US20110088873A1

US20110088873A1 - Support structure for flat-plate heat pipe

Info

Publication number: US20110088873A1
Application number: US12/579,411
Authority: US
Inventors: Hsiuwei Yang
Original assignee: Asia Vital Components Co Ltd
Current assignee: Asia Vital Components Co Ltd
Priority date: 2009-10-15
Filing date: 2009-10-15
Publication date: 2011-04-21

Abstract

A support structure for flat-plate heat pipe, including a main body and a fitting body. The fitting body has at least one open side and a first side section connected with the open side. The first side section has a capillary structure formed on a periphery of the first side section. The first side section and the open side together define a space for fixedly fitting the main body therein. By means of the capillary structure of the first side section of the fitting body, the circulating rate of a working fluid flowing within the flat-plate heat pipe is increased to achieve better heat dissipation effect and better thermal uniformity.

Description

FIELD OF THE INVENTION

The present invention relates to a flat-plate heat pipe, and more particularly to an improved support structure for flat-plate heat pipe including a main body and a fitting body in which the main body is fitted. The fitting body has a first side formed with a capillary structure. By means of the capillary structure of the first side section of the fitting body, the circulating rate of a working fluid flowing within the flat-plate heat pipe is increased to achieve better heat dissipation effect and better thermal uniformity.

BACKGROUND OF THE INVENTION

Following the rapid progress of industrial technique, there is a trend in electronic products of miniaturized volume, light weight, low power consumption, high performance and high efficiency. Therefore, the working rate of the electronic products is enhanced and the number of electronic components per unit volume is increased. During continuous promotion of the performances of electronic products, the issue of heat dissipation has become more and more critical. Due to different performances of different electronic components, the thermal flux is non-uniformly distributed over the surfaces of the heat-generating electronic components. Therefore, the so-called “hot spot” will be formed on the surfaces due to local overheating. The reliability and lifetime of the electronic components are closely related to the operation temperature thereof, especially the peripheral components of compact notebook computers with limited volume. To solve the heat dissipation problem, various flat-plate heat pipes have been developed.
FIG. 1 shows a conventional flat-plate heat pipe composed of a first copper plate 10 and a second copper plate 11 corresponding to the first copper plate 10. The first copper plate 10 is connected with the second copper plate 11 to define a chamber 12 in which a working fluid (such as water or a liquid) is filled. The opposite surfaces of the first and second copper plates 10, 11 are formed with capillary structures 13 enclosing the chamber 12 as inner wall faces thereof. The capillary structures mainly serve to: 1. reduce thermal flux of the wall faces through liquid membrane effect; 2. increase boiling core and enlarge evaporation area; and 3. contact with the wall faces to hinder the vapor membrane from growing. Due to gravity and capillarity, the working fluid is distributed over the capillary structures 13 in the chamber 12, (that is, the capillary structures of the first and second copper plates 10, 11).
A back surface of the first copper plate 10 distal from the chamber 12 is in contact with an end face of a heat-generating component such as a CPU. In this case, the first copper plate 10 is the so-called evaporating end or heated end for conducting the heat generated by the heat-generating component to the second copper plate 11, which is the so-called condensing end to dissipate the heat. When the heat-generating component generates heat, the first copper plate 10 absorbs the heat and the working fluid flowing through the capillary structures 13 is heated to evaporate into vapor. Thereafter, the vapor quickly flows to the colder portion, (that is, the second copper plate 11). After the vapor reaches the second copper plate 11, the vapor will release the latent heat and change into liquid. The liquid then flows back to the first copper plate 10 due to the capillary attraction of the capillary structures 13 of the second copper plate 11 to complete a working cycle for dissipating the heat. However, there are some problems with the above structure. That is, the working fluid flowing through the capillary structures 13 of the first copper plate 10 can be hardly smoothly phase-changed. The problems are as follows: 1. The transformation rate of the working fluid between two phases is increased with the increment of the transferred heat. However, the capillary structures have low porosity and low infiltration rate so that the backflow resistance is increased. In this case, it is hard to provide sufficient working fluid to go back the evaporating end. As a result, the heated end of the heat pipe may dry out to lead to poor heating uniformity and poor heat dissipation effect. 2. The thermal flux will continuously rise to result in that the vapor pressure on the liquid level become greater than the pressure in the liquid. Under such circumstance, vapor bubbles will be produced in the capillary structures. The bubbles not only will hinder the working fluid from flowing back, but also will create a vapor membrane between the heat conduction face and the capillary structures of the heat pipe with very high thermal resistance. Due to the vapor membrane, the working fluid can hardly smoothly phase-change to carry the heat away from the evaporating end. As a result, the heat will continuously accumulate at the heated end. In this case, the heated end of the heat pipe will dry out to lead to poor heating uniformity and poor heat dissipation effect.
Please now refer to FIG. 2, which shows a heat pipe vapor chamber disclosed in Taiwanese Patent No. 443714. Multiple bosses 21 are disposed on the upper plate 20 of the vapor chamber 2. A capillary structure 23 is disposed on the lower plate 22 in abutment with the bosses 21 of the upper plate 20 for supporting the same. The capillary structure 23 serves to guide the condensed liquid to flow back. The bosses 21 are free from any capillary structure and are only used to provide support effect. Therefore, the liquid is simply guided by the capillary structure 23 of the lower plate 22 to flow back. As a result, the circulating rate of the fluid is low and the heat dissipation effect is poor.
According to the aforesaid, the prior art has the following defects:

