Heat pipe structure with an external liquid detouring path

Abstract

A heat pipe structure with an external liquid detouring path includes a main pipe having an interior space and divided into a top portion, a middle portion and a bottom portion. In the middle portion, 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 the liquid in the liquid-collecting groove to the bottom portion of the heat pipe.

Description

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] The invention relates to an improved heat pipe structure, and more particularly to a heat pipe having a bifurcated path to bypass a condensed liquid back to a lower portion of the heat pipe.

[0003] (2) Description of the Prior Art

[0004] Application of a heat pipe apparatus is to utilize physical phase change of a work fluid sealed in the heat pipe to perform heat transportation between two ends of the heat pipe, respectively located in two environments with a thermal difference. Referring to FIG. 1, a schematic cross-sectional view of a conventional heat pipe 1 in a typical operational state is shown. The heat pipe 1, usually made of a high-thermal-conductivity material such as a copper, is mainly an airtight pipe structure 10. The internal space of the airtight pipe structure 10 contains a specific amount of work fluid 11 for performing physical phase change.

[0005] In the art, the heat pipe 1 is firstly to have one end open for injecting the work fluid 11 and for vacuuming the internal space of the pipe 1. Then, the end is sealed to form an airtight state of the heat pipe 1.

[0006] In application of the heat pipe 1, it is posed vertically as shown in FIG. 1 or at an high-elevation angle in the two work areas 200, 300. The ambient temperature of the upper work area 200 is lower than that of the lower work area 300. The operational boiling point of the work fluid 11 is between the ambient temperatures of the upper and the lower work areas, 200 and 300 respectively.

[0007] In the art, the portion of the heat pipe 1 located in the lower work area 300 is called a vaporization portion 12, while the portion thereof located in the upper area 200 is called a condensation portion 13. In operations, the work fluid 11 sitting inside the vaporization portion 12 of the heat pipe 1 can absorb the heat in the lower work area 300 so to be vaporized as a steam floating into the condensation portion 13 in the upper work area 200. Through walls of the pipe 10, the steam of the work fluid 11 can be cooled down to condensate as liquid drops by the upper work area 200. By gravity forcing, the liquid drops of the work fluid 11 can drop directly back into or slip along the walls down into the vaporization portion 12. Upon such an arrangement, a rapid heat transportation pathway can be established to begin in the lower work area 300, via the reciprocally movement and phase change of the work fluid 11 inside the heat pipe 1, and end up finally in the upper work area 200.

[0008] In the aforesaid application of the heat pipe 1, the heat transfer between the lower work area 300 and the upper work area 200 is automatically in action as soon as the heat pipe 1 is anchored in between. No more external forcing or switching is required. Yet, in a particular case that the rate of heat-absorbing in the vaporization portion 12 (i.e. heat flow from the lower work area 300 to the heat pipe 1) is elevated to an over-heat situation, all the work fluid 11 in the vaporization portion 12 may be transformed into the steam state and no more work fluid 11 in the liquid state can stay at the bottom of the heat pipe 1. Such a dry bottom phenomenon in the heat pipe 1 is called a dual reverse flow state of the heat pipe structure.

[0009] While the heat pipe 1 meets a dual reverse flow state, the liquid drops of the work fluid 11 condensed at the condensation portion 13 would be vaporized before reaching the bottom of the vaporization portion 12. Though the phase change operation of the work fluid 11 inside the heat pipe 1 can still prevail, yet the lower portion of the vaporization portion 12 can loose its ability in absorbing the surrounding heat. In particular, in the case that the lower portion of the vaporization portion 12 is utilized to remove a heat from a specific heat-generating device, it is quite possible that the device will quickly fail or be even damaged.

[0010] Referring now to FIG. 2, a conventional loop-type heat piping is shown. In the piping as shown, the vaporization portion 12 and the condensation portion 13 are separated at a predetermined distance, but are bridged by a vapor pipe 14 and a liquid pipe 15. In application, the vaporization portion 12 can be directly mounted onto a heat-generating device. The steam of work fluid generated inside the vaporization portion 12 is sent automatically to the far-end condensation portion 13 via the vapor pipe 14. In the condensation portion 13, the steam is then cooled down by the surroundings to condense and form a liquid state of the work fluid thereinside. The liquid state of the work fluid is driven automatically back to the vaporization portion 12 via the liquid pipe 15.

