Heat pipe manufacturing method and heat pipe thereof   

Abstract: A heat pipe includes a step pipe and a sintered powder structure. The inner wall of the step pipe has a plurality of grooves. The step pipe has an evaporating section and two condensing sections. The condensing sections are on the two ends of the step pipe, respectively. The evaporating section lies between the two condensing sections. The inner spaces of the two condensing sections and the evaporating section are interconnected. The peripheral dimension of the evaporating section is larger than the peripheral dimension of each of the condensing sections. The sintered powder structure is bounded inside each of the condensing sections, improving the heat pipe's inner air flow rate and heat conduction efficiency.

1. Technical Field

The present invention generally relates to a heat pipe, and more particularly, to a method of manufacturing a heat pipe and a heat pipe thereof.

2. Related Art

The exacerbating problems caused by electronic heat sources can be resolved by using heat pipes to dissipate heat in electronic products. Replacing cooling structures formed by cooling fins with heat pipes is apparently the future development trend. In addition to fit in with the premises that electronic products need to be light, thin, short, and small, it\'s also desirable to further enhance a heat pipe\'s heat-conduction efficiency.

A conventional heat pipe generally includes a round pipe with a fixed diameter, a capillary structure, and a working fluid. The round pipe has a containing chamber in its interior. The capillary structure is set inside the containing chamber and stuck to the inner surface of the pipe. The working fluid is filled in the containing chamber and accumulated in the capillary structure. As a whole, these parts form a conventional heat pipe.

However, because the diameter of the round pipe is fixed, the inner working fluid could not speed up the heat dissipation rate when it evaporates. Therefore, the heat pipe\'s heat conduction efficiency is relatively limited. Furthermore, because the capillary structure is a homogeneous structure, its flow-back rate is relatively low and hence might not prevent the heat pipe from drying out. In addition, because the heat pipe\'s evaporation section has a small sectional area, the heat pipe cannot provide a large area to contact with the heat source. Therefore, the heat pipe can only generate a small amount of steam, and the amount is insufficient to prevent heat accumulation. As a result, it\'s difficult to effectively improve the conventional heat pipe\'s heat dissipation efficiency.

SUMMARY

Embodiments of the present invention provide a method of manufacturing a heat pipe and a heat pipe thereof. Because in each of these embodiments the peripheral dimension of an evaporating section is different from the peripheral dimensions of a plurality of condensing sections, the inner air\'s flow rate is increased and the heat conduction efficiency is improved.

To achieve the aforementioned objectives, an embodiment of the present invention provides a method of manufacturing a heat pipe. The method includes the following steps: a) providing a hollow pipe, an inner wall of the hollow pipe having a plurality of grooves; b) shrinking a part of the hollow pipe so as to convert the hollow pipe into a step pipe having varying peripheral dimensions; c) inserting an insertion rod into the step pipe, and filling a metal powder into a space between the step pipe and the insertion rod; and d) after step c), sintering the step pipe and the insertion rod so as to form a sintered powder structure on an inner wall of the step pipe.

Another embodiment of the present invention provides a heat pipe. The heat pipe includes a step pipe and a sintered powder structure. An inner wall of the step pipe has a plurality of grooves. The step pipe has an evaporating section and two condensing sections. The two condensing sections are on two ends of the step pipe, respectively. The evaporating section lies between the two condensing sections. The inner spaces of the two condensing sections and the evaporating section are interconnected. The peripheral dimension of the evaporating section is larger than the peripheral dimension of each of the condensing sections. The sintered powder structure is bounded inside each of the condensing sections.

The embodiments have the following advantages. The composite capillary structure in each of the condensing sections improves the liquid flow-back rate and hence prevents dry out. The relatively larger sectional area of the evaporating section increases the contact area between the evaporating section and a heat source, allows more steam to be generated, and hence improves the heat dissipation efficiency. Because the sectional area of the evaporating section is larger than the sectional areas of the condensing sections and because sectional area is inversely proportional to flow rate, when the working fluid receives enough heat and evaporates, the resulting air will have a higher flow rate.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flowchart of a heat pipe manufacturing method according to an embodiment of the present invention;

FIG. 2 shows a perspective view of a hollow pipe;

FIG. 3 shows a perspective view of the hollow pipe after being shaped;

FIG. 4 shows a sectional view of a step pipe inserted with an insertion rod;

FIG. 5 shows a sectional view of the step pipe and a sintered powder structure;

FIG. 6 shows a perspective view of the heat pipe;

FIG. 7 shows a sectional view of the heat pipe;

FIG. 8 shows a perspective view of the heat pipe after being flattened;

FIG. 9 shows a sectional view of the heat pipe after being flattened;

FIG. 10 shows a section view along the line 10-10 of FIG. 9;

FIG. 11 shows a section view along the line 11-11 of FIG. 9;

FIG. 12 shows a sectional view of an evaporating section of a heat pipe according to another embodiment of the present invention; and

FIG. 13 shows a sectional view of an evaporating section of a heat pipe according to further another embodiment of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 1 to FIG. 5. An embodiment of the present invention provides a method of manufacturing a heat pipe. The method includes the following steps.