1. The heat dissipation effect is poor.
2. The heating uniformity is poor.
3. The circulating rate of the fluid is poor.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide an improved support structure for flat-plate heat pipe including a main body and at least one fitting body. The fitting body has at least one open side and a first side section connected with the open side. The first side section has a capillary structure formed on a periphery of the first side section. The first side section and the open side together define a space for fixedly fitting the main body therein. By means of the capillary structure of the first side section of the fitting body, the circulating rate of a working fluid flowing within the flat-plate heat pipe is increased to achieve better heat dissipation effect and better thermal uniformity.
A further object of the present invention is to provide the above support structure for flat-plate heat pipe, which further includes a cover body connected with the main body. The cover body includes a first flat plate and a second flat plate in parallel to the first flat plate. The first and second flat plates define therebetween a chamber in which the main body is received and in which a working fluid is filled.
The main body has a top section, a second side section and a bottom section opposite to the top section. The top section and the bottom section respectively abut against the first and second flat plates. The fitting bodies are stacked and fitted around the main body. By means of the capillary structure of the first side section of the fitting body, the circulating rate of a working fluid flowing within the flat-plate heat pipe is increased to achieve better heat dissipation effect and better thermal uniformity.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein:

FIG. 1 is a sectional view of a conventional flat-plate heat pipe;

FIG. 2 is a sectional view of a conventional heat pipe vapor chamber;

FIG. 3 is a perspective view of the fitting body of a first embodiment of the present invention;

FIG. 4 is a perspective exploded view of the first embodiment of the present invention;

FIG. 5 is a sectional assembled view of the first embodiment of the present invention;

FIG. 6 is a perspective view of the fitting bodies of a second embodiment of the present invention, in which the fitting bodies are stacked;

FIG. 7 is a perspective exploded view of the second embodiment of the present invention; and

