U.S. patent application number 11/309312 was filed with the patent office on 2007-10-18 for heat pipe.
This patent application is currently assigned to FOXCONN TECHNOLOGY CO., LTD.. Invention is credited to Qian-Hua He, CHUEN-SHU HOU, TAY-JIAN LIU, CHAO-NIEN TUNG, Ji-Feng Wang.
Application Number | 20070240851 11/309312 |
Document ID | / |
Family ID | 38603727 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070240851 |
Kind Code |
A1 |
LIU; TAY-JIAN ; et
al. |
October 18, 2007 |
HEAT PIPE
Abstract
A heat pipe includes a hollow metal casing (10). The casing has
an evaporating section (120) and a condensing section (160) at
respective opposite ends thereof, and an adiabatic section (140)
located between the evaporating section and the condensing section.
A capillary wick structure (12) is arranged at an inner surface of
the hollow metal casing. A sealed heat reservoir (20) is mounted on
the evaporating section of the heat pipe to increase heat absorbing
area of the heat pipe. The heat reservoir has working fluid and a
capillary wick structure (22) therein. Heat generated by a heat
source is first absorbed by the heat reservoir and then transferred
to the evaporating section of the metal casing.
Inventors: |
LIU; TAY-JIAN; (Tu-Cheng,
TW) ; TUNG; CHAO-NIEN; (Tu-Cheng, TW) ; HOU;
CHUEN-SHU; (Tu-Cheng, TW) ; Wang; Ji-Feng;
(Shenzhen, CN) ; He; Qian-Hua; (Shenzhen,
CN) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. CHENG-JU CHIANG JEFFREY T. KNAPP
458 E. LAMBERT ROAD
FULLERTON
CA
92835
US
|
Assignee: |
FOXCONN TECHNOLOGY CO.,
LTD.
Tu-Cheng
TW
|
Family ID: |
38603727 |
Appl. No.: |
11/309312 |
Filed: |
July 25, 2006 |
Current U.S.
Class: |
165/104.14 ;
165/104.33 |
Current CPC
Class: |
F28D 15/0275
20130101 |
Class at
Publication: |
165/104.14 ;
165/104.33 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2006 |
CN |
200610060306.1 |
Claims
1. A heat pipe comprising: a hollow metal casing having an
evaporating section for receiving heat and a condensing section for
releasing the heat, and an adiabatic section located between the
evaporating section and the condensing section; a first working
fluid contained in the metal casing; a first capillary wick
structure arranged at an inner surface of the hollow metal casing;
and a sealed heat reservoir mounted on the evaporating section of
the heat pipe for absorbing heat generated by a heat source and
transferring the heat generated by the heat source to the
evaporating section of the metal casing, wherein the heat reservoir
has a second working fluid and a second capillary wick structure
contained therein.
2. The heat pipe of claim 1, wherein the evaporating section of the
heat pipe is inserted into the heat reservoir and is
interferentially connected with the heat reservoir.
3. The heat pipe of claim 1, wherein the second capillary wick
structure is arranged at an inner surface of the heat reservoir and
an outer surface of the evaporating section.
4. The heat pipe of claim 1, wherein the heat reservoir comprises
an outer wall and a pair of opposite lateral sides connects with
two opposite ends of the outer wall.
5. The heat pipe of claim 4, wherein an inner wall is formed in the
heat reservoir, and the evaporating section of the heat pipe is
inserted into the heat reservoir and engaged with the inner wall of
the heat reservoir.
6. The heat pipe of claim 1, wherein the heat pipe and the heat
reservoir respectively have a circular cross section.
7. The heat pipe of claim 1, wherein the heat pipe has a circular
cross section and the heat reservoir has a quadrilateral cross
section.
8. The heat pipe of claim 1, wherein the heat pipe has a
quadrilateral cross section and the heat reservoir has a circular
cross section.
9. The heat pipe of claim 1, wherein the heat pipe has a circular
cross section and the heat reservoir has a triangular cross
section.
10. The heat pipe of claim 1, wherein the heat pipe and the heat
reservoir each have a quadrilateral cross section.
11. The heat pipe of claim 1, wherein the heat reservoir surrounds
the evaporating section of the metal casing.