[0011] In the application of the loop-type heat piping as shown in FIG. 2, for the vapor pipe 14 and the liquid pipe 15 are separate, the liquid can arrive the vaporization portion 12 without being heated in a mid-way.

[0012] Therefore, the dual reverse flow state of the work fluid as mentioned above can never occur in this type of heat piping. As a result, the heat-generating device can be better protected by the loop-type heat piping.

[0013] Nevertheless, though the loop-type heat piping may simply provide a solution to the single-tube heat pipe as shown in FIG. 1, yet the complicated structuring, the required construction space and the cost of the loop-type heat piping are still there to be further considered. Definitely, a complete substitution of the single-tube heat pipe by the loop-type heat piping is hardly to be possible. Therefore, an effort to improve the single-tube heat pipe for avoiding the notorious dual reverse flow phenomenon is surely welcome to the skilled in the art.

SUMMARY OF THE INVENTION

[0014] Accordingly, it is an object of the present invention to provide a heat pipe structure with an external liquid detouring path, in which a bifurcated pipe is constructed exteriorly to the main pipe structure for bypassing a condensed liquid back to a lower portion of the heat pipe, so that the dual reverse flow phenomenon for heat piping can be prevented and thus a normal operation of the heat pipe can be maintained.

[0015] The heat pipe structure in accordance with the present invention comprises a slender hollow main pipe having an interior space accommodating a work fluid. Further, the interior space can be divided into a top portion, a middle portion and a bottom portion. The top portion and the bottom portion are respectively located in a condensation portion and a vaporization portion as described in a conventional heat pipe, while the middle portion is located at the conjunction area of the condensation portion and the vaporization portion. The middle portion of the present invention has a circular liquid-collecting groove facing the top portion for collecting the work fluid in a liquid state drained down along an inner wall of the heat pipe. Further, an external bifurcated pipe is included to bridge spatially the liquid-collecting groove and the bottom portion for detouring the work fluid in the liquid-collecting groove to the bottom portion.

[0016] In one embodiment of the present invention, the liquid-collecting groove of the heat pipe can be formed by an inner wall and an outer rim of a liquid-collecting ring plugged inside the middle portion. The liquid-collecting ring further includes a through hole in communication spatially with both the top portion and the bottom portion.

[0017] In one embodiment of the present invention, the main pipe of the heat pipe can be formed by telescoping or joining an upper half pipe and a lower half pipe, in which the lower half pipe further includes a top end bent radial inward and upward to plug into the upper half pipe so as to form the liquid-collecting groove in between with the inner wall of the upper half pipe.

[0018] In one embodiment of the present invention, the main pipe of the heat pipe can be formed by telescoping or joining an upper half pipe and a lower half pipe, in which the upper half pipe further includes a bottom end bent radial inward and upward to form thereof the liquid-collecting groove.

[0019] In one embodiment of the present invention, the main pipe of the heat pipe can be formed by joining an upper half pipe, a liquid-collecting ring and a lower half pipe, in which an upper portion of the liquid-collecting ring is located inside the upper half pipe so as to form thereof the liquid-collecting groove in between with the upper half pipe.

[0020] In one embodiment of the present invention, the bottom portion of the interior space of the heat pipe can have a bottom end thereof enlarged to form a fluid room, and respectively a bottom (wall) of the main pipe corresponding to the fluid room is also extended to form a heat-collecting part to be mounted on a heat-generating device. In the embodiment, a lower end of the bifurcated pipe can be connected to a top side or a lateral side of the heat-collecting part of the bottom portion.

[0021] In one embodiment of the present invention, the inner wall of the main pipe located above the liquid-collecting groove can be laminated with a capillary layer for rapidly transporting liquid drops of the work fluid downward from the top portion of the heat pipe into the liquid-collecting groove.

