WO2008020668A1

WO2008020668A1 - Thermal switch

Info

Publication number: WO2008020668A1
Application number: PCT/KR2007/000853
Authority: WO
Inventors: Sun Kyu Lee; Su Heon Jeong; Hee Gon Moon; Wataru Nakayama
Original assignee: Gwangju Institute Of Science And Technology
Priority date: 2006-08-16
Filing date: 2007-02-16
Publication date: 2008-02-21
Also published as: KR100780838B1

Abstract

The present invention relates to a thermal switch, particularly a thermal switch that improves heat transfer efficiency and allows easy control form opening/closing a thermal connection through heat transfer fluid by supplying heat transfer fluid stored or supplied in a fluid storage channel to a tunnel or a switching channel to allow the heat transfer fluid opened to the upper part of the switching channel to be in surface contact with a panel to transfer heat. The present invention provides thermal switch controlling heat transfer between a heat source and a heat sink, which includes: a main panel; a groove-shaped fluid storage channel formed on the downside of the main panel, and containing or supplied with heat transfer fluid; a tunnel formed on the upside of the main panel, connected with the fluid storage channel, and supplied with the heat transfer fluid from the fluid storage channel; and an air discharge channel formed on the upside of the main panel and connected with the tunnel to form an air passage. Further, the thermal switch controls heat transfer between the heat source and heat sink by adjusting a level of the heat transfer fluid in the tunnel.

Description

Description THERMAL SWITCH

Technical Field

[1] The present invention relates to a thermal switch, and in particular, a thermal switch that improves heat transfer efficiency and allows easy control of opening/closing a thermal connection through heat transfer fluid by supplying heat transfer fluid that has been stored or supplied in a fluid storage channel to a tunnel or a switching channel to allow the heat transfer fluid exposed to the upper part of the switching channel to contact the surface of a panel to transfer heat. Background Art

[2] Used to control temperature between a high-temperature part and a low-temperature part, thermal switches control heat transfer from the high-temperature part to the low- temperature part by connecting or disconnecting the high-temperature part and the low-temperature part, depending on the using conditions.

[3] In the related art, US Patent Application No. 2006/0066434 (Published on March

30, 2006) discloses a thermal switch that controls heat transfer between a high- temperature part and a lower temperature part using fluid drops.

[4] FIGS. IA and IB show a thermal switch in an OFF-state and an ON-state, respectively, as an example of the related art.

[5] A thermal switch 10 according to the related art includes a first conductive plate 12, a second conductive plate 16, and a spacer 14 maintaining the gap between them. Contact pads 18 are provided on the first conductive pad 12 and a fluid drop 20 is provided on the contact pads 18. The fluid drops 20 are in contact with the contact pads 18 by the surface tension between the fluid drops 20 and the contact pads 18.

[6] The second conductive plate 16 is made of a flexible material to be bendable. When power is supplied to first electrodes 22a attached on the first conductive plate 12 and second electrodes 22b attached on the second conductive plate 16, attraction is generated between the first electrodes 22a and the second electrodes 22b and the downside of the second conductive plate 16 contacts the fluid drops 18, thereby turning on the thermal switch. FIG. IB shows the thermal switch in an ON-state. As a result, the first conductive plate 12 and the second conductive plate 16 are thermally connected. On the other hand, the second conductive plate 16 may be provided with a piezoelectric element instead of the electrodes 22a, 22b to bend.

[7] FIGS. 2A and 2B show another thermal switch in an OFF-state and an ON-state, respectively, as another example of the related art.

[8] A thermal switch 10 shown in FIGS. 2A and 2B includes a first conductive plate 12 and a second conductive plate 16, and contact pads 18 and fluid drops 20 are provided on the first conductive pads 18. The second conductive plate 16 is made of a flexible material and capable of contacting the fluid drops 20 in FIGS. IA and IB; however, in FIGS. 2 A and 2B, the conductive plate 16 moves up and down to be in contact with the fluid drops 20.

[9] These thermal switches are turned on/off to control heat transfer by connecting a first conductive plate and a second conductive plate, but not applicable to two fixed parts.

[10] Further, according to thermal switches of the related art, it was difficult to control heat transfer at specific positions. Specifically, according to thermal switches of the related art, since the thermal connection was achieved by deforming or moving one of the conductive plates, it was difficult to control heat transfer.

[11] Further, according to thermal switches of the related art, since the thermal connections were made at the contact points of the fluid drops with the conductive plates and the contact pads, it was difficult to obtain sufficient heat transfer. Disclosure of Invention Technical Problem

[12] In order to overcome the above problems, it is an object of the invention to provide a panel-shaped thermal switch including a heat source and a heat sink, in which heat transfer between a high-temperature part and a low-temperature part is controlled by supplying heat transfer fluid that has been contained or supplied in a fluid storage channel into a tunnel or a switching channel above the fluid storage channel, and an air discharge channel is provided for the tunnel or the switching channel to allow air to flow as the heat transfer fluid flows up and down.

[13] Further, it is another object of the invention to provide a configuration that effectively controls the supply of heat transfer fluid into a tunnel or a switching channel from a fluid storage channel.

[14] Further, it is a still another object of the invention to provide a thermal switch that allows effective heat transfer through heat transfer fluid between a heat source and a heat sink while preventing the heat transfer fluid from leaking out through an air discharge passage by controlling a contact angle.

