heat pipe

Abstract

To provide a heat pipe to which a working fluid can be easily injected.SOLUTION: A loop-type heat pipe 10 includes an injection port 15 through which a working fluid is injected. The injection port 15 has a metal layer 31, a metal layer 33, a single-layer metal layer 32 arranged between the metal layer 31 and the metal layer 33, and an injection path 15r which is defined by the metal layer 31, the metal layer 32 and the metal layer 33 and in which the working fluid moves. The metal layer 31 has an inner face 31A lying opposite the metal layer 33 and constituting an inner face of the injection path 15r. The inner face 31A of the metal layer 31 has a plurality of groove parts 40.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heat pipe. [Background technology]

[0002] Conventionally, heat pipes that transport heat by utilizing the phase change of a working fluid have been proposed as devices for cooling heat-generating components of semiconductor devices (e.g., CPUs) mounted on electronic devices (see, for example, Patent Document 1). The working fluid is injected into the heat pipe through an inlet provided in the heat pipe. The inlet is then sealed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6146484 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, electronic devices such as mobile devices are becoming thinner. As electronic devices become thinner, there is a demand for thinner heat pipes as well. However, when heat pipes are made thinner, the inlet becomes smaller, making it difficult to inject the working fluid. Therefore, there is a demand for improving the injectability of the working fluid. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a heat pipe having an inlet for injecting a working fluid, the inlet having a first outer metal layer, a second outer metal layer, a single or multiple inner metal layers provided between the first outer metal layer and the second outer metal layer, and an injection path defined by the first outer metal layer, the second outer metal layer, and the inner metal layer and through which the working fluid moves, the first outer metal layer facing the second outer metal layer having a first inner surface constituting an inner surface of the injection path, the second outer metal layer faces the first outer metal layer and has a second inner surface that constitutes an inner surface of the injection path,The first inner surface of the first outer metal layer has one or more first grooves. The second inner surface of the second outer metal layer has one or more second groove portions, and the second groove portions are provided so as not to overlap the first groove portions in a plan view. . [Effects of the Invention]

[0006] According to one aspect of the present invention, it is possible to easily inject the working fluid. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic plan view showing a loop heat pipe according to an embodiment; [Figure 2] 1 is a schematic cross-sectional view of an inlet according to one embodiment. [Figure 3] 1 is a schematic cross-sectional view showing a loop heat pipe according to an embodiment of the present invention; [Figure 4] 1 is a schematic cross-sectional view showing a loop heat pipe according to an embodiment of the present invention; [Figure 5] 1 is a schematic cross-sectional view showing a loop heat pipe according to an embodiment of the present invention; [Figure 6] 5(a) to 5(d) are schematic cross-sectional views showing a method for manufacturing a loop heat pipe according to one embodiment. [Figure 7] 5(a) to 5(d) are schematic cross-sectional views showing a method for manufacturing a loop heat pipe according to one embodiment. [Figure 8] 1A and 1B are schematic cross-sectional views showing a method for manufacturing a loop heat pipe according to an embodiment of the present invention. [Figure 9] 1A and 1B are schematic cross-sectional views showing a method for manufacturing a loop heat pipe according to an embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a modified loop heat pipe. [Figure 11] FIG. 10 is a schematic cross-sectional view showing a modified loop heat pipe. [Figure 12] FIG. 10 is a schematic cross-sectional view showing a modified loop heat pipe. [Figure 13] FIG. 10 is a schematic cross-sectional view showing a modified loop heat pipe. [Figure 14]FIG. 10 is a schematic cross-sectional view showing a modified loop heat pipe. [Figure 15] FIG. 10 is a schematic cross-sectional view showing an injection port of a modified example. [Figure 16] FIG. 10 is a schematic plan view showing an injection port of a modified example. [Figure 17] FIG. 10 is a schematic cross-sectional view showing an injection port of a modified example. [Figure 18] 10(a) to 10(d) are schematic cross-sectional views showing a manufacturing method of a modified loop heat pipe. [Figure 19] 10(a) and 10(b) are schematic cross-sectional views showing a manufacturing method of a modified loop heat pipe. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment will be described below with reference to the accompanying drawings. For convenience, the accompanying drawings may show characteristic portions enlarged to make the features easier to understand, and the dimensional ratios of each component may differ from one drawing to another. In addition, in cross-sectional views, the hatching of some components is replaced with a matte finish, and some components are omitted, to make the cross-sectional structure of each component easier to understand. Each drawing illustrates the mutually orthogonal X-, Y-, and Z-axes. In the following description, for 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. In this specification, "planar view" refers to viewing an object from the Z-axis direction, and "planar shape" refers to the shape of an object viewed from the Z-axis direction. In this specification, "facing" refers to surfaces or components facing each other, and includes not only cases where they are completely facing each other, but also cases where they are partially facing each other. In this specification, the term "facing" includes not only the case where two members are separated from each other, but also the case where two members are in contact with each other.

[0009] (Overall configuration of the loop heat pipe 10) 1 is housed in a mobile electronic device M1 such as a smartphone or tablet computer. The loop heat pipe 10 includes an evaporator 11, a vapor pipe 12, a condenser 13, a liquid pipe 14, and an inlet 15.

[0010] The evaporator 11 and the condenser 13 are connected by a vapor pipe 12 and a liquid pipe 14. The evaporator 11 has a function of vaporizing the working fluid C to generate vapor Cv. The vapor Cv generated in the evaporator 11 is sent to the condenser 13 via the vapor pipe 12. The condenser 13 has a function of liquefying the vapor Cv of the working fluid C. The liquefied working fluid C is sent to the evaporator 11 via the liquid pipe 14. The vapor pipe 12 and the liquid pipe 14 form a loop-shaped flow path 16 through which the working fluid C or the vapor Cv flows.

[0011] The steam pipe 12 is formed, for example, as a long pipe. The liquid pipe 14 is formed, for example, as a long pipe. In this embodiment, the steam pipe 12 and the liquid pipe 14 have, for example, the same longitudinal dimension (i.e., length). The length of the steam pipe 12 and the length of the liquid pipe 14 may be different from each other. For example, the length of the steam pipe 12 may be shorter than the length of the liquid pipe 14. Here, the "length direction" of the evaporator 11, the steam pipe 12, the condenser 13, and the liquid pipe 14 in this specification refers to the direction that coincides with the direction in which the working fluid C or steam Cv flows in each component (see arrows in the figure). Furthermore, in this specification, "equal" includes not only cases where they are exactly equal, but also cases where there are slight differences between the compared objects due to the influence of dimensional tolerances, etc.

[0012] The evaporator 11 is fixed in close contact with a heat-generating component (not shown). The working fluid C in the evaporator 11 is vaporized by the heat generated by the heat-generating component, generating vapor Cv. A thermal interface material (TIM) may be interposed between the evaporator 11 and the heat-generating component. The thermal interface material reduces the contact thermal resistance between the heat-generating component and the evaporator 11, and facilitates smooth heat conduction from the heat-generating component to the evaporator 11.

[0013] The steam pipe 12 has, for example, a pair of pipe walls 12w provided on both sides in a width direction perpendicular to the longitudinal direction of the steam pipe 12 in a plan view, and a flow path 12r provided between the pair of pipe walls 12w. The flow path 12r communicates with the internal space of the evaporator 11. The flow path 12r is part of a loop-shaped flow path 16. Steam Cv generated in the evaporator 11 is led to the condenser 13 via the steam pipe 12.

[0014] The condenser 13 has, for example, a heat dissipation plate 13p with an increased area for heat dissipation and a meandering flow path 13r inside the heat dissipation plate 13p. The flow path 13r is a part of a loop-shaped flow path 16. The steam Cv introduced through the steam pipe 12 is liquefied in the condenser 13.

