Sheet-shaped heat pipe

Abstract

To provide a sheet-like heat pipe capable of securing a vapor passage through which a gas-phase working fluid flows even if the thickness is reduced.SOLUTION: A sheet-shaped heat-pipe 1 according to the present invention is a SHP1 in which an internal space S is formed between a heat-dissipating plate 2 and a heat-receiving plate 3, a wick 4 and a working fluid are sealed in the internal space S, slit portions 15A to 15D extending from the vicinity of a heat-source P are formed in the wick 4, and the slit portions 15A to 15D are a part of a vapor-passage S2.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet-shaped heat pipe that is mounted on a device such as a smartphone or tablet terminal, receives heat from a heat source provided in the device, and cools the heat source by transporting the heat. [Background technology]

[0002] BACKGROUND ART Sheet-shaped heat pipes have been proposed for use in devices such as smartphones and tablet terminals, which dissipate heat generated by CPUs and other components for cooling (see, for example, Patent Document 1).

[0003] The sheet-like heat pipe (1) described in Patent Document 1 is made by overlapping and bonding two metal foils, a first sheet body (11) and a second sheet body (12), and enclosing a working fluid such as pure water in a vacuum state inside, and a wick (31) that circulates the working fluid, mainly in a liquid phase, by capillary force. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-030213 Summary of the Invention [Problem to be solved by the invention]

[0005] This sheet-like heat pipe (1) is formed to have a thickness (T0) of less than 0.4 mm. However, if the thickness (T0) is made too thin, the vapor passage (21) through which the gaseous working fluid flows becomes narrow, the flow rate of the working fluid per unit time decreases, heat transport becomes insufficient, and there is a problem that a sufficient cooling effect of the heat source cannot be obtained.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sheet-shaped heat pipe that can solve the above problems and ensure a vapor passage through which a gas-phase working fluid flows even when the thickness is reduced. [Means for solving the problem]

[0007] The sheet-type heat pipe of the present invention is a sheet-type heat pipe having an internal space formed between a first plate and a second plate, characterized in that a capillary structure and a working fluid are sealed in the internal space, and the capillary structure has a slit portion formed therein extending from near the heat source. [Effects of the Invention]

[0008] According to the present invention, even if the thickness of the sheet-shaped heat pipe is thin, it is possible to ensure a sufficient vapor passage through which the gas-phase working fluid flows. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a plan view of a heat dissipation plate according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the heat receiving plate of the embodiment. [Figure 3] FIG. 2 is a plan view of the wick of the same embodiment. [Figure 4] FIG. 2 is a plan view perspective view showing the internal structure of the sheet-shaped heat pipe of the embodiment. [Figure 5] FIG. 2 is a left side view of the sheet-shaped heat pipe of the embodiment. [Figure 6] 5 is a cross-sectional view taken along the line AA in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, preferred embodiments of a sheet-type heat pipe (hereinafter referred to as "SHP") according to the present invention will be described with reference to the drawings. Not all of the configurations described below are essential requirements for the present invention.

[0011] As shown in Figures 1 to 6, an SHP1 in one embodiment of the present invention is configured to have a heat dissipation plate 2 as a first plate, a heat reception plate 3 as a second plate, and a wick 4 as a capillary structure housed inside.

[0012] The heat dissipating plate 2 and the heat receiving plate 3 of this embodiment are made of austenitic stainless steel, and the wick 4 is housed (enclosed) in an internal space S (see FIG. 6) formed by joining the outer periphery 5 of the heat dissipating plate 2 and the outer periphery 6 of the heat receiving plate 3. Note that the heat dissipating plate 2 and the heat receiving plate 3 may be made of an alloy containing titanium or copper as a main component, in addition to stainless steel.

[0013] As shown in Figures 1, 5 and 6, the heat dissipation plate 2 is formed in a thin plate shape and has a flat portion 7 formed flat, and a plurality of first column portions 8 and a plurality of second column portions 9 protruding toward the heat receiving plate 3.