[15] Further, it is a still another object of the invention to provide a thermal switch that includes a plurality of tunnels or switching channels for the thermal connection and controls the tunnels or the switching channels to achieve the thermal connections at desired positions. Technical Solution

[16] In order to achieve the above objects, the present invention provides a thermal switch controlling the heat transfer between a heat source and a heat sink, which includes: a main panel; a groove-shaped fluid storage channel formed on the downside of the main panel, and containing or supplied with heat transfer fluid; a tunnel formed on the upside of the main panel, connected with the fluid storage channel, and supplied with the heat transfer fluid from the fluid storage channel; and an air discharge channel formed on the upside of the main panel and connected with the tunnel to form an air passage. Further, the thermal switch controls the heat transfer between the heat source and heat sink by adjusting a level of the heat transfer fluid in the tunnel.

[17] Preferably, the level of the heat transfer fluid in the tunnel is adjusted by an expanding member that is disposed in the fluid storage channel and varies in volume. Accordingly, the expanding member may contain expanding fluid, a phase-variable material or a thermal-expanding material that varies in volume by heat transfer.

[18] According to another embodiment, the level of the heat transfer fluid in the tunnel may be adjusted by a heat transfer fluid controller that adjusts the amount of the heat transfer fluid stored in the fluid storage channel.

[19] Preferably, the transverse cross-section of the air discharge channel may be curved and connected with the upper portion of the tunnel, and the upper portion of the tunnel and the air discharge channel may be coated with a hydrophilic material.

[20] According to another object of the invention, the invention provides a thermal switch controlling the heat transfer between a heat source and a heat sink, which includes: a main panel; a tunnel array including a plurality of tunnels arranged through the main panel from the upside to the downside; a plurality of air discharge channel formed on the upside of the main panel and connected with an upper end of the tunnels at a side of the tunnel array; and a plurality of fluid storage channel formed on the downside of the main panel and supplying heat transfer fluid into the tunnels at a side of the tunnel array. Further, the thermal switch controls heat transfer between the heat source and the heat sink by adjusting the level of the heat transfer fluid in the tunnel.

[21] Preferably, the air discharge channels or the fluid storage channels may be separately controlled to control the heat transfer of the tunnel array.

[22] Further, according to another object of the invention, the invention provides a thermal switch that controlling the heat transfer between a heat source and a heat sink, which includes: a main panel; a fluid storage channel formed in a groove shape on the downside of the main panel, and containing or supplied with heat transfer fluid; a groove-shaped switching channel formed on the upside of the main panel, connected with the upper portion of the fluid storage channel, and divided from the fluid storage channel by a protrusion; and an air discharge channel providing an air discharge passage connected with the switching channel. Further, the thermal switch controls heat transfer between the heat source and the heat sink by adjusting the level of the heat transfer fluid.

[23] Preferably, a triangular protrusion is formed at the connecting portion of the switching channel and the air discharge channel, with a steep slope to the switching channel and a gentle slope to the air discharge channel in order to prevent leakage of the heat transfer fluid from the switching channel to the air discharge channel.

[24] Further, preferably, a burst area is formed opposite to the air discharge channel in the switching channel and a contact angle between the heat transfer fluid and the protrusion in the burst area is larger than an contact angle between the heat transfer fluid and the protrusion in other area, except for the burst area in order for the heat transfer fluid that flows into the switching channel to fill the burst area first.

[25] According to another object of the invention, the invention provides a thermal switch controlling the heat transfer between a heat source and a heat sink, which includes: a main panel; a plurality of unit thermal switches arranged in the main panel; and a plurality of controller controlling a level of heat transfer fluid in the unit switches. Further, the unit switch includes: a groove-shaped fluid storage channel formed on the downside of the main panel, and containing or supplied with the heat transfer fluid; a groove-shaped switching channel formed on the upside of the main panel, divided form the fluid storage channel by a protrusion, and connected with the fluid storage channel; and an air discharge panel connected with the switching channel and providing an air discharge passage.

[26] According to another embodiment of the invention, a cylindrical hydrophilic assistant member having a plurality of protrusions with small grooves longitudinally formed on the outside is inserted in the fluid storage channel.

Advantageous Effects

[27] According to the invention, it is possible to easily control heat transfer between a fixed high-temperature part and a fixed low-temperature part by controlling the movement of the heat transfer fluid using an expanding member that provides pressure. Further, according to the invention, it is possible to accurately control temperature and provide thermal connections to desired positions because an effect from thermal capacity of a high-temperature part is small by thermally separating the high- temperature part from a low-temperature part. Further, according to the invention, it is possible to increase the amount of heat transfer because the heat transfer between a high-temperature part and a low-temperature part is achieved through heat transfer fluid. Brief Description of the Drawings

[28] FIGS. IA and IB show a thermal switch in an OFF-state and an ON-state, respectively, as an example of the related art. [29] FIGS. 2A and 2B show another thermal switch in the OFF-state and the ON-state, respectively, as another example of the related art. [30] FIG. 3 is a perspective view of a thermal switch according to a first preferred embodiment of the invention. [31] FIG. 4 is a cross-sectional view illustrating the thermal switch in the OFF-state according to the first preferred embodiment of the invention. [32] FIG. 5 is a cross-sectional view illustrating the thermal switch in the ON-state according to the first preferred embodiment of the invention. [33] FIG. 6 is a perspective view illustrating the connection between a tunnel and an air discharge channel of the thermal switch in the ON-state according to the first preferred embodiment of the invention. [34] FIGS. 7 A and 7B are views illustrating changes in a contact angle according to movement conditions of the heat transfer fluid inside the tunnel of the thermal switch in the ON-state according to the first preferred embodiment of the invention. [35] FIG. 8 is a perspective view showing the configuration of a thermal switch including a plurality of tunnels according to a second preferred embodiment of the invention. [36] FIGS. 9A to 9C is a view illustrating a method of controlling the thermal switch according to the second preferred embodiment of the invention. [37] FIG. 10 is a cross-sectional view of a thermal switch according to a third preferred embodiment of the invention. [38] FIG. 11 is a cross-sectional view of a thermal switch according to a fourth preferred embodiment of the invention. [39] FIG. 12 is a perspective view of a thermal switch according to a fifth preferred embodiment of the invention. [40] FIG. 13 is a perspective view showing the bottom of the thermal switch according to the fifth preferred embodiment of the invention. [41] FIG. 14 is a perspective view illustrating the connection of a switching channel and an air discharge channel of the thermal switch according to the fifth preferred embodiment of the invention.