[0015] The liquid pipe 14 has, for example, a pair of pipe walls 14w provided on both sides in a width direction perpendicular to the longitudinal direction of the liquid pipe 14 in a plan view, and a flow path 14r provided between the pair of pipe walls 14w. The flow path 14r communicates with a flow path 13r of the condenser 13 and also communicates with the internal space of the evaporator 11. The flow path 14r is part of a loop-shaped flow path 16. The working fluid C liquefied in the condenser 13 is guided to the evaporator 11 through the liquid pipe 14.

[0016] In the loop heat pipe 10, heat generated in the heat-generating components is transferred to the condenser 13 and dissipated in the condenser 13. This cools the heat-generating components, suppressing a rise in temperature of the heat-generating components.

[0017] Here, it is preferable to use a fluid with a high vapor pressure and a large latent heat of vaporization as the working fluid C. By using such a working fluid C, the heat-generating components can be efficiently cooled by the latent heat of vaporization. Examples of the working fluid C that can be used include ammonia, water, chlorofluorocarbons, alcohol, and acetone.

[0018] (Configuration of injection port 15) The inlet 15 is an inlet for injecting the working fluid C into the loop heat pipe 10. That is, the inlet 15 is an inlet for injecting the working fluid C into the flow path 16. The inlet 15 has, for example, a length extending along the Y-axis direction, a width extending along the X-axis direction, and a thickness extending along the Z-axis direction. In the present embodiment, one end of the inlet 15 in the length direction is connected to the liquid pipe 14. The inlet 15 in the present embodiment injects the working fluid C into the liquid pipe 14. The inlet 15 may be connected to the evaporator 11, the steam pipe 12, or the condenser 13. In this case, the working fluid C injected into the flow path 16 moves from the injection point into the liquid pipe 14.

[0019] The inlet 15 is hermetically sealed after the working fluid C is injected. The sealed inlet 15 has, for example, an unsealed portion 21 connected to the liquid pipe 14 and a sealed portion 22 connected to the unsealed portion 21. In the loop heat pipe 10, for example, the liquid pipe 14, the unsealed portion 21, and the sealed portion 22 are formed continuously and integrally.

[0020] The unsealed portion 21, for example, generally maintains its shape before sealing, that is, the shape it has when the working fluid C is injected into the liquid pipe 14. The sealed portion 22, for example, has the same shape as the unsealed portion 21 when the working fluid C is injected into the liquid pipe 14, and is crushed and flattened after the working fluid C is injected into the liquid pipe 14. The flattening of the sealed portion 22 allows for airtight sealing so that the working fluid C injected into the liquid pipe 14 does not leak to the outside.

[0021] 2 to 4 show injection port 15 before sealing, i.e., injection port 15 in an unsealed state. FIG. 2 shows a cross section of injection port 15 at a position corresponding to line 2-2 in FIG. 1. The cross section shown in FIG. 2 is a cross section of injection port 15 cut along an XZ plane perpendicular to the longitudinal direction of injection port 15 (here, the Y-axis direction). FIG. 3 shows a cross section of injection port 15 and liquid pipe 14 at a position corresponding to line 3-3 in FIG. 2. FIG. 4 shows a cross section of injection port 15 and liquid pipe 14 at a position corresponding to line 4-4 in FIG. 3.

[0022] As shown in FIGS. 2 and 3, the injection port 15 has an injection channel 15r through which the working fluid C flows and a pair of pipe walls 15w provided on both sides of the injection channel 15r in the width direction of the injection port 15. As shown in FIGS. 3 and 4, the injection channel 15r extends, for example, along the Y-axis direction. The injection channel 15r has a first open end 15A and a second open end 15B provided at both ends of the injection channel 15r in the longitudinal direction (here, the Y-axis direction). The first open end 15A is connected, for example, to the outside of the loop heat pipe 10. In this embodiment, the first open end 15A is a portion that becomes the sealed portion 22 (see FIG. 1) after the working fluid C is injected. The second open end 15B is connected, for example, to the flow path 14r of the liquid pipe 14. The injection channel 15r is formed, for example, to communicate between the outside of the loop heat pipe 10 and the flow path 14r of the liquid pipe 14. The working fluid C is injected into the liquid pipe 14 through this injection path 15r.

[0023] 2, injection port 15 has a structure in which, for example, three metal layers 31, 32, and 33 are laminated. In other words, injection port 15 has a structure in which metal layer 32, which serves as an inner metal layer, is laminated between a pair of metal layers 31 and 33, which serve as outer metal layers. The inner metal layer of injection port 15 of this embodiment is composed of only one metal layer 32.

[0024] Each of the metal layers 31-33 is, for example, a copper (Cu) layer with excellent thermal conductivity. The multiple metal layers 31-33 are directly bonded to one another by solid-state bonding, such as diffusion bonding, pressure welding, friction welding, or ultrasonic bonding. In FIG. 2, the metal layers 31-33 are distinguished by solid lines for clarity. For example, when the metal layers 31-33 are integrated by diffusion bonding, the interfaces between the metal layers 31-33 may disappear, and the boundaries may not be clear. Here, solid-state bonding is a method in which the objects to be bonded are heated in a solid state (solid) to soften them without melting them, and then further heated to cause plastic deformation to bond them. The metal layers 31-33 are not limited to copper layers, and may be formed from stainless steel layers, aluminum layers, magnesium alloy layers, or the like. Furthermore, some of the stacked metal layers 31-33 may be made of a different material from the other metal layers. The thickness of each of the metal layers 31 to 33 can be, for example, about 50 μm to 200 μm. Note that some of the metal layers 31 to 33 may have a different thickness from the other metal layers, or all of the metal layers may have a different thickness from one another.

[0025] (Configuration of metal layer 32) Metal layer 32 is laminated between metal layer 31 and metal layer 33. The upper surface of metal layer 32 is bonded to metal layer 31. The lower surface of metal layer 32 is bonded to metal layer 33. Metal layer 32 has a through hole 32X that penetrates metal layer 32 in the thickness direction, and a pair of wall portions 32w provided on both sides of through hole 32X in the width direction of injection port 15. Through hole 32X constitutes injection path 15r.

[0026] (Configuration of metal layer 31) Metal layer 31 is laminated on the upper surface of metal layer 32. Metal layer 31 has an inner surface 31A (here, the lower surface) facing metal layer 33, and an outer surface 31B (here, the upper surface) provided on the opposite side of inner surface 31A in the thickness direction of metal layer 31 (here, the Z-axis direction). Metal layer 31 has wall portion 31w provided at a position overlapping wall portion 32w in a plan view, and upper wall 31u provided at a position overlapping injection path 15r in a plan view. Inner surface 31A of wall portion 31w is joined to the upper surface of wall portion 32w. Upper wall 31u is provided between the pair of wall portions 31w. Inner surface 31A of upper wall 31u is exposed to injection path 15r. In other words, inner surface 31A of upper wall 31u forms the inner surface of injection path 15r.

[0027] The metal layer 31 has one or more grooves 40 provided on the inner surface 31A. The metal layer 31 of this embodiment has four grooves 40. Each groove 40 is formed to communicate with the injection channel 15r. Each groove 40 is provided to overlap the injection channel 15r in a plan view. Each groove 40 is provided, for example, on the inner surface 31A of the upper wall 31u, i.e., on the inner surface 31A of the portion that constitutes the inner surface of the injection channel 15r. Each groove 40 of this embodiment is provided only on the inner surface 31A of the upper wall 31u of the inner surface 31A of the metal layer 31. In other words, each groove 40 of this embodiment is not provided on the inner surface 31A of the wall portion 31w. Each groove 40 is formed, for example, to be recessed from the inner surface 31A of the metal layer 31 to the middle portion of the metal layer 31 in the thickness direction. Each groove 40 is formed, for example, to extend from the inner surface 31A of the metal layer 31 to the center of the metal layer 31 in the thickness direction. The depth of each groove 40 can be, for example, about 25 μm to 100 μm. The width dimension of each groove 40 along the X-axis direction is formed to be sufficiently smaller than the width dimension of the injection path 15r along the X-axis direction. The width dimension of each groove 40 can be, for example, about 25 μm to 100 μm. In this way, a plurality of narrow grooves 40 are provided on the inner surface 31A in the portion that constitutes the inner surface of the injection path 15r.

