U.S. patent application number 11/134339 was filed with the patent office on 2006-11-23 for composite wick structure of heat pipe.
This patent application is currently assigned to FAFFE LIMITED. Invention is credited to Hul-Chun Hsu.
Application Number | 20060260786 11/134339 |
Document ID | / |
Family ID | 37447258 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260786 |
Kind Code |
A1 |
Hsu; Hul-Chun |
November 23, 2006 |
Composite wick structure of heat pipe
Abstract
A composite multi-layer wick structure includes a tubular member
with an internal sidewall, and a composite wick structure including
a multi-layer woven mesh and a sintered-powder layer. The
multi-layer woven mesh is curled to cover on and extend over the
internal sidewall. The sintered-powder layer is coated on a portion
of the multi-layer woven mesh and the internal sidewall to extend
along a longitudinal direction of the tubular member. By the strong
capillary force provided by the sintered-powder layer, the working
fluid at the liquid phase easily reflows back to the bottom of the
heat pipe, such that the heat transmission efficiency is greatly
enhanced.
Inventors: |
Hsu; Hul-Chun; (Taichung
City, TW) |
Correspondence
Address: |
HDSL
4331 STEVENS BATTLE LANE
FAIRFAX
VA
22033
US
|
Assignee: |
FAFFE LIMITED
|
Family ID: |
37447258 |
Appl. No.: |
11/134339 |
Filed: |
May 23, 2005 |
Current U.S.
Class: |
165/104.26 |
Current CPC
Class: |
F28D 15/046
20130101 |
Class at
Publication: |
165/104.26 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. A heat pipe comprising: a tubular member with an internal
sidewall; and a composite wick structure including a multi-layer
woven mesh curled to cover on and extend over the internal
sidewall, and a sintered-powder layer coated on a portion of the
multi-layer woven mesh and the internal sidewall to extend along a
longitudinal direction of the tubular member.
2. The heat pipe of claim 1, wherein the multi-layer woven mesh is
formed a cylindrical shape to securely attached to the tubular
member.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates in general to a composite wick
structure of a heat pipe, and more particularly, to a composite
wick structure fabricated from a multi-layer woven mesh and a
sintered powder layer.
[0002] Having the features of high heat transmission capability,
high-speed heat conductance, high thermal conductivity, light
weight, mobile-elements free, simple structure, the versatile
application, and low power for heat transmission, heat pipes have
been popularly applied in heat dissipation devices in the industry.
The conventional heat pipe includes a wick structure on an internal
sidewall of a tubular member. The wick structure typically includes
a woven mesh or sintered powder to aid in transmission of working
fluid.
[0003] However, the woven mesh or the sintered powder each has
advantages and drawbacks.
[0004] For example, the fine and dense structure of the
sintered-powder wick structure provides better capillary force for
reflow of the liquid-state working fluid. However, during
fabrication, an axial rod has to be inserted into the tubular
member to serve as a support member of the wick structure during
the sintering process, so as to avoid collapse of the powdered
which has not been sintered yet. Therefore, the thickness of the
sintered powder wick structure is thicker. Consequently, the
capillary thermal resistance is increased to be disadvantageous to
the heat transmission. Further, requirement of the axial rod
hinders the mass production of the heat pipe and causes fabrication
and quality issues of the heat pipe.
[0005] The woven mesh wick structure does not require the axial
rod, such that the problems of the sintered powder wick structure
do not encounter. Further, the woven mesh wick structure is more
easily to fabricate compared to the sintered-powder wick structure.
However, as the woven mesh is made by weaving metal wires, the
porosities are larger to provide a poor capillary effect. The
working fluid is less easily to reflow, and the thermal conduction
efficiency is affected.
[0006] Thus, there still is a need in the art to address the
aforementioned deficiencies and inadequacies.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides a composite wick structure of
a heat pipe. The composite structure adapts the advantages of both
the multi-layer woven-mesh and the sintered-powder wick structure,
such that the transmission capability of the wick structure is
maintained, and the heat conduction performance of the heat pipe is
improved, while the problems caused by the axial rod are
resolved.
[0008] A heat pipe provided by the present invention includes a
tubular member with an internal sidewall, and a composite wick
structure including a multi-layer woven mesh and a sintered-powder
layer. The multi-layer woven mesh is curled to cover on and extend
over the internal sidewall. The sintered-powder layer is coated on
a portion of the multi-layer woven mesh and the internal sidewall
to extend along a longitudinal direction of the tubular member. By
the strong capillary force provided by the sintered-powder layer,
the working fluid at the liquid phase easily reflows back to the
bottom of the heat pipe, such that the heat transmission efficiency
is greatly enhanced.
