Patent Application
20100251547
1. Field of the Invention
The present invention relates to a heat transport device that transports heat by a phase change of a working fluid, and to a manufacturing method of the same, an electronic apparatus equipped with a heat transport device, and a caulking pin.
2. Description of the Related Art
In the past, a flat-plate heat pipe has been widely used as a device that cools a heat source such as a CPU (central processing unit). A flat-plate heat pipe cools a CPU and the like by using a phase change of a working fluid, and therefore contains a working fluid therein.
For example, Japanese Patent Application Laid-open No. 2007-315745 (hereinafter, referred to as Patent Document 1) discloses a flat-plate heat pipe, on an outer surface of which a refrigerant injection hole and an air outlet hole are formed. In the flat-plate heat pipe, a refrigerant such as water is injected through the refrigerant injection hole, and then a thermoplastic metal having a spherical body, such as solder, is placed at the refrigerant injection hole and the air outlet hole.
Subsequently, the spherical thermoplastic metal is pressurized and deformed at a low temperature, thereby temporarily sealing the refrigerant injection hole and the air outlet hole. After that, the thermoplastic metal is pressurized and deformed at a high temperature, thereby sealing the refrigerant injection hole and the air outlet hole (see, for example, paragraph 0176 of Patent Document 1).
In the heat pipe disclosed in Patent Document 1, the thermoplastic metal is used as a sealing member for the hole, which has a problem of low reliability of airtightness in the heat pipe. For example, after the heat pipe is formed, in a reflow process for mounting the heat pipe on another member, heat may be applied to the heat pipe in some cases. In this case, the thermoplastic metal as the sealing member may be molten or softened, which may cause a clearance in the hole. Therefore, there is a problem in that the airtightness in the heat pipe is difficult to be maintained.
In view of the above-mentioned circumstances, it is desirable to provide a manufacturing method of a heat transport device that enables to improve airtightness of the inside of a heat transport device, and provide a heat transport device, an electronic apparatus equipped with the same, and a caulking pin.
According to an embodiment of the present invention, there is provided a method of manufacturing a heat transport device including the following steps.
A working fluid that transports heat by a phase change is injected into a casing through an injection opening of the casing under reduced pressure.
An injection path is sealed by caulking under the reduced pressure. The injection path is provided in the casing into which the working fluid is injected and causing the injection opening and an action area in which the phase change of the working fluid occurs to communicate with each other.
A peripheral area of the injection opening of the casing is contacted with an inner surface of the injection path by caulking the peripheral area. The peripheral area includes the injection opening.
The injection opening is sealed by welding a part of the casing contacted.
In this embodiment, the injection path is sealed by caulking under the reduced pressure, that is, the injection path is temporarily sealed before the welding process, with the result that the airtightness of the action area in the casing can be secured before the welding process. Because the contact process and the welding process of the peripheral area of the injection opening are performed in the state where the action area of the airtightness is secured, it is possible to improve the airtightness of the action area in the casing of the product.
The caulking in the sealing of the injection path is linear crushing of the casing. The casing is linearly crushed, with the result that the pressure for the crushing can be larger as compared to a case where the casing is crushed with a plane. Therefore, the airtightness of the injection path after the sealing can be reliably secured. In addition, even in a case where the injection path is short, that is, a distance from the injection opening to the action area is short, the linear sealing can be performed.
The meaning of the linear sealing includes a sealing in a straight line, a curved line, or a line in combination with the straight line and the curved line.
The caulking in the sealing of the injection path is crushing of an area that surrounds the injection opening of the casing. By the crushing process, an inner area in the injection path, which is communicated with the injection opening, is separated from an outer area in the injection path, which is communicated with the injection opening. Thus, at the time of welding, it is possible to suppress an influence of heat given to the outer area in the injection path, which is communicated with the injection opening.
The caulking in the sealing of the injection path may be performed on an area on the injection path outside an area that surrounds the injection opening. That is, because the caulked area is distanced from the injection opening from the injection opening, it is possible to suppress an influence of heat given to the caulked area of the casing at the time of welding.