[0028] The cross-sectional shape of the inner surface of each groove 40 can be any shape. The bottom surface of each groove 40 is formed into, for example, a curved surface that is curved in an arc shape. The inner side surface of each groove 40 is formed so as to extend perpendicular to the inner surface 31A of the metal layer 31, for example.

[0029] The plurality of grooves 40 are arranged side by side along one direction (here, the X-axis direction) in a planar direction perpendicular to the thickness direction of the metal layer 31. The plurality of grooves 40 are arranged, for example, at predetermined intervals along the X-axis direction.

[0030] As shown in FIG. 3, each groove 40 extends, for example, along the length direction of the injection port 15. Each groove 40 extends, for example, along one direction in a planar direction perpendicular to the thickness direction of the metal layer 31. Each groove 40 extends, for example, along a direction (here, the Y-axis direction) perpendicular to the direction in which the multiple grooves 40 are arranged (here, the X-axis direction). Each groove 40 extends, for example, in a direction corresponding to the movement direction of the working fluid C. The multiple grooves 40 are formed, for example, to extend parallel to each other.

[0031] Each groove 40 extends, for example, toward the liquid pipe 14. Each groove 40 extends, for example, from the first open end 15A of the injection channel 15r toward the liquid pipe 14. Each groove 40 extends, for example, from the first open end 15A to partway along the length of the injection channel 15r. In other words, each groove 40 does not extend to the second open end 15B along the length of the injection channel 15r. That is, each groove 40 does not extend to the flow path 14r of the liquid pipe 14. Each groove 40 is not connected to the flow path 14r, for example. Each groove 40 is formed, for example, so as not to directly communicate with the flow path 14r. Each groove 40 extends, for example, to a position where it overlaps with a portion of the pipe wall 14w of the liquid pipe 14 in the X-axis direction along the length of the injection channel 15r.

[0032] (Configuration of metal layer 33) As shown in FIG. 2, metal layer 33 is laminated on the lower surface of metal layer 32. Metal layer 33 has an inner surface 33A (here, the upper surface) facing metal layer 31 and an outer surface 33B (here, the lower surface) provided on the opposite side of inner surface 33A in the thickness direction of metal layer 33. Metal layer 33 has wall portion 33w provided at a position overlapping wall portion 32w in a plan view, and a lower wall 33d provided at a position overlapping injection path 15r in a plan view. Inner surface 33A of wall portion 33w is joined to the lower surface of wall portion 32w. Lower wall 33d is provided between the pair of wall portions 33w. Inner surface 33A of lower wall 33d is exposed to injection path 15r. In other words, inner surface 33A of lower wall 33d forms the inner surface of injection path 15r.

[0033] The metal layer 33 has one or more grooves 50 provided on the inner surface 33A. The metal layer 33 of this embodiment has five grooves 50. Each groove 50 is formed to communicate with the injection channel 15r. For example, each groove 50 is provided on the inner surface 33A of the lower wall 33d, i.e., on the inner surface 33A of the portion that constitutes the inner surface of the injection channel 15r. In this embodiment, each groove 50 is provided only on the inner surface 33A of the lower wall 33d among the inner surfaces 33A of the metal layer 33. In other words, each groove 50 of this embodiment is not provided on the inner surface 33A of the wall portion 33w. For example, each groove 50 is formed to recess from the inner surface 33A of the metal layer 33 to the middle portion of the metal layer 33 in the thickness direction. For example, each groove 50 is formed to extend from the inner surface 33A of the metal layer 33 to the middle portion of the metal layer 33 in the thickness direction. The depth of each groove 50 can be, for example, about 25 μm to 100 μm. The width dimension of each groove 50 along the X-axis direction is formed to be sufficiently smaller than the width dimension of the injection path 15r along the X-axis direction. The width dimension of each groove 50 along the X-axis direction is, for example, 40 The width of each groove 50 along the X-axis direction is equal to the width of each groove 50. The width of each groove 50 may be, for example, about 25 μm to 100 μm. In this way, a plurality of narrow grooves 50 are provided on inner surface 33A in the portion that constitutes the inner surface of injection path 15r.

[0034] The cross-sectional shape of the inner surface of each groove 50 can be any shape. The bottom surface of each groove 50 is formed into, for example, a curved surface that is curved in an arc shape. The inner side surface of each groove 50 is formed so as to extend perpendicular to the inner surface 33A of the metal layer 33, for example.

[0035] As shown in FIG. 3 , the plurality of grooves 50 are arranged side by side along one planar direction (here, the X-axis direction) perpendicular to the thickness direction of the metal layer 31. The plurality of grooves 50 are arranged, for example, at predetermined intervals along the X-axis direction. For example, each groove 50 is arranged so as not to overlap with a groove 40 in a plan view. For example, each groove 50 is arranged so as not to overlap with the entire groove 40 in a plan view. The plurality of grooves 50 are arranged along the X-axis direction at intervals so as not to overlap with the groove 40. For example, the interval between two grooves 50 adjacent to each other in the X-axis direction is greater than the width dimension of each of the grooves 40, 50. Furthermore, the interval between two grooves 40 adjacent to each other in the X-axis direction is greater than the width dimension of each of the grooves 40, 50.

[0036] Each groove 50 extends, for example, along one planar direction perpendicular to the thickness direction of the metal layer 31. Each groove 50 extends, for example, along a direction (here, the Y-axis direction) perpendicular to the direction in which the multiple grooves 50 are arranged (here, the X-axis direction). Each groove 50 extends, for example, in a direction corresponding to the movement direction of the working fluid C. The multiple grooves 50 are formed, for example, to extend parallel to each other. Each groove 50 is formed, for example, to extend parallel to the groove 40 in a plan view. The length dimension of each groove 50 along the Y-axis direction is, for example, equal to the length dimension of each groove 40 along the Y-axis direction.

[0037] Each groove 50 extends, for example, toward the liquid pipe 14. Each groove 50 extends, for example, from the first open end 15A of the injection channel 15r toward the liquid pipe 14. Each groove 50 extends, for example, from the first open end 15A to partway along the length of the injection channel 15r. In other words, each groove 50 does not extend to the second open end 15B along the length of the injection channel 15r. That is, each groove 50 does not extend to the flow path 14r of the liquid pipe 14. Each groove 50 is not connected to the flow path 14r, for example. Each groove 50 is formed, for example, so as not to be in direct communication with the flow path 14r. Each groove 50 extends, for example, to a position where it overlaps with a portion of the pipe wall 14w of the liquid pipe 14 in the X-axis direction along the length of the injection channel 15r.

[0038] (Specific structure of injection path 15r) 2, the injection path 15r is defined by the metal layer 31, the metal layer 32, and the metal layer 33. The injection path 15r is defined by a pair of wall portions 32w, an inner surface 31A of the upper wall 31u, and an inner surface 33A of the lower wall 33d. The injection path 15r is formed by, for example, a through hole 32X in the metal layer 32.

[0039] (Specific structure of pipe wall 15w) Each tube wall 15w is composed of, for example, a wall portion 31w of the metal layer 31, a wall portion 32w of the metal layer 32, and a wall portion 33w of the metal layer 33.

