In other words, the porous body 21s of this modified example has pores 62 formed by the partial communication between the first grooves 42 and the second bottomed holes 51. As shown in Figure 19, the pores 62 extend along the X-axis direction.
[0092] As shown in Figures 17 and 18, each second groove 52 in this modified example is provided so as to partially overlap with the first bottomed hole 41 in a plan view. Specifically, as shown in Figure 17, each second groove 52 in this modified example is provided so as to partially overlap with the first bottomed hole 41 located between two adjacent second bottomed holes 51 in the X-axis direction in a plan view. As shown in Figure 18, each second groove 52 in this modified example is in direct communication with the first bottomed hole 41. In other words, the porous body 21s of this modified example has pores 63 formed by the partial communication between the second grooves 52 and the first bottomed holes 41. The pores 63 extend along the X-axis direction.
[0093] Even with the configuration of the modified examples described above, the same effects and advantages as those of (1) to (11) of the above embodiments can be obtained. The structure of the liquid tube 24 in the above embodiment can be modified as appropriate. For example, the arrangement of the flow path 28 and the porous body 24s in the liquid tube 24 may be modified as appropriate. For example, the porous body 24s may be placed in the center of the liquid tube 24 in the width direction, and the flow paths 28 may be placed on both sides of the porous body 24s. For example, the flow paths 28 in the liquid tube 24 may be omitted.
[0094] • The steam pipe 22 in the above embodiment may be provided with a porous body similar to the porous body 21s. • The condenser 23 in the above embodiment may be provided with a porous body similar to the porous body 21s. [Explanation of symbols]
[0095] 20 Loop-type heat pipes 21 Evaporator 21s porous body 21w tube wall 22 Steam pipes 23 Condenser 24 liquid tubes 25 channels 31 1st metal layer 31A First inner surface 31B 1st outer surface 32 Second metal layer 32A Second inner surface 32B 2nd outer surface 41 1st bottomed hole 41D Depth 42 First groove 42D depth 51 2nd bottomed hole 51D Depth 52 Second groove 52D depth 61 pores 71 First recess 71D Depth 72 Second recess 72D depth 80 Metal Sheets 81 First Resist Layer 81X opening (1st opening) 81Y opening (second opening) 81Z opening 82 Second Resistance Layer C Working fluid M1 electronic equipment S2 space
Claims
1. An evaporator that vaporizes the working fluid, A condenser for liquefying the working fluid, A liquid pipe connecting the evaporator and the condenser, A steam pipe connecting the evaporator and the condenser, It has a loop-shaped flow path through which the working fluid flows, At least one structure of the evaporator, the condenser, the liquid pipe, and the vapor pipe is, A first metal layer having a first inner surface and a first outer surface that becomes the outer surface of the structure, A second metal layer having a second inner surface that is joined to the first inner surface and a second outer surface that becomes the outer surface of the structure, It has a porous body provided between the first outer surface and the second outer surface, The porous body A plurality of first bottomed holes provided on the first inner surface, Multiple second bottomed holes provided on the second inner surface, A pore formed by partially connecting the first bottomed hole and the second bottomed hole, A first groove is provided on the first inner surface and connects two or more of the first bottomed holes, It has a second groove provided on the second inner surface that connects two or more of the second bottomed holes, The first groove and the second groove are arranged in a loop-type heat pipe such that they do not overlap each other in a plan view.
2. The plurality of first bottomed holes are arranged in a line along a first direction and in a line along a second direction intersecting the first direction. The plurality of second bottomed holes are arranged in a line along the first direction and are also arranged in a line along the second direction. The first groove is formed to extend along the first direction, The loop-type heat pipe according to claim 1, wherein the second groove is formed to extend along the first direction.
3. The plurality of first bottomed holes are arranged in a grid pattern in a plan view. The plurality of second blind holes are arranged in a grid pattern in a plan view and are located at positions offset from the first blind hole in the second direction. The first groove is provided so as not to overlap with the second bottomed hole in a plan view. The loop-type heat pipe according to claim 2, wherein the second groove is provided so as not to overlap with the first bottomed hole in a plan view.
4. The plurality of first bottomed holes are arranged in a staggered pattern in a plan view. The plurality of second bottomed holes are arranged in a staggered pattern in a plan view. The first groove is provided so as to partially overlap with the second bottomed hole in a plan view. The loop-type heat pipe according to claim 2, wherein the second groove is provided so as to partially overlap the first bottomed hole in a plan view.
5. The first and second bottomed holes are arranged alternately along the second direction, The end of the first bottomed hole in the second direction is provided so as to partially overlap with the second bottomed hole in a plan view. The loop-type heat pipe according to claim 2, wherein the second direction extends along the direction in which the working fluid flows.
6. The first bottomed hole is formed to be deeper than the first groove. The loop-type heat pipe according to claim 1, wherein the second bottomed hole is formed deeper than the second groove.
7. The depth of the first groove is in the range of 0.5 times or more and less than 0.8 times the depth of the first bottomed hole. The loop-type heat pipe according to claim 6, wherein the depth of the second groove is in the range of 0.5 times or more and less than 0.8 times the depth of the second bottomed hole.
8. The width of the first groove is smaller than the width of the first bottomed hole. The loop-type heat pipe according to claim 1, wherein the width of the second groove is smaller than the width of the second bottomed hole.
9. The at least one structure is the evaporator, The evaporator has a space through which the vaporized working fluid moves. The space is formed by a first recess provided on the first inner surface and a second recess provided on the second inner surface communicating with each other. The aforementioned space is in communication with the flow path of the porous body. The first recess is formed to be deeper than the first bottomed hole. The loop-type heat pipe according to claim 1, wherein the second recess is formed to be deeper than the second bottomed hole.
10. A method for manufacturing a loop-type heat pipe, comprising: an evaporator for vaporizing a working fluid; a condenser for liquefying the working fluid; a liquid pipe connecting the evaporator and the condenser; a vapor pipe connecting the evaporator and the condenser; and a loop-shaped flow path through which the working fluid flows, A step of forming a first metal layer having a plurality of first blind holes and a first groove portion connecting two or more of the first blind holes on the first inner surface, A step of forming a second metal layer on a second inner surface, which is provided with a plurality of second blind holes and a second groove that connects two or more of the second blind holes, The evaporator comprises the step of forming the first metal layer and the second metal layer by stacking them with the first inner surface and the second inner surface facing each other, The step of forming the first metal layer is: A step of preparing a metal sheet having the first inner surface and the first outer surface, A step of forming a first resist layer that covers the first inner surface of the metal sheet, and a step of forming a second resist layer that covers the first outer surface of the metal sheet, A step of patterning the first resist layer to form a first opening and a second opening in the first resist layer that selectively expose the first inner surface of the metal sheet, The process includes the step of simultaneously forming a first bottomed hole and a first groove on the first inner surface by etching the metal sheet exposed from the first opening and the second opening from the first inner surface side, A method for manufacturing a loop-type heat pipe, wherein the first groove and the second groove are formed so that they do not overlap each other in a plan view.