Heat pipe and method for manufacturing the same   

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat pipe, and in particular to a heat pie that can be used to dissipate the heat of a heat-generating source of an electronic device and a method for manufacturing the same.

2. Description of Prior Art

With the continuous advancement of the operating speed of the central processing unit (CPU) of a computer, the amount of heat generated by the operation of the computer is increasing to a large extent. The heat-dissipating device comprised of an aluminum-extruded heat sink and a fan has become unable to satisfy the requirements for the heat dissipation of the current central processing unit. Thus, the manufacturers in this field propose novel heat pipes having better heat-dissipating efficiency. Then, this kind of novel heat pipe is combined with a heat sink to solve the problem of heat dissipation at the current stage. However, the design of the internal structure of the heat pipe is dependent on the flowing speed of the gas and fluid within the heat pipe and the usage of space. Therefore, the present Inventor aims to propose a novel heat pipe and a method for manufacturing the same in view of the above problems.

The conventional heat pipe includes a metallic pipe, a wick structure and a working fluid. The metallic pipe has a sealed chamber. The wick structure is circumferentially adhered to the inner walls of the metallic pipe. The working fluid is filled in the sealed chamber of the metallic pipe. The inside of the wick structure is formed with a gas channel, thereby forming a heat pipe.

Although the conventional heat pipe can transfer the heat generated by a heat-generating source by means of the phase change between the vapor and liquid states of the working fluid, the wick structure provided on the inner wall of the metallic pipe may substantially narrow the gas channel within the metallic pipe. Furthermore, the internal surface of the wick structure is of a rugged surface, which may further obstruct the flowing speed of the internal gas. The above-mentioned problems are the primary factors causing the poor efficiency in dissipating the heat of the heat pipe. Therefore, it is an important issue to improve the conventional heat pipe.

SUMMARY

The present invention is to provide a heat pipe and a method for manufacturing the same. The interior of the metallic pipe is formed with a gas channel having a smooth surface, thereby enlarging the space of the gas channel and increasing the flowing speed of the internal gas. Thus, the heat-conducting efficiency can be improved greatly.

The present invention is to provide a heat pipe, which includes a metallic pipe, a wick structure and a working fluid. The interior of the metallic pipe has a sealing chamber. The metallic pipe is formed into an evaporating section, an adiabatic section and a condensing section along its lengthwise direction. The wick structure comprises a first wick structure and two elongate second wick structures connected to the first wick structure. The first wick structure is adhered to the inner wall of the evaporating section. The two second wick structures are separated from each other and adhered to the inner walls of the evaporating section, the adiabatic section and the condensing section. A gas channel is formed between the two second wick structures. The gas channel has a smooth surface. The working fluid is filled in the sealed chamber.

The present invention provides a method for manufacturing a heat pipe, including the steps of:

a) providing a metallic pipe with a sealed end;

b) inserting a core rod into the metallic pipe, a portion of the circumference of the core rod being adhered to the inner wall of the metallic pipe, a pitch being formed between the other portion of the circumference of the core rod and the inner wall of the metallic pipe;

c) filling metallic powder into the metallic pipe through the pitch;

d) sintering the metallic powder;

e) removing the core rod, forming inside the metallic pipe with a first wick structure and two elongate second wick structures connected to the first wick structure, a gas channel being formed between the two second wick structures, the gas channel having a smooth surface; and

f) filling a working fluid in the metallic pipe, degassing and sealing the metallic pipe.

The present invention has advantageous effects as follows. With different particle sizes and pore arrangement of the first and second wick structures, the condensed liquid within the heat pipe can flow back to the evaporating section rapidly, thereby overcoming the dry-out of the heat pipe efficiently. Further, with a flat profile of the heat pipe, it can be widely used in the electronic devices that are made more and more compact. Therefore, such a heat pipe can be used in various fields.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing the steps of the method for manufacturing the heat pipe of the present invention;

FIG. 2 is an exploded perspective view showing the metallic pipe and the core rod of the present invention;

FIG. 3 is an assembled view showing the core rod being inserted into the metallic pipe of the present invention;

FIG. 4 is a cross-sectional view taken along the line 4-4 in FIG. 3;

FIG. 5 is a cross-sectional view taken along the line 5-5 in FIG. 3;

FIG. 6 is a perspective view showing the external appearance of the heat pipe of the present invention;

FIG. 7 is a side cross-sectional view of FIG. 6;

FIG. 8 is a cross-sectional view showing another embodiment of the heat pipe of the present invention;

FIG. 9 is an exploded perspective view showing the metallic pipe and the core rod according to another method of the present invention;

FIG. 10 is an assembled view showing the core rod being inserted into the metallic pipe according to another method of the present invention;

FIG. 11 is a cross-sectional view taken along the line 11-11 in FIG. 10;

FIG. 12 is a cross-sectional view taken along the line 12-12 in FIG. 10;

FIG. 13 is a perspective view showing the external appearance of the heat pipe made according to another method of the present invention; and

FIG. 14 is a view showing the operating state of the heat pipe of the present invention being combined with a heat-dissipating fins assembly to dissipate the heat generated by a heat source.