[42] FIG. 15 is a cross-sectional view taken along the line A-A' of FIG. 14.

[43] FIG. 16 is a perspective view of a switching channel having a bust area of the thermal switch according to the fifth preferred embodiment of the invention. [44] FIGS. 17A and 17B are cross-sectional views taken along the lines B-B' and C-C, respectively. [45] FIGS. 18A and 18B are views illustrating heat transfer fluid that fills up in FIGS.

17A and 17B. [46] FIG. 19 is a view illustrating a process to turn on the thermal switch according to the fifth preferred embodiment of the invention by supplying heat transfer fluid to the switching channel.

[47] FIG. 20 is a view illustrating a process to turn off the thermal switch according to the fifth preferred embodiment of the invention by discharging heat transfer fluid out of the switching channel.

[48] FIG. 21 is a perspective view of a thermal switch according to a sixth preferred embodiment of the invention.

[49] FIG. 22 is a plan view illustrating control of the thermal switch according to the sixth preferred embodiment of the invention.

[50] FIG. 23 is a perspective view of a hydrophilic assistant member according to a preferred embodiment of the invention.

[51] FIG. 24 is a view showing the hydrophilic assistant member equipped in the fluid storage channel of a thermal switch according to a preferred embodiment of the invention. Best Mode for Carrying Out the Invention

[52] Preferred embodiments of the invention will be described hereafter in detail with reference to the accompanying drawings. Describing the invention herein, when it is considered that detailed description about related known configurations or functions makes the aspects of the invention unclear, the detailed description may be omitted. Further, preferred embodiments of the invention are described hereafter, but it will be apparent to those skilled in the art that various modifications and changes may be made thereto without departing from the scope and spirit of the invention.

[53] FIG. 3 is a perspective view of a thermal switch according to a first preferred embodiment of the invention, FIG. 4 is a cross-sectional view illustrating the thermal switch according to the first preferred embodiment of the invention in the OFF-state, and FIG. 5 is a cross-sectional view illustrating the thermal switch according to the first preferred embodiment of the invention in the ON-state.

[54] A thermal switch 100 according to the first preferred embodiment of the invention includes a first panel 120 that is a heat source or a heat generating body, or connected with them and a second panel 122 that is a heat sink or a cooling part, or connected with them. The thermal switch 100 controls heat transfer between the first panel 120 and the second panel 122 by opening/closing a thermal connection between the first panel 120 and the second panel 122. In detail, the first panel 120 is a high-temperature part and the second panel 122 is a low-temperature part, and the thermal switch 100 controls heat transfer between the first panel 120, the high-temperature part, and the second pane 122, the low-temperature part. However, in other embodiments of the invention, the first panel 120 may be a low-temperature part and the second panel 122 may be a high-temperature part.

[55] Accordingly, the thermal switch 100 according to a preferred embodiment of the invention includes a flat main panel 102, a tunnel 104 formed through the main panel 102 from the upside to the downside, a fluid storage channel 108 storing heat transfer fluid 112 under the tunnel 104, an expanding member 110 disposed in the fluid storage channel 108, and an air discharge channel 106 formed in connection with the upper portion of the tunnel 104. As the expanding member 110 expands, the heat transfer fluid 112 stored in the fluid storage channel 108 ascends through the tunnel 104 and contacts the first panel 120, which thermally connects the first panel 120 with the second panel 122.

[56] It is preferable to make the main panel 102 of a material with a low heat transfer coefficient to prevent heat transfer between the first panel 120 and the second panel 122 through the main panel 102 after the main panel 102 is positioned between the first panel 120 and the second panel 122. The main panel 102 may be made of glass, Priex Glass, quartz, silicon, or polymer and an insulating layer may be provided on one of the upside and downside of the main panel 102 to prevent heat transfer through the main panel 102.

[57] The main panel 102 may be manufactured by a mechanical process and by etching a semiconductor wafer using a manufacturing method for MEMS (Micro Electro Mechanical Systems) as well.

[58] The tunnel 104 of the main panel 102 is formed through the main panel 102 from the upside to the downside, a part of the edge of the upper portion of the tunnel 104 is adjacent to the air discharge channel 106, and the lower opening of the tunnel 104 is connected with the fluid storage channel 108. The heat transfer fluid stored in the fluid storage channel 108 flows through the tunnel 104.

[59] The air discharge channel 106 is formed to allow the air inside the tunnel 104 to be discharged outside as the heat transfer fluid 112 is filled into the tunnel 104. When the air discharge channel 106 is not provided, the heat transfer fluid 112 is not completely filled in the upper portion of the tunnel 104; therefore, it is difficult to achieve the thermal connection between the first panel 120 and the second panel 122. In detail, in order to overcome the problem that the heat transfer fluid 112 cannot reach the upside of the tunnel 104 due to the air at the upper portion in the tunnel 104, the air discharge panel 106 is formed in connection with the upper portion of the tunnel 104 such that the air inside the tunnel 104 can be discharged outside by the heat transfer fluid 112 moving up. The air discharge channel 106 is connected with the upper opening of the tunnel 104, so that the heat transfer fluid does not flows into the air discharge channel 106 by increasing the contact angle of the heat transfer fluid 112, which is described later. [60] The fluid storage channel 108 is connected with the lower opening of the tunnel

104. The heat transfer fluid 112 is stored in the fluid storage channel 108.

[61] As described above, the main panel 102 of the thermal switch 100 preferably has a low heat transfer coefficient, but the heat transfer fluid preferably has a high heat transfer coefficient. Accordingly, the heat transfer fluid 112 may be a liquid metal or an aqueous solution containing water. The liquid metal may be a metal, such as mercury, gallium, or indium, or a gallium-indium alloy.