[0040] (Configuration of sealing portion 22) As shown in FIG. 5, the sealing portion 22 is formed by injecting the working fluid C into the flow path 14r of the liquid pipe 14 and then flattening and compressing the metal layers 31-33. For example, ultrasonic bonding can be used to form the sealing portion 22. Ultrasonic bonding bonds objects by applying ultrasonic waves while applying pressure to them. The objects may be heated to promote bonding. In the sealing portion 22, the metal layers 31-33 are compressed to block the injection path 15r. The sealing portion 22 separates the outside of the loop heat pipe 10 from the injection path 15r. Even if gaps are generated between the metal layers 31-33 in the sealing portion 22, hermetic sealing is achieved as long as the gaps do not connect the outside of the loop heat pipe 10 to the injection path 15r.

[0041] (Configuration of liquid pipe 14) Like the inlet 15, the liquid pipe 14 is formed by stacking three metal layers 31 to 33. As shown in FIG. 3, the liquid pipe 14 has a pair of pipe walls 14w provided on both sides in a width direction (here, the Y-axis direction) perpendicular to the length direction (here, the X-axis direction) of the liquid pipe 14. The liquid pipe 14 has, for example, a porous portion 60 and a flow path 61. The liquid pipe 14 of this embodiment has a pair of pipe walls 14w, a pair of porous portions 60 provided in the pair of pipe walls 14w, and a flow path 61 provided between the pair of porous portions 60. Each porous portion 60 is, for example, formed integrally and continuously with the corresponding pipe wall 14w. Each porous portion 60 is a structure having fine pores. Each porous portion 60 is configured to have, for example, a bottomed hole recessed from the upper surface of the metal layer 32, which is the inner metal layer, a bottomed hole recessed from the lower surface of the metal layer 32, and a fine pore formed by the bottomed holes partially communicating with each other. The porous portion 60 guides the working fluid C liquefied in the condenser 13 to the evaporator 11 (see FIG. 1 ) by, for example, capillary force generated in the porous portion 60. A portion of the porous portion 60 is exposed to the second opening end 15B of the injection path 15r. The porous portion 60 is in communication with, for example, the injection path 15r. However, the porous portion 60 is not connected to, for example, the groove portions 40, 50. In other words, the groove portions 40, 50 are not connected to the porous portion 60. That is, the groove portions 40, 50 are separated from the porous portion 60. Therefore, the groove portions 40, 50 are not in direct communication with the porous portion 60.

[0042] 4, the cross-sectional area of ​​the flow path 61 is formed to be larger than the cross-sectional area of ​​the flow path of the porous portion 60, for example. The flow path 61 is formed by a through-hole 32Y that penetrates the metal layer 32, which is the inner metal layer, in the thickness direction. For example, the flow path 61 is in communication with the flow path of the porous portion 60. In the liquid pipe 14 of this embodiment, the flow path 14r of the liquid pipe 14 is formed by the flow path of the porous portion 60 and the flow path 61.

[0043] (Configuration of loop heat pipe 10) The evaporator 11, steam pipe 12, and condenser 13 shown in FIG. 1 are formed by stacking three metal layers 31 to 33 (see FIG. 2), similar to the inlet 15 shown in FIG. 2. The evaporator 11 may have a porous portion similar to the porous portion 60 of the liquid pipe 14 (see FIG. 4). For example, the porous portion of the evaporator 11 is formed in a comb-like shape. Within the evaporator 11, a space is formed in an area where no porous portion is provided. For example, in the steam pipe 12, a flow path 12r is formed by forming a through-hole that penetrates the metal layer 32 (see FIG. 2), which is an inner metal layer, in the thickness direction. For example, in the condenser 13, a flow path 13r is formed by forming a through-hole that penetrates the metal layer 32 (see FIG. 2), which is an inner metal layer, in the thickness direction.

[0044] In this way, the loop heat pipe 10 is configured by stacking three metal layers 31 to 33 (see FIG. 2). The number of stacked metal layers is not limited to three, and can be four or more.

[0045] In this embodiment, the loop heat pipe 10 is an example of a heat pipe, the metal layer 31 is an example of a first outer metal layer, the inner surface 31A is an example of a first inner surface, the metal layer 32 is an example of an inner metal layer, the metal layer 33 is an example of a second outer metal layer, and the inner surface 33A is an example of a second inner surface. Also, the groove 40 is an example of a first groove, and the groove 50 is an example of a second groove.

[0046] (Function of loop heat pipe 10) Next, the operation of the loop heat pipe 10 will be described. The loop heat pipe 10 has an evaporator 11 that vaporizes the working fluid C, a vapor pipe 12 that flows the vaporized working fluid C (i.e., vapor Cv) into a condenser 13, a condenser 13 that liquefies the vapor Cv, and a liquid pipe 14 that flows the liquefied working fluid C into the evaporator 11. The vapor Cv generated in the evaporator 11 due to heat from the heat-generating components is guided to the condenser 13 through the vapor pipe 12. The vapor Cv is liquefied in the condenser 13. That is, the heat generated in the heat-generating components is dissipated in the condenser 13. This cools the heat-generating components, suppressing a rise in their temperature.

[0047] The loop heat pipe 10 has an inlet 15 for injecting a working fluid C into a flow path 16. The inlet 15 has an inlet channel 15r through which the working fluid C flows and multiple grooves 40, 50 formed on the inner surface of the inlet channel 15r. Each groove 40, 50 extends along the length of the inlet 15 toward the liquid pipe 14. The grooves 40, 50 generate capillary forces in the working fluid C when the working fluid C is injected into the loop heat pipe 10 through the inlet 15. This allows the working fluid C to be easily guided from the outside of the loop heat pipe 10 into the inside of the inlet channel 15r by the grooves 40, 50. The working fluid C then moves through the inlet channel 15r by the grooves 40, 50 and is injected into the flow path 14r of the liquid pipe 14 from the second open end 15B of the inlet channel 15r.

[0048] (Method of manufacturing the loop heat pipe 10) Next, a method for manufacturing the loop heat pipe 10 will be described. First, in the step shown in Fig. 6(a), a flat metal sheet 71 is prepared. The metal sheet 71 is a member that will eventually become the metal layer 31 (see Fig. 2). The metal sheet 71 is made of, for example, copper, stainless steel, aluminum, magnesium alloy, etc. The thickness of the metal sheet 71 can be, for example, about 50 µm to 200 µm.

[0049] Subsequently, a resist layer 72 is formed on the lower surface of the metal sheet 71, and a resist layer 73 is formed on the upper surface of the metal sheet 71. As the resist layers 72 and 73, for example, a photosensitive dry film resist or the like can be used.

[0050] 6(b), the resist layer 72 is exposed and developed to form openings 72X that selectively expose the lower surface of the metal sheet 71. The openings 72X are formed to correspond to the grooves 40 shown in FIG.

[0051] 6(c), the metal sheet 71 exposed in the opening 72X is etched (half-etched) from the lower surface side of the metal sheet 71. As a result, grooves 40 are formed on the lower surface of the metal sheet 71. The grooves 40 can be formed, for example, by wet-etching the metal sheet 71 using the resist layers 72 and 73 as an etching mask. When copper is used as the material of the metal sheet 71, an aqueous solution of ferric chloride or an aqueous solution of cupric chloride can be used as the etching solution.

[0052] Next, the resist layers 72 and 73 are removed with a remover, thereby forming the metal layer 31 having the grooves 40 on the inner surface 31A, as shown in FIG. Next, in the step shown in Fig. 7(a), a flat metal sheet 74 is prepared. The metal sheet 74 is a member that will eventually become the metal layer 32 (see Fig. 2). The metal sheet 74 is made of, for example, copper, stainless steel, aluminum, magnesium alloy, etc. The thickness of the metal sheet 74 can be, for example, about 50 µm to 200 µm.

