U.S. patent application number 11/556613 was filed with the patent office on 2008-05-08 for heat pipe with variable grooved-wick structure and method for manufacturing the same.
This patent application is currently assigned to FOXCONN TECHNOLOGY CO., LTD.. Invention is credited to CHANG-SHEN CHANG, JUEI-KHAI LIU, HSIEN-SHENG PEI, CHAO-HAO WANG.
Application Number | 20080105406 11/556613 |
Document ID | / |
Family ID | 39358746 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080105406 |
Kind Code |
A1 |
CHANG; CHANG-SHEN ; et
al. |
May 8, 2008 |
HEAT PIPE WITH VARIABLE GROOVED-WICK STRUCTURE AND METHOD FOR
MANUFACTURING THE SAME
Abstract
A heat pipe (10) includes a casing (11), a plurality of grooves
(12, 13) defined in the casing, and working fluid contained in the
casing. The casing includes a first portion (14) and a second
portion (15) having a smaller diameter than the first portion. The
grooves (12) at the first portion of the casing have greater apex
angles and smaller groove width than those of the grooves (13) at
the second portion. A method for manufacturing the heat pipe
includes the steps of: providing a casing with a plurality of
grooves defined in an inner wall thereof; shrinking a diameter of
one portion of the casing to enable the portion to function as an
evaporator section of the heat pipe; vacuuming and placing a
predetermined quantity of working fluid in the casing; sealing the
casing to obtain the heat pipe.
Inventors: |
CHANG; CHANG-SHEN;
(Tu-Cheng, TW) ; LIU; JUEI-KHAI; (Tu-Cheng,
TW) ; WANG; CHAO-HAO; (Tu-Cheng, TW) ; PEI;
HSIEN-SHENG; (Tu-Cheng, TW) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. CHENG-JU CHIANG
458 E. LAMBERT ROAD
FULLERTON
CA
92835
US
|
Assignee: |
FOXCONN TECHNOLOGY CO.,
LTD.
Tu-Cheng
TW
|
Family ID: |
39358746 |
Appl. No.: |
11/556613 |
Filed: |
November 3, 2006 |
Current U.S.
Class: |
165/104.26 ;
165/146 |
Current CPC
Class: |
B23P 15/26 20130101;
F28D 15/0283 20130101; F28D 15/046 20130101; B23P 2700/09
20130101 |
Class at
Publication: |
165/104.26 ;
165/146 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. A heat pipe comprising: a casing comprising a first portion and
a second portion having a smaller diameter than the first portion;
a plurality of grooves defined in an inner wall of the casing; and
a predetermined quantity of bi-phase working fluid contained in the
casing; wherein the grooves at the first portion of the casing have
smaller groove width than that of the grooves at the second
portion.
2. The heat pipe of claim 1, wherein the grooves extends along a
central axis of the casing.
3. The heat pipe of claim 1, wherein the grooves at the first
portion of the casing have greater apex angles than that of the
grooves at the second portion.
4. The heat pipe of claim 1, wherein the first portion is an
evaporator section of the heat pipe, whilst the second section is a
condenser section of the heat pipe.
5. The heat pipe of claim 4, wherein the evaporator section is
disposed at an end of the heat pipe.
6. The heat pipe of claim 4, wherein the evaporator section is
disposed at a middle portion of the heat pipe.
7. The heat pipe of claim 1 further comprising a transition section
disposed between the first portion and the second portion, a
diameter of the transition section being gradually decreased from
the second portion towards the first portion.
8. The heat pipe of claim 1, wherein the casing of the heat pipe is
flat in profile.
9. A method for manufacturing a heat pipe with variable
grooved-wick structure comprising the steps of: providing a casing
with a plurality of tiny grooves defined in an inner wall thereof;
shrinking a diameter of one portion of the casing via a shrinkage
tool to enable it to function as an evaporator section of the heat
pipe; vacuuming and placing a predetermined quantity of working
fluid in the casing; and sealing the casing to obtain the heat
pipe.
10. The method as described in claim 9, wherein the grooves are
axially carved in the inner wall of the casing.
11. The method as described in claim 9, wherein the shrinkage tool
is a high speed spinning tube shrinkage tool, the shrinkage process
of the evaporator section comprises the step of controlling the
high speed spinning tube shrinkage tool to move towards the
evaporator section of the casing along a central longitudinal axis
thereof so as to shrink the diameter thereof.