[62] The expanding member 110 is provided in the fluid storage channel 108 and expanding fluid 114 is contained in the expanding member 110. The expanding member 110 is adjusted in volume by an expansion controller 116. The expansion controller 116 may include a cylinder or a pump and controls the volume of the expanding member 110 by adjusting the amount of the expanding fluid 114 to supply into the expanding member 110. The expanding member 110 is made of an elastic material such as a rubber. On the other hand, the expanding fluid 114 is a gas or liquid. It is preferable to provide a seal 118, which closes an opening at a side, in the opening of the fluid storage channel 108 with a part of the expanding member exposed outside to prevent leakage of the heat transfer fluid 112.

[63] The operation of the thermal switch 100 having the above configuration is described hereafter.

[64] The OFF-state of the thermal switch 100 herein means that the first panel 120 and the second panel 122 are not thermally connected and the ON-state means that the first panel 120 and the second panel 122 are thermally connected through the heat transfer fluid 112.

[65] Before the expanding member 110 expands as shown in FIG. 4, the heat transfer fluid 112 is not in contact with the first panel 120; therefore, the thermal switch 100 is in the OFF-state. As the expanding member 110 expands from the above non- expansion state by the expansion controller 116 as shown in FIG. 5, the heat transfer fluid 112 stored in the fluid storage panel 108 moves to the upper portion of the tunnel 104 and contacts the first panel 120. The air in the tunnel 104 is discharged outside through the air discharge channel 106 and the heat transfer fluid 112 can contact the first panel 120 accordingly. Since the fluid storage channel 108 is open at the bottom, the heat transfer fluid 112 at the lower portion is in contact with the second panel 122, and, accordingly, the first panel 120 is thermally connected with the second panel 122 through the heat transfer fluid 112.

[66] In the above embodiment, the heat transfer fluid 112 should not leak through the air discharge channel 106 when the thermal switch 100 is in the ON-state, which is possible by the connection of the tunnel 104 and the air discharge channel 106.

[67] FIG. 6 is a perspective view illustrating the connection between the tunnel and air discharge channel of the thermal switch according to the first preferred embodiment of the invention and FIG. 7 is a view illustrating changes in contact angle according to movement conditions of the heat transfer fluid inside the tunnel of the thermal switch according to the first preferred embodiment of the invention.

[68] When a fluid drop is in contact with the surface of a solid, a contact angle is formed on the contact surface of the fluid drop and the solid. The contact angle is an angle formed between the free surface of the fluid drop and the surface of the solid. Even though the fluid drop is increased in size by the surface tension of the fluid drop, the contact angle increases without increase in the contact area between the fluid drop and the surface of the solid and the amount of the fluid drop can be increased. When the contact angle exceeds a critical value, the surface tension of the fluid drop cannot withstand. As a result, the contact area between the fluid drop and the surface of the solid increases and the fluid drop becomes stable. The maximum of the contact angle between the fluid drop and the surface of the solid depends on the surface tension of the fluid drop. For example, a fluid drop is in contact to the surface of a solid, mercury forms a drop that is closer to a sphere than water, because the mercury is larger in surface tension than water.

[69] As shown in FIG. 6, the upper portion of the tunnel 104 is a circular shape and connected with an air discharge channel 106 having a round cross-section on a main panel 102. Referring to FIG. 7 A, the contact angle of heat transfer fluid 112 and the tunnel 104 is θ in the OFF-state. On the other hand, referring to FIG. 7B, a reference surface inclination is small at the contact point of the air discharge channel 106 and the tunnel 104 as compared with the wall of the tunnel 106, so that the contact angle θ of the heat transfer fluid 112 is smaller than the contact angle θ of FIG. 7 A at the contact point of the air discharge channel 106 and the tunnel 104. Accordingly, the heat transfer fluid 112 does not flow into the air discharge channel 106 and can contact the first panel 120 as the surface of the heat transfer fluid 112 ascends.

[70] The thermal switch 100 having one tunnel 104 is described above by way of example, but the thermal switch 100 according to the invention may have a plurality of arrays of tunnel 104, and according to this configuration, it is possible to control thermal connection portions between the first panel 120 and the second panel 122.

[71] It is preferable to coat the wall and the upper portion of the tunnel 104 and the air discharge channel 106 with a hydrophobic material to contact the heat transfer fluid 110 to the downside of the first panel 120 on the main panel 102 with a large contact angle at the wall and the upper portion of the tunnel 104.

[72] FIG. 8 is a perspective view showing the configuration of a thermal switch having a plurality of tunnels according to the second preferred embodiment of the invention. FIG. 9 is a view illustrating a method of controlling the thermal switch according to the second preferred embodiment of the invention.