12. The heat pipe of claim 1, wherein the evaporating section of
the metal casing is inserted into the heat reservoir and soldered
to the heat reservoir.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a heat pipe as
heat transfer/dissipating device, and more particularly to a heat
pipe which has a heat reservoir for quickly absorbing heat received
from an electronic component such as a Central Processing Unit
(CPU) to increase the maximum heat transfer capacity and reduce the
temperature differential across the length of the heat pipe.
DESCRIPTION OF RELATED ART
[0002] It is well known that a heat pipe is generally a
vacuum-sealed pipe. A porous wick structure is provided on an inner
face of the pipe, and where 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, namely, an evaporating section, a
condensing section and an adiabatic section between the evaporating
section and the condensing section.
[0003] 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.
[0004] However, during the phase change of the working media, the
resultant vapor and the condensed liquid flows along two opposite
directions, which reduces the speed of the condensed liquid in
returning back to the evaporating section and therefore limits the
maximum heat transfer capacity (Qmax) of the heat pipe. As a
result, the heat pipe often suffers dry-out problem at the
evaporating section as the condensed liquid cannot be timely sent
back to the evaporating section of the heat pipe. Furthermore, the
heat pipe has a high ratio of length to radius so that the heat is
dissipated during transmission of the vapor and a part of the vapor
prematurely changes into condensed liquid before reaching the
condensing section. The prematurely condensed liquid is mixed in
the vapor to block transfer of the vapor. Thus, thermal resistance
of the heat pipe is accordingly increased and the maximum heat
transfer capacity of the heat pipe is reduced. In addition, the
heat pipe has a uniform thickness of the wick structure and a
uniform vapor channel for passage of the vapor so that a speed of
the vapor transferring from the evaporating section to the
condensing section is reduced, whereby the temperature difference
(.DELTA.T) between the evaporating section and the condensing
section is increased.
[0005] A conventional method for increasing the maximum heat
transfer capacity of the heat pipe is increasing the total
thickness of the wick structure of the heat pipe to increase the
quantity of the working media contained in the wick structure.
However, by this method, the response time of the heat pipe for the
liquid at the evaporating section to become the liquid is increased
and the temperature difference between the evaporating section and
the condensing section is increased accordingly.
[0006] A conventional method for reducing the temperature
difference between the evaporating section and the condensing
section is reducing the total thickness of the wick structure of
the heat pipe to reduce the quantity of the working media contained
in the wick structure. However, by this method, the maximum heat
transfer capacity of the heat pipe is reduced accordingly.
[0007] Therefore, it is desirable to provide a heat pipe which can
simultaneously increase the maximum heat transfer capacity and
reduce the temperature difference of the heat pipe.
SUMMARY OF THE INVENTION
[0008] The present invention relates to a heat pipe. A heat pipe
includes a hollow metal casing. The casing has an evaporating
section and a condensing section at respective opposite ends
thereof, and an adiabatic section located between the evaporating
section and the condensing section. A capillary wick structure is
arranged at an inner surface of the hollow metal casing. A sealed
heat reservoir is mounted on the evaporating section of the heat
pipe to increase heat absorbing area of the heat pipe. The heat
pipe is so configured to simultaneously reduce heat resistance and
enhance maximum heat transfer capacity of the heat pipe.
[0009] 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
[0010] 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.
[0011] FIG. 1 is a longitudinally cross-sectional view of a heat
pipe in accordance with a first embodiment of the present
invention;
[0012] FIG. 2 is a transversely cross-sectional view taken along
lines II-II of FIG. 1;
[0013] FIG. 3 is a transversely cross-sectional view of a heat pipe
in accordance with a second embodiment of the present
invention;
[0014] FIG. 4 is a transversely cross-sectional view of a heat pipe
in accordance with a third embodiment of the present invention;
[0015] FIG. 5 is a transversely cross-sectional view of a heat pipe
in accordance with a fourth embodiment of the present invention;
and
[0016] FIG. 6 is a transversely cross-sectional view of a heat pipe
in accordance with a fifth embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] FIGS. 1 and 2 show a heat pipe in accordance with one
embodiment of the present invention. The heat pipe has a
cylindrical configuration and includes a metal casing 10 made of
highly thermally conductive materials such as copper or copper
alloys, a first working fluid (not shown) contained in the casing
10 and a first capillary wick structure 12 arranged in an inner
surface of the casing 10. The casing 10 includes an evaporating
section 120 at one end, a condensing section 160 at the other end
and an adiabatic section 140 arranged between the evaporating
section 120 and the condensing section 160. A sealed heat reservoir
20 is mounted on the evaporating section 120. A vapor channel 14 is
defined along an axial direction of the heat pipe and is located at
a center of the casing 10. The vapor channel 14 is surrounded by an
inner surface of the first capillary wick structure 12 so as to
guide vapor to flow therein.
