TWI243885B - Heat pipe structure with an external liquid detouring path - Google Patents

Abstract

A heat pipe structure with an external liquid detouring path includes a main pipe having an interior space divided into a top portion, a middle portion and a bottom portion. In the middle portion of the heat pipe, a circular liquid-collecting groove facing the top portion is constructed for collecting a liquid drained down along the inner wall of the pipe. The heat pipe also includes a bifurcated pipe to detour liquid in the liquid-collecting groove to bottom portion of the heat pipe.

Description

1243885 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to an improved single-pipe heat pipe structure, especially a half-loop heat pipe structure that integrates a branched liquid return pipe. [Previous technology] According to the knowledge, the application of the heat pipe is mainly to use the two-phase change of evaporation and condensation of the working fluid contained in the heat pipe to carry out the heat transfer operation between the environment where the two ends of the heat pipe are located; see the first figure, It is a schematic sectional view of the operation of a conventional heat pipe 1. The heat pipe 1 is a closed pipe structure 10 made of a material with high thermal conductivity (such as copper). In a closed space communicating with the pipe, a heat pipe 1 is provided. Quantitative working fluid 1 1. The production of the heat pipe 1 usually involves firstly closing one end of the pipe structure 10 and opening one end, and then extracting air at the open end to form a certain degree of vacuum in the tube. Then, the working fluid is injected from the open end, and the open end is closed. . In the operation of heat pipe 1, it is set upright or in a high elevation angle in the two working areas 2 0, 3 0, and the ambient temperature of the working area 2 0 above the higher position is lower than the lower position. The ambient temperature of the lower working area 3 0 0, and the operating boiling point of the working fluid 11 in the heat pipe 1 must be lower than the ambient temperature of the lower working area 3 0 0. In general, the part of the heat pipe 1 in the lower working area 300 is called the evaporation part 12 and the part of the heat pipe 1 in the upper working area 2 00 is called the condensation part 1 3; during operation, the heat pipe 1 evaporating part 1 The working fluid 11 in 2 absorbs and boils at 300 in the lower working area, and rises as a vapor in the confined space 10 to the condensing portion 13 in the upper working area 200. At this point, through the tube junction

1243885 V. Description of the invention (2) The working fluid in the gas state of the tube wall of structure 10 can release heat to the upper working area 2 0 0 and condense to the liquid working fluid 1 1 on the tube wall. Drop along the inner wall of the pipe body 10 back to the evaporation section 12; in this way, by repeatedly evaporating and condensing the working fluid 11 between the heat pipe 1 evaporation section 12 and the condensation section 13, the lower working area 3 can be effectively removed The heat in 0 0 is transferred to the upper working area 2 0 and released. In the application of the conventional heat pipe structure, after the heat pipe 1 is set in the two working areas 2 0, 3 0, the heat exchange operation between the 2 working areas 2 0, 3 0 will be automatically performed, and there is no need to Perform any switching control for startup or shutdown. However, the amount of heat generated in the current working area 3 0 0 is too large, so that the working fluid 11 in the heat pipe 1 evaporates in the evaporation part 12 or rises to the condensation part 13 at a speed greater than the working fluid 1 1 in the condensation part 13 When condensing or sliding down to the speed of the evaporation section 12 (that is, when reaching a critical point), a so-called "double countercurrent phenomenon" will occur. Under the situation of the double countercurrent phenomenon of the heat pipe 1, the gas-liquid phase change in the space of the pipe structure 10 will cause instability or disparity. At this time, the condensing working fluid 11 will not return to the pipe structure 1 Before the bottom of 0, the line will evaporate. In this way, the drying phenomenon in the bottom of heat pipe 1 will be caused. The bottom of heat pipe 1 is usually a heating interface that is in direct contact with the heating element, so the drying phenomenon will quickly cause heat. High temperature components fail or even break. Please refer to the second figure, which is a schematic diagram of a conventional loop-type heat pipe. In this loop-type heat pipe, the evaporation part 12 and the condensation part 13 are arranged at a distance, and a steam pipe 1 4 is used. The heat pipe structure is formed into a loop structure with another liquid pipe 15. In the application of loop heat pipe, the evaporation section 12 is straight