[0022] All these objects are achieved by the heat pipe structure with an external liquid detouring path described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which:

[0024] FIG. 1 is a schematic cross-sectional view of a conventional single-tube heat pipe in operations;

[0025] FIG. 2 is a schematic view of a conventional loop-type heat piping;

[0026] FIG. 3 is a perspective view of a first embodiment of the heat pipe structure with an external liquid detouring path in accordance with the present invention;

[0027] FIG. 4 is a cross-sectional view of FIG. 3 along line a-a in operations;

[0028] FIG. 5 is a cross-sectional view of a second embodiment of the heat pipe in accordance with the present invention;

[0029] FIG. 6 is a cross-sectional view of a third embodiment of the heat pipe in accordance with the present invention;

[0030] FIG. 7 is a cross-sectional view of a fourth embodiment of the heat pipe in accordance with the present invention;

[0031] FIG. 8 is a perspective view of a fifth embodiment of the heat pipe in accordance with the present invention;

[0032] FIG. 9 is a cross-sectional view of FIG. 8 along line b-b;

[0033] FIG. 10 is a perspective view of a sixth embodiment of the heat pipe in accordance with the present invention;

[0034] FIG. 11 is a cross-sectional view of FIG. 8 in operations; and

[0035] FIG. 12 is an enlarged cross-sectional view of a portion of the main pipe of the heat pipe in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0036] The invention disclosed herein is directed to a heat pipe structure with an external liquid detouring path. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by one skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. In other instance, well-known components are not described in detail in order not to unnecessarily obscure the present invention.

[0037] To simplify the description of the present invention, elements serving the same purpose but having slight difference in appearance will be named and labeled uniquely.

[0038] In the present invention, the condensed liquid drained down along the inner wall of the heat pipe is the major concern. For a convention heat pipe as shown in FIG. 1 to meet a dual reverse flow phenomenon, those condensed liquid would be vaporized in the midway of the heat pipe and thus never reach the bottom end of heat pipe. As a consequence, the bottom end of the heat pipe would be dried out and loose its function in absorbing the external heat. Contrarily, it is the design logic of the present invention that the down flow of the condensed liquid is interrupted at midway of the heat pipe, led out of the main pipe to prevent from being vaporized before reaching the bottom end of the heat pipe, and finally sent back directly into the bottom end for performing another cycle of phase change operation. Upon such an idea, the bottom end of the heat pipe can be never dried up and can always be refilled with fluid in liquid state. Thus, the serving purpose of the heat pipe can be better fulfilled.

[0039] Referring now to FIG. 3 and FIG. 4, a first embodiment of the heat pipe structure in accordance with the present invention is respectively shown in a perspective view and a cross-sectional view along line a-a of FIG. 3. In the embodiment, the heat pipe 2 comprises a slender hollow main pipe 20 that has a sealed interior space 204 further accommodating a substantial amount of work fluid 11. As shown, the interior space 204 can be divided into a top portion 203, a middle portion 202 and a bottom portion 201. The top portion 203 and part of the middle portion 202 are resembled to the condensation portion 13 of FIG. 1, and the bottom portion 201 and another part of the middle portion 202 are resembled to the vaporization portion 12 of FIG. 1.

[0040] As shown, the inner wall 207 of the main pipe 20 at the middle portion 202 is structured to form a circular liquid-collecting groove 221 facing the top portion 203 for collecting the work fluid 11 in a liquid state (i.e. the condensed liquid) drained down along the inner wall 207 thereabove. Further, the heat pipe 2 of the present invention further includes an external bifurcated pipe 21. The bifurcated pipe 21 has an upper end 211 and an opposing lower end 212, in which the upper end 211 is connected with the liquid-collecting groove 221 for leading the work fluid 11 out of the main pipe 20, and in which the lower end 212 is connected with the bottom portion 201 for refilling the work fluid 11 back to the main pipe 20, more specifically to the bottom of the heat pipe 2. Upon such an arrangement, the condensed work fluid 11 can detour via the bifurcated pipe 21 to bypass the hi-temperature area in the bottom portion 201 and the middle portion 202 of the main pipe 20 so that no dual reverse flow phenomenon and the dry-up bottom can be found in the heat pipe structuring 2 of the present invention.