[73] According to the embodiment shown in FIG. 8, tunnels 104 are formed in a 3x3 array, a group of air discharge channels 106 and a group of fluid storage channels 108 are arranged longitudinally and transversely, respectively. Reference characters 'a', 'b', and 'c' are given to the air discharge channels of the group of air discharge channels 106 from the left and 'x', 'y', and 'z' are given to the fluid storage channels of the group of fluid storage channels 108 from above, respectively. Therefore, in the tunnels 104, according to the order of the given reference characters, the left uppermost tunnel is referred by '104ax' and the right lowermost tunnel is referred by '104cz'. Referring to FIG. 8, the tunnel 104 is arranged in the 3x3 array by way of example, but the arrangement of the tunnel 104 is not limited thereto in other embodiments of the invention and may be modified in a variety of ways according to the conditions of the embodiments.

[74] An expanding member 110 provided in the fluid storage channels 108 is controlled by separate expansion controllers (not shown) and the air discharge channels 106 are controlled to open and close. It is possible to control the transversely arranged tunnels by controlling the expanding members 110. Further, it is possible to control the longitudinally arranged tunnels by controlling the air discharge channel 106 to open and close. This is because the heat transfer fluid 112 cannot contact the first panel 120 on the main panel 102 for the thermal connection even though it ascends through the tunnel 104, unless the air is not discharged through the air discharge channel 106.

[75] As shown in FIG. 9A, with the left air discharge channel 106a open and the right air discharge channels 106b, 106c closed, as only the expanding member HOx expands, only the left uppermost tunnel 104ax comes into the ON-state.

[76] In the above condition, as shown in FIG. 9B, as the center and right air discharge channels 106b, 106c are opened, the center and right uppermost tunnels 104bx, 104cx come into the ON-state as well.

[77] In addition, as shown in FIG. 9C, as the left and center air discharge channels 106a,

106b are closed and the center expanding member HOy and the lower expanding member 11Oz are expanded, the center and lower tunnels 104c, 104z on the right line come into the ON-state as well.

[78] A method of controlling the ON/OFF of the tunnel array in sequence was described with reference to FIGS. 9 A to 9C; however, according to the second preferred embodiment of the invention, it is possible to control a desired tunnel in the group of tunnels 104 by controlling the groups of air discharge channels 106 and expanding members 110.

[79] Further, the group of air discharge channels 106 and the group of expanding members 110 are arranged longitudinally and transversely in FIGS. 9 A to 9C, but the groups of air discharge channels 106 and expanding members 110 may be arranged in the same direction in other embodiments of the invention.

[80] In the above embodiment, the thermal switch 100 is controlled into the ON/OFF state by controlling the volume of the expanding members of the group of expanding members 110 using the expansion controller 116, but the group of expanding members 110 may be controlled by a method that is described below.

[81] FIG. 10 is a cross-sectional view of a thermal switch according to the third preferred embodiment of the invention.

[82] Referring to FIG. 10, a solid phase-variable material 130 is provided at a side of a fluid storage channel 108 of a thermal switch 110 and connected with an end of an expanding member 110. The phase- variable material 130 is in contact with a first panel 120 and supplied with heat from the first panel 120. Accordingly, as the phase-variable material 130 is vaporized by the heat transferred from the first panel 120 and delivered into the expanding member 110, the expanding member 110 expands and the thermal switch 100 is turned on. An insulating layer 132 is provided under the phase-variable material 130 to prevent thermal contact between the phase- variable material 130 and a second panel 122.

[83] According to the third embodiment of the invention, it is possible to automatically control the thermal connection of the first panel 120 and the second panel 122 depending on temperature of the first panel 120.

[84] Further, other than the phase-variable material 130, various thermal-expanding materials that expand by heat without phase changes, instead of the phase- variable material 130. When a thermal-expanding material is used, it is filled in the expanding member 110. Accordingly, as the thermal-expanding material expand by the heat transferred from the first pane 120, the expanding member 110 expands such that the thermal switch 100 is turned on. On the contrary, when the thermal-expanding material is cooled, the thermal switch 100 is turned off.

[85] In the above embodiment, the level of the heat transfer fluid 112 in the fluid storage channel 108 was changed by adjusting the volume of the expanding member 110. However, in other embodiments of the invention, it is possible to adjust the level of the heat transfer fluid 112 ascending through the tunnel 104 by adjusting the amount of the heat transfer fluid 112 itself that is stored in the fluid storage channel 108, without providing the expanding member 110.

[86] FIG. 11 is a cross-sectional view of a thermal switch according to the fourth preferred embodiment of the invention. A thermal switch according to the fourth preferred embodiment of the invention includes a flat main panel 102, a tunnel 104 formed through the main panel 102 from the upside to the downside, a fluid storage channel 108 storing heat transfer fluid 112 under the tunnel 104, a heat transfer fluid supply pipe 142 allowing the heat transfer fluid 112 to be supplied into the fluid storage channel 108, a heat transfer fluid controller 140 adjusting the amount of the heat transfer fluid 112 stored in the fluid storage channel 108 by supplying or discharging the heat transfer fluid 112 through the heat transfer fluid supply pipe 142.

[87] The heat transfer fluid controller 140 includes a pump or a cylinder and controls the level of the heat transfer fluid 112 in the tunnel 104 by adjusting the amount of the heat transfer fluid 112 that is stored in the fluid storage channel 108. Therefore, according to the fourth preferred embodiment of the invention, it is possible to control the ON/ OFF of the thermal switch 100 by adjusting the amount of the heat transfer fluid 112 without a specific expanding member.

[88] This configuration is applicable to the thermal switch in which the tunnels 104 are arranged in an array, as in the second preferred embodiment of the invention.

[89] In the above embodiment, the heat transfer fluid in the fluid storage channel 108 ascends through the tunnel 104 and contacts the first panel at the upper portion of the thermal switch 100, the tunnel 104 is connected with the air discharge channel 106 to allow the air to flow and the heat transfer fluid to form a stable contact angle at the upper portion of the tunnel 104.