[0009] These and other objectives of the present invention will
become obvious to those of ordinary skill in the art after reading
the following detailed description of preferred embodiments.
[0010] It is to be understood that both the foregoing general
description and the following detailed description are exemplary,
and are intended to provide further explanation of the invention as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] These as well as other features of the present invention
will become more apparent upon reference to the drawings
therein:
[0012] FIG. 1 shows an exploded view of a multi-layer woven mesh
installing in a heat pipe;
[0013] FIG. 2 shows a cross sectional view of the heat pipe with
the multi-layer woven mesh;
[0014] FIG. 3 shows a cross sectional view of a composite wick
structure attached to heat pipe; and
[0015] FIG. 4 shows a cross sectional view along the longitudinal
direction of the heat pipe in operation.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers are used in the drawings and the description
to refer to the same or like parts.
[0017] FIGS. 1 and 2 illustrate an exploded view and a cross
sectional view of a heat pipe with a multi-layer woven mesh,
respectively. The heat pipe 1 comprises a tubular member 10 and the
multi-layer woven mesh 110.
[0018] The tubular member 10 is preferably in the form of a
cylindrical hollow tube having an internal sidewall 102 and two
open ends 100, 101. After filling a working fluid, a vacuum process
is performed so that the tubular member 10 can be closed and sealed
at both ends 100, 101 by a shrinking and sealing process.
[0019] Referring further to FIG. 3, a composite wick structure 11
of the present invention attached to the internal sidewall 102 of
the tubular member 10 includes the multi-layer woven mesh 110
extending all over the sidewall 102 and a sintered-powder layer 111
formed on at least a portion of the multi-layer woven mesh 110 and
the sidewall 102. The multi-layer woven mesh 110 is first curled to
be put into the tubular member 10 of the heat pipe 1. At this time,
the multi-layer woven mesh 110 has not formed a close
circumference. However, after a shrinking process, the
circumference of the multi-layer woven mesh 110 will be close to
form a cylindrical shape so that the multi-layer woven mesh 110 is
securely attached on the sidewall 102 of the heat pipe 1. The
sintered-powder layer 111 lays on a portion of the multi-layer
woven mesh 110 and the sidewall 102 to extend along a longitudinal
direction of the tubular member 10. As the sintered-powder layer
111 does not have to cover the whole area of the multi-layer woven
mesh 110, that is, the internal sidewall 102 of the tubular member
10, the traditional axial rod is not required. To form the
sintered-powder layer 111, the powder to be sintered is disposed
inside of the tubular member 10. The tubular member 10 is laid down
with the side at which sintered-powder layer 111 facing downwardly
for performing sintering.
[0020] By the above processes, a composite wick structure is
obtained.
[0021] Together referring to FIGS. 3 and 4, when a heat source
starts to generate heat, the working fluid in the heat pipe absorbs
the heat and is evaporated into a gas. The gas is then condensed
into a liquid absorbed by the wick structure 11 around the internal
sidewall 102 of the tubular member 10. Meanwhile, the
sintered-powder layer 111 has the better capillary effect to
instantly reflow the work fluid back to the location of the heat
source. On the other hand, some liquid working fluid at the woven
mesh 110 will also flow to the sintered-powder layer 111 along
circular direction because the flowing rate is faster at
sintered-powder layer 111. Thereby, the reflow speed of the working
fluid is greatly increased to enhance the heat transmission
efficiency.
[0022] Therefore, the composite wick 11 of the heat pipe 1 includes
both the advantages of the multi-layer woven mesh 110 and the
sintered-powder layer 111. The sintered-powder layer 111 provides
better capillary force for reflow of the liquid-state working
fluids without need of the axial rod anymore. Meanwhile, the
multi-layer woven mesh 110 is convenient for installation with
secure attachment to the sidewall 102 of the tubular member 10. The
multi-layer woven mesh 110 is not easy to collapse when a
high-temperature annealing process is performed so that the wick
structure 11 will have a reliable support.
[0023] This disclosure provides exemplary embodiments of wick
structure of a heat pipe. The scope of this disclosure is not
limited by these exemplary embodiments. Numerous variations,
whether explicitly provided for by the specification or implied by
the specification, such as variations in shape, structure,
dimension, type of material or manufacturing process may be
implemented by one of skill in the art in view of this
disclosure.
* * * * *