US20070267178A1

US20070267178A1 - Heat pipe

Info

Publication number: US20070267178A1
Application number: US11/309,346
Authority: US
Inventors: Chuen-Shu Hou; Chao-Nien Tung; Tay-Jian Liu
Original assignee: Foxconn Technology Co Ltd
Current assignee: Foxconn Technology Co Ltd
Priority date: 2006-05-19
Filing date: 2006-07-28
Publication date: 2007-11-22
Also published as: CN101074852A; CN100513974C

Abstract

A heat pipe includes a casing (100) having an inner surface. A capillary wick (200) is attached to the inner surface of casing. The casing includes an evaporating section (400) for receiving heat, a condensing section (600) for releasing the heat and an adiabatic section (500) for transferring the heat from the evaporating section to the condensing section. The evaporating and condensing sections are made of metal material and the adiabatic section is made of nonmetallic material.

Description

1. FIELD OF THE INVENTION

The present invention relates generally to a heat pipe as heat transfer/dissipating device, and more particularly to a heat pipe having an adiabatic section made of nonmetallic material.

2. DESCRIPTION OF RELATED ART

It is well known that a heat pipe is generally a vacuum-sealed pipe. A porous wick is provided on an inner face of the pipe, and the pipe is filled with at least a phase changeable working media employed to carry heat. Generally, according to positions from which heat is input or output, the heat pipe has three sections, an evaporating section, a condensing section and an adiabatic section between the evaporating section and the condensing section.
In use, the heat pipe transfers heat from one place to another place mainly by virtue of phase change of the working media taking place therein. Generally, the working media is liquid such as alcohol, water and the like. When the working media in the evaporating section of the heat pipe is heated up, it evaporates, and a pressure difference is thus produced between the evaporating section and the condensing section in the heat pipe. As a result vapor with high enthalpy flows to the condensing section and condenses there. Then the condensed liquid reflows to the evaporating section along the wick structure. This evaporating/condensing cycle continues in the heat pipe; consequently, heat can be continuously transferred from the evaporating section to the condensing section. Due to the continual phase change of the working media, the evaporating section is kept at or near the same temperature as the condensing section of the heat pipe.
In many cases, the heat pipe is required to be bent into a curved one or pressed into a flattened one in order to be applicable in electronic devices that have very limited mounting space, for example, in some portable electronic devices such as notebook computers. However, during said process, the wick in the heat pipe is prone to separate from the pipe and accordingly is damaged, which adversely affects heat transfer capability of the heat pipe.
Furthermore, the conventional heat pipes are entirely made of highly thermally conductive material such as copper. However, the price of copper dramatically rises in recently years, which leads to a dramatic increase of the cost of the heat pipe accordingly.
Therefore, it is desirable to provide a heat pipe which can over the shortcomings of the conventional art.

SUMMARY OF THE INVENTION

The present invention relates to a heat pipe. The heat pipe includes a casing having an inner surface. A capillary wick is attached to the inner surface of the casing. The casing includes an evaporating section for receiving heat, a condensing section for releasing the heat and an adiabatic section for transferring the heat from the evaporating section to the condensing section. The evaporating and condensing sections are made of metal material and the adiabatic section is made of nonmetallic material.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present device can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a longitudinally cross-sectional view of a heat pipe in accordance with a first embodiment of the present invention;

FIG. 2 is a longitudinally cross-sectional view of a heat pipe in accordance with a second embodiment of the present invention.

FIG. 3 is a transversely cross-sectional view of an adiabatic section of a heat pipe in accordance with a third embodiment of the present invention; and