[0053] Subsequently, a resist layer 75 is formed on the lower surface of the metal sheet 74, and a resist layer 76 is formed on the upper surface of the metal sheet 74. As the resist layers 75 and 76, for example, a photosensitive dry film resist or the like can be used.

[0054] 7(b), the resist layer 75 is exposed and developed to form openings 75X that selectively expose the lower surface of the metal sheet 74. Similarly, the resist layer 76 is exposed and developed to form openings 76X that selectively expose the upper surface of the metal sheet 74. The openings 75X and 76X are formed to correspond to the through holes 32X shown in FIG. 2. The openings 75X and 76X are positioned to overlap each other in a plan view.

[0055] 7(c), the metal sheet 74 exposed from the resist layers 75, 76 is etched from both the top and bottom surfaces of the metal sheet 74. The openings 75X, 76X form through-holes 32X in the metal sheet 74. The through-holes 32X can be formed, for example, by wet-etching the metal sheet 74 using the resist layers 75, 76 as an etching mask. When copper is used as the material of the metal sheet 74, an aqueous solution of ferric chloride or an aqueous solution of cupric chloride can be used as the etching solution.

[0056] Next, the resist layers 75 and 76 are removed with a remover, thereby forming the metal layer 32 having the through-holes 32X, as shown in FIG. 8(a), a metal layer 33 having grooves 50 on an inner surface 33A is formed by a method similar to the steps shown in FIGS. 6(a) to 6(d). Next, a metal layer 32 is disposed between the metal layer 31 and the metal layer 33.

[0057] 8(b), the stacked metal layers 31 to 33 are pressed while being heated to a predetermined temperature (for example, about 900°C), thereby bonding the metal layers 31 to 33 by solid-state bonding. As a result, the metal layers 31, 32, and 33 adjacent in the stacking direction are directly bonded.

[0058] The steps described above form a structure in which the metal layers 31, 32, and 33 are laminated. Then, the injection port 15 before sealing is formed, and the evaporator 11, the steam pipe 12, the condenser 13, and the liquid pipe 14 shown in FIG. 1 are formed.

[0059] Next, in the process shown in FIGS. 9(a) and 9(b), the liquid pipe 14 is evacuated using a vacuum pump or the like, and then the working fluid C is injected into the liquid pipe 14 through the inlet 15. At this time, capillary force is generated at the inlet 15 by the grooves 40, 50 provided on the inner surface of the injection path 15r. The capillary force generated by the grooves 40, 50 makes it easier to draw the working fluid C into the loop heat pipe 10. As a result, even if the inlet 15 for injecting the working fluid C becomes narrower as the loop heat pipe 10 is made thinner, a small amount of working fluid C can be stably drawn into the loop heat pipe 10.

[0060] Next, after the injection of the working fluid C is completed, a portion of the injection port 15 in the longitudinal direction is crushed and flattened to form the sealing portion 22 shown in Fig. 5, and the injection port 15 is airtightly sealed so that the working fluid C injected into the liquid pipe 14 does not leak to the outside. For example, the metal layers 31, 32, and 33 (see Fig. 8(b)) are pressed in the stacking direction in a portion of the longitudinal direction of the injection port 15 to form the sealing portion 22, thereby airtightly sealing the injection port 15.

[0061] Next, the effects of this embodiment will be described. (1) The loop heat pipe 10 has an inlet 15 for injecting the working fluid C into the flow path 16. The inlet 15 has an inlet passage 15r through which the working fluid C flows and a groove 40 formed on the inner surface 31A of the metal layer 31 at a portion constituting the inner surface of the inlet passage 15r. The groove 40 extends along the length of the inlet 15 toward the liquid pipe 14. The groove 40 generates a capillary force in the working fluid C when the working fluid C is injected into the flow path 16 through the inlet 15. The capillary force of the groove 40 facilitates drawing the working fluid C into the loop heat pipe 10. This makes it easier to inject the working fluid C into the loop heat pipe 10 than if the groove 40 were not provided. Therefore, even if the inlet 15 becomes narrower as the loop heat pipe 10 is made thinner, a small amount of working fluid C can be stably drawn into the loop heat pipe 10. In addition, since a small amount of working fluid C can be stably drawn into the interior, it is possible to improve the controllability of the amount of working fluid C injected, and the desired amount of working fluid C can be easily injected.

[0062] (2) The injection port 15 has a groove 50 formed on the inner surface 33A of the metal layer 33 in a portion that forms the inner surface of the injection channel 15r. The groove 50 extends along the length of the injection port 15 toward the liquid pipe 14. The groove 50 generates a capillary force in the working fluid C when the working fluid C is injected into the flow channel 16 through the injection port 15. The capillary force of the groove 50 makes it easier to draw the working fluid C into the loop heat pipe 10. This makes it easier to inject the working fluid C into the loop heat pipe 10 than if the groove 50 were not formed.

[0063] (3) Here, even if the inlet 15 is thinned in the thickness direction, the surface areas of the inner surfaces 31A and 33A that form the inner surface of the injection channel 15r on both sides of the inlet 15 in the thickness direction remain unchanged. Therefore, the surface areas of the inner surfaces 31A and 33A where the grooves 40 and 50 are formed can be maintained at a predetermined surface area regardless of the thinning of the inlet 15. As a result, even if the inlet 15 is thinned, the formation areas of the grooves 40 and 50 can be maintained. Therefore, the capillary force of the grooves 40 and 50 can be used to effectively draw the working fluid C into the loop heat pipe 10.

[0064] (4) However, when groove portion 40 and groove portion 50 are provided so as to overlap in a plan view, the upper wall 31u and the lower wall 33d constituting the pipe wall of injection path 15r are both thin at the same position where groove portions 40 and 50 are formed, which reduces rigidity and may result in damage due to the pressure when injecting working fluid C. In contrast, in injection port 15 of the present embodiment, groove portion 50 is provided so as not to overlap groove portion 40 in a plan view. That is, groove portion 40 and groove portion 50 are provided at positions offset from each other in a plan view. As a result, compared to when groove portion 40 and groove portion 50 are provided so as to overlap in a plan view, one of upper wall 31u and lower wall 33d constituting the pipe wall of injection path 15r is ensured to have a thicker wall thickness, thereby suppressing damage due to the pressure when injecting working fluid C.

[0065] (5) The grooves 40, 50 extend toward the liquid pipe 14 and are spaced apart from the porous portion 60 provided in the liquid pipe 14. That is, the grooves 40, 50 are formed so as not to be in direct communication with the porous portion 60. This allows the grooves 40, 50 to be designed separately from the design of the porous portion 60. That is, the grooves 40, 50 can be designed in any shape independent of the porous portion 60, and their positions can also be freely set. This improves the degree of freedom in designing the grooves 40, 50.

[0066] Moreover, the grooves 40, 50 are formed to be separated from the porous portion 60 so as not to be in direct communication with the porous portion 60. Therefore, the working fluid C can be stored in the grooves 40, 50, which are regions separated from the porous portion 60.

[0067] (6) The inner surface 31A of the metal layer 31 is provided with a large number of small grooves 40. The small width of each groove 40 enhances the capillary force of the grooves 40. Therefore, the large number of small grooves 40 makes it easier to draw the working fluid C into the loop heat pipe 10. This allows the working fluid C to be easily injected into the loop heat pipe 10.

[0068] (Other embodiments) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0069] In the above embodiment, the lengthwise dimensions of the plurality of grooves 40 are equal to each other, and the lengthwise dimensions of the plurality of grooves 50 are equal to each other, but this is not limiting. For example, the lengthwise dimensions of the plurality of grooves 40 may be set individually. For example, the lengthwise dimensions of the plurality of grooves 50 may be set individually.