DETAILED DESCRIPTION

The characteristics and technical contents of the present invention will be explained in more detail with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit the present invention.

Please refer to FIG. 7. The present invention provides a heat pipe 1, which includes a metallic pipe 10, a wick structure 20 and a working fluid 30.

The metallic pipe 10 is pre-formed to have a flat profile. The cross section of the metallic pipe 10 is enclosed by two flat plates 101 and two curved plates 102 (FIG. 5). The interior of the metallic pipe 10 has a sealed chamber 11 that is formed into an evaporating section 12, an adiabatic section 13 and a condensed section 14 along the lengthwise direction of the metallic pipe 10. The outer surface of the lower flat plate 101 of the evaporating section 12 protrudes to form a protrusion 103 (FIG. 4). The interior of the protrusion 103 is formed with a trough 104.

The wick structure 20 comprises a first wick structure 21 and two elongate second wick structures 22 connected to the first wick structure 21. The first wick structure 21 is adhered to the inner wall of the evaporating section 12. The two elongate second wick structures 22, 23 are separated from each other and adhered to the inner walls of the evaporating section 12, the adiabatic section 13 and the condensed section 14. A gas channel 24 (FIG. 6) is formed between the two second wick structures 22, 23. The gas channel has a smooth surface 241.

More specifically, the wick structure 20 is made by means of sintering metallic powder. The first wick structure 21 is formed in the trough 104 of the lower flat plate 101 (FIG. 4). Each of the second wick structures 22, 23 is formed on the curved plates 102 respectively, as shown in FIG. 5. The size of the metallic particles of the first wick structure 21 is smaller than that of the second wick structure 22. The size of the pores within the first wick structure 1 is smaller than size of the pores within each of the second wick structures 22, 23. The size of metallic particles of each of the second wick structures 22, 23 in the condensing section 14 is larger than that of each of the second wick structures 22, 23 in the evaporating section 12. The size of pores of each of the second wick structures 22, 23 in the condensing section 14 is larger than the size of pores of each of the second wick structures 22, 23 in the evaporating section 12.

The working fluid may be selected from pure water or other suitable fluids. The working fluid 30 is filled in the sealed chamber 11 of the metallic pipe 10.

Please refer to FIG. 1 to 7. The present invention provides a method for manufacturing a heat pipe, which includes the steps as follows.

In a step S100, a metallic pipe 10 having a sealed end 105 (FIG. 2) is provided. In this step, the metallic pipe 10 can be made by copper, copper alloy or other suitable materials. First, by means of a forming die (not shown), a circular metallic pipe 10 is pressed to form a flat profile. The flattened metallic pipe 10 is enclosed by two flat plates 101 and two curved plates 102. The outer surface of the lower flat plate 101 on the right side of the metallic pipe 10 is formed with a protrusion 103. The interior of the protrusion 103 is formed with a trough 104. The protrusion 103 is pressed and soldered to form a sealed end 105. One side of the metallic pipe 10 away from the sealed end 105 is provided previously with an open end 106.

In a Step S110, a core rod 5 is inserted into the metallic pipe 10. A portion of the circumference of the core rod 5 is adhered to the inner wall of the metallic pipe 10. A pitch A is formed between the other portion of the circumference of the core rod 5 and the inner wall of the metallic pipe 10, as shown in FIG. 3. In this step, an elongate rectangular core rod 5 is inserted into the metallic pipe 10. The upper and lower surfaces of the rectangular core rod 5 are clamped by the inner walls of the flat plate 101 of the metallic pipe 10 so as to be adhered to each other. A pitch A is formed between the left and right surfaces of the rectangular core rod 5 and the inner walls of the curved plates 102 of the metallic pipe 10. The pitch A is in communication with the trough 104.

In a step S120, metallic powder 6 is filled in the metallic pipe 10 through the pitch A (FIGS. 4 and 5). In this step, the powder made by metallic materials is filled in the metallic pipe 10 through the pitch A of the open end 16. In practice, the metallic powder 6 of smaller particles is first filled in the metallic pipe 10. Then, the metallic pipe 10 is shaken, so that the metallic powder 6 of smaller particles can be filled in the pitch A formed between the trough 104 and the lower portion of the metallic pipe (FIG. 4). Thereafter, the metallic powder 6 of larger particles is filled in the pitch A formed between the middle and upper portions of the metallic pipe 10. In this way, the middle and upper portions of the metallic pipe 10 are formed with a wick structure whose pores are smaller than those in the lower portion of the metallic pipe 10 (FIG. 5). In a step S130, the metallic powder 6 is sintered. In this step, the metallic powder 6 filled in the metallic pipe 10 is sintered and solidified by means of a sintering process.

