U.S. patent application number 13/850268 was filed with the patent office on 2014-06-19 for flat heat pipe and method for manufacturing the same.
This patent application is currently assigned to FOXCONN TECHNOLOGY CO., LTD.. The applicant listed for this patent is FURUI PRECISE COMPONENT (KUNSHAN) CO., LTD., FOXCONN TECHNOLOGY CO., LTD.. Invention is credited to SHENG-LIANG DAI, JIA-HONG WU.
Application Number | 20140166244 13/850268 |
Document ID | / |
Family ID | 50907179 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140166244 |
Kind Code |
A1 |
DAI; SHENG-LIANG ; et
al. |
June 19, 2014 |
FLAT HEAT PIPE AND METHOD FOR MANUFACTURING THE SAME
Abstract
An exemplary flat heat pipe includes a hollow tube and a wick
structure lining an inner surface of the tube. The tube includes an
evaporator section, an adiabatic section and a condenser section
defined in turn along a longitudinal direction thereof. The wick
structure includes a first wick portion located in the evaporator
section, a second wick portion located in the condenser section,
and a third wick portion extending longitudinally from the
evaporator section, through the adiabatic section to the condenser
section and communicating with the first wick portion and the
second wick portion. A capillary force of the first wick portion is
larger than that of the third wick portion, and a pore density of
the first wick portion is less than that of the third wick
portion.
Inventors: |
DAI; SHENG-LIANG; (Kunshan,
CN) ; WU; JIA-HONG; (New Taipei, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CO., LTD.; FURUI PRECISE COMPONENT (KUNSHAN)
FOXCONN TECHNOLOGY CO., LTD. |
New Taipei |
|
US
TW |
|
|
Assignee: |
FOXCONN TECHNOLOGY CO.,
LTD.
New Taipei
TW
FURUI PRECISE COMPONENT (KUNSHAN) CO., LTD.
Kunshan
CN
|
Family ID: |
50907179 |
Appl. No.: |
13/850268 |
Filed: |
March 25, 2013 |
Current U.S.
Class: |
165/104.26 ;
29/890.032 |
Current CPC
Class: |
Y10T 29/49353 20150115;
F28D 15/0233 20130101; F28D 15/046 20130101 |
Class at
Publication: |
165/104.26 ;
29/890.032 |
International
Class: |
F28D 15/04 20060101
F28D015/04; B21D 53/02 20060101 B21D053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2012 |
CN |
201210547166.6 |
Claims
1. A flat heat pipe for removing heat from a heat-generating
component in thermal contact therewith, the flat heat pipe
comprising: a hollow tube comprising an evaporator section, an
adiabatic section and a condenser section defined in turn along a
longitudinal direction thereof; and a wick structure lining an
inner surface of the tube, the wick structure comprising a first
wick portion located in the evaporator section, a second wick
portion located in the condenser section, and a third wick portion
extending longitudinally from the evaporator section, through the
adiabatic section to the condenser section and communicating with
the first wick portion and the second wick portion; wherein a
capillary force of the first wick portion is larger than that of
the third wick portion, and a pore density of the first wick
portion is less than that of the third wick portion.
2. The flat heat pipe of claim 1, wherein a capillary force of the
second wick portion is larger than that of the third wick portion
and less than that of the first wick portion, and a pore density of
the second wick portion is larger than that of the first wick
portion and less than that of the third wick portion.
3. The flat heat pipe of claim 1, wherein the third wick portion is
enclosed by the first wick portion and the second wick portion.
4. The flat heat pipe of claim 3, wherein the third wick portion is
disposed at a middle of one side of the tube, a bottom surface of
the third wick portion at the evaporator section is snugly attached
to an inner surface of the first wick portion, a bottom surface of
the third wick portion at the adiabatic and condenser sections is
snugly attached to an inner surface of the second wick portion, and
a top surface of the third wick portion is spaced from the first
wick portion and the second wick portion.
5. The flat heat pipe of claim 1, wherein the second wick portion
extends longitudinally from the adiabatic section to the condenser
section, and is formed on inner surfaces of the adiabatic section
and the condenser section.