[0014] As shown in Figure 6, the first columnar portion 8 has a cylindrical shape tapered toward the heat receiving plate 3, and has an abutment surface portion 11 that abuts against the bottom surface portion 10 of the heat receiving plate 3. The second columnar portion 9 has a cylindrical shape tapered toward the heat receiving plate 3, and has a clamping surface portion 12 that abuts against the wick 4. The abutment surface portion 11 and the clamping surface portion 12 are disk-shaped and are arranged parallel to the bottom surface portion 10 of the heat receiving plate 3. The height H of the first columnar portion 8 is higher (longer) than the height h of the second columnar portion 9.

[0015] In this embodiment, the first column portion 8 and the second column portion 9 are arranged in a regular triangular lattice pattern, but as long as deformation of the heat dissipation plate 2 and the heat receiving plate 3 due to expansion and contraction of the internal space S and lifting or misalignment of the wick 4 can be prevented, they may also be arranged in a diagonal lattice pattern, a square lattice pattern, a rectangular lattice pattern, a rectangular lattice pattern, etc., or may also be arranged irregularly.

[0016] The first column section 8 and the second column section 9 of this embodiment are formed by drawing the heat dissipation plate 2. Although the first column section 8 and the second column section 9 of this embodiment are cylindrical, they may also be square tubular sections with polygonal cross sections. Furthermore, the first column section 8 and the second column section 9 may also be formed solid by etching.

[0017] As shown in Figures 2, 5 and 6, the heat receiving plate 3 is formed in a thin plate shape and has an outer peripheral portion 6 that joins with the outer peripheral portion 5 of the heat dissipation plate 2, and a housing portion 13 that protrudes in the opposite direction from the heat dissipation plate 2. The housing portion 13 integrally has a bottom surface portion 10 and an inclined wall portion 14 that connects the outer peripheral portion 6 and the bottom surface portion 10. The bottom surface portion 10 is formed flat. The heat receiving plate 3 of this embodiment is formed by drawing.

[0018] The wick 4 has a capillary structure with fine gaps evenly distributed throughout to generate a strong capillary force in the liquid-phase working fluid. Examples of the wick 4 include a flat mesh body formed by weaving metal wires aligned vertically and horizontally, a flat metal foil (not shown) having fine intersecting grooves on its surface that generate capillary force and holes arranged at equal intervals in the grooves, and a nonwoven fabric (not shown). As shown in FIG. 3 , in this embodiment, a flat mesh body is used as the wick 4. The outer shape of the wick 4 in this embodiment is substantially the same as the shape of the bottom surface 10 of the heat-receiving plate 3, but other outer shapes may be used as long as they generate a capillary force that can move the liquid-phase working fluid. In addition to the gaps between the vertical and horizontal metal wires, the wick 4 also has multiple slits 15A, 15B, 15C, and 15D.

[0019] In this embodiment, the four slit portions 15A to 15D are arranged in parallel along the longitudinal direction of the SHP 1. The reason that the slit portion 15A is formed shorter than the other slit portions 15B, 15C, and 15D is to match the shape of the wick 4. If the shape of the wick 4 is different, the lengths of the slit portions 15A to 15D can be adjusted to match the shape of the wick 4.

[0020] In the SHP1 of this embodiment, the heat source P (see FIGS. 4 and 5), which is the object to be cooled, comes into direct or indirect contact with the heat receiving plate 3. However, the slits 15 are not formed at the position where the heat source P comes into contact, but extend from the vicinity of the heat source P. In other words, the position where the heat source P comes into contact and the position where the slits 15 are formed do not overlap. This is because the wick 4 is provided at the position where the heat source P comes into contact, and the liquid phase working fluid is caused to flow to the position of the heat source P by capillary force. The slits 15A to 15D extend to the vicinity of the farthest end 16 of the wick 4, which is the farthest from the position where the heat source P comes into contact. The slits 15A to 15D may extend to the farthest end 16 of the wick 4, forming the wick 4 into a five-tooth comb shape. However, having the farthest end 16 of the wick 4 connected makes it easier to handle during manufacturing, such as when incorporating the wick 4 into the heat receiving plate 3.