FIG. 4 is an enlarged, perspective view of an expanded portion of an adiabatic section of a heat pipe in accordance with a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a heat pipe in accordance with one embodiment of the present invention. The heat pipe includes a casing 100, a working fluid (not shown) contained in the casing 100 and a capillary wick 200 arranged in an inner surface of the casing 100. A vapor channel 300 is defined along an axial direction of the heat pipe and is located at a center of the casing 100. The vapor channel 300 is surrounded by an inner surface of the capillary wick 200 so as to guide vapor to flow therein. In this embodiment, the casing 100 includes an evaporating section 400 at one end, a condensing section 600 at the other end and an adiabatic section 500 arranged between the evaporating section 400 and the condensing section 600. The evaporating section 400 and the condensing section 600 are made of highly thermally conductive metal material such as copper, aluminum, copper alloys or aluminum alloys. The inner surface of the casing 100 at evaporating and condensing sections 400, 600 may be smooth or may define a plurality of micro-grooves therein. The adiabatic section 500 acts as a passage of the condensed liquid, being made of nonmetallic material such as plastic, resin, rubber, fiber or ceramic. The nonmetallic material of the adiabatic section 500 can be formed into a desired shape easily. The nonmetallic material of the adiabatic section 500 may be a compound material of macromolecule material and inorganic material. A cross section of the adiabatic section 500 may be round, square or other shape, depending on the shape of the heat pipe.
Along a longitudinal direction of the casing 100, the capillary wick 200 has a multi-layer structure, which includes in sequence a first layer 240, a second layer 250 and a third layer 260. In this embodiment, the first, second and third layers 240, 250, 260 correspond to the evaporating, adiabatic and condensing sections 400, 500, 600 of the casing 100, respectively. The first and third layers 240, 260 each have a sintered powder wick. The second layer 250 corresponding to the adiabatic section 500 has a groove-type wick. Alternatively, the first and third layers 240, 260 each may be a fine-mesh wick, bundles of fiber wick, a honeycombed wick, or a combination thereof. The second layer 250 may be the fine-mesh wick, the bundles of fiber wick, the honeycombed wick, a fin-type wick (shown in FIG. 3), a pole-type wick (shown in FIG. 4), or a combination thereof. Referring to FIG. 3, the fin-type wick consists of a plurality of fins 152 extending from the inner surface of the adiabatic section 500. Referring to FIG. 4, the pole-type wick consists of a plurality of parallel micro-poles 154 extending from the inner surface of the adiabatic section 500.
Thus a cost and weight of the heat pipe is reduced due to the use of the nonmetallic material of the adiabatic section 500.
FIG. 2 illustrates a heat pipe according to a second embodiment of the present invention. The heat pipe of the second embodiment is similar to that of the previous first embodiment. However, an adiabatic section 500 a replaces the adiabatic section 500 of the previous first embodiment. The adiabatic section 500 a is bent to form a U-shaped configuration. The adiabatic section 500 a is made of macromolecule material having good pliability. The adiabatic section 500 a and the capillary wick 250 a are integrally molded as a single piece. During the bending process, the capillary wick 250 a does not separate from the inner surface of the adiabatic section 500 a and, accordingly, is not damaged.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A heat pipe comprising:

a casing having an inner surface and defining an evaporating section for receiving heat, a condensing section for releasing the heat and an adiabatic section located between the evaporating and condensing sections for transferring the heat from the evaporating section to the condensing section, the evaporating and condensing sections being made of metal material, the adiabatic section being made of nonmetallic material;

a working fluid received in the casing and evaporated into vapor in the evaporating section and condensed into liquid in the condensing section; and

a capillary wick applied to the inner surface of the casing.

2. The heat pipe of claim 1, wherein the adiabatic section is made of macromolecule material.

3. The heat pipe of claim 1, wherein the nonmetallic material of the adiabatic section is one of plastic, resin, rubber, fiber and ceramic.

4. The heat pipe of claim 1, wherein the adiabatic section is made of a compound material of macromolecule material and inorganic material.

5. The heat pipe of claim 1, wherein the capillary wick at the evaporating and condensing sections is a sintered powder wick, and the capillary wick at the adiabatic section is a groove-type wick.

6. The heat pipe of claim 1, wherein the capillary wick at the evaporating and condensing sections is one of a sintered powder wick, a fine-mesh wick, bundles of fiber wick, a honeycombed wick, and a combination thereof.

7. The heat pipe of claim 1, wherein the capillary wick at the adiabatic section is one of a fine-mesh wick, bundles of fiber wick, a honeycombed wick, a fin-type wick, a pole-type wick, and a combination thereof.

8. The heat pipe of claim 7, wherein the fin-type wick at the adiabatic section consists of a plurality of fins extending from the inner surface of the adiabatic section.

9. The heat pipe of claim 7, wherein the pole-type wick at the adiabatic section consists of a plurality of parallel micro-poles extending from the inner surface of the adiabatic section.

10. A heat pipe comprising:

a casing having an evaporating section for receiving heat, a condensing section for releasing the heat and an adiabatic section between the evaporating and condensing sections, wherein the adiabatic section is made of nonmetallic material; and

a capillary wick disposed on an inner surface of the casing, the capillary wick consisting of a first layer corresponding to the evaporating section, a second layer corresponding to the adiabatic section and a third layer corresponding to the condensing section, wherein the second layer has a structure different from that of the first and third layers.

11. The heat pipe of claim 10, wherein the second layer of the capillary wick is integrally formed with the adiabatic section of the casing as a monolithic piece.

12. The heat pipe of claim 11, wherein the second layer of the capillary wick comprises a plurality of fins extending from the inner surface of the adiabatic section of the casing.

13. The heat pipe of claim 11, wherein the second layer of the capillary wick comprises a plurality of micro poles extending from the inner surface of the adiabatic section of the casing.

14. The heat pipe of claim 11, wherein the nonmetallic material is selected from one of plastic, resin, rubber, fiber and ceramic.