6. The flat heat pipe of claim 5, wherein the first wick portion is
formed on an inner surface of the evaporator section, and an inner
end of the first wick portion contacts and communicates with an
inner end of the second wick portion.
7. The flat heat pipe of claim 1, wherein the second wick portion
is formed on the whole of the inner surface of the tube, and the
first wick portion is formed on an inner surface of the second wick
portion.
8. The flat heat pipe of claim 1, wherein the first wick portion
comprises sintered metal powder.
9. The flat heat pipe of claim 1, wherein the second wick portion
is a groove-type wick portion.
10. The flat heat pipe of claim 9, wherein the second wick portion
includes a plurality of elongated ridges and a plurality of
grooves, and each groove is defined between two corresponding
adjacent ridges.
11. The flat heat pipe of claim 1, wherein the third wick portion
is formed by weaving a plurality of metal wires.
12. The flat heat pipe of claim 1, wherein a length of the third
wick portion is equal to a sum of a length of the first wick
portion and a length of the second wick portion.
13. A method for manufacturing a flat heat pipe, the method
comprising: providing a hollow tube comprising an evaporator
section, an adiabatic section and a condenser section defined in
turn along a longitudinal direction thereof; etching an inner
surface of the condenser section to form a plurality of ridges and
a plurality of grooves, each groove defined between two
corresponding adjacent ridges, the ridges and the grooves
cooperatively forming a second wick portion; providing an amount of
metal powder and a mandrel, inserting the mandrel in the evaporator
section such that a gap is defined between an outer surface of the
mandrel and the inner surface of the evaporator section, filling
the metal powder in the gap, heating the tube with the mandrel and
the metal powder until the metal powder sinters to form a first
wick portion, and then drawing the mandrel out of the evaporator
section; and providing a plurality of metal wires and weaving the
metal wires to form a third wick portion, the third wick portion
extending longitudinally from the evaporator section, through the
adiabatic section to the condenser section and communicating with
the first wick portion and the second wick portion; wherein a
capillary force of the first wick portion is larger than that of
the third wick portion, and a pore density of the first wick
portion is less than that of the third wick portion.
14. The method of claim 13, wherein when the inner surface of the
condenser section is etched to form the plurality of ridges and the
plurality of grooves, inner surfaces of the adiabatic section and
condenser section are also etched, such that the plurality of
ridges and the plurality of grooves are formed in the condenser
section, the adiabatic section and condenser section.
15. The method of claim 14, wherein the first wick portion is
directly formed on the inner surface of the evaporator section.
16. The method of claim 14, wherein the whole of the inner surface
of the tube is etched.
17. The method of claim 16, wherein the first wick portion is
formed on an inner surface of the second wick portion.
18. The method of claim 17, wherein a particle diameter of each
grain of metal powder is larger than the transverse width of each
groove.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The disclosure generally relates to heat transfer
apparatuses such as those used in electronic equipment, and more
particularly to a flat heat pipe with stable and reliable
performance.
[0003] 2. Description of Related Art
[0004] Heat pipes are widely used in various fields for heat
dissipation purposes due to their excellent heat transfer
performance. One commonly used heat pipe includes a sealed tube
made of thermally conductive material with a working fluid
contained therein. The working fluid conveys heat from one end of
the tube, typically referred to as an evaporator section, to the
other end of the tube, typically referred to as a condenser
section. Preferably, a wick structure is provided inside the heat
pipe, lining an inner wall of the tube, and drawing the working
fluid back to the evaporator section after it condenses at the
condenser section.
[0005] During operation of the heat pipe in a typical application,
the evaporator section of the heat pipe maintains thermal contact
with a heat-generating electronic component. The working fluid at
the evaporator section absorbs heat generated by the electronic
component, and thereby turns to vapor. The generated vapor moves,
carrying the heat with it, toward the condenser section. At the
condenser section, the vapor condenses after the heat is
dissipated. The condensate is then drawn back by the wick structure
to the evaporator section where it is again available for
evaporation. For the condensate to be drawn back rapidly, the wick
structure located at the evaporator section must have a capillary
force larger than that of the wick structure located at the
condenser section. However, the capillary force of the wick
structure is uniform. Thus, the evaporator section is prone to
become dry.