[90] The configuration of a thermal switch 100 in which the heat transfer fluid contacts a first panel at the upper portion of the thermal switch in a wide line type is described hereafter. According to this embodiment, a switching channel, instead of the tunnel 104, is formed above the fluid storage channel 108.

[91] FIG. 12 is a perspective view of a thermal switch according to the fifth preferred embodiment of the invention and FIG. 13 is a perspective view showing the bottom of the thermal switch according to the fifth preferred embodiment of the invention.

[92] A thermal switch 300 according to the fifth embodiment of the invention is provided between a first panel (not shown) that is a heat source or heat generating body, or connected with them and a second panel (not shown) that is a heat sink or a cooling part, or connected with them. The upside of the thermal switch 300 contacts the first panel and the downside contacts the second panel, so that heat transfer between the first panel and the second panel is controlled by opening/closing the thermal connection between the first panel and the second panel. Alternatively, the functions of the first panel and the second panel may be changed in the embodiments of the invention.

[93] Accordingly, the thermal switch according to the preferred embodiments of the invention includes a flat main panel 310, a fluid storage channel 320 formed on the bottom of the main panel 310 and storing heat transfer fluid, a switching channel 330 formed on the upside of the main panel 310 above the fluid storage channel 320 and connected with the fluid storage channel 320, and an air discharge channel 340 formed adjacent to an end of the switch channel 330. The switching channel 330 in the embodiments of the invention may be formed in a rectangular or elliptic line type. It is preferable to form the switching channel 330 into a rectangular or elliptic shape with both ends rounded.

[94] When the thermal switch according to embodiments of the invention is turned on, heat transfer fluid that is stored in the fluid storage channel 320 or supplied through the fluid storage channel 320 flows into the switch channel 330 and contacts the first panel on the main panel 310, thereby thermally connecting the first panel with second panel.

[95] The fluid storage channel 320 is a trough formed on the bottom of the main panel

310. The heat transfer fluid is supplied into the fluid storage channel 320. The configuration that makes the heat transfer fluid stored in the fluid storage channel 320 ascend to the switching channel 330 includes the configurations of the first, third, and fourth embodiments.

[96] The switching channel 330 is formed on the upside of the fluid storage channel 320 and is preferably longitudinally long. The switching channel 330 and the fluid storage channel 320 is separated by a protrusion 332 protruding from the wall to the center to divide up and down the switching channel 330 and the fluid storage channel 320. An end of the switching channel 330 is connected with the air discharge channel 340 through a connecting portion 334 and a burst area 336 is formed at the other end.

[97] On the other hand, the fluid storage channel 320 is preferably made of a hydrophilic material or coated with a hydrophilic material to effectively store the heat transfer fluid, and the switching channel 330 and the air discharge channel 340 are preferably made of a hydrophobic material or coated with a hydrophobic material.

[98] First, the configuration of the air discharge channel 340 and the connection of the air discharge channel 340 and the switching channel 330 are described.

[99] FIG. 14 is a perspective view illustrating the connection of the switching channel and the air discharge channel on the thermal switch according to the fifth preferred embodiment of the invention and FIG. 15 is a cross-sectional view taken along the line A-AOf FIG. 14.

[100] The air discharge channel 340 allows the air in the switching channel 330 as the heat transfer fluid flows into the switching channel 330, whereas it functions as a passage allowing outside air to flow into the switching channel 330.

[101] The connecting portion of the air discharge panel 340 and the switching channel

330 is preferably rounded and a substantially triangular protrusion 334 is formed at the contact point of the air discharge channel 340 and the switching channel 330, as shown in FIG. 15.

[102] Referring to FIG. 15, a steep slope is formed from the triangular protrusion 334 to the wall of the switching channel 330 and a gentle slope is formed from the triangular protrusion 334 to the air discharge channel 340. Therefore, when the heat transfer fluid ascends through the switching channel 330, the contact angle is decreased because the angle between the heat transfer fluid and the air discharge channel 340 at the end of the triangular protrusion 334 is small. Accordingly, the heat transfer fluid in the switching channel 330 cannot not flow into the air discharge channel 340, so that it can sufficiently function as a thermal switch minimizes any malfunction.

[103] The configuration of the burst area 336 is described next.

[104] FIG. 16 is a perspective view of the switching channel having a burst area according to the fifth preferred embodiment of the invention, FIGS. 17 A and 17B are cross-sectional views taken along the lines B-B' and C-C of FIG. 16, respectively, and FIGS. 18A and 18B are views illustrating the heat transfer fluid ascending in FIGS. 17A and 17B.

[105] The burst area 336 is formed as described above at a side of the switching channel

330. A protrusion 332 forms a step 338 at other portion, except for the burst area 336 in the switching channel 330. The protrusion 332 forms a gentle curved or oblique surface in the burst area 336 and connected to the upper portion of the switching channel 330.

[106] Referring to FIG. 17A, the protrusion 332 dividing the fluid storage channel 320 and the switching channel 330 forms a gentle curved or oblique surface in the burst area 336 and is connected to the upper portion of the switching channel 330. On the other hand, referring to FIG. 17B, the upper portion of the protrusion 332 forms the step 338 at other portion, except for the burst area 336 in the switching channel 330. Therefore, when the heat transfer fluid 122 ascends to the fluid storage channel 320 through the switching channel 330, it reaches the critical contact angle first in the burst area 336 as compared with the other regions, which is illustrated in FIGS. 18A and 18B. Comparing FIGS. 18A and 18B, the contact angle 180°-α of the heat transfer fluid 122 at the protrusion 332 in the burst area 336 is larger than the contact angle 180°-α at the step.