[0041] In the first embodiment, the liquid-collecting groove 221 of the heat pipe 2 is formed by plugging a liquid-collecting ring 22 into the main pipe 20 at the middle portion 202. As shown in FIG. 4, the circular concave space formed between the outer rim 222 of the liquid-collecting ring 22 and the an inner wall 207 at the middle portion 202 can thus be used as the liquid-collecting groove 221 of the present invention. The conical liquid-collecting ring 22 further includes a through hole 220 for bridging spatially the top portion 203 and the bottom portion 201. By providing the liquid-collecting ring 22, the steam of the work fluid 11 can freely rise from the bottom portion 201 to the top portion 203 via the through hol3 220, and the liquid work fluid 11 drained down along the inner wall 207 above the middle portion 202 can be successfully collected in the liquid-collecting groove 221.

[0042] In the present invention, the connection between the bifurcated pipe 21 and the main pipe 20 can be made by firstly drilling the main pipe 20 at proper locations and then welding or threading the ends 211, 212 of the bifurcated pipe 21 to the respective drilled holes on the main pipe 20. Or, third connecting parts can also be introduced to engage the ends 211, 212 of the bifurcated pipe 21 with the main pipe 20. However, possible connection means for engaging the bifurcated pipe 21 and the main pipe 20 are well known to the skilled person in the art, so related details regarding such connections will be omitted herein.

[0043] In the present invention, the bifurcated pipe 21 can be made of copper, appropriate metal, or plastics. While a plastic pipe is used as the bifurcated pipe 21, two connecting parts are required to engage the plastic bifurcated pipe 21 to the metal main pipe 20.

[0044] Referring now to FIG. 5, a second embodiment of the heat pipe structure in accordance with the present invention is shown in a cross sectional view. Compared to the first embodiment of FIG. 4, the main pipe 20 of this embodiment is formed by telescoping or joining an upper half pipe 20a and a lower half pipe 20b. The upper half pipe 20a has its top end sealed, while the lower half pipe 20b has its bottom end sealed. As shown, the lower half pipe 20b further includes a top end bent radial inward and upward to form a taper head for plugging into the upper half pipe 20a. By providing the taper head of the lower half pipe 20b, the liquid-collecting groove 22 can be formed between the inner wall 207 of the upper half pipe 20a and the taper head (i.e. the liquid-collecting ring 22 in this embodiment).

[0045] In the second embodiment, the introduction of the bifurcated pipe 22 is the same as that in the first embodiment.

[0046] Referring now to FIG. 6, a third embodiment of the heat pipe structure in accordance with the present invention is shown in a cross sectional view. Compared to the first embodiment of FIG. 4 and the second embodiment of FIG. 5, the main pipe 20 of the heat pipe 2 in this third embodiment is formed by joining an upper half pipe 20a, a liquid-collecting ring 22 having a central through hole 220, and a lower half pipe 20b. An upper portion 222 of the liquid-collecting ring 22 is located inside the upper half pipe 20a such that the liquid-collecting groove 221 can be formed by the limited circular space between the upper portion 222 and the upper half pipe 20a. Also, the inclusion of the bifurcated pipe 22 in this third embodiment is the same as that in the first embodiment or in the second embodiment.

[0047] In the third embodiment of the present invention, the connection between the liquid-collecting ring 22 and the upper half pipe 20a or that between the liquid-collecting ring 22 and the lower half pipe 20b can be a welding connection, a pure press-tight connection, or a threading connection. In the case that a threading connection is adopted, an external thread can be made to the liquid-collecting ring 22 and a corresponding internal thread can be made to the upper half pipe 20a or the lower half pipe 20b. Also, while in engaging threads of the liquid-collecting ring 22 and the upper half pipe 20a or the lower half pipe 20b, appropriate seal parts such as O-rings or air-tight belts can be applied in between. Yet, such a piping connection technique is well known to the skilled person in the art, and details will be omitted herein.