1243885 V. Description of the invention (3) It is connected to the heating element, and its evaporation gas system is transported to the condensing section 13 by the vapor line 14, and the liquid working fluid condensed in the condensing section 13 is from the liquid line. 15 is returned to the evaporation section 12. In the loop type heat pipe, since the pipeline for transporting steam and liquid is divided into 1, in the return flow of the condensing working fluid, not only will there not be a relay heat absorption phenomenon, and it will directly transport the liquid working fluid back to the evaporation section 12 operation. In addition to avoiding the aforementioned drying phenomenon, the heat pipe can ensure the heat dissipation effect of the heating element and directly protect the operation of the heating element. Of course, the loop type heat pipe can solve some problems of the single tube type heat pipe, but because of its more complicated structure, more parts required for installation (such as fixing parts, etc.), and large installation space requirements, the loop type heat pipe is completely replaced It is obviously impossible to set up a single-tube heat pipe with simple and low cost. That is, improving the traditional single-tube heat pipe structure to avoid possible drying of its operation is obviously a topic worthy of development in the application of heat pipes. [Summary of the invention] The main purpose of the present invention is to provide a semi-loop type heat pipe junction structure, which is based on an external liquid return pipeline structure on a single-pipe heat pipe structure, so as to avoid drying of the heat pipe evaporation part. Phenomenon to ensure the operational efficiency of the use of heat pipes. The semi-loop heat pipe structure of the present invention comprises an elongated hollow main pipe body containing a working fluid. The inner space of the hollow main pipe wall can be divided into a bottom section, a middle section and a top section, wherein the bottom section and the Part of the middle section belongs to the evaporation section of the heat pipe, while the other part of the top section and the middle section belongs to

1243885 V. Description of the invention (4) Condensing part of the heat pipe The hollow main body of the heat pipe structure of the present invention has a concave wall facing the top section of the pipe wall in the middle section, and a liquid collecting tank for collecting working fluid flowing down the pipe wall. Including a peripheral return pipe, this upper nozzle and lower nozzle, among which the upper nozzle is connected to the hollow main pipe which collects the working fluid collected by the liquid collecting tank, and the exported working fluid is recovered to the hollow main pipe. A flow tube is also provided on the bottom, and a collecting tank body with the following nozzles is used, and the section is in the middle. In one embodiment of the present invention, a plug wall may be used to form the center. The set of through holes in the pipe system of the present invention may be collected from a series of inwardly-shrinkable pipes. When the system is in a one-way pipe, the upper casing in the pipe system of the present invention can be a part of the upper casing, the header, and the outer edge of the hollow main liquid ring, which is used to communicate the upper casing and a state of an embodiment. The structure ^ to the end is in the set of liquid tank. The upper casing of one embodiment and the lower end of a rolled-in configuration are formed. The upper casing of an embodiment, a liquid ring and the lower casing are formed in the outer edge of the liquid collecting tank in the semi-circular heat pipe structure. The liquid collecting tank is formed between the liquid collecting ring and the tube and the tube wall of the hollow main body, and further includes a bottom section and a top section of the hollow main body. The middle and half-loop heat pipe structure is composed of hollow main lower casings. The upper end of the lower casing is inserted into the lower end of the upper casing when the casing is assembled. When completed, it is in shape with the inner wall of the upper casing. The semi-circular heat pipe structure is composed of a hollow main lower casing, and the lower end of the upper casing is formed. When the upper casing and the lower casing are assembled, the liquid collecting tank of the present invention is completed. The middle and half-loop heat pipe structure is composed of a hollow main liquid collection ring and a lower casing. When the tube assembly is completed, the liquid collection ring is located on the upper casing and the inner wall of the upper casing to form the collection of the present invention.

Page 9 1243885 V. Description of the invention (5) Liquid tank. In one embodiment of the present invention, the bottom wall of the semi-circular heat pipe structure can be enlarged to form a heat collector for convenient installation on a heating element, and the nozzle under the return pipe can be connected to This collector is on the top or side. In one embodiment of the present invention, the main body of the semi-circular heat pipe structure is located in the pipe wall above the liquid collecting tank, and a capillary structure layer can be laid in order to facilitate the transfer of the condensed liquid working fluid into the liquid collecting tank. In order to allow your reviewers to further understand and agree with the present invention, a detailed description is given below in conjunction with the drawings. [The implementation party is in nature, so in the other, the liquid under this hair first collects the main endothermic fluid as the fluid to heat it, so that its force can refer to the formula] In the following description, in order to obtain the difference of the present invention In the embodiment, if there is a component, the main method is to use the same name and drawing number. The single-tube hot working fluid is placed farther from the bottom of the heat pipe and a bypass pipe is used for bypassing. Use of heat absorption; as a result, it can slide down to the bottom of the heat pipe and evaporate because it is up, causing the bottom of the heat pipe to dry quickly, making it impossible to preview the heat pipe as shown in the third and fourth figures. The function is the same, but the shape of the slightly condensed end of the tube is mainly transported back to avoid cold rise. The lack of heat dissipation is based on the replenishment performance of the liquid liquid vapor and wall liquid at the bottom of the heat pipe at the heat absorption zone along the tube wall. Inventing the half circuit