Step a) Provide a hollow pipe 10. The hollow pipe 10 has a plurality of grooves 12 on its inner wall. Please refer to FIG. 2. In this embodiment, the hollow pipe 10 is composed of, but not limited to, materials with good heat-conductivity and ductility, such as copper and copper alloy. The hollow pipe 10 in this embodiment is a straight round pipe with a containing chamber 11 in its interior. The inner wall of the hollow pipe 10 has a plurality of grooves 12 that are parallel to each other. A convex stripe 13 lies between each pair of adjacent grooves 12. Each of the grooves 12 is parallel to an axis of the hollow pipe 10, and extends from one end of the hollow pipe 10 to the other end.

Step b) Shrink some parts of the hollow pipe 10 so as to convert the hollow pipe 10 into a step pipe 10a with varying peripheral dimensions. Please refer to FIG. 3, at this step, the hollow pipe 10 with fixed peripheral dimension is placed in a shaping mold, which is not shown in the figure. This shaping mold is used to shrink the areas on the two ends of the hollow pipe 10, causing the peripheral dimension in the middle area to be larger than the peripheral dimensions on the two ends.

Step c) Insert an insertion rod 5 into the step pipe 10a, and fill in the space between the step pipe 10a and the insertion rod 5 with metal powder 20. Please refer to FIG. 4, at this step the insertion rod 5 is inserted into a terminal area inside the step pipe 10a. Then the metal powder 20 is stuffed between the step pipe 10a and the insertion rod 5. In this embodiment, the metal powder 20 is stuffed inside the shrunk areas on the two ends of the step pipe 10a.

Step d) Sinter the step pipe 10a and the insertion rod 5 that are combined at step c), causing a sintered powder structure 20a to be formed on the inner wall of the step pipe 10a. Please refer to FIG. 5, at this step, the step pipe 10a and the insertion rod 5 are sintered in a sintering furnace, which is not depicted in the figure. Then, the insertion rod 5 is extracted from the step pipe 10a. The metal powder 20 remains on the two ends of the step pipe 10a and form a sintered powder structure 20a.

In addition, the embodiment can further include a step e) after step d). At step e) the step pipe 10a is sealed up, filled with a working fluid 30, and degassed. Please refer to FIG. 6 and FIG. 7, at this step, a sealing apparatus, which is not depicted in the figure, is used to solder and seal an end of the step pipe 10a. Then, the working fluid 30 is filled into the step pipe 10a through the not yet sealed end of the step pipe 10a. Next, the step pipe 10a that is filled with the working fluid 30 is degassed. The other end of the step pipe 10a is then soldered and sealed. Eventually, the heat pipe 1 of the embodiment is finished, where the heat pipe 1 is now a straight step pipe with round traverse sections.

Moreover, the embodiment can further include a step f) after step e). At step f), the step pipe 10a is flattened. Please refer to FIG. 8, at this step, a tool, which is not depicted in the figure, is used to press the heat pipe 1. As a result, the heat pipe 1 becomes a straight step pipe with flat traverse sections.

Please refer to FIG. 8 to FIG. 11. Another embodiment of the present invention provides a heat pipe that includes a step pipe 10a and a sintered powder structure 20a. The inner wall of the step pipe 10a has a plurality of grooves 12 that are parallel to each other. A convex stripe 13 lies between each pair of adjacent grooves 12. The step pipe 10a has an evaporating section 101 and two condensing sections 102 and 103. The two condensing sections 102 and 103 are on two different ends of the step pipe 10a, respectively. The evaporating section 101 lies between the two condensing sections 102 and 103. The evaporating section 101 can have a thermal contact with an electronic heat source, which is not depicted in the figure. Each of the condensing sections 102 and 103 can conduct heat to cooling components such as cooling fins and cooling blocks, which are not depicted in the figure. The interior of each of the condensing sections 102 and 103 is connected to the interior of the evaporating section 101. The peripheral dimension of the evaporating section 101 is larger than the peripheral dimensions of the condensing sections 102 and 103. In other words, the cross section of the evaporating section 101 is larger than the cross sections of the condensing sections 102 and 103. The sintered powder structure 20a is inside the condensing section 102 or 103 or both.

In addition to the aforementioned configuration, the followings are some alternative configurations. In a first alternative, the evaporating section 101 is round and the condensing sections 102 and 103 are flat. In a second alternative, the evaporating section 101 is flat and the condensing sections 102 and 103 are round. In a third alternative, the evaporating section 101 is semicircular, as shown in FIG. 12, and the condensing sections 102 and 103 are round. In a fourth alternative, the evaporating section 101 is semicircular and the condensing sections 102 and 103 are flat. Moreover, in FIG. 12, each of the grooves 12 in the evaporating sections 101 is filled with the sintered powder structure 20a. The sintered powder structure 20a stores much working fluid 30 to prevent dry-out.

Please refer to FIG. 13, which shows another embodiment of the evaporating section 101 of the heat pipe 1. In this embodiment, a mesh 40 is surrounded by the convex stripes 13, and a supporting component 45 is surrounded by the mesh 40. In other words, the mesh 40 is clipped between the convex stripes 13 and the supporting component 45. The supporting component 45 in this embodiment is a helical spring. This embodiment allows the evaporating section 101 to store much working fluid 30 to prevent dry-out.

The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.