[0021] The slits 15A to 15D are through holes formed in the wick 4, and the first columnar portion 8 is inserted through the slits 15A to 15D. The longitudinal ends 17A, 17B, 17C, and 17D on one side and the ends 18A, 18B, 18C, and 18D on the other side of the slits 15A to 15D are inclined so that the first columnar portion 8 and the second columnar portion 9 do not come into contact with the ends 17A to 17D on one side and the ends 18A to 18D on the other side. If the first columnar portion 8 and the second columnar portion 9 are arranged differently from this embodiment, the shapes of the ends 17A to 17D on one side and the ends 18A to 18D on the other side can be determined to match the positions of the first columnar portion 8 and the second columnar portion 9.

[0022] In this embodiment, the widths w1, w2, w3, and w4 of the slit portions 15A to 15D are set to allow two rows of the first column portions 8 to be arranged, but may be set to allow one or more rows of the first column portions 8 to be arranged. Furthermore, the widths w1 to w4 of the slit portions 15A to 15D may be different lengths. In this case, the widths w1 to w4 of the slit portions 15A to 15D are determined to ensure sufficient heat transport, taking into consideration the volume of the internal space S secured by forming the slit portions 15A to 15D and the capillary force of the wick 4. In this embodiment, the width W, which is the length in the short direction of the wick 4 where the slit portions 15A to 15D are formed, is 30.7 mm, and the widths w1 to w4 of the slit portions 15A to 15D are each 3.0 mm. The slit portions 15A to 15D are formed so that the total area is smaller than the area of ​​the wick 4, ensuring the necessary capillary force of the wick 4.

[0023] As shown in Figure 6, the internal space S has gaps S1, which are gaps between the vertical and horizontal metal wires of the wick 4, and vapor passages S2, which are spaces other than the gaps S1 of the wick 4. Liquid-phase working fluid flows mainly through the gaps S1, and gas-phase working fluid flows mainly through the vapor passages S2. The slits 15A to 15D reduce the volume of the gaps S1 and increase the volume of the vapor passages S2. Therefore, the slits 15A to 15D increase the flow rate of the gas-phase working fluid.

[0024] In this embodiment, the heat dissipation plate 2 and the heat receiving plate 3 each have a plate thickness of 0.03 mm (upper limit: 0.035 mm, lower limit: 0.025 mm), and the thickness M of the wick 4 is 0.045 mm (upper limit: 0.055 mm, lower limit: 0.035 mm). The height H of the first columnar portion 8 is 0.17 mm (upper limit: 0.175 mm, lower limit: 0.165 mm), and the height h of the second columnar portion is 0.125 mm (upper limit: 0.130 mm, lower limit: 0.120 mm). Furthermore, the distance L1 between the flat portion 7 of the heat dissipation plate 2 and the bottom surface 10 of the heat receiving plate 3 is 0.14 mm (upper limit: 0.145 mm, lower limit: 0.135 mm), and the distance L2 between the flat portion 7 of the heat dissipation plate 2 and the wick 4 is 0.095 mm (upper limit: 0.100 mm, lower limit: 0.090 mm). The thickness T of the thickest portion of the SHP 1 is 0.2 mm (upper limit: 0.2 mm, lower limit: 0.16 mm). Note that these numerical values ​​are design values ​​for this embodiment, but considering tolerances and the like, preferred upper and lower limit dimensions are listed in parentheses. However, the sheet-shaped heat pipe according to the present invention is not limited to these numerical values.