[0070] 10, the plurality of groove portions 40 may include a groove portion 41 and a groove portion 42 that has a smaller longitudinal dimension than groove portion 41. In this modified example, the plurality of groove portions 40 includes two groove portions 41 and two groove portions 42. In this modified example, the longitudinal dimension of each groove portion 42 is set to about half the longitudinal dimension of groove portion 41.

[0071] The plurality of groove portions 50 may include, for example, groove portion 51 and groove portion 52 having a lengthwise dimension smaller than groove portion 51. In this modified example, the plurality of groove portions 50 includes three groove portions 51 and two groove portions 52. In this modified example, the lengthwise dimension of each groove portion 52 is set to about half the lengthwise dimension of groove portion 51.

[0072] In this configuration, a portion is formed in the longitudinal direction of injection path 15r where only groove portions 41 and 51 of groove portions 41, 42, 51, and 52 are provided. In this portion where only groove portions 41 and 51 are provided, the rigidity of upper wall 31u and lower wall 33d that constitute the pipe wall of injection path 15r can be increased compared to a portion where all of groove portions 41, 42, 51, and 52 are formed.

[0073] In the modification shown in FIG. 10, the number, arrangement and length of the grooves 41, 42, 51 and 52 can be changed as appropriate. In the above embodiment, the widthwise dimensions of the plurality of grooves 40 are equal to each other, and the widthwise dimensions of the plurality of grooves 50 are equal to each other, but this is not limiting. For example, the widthwise dimensions of the plurality of grooves 40 may be set individually. For example, the widthwise dimensions of the plurality of grooves 50 may be set individually.

[0074] In the above embodiment, the depth dimensions of the plurality of grooves 40 are equal to each other, and the depth dimensions of the plurality of grooves 50 are equal to each other, but this is not limiting. For example, the depth dimensions of the plurality of grooves 40 may be set individually. For example, the depth dimensions of the plurality of grooves 50 may be set individually.

[0075] In the above embodiment, the planar shape of each groove 40, 50 is formed into a rectangular shape extending along the Y-axis direction, but this is not limited thereto. The planar shape of each groove 40, 50 can be formed into any shape. For example, the planar shape of each groove 40, 50 can be changed as appropriate depending on the overall shape of the inlet 15, the flow direction of the working fluid C, etc.

[0076] For example, as shown in FIG. 11 , each groove 40, 50 may be formed to extend in a direction intersecting both the X-axis direction and the Y-axis direction in the XY plane. For example, each groove 40 may be formed to extend in a first direction intersecting both the X-axis direction and the Y-axis direction, and each groove 50 may be formed to extend in a second direction intersecting both the X-axis direction and the Y-axis direction and intersecting the first direction. In this case, the grooves 40 and 50 are formed to intersect with each other in a plan view. Therefore, in this modified example, the grooves 40 and 50 are formed to partially overlap with each other in a plan view. In this modified example, for example, a plurality of grooves 40 are arranged side by side along a third direction perpendicular to the first direction in the XY plane, and a plurality of grooves 50 are arranged side by side along a fourth direction perpendicular to the second direction in the XY plane.

[0077] 12, each groove 40 may be formed to extend in a first direction that intersects both the X-axis direction and the Y-axis direction, and each groove 50 may be formed to extend along the Y-axis direction. In this case, the groove 40 and the groove 50 are formed to partially overlap each other in a plan view.

[0078] In the above embodiment and each of the modified examples, the grooves 40, 50 are formed in both the unsealed portion 21 and the sealed portion 22, but this is not limitative. For example, the grooves 40, 50 in the above embodiment and each of the modified examples may not be provided in the sealed portion 22, but may be provided only in the unsealed portion 21.

[0079] For example, as shown in FIG. 13 , in the injection port 15 before the formation of the sealing portion 22, the grooves 40, 50 may not be provided in the portion that will become the sealing portion 22. In this modified example, the portion that will become the sealing portion 22 is provided in the middle of the injection path 15r in the longitudinal direction. In this modified example, the grooves 40, 50 are not provided in the middle of the injection path 15r in the longitudinal direction. In this modified example, the grooves 40, 50 extend along the Y-axis direction toward the liquid pipe 14 and are formed so as to be separated at the center of the injection path 15r in the longitudinal direction. Specifically, in this modified example, the grooves 40 include a groove 43 that is provided closer to the first opening end 15A in the Y-axis direction than the portion that will become the sealing portion 22, and a groove 44 that is provided closer to the second opening end 15B in the Y-axis direction than the portion that will become the sealing portion 22. Each groove 50 in this modified example has a groove 53 provided in the Y-axis direction closer to first opening end 15A than the portion that will become sealing portion 22, and a groove 54 provided in the Y-axis direction closer to second opening end 15B than the portion that will become sealing portion 22. These grooves 43, 44, 53, 54 are not provided in sealing portion 22 after sealing portion 22 is formed, but are provided only in unsealed portion 21.

[0080] According to this configuration, grooves 40, 50 are not provided in sealing portion 22, and therefore, the rigidity of injection port 15 in sealing portion 22 can be suitably prevented from decreasing. In the above embodiment and each of the above modifications, the grooves 40, 50 are formed to extend from the first open end 15A toward the liquid pipe 14 in the length direction of the injection port 15, but are not limited to this.

[0081] For example, as shown in FIG. 14, grooves 40, 50 may be formed to extend from a position away from first opening end 15A toward second opening end 15B in the length direction of inlet 15 toward liquid pipe 14.

[0082] As shown in Fig. 15, a porous body 80 may be provided in the injection port 15. The porous body 80 is provided, for example, in the wall portion 32w of the metal layer 32. In the injection port 15 of this modified example, a porous body 80 is provided in each of the two wall portions 32w. Each porous body 80 is formed integrally with the wall portion 32w, for example.

[0083] The porous body 80 of this modified example has bottomed holes 81 recessed from the upper surface of the metal layer 32, bottomed holes 82 recessed from the lower surface of the metal layer 32, and pores 83 formed by the bottomed holes 81 and 82 partially communicating with each other. The bottomed holes 81 are formed so as to recess from the upper surface of the metal layer 32 toward the center in the thickness direction of the metal layer 32. The bottomed holes 82 are formed so as to recess from the lower surface of the metal layer 32 toward the center in the thickness direction of the metal layer 32. The depth of the bottomed holes 81, 82 can be, for example, approximately 25 μm to 100 μm.

[0084] The inner surfaces of the bottomed holes 81, 82 are formed, for example, in a shape that continues in an arc from the opening side (the upper and lower surface sides of the metal layer 32) to the bottom side. The inner surfaces of the bottomed holes 81, 82 are formed as a curved surface that is curved in an arc shape in a cross-sectional view. The bottom surfaces of the bottomed holes 81, 82 are formed as a curved surface that is curved in an arc shape, for example. The bottom surfaces of the bottomed holes 81, 82 are formed, for example, as a curved surface that is curved in an arc shape. The bottom surfaces of the bottomed holes 81, 82 are formed, for example, as a continuation of the inner surfaces of the bottomed holes 81, 82. The radius of curvature of the bottom surfaces of the bottomed holes 81, 82 may be equal to or different from the radius of curvature of the inner surfaces of the bottomed holes 81, 82.

[0085] The inner surfaces of the bottomed holes 81, 82 may be concave, with a cross-sectional shape that is semicircular or semielliptical. In this specification, the term "semicircular" does not only refer to a semicircle obtained by dividing a perfect circle into two equal parts, but also includes shapes with longer or shorter arcs than a semicircle. In this specification, the term "semielliptical" does not only refer to a semiellipse obtained by dividing an ellipse into two equal parts, but also includes shapes with longer or shorter arcs than a semiellipse. The inner surfaces of the bottomed holes 81, 82 may be tapered, widening from the bottom side toward the opening side. The bottom surfaces of the bottomed holes 81, 82 may be formed as a flat surface parallel to the upper surface of the metal layer 32, and the inner side surfaces of the bottomed holes 81, 82 may be formed to extend perpendicular to the bottom surface.