FIG. 8 is a sectional assembled view of the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 3, 4 and 5. According to a first embodiment, the support structure for flat-plate heat pipe of the present invention includes a main body 3 and a fitting body 4. The fitting body 4 has at least one open side 41 and a first side section 42 connected with the open side 41. The first side section 42 has a capillary structure 421 formed on a periphery of the first side section 42. The capillary structure 421 can be a porous structure in the form of metal spring, metal mesh or sintered metal powder. The capillary structure 421 has flow-guiding ability and provides multiple backflow channels. Accordingly, the capillary structure 421 serves to guide the fluid to quickly flow from the colder portion back to the heated portion so as to enhance fluid circulating rate and increase flow amount and prevent the fluid flowing within the heated portion from drying out. Alternatively, the periphery of the first side section 42 can be directly formed with channel-shaped or porous capillary structure 421 for enhancing attraction, evaporation, condensing and circulating effect.
The first side section 42 and the open side 41 together define a space 43 in communication with the open side 41. The main body 3 can be fixedly fitted into the space 43.
The fitting body 4 is a hollow body in the form of a cylindrical body, a rectangular block or a cubic body. In this embodiment, the fitting body 4 is, but not limited to, a hollow cylindrical body. in practice, the hollow fitting body has a configuration adapted to that of the main body. The hollow fitting body has a first end 411 and a second end 412 extending from the first end 411. The first and second ends 411, 412 define therebetween the open side 41.
Please now refer to FIGS. 3, 4, 5, 6 and 7. The main body 3 is made of a material with high thermal conductivity, such as copper, silver, aluminum or an alloy thereof. The main body 3 serves to quickly transfer (or conduct) heat from a high-temperature portion, that is, the heated portion to a low-temperature portion, that is, the colder portion to dissipate the heat so as to achieve good thermal uniformity and good heat dissipation effect. The main body 3 has a top section 31, a bottom section 32 and a second side section 33. The top section 31 and the bottom section 32 are respectively flush with the first end 411 and the second end 412 of the hollow fitting body. In other words, the main body 3 is fitted in the hollow fitting body with the top section 31 and the bottom section 32 of the main body 3 respectively flush with the first end 411 and the second end 412 of the hollow fitting body. In addition, inner side of the first side section 42 encloses and attaches to a circumference of the second side section 33.
Then, the main body 3 is connected to a cover body 5 in abutment therewith. The cover body 5 is made of a material with high thermal conductivity, such as copper, silver, aluminum or an alloy thereof. The cover body 5 includes a first flat plate 51 and a second flat plate 52 corresponding to the first flat plate 51. A back end face of the first flat plate 51 distal from the second flat plate 52 contacts with and attaches to a heat-generating component such as a CPU (not shown). The back end face of the first flat plate 51 that contacts with the heat-generating component is the above-mentioned heated portion (or referred to as an evaporating end). The second flat plate 52 is the above-mentioned colder portion (or referred to as a condensing end).
The first and second flat plates 51, 52 define therebetween a chamber 53 in which the hollow fitting body and the main body 3 fitted therein are received and in which a certain amount of working fluid is filled. In this embodiment, the working fluid is, but not limited to, water. In practice, the working fluid can be any kind of evaporable fluid such as pure water, inorganic compound, alcohol, ketone, liquid metal, coolant, organic compound or a mixture thereof. The main body 3 is disposed in the chamber 53 also for locating and supporting the first and second flat plates 51, 52. The hollow fitting body is fitted around the main body 3 to increase the contact area (or support area) between the first and second flat plates 51, 52. Therefore, the strength of the flat-plate heat pipe is enhanced and the assembling process is facilitated to lower cost.
The capillary structure 531 is disposed on inner surface of the chamber 53. That is, the capillary structure 531 is disposed on the opposite end faces (the inner surface of the chamber 53) of the first and second flat plates 51, 52. The working fluid is distributed over the capillary structure 531 of the first and second flat plates 51, 52.
When the heat-generating component generates heat, the working fluid in the capillary structure 531 of the first flat plate 51 (the evaporating end) absorbs the heat and phase-changes from liquid phase working fluid 55 into vapor phase working fluid 56. The vapor phase working fluid 56 will quickly flow across the chamber 53 to the second flat plate 52 (the condensing end). Also, part of the heat absorbed by the first flat plate 51 is quickly conducted through the main body 3 to the second flat plate 52 to dissipate the heat. After the vapor phase working fluid 56 reaches the second flat plate 52, the working fluid releases a great amount of latent heat to further phase-change into the liquid phase working fluid 55. At this time, the capillary structure 531 of the second flat plate 52 transfers the liquid phase working fluid 55 back to the first flat plate 51 by means of capillary attraction. In the meantime, the capillary structure 421 of the first side section 42 also provides capillary attraction to transfer the liquid phase working fluid 55 back to the first flat plate 51 in another path to enhance circulating rate of the working fluid. Accordingly, the heat is continuously carried away in the cycles to achieve better thermal uniformity and better heat dissipation effect.
FIGS. 6 to 8 show a second embodiment of the present invention, in which several fitting bodies 4 are stacked and fitted around the main body 3. To speak more specifically, the fitting bodies 4 are sequentially fitted around the main body 3 with the total of the heights of the fitting bodies 4 equal to the height of the main body 3. In this case, the fitting bodies 4 and the main body 3 fitted therein are arranged between the first and second flat plates 51, 52 in abutment therewith. In this embodiment, the number of the fitting bodies 4 is, but not limited to, three. Alternatively, there can be four, five, six or more fitting bodies in accordance with the height of the main body 3. That is, the number of the fitting bodies 4 is determined by the actual height of the main body 3.
According to the aforesaid, the support structure for flat-plate heat pipe of the present invention has the following advantages:

1. The present invention has better heat dissipation effect.
2. The present invention has better thermal uniformity.
3. The circulating rate of the working fluid is enhanced and the flow amount is increased.
4. The strength is enhanced and the support (contact) area is enlarged.

The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.

Claims

1. A support structure for flat-plate heat pipe, comprising:

a main body; and

a fitting body having at least one open side and a first side section connected with the open side, the first side section having a capillary structure formed on a periphery of the first side section, the first side section and the open side together defining a space for fixedly fitting the main body therein.

2. The support structure for flat-plate heat pipe as claimed in claim 1, wherein the capillary structure is a porous structure in the form of metal spring, metal mesh or sintered metal powder.

3. The support structure for flat-plate heat pipe as claimed in claim 1, wherein the periphery of the first side section is directly formed with channel-shaped or porous capillary structure.

4. The support structure for flat-plate heat pipe as claimed in claim 1, wherein the fitting body has the form of a cylindrical body, a rectangular block or a cubic body.

5. The support structure for flat-plate heat pipe as claimed in claim 1, wherein the main body is made of a material with high thermal conductivity.

6. The support structure for flat-plate heat pipe as claimed in claim 1, wherein the main body is connected to a cover body in abutment therewith, the cover body including a first flat plate and a second flat plate corresponding to the first flat plate, the first and second flat plates defining therebetween a chamber in which the main body is received and in which a working fluid is filled.