US20130248152A1

US20130248152A1 - Heat pipe with one wick structure supporting another wick structure in position

Info

Publication number: US20130248152A1
Application number: US13/721,049
Authority: US
Inventors: Ching-Bai Hwang; Chih-Peng Lee
Original assignee: Foxconn Technology Co Ltd
Current assignee: Foxconn Technology Co Ltd
Priority date: 2012-03-22
Filing date: 2012-12-20
Publication date: 2013-09-26
Also published as: TWI457528B; TW201339531A

Abstract

An exemplary heat pipe includes a tube, a first wick structure and a second wick structure received in the tube, and working liquid filling the tube. The first wick structure is disposed in an evaporating section of the tube. The second wick structure is located between the first wick structure, and supports the first wick structure partially contacting an inner face of the evaporating section of the tube. The first wick structure defines a gap between two opposite ends thereof. The second wick structure extends from the evaporating section through an adiabatic section to a condensing section of the tube.

Description

BACKGROUND

1. Technical Field
The disclosure generally relates to heat pipes and, particularly, to a heat pipe having two different wick structures.
2. Description of Related Art
With the continuing development of electronics technology, many electronic components are nowadays made in a small size but with a high operating frequency capability. When such electronic components operate inside a device, they generate much heat and require enhanced heat dissipation. In order to cool the electronic components, heat dissipation devices, such as heat pipes, are used to dissipate heat from the electronic components.
A typical heat pipe includes a tube, a wick structure received in the tube, and a working fluid sealed in the tube. The wick structure is generally attached on an entire inner wall of the tube as an elongated cylinder. The typical heat pipe has some problems which limit the heat transferring capability thereof. Firstly, when the heat pipe is manufactured, the cylindrical wick structure may not have intimate contact with the inner wall of the tube during insertion of the wick structure into the tube. Therefore after sintering (or another kind of fixing method) to attach the wick structure to the tube, some parts of the wick structure may be spaced from the inner wall of the tube. Because these parts of the wick structure are not in contact with the inner wall of the tube, such parts may significantly interrupt the capillary transport of liquid working fluid along the wick structure to an evaporating section of the heat pipe.
Secondly, the wick structure covers the whole inner wall of the tube, and therefore the diameter of an inner chamber of the heat pipe is reduced. The inner chamber of the heat pipe acts as a vapor passage of the heat pipe, and thus the space available for passage of vapor is reduced. For some thin heat pipes, the small space for vapor passage significantly limits transport of vaporized working fluid from the evaporating section to a condensing section of the heat pipe. Thus the heat transferring capability of the heat pipe is reduced.
What is needed, therefore, is a means which can address the limitations described.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments 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 embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the various views.

FIG. 1 is an abbreviated, longitudinal cross-section of a heat pipe in accordance with a first embodiment of the present disclosure.

FIG. 2 is a transverse cross-section of the heat pipe of FIG. 1, corresponding to a line II-II thereof.

FIG. 3 is similar to FIG. 2, but showing a transverse cross-section of a heat pipe in accordance with a second embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a heat pipe 100 in accordance with a first embodiment of the present disclosure is shown. The heat pipe 100 includes a longitudinal tube 10, a first wick structure 30 and a second wick structure 40 fixed in the tube 10, and working liquid 20 contained within the tube 10.
The tube 10 is made of a heat conductive material such as copper, aluminum or alloy thereof. The tube 10 includes a bottom wall 101, a top wall 103 parallel to the bottom wall 101, and a first side wall 105 and a second side wall 107 interconnecting the top wall 103 and the bottom wall 101. A distance between the top wall 103 and the bottom wall 101 is less than that between the first side wall 105 and the second side wall 107. The tube 10 defines an elongated chamber 50 therein. The tube 10 includes an evaporating section 110 at an end thereof, a condensing section 120 at an opposite end thereof, and an adiabatic section 130 between the evaporating section 110 and the condensing section 120.
The first wick structure 30 is disposed on an inner face of the tube 10 at the evaporating section 110. The first wick structure 30 may be formed by sintering metal powder on the inner face of the tube 10, or by inserting curved woven mesh on the inner face of the tube 10, or by other suitable methods. In this embodiment, the first wick structure 30 is only disposed at the evaporating section 110 without extending to the adiabatic section 130 and the condensing section 120. Thus the first wick structure 30 occupies a relatively small space of a vapor passage (i.e., the chamber 50) of the heat pipe 10, and thereby facilitates the flow of vaporized working liquid 20 within the tube 10. The first wick structure 30 has a U-shaped cross section, with a gap 301 defined between two opposite ends thereof. The first wick structure 30 partially covers the inner face of the evaporating section 110 of the tube 10. In detail, the first wick structure 30 includes a bottom portion 302 contacting the bottom wall 101, a side portion 304 contacting the second side wall 107, and a top portion 303 contacting the top wall 103 of the tube 10. The gap 301 is located between the bottom portion 302 and the top portion 303, and is adjacent to the first side wall 105 of the tube 10.
The second wick structure 40 extends throughout a length of the tube 10, from the evaporating section 110 through the adiabatic section 130 to the condensing section 120. The second wick structure 40 may be made of woven mesh, bunched fiber, or other suitable material. The second wick structure 40 is sandwiched between the top portion 303 and the bottom portion 302 of the first wick structure 30, thereby providing sufficient support for the first wick structure 30. Thus, the first wick structure 30 can intimately contact the inner face of the tube 10, without significant spaces existing between the inner face of the tube 10 and the first wick structure 30. The second wick structure 40 is positioned along a central axis I of the tube 10. In one embodiment, the second wick structure 40 is hollow, and thereby defines a channel 401 therethrough. The channel 401 may function as another vapor passage within the second wick structure 40, in addition to the vapor passage outside and surrounding the second wick structure 40. Therefore, the vaporized working liquid 20 can be transferred to the condensing section 120 more quickly. In other embodiments, the second wick structure 40 can be a solid wick structure without the channel 401.
Alternatively, the gap 301 of the first wick structure 30 may be defined in other positions of the first wick structure 30 according to different requirements. For example, FIG. 3 shows a gap 301 a of a first wick structure 30 a being located at the top wall 103 adjacent to the first side wall 105 of the tube 10. The first wick structure 30 a includes a top portion 303 a, a side portion 304 a, a bottom portion 302 a, and another side portion 305 a. The side portion 305 a is located opposite to the side portion 304 a, and extends from the bottom portion 302 a towards an end of the top portion 303 a. The side portion 305 a contacts the first side wall 105 of the tube 10. The gap 301 a is located between the side portion 305 a and the end of the top portion 303 a.
It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, 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