[0086] 16, the bottomed holes 81, 82 are formed, for example, in a circular shape when viewed from above. The diameter of the bottomed holes 81, 82 may be, for example, approximately 100 μm to 400 μm. The planar shape of the bottomed holes 81, 82 may be any shape, such as an ellipse or a polygon.

[0087] The multiple bottomed holes 81 are arranged side by side, for example, along one planar direction (here, the Y-axis direction) perpendicular to the thickness direction of the metal layer 32. The multiple bottomed holes 81 are arranged, for example, at predetermined intervals along the Y-axis direction. The multiple bottomed holes 82 are arranged, for example, along one planar direction (here, the Y-axis direction) perpendicular to the thickness direction of the metal layer 32. The multiple bottomed holes 82 are arranged, for example, at predetermined intervals along the Y-axis direction. The multiple bottomed holes 81, 82 in this modified example are arranged side by side in a straight line along the Y-axis direction. Each bottomed hole 81 is arranged so as to partially overlap with a bottomed hole 82 in a planar view. Each bottomed hole 81 is arranged so as to partially overlap with each of two bottomed holes 82 adjacent to each other in the Y-axis direction in a planar view. Each bottomed hole 81 is formed so as to communicate with two bottomed holes 82 adjacent to each other in the Y-axis direction. Furthermore, each bottomed hole 82 is provided so as to partially overlap with each of two bottomed holes 81 adjacent to it in the Y-axis direction in plan view. Each bottomed hole 82 is formed so as to communicate with two bottomed holes 81 adjacent to it in the Y-axis direction. In the area where the bottomed hole 81 and the bottomed hole 82 overlap in plan view, the bottomed hole 81 and the bottomed hole 82 partially communicate with each other to form a pore 83. Note that in Figure 16, the metal layer 31 is drawn perspectively.

[0088] 15, the bottomed holes 81, 82 are provided, for example, away from the side surface of the wall portion 32w that constitutes the inner surface of the injection channel 15r. Therefore, the bottomed holes 81, 82 are provided away from the injection channel 15r in the X-axis direction. In other words, the bottomed holes 81, 82 are provided in the middle portion of the wall portion 32w in the width direction. The bottomed holes 81, 82 are not directly connected to the injection channel 15r. The bottomed holes 81, 82 are not directly connected to the injection channel 15r.

[0089] The grooves 40, 50 of this modified example are formed so as to connect the porous body 80 and the injection passage 15r. The groove 40 of this modified example is formed so as to connect the bottomed hole 81 and the injection passage 15r. The groove 40 is formed, for example, on the inner surface 31A of the upper wall 31u, and is formed on the wall 31 16, each groove 40 is formed on the inner surface 31A of the wall portion 33w. As shown in FIG. 16, each groove 40 is formed, for example, to connect one bottomed hole 81 to the injection channel 15r. For example, in a plan view, each groove 40 is formed to extend in a direction intersecting both the X-axis direction and the Y-axis direction. For example, each groove 40 is formed to extend from the first opening end 15A side toward the corresponding bottomed hole 81. As shown in FIG. 15, the groove 50 of this modified example is formed to connect the bottomed hole 82 to the injection channel 15r. For example, the groove 50 is formed on the inner surface 33A of the bottom wall 33d and the inner surface 33A of the wall portion 33w. As shown in FIG. 16, each groove 50 is formed, for example, to connect one bottomed hole 82 to the injection channel 15r. For example, in a plan view, each groove 50 is formed to extend in a direction intersecting both the X-axis direction and the Y-axis direction. Each groove 50 is formed, for example, to extend from each bottomed hole 82 toward the liquid pipe 14 (see FIG. 3). Thus, in the injection port 15 of this modified example, the bottomed holes 81, 82, the pore 83, and the grooves 40, 50 are in communication with one another. The space formed by the communication between these bottomed holes 81, 82, the pore 83, and the grooves 40, 50 expands three-dimensionally. Note that FIGS. 15 and 16 show the injection port 15 before sealing. Also, FIG. 15 shows a cross section of the injection port 15 at a position corresponding to the line 15a-15a in FIG. 16.

[0090] With this configuration, when the working fluid C is injected into the flow path 16 through the inlet 15, capillary force is generated by the grooves 40, 50 provided on the inner surface of the inlet 15, and capillary force is also generated by the porous body 80 provided in the inlet 15. The capillary force generated by the grooves 40, 50 and the porous body 80 makes it easier to draw the working fluid C into the loop heat pipe 10. This makes it easier to inject the working fluid C into the loop heat pipe 10 compared to when the grooves 40, 50 and the porous body 80 are not provided.

[0091] In this modified example, the bottomed hole 81 is an example of a first bottomed hole, and the bottomed hole 82 is an example of a second bottomed hole. In the above embodiment, the groove portion 40 and the groove portion 50 do not overlap each other in a plan view, but this is not limiting. For example, the groove portion 40 and the groove portion 50 may be provided so as to overlap each other in a plan view. For example, the groove portion 40 may be formed so as to overlap the groove portion 50 in a plan view. For example, the groove portion 40 and the groove portion 50 may be provided so as to partially overlap each other in a plan view.

[0092] The cross-sectional shape of the grooves 40, 50 in the above embodiment can be modified as appropriate. For example, the inner surface of each groove 40, 50 may be tapered, widening from the bottom side toward the opening side. The inner surface of each groove 40, 50 may be formed into a shape that continues in an arc from the opening side to the bottom side. The inner surface of each groove 40, 50 may be formed into a concave shape with a semicircular or semi-elliptical cross-sectional shape. The bottom surface of each groove 40, 50 may be formed as a plane parallel to the inner surface 31A of the metal layer 31, and the inner side surface of each groove 40, 50 may be formed to extend perpendicular to the bottom surface.

[0093] In the above embodiment, the plurality of grooves 40, 50 are provided at predetermined intervals in the X-axis direction, but this is not limitative. For example, as shown in Figure 17, multiple grooves 40 may be formed in a continuous manner. In this modified example, the multiple grooves 40 are formed continuously along the width direction of the injection port 15 (here, the X-axis direction). The inner surface of each groove 40 is formed, for example, in a concave shape with a semi-elliptical or semi-circular cross-sectional shape. In this modified example, the cross-sectional shape of the inner surface of each groove 40 is formed in a semicircular arc shape. The cross-sectional shape of the inner surface of the multiple grooves 40 is formed in a shape in which the semicircular arcs of the multiple grooves 40 are continuous along the X-axis direction.

[0094] Similarly, multiple grooves 50 may be formed in a continuous manner. The multiple grooves 50 in this modified example are formed continuously along the width direction of the injection port 15 (here, the X-axis direction). The inner surface of each groove 50 is formed, for example, in a concave shape with a semi-elliptical or semi-circular cross-sectional shape. The cross-sectional shape of the inner surface of each groove 50 in this modified example is formed in a semicircular arc shape. The cross-sectional shape of the inner surface of the multiple grooves 50 is formed in a shape in which the semicircular arcs of the multiple grooves 50 are continuous along the X-axis direction. Each groove 50 in this modified example is formed to overlap with each groove 40 in a plan view.

[0095] Next, a manufacturing method of the loop heat pipe 10 of this modified example will be described with reference to FIGS. First, in the step shown in Fig. 18(a), a flat metal sheet 91 is prepared. The metal sheet 91 is a member that will eventually become the metal layer 31 shown in Fig. 17. The metal sheet 91 is made of, for example, copper, stainless steel, aluminum, magnesium alloy, etc. The thickness of the metal sheet 91 can be, for example, about 50 µm to 200 µm.