[0025] Here, the assembly method (manufacturing method) of the SHP1 will be outlined. A stainless steel plate is drawn to form the heat dissipation plate 2 and the heat reception plate 3. Next, the wick 4 is placed in the receiving portion 13 of the heat reception plate 3 and temporarily attached to the heat reception plate 3. Next, the heat dissipation plate 2 and the heat reception plate 3 are overlapped. At this time, the first columnar portion 8 is inserted into the slits 15A to 15D of the wick 4, and the second columnar portion 9 presses the wick 4 to prevent it from lifting off the heat reception plate 3. Next, the outer periphery 5 of the heat dissipation plate 2 and the outer periphery 6 of the heat reception plate 3 are joined, forming an internal space S between the heat dissipation plate 2 and the heat reception plate 3. The abutment surface 11 of the first columnar portion 8 is joined to the bottom surface 10 of the heat reception plate 3, the clamping surface 11 of the second columnar portion 9 is joined to the wick 4, and the wick 4 is joined to the bottom surface 10 of the heat reception plate 3. Although not shown, nozzles are formed on the heat dissipation plate 2 and the heat reception plate 3, and a working fluid such as pure water is injected into the internal space S through the nozzles to degas the internal space S. The base end of the nozzle is then sealed by welding, and the nozzle is then cut and removed. The location and number of nozzles can be determined appropriately taking into account the size and shape of the SHP1.

[0026] Next, the operation and effect of the SHP1 configured as described above when installed in equipment will be described. The upper side of FIG. 4 represents one end of the SHP1, and the lower side represents the other end of the SHP1. The heat source P of the installed equipment is thermally connected to one end of the bottom surface 10 of the heat-receiving plate 3 of the SHP1. Heat from the heat source P is transferred to the bottom surface 10, evaporating the liquid-phase working fluid in the gap S1, and the gas-phase working fluid flows through the vapor passage S2 (including the slit portion 15) toward the other end of the SHP1. As the working fluid flows through the vapor passage S2, heat is gradually dissipated from the heat dissipation plate 2, causing the working fluid to condense as it moves away from the heat source P, resulting in the working fluid becoming liquid. The slit portion 15 is not formed at the farthest end 16 of the wick 4, and the wick 4 is connected to the farthest end 16. The liquid-phase working fluid generated near the farthest end 16, where condensation of the working fluid occurs frequently, moves through the gap S1 toward one end due to the capillary force of the wick 4, and moves to the position of the heat source P. In this way, heat is transported by the working fluid inside the SHP 1, cooling the heat source P and mitigating the temperature rise of the equipment.

[0027] As described above, the SHP1 of this embodiment has an internal space S formed between the heat dissipation plate 2 and the heat reception plate 3. The internal space S is filled with the wick 4 and working fluid, and the wick 4 has slits 15A to 15D extending from the vicinity of the heat source P. Therefore, even if the SHP1 is formed thin, the slits 15A to 15D serve as vapor passages S2, and sufficient vapor passages S2 through which the gas-phase working fluid flows can be secured. As a result, the working fluid circulates well in the internal space S, ensuring reliable heat transport.

[0028] Furthermore, in the SHP1 of this embodiment, first column sections 8 and second column sections 9 are formed on the heat dissipation plate 2, protruding toward the heat receiving plate 3, with the first column sections 8 abutting against the heat receiving plate 3 and the second column sections 9 abutting against the wick 4. The first column sections 8 prevent the SHP1 from collapsing when degassing, and can prevent the SHP1 from expanding due to a rise in temperature in the internal space S. Furthermore, the second column sections 9 can prevent the wick 4 from floating up or shifting position.

[0029] Furthermore, in the SHP1 of this embodiment, the first columnar portion 8 is formed to be longer than the second columnar portion 9. Therefore, the first columnar portion 8 can be arranged in a portion where the wick 4 is not arranged or in the slit portions 15A to 15D, and the contact surface portion 11 of the first columnar portion 8 can be brought into contact with the heat receiving plate 3. Furthermore, the second columnar portion 9 can be arranged in a portion where the wick 4 is arranged, and the clamping surface portion 12 of the second columnar portion 9 can be brought into contact with the wick 4.

[0030] Furthermore, in the SHP1 of this embodiment, the area of ​​the wick 4 is larger than the area of ​​the slit portions 15A to 15D. This ensures that the gap S1 formed in the wick 4 is sufficient, allowing the liquid-phase working fluid to flow by capillary force. As a result, the working fluid circulates well in the internal space S, ensuring reliable heat transport.