The contacting may be performed under an atmospheric pressure after the sealing of the injection path. Because the contacting process can be performed under the atmospheric pressure, it becomes easy to manufacture a heat transport device, and it is possible to cut a manufacturing cost.
The contacting is performed simultaneously with the sealing of the injection path. As a result, the number of manufacturing processes can be reduced, and thus time required for the manufacturing can be reduced.
The sealing of the injection path may be crushing of the casing with a blade. By using the blade, the pressure for the crushing can be increased as compared to a case where a member having a flat end surface for crushing the casing is used, with the result that the airtightness is improved.
The blade may be annularly formed in a direction in which the casing is crushed. For example, in a case where an inner diameter of the blade is larger than the width (width in a direction perpendicular to a direction in which the working fluid injected from the injection opening flows) of the injection path, the injection path can be crushed with two lines at the same time, for example. As a result, the airtightness can be realized with higher accuracy at the time of the temporary sealing.
The sealing of the injection path may be crushing of the area that surrounds the injection opening of the casing by using a caulking pin with the injection opening being surrounded with an annular blade of the caulking pin, the caulking pin having the annular blade and a concave portion.
The annular blade is formed in a direction in which the casing is crushed.
The concave portion is formed from the blade and having an inner surface formed vertically from an opening surface of the concave portion that is surrounded by the blade.
Because the inner surface of the concave portion is formed vertically from the opening surface (end surface of the caulking pin) of the concave portion, it is possible to minimize the stress applied to a part of the casing in the concave portion of the caulking pin at the time when the casing is crushed with the caulking pin. Therefore, deformation of the casing in the concave portion is suppressed, and the welding process subsequent thereto can be desirably performed.
Alternatively, the sealing of the injection path may be crushing of the area that surrounds the injection opening of the casing by using a caulking pin with the injection opening being surrounded with an annular blade of the caulking pin, the caulking pin having the annular blade and a concave portion.
The annular blade is formed in a direction in which the casing is crushed.
The concave portion has one of a conical shape and a pyramidal shape tapered with increasing distance from an opening surface of the concave portion that is surrounded by the blade.
The deformation of the part of the casing in the concave portion as described above is prevented depending on the inner diameter of the annular blade, the size of the injection opening, or the material of the casing. Therefore, the concave portion may be formed in the conical or pyramidal shape as in this embodiment.
The conical or pyramidal shape includes a conical and three-or-more-sided pyramidal shape.
The caulking pin may have a convex portion formed in the concave portion toward the opening surface of the concave portion that is surrounded by the blade. As described above, by getting the blade of the caulking pin into the casing, the convex portion functions so as to suppress the deformation of the part of the casing in the concave portion. As a result, the welding process subsequent thereto can be desirably performed.
According to another embodiment of the present invention, there is provided a heat transport device including a working fluid and a casing.
The working fluid transports heat by a phase change.
The casing includes an injection opening for the working fluid, an action area, and an injection path.
In the action area, the phase change of the working fluid occurs.
The injection path causes the injection opening and the action area to communicate with each other and is sealed by caulking.
In the casing, the peripheral area of the injection opening of the casing is formed to be crushed, the peripheral area including the injection opening. The injection opening is sealed by welding the peripheral area of the injection opening with an inner surface of the injection path.
According to another embodiment of the present invention, there is provided an electronic apparatus equipped with the heat transport device described above.
According to another embodiment of the present invention, there is provided a caulking pin of a heat transport device including a casing. The caulking pin crushes the casing. The casing has an injection opening for a working fluid, an action area in which a phase change of the working fluid occurs, and an injection path that causes the injection opening and the action area to communicate with each other. The caulking pin includes an annular blade and a concave portion.
The annular blade is formed in a direction in which the casing is crushed.
The concave portion is formed from the blade and has an inner surface formed from an opening surface of the concave portion that is surrounded by the blade.
According to another embodiment of the present invention, there is provided a heat transport device including a working fluid between a first member and a second member. The heat transport device includes a contact portion and a welding portion.