[0048] Referring now to FIG. 7, a fourth embodiment of the heat pipe structure in accordance with the present invention is shown in a cross sectional view. Compared to the first embodiment of FIG. 4 and the second embodiment of FIG. 5, the main pipe 20 of this embodiment is also formed by telescoping or joining an upper half pipe 20a and a lower half pipe 20b. The upper half pipe 20a has its top end sealed, while the lower half pipe 20b has its bottom end sealed. As shown, a bottom end 22 of the upper half pipe 20a is bent radial inward and upward so as to directly form thereof the liquid-collecting groove 22. Also, the construction of the bifurcated pipe 22 in this fourth embodiment is the same as that in any of previous embodiments.

[0049] Referring now to FIG. 8 and FIG. 9, a fifth embodiment of the heat pipe structure in accordance with the present invention is shown in a perspective view and a cross sectional view of FIG. 8 along line b-b, respectively. In this embodiment, the inner wall 207 at the bottom portion 201 of the interior space 204 of the heat pipe 2 is enlarged to form a heat-collecting part 23 having a fluid room 233. The heat-collecting part 23 is used to mount on a heat-generating device (not shown in the figure). As shown in the embodiment, the lower end 212 of the bifurcated pipe 21 is connected to a top side 230 of the heat-collecting part 23. That is to say that the liquid work fluid 11 collected in the liquid-collecting groove 221 is led directly to the fluid room 233 of the bottom portion 201 via the bifurcated pipe 21.

[0050] In the fifth embodiment of the present invention, the construction of the main pipe 20 is similar to that of the second embodiment as shown in FIG. 5. Yet, a major difference in between is that the upper half pipe 20a of the fifth embodiment is extended to sleeve tightly over the lower half pipe 20b till the lower end of the upper half pipe 20a hits the top side 230 of the heat-collecting part 23.

[0051] Referring now to FIG. 10, a sixth embodiment of the heat pipe structure in accordance with the present invention is shown in a perspective view. Compared to the fifth embodiment of FIG. 8, the sixth embodiment has the lower end 212 of the bifurcated pipe 21 connected to a lateral side 231 of the heat-collecting part 23 of the main pipe 20.

[0052] Referring now to FIG. 11, a cross-sectional view of FIG. 8 in operations is shown. As shown, the heat-collecting part 23 of the heat pipe 2 is directly mounted on a heat-generating device 4. The heat generated in the heat-generating device 4 is led into the fluid room 233 to boil the work fluid 11 thereinside. The steam of the work fluid 11 then floats upward freely in the interior space 204 of the main pipe 20 from the fluid room 233 of the bottom portion 201 to the top portion 203. In the top portion 203, the steam exchanges heat with the inner wall 207 thereof so as to condense to form liquid drops of the work fluid 11. Part of the liquid drops fall directly down through the interior space 204 to the fluid room 233, while part of the liquid drops formed on the inner wall 207 at the top portion 203 of the main pipe 20 would drain down along the inner wall 207 to be collected by the liquid-collecting groove 221 at the middle portion 202. The work fluid 11 collected by the liquid-collecting groove 221 is then detoured out of the main pipe 20 by the bifurcated pipe 21 and thereafter refilled into the fluid room 233 of the heat-collecting part 23. In the fluid room 233, the work fluid 11 is again to begin another cycle of phase change operation as described above.

[0053] As shown, to speed up the heat dissipation from the main pipe 20 to the surroundings, an appropriate fin structure 3 is constructed at the condensation portion of the heat pipe 2 (including the top portion 203 and an upper part of the middle portion 202). Preferably, a fan (not shown in the figure) can be used to enhance the dissipation efficiency of the fin structure 3.

[0054] In the present invention, the heat-collecting part 23 can be shaped as a hollow disk body, a hollow square body, a hollow thin plate body, or any type of hollow body that can fit a particular shape of the heat-generating device 4.

[0055] Referring now to FIG. 12, an enlarged cross-sectional view of a portion of the main pipe of the heat pipe in accordance with the present invention is shown. As shown, the inner wall 207 of the main pipe 20 located above the liquid-collecting groove 221 is laminated with a capillary layer 208 for rapidly transporting liquid drops of the work fluid at the inner wall 207 of the heat pipe downward into the liquid-collecting groove 221. Such a capillary layer and its construction are well known to the skilled person in the art, and so details will be omitted herein.