In a step S140, the core rod 5 is removed. The interior of the metallic pipe 10 is formed with a first wick structure 21 and two elongate second wick structures 22, 23 connected to the first wick structure 21. A gas channel 24 is formed between the two second wick structures 22, 23. The gas channel 24 has a smooth surface 241 (FIG. 6). In this step, the core rod 5 can be shaken leftwards and rightwards, so that the connection between the wick structure 20 and the core rod 5 becomes loose. Then, the core rod 5 is removed from the interior of the metallic pipe 10. In this way, the interior of the metallic pipe 10 can be formed with the first wick structure 21, the second wick structures 22, 23 and the gas channel 24. The surface of the metallic pipe 10 adhered to the core rod 5 is formed with two smooth surfaces 241.

In a step S150, a working fluid 30 is filled in the metallic pipe 10. Then, the metallic pipe 10 is subjected to a degassing and sealing process (FIG. 7). In this step, the metallic pipe 10 is oriented upright or obliquely. Then, the working fluid 30 such as pure water is filled in the metallic pipe 10. Thereafter, by a heating and degassing device, the gas within the metallic pipe 10 is exhausted. Further, the open end 106 of the metallic pipe 10 is pressed and soldered to form a closed end. In this way, the sealed chamber 11 can be formed in the metallic pipe 10.

In addition, the method of the present invention further comprises a step S160 that can be performed after the step S140 or Step 150. In this step S160, a forming device is used to leveling the protrusion 103 (FIG. 8). In this step, a press or punch machine is used to press the protrusion 103 protruding from the underside of the flat plate 101, so that the protrusion 103 can be made flat and thus located in the same plane with the outer surface of the flat plate 101.

Please refer to FIGS. 9 to 13, which show another method of the present invention. In a step S300, a metallic pipe 10 having a closed end 15 is provided (FIG. 9). In this step, a circular metallic pipe 10 is pressed by a forming die (not shown) to have a flat profile. The flattened metallic pipe 10 is enclosed by two flat plates 101 and two curved plates 102.

In a step S310, a core rod 5′ is inserted into the metallic pipe 10. A portion of the circumference of the core rod 5′ is adhered to the inner wall of the metallic pipe 10. A pitch A is formed between the other portion of the circumference of the core rod 5′ and the inner wall of the metallic pipe 10 (FIG. 10). In this step, an elongate rectangular rod core 5′ is inserted into the metallic pipe 10. The front end of the rectangular rod 5′ is provided with a concave surface 51. The core rod 5′ is clamped by the inner wall of the flat plate 101 of the metallic pipe 10 so as to be adhered to each other. The metallic pipe 10 is formed with an accommodating trough B corresponding to the concave surface 51. A pitch A is formed between the left and right surfaces of the rectangular core rod 5′ and the inner walls of the curved plates 102 of the metallic pipe 10. The pitch A is in communication with the accommodating trough B.

In a step S320, metallic powder 6 is filled in the metallic pipe 10 through the pitch A (FIGS. 11 and 12). In a step S330, the metallic powder 6 is sintered. In a step S340, the core rod 55 is removed. The interior of the metallic pipe 10 is formed with a first wick structure 21 and two elongate second wick structures 22, 23 connected to the first wick structure 21. A gas channel 24 is formed between the two second wick structures 22, 23. The gas channel 24 has a smooth surface 241 (FIG. 13). In a step S350, a working fluid 30 is filled in the metallic pipe 10. The metallic pipe 10 is subjected to a degassing and sealing process (not shown). The steps S320 to S350 are substantially to the above-mentioned steps S120 to S150, and thus the description thereof is omitted for clarity.

Please refer to FIG. 14, which is a schematic view showing the operating state of the heat pipe of the present invention combined with a heat-dissipating fins assembly to dissipate the heat of a heat-generating source. The condensing section 14 of the heat pipe 1 of the present invention can be connected with a heat-dissipating fins assembly 7 that is constituted of a plurality of heat-dissipating fins. The evaporating section 12 of the heat pipe 1 is adhered to a heat-generating source 8. The heat generated by the heat-generating source 8 is transferred to the evaporating section 12, thereby heating and evaporating the internal working fluid 30. The gas flows rapidly from the gas channel 24 through the adiabatic section 13 to the condensing section 14, thereby taking away the heat of the heat-generating source 8. With the heat dissipation of the heat-dissipating fins assembly 7 to reduce the temperature of the gas, the gas reaching the condensing section 14 can be condensed to liquid state. Then, the condensed liquid flows back to the first wick structure 21 of the evaporating section 12 from each of the second wick structures 22, 23. Therefore, the continuous circulation of the working fluid forms the heat-transferring mechanism of the heat pipe.

According to the above, the heat pipe of the present invention and the method for manufacturing the same really achieve the desired objects and solve the drawbacks of prior art. Further, the present invention demonstrates novelty and inventive steps, and conforms to the requirements for an invention patent.