On the contact portion, the first member and the second member are contacted annularly.
On the welding portion, the first member and the second member are welded inside the contact portion.
As described above, according to the embodiments of the present invention, in the temporary sealing process in the manufacturing process, the airtightness in the casing of the heat transport device can be improved. Further, the airtightness in the casing of the heat transport device as a completed product can also be improved.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of best mode embodiments thereof, as illustrated in the accompanying drawings.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The heat transport device 100 includes a flat plate 1, a capillary member 3, a vapor flow path (not shown), and a dish-like container plate 2 having a concave portion 2a in which the capillary member 3 and the vapor flow path are contained. The flat plate 1, the capillary member 3, and the container plate 2 are formed into a rectangular shape, for example. The flat plate 1 and the container plate 2 constitute a casing 12 of the heat transport device 100.
In the casing 12, a working fluid (not shown) that transports heat by a phase change is sealed. The capillary member 3 causes a capillary force to act on a liquid-phase working fluid, thereby holding the liquid-phase working fluid. The capillary member 3 and the vapor flow path (not shown) are provided inside the casing 12, that is, provided so as to be approximately filled in the concave portion 2a of the container plate 2. The area inside the casing 12, that is, an area in which the capillary member 3 and the vapor flow path (not shown) are disposed functions as an action area 8 in which a phase change of the working fluid is caused.
Examples of a material of the flat plate 1 and the container plate 2 include metals such as copper, aluminum, and stainless. Further, examples of a material of the working fluid include ethanol, methanol, acetone, isopropyl alcohol, hydrochlorofluorocarbon, ammonia, and the like.
Typically, the capillary member 3 has a mesh structure with a metal thin wire. In addition to the mesh structure, a structure in which a plurality of wires are bulked may be used. Alternatively, a plurality of members each having the mesh structure may be layered to constitute the capillary member 3.
The vapor flow path (not shown) may be included in the capillary member 3. For example, a cellular mesh, a space between the meshes, or a space between a bottom of the convex portion 2a and the capillary member 3 may be formed as the vapor flow path.
As a material of the flat plate 1, the container plate 2, and the capillary member 3, a material having high heat conductivity, such as a carbon nanomaterial may be used in addition to the metal described above.
(Action of Heat Transport Device)
A description will be given on actions of the heat transport device 100 structured as described above.
As shown in
The heat transport device 100 receives heat of the heat source 9 from the position at which the heat source 9 is disposed, and the working fluid in the liquid phase evaporates, getting into a gas phase. The gas-phase working fluid moves in the casing 12 to a side opposite, in the longitudinal direction, to the side where the heat source 9 is disposed, thereby radiating heat and condensing. The working fluid that has condensed on the side opposite to the side of the heat source 9 is moved in the casing 12 to a heat absorption portion by a capillary force of the capillary member 3. Then, the working fluid receives heat from the heat source 9 and evaporates again. This cycle is repeated, thereby cooling the heat source 9.
(Method of Manufacturing Heat Transport Device)
Next, a description will be given on a method of manufacturing the heat transport device 100.
As shown in
The injection path 2c may be formed by, for example, an end-milling process, a laser process, a press process, or a miniaturization process such as a photolithography and a half etching in a semiconductor manufacturing. When the press process is used, a burr is not formed. When the laser process or the end-milling process is used, a mold is unnecessary, and a groove in any form can be formed.
As shown in
In Step S102, air in the casing 12 is exhausted. The exhaust process and processes of Steps S103 and S104 subsequent thereto are performed in a vacuum chamber (not shown), for example. The vacuum chamber only has to be evacuated to a predetermined degree of vacuum (degree of depressurization), to exhaust air in the casing 12. Instead of the form in which the entire casing 12 is contained in the vacuum chamber, a space around the injection opening 1a may be locally depressurized by using a dedicated jig.