[0056] In the present invention, by providing an external liquid detouring path (i.e. the bifurcated pipe) to the single-tube heat pipe structure, the condensed work fluid can then bypass the vaporization portion of the heat pipe and can be sent directly to the lower portion of the heat pipe. Upon such an arrangement, the dual reverse flow phenomenon for heat piping can be avoided in the heat pipe of the present invention and a normal operation of the heat pipe can be ensured.

[0057] While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be without departing from the spirit and scope of the present invention.

Claims

I claim:

1. A heat pipe structure, comprising a main pipe having an interior space accommodating a work fluid, the interior space being divided into thereof a top portion, a middle portion and a bottom portion, characterized in that: the middle portion has a circular liquid-collecting groove facing the top portion for collecting the work fluid in a liquid state drained down along an inner wall of the heat pipe, and a bifurcated pipe is included to bridge the liquid-collecting groove and the bottom portion for detouring the work fluid in the liquid-collecting groove to the bottom portion.

2. The heat pipe structure according to claim 1, wherein said liquid-collecting groove is formed by said inner wall and an outer rim of a liquid-collecting ring plugged inside said middle portion, and the liquid-collecting ring further includes a through hole in communication spatially with both said top portion and said bottom portion.

3. The heat pipe structure according to claim 1, wherein said main pipe is formed by joining an upper half pipe and a lower half pipe, in which the lower half pipe further includes a top end bent radial inward and upward to plug into the upper half pipe so as to form said liquid-collecting groove with said inner wall at the upper half pipe.

4. The heat pipe structure according to claim 1, wherein said main pipe is formed by joining an upper half pipe and a lower half pipe, in which the upper half pipe further includes a bottom end bent radial inward and upward to form thereof said liquid-collecting groove.

5. The heat pipe structure according to claim 1, wherein said main pipe is formed by joining an upper half pipe, a liquid-collecting ring and a lower half pipe, in which an upper portion of the liquid-collecting ring is located inside the upper half pipe so as to form said liquid-collecting groove in between with the upper half pipe.

6. The heat pipe structure according to claim 1, wherein said bottom portion has a bottom end thereof enlarged to form a fluid room while a bottom of said main pipe corresponding to the fluid room is also extended to form a heat-collecting part to be mounted on a heat-generating device, wherein a lower end of said bifurcated pipe is connected to a top side of the heat-collecting part.

7. The heat pipe structure according to claim 1, wherein said bottom portion has a bottom end thereof enlarged to form a fluid room while a bottom of said main pipe corresponding to the fluid room is also extended to form a heat-collecting part to be mounted on a heat-generating device, wherein a lower end of said bifurcated pipe is connected to a lateral side of the heat-collecting part.

8. The heat pipe structure according to claim 1, wherein said inner wall of said main pipe located above said liquid-collecting groove is laminated with a capillary layer.

9. A heat pipe structure, comprising: an upper half pipe, formed as a pipe having an upper end sealed; a lower half pipe, formed as a pipe having a lower end sealed; a liquid-collecting ring, formed as a conical ring having a central through hole, located between the upper half pipe and the lower half pipe, further having an upper portion thereof located inside the upper half pipe so as to have a cavity between the upper portion and the upper half pipe formed as a liquid-collecting groove; and a bifurcated pipe, further having an upper end and an opposing lower end, the upper end connecting with the liquid-collecting groove, the lower end connecting with a bottom of the lower half pipe close to the lower end.

10. The heat pipe structure according to claim 9, wherein said liquid-collecting ring and the lower half pipe is made as a unique piece.

11. The heat pipe structure according to claim 9, wherein said liquid-collecting ring and the upper half pipe is made as a unique piece.

12. The heat pipe structure according to claim 9, wherein said bottom of said lower half pipe is enlarged to form a heat-collecting part to be mounted on a heat-generating device.

13. The heat pipe structure according to claim 9, wherein said upper half pipe is laminated thereinside with a capillary layer.