Page 10 1243885 V. Description of the invention (6) Three-dimensional and cross-sectional schematic diagrams along the line a-a of the first embodiment of the heat pipe structure; as shown in the figure, the semi-loop heat pipe structure 2 of the present invention has a main system inside An elongated hollow main body 20 containing a working fluid 11 and the wall 20 of this main body 2 0 7 internal space 2 0 4 can be further divided into a bottom section 2 01, a middle section 202 and a top section. 2 0 3, where the bottom section 2 01 and the middle section 2 0 2 are close to the bottom section 2 0 1 belong to the evaporation section of the conventional heat pipe (see the evaporation section 1 2 of the first figure), and the top section 2 0 The third part and the middle part 2 0 2 close to the top part 2 0 3 belong to the condensation part of the conventional heat pipe (see the condensation part 1 3 in the first figure). As shown in the figure, the hollow main body 20 of the heat pipe structure 2 of the present invention is provided with a concave surface facing the top section 2 0 on the tube wall 2 7 of the middle section 2 0 3 to collect the flow down the tube wall 2 7 A collecting tank 2 2 1 of the working fluid 1 1, and the heat pipe structure 2 may further include a peripheral return pipe 2 1, and the return pipe further includes an upper nozzle 2 1 1 and a lower nozzle 212, among which The nozzle 211 is connected to the liquid collecting tank 221, and is used to lead the working fluid 1 1 collected in the liquid collecting tank 2 2 1 to the hollow main body 2 0, and the lower nozzle 2 1 2 will be from the upper nozzle 2 1 1 The derived working fluid 1 1 is recovered to the bottom section 2 0 1 of the hollow main body 20, and thereby, the reflux of the liquid working fluid 1 1 avoids the high-temperature main body 2 of the bottom section 2 1 and the middle section 2 0 2. Part 0, and feed directly to the bottom end of the main body 20, which is the main endothermic operation, to avoid the possible "drying phenomenon" of heat pipe operation. In the first embodiment, the liquid collecting tank 2 2 1 of the semi-circular heat pipe structure 2 is a liquid collecting ring 22 and a tube wall 2 of the hollow main body 20 by a plug placed in the middle section 20 of the hollow main body 20. 0 7 structure, the annular concave space formed between the outer edge 2 2 2 of the liquid collecting ring 2 2 and the tube wall 2 0 7 is defined as the liquid collecting tank 2 2 1 of the present invention; as shown in the figure, this cone Shaped collecting ring 22 also includes a central through hole

Page 11 1243885 V. Description of the invention (7) 2 2 0 is used to connect the hollow main body 2 0 internal space 2 0 4 with the bottom section 2 0 1 and the top section 2 0 3 so that the gaseous working fluid 1 1 is obtained from The hollow main body rises freely within 20 minutes. In the present invention, the communication between the return pipe 21 and the main body 20 is formed, and the two ends of the return pipe 21 can be welded or screwed after the main body 20 is drilled, or through another connection member. The return operation of the return pipe 21 on the main body 20 is performed. However, the bypass process of this type of pipe is well known to those skilled in this art, so it will not be illustrated in detail here. In the present invention, the bypass tube 21 of the bypass can be a copper tube, a metal tube, or a suitably configured plastic tube (must be connected to a metal main body 20 with a conventional two-way tube connector). Please refer to the fifth figure, which is a schematic cross-sectional view of the second embodiment of the half-loop heat pipe structure 2 of the present invention; compared with the first embodiment shown in the fourth figure, in this second embodiment, the half-loop type The hollow main body 2 0 of the heat pipe structure 2 is composed of an upper end closed upper sleeve 20 a and a lower end closed lower sleeve 20 b. The upper end of the lower sleeve 2 0 b is internally contracted. The shape structure (that is, the above-mentioned collecting ring 22 and the lower sleeve 20 b are made into a single formed part) is inserted into the lower end of the upper sleeve 20a while the upper end of the lower sleeve 20b is assembled When the assembly is completed, the liquid collecting tank 2 2 1 of the present invention is formed between the inner wall 207 of the upper sleeve 20 a and the configuration of the return pipe 21 is the same as the first embodiment described above. Please refer to the sixth figure, which is a schematic cross-sectional view of the third embodiment of the semi-loop heat pipe structure 2 of the present invention; compared with the first embodiment shown in the fourth figure and the second embodiment shown in the fifth figure, In this third embodiment, half time