In Step S103, the working fluid is injected into the casing 12 exhausted. For example, in the vacuum chamber, a container, in which a liquid working fluid is retained, is disposed, and the casing 12 is immersed in the working fluid in the container, thereby injecting the working fluid into the action area 8 through the injection opening 1a by a predetermined amount. Instead, an injection tool (not shown) may be used for injecting the working fluid into the casing 12.
In Step S104, the injection path 2c of the casing 12 is sealed by caulking or swaging (temporary sealing).
In
The size is not limited to the above. As shown in
When the blade 21 has the circular form, and the circular temporary sealing groove 1b′ is formed, the injection opening 1a can be separated from the action area 8. Therefore, the diameter d2 of the temporary sealing groove 1b′ may be set to be smaller than the width L as described above.
In addition, when the casing 12 is crushed in an annular form, it becomes unnecessary to crush the entire casing 12 in the direction of the width L in the case where the width L of the injection path 2c is relatively large, particularly in the form shown in
Here, as shown in
With reference to
The peripheral area 1d of the injection opening 1a of the casing 12, which includes the injection opening 1a, refers to an area of the casing 12 within a range that the contacted portion can be welded by caulking with the caulking pin 20. The area is a larger area than the size of the injection opening 1a in the cross section as shown in
In Step S106, as shown in
As described above, in this embodiment, the injection path 2c is temporarily sealed before the welding process in a vacuum, with the result that the airtightness of the action area 8 in the casing 12 can be secured before the welding process. In this way, the processes (Steps 105 and 106) of contacting and welding of the peripheral area 1d of the injection opening 1a, which includes the injection opening 1a, are performed while securing the airtightness of the action area 8. As a result, the airtightness of the action area 8 in the casing 12 of the product can be improved.
Further, the manufacturing method according to this embodiment provides the following advantage. Although a vacuum welding with a laser generally requires a process time and cost of equipment for the vacuum welding, the welding with the laser can be performed under the atmospheric pressure in this embodiment. Thus, there is an advantage in that the process time can be saved, and the cost of the equipment for the vacuum welding can be eliminated. In addition, the process of Step S105 can also be performed under the atmospheric pressure, so the same advantage as above can be provided.
In this embodiment, the caulking pin 20 having the annular blade 21 crushes the casing 12. That is, the temporary sealing groove 1b as a circular-lined groove is formed in the casing 12. In this way, because the casing 12 is linearly crushed with the blade 21, the pressure of the crushing can be larger as compared to a case where the casing 12 is crushed with a plane surface. As a result, the airtightness of the injection path 2c after the sealing can be reliably secured.
In addition, because the caulking pin 20 having the annular blade 21 crushes the casing 12, an area 2d in the injection path 2c, which is communicated with the injection opening 1a is separated from an outer area 2e (other than the area 2d) in the injection path 2c, which is communicated with the injection opening 1a. Thus, it is possible to suppress an influence of heat given to the outer area 2e in the injection path 2c, which is communicated with the injection opening 1a, at the time of performing the welding with the laser.
An injection path 33 of a casing 32 of the heat transport device 200 has an L-letter shape and is connected to an edge portion 8a of the action area 8, thereby allowing the injection path 33 and the action area 8 to communicate with each other. Like the heat transport device 100 according to the first embodiment, the heat transport device 200 includes a flat plate 31 having the injection opening 31a, a container plate having the L-letter shaped injection path 33, and the capillary member 3 (see,
In Step S104, the mode in which the peripheral area of the injection opening 1a of the casing 12 is shown. On the other hand, in Step S204, a temporary sealing groove 31b as a crushed area (caulked area) corresponds to an area in the casing 32 other than an area surrounding the injection opening 31a on the injection path 33. That is, the temporary sealing groove 31b is distanced from the injection opening 31a, for example, provided at a position closer not to the injection opening 31a but to the action area 8. Therefore, it is possible to suppress an influence of heat given to the temporary sealing groove 31b of the casing 32 at the time of the welding with the laser. Also in Step S204, the caulking pin 20 shown in
The heat influence given to the caulked area of the casing refers to an influence of impairing the airtightness due to deformation of the caulked area depending on a welded position with the laser or a heat temperature, for example.