[0031] Furthermore, in the SHP 1 of this embodiment, the slit portions 15A to 15D do not overlap with the heat source P that is thermally connected to the SHP 1. That is, since the wick 4 is disposed in the internal space S of the heat-receiving plate 3 that is thermally connected to the heat source P, the liquid-phase working fluid can be made to flow through the gap S1 formed in the wick 4 and reach the position where it is thermally connected to the heat source P.

[0032] Furthermore, in the SHP1 of this embodiment, the thickness M of the wick 4 is 0.035 mm to 0.055 mm, the distance L1 between the flat portion 7 of the heat dissipation plate 2 and the bottom surface portion 10 of the heat reception plate 3 in the slit portions 15A to 15D is 0.135 mm to 0.145 mm, and the distance L2 between the flat portion 7 and the wick 4 is 0.085 mm to 0.105 mm. Therefore, by forming the heat dissipation plate 2 and the heat reception plate 3 to, for example, 0.03 mm, the thickness T of the thickest portion of the SHP1 can be formed to be as thin as 0.2 mm or less. Furthermore, even when the thickness T of the thickest portion of the SHP1 is 0.2 mm or less, sufficient heat transport can be achieved.

[0033] Furthermore, in the SHP 1 of this embodiment, the slits 15A-15D are not formed at the farthest end 16 of the wick 4, which is the farthest from the heat source P thermally connected to the SHP 1, and the wick 4 is connected to the farthest end 16. Therefore, the working fluid that has condensed and become liquid near the farthest end 16 can be made to flow in the direction of the heat source P by the capillary force of the wick 4.

[0034] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the external shape of the SHP1 may be changed to a different external shape that corresponds to the internal shape of the device in which the SHP1 is installed. [Explanation of symbols]

[0035] 1 SHP (Sheet Heat Pipe) 2 Heat dissipation plate (first plate) 3 Heat receiving plate (second plate) 4. Wick (capillary structure) 8 First Pillar 9 Second pillar 11 Contact surface part 12 Clamping surface part 15A slit section 15B Slit section 15C Slit section 15D slit section 16 Farthest end L1: Distance between the flat portion 7 and the bottom surface portion 10 L2 Distance between flat part 7 and wick 4 M Wick 4 Thickness P heat source S interior space S1 void S2 Steam passage T Thickness of the thickest part of SHP1

Claims

1. A sheet-shaped heat pipe having an internal space formed between a first plate and a second plate, A capillary structure and a working fluid are sealed in the internal space, The sheet-shaped heat pipe is characterized in that the capillary structure has a slit portion extending from the vicinity of the heat source.

2. The first plate is formed with a first pillar portion and a second pillar portion protruding toward the second plate, the first pillar portion abuts against the second plate, The sheet-type heat pipe according to claim 1 , wherein the second pillar portion abuts against the capillary structure.

3. 3. The sheet-shaped heat pipe according to claim 2, wherein the first columnar portion is formed longer than the second columnar portion.

4. 2. The sheet-shaped heat pipe according to claim 1, wherein the area of ​​the capillary structure is larger than the area of ​​the slit portion.

5. The sheet-shaped heat pipe according to claim 1 , wherein the slit portion does not overlap with a heat source thermally connected to the sheet-shaped heat pipe.

6. the thickness of the capillary structure is 0.035 mm to 0.055 mm; a distance between the flat portion of the first plate and the bottom surface portion of the second plate in the slit portion is 0.135 mm to 0.145 mm; 2. The sheet-shaped heat pipe according to claim 1, wherein the distance between the flat portion and the capillary structure is 0.085 mm to 0.105 mm.

7. 2. The sheet-shaped heat pipe according to claim 1, wherein the slit portion is not formed at the farthest end of the capillary structure that is farthest from the heat source thermally connected to the sheet-shaped heat pipe, and the capillary structure is connected.

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