Page 12 1243885 V. Description of the invention (8) The hollow main body 2 of the road-type heat pipe structure 2 is composed of an upper sleeve 2 a, a collecting ring 2 with a central through hole 2 2 0, and a lower sleeve. The tube 20b is assembled in sections. When the upper casing 20a, the collection ring 22 and the lower casing 20b are assembled, the collection ring 22 is located in the upper casing 20a. Part (top part shown in the figure), that is, the outer edge 2 2 2 and the inner wall 2 0 7 of the upper sleeve 20 a form the liquid collecting tank 2 2 1 of the present invention; as for the configuration of the return pipe 21, the The foregoing embodiments are the same. In the third embodiment, the connection system between the liquid collecting ring 22 and the upper sleeve 20 a and the lower sleeve 20 b may be welding, tightly fitting, or screwing. If screwing is used, At this time, the outer ring surface of the liquid collecting 'ring 22 can be made into an externally threaded surface, and the inner wall of the corresponding tube of the upper casing 20a and the lower casing 20b is made of a matching internal thread. Of course, during assembly Appropriate seals (such as 0-rings, waterstops, etc.) are still necessary, but the use of this type of connection is well known to those skilled in this art, so it will not be repeated here. Please refer to the seventh figure, which is a schematic cross-sectional view of the fourth embodiment of the half-loop heat pipe structure 2 of the present invention; compared with the first embodiment shown in the fourth figure and the second embodiment shown in the fifth figure, In this fourth embodiment, although the hollow main body 20 of the half-loop heat pipe structure 2 is also composed of an upper casing 20a and a lower casing 20b, the lower end of the upper casing 20a It is formed in the form of a one-way pipe (that is, the aforementioned collecting ring 22 and the upper sleeve 20 a are made into an integrally formed piece), thereby directly forming the collecting tank 2 2 1 of the present invention; as for The configuration of the return pipe 21 is the same as that of the foregoing embodiments. Please refer to the eighth and ninth figures, which are three-dimensional and cross-sectional schematic diagrams along the line bb of the fifth embodiment of the half-loop heat pipe structure of the present invention, as shown. In this embodiment, the half-loop type Bottom section of heat pipe structure 2 0 1

Page 13 1243885 V. Description of the invention (9) The tube wall 2 0 7 can be enlarged to form a heat collector 2 3 with a larger liquid chamber 2 3 3, which is used to facilitate the installation on a heating element (not shown) The upper and lower nozzles 2 1 2 of the return pipe 21 are communicated from the top surface 2 3 0 of the heat collector 23 to the inner space 204 (also the liquid chamber 233) of the main body 20. As shown in the figure, in the fifth embodiment, although the main body 20 is the same as the second embodiment described in the fifth figure, "the two tubes 20a, 20b are nested, and the liquid collecting tank 221 is formed by the lower sleeve 20 The top end of b and the inner edge surface 2 7 of the upper sleeve 2 a form a pattern of “”, but the bottom end of the upper sleeve 20 a is extended to fit to the top surface of the heat collector 2 3 2 3 0 ° Please Refer to FIG. 10, which is a schematic cross-sectional view of a sixth embodiment of the semi-loop heat pipe structure of the present invention. Compared with the fifth embodiment shown in FIG. 8, in the sixth embodiment, the return pipe 21 The lower nozzle 2 2 is connected from the side surface 231 of the heat collector 23 to the heat collector 23 of the main body 20. Please refer to the eleventh diagram, which is a schematic cross-sectional view of the embodiment used in the eighth diagram; as shown, the heat collector 2 3 of the half-loop heat pipe structure 2 is arranged on a heating element 4 to directly The contacting method directs the heat-generating conductance of the heating element 4 to the main body 20 and the working fluid 1 1 in the boiling liquid chamber 2 3 3, and the vaporized working fluid flows along the inner space 2 0 of the main body 2 0 4 Naturally rise to the condensing part of the heat pipe structure 2 (ie, the top section 2 0 3 and the middle section 2 2 2), and then heat exchange with the tube wall 2 7 7 to condense into a liquid working fluid 1 1. This liquid working fluid 1 1 and flow down the pipe wall 2 0 7 to the middle section 20 of the main body 2 0 2 and are collected by the heat collecting tank 2 2 1. The working fluid in the heat collecting tank 2 2 1 is returned by the external flow. The tube 21 is fed back into the heat collector 23 and subjected to a second endothermic evaporation.