Further, in Step S204, the use of the caulking pin 20 having the annular blade 21 provides the following advantage. For example, in a case where the inner diameter d1 of the blade 21 is larger than the width L of the injection path 33, the injection path 33 can be crushed with two lines at the same time as shown in
In this embodiment, in Step S205, a peripheral area of the injection opening 31a of the casing 32, which includes the injection opening 31a, is crushed and brought into contact with the inner surface of the injection path 33, as in Step S105. In this case, the peripheral area of the injection opening 31a of the casing 32, which includes the injection opening 31a, may be set so that the peripheral area is larger than the injection opening 31a, and the action area 8 is not crushed in
In the casing 32 shown in
The front surface of the flame body 27 is a bonding surface 27a, which is bonded to the first flat plate 26 by the diffusion bonding. The back surface of the flame body 27 opposite to the front surface is a bonding surface 27b, which is bonded to the second flat plate 28 by the diffusion bonding. In a rectangular through hole 27c of the flame body 27, the capillary member 3 and a vapor flow path (not shown) are provided. The first flat plate 26, the flame body 27, and the second flat plate 28 constitute a casing 25.
At an end portion of the second flat plate 28, an injection opening 28a is formed, and an injection path 28b as a groove communicated with the injection opening 28a is formed. The injection path 28b is formed in an L-letter shape in a plan view. The injection path 28b is communicated with the action area 8 (see,
The injection path 28b may be formed by the laser process, the press process, or the end-milling process as described above. In the case of the press process, the surface (surface of the casing) of the second flat plate 28 is protruded.
The heat transport device 300 as described above can be manufactured by the method similar to the processes shown in
In this case, the inner surface of the injection path 28b corresponds to the bonding surface 27b of the flame body 27. In Step S206, the contacted areas are bonded by the laser bonding, thereby sealing the injection opening 28a.
In
In a case where the injection path 37a is formed on the flame body 37 by, for example, the press process, a surface of the flame body 37 opposite to the side on which the injection path 37a is formed is protruded. In this case, it is difficult to bond the flame body 37 and the second flat plate 38 with each other. Accordingly, in this embodiment, the injection path 28b has to be formed by the laser process or the end-milling process.
(Other Modes of Caulking Pin)
The blade 41 of the caulking pin 40 surrounds and crushes the injection opening 1a of the casing 12, thereby temporarily sealing the injection path 2c. Because the concave portion 42 of the caulking pin 40 has the conical shape, an area in the vicinity of the injection opening 1a of the casing 12 is protruded like a part of a sphere as shown in
In the caulking pin 50 shown in
The leakage refers to a leakage of air into the casing 12 (action area 8) from the outside of the casing 12 via the injection opening 1a and the injection path 2c. The result shows that caulking pins of Nos. 4, 6, 9, and 14 caused no leakage, and were judged to be effective. The caulking pin of No. 4 substantially corresponds to the caulking pin 40 shown in
(Electronic Apparatus)
Next, a description will be given on an electronic apparatus equipped with a heat transport device. Herein, a laptop PC is used as an example of the electronic apparatus.
In a casing of the main body 70, a CPU 90 and a heat transport device 100 are provided. The heat transport device 100 is thermally contacted with the CPU 90.
The electronic apparatus is not limited to the PC 500. Examples of the electronic apparatus include a PDA (personal digital assistant), an electronic dictionary, a camera, a display apparatus, audiovisual equipment, a projector, a printer, a fax machine, a cellular phone, a game machine, a car navigation system, a robot apparatus, and other electronic apparatuses.
The present invention is not limited to the above embodiments, and various other embodiments may be conceived.
The blade of the caulking pin has the circular shape, but may have an oval shape, a triangular or polygonal shape, or a combination thereof. That is, the annular shape may be any shape, as long as the groove is formed completely around the injection opening of the casing.
In
The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-092782 filed in the Japan Patent Office on Apr. 7, 2009, the entire content of which is hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-092782 | Apr 2009 | JP | national |