12. The method as described in claim 11, wherein the high speed
spinning tube shrinkage tool comprises a tapered portion which
enables to compress an outer wall of the evaporator section so as
to shrink the diameter thereof and a guiding portion which guides
the movement of the high speed spinning tube shrinkage tool.
13. The method as described in claim 12, wherein the high speed
spinning tube shrinkage tool further comprises a diminished
portion, the tapered portion being disposed between the guiding
portion and the diminished portion.
14. The method as described in claim 9, wherein the shrinkage tool
is a spinning stamping tube shrinkage tool, the shrinkage process
of the evaporator section comprises the step of controlling the
spinning stamping tube shrinkage tool to move towards the
evaporator section of the casing along a radial direction of the
casing so as to shrink the diameter of the evaporator section.
15. The method as described in claim 14, wherein the shrinkage
process of the evaporator section further comprises the step of
controlling the spinning stamping tube shrinkage tool to move
towards the evaporator section of the casing along a central
longitudinal axis of the heat pipe in order to obtain a
predetermine length for the evaporator section.
16. The method as described in claim 14, wherein the spinning
stamping tube shrinkage tool includes more than two sub-tools with
arc-shaped inner surfaces thereof distributed around an imaginary
circle which is coaxial with and surrounds the casing.
17. The method as described in claim 16, wherein each of the
sub-tools comprises diminished portion and a tapered portion
connecting with the diminished portion at an end thereof, a
diameter of the tapered portion being gradually increased from the
end towards an opposite end thereof.
18. The method as described in claim 17, wherein each of the
sub-tools further comprises an enlarged portion connecting with the
tapered portion at the opposite end thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to a heat pipe for
transfer or dissipation of heat from heat-generating components,
and more particularly to a heat pipe with variable grooved-wick
structure defined therein for increasing heat transfer capability
thereof.
[0003] 2. Description of Related Art
[0004] Nowadays, thermal modules are widely used in notebook
computers to dissipate heat generated by CPUs. The thermal module
includes a blower, a fin assembly, and a heat pipe. The heat pipe
has an evaporator section and a condenser section respectively
connected with a CPU and the fin assembly so as to transfer heat
generated by the CPU to the fin assembly. The fin assembly is
arranged at an air outlet of the blower to dissipate heat absorbed
from the condenser section of the heat pipe to the surrounding
environment.
[0005] In the thermal module, the evaporator section of the heat
pipe usually has a smaller area than the condenser section.
Accordingly, a contacting area between the evaporator section of
the heat pipe and the CPU is smaller than that between the
condenser section of the heat pipe and the fin assembly. Therefore,
the radial power density which the evaporator section of the heat
pipe undergoes is greater than that the condenser section of the
heat pipe needs to undergo.
[0006] In a conventional grooved heat pipe, grooves at the
evaporator section thereof have similar groove shapes to grooves at
the condenser section thereof. This means the evaporator section of
the conventional grooved heat pipe has the same radial power
density as the condenser section thereof, which limits the increase
of the heat transfer capability of the conventional grooved heat
pipe and further limits the increase of the heat dissipating
efficiency of the thermal module. Thus, it can be seen that
improvement of the radial power density of the evaporator section
of the heat pipe is key to improve the heat dissipation efficiency
of the thermal module.
SUMMARY OF THE INVENTION
[0007] The present invention relates to a heat pipe for removing
heat from heat-generating components and a method for manufacturing
the same. The heat pipe includes a casing, a plurality of grooves
defined in the casing, and working fluid contained in the casing.
The casing includes a first portion and a second portion having a
smaller diameter than the first portion. The grooves at the first
portion of the casing have smaller groove width than that of the
grooves at the second portion. The method includes the steps of:
providing a casing with a plurality of tiny grooves defined in an
inner wall thereof; shrinking a diameter of one portion of the
casing to function the portion as an evaporator section of the heat
pipe; vacuuming and placing a predetermined quantity of working
fluid in the casing; sealing the casing to obtain the heat
pipe.
[0008] 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
[0009] Many aspects of the present invention 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 invention. Moreover, in the drawings, like reference
numerals designate corresponding parts throughout the several
views:
[0010] FIG. 1 is a heat pipe in accordance with a preferred
embodiment of the present invention;
[0011] FIG. 2 is an enlarged transverse cross-sectional view of the
heat pipe of FIG. 1, taken along line II-II;
[0012] FIG. 3 is an enlarged transverse cross-sectional view of the
heat pipe of FIG. 1, taken along line III-III;
[0013] FIG. 4 is a flow chart showing a preferred method for
manufacturing the heat pipe of FIG. 1;
[0014] FIG. 5 is an explanatory view of a manufacturing method of
the heat pipe of FIG. 1;
[0015] FIG. 6 an enlarged transverse cross-sectional view of FIG.