2

[107] Accordingly, the heat transfer fluid 122 ascending to the switching channel 330 fills first the burst area 336 where it reaches first the critical contact angle, and then fills the switching channel 330 through the burst area 336.

[108] FIG. 19 is a view illustrating a process that the thermal switch according to the fifth preferred embodiment of the invention is turned on by supplying the heat transfer fluid into the switching channel and FIG. 20 is a view illustrating a process that the thermal switch according to the fifth preferred embodiment of the invention is turned off by discharging the heat transfer fluid out of the switching channel.

[109] Referring to FIG. 19, as the heat transfer fluid 322 is supplied into the fluid storage channel 320, it fills the burst area 336 first and then flows to the other area in the switching channel 330. Referring to FIG. 20, as the heat transfer fluid 322 is discharged out of the fluid storage channel 320, it is discharged out of the switching channel 330 and finally the burst area 336. This process is made, as described, because the heat transfer fluid 322 fills the burst area 336 first by increasing the contact angle between the heat transfer fluid 322 and the protrusion 332 in the burst area 336. On the other hand, the reason why the heat transfer fluid 322 does not flow into the air discharge channel 340 after filling the switching channel 330 is that, as described, the triangular protrusion 334 is formed at the interface of the switching channel 330 and the air discharge channel 340.

[110] One thermal switch 300 is described by way of example in the above embodiment, but a plurality of thermal switches 300 may be provided.

[I l l] FIG. 21 is a perspective view of a thermal switch according to the sixth preferred embodiment of the invention and FIG. 22 is a plan view illustrating the control of the thermal switch according to the sixth preferred embodiment of the invention.

[112] Referring to FIG. 21, a thermal switch 400 according to the sixth preferred embodiment of the invention includes a plurality of thermal switches 300 arranged in a main panel 210. The thermal switch 400 can be entirely controlled, but it is preferable to provide a controller 420 for each of the thermal switches 300 for effective use, as shown in FIG. 22. The controller 420 adjusts the level of the heat transfer fluid of the thermal switch 300 through a control line 430 connected to the fluid storage channel 320. According to a method of controlling the level of the heat transfer fluid, as described above, the volume of an expanding member provided in the fluid storage channel 320 is adjusted by the controller 420 or the heat transfer fluid is supplied to or discharged out of the fluid storage channel 320 by the controller 420.

[113] A configuration that effectively stores the heat transfer fluid in the fluid storage channels 108, 320 of the thermal switches described in the above embodiments is described hereafter.

[114] The heat transfer fluid should be uniformly filled in the fluid storage channels 108,

320 for normal operation and easy control of the thermal switches 100, 300. Accordingly, it is profitable for the fluid storage channels 108, 320 to have high hy- drophilicity and a hydrophilic coating was applied to the fluid storage channels 108, 320 in the related art. In addition to the above-mentioned hydrophilic coating in the related art, in the embodiments of the invention, a hydrophilic assistant member is provided in the fluid storage channels 108, 320 to effectively supply and store the heat transfer fluid in the fluid storage channels 108, 320.

[115] FIG. 23 is a perspective view of a hydrophilic assistant member provided in a fluid storage channel of a thermal switch according to preferred embodiments of the invention and FIG. 24 is a view illustrating the hydrophilic assistant member provided in a fluid storage channel of a thermal switch according to the preferred embodiments of the invention.

[116] A hydrophilic assistant member 500 is formed into a circular or polygonal cylindrical shape to provide in the fluid storage channels 108, 320 and has a plurality of protrusions 510 with small grooves longitudinally formed on the surface. A hydrophilic coating is applied to the surface of the hydrophilic assistant member 500. Therefore, when the hydrophilic assistant member 500 is disposed in a fluid storage channel 520, the heat transfer fluid travels to the end through the grooves of the protrusions 510 by capillary action. Further, a gap is formed between the fluid storage channels 108, 320 and the hydrophilic assistant member 500; therefore, the heat transfer fluid is effectively stored in the fluid storage channels 108, 320.

[117] Although the preferred embodiments of the invention have been disclosed for illustrative purposes of spirit of the invention, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and sprit of the invention. Therefore, it should be understood that the above embodiments and the accompanying drawings are not limitative, but illustrative for spirit of the invention, and the spirit of the invention is not limited to the embodiments and accompanying drawings. The scope of the invention should be construed by the appended claims and all spirits within equivalences of the claims are intended to be embraced by the claims. Industrial Applicability

[118] The present invention relates to a thermal switch that is used to control the temperature between a high-temperature part and a low-temperature part, which is applicable for various applications with high industrial applicability, because according to the improved configuration of the invention it is possible to effectively control heat transfer between the high-temperature part and the low-temperature part and increase the amount of the heat transfer as well.

Claims

[1] A thermal switch that controls heat transfer between a heat source and a heat sink, comprising: a main panel; a groove-shaped fluid storage channel formed on the downside of the main panel, and containing or supplied with heat transfer fluid; a tunnel formed on the upside of the main panel, connected with the fluid storage channel, and supplied with the heat transfer fluid from the fluid storage channel; and an air discharge channel formed on the upside of the main panel and connected with the tunnel to form an air passage, wherein heat transfer is controlled between the heat source and heat sink by adjusting a level of the heat transfer fluid in the tunnel.

[2] The thermal switch according to claim 1, wherein the level of the heat transfer fluid in the tunnel is adjusted by an expanding member that is disposed in the fluid storage channel and varies in volume.