What is claimed is:

1. A heat pipe comprising:

a tube comprising an evaporating section, a condensing section, and an adiabatic section interconnecting the evaporating section and the condensing section;

a first wick structure partially covering an inner face of the evaporating section of the tube and intimately contacting the inner face, the first wick structure defining a gap between two opposite ends thereof;

a second wick structure between the first wick structure and supporting the first wick structure in position intimately contacting the inner face of the evaporating section of the tube; and

working liquid received within the tube.

2. The heat pipe of claim 1, wherein the tube comprises a top wall, a bottom wall spaced from the top wall, and a first side wall and a second side wall interconnecting the top wall and the bottom wall, the top wall, the bottom wall, the first side wall and the second wall cooperatively defining a chamber, the chamber having the first wick structure, the second wick structure and the working liquid received therein.

3. The heat pipe of claim 2, wherein a distance between the top wall and the bottom wall is less than that between the first side wall and the second side wall.

4. The heat pipe of claim 2, wherein the first wick structure comprises a top portion contacting the top wall of the tube, a bottom portion contacting the bottom wall of the tube, and a side portion contacting the second side wall of the tube.

5. The heat pipe of claim 4, wherein the gap is defined between an end of the top portion and an end of the bottom portion of the first wick structure.

6. The heat pipe of claim 5, wherein the gap is located at the first side wall of the tube.

7. The heat pipe of claim 4, wherein the first wick structure further comprises another side portion contacting the first side wall of the tube.

8. The heat pipe of claim 7, wherein the gap is defined between an end of the top portion and an end of the another side portion of the first wick structure.

9. The heat pipe of claim 8, wherein the gap is located at the top wall of the tube adjacent to the first side wall of the tube.

10. The heat pipe of claim 4, wherein the second wick structure is sandwiched between the top portion and the bottom portion of the first wick structure.

11. The heat pipe of claim 1, wherein the first wick structure does not extend to the adiabatic section and the condensing section.

12. The heat pipe of claim 1, wherein the second wick structure extends from the evaporating section through the adiabatic section to the condensing section.

13. The heat pipe of claim 1, wherein the second wick structure is disposed along a central axis of the tube.

14. The heat pipe of claim 1, wherein the second wick structure defines a vapor passage therein.

15. The heat pipe of claim 1, wherein the second wick structure is made of material different from that of the first wick structure.

16. A heat pipe comprising:

a tube comprising an evaporating section, a condensing section and an adiabatic section interconnecting the evaporating section and the condensing section;

a first wick structure disposed in the evaporating section only of the tube and intimately contacting an inner face of the evaporating section, the first wick structure being discontinuous along a transverse circumferential path of the tube;

a second wick structure between the first wick structure and supporting the first wick structure in position intimately contacting the inner face of the tube, the second wick structure extending along a longitudinal direction of the tube perpendicular to the circumferential path of the tube; and

working liquid received in the tube.

17. The heat pipe of claim 16, wherein the first wick structure defines a gap at a discontinuous position thereof, the gap being located between two opposite ends of the first wick structure.

18. The heat pipe of claim 17, wherein the gap is located corresponding to a lateral side of the tube.

19. The heat pipe of claim 17, wherein the gap is located corresponding to a top side of the tube adjacent to a lateral side of the tube.

20. The heat pipe of claim 17, wherein the second wick structure defines a vapor passage therein.