[0096] Subsequently, a resist layer 92 is formed on the lower surface of the metal sheet 91, and a resist layer 93 is formed on the upper surface of the metal sheet 91. As the resist layers 92 and 93, for example, a photosensitive dry film resist or the like can be used.

[0097] 18(b), the resist layer 92 is exposed and developed to form a plurality of openings 92X that selectively expose the lower surface of the metal sheet 91. The openings 92X are formed to correspond to the plurality of grooves 40 shown in FIG.

[0098] 18(c), the metal sheet 91 exposed in the opening 92X is etched (half-etched) from the lower surface side of the metal sheet 91. As a result, a plurality of grooves 40 are formed in the lower surface of the metal sheet 91, extending in the left-right direction in the figure. For example, a ferric chloride solution can be used to etch the metal sheet 91.

[0099] Subsequently, the resist layers 92 and 93 are removed with a remover, thereby forming a metal layer 31 having recesses each having a plurality of continuous semicircular arcs on the inner surface 31A, i.e., a plurality of grooves 40, as shown in FIG.

[0100] Next, in the process shown in Figure 19(a), a metal layer 33 is formed by a method similar to the processes shown in Figures 18(a) to 18(d), and a metal layer 32 is formed by a method similar to the processes shown in Figures 7(a) to 7(d).

[0101] 19(b), the stacked metal layers 31 to 33 are pressed while being heated to a predetermined temperature (for example, about 900°C), thereby bonding the metal layers 31 to 33 by solid-state bonding. Through the above steps, the structure shown in FIG. 17 can be manufactured, and the loop heat pipe 10 of this modified example can be manufactured.

[0102] In the loop heat pipe 10 of the above embodiment, the inner metal layer is configured with only a single metal layer 32. That is, the inner metal layer has a single-layer structure. However, this is not limiting. For example, the inner metal layer may have a layered structure in which multiple metal layers are stacked. In this case, the inner metal layer is configured by stacking multiple metal layers between the metal layer 31 and the metal layer 33.

[0103] The inlet 15 of the above embodiment may be applied to a heat pipe having a shape other than the loop heat pipe 10. For example, the inlet 15 may be applied to a flat heat pipe. The above various embodiments can be summarized as follows. (Appendix 1) A heat pipe having an inlet for injecting a working fluid, The inlet is a first outer metal layer; A second outer metal layer; a single or multiple inner metal layer provided between the first outer metal layer and the second outer metal layer; an injection path defined by the first outer metal layer, the second outer metal layer, and the inner metal layer, through which the working fluid moves; the first outer metal layer faces the second outer metal layer and has a first inner surface that constitutes an inner surface of the injection path; The first inner surface of the first outer metal layer of the heat pipe has one or more first groove portions. (Appendix 2) the second outer metal layer faces the first outer metal layer and has a second inner surface that constitutes an inner surface of the injection path, 2. The heat pipe of claim 1, wherein the second inner surface of the second outer metal layer has one or more second groove portions. (Appendix 3) 3. The heat pipe according to claim 2, wherein the second groove portions are provided so as not to overlap with the first groove portions in a plan view. (Appendix 4) 3. The heat pipe according to claim 2, wherein the second grooves are provided so as to partially overlap the first grooves in a plan view. (Appendix 5) the injection port has an unsealed portion and a sealed portion connected to the unsealed portion, 5. The heat pipe according to claim 1, wherein the first groove portion is not provided in the sealed portion, but is provided only in the unsealed portion. (Appendix 6) the inlet has a porous body; the porous body has first bottomed holes recessed from one surface side of the inner layer metal layer, second bottomed holes recessed from the other surface side of the inner layer metal layer, and pores formed by partial communication between the first bottomed holes and the second bottomed holes, 6. The heat pipe according to claim 1, wherein the first groove portion is formed so as to communicate the first bottomed hole with the injection channel. (Appendix 7) the inner metal layer has a through hole penetrating the inner metal layer in a thickness direction, and a pair of wall portions provided on both sides of the through hole in a width direction of the injection port, the injection path is defined by the pair of wall portions, the first outer metal layer, and the second outer metal layer; 7. The heat pipe according to claim 6, wherein the porous body is provided in the wall portion. (Appendix 8) 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; a loop-shaped flow path through which the working fluid flows, 8. The heat pipe according to claim 1, wherein the injection channel is provided so as to communicate with the flow channel. (Appendix 9) the inlet is connected to the liquid pipe; the liquid pipe has a porous portion; 9. The heat pipe according to claim 8, wherein the first groove portion extends toward the liquid pipe and is spaced apart from the porous portion of the liquid pipe. (Appendix 10) the first outer metal layer has a plurality of the first groove portions, 10. The heat pipe according to claim 1, wherein the plurality of first groove portions are formed continuously with one another in a width direction of the inlet. [Explanation of symbols]

[0104] C Working fluid CV Steam M1 electronic equipment 10 Loop heat pipe 11 Evaporator 12 Steam Pipe 12r, 13r, 14r, 16 flow paths 13 Condenser 14 Liquid pipe 15 Inlet 15r injection path 15w tube wall 21 Unsealed area 22 Sealing part 31 Metal layer 31A Inner surface 31u upper wall 31w wall 32 Metal layer 32w wall 32X through hole 33 Metal layer 33A Inner surface 33d lower wall 33w wall 40, 41, 42, 43, 44 Groove 50, 51, 52, 53, 54 Groove 60 Porous part 80 Porous materials 81 Bottomed hole 82 Bottomed hole 83 pores

Claims

1. A heat pipe having an inlet for injecting a working fluid, The inlet is a first outer metal layer; a second outer metal layer; a single or multiple inner metal layer provided between the first outer metal layer and the second outer metal layer; an injection path defined by the first outer metal layer, the second outer metal layer, and the inner metal layer, and through which the working fluid moves; the first outer metal layer faces the second outer metal layer and has a first inner surface that constitutes an inner surface of the injection path, the second outer metal layer faces the first outer metal layer and has a second inner surface that constitutes an inner surface of the injection path, the first inner surface of the first outer metal layer has one or more first groove portions, the second inner surface of the second outer metal layer has one or more second groove portions, The second groove portion is provided so as not to overlap with the first groove portion in a plan view of the heat pipe.

2. the injection port has an unsealed portion and a sealed portion connected to the unsealed portion, The heat pipe according to claim 1 , wherein the first groove is not provided in the sealed portion, but is provided only in the unsealed portion.

3. the inlet has a porous body; the porous body has first bottomed holes recessed from one surface side of the inner metal layer, second bottomed holes recessed from the other surface side of the inner metal layer, and pores formed by the first bottomed holes and the second bottomed holes partially communicating with each other, The heat pipe according to claim 1 , wherein the first groove portion is formed so as to communicate the first bottomed hole with the injection channel.

4. the inner metal layer has a through hole penetrating the inner metal layer in a thickness direction, and a pair of wall portions provided on both sides of the through hole in a width direction of the injection port, the injection path is defined by the pair of wall portions, the first outer metal layer, and the second outer metal layer; The heat pipe according to claim 3 , wherein the porous body is provided in the wall portion.

5. 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; a loop-shaped flow path through which the working fluid flows, The heat pipe according to claim 1 , wherein the injection passage is provided so as to communicate with the flow passage.

6. the inlet is connected to the liquid pipe; the liquid pipe has a porous portion; The heat pipe according to claim 5 , wherein the first groove portion extends toward the liquid pipe and is spaced apart from the porous portion of the liquid pipe.

7. the first outer metal layer has a plurality of the first groove portions, The heat pipe according to claim 1 , wherein the plurality of first grooves are formed continuously with one another in a width direction of the injection port.

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