Page 14 1243885 V. Description of the invention (ίο) As shown in the figure, it is to accelerate the heat dissipation of the condensation part of the heat pipe structure 2 (ie, the top section 230 and the middle section 2 02), which is the condensation of the heat pipe structure 2. An appropriate configuration of the heat dissipation fins 3 (which can be matched with a heat dissipation fan) is arranged on the part to accelerate the heat diffusion and discharge in the main body 20. In the present invention, the configuration of the heat collector 23 may be a circular dish body, a rectangular body, a hollow thin plate body, or other configurations that cooperate with the heating element as shown in the figure. Please refer to the twelfth figure, which is an enlarged schematic cross-sectional view of an embodiment of a main pipe wall part of a semi-circular heat pipe structure of the present invention. Above the main pipe 20 collecting tank 2 2 1 (that is, the aforementioned The relative position of the upper casing 2a] is laid on the tube wall 2 0 7 with a capillary structure layer 2 0 8 to facilitate the transfer of the liquid working fluid in the internal space 2 4 of the heat pipe condensation section to the liquid collecting tank 2 2 1 The design of this capillary structure layer 208 is also commonly used in conventional techniques. The difference is that in the conventional heat pipe technology, the laying of the capillary structure layer 208 is used to smoothly condense the liquid working fluid. Diversion along the tube wall to the bottom end of the heat pipe (instead of the liquid collecting tank 2 2 1 of the present invention), so the conventional heat pipe 1 shown in the first figure is taken as an example. When the heat pipe 1 < When a capillary structure layer (not shown) is added in 0, the laying is mainly based on the whole pipe structure. In the present invention, the semi-loop heat pipe structure is provided by an external return pipe. On the single-tube heat pipe structure, a liquid circuit is constructed to reduce the influence of the heat absorption of the main body. It can effectively avoid the drying phenomenon of the heat pipe evaporation part, and can ensure the operation efficiency of the use of the heat pipe. The above description uses a preferred embodiment to describe the present invention in detail, but not to limit the scope of the present invention. Can understand

Page 15 1243885 V. Description of the invention (11) Making minor changes and adjustments will still not lose the essence of the invention, nor depart from the spirit and scope of the invention. To sum up, the specificity of the implementation of the present invention has already met the requirements of the invention patent stipulated in the Patent Law. I invite your reviewing committee to review and grant the patent as a prayer.

Page 16 1243885 Schematic description of the first picture, the second picture, the third picture is the system is the intention system is the intention system is the intention system is the intention system is the intention system system diagram Four diagrams, fifth diagrams, sixth diagrams, seventh diagrams, eighth diagrams, ninth diagrams, tenth diagrams, eleventh, twelfth, conventional heat pipe operation, a schematic diagram of a conventional loop heat pipe, and a semi-loop heat pipe of the present invention. The three-dimensional view of the first embodiment of the structure j The schematic diagram of the cross-section taken along the line a-a in the operation of the embodiment in the third figure; the cross-section of the second embodiment of the semi-loop heat pipe structure of the present invention A cross-sectional view of an example, a cross-sectional view of a fourth embodiment of the semi-loop heat pipe structure of the present invention, a three-dimensional view of a fifth embodiment of the semi-loop heat pipe structure of the present invention, and a schematic cross-sectional view of the embodiment along the line bb in the eighth figure A three-dimensional illustration of the sixth embodiment of the half-loop heat pipe structure, j is a schematic cross-sectional view of the first embodiment of the eighth figure; and a part of the main pipe of the half-loop heat pipe structure of the present invention An enlarged cross-sectional view of the embodiment of FIG. Drawing number description: Half-loop heat pipe Heating element 1 Traditional heat pipe 3 Radiating fin