[3] The thermal switch according to claim 2, wherein the expanding member contains expanding fluid, and the volume of the expanding member is adjusted by adjusting the amount of the expanding fluid to supply using an expansion controller

[4] The thermal switch according to claim 2, wherein the expanding member includes one of a phase-variable material and a thermal-expanding material that are changed in volume by heat transfer from the heat source to adjust the volume.

[5] The thermal switch according to claim 1, wherein the level of the heat transfer fluid in the tunnel is adjusted by a heat transfer fluid controller that adjusts the amount of the heat transfer fluid stored in the fluid storage channel.

[6] The thermal switch according to any one of claims 1 to 5, wherein the transverse cross-section of the air discharge channel is curved and connected with the upper portion of the tunnel.

[7] The thermal switch according to any one of claims 1 to 5, wherein the upper portion of the tunnel and the air discharge channel are coated with hydrophilic material.

[8] The thermal switch according to any one of claims 1 to 5, wherein an insulating layer is provided on one of the upside and downside of the main panel.

[9] A thermal switch that controls the heat transfer between a heat source and a heat sink, comprising: a main panel; a tunnel array including a plurality of tunnels arranged through the main panel from the upside to the downside; a plurality of air discharge channels formed on the upside of the main panel and connected with an upper end of the tunnels at a side of the tunnel array; and a plurality of fluid storage channels formed on the downside of the main panel and supplying heat transfer fluid into the tunnels at a side of the tunnel array, wherein heat transfer is controlled between the heat source and the heat sink by adjusting the level of the heat transfer fluid in the tunnel.

[10] The thermal switch according to claim 9, wherein the level of the heat transfer fluid in the tunnels is adjusted by an expanding member that is disposed in the fluid storage channels and varies in volume.

[11] The thermal switch according to claim 9, wherein the level of the heat transfer fluid in the tunnels is adjusted by a heat transfer fluid controller that controls the amount of the heat transfer fluid stored in the fluid storage channels.

[12] The thermal switch according to any one of claims 9 to 11, wherein the air discharge channels are separately controlled to open and close.

[13] The thermal switch according to claim 10 or 11, wherein the expanding members or the heat transfer fluid controllers are separately controlled for corresponding fluid storage channels.

[14] The thermal switch according to claim 9, wherein the transverse cross-section of the air discharge channel is curved and connected with the upper portion of the tunnel.

[15] A thermal switch that controls the heat transfer between a heat source and a heat sink, comprising: a main panel; a groove-shaped fluid storage channel formed on the downside of the main panel, and containing or supplied with heat transfer fluid; a groove-shaped switching channel formed on the upside of the main panel, connected with the upper portion of the fluid storage channel, and divided from the fluid storage channel by a protrusion; and an air discharge channel providing an air discharge passage connected with the switching channel, wherein heat transfer is controlled between the heat source and the heat sink by adjusting the level of the heat transfer fluid.

[16] The thermal switch according to claim 15, wherein a triangular protrusion is formed at the connecting portion of the switching channel and the air discharge channel, with a steep slope to the switching channel and a gentle slope to the air discharge channel.

[17] The thermal switch according to claim 15, wherein a burst area is formed opposite to the air discharge channel in the switching channel and a contact angle between the heat transfer fluid and the protrusion in the burst area is larger than a contact angle between the heat transfer fluid and the protrusion in other areas, except for the burst area.

[18] The thermal switch according to claim 17, wherein the protrusion forms a step at the upper portion in other areas, except for the burst area, and is connected to the upper portion of the fluid storage channel while forming a gentle curved or oblique surface in the burst area.

[19] The thermal switch according to claims 15 to 18, wherein an expanding member is disposed in the fluid storage channel to increase/decrease the level of the heat transfer fluid.

[20] The thermal switch according to claims 15 to 18, wherein a heat transfer fluid supply pipe that increases/decreases the level of the heat transfer fluid by supplying/discharging the heat transfer fluid into/out of the fluid storage channel is connected with the fluid storage channel.

[21] The thermal switch according to claims 15 to 18, wherein the fluid storage channel is made of a hydrophilic material or coated with a hydrophilic material, and the switching channel and the air discharge channel are made of a hydrophobic material or coated with a hydrophobic material.

[22] A thermal switch that controls heat transfer between a heat source and a heat sink, comprising: a main panel; a plurality of unit thermal switches arranged in the main panel; and a plurality of controllers controlling a level of heat transfer fluid in the unit switches, wherein the unit switch includes: a groove- shaped fluid storage channel formed on the downside of the main panel, and containing or supplied with the heat transfer fluid; a groove-shaped switching channel formed on the upside of the main panel, divided from the fluid storage channel by a protrusion, and connected with the fluid storage channel; and an air discharge panel connected with the switching channel and providing an air discharge passage.

[23] The thermal switch according to claim 22, wherein a triangular protrusion is formed at the connecting portion of the switching channel and the air discharge channel, with a steep slope to the switching channel and a gentle slope to the air discharge channel.

[24] The thermal switch according to claim 22, wherein a burst area is formed opposite to the air discharge channel in the switching channel and a contact angle between the heat transfer fluid and the protrusion in the burst area is larger than a contact angle between the heat transfer fluid and the protrusion in other areas, except for the burst area.

[25] The thermal switch according to claim 24, wherein the protrusion forms a step at the upper portion in other areas, except for the burst area, and is connected to the upper portion of the fluid storage channel while forming a gentle curved or oblique surface in the burst area .

[26] The thermal switch according to any one of claims 1 to 5, 9 to 11, 15 to 18, and

22 to 25, wherein a cylindrical hydrophilic assistant member having a plurality of protrusions with small grooves longitudinally formed on the outside is inserted in the fluid storage channel.

[27] The thermal switch according to claim 26, wherein the hydrophilic assistant member is provided with hydrophilic coating.