[0018] The heat reservoir 20 has a hollow cylindrical configuration
and made of highly thermally conductive materials such as aluminum
or copper or copper alloys. The heat reservoir 20 has a bigger
radius than that of the heat pipe. The evaporating section 120 of
the heat pipe extends through the heat reservoir 20, thereby to
position the heat reservoir 20 thereon. The heat reservoir 20
comprises an outer wall 211 and a pair of lateral sides 221
connecting with two opposite ends of the outer wall 211 to form a
sealed chamber. A second capillary wick structure 22 is formed at
an inner surface of the heat reservoir 20 and an outer surface of
the evaporating section 120. A second working fluid (not shown) is
contained in the heat reservoir 20. A vapor channel 24 is defined
along an axial direction of the heat reservoir 20 and is located at
a center of the heat reservoir 20 to guide vapor to flow therein.
The heat reservoir 20 is vacuum-exhausted to make the second
working fluid easy to evaporate.
[0019] In use, the heat reservoir 20 mounted on the evaporating
section 120 of the heat pipe first absorbs heat from heat resource;
the heat is transferred to the second working fluid contained in
the heat reservoir 20 whereby the second working fluid evaporates
into vapor. The vapor condenses and releases the heat. Then the
heat is transferred to the first working fluid contained in the
evaporating section 120 so that the first working fluid quickly
evaporates into vapor. The generated vapor moves towards and
carries the heat simultaneously to the condensing section 160 where
the vapor is condensed into liquid after releasing the heat into
ambient environment. The heat reservoir 20 has a so large heat
absorbing area that the heat from the heat resource can be quickly
absorbed by the heat reservoir 20. The absorbed heat is then
quickly transferred to the evaporating section 120 and released at
the condensing section 160, thereby to reduce the heat resistance
of the heat pipe and enhance the maximum heat transfer capacity of
the heat pipe.
[0020] Alternatively, a cylinder inner wall (not shown) is formed
in the heat reservoir 20. The inner wall interconnects the two
opposite lateral sides 221. The evaporating section 120 of the heat
pipe is inserted into the heat reservoir 20 and is interferentially
engaged with the inner wall of the heat reservoir 20, whereby the
heat reservoir 20 is positioned on evaporating section 120 of the
heat pipe. Alternatively, the heat reservoir 20 is positioned on
the evaporating section 120 of the heat pipe by solder means or
glue means.
[0021] FIG. 3 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, a heat reservoir 20a replaces the heat reservoir 20 of the
previous first embodiment. In the second embodiment, the heat
reservoir 20a has a square cross section.
[0022] FIG. 4 illustrates a heat pipe according to a third
embodiment of the present invention. In this embodiment, the heat
pipe has a similar structure to the heat pipe of the previous first
embodiment. However, a casing 10b of the heat pipe replaces the
casing 10 of the previous first embodiment. In the third
embodiment, the casing 10b has a square cross section.
[0023] FIG. 5 illustrates a heat pipe according to a fourth
embodiment of the present invention. In this embodiment, the heat
pipe has a similar structure to the heat pipe of the previous first
embodiment. However, a heat reservoir 20c replaces the heat
reservoir 20 of the previous first embodiment. In the fourth
embodiment, the heat reservoir 20a has a triangular cross
section.
[0024] FIG. 6 illustrates a heat pipe according to a fifth
embodiment of the present invention. In this embodiment, the heat
pipe has a similar structure to the heat pipe of the previous third
embodiment. However, a heat reservoir 20d replaces the heat
reservoir 20 of the previous third embodiment. In the fifth
embodiment, the heat reservoir 20a has a square cross section.
[0025] 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.
* * * * *