5, taken along line VI-VI;
[0016] FIG. 7 is an explanatory view of another manufacturing
method of the heat pipe of FIG. 1;
[0017] FIG. 8 an enlarged transverse cross-sectional view of FIG.
7, taken along line VIII-VIII; and
[0018] FIG. 9 is a heat pipe in accordance with a second embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Referring to FIGS. 1 through 3, a heat pipe 10 in accordance
with a preferred embodiment of the present invention is shown. The
heat pipe 10 includes a casing 11, a plurality of tiny grooves 12,
13 axially defined in an inner wall of the casing 11, and a
predetermined quantity of bi-phase working fluid (not shown)
contained in the casing 11.
[0020] The casing 11 is a metallic hollow tube having a ring-like
transverse cross section and a uniform thickness T along a
longitudinal direction thereof. The casing 11 includes an
evaporator section 15 disposed at an end thereof, a condenser
section 14 disposed at the other end thereof, and an adiabatic
section 17 disposed between the evaporator and the condenser
sections 15, 14. A diameter of the evaporator section 15 is smaller
than that of the condenser section 14. A transition section 16 is
formed between the evaporator section 15 and the adiabatic section
17. A diameter of the transition section 16 is gradually decreased
from the adiabatic section 17 towards the evaporator section 15 so
that the transition section 16 has a taper-shaped
configuration.
[0021] The working medium is usually selected from a liquid which
has a low boiling point and is compatible with the casing 11, such
as water, methanol, or alcohol. Thus, the working medium can easily
evaporate to vapor when it receives heat in the evaporator section
15 and condense to liquid when it dissipates heat in the condenser
section 14.
[0022] The grooves are coextensive with a central longitudinal axis
of the casing 11. Grooves 12 at the evaporator section 15 of the
casing 11 have substantially similar heights H to the grooves 13 at
the condenser section 14 thereof. An apex angle A1 of each of the
grooves 12 at the evaporator section 15 is greater than an apex
angle A2 of each of the grooves 13 at the condenser section 14. A
top width W.sub.1 of each of the grooves 12 at the evaporator
section 15 is smaller than a top width W.sub.3 of each of the
grooves 13 at the condenser section 14, whilst a bottom width
W.sub.2 of each of the grooves 12 at the evaporator section 15 is
smaller than a bottom width W.sub.4 of each of the grooves 13 at
the condenser section 14. This means a middle width (groove width)
of each of the grooves 12 at the evaporator section 15 is smaller
than that of each of the grooves 13 at the condenser section
14.
[0023] Referring to FIG. 4, the heat pipe 10 is manufactured by
such steps: providing a metal casing 11 with a uniform diameter
along a longitudinal direction thereof; forming a plurality of
grooves in the inner wall of the casing 11; shrinking the diameter
of one portion of the casing 11 so as to allow the portion of the
casing 11 to function as the evaporator section 15 of the heat pipe
10; vacuuming and placing the predetermined quantity of the working
fluid into the casing 11; sealing the casing 11 to obtain the heat
pipe 10.
[0024] Referring to FIGS. 5 and 6, the evaporator section 15 of the
heat pipe 10 can be shrunk by high speed spinning tube shrinkage
treatment. A high speed spinning tube shrinkage tool 20 is a hollow
tube which includes a tapered portion 21 corresponding to the
transition section 16 of the heat pipe 10, and guiding and
diminished portions 22, 23 corresponding to the respective
condenser and evaporator sections 14, 15 of the heat pipe 10. The
guiding portion 22 connects with a front end of the transition
section 16, and the diminished portion 23 connects with a rear end
of the transition section 16. A diameter of an inner wall of the
guiding portion 22 of the high speed spinning tube shrinkage tool
20 is substantially equal to a diameter of an outer wall of the
condenser section 14. A diameter of an inner wall of the diminished
portion 23 of the high speed spinning tube shrinkage tool 20 is
substantially equal to a diameter of an outer wall of the
evaporator section 15 of the heat pipe 10. The tapered portion 21
enables to gradually diminish the diameter of the outer wall of the
evaporator section 15 so as to form the transition section 16. In
shrinkage of the original evaporator section of the casing 11, the
casing 11 of the heat pipe 10 is fixed to a work table 40 via two
fixing members 50; the high speed spinning tube shrinkage tool 20
is propelled to move from the original evaporator section towards
the condenser section 14 of the casing 11 along the central
longitudinal axis thereof to a predetermined length. In movement of
the tool 20, the guiding portion 22 guides the movement of the tool
20. Meanwhile, the tapered portion 21 compresses the outer wall of
the evaporator section 15 so as to shrink the diameter thereof and
thereby obtaining the needed heat pipe 10.