Page 12 1243885 Schematic illustration

Page 18 10 Tube structure 11 Working fluid 12 Evaporation section 13 Condensing section 14 Vapor line 15 Liquid line 20 Main body 21 Return pipe 22 Collector ring 23 Heat collector 200 Upper working area 201 Bottom section 202 Middle section 203 Top section 204 Internal space 207 Tube wall 208 Capillary structure layer 211 Upper nozzle 212 Lower nozzle 220 Through hole 221 Set: liquid tank 222 outer edge 230 top surface 231 side 233 liquid 'body chamber 300 working area

Claims (1)

1243885 VI. Scope of patent application 1. A semi-circular heat pipe structure comprising a hollow main pipe containing a working fluid, and the space in the wall of the hollow main pipe is divided into a bottom section, a middle section and a top section. It is characterized in that the hollow main body is located on the tube wall of the middle section and is provided with a concave surface facing the top section to collect the working fluid flowing down the tube wall, and the heat pipe structure further includes an outer A return pipe is provided. The upper nozzle of the return pipe is connected to the liquid collecting tank, and the lower pipe opening is connected to the bottom section for guiding the working fluid in the liquid collecting tank to the bottom section. . 2. The semi-circular heat pipe structure according to item 1 of the scope of the patent application, wherein the liquid collecting tank is composed of a liquid collecting ring plugged in the hollow main body and the tube wall, and the liquid collecting The outer edge of the ring and the pipe wall form the liquid collecting tank, and further include a through hole for connecting the bottom section and the top section. 3. The semi-loop heat pipe structure described in item 1 of the scope of patent application, wherein the hollow main pipe system described in the above is composed of an upper casing and a lower casing. The upper end of the lower casing is within The reduced form is configured to be inserted into the lower end of the upper sleeve when the sleeve is assembled, and the upper end of the lower sleeve is to form the liquid collecting tank with the inner wall of the upper sleeve when the sleeve is completed. 4. The semi-circular heat pipe structure according to item 1 of the scope of patent application, wherein the hollow main pipe system is composed of an upper casing and a lower casing, and the lower end of the upper casing is connected to the inside of the tube. Involved in form composition, when this 1243885 VI. Scope of patent application When the sleeve and the lower sleeve are assembled, the lower end of the upper sleeve forms the liquid collecting tank. 5. The semi-circular heat pipe structure according to item 1 of the scope of patent application, wherein the hollow main pipe system is composed of an upper casing, a liquid collecting ring, and a lower casing. When the assembling of the tube, the liquid collecting ring and the lower casing is completed, the Zheng Fen of the liquid collecting ring located in the upper casing forms the liquid collecting tank with the dead wall of the upper casing. 6. The semi-circular heat pipe structure according to item 1 of the scope of the patent application, wherein the tube wall of the bottom section is enlarged < formed as a heat collector for setting on a heating element, and The lower nozzle of the return pipe is connected to a top surface of the heat collector. 7. The semi-circular heat pipe structure according to item 1 of the scope of patent application, wherein the tube wall of the bottom section is enlarged to form a heat collector for setting on a heating element, and the The lower nozzle of the return pipe is connected to one side of the heat collector. 8. The semi-circular heat pipe structure according to item 1 of the scope of the patent application, wherein the main body is further provided with a capillary structure layer in the pipe wall above the liquid collecting tank. Page 20 1243885 VI. Scope of patent application 9. A semi-circular heat pipe structure, including: an upper sleeve, which is a closed body at the upper end; a lower sleeve, which is a closed body at the lower end; The liquid ring is a conical ring body with a central through-hole, which is arranged between the upper casing and the lower casing. The main system of the liquid collecting ring is sleeved in the upper casing and above it. The edge and the inner wall of the upper sleeve form a liquid collecting tank with a concave surface facing upward; and a return pipe having an upper nozzle and a lower nozzle which are connected to the liquid collecting tank and the lower nozzle It is connected to the bottom of one of the lower sleeves. 10. The semi-loop heat pipe structure according to item 9 of the scope of the patent application, wherein the liquid collecting ring and the lower casing are integrally formed. 11. The semi-circular heat pipe structure according to item 9 of the scope of patent application, wherein the liquid collecting ring and the upper sleeve are integrally formed. 1 2. The semi-circular heat pipe structure according to item 9 of the scope of the patent application, wherein the bottom of the lower casing is enlarged to form a heat collector for use on a heating element. _ 13. The semi-loop heat pipe structure according to item 9 of the scope of patent application, wherein a capillary structure layer is laid in the upper casing. Page 21