[0006] What is needed, therefore, is a heat pipe to overcome the
above described shortcomings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a longitudinal, cross-sectional view of a flat
heat pipe according to a first embodiment of the present
disclosure.
[0008] FIG. 2 is a transverse, cross-sectional view of an
evaporator section of the flat heat pipe of FIG. 1, corresponding
to line II-II thereof.
[0009] FIG. 3 is a transverse, cross-sectional view of a condenser
section of the flat heat pipe of FIG. 1, corresponding to line
thereof.
[0010] FIG. 4 is a longitudinal, cross-sectional view of a flat
heat pipe according to a second embodiment of the present
disclosure.
[0011] FIG. 5 is a transverse, cross-sectional view of an
evaporator section of the flat heat pipe of FIG. 4, corresponding
to line V-V thereof.
[0012] FIG. 5 is a transverse, cross-sectional view of an
evaporator section of the flat heat pipe of FIG. 4, corresponding
to line V-V thereof.
[0013] FIG. 6 is a flowchart showing an exemplary method for
manufacturing the flat heat pipe of FIG. 1.
DETAILED DESCRIPTION
[0014] Embodiments of the present flat heat pipe will now be
described in detail below and with reference to the drawings.
[0015] Referring to FIGS. 1-3, a flat heat pipe 1 in accordance
with a first embodiment of the present disclosure is shown. The
flat heat pipe 1 includes a sealed, flat tube 30, a wick structure
50 lining an inner surface of the tube 30, and working fluid (not
shown) contained in the wick structure 50.
[0016] The tube 30 is made of metal or metal alloy with a high heat
conductivity coefficient, such as copper, copper-alloy, or other
suitable material. The tube 30 is elongated, and has an evaporator
section 11, an adiabatic section 13, and a condenser section 15
defined in that order along a longitudinal direction thereof. A
transverse section of the tube 30 is oval-shaped (or
racetrack-shaped). A longitudinal section of the tube 30 is
rectangular.
[0017] The wick structure 50 includes a first wick portion 51, a
second wick portion 53, and a third wick portion 55. The first wick
portion 51 is formed on an inner surface of the evaporator section
11. The second wick portion 53 extends longitudinally from the
adiabatic section 13 to the condenser section 15, and is formed on
inner surfaces of the adiabatic section 13 and the condenser
section 15. The second wick portion 53 contacts and communicates
with the first wick portion 51. The third wick portion 53 is
enclosed by the first wick portion 51 and the second wick portion
53. The third wick portion 53 extends longitudinally from the
evaporator section 11, and through the adiabatic section 13 to the
condenser section 15, and communicates with the first wick portion
51 and the second wick portion 53. A capillary force of the second
wick portion 53 is larger than that of the third wick portion 55
and less than that of the first wick portion 51. A pore density of
the second wick portion 53 is larger than that of the first wick
portion 51 and less than that of the third wick portion 55. In one
embodiment, sizes of the pores of the first, second and third wick
portions 51, 53, 55 are approximately the same. In such case, the
pore density can be measured according to the number of pores per
unit area/volume. In other embodiments, sizes of the pores of any
one or more of the first, second and third wick portions 51, 53, 55
differ. In such cases, the pore density can be measured according
to the total volume of pores per unit area/volume.
[0018] The first wick portion 51 is sintered metal powder, and has
the shape of a flattened annulus. An outer surface of the first
wick portion 51 is snugly attached to the inner surface of the
evaporator section 11.
[0019] The second wick portion 53 is a groove-type wick portion,
and a left end thereof connects and communicates with a right end
of the first wick portion 51. A length of the second wick portion
53 is larger than that of the first wick portion 51. The second
wick portion 53 includes a plurality of ridges (or elongated teeth)
531 and a plurality of grooves 533. Each groove 533 is defined
between two corresponding adjacent ridges 531.
[0020] In the illustrated embodiment, all the ridges 531 are
substantially the same size, and all the grooves 533 are
substantially the same size. A transverse cross-section of each
ridge 531 is trapezoidal, and a transverse cross-section of each
groove 533 is trapezoidal. A size of the transverse cross-section
of each ridge 531 is substantially the same as a size of the
transverse cross-section of each groove 533. Each ridge 531 tapers
from an end thereof far from a center of the tube 30 to an end
thereof nearer the center of the tube 30. Each groove 533 tapers
from an end thereof nearer the center of the tube 30 to an end
thereof far from the center of the tube 30. A transverse width of
each groove 533 at the end thereof nearer the center of the tube 30
is larger that of each ridge 531 at the end thereof nearer the
center of the tube 30.