[0025] Referring to FIGS. 7 and 8, the evaporator section 15 of the
heat pipe 10 can also be shrunk using spinning stamping tube
shrinkage treatment. A spinning stamping tube shrinkage tool 30
includes three sub-tools 31 with arc-shaped inner surfaces 32
thereof evenly distributed around an imaginary circle 33 which is
coaxial with and surrounds the casing 11. The tool 30 includes a
tapered portion 34 corresponding to the transition section 16 of
the heat pipe 10, and enlarged and diminished portions 35, 36
corresponding to the respective condenser and evaporator sections
14, 15 of the heat pipe 10. A diameter of the tapered portion 34 is
gradually increased from the diminished portion 36 towards the
enlarged portion 35. A diameter of the diminished portion 36 of the
tool 30 at the imaginary circle 330 is greater than that of the
evaporator section 15 of the casing 11 before the shrinkage
operation, whilst a diameter of the diminished portion 36 of the
tool 30 is decreased to a predetermined value which is
substantially equal to the diameter of the evaporator section 15 of
the casing 11 after the shrinkage process. During shrinkage of the
evaporator section 15 of the casing 11, the casing 11 of the heat
pipe 10 is fixed to a work table 40 via a fixing member 50; the
three sub-tools 31 are rotated and at the same time are controlled
to move towards the evaporator section 15 of the casing 11 along a
radial direction of the casing 11 so as to shrink the diameter of
the evaporator section 15. Meanwhile, the sub-tools 31 may be
controlled to move towards the evaporator section 15 of the casing
11 along the central longitudinal axis of the heat pipe 10 in order
to obtain a predetermine length for the evaporator section 15. In
shrinkage of the evaporator section 15 of the casing 11, the
diameter of the imaginary circle 33 is gradually decreased to the
predetermined value.
[0026] In the present heat pipe 10, each of the grooves 12 at the
evaporator section 15 has smaller groove width and greater apex
angle than that of each of the grooves 13 at the condenser section
14. This increases the density of the grooves 12 at the evaporator
section 15 of the heat pipe 10. The radial power density the
evaporator section 15 of the heat pipe 10 can undergo is therefore
increased, and the thermal resistance of the evaporator section 15
of the heat pipe 10 is decreased. Thus, the heat transfer
capability of the heat pipe 10 is improved. In addition, the
capillary action generated by the grooves 12 at the evaporator
section 15 of the heat pipe 10 is increased, which increases the
heat transfer capabilities of the heat pipe 10. The heat transfer
capability of the heat pipe 10 is improved according to the
shrinkage of the evaporator section 15 of the heat pipe 10, which
simplifies the manufacturing of the heat pipe 10. In this way the
present heat pipe 10 is adapted for mass production.
[0027] In the present heat pipe 10, the evaporator section 15 and
the condenser section 14 are respectively disposed at two ends of
the casing 11. Alternatively, referring to FIG. 9, the casing 11a
may include two condenser sections 14a disposed at two ends
thereof, and an evaporator section 15a arranged at a middle portion
thereof. Two transition sections 16a are respectively disposed
between the evaporator section 15a and the condenser sections 14a.
Under this status, the evaporator section 15a of the casing 11a is
shrunk by spinning stamping tube shrinkage treatment. In order to
manufacture this kind of the heat pipe 10, the tool 30 may include
a diminished portion 36, two enlarged portions 35 disposed at two
sides of the diminished portion 36, and two tapered portions 34
respectively formed between the diminished portion 36 and the
enlarged portions 35. Furthermore, the heat pipe 10 can be bent to
L-shaped or U-shaped to satisfy different need for the heat pipe.
The heat pipe 10 can also be flattened so as to decrease the size
thereof for benefiting the heat pipe to be used in a size-limited
room such as an inner side of a laptop computer.
[0028] 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.
* * * * *