[0021] The third wick portion 55 is disposed at a middle of one
side of the tube 30. A bottom surface of the third wick portion 55
at the evaporator section 11 is snugly attached to an inner surface
of the first wick portion 51. A bottom surface of the third wick
portion 55 at the adiabatic and condenser sections 13, 15 is snugly
attached to an inner surface of the second wick portion 53. A top
surface of the third wick portion 55 is spaced from the first wick
portion 51 and the second wick portion 53. The third wick portion
55 is formed by weaving a plurality of metal wires such as copper
wires and/or stainless steel wires. A length of the third wick
portion 55 is equal to a sum of a length of the first wick portion
51 and a length of the second wick portion 53.
[0022] In operation, the working fluid at the evaporator section 11
absorbs heat generated by one or more electronic components, and
thereby turns to vapor. The generated vapor moves, carrying the
heat with it, toward the condenser section 15. At the condenser
section 15, the vapor condenses after the heat is dissipated.
Because the pore density of the third wick portion 55 is larger
than that of the first wick portion 51, the condensate can rapidly
permeate into the third wick portion 55. Because the capillary
force of the first wick portion 51 is larger than that of the third
wick portion 55, the condensate in the third wick portion 55 can be
drawn back to the evaporator section 11 rapidly by the first wick
portion 51. Therefore, the evaporator section 11 of the flat heat
pipe 1 avoids becoming dry. Thus, the flat heat pipe 1 has stable
and reliable performance.
[0023] Referring to FIGS. 4-5, a flat heat pipe 1a in accordance
with a second embodiment of the present disclosure is shown. The
flat heat pipe 1a is similar to the flat heat pipe 1 of the first
embodiment. However, in the flat heat pipe 1a, a second wick
portion 53a is formed on the whole of the inner surface of the tube
30; and a first wick portion 51a is located at the evaporator
section 11 and is snugly attached to an inner surface of the second
wick portion 53a.
[0024] Referring to FIG. 6, an exemplary method for manufacturing
the flat heat pipe 1 includes the following steps:
[0025] In step S1, the tube 30 with an open end is provided.
[0026] In step S2, the inner surfaces of the adiabatic section 13
and condenser section 15 are etched to form the ridges 531 and the
grooves 533, and thus the second wick portion 53 is formed.
[0027] In step S3, an amount of metal powder and a mandrel are
provided. The mandrel is inserted in the evaporator section 11. A
gap is defined between an outer surface of the mandrel and the
inner surface of the evaporator section 11. The metal powder is
filled into the gap. The tube 30 with the mandrel and the metal
powder is heated at high temperature until the metal powder sinters
to form the first wick portion 51. The mandrel is then drawn out of
the tube 30. A particle diameter of each grain of metal powder is
larger than the transverse width of each groove 533.
[0028] In step S4, a plurality of metal wires is provided and
weaved to form the third wick portion 55. Then the third wick
portion 55 is disposed at the middle of one side of the tube 30,
with the bottom surface of the third wick portion 55 snugly
attached to inner surfaces of the first wick portion 51 and the
second wick portion 53, and the top surface of the third wick
portion 55 spaced from the first wick portion 51 and the second
wick portion 53.
[0029] In step S5, the working medium is injected into the tube 30,
the tube 30 is evacuated, and the open end of the tube 30 is
sealed. In this state, the flat heat pipe 1 is manufactured
completely.
[0030] A method for manufacturing the flat heat pipe 1a is similar
to that of the flat heat pipe 1, except that in step S2, the whole
of the inner surface of the tube 30 is etched to form the second
wick portion 53a. Then the first wick portion 51a is sintered on
the inner surface of the second wick portion 53a located at the
evaporator section 11, substantially according the third step
described above in relation to the flat heat pipe 1.
[0031] It is to be further understood 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 disclosure to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *