JP4516676B2 - Flat plate heat pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pipe that transports heat as the latent heat of vaporization of a working fluid, and more particularly to a flat plate heat pipe in which a support provided inside a flat plate type closed container is made of a porous material.
[0002]
[Prior art]
A flat plate heat pipe is formed by forming a space sealed by a container with a hollow plate structure and enclosing a condensable fluid as a working fluid in a state where non-condensable gas such as air is deaerated in the space. is there. Since this type of heat pipe has a flat surface, the contact area with the heat exchange object is widened. As a result, heat transfer performance or heat exchange performance is improved, and when used as a means for cooling. Has an advantage that a large heat radiation area can be secured.
[0003]
On the other hand, the flat plate heat pipe has a structure in which only a condensable fluid is sealed in a sealed space portion. Therefore, the working fluid is condensed in a non-operating state or a cooled state without heat input from the outside. The inside of the part is in a high vacuum state. On the other hand, if there is a large amount of heat input from the outside, the working fluid evaporates and increases its volume, so the internal pressure of the sealed space increases. For this reason, in flat plate heat pipes, the rigidity of the wide area of the upper and lower surfaces is low, so that the upper and lower surfaces of the flat heat pipe are deformed when they are not operating or manufactured, or they operate in the opposite direction. Sometimes deformation such as swelling of the upper surface portion and the lower surface portion may occur.
[0004]
In order to eliminate such an inconvenience, in the invention described in Japanese Patent Application Laid-Open No. 11-287578, a plurality of columnar portions are integrally erected inside a thin container having an open upper end and function as a wick. A porous film is formed inside the container by thermal spraying, and after the opening of the container is sealed, gas such as air inside is vacuum degassed and condensable fluid such as water is used as working fluid. We propose a flat heat pipe sealed as
[0005]
[Problems to be solved by the invention]
The flat heat pipe described in the above publication has a structure in which a plurality of columnar portions are connected to a bottom surface portion and a top surface portion having a large area. Therefore, a depression in the bottom surface portion or the top surface portion due to a decrease in internal pressure. It is possible to prevent deformation and bulging deformation of the bottom surface portion or the top surface portion due to an increase in internal pressure during operation. However, the flat plate-shaped heat pipe is formed by spraying a porous film functioning as a wick on the inner surface of a thin container having a plurality of columnar portions therein, so that the manufacturing process is complicated. In addition to this, work with a low material yield is unavoidable, and eventually, the productivity of the flat plate heat pipe is poor and the manufacturing cost is inevitably high. In addition, it is difficult to reliably and uniformly form a porous layer on the outer peripheral surface of the columnar portion and the inner surface of the container by spraying, and as a result, there is a disadvantage that the reflux performance of the working fluid is deteriorated.
[0006]
The present invention has been made paying attention to the above technical problem, and provides a flat plate heat pipe that has a good working fluid recirculation performance and a high productivity, which can reduce the cost. It is intended.
[0007]
[Means for Solving the Problem and Action]
In order to achieve the above object, according to the present invention, a container (sealed container) for enclosing a working fluid is formed of a wick made of a porous sheet having a predetermined shape and a porous material connecting upper and lower flat plate members. It is provided with a support | pillar. Specifically, the invention of claim 1 is a flat plate type airtight container made of a metal having good thermal conductivity, a wick material provided on the inner surface of the flat plate type airtight container, and a thickness of the flat plate type airtight container. In a flat plate type heat pipe comprising a column provided between flat plate portions facing each other in a direction and a condensable working fluid sealed inside the flat plate type airtight container, the wick material is the flat plate A porous sheet formed by sintering fine particles of the same material as the mold closed container, and is provided on the entire surface of the bottom wall portion where the flat form sealed container is not provided with the strut, Is a porous material formed by sintering fine particles of the same material as the flat airtight container, both end surfaces are formed flat, and the both end surfaces are opposed in the thickness direction of the flat airtight container. provided to be connected to the flat plate portion, prior SL-plate sealed container Lid body of the plate sealed container of the same material you formed, on the inner surface of its a be shall and characterized by being formed of a thin plate of the porous sheet is not provided.
[0008]
Therefore, in the first aspect of the invention, the porous sheet formed in a predetermined shape on the inner surface of the flat plate-type container functions as a wick, and the struts connecting the upper and lower flat plate members are also formed from the porous material. It functions as a wick. Thus, according to the first aspect of the present invention, the function of returning the working fluid occurs not only in the porous sheet but also in the support column, so that the return performance of the working fluid is improved. Further, the member causing the reflux performance of such differential fluid, prepared in advance as a sheet or the shaft member, which since it Kumitsukere a flat type container, improves the workability when producing flat-plate heat pipe As a result, inexpensive flat plate heat pipes can be mass-produced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, a specific example of the flat plate type heat pipe of the present invention will be described with reference to the drawings. First, the structure of the container (container) 1 will be described. In FIG. 1, the upper lid 2 is a thin plate made of a metal having good thermal conductivity such as copper, and in the example shown in the figure, it is formed in a rectangular shape. ing. A main body 3 made of the same material as that of the upper lid 2 is provided.
[0010]
The main body 3 includes a bottom wall portion 4 formed of a rectangular flat plate having the shape of the upper lid 2, and a flat side wall portion 5 rising from four sides (edge portions) of the bottom wall portion 4. It is the member of the concave cross-sectional shape comprised by these. Each side wall 5 has a constant height and is set smaller than both the length and width of the bottom wall 4. That is, the main body 3 has an opening width that is greater than or equal to the depth thereof.
[0011]
A porous sheet 6 is attached to the inner surface of the bottom wall portion 4. This porous sheet 6 is formed in a shape that matches the internal structure of the main body 3, that is, as a whole, has a rectangular shape having the same size as the inner area of the bottom of the main body, A through-hole 8 having a shape cut in accordance with the outline of the column 7 is formed.
[0012]
Strut 7 is a structure of a column shape extending in a cylindrical shape as an example, the internal depth of the body portion 3 (i.e., the height between the upper lid 2 and the bottom wall portion 4) and set to the same Has been. Moreover, both the front end surfaces 9 of the support | pillar 7 are formed in the flat surface.
[0013]
The porous sheet 6 and the column 7 are configured by sintering fine particles such as metal or ceramics. The porous sheet 6 is for forming a porous layer that functions as a wick for generating a capillary pressure to flow a working fluid, which will be described later, and the support column 7 improves the return performance of the working fluid, This is to prevent deformation of the container when the container 1 is not operating or operating.
[0014]
A flat plate heat pipe container 1 according to the present invention is configured by fixing and integrating the above-described members. That is, the porous sheet 6 is placed on the inner surface of the bottom wall portion 4 of the main body 3, and the support column 7 is inserted into and fixed to the through hole 8 of the porous sheet 6. For example, when the main body 3 is made of copper and the porous sheet 6 and the support column 7 are formed by sintering copper fine particles, the porous sheet 6 is placed on the inner surface of the bottom wall 4. The three members can be fixed and integrated by sintering by mounting and heating the column 7 to a predetermined temperature in a state where the column 7 is inserted into the through hole 8 formed in the porous sheet 6.
[0015]
Next, the upper lid 2 is placed on the opening in the main body 3. The height of the column 7 the depth of the main body portion 3 (i.e., the height between the upper lid 2 and the bottom wall portion 4) is a set to the same, also the distal end surface 9 of the column 7 with the flat surface Therefore, the front end surface 9 of the support column 7 is in close contact with the inner surface of the upper lid 2. Then, the upper lid body 2, the main body portion 3, and the support column 7 are joined by appropriate means such as welding, brazing, or adhesive.
[0016]
A longitudinal side view and a partially cutaway plan view of the container 1 constructed in this way are shown in FIGS. Then, as shown in FIG. 3, the small diameter tube communicating with the inner portion of the predetermined箇office side wall portion 5 constituting a side surface of the container 1 (nozzle) 10 is attached. This nozzle 10 is used to make the inside of the container 1 into a heat pipe. Specifically, non-condensable gas such as air is exhausted from the inside of the container 1 through the nozzle 10 and condensable working fluid such as water is enclosed. Thereafter, the nozzle 10 is closed. As a method for exhausting such non-condensable gas and subsequently enclosing it in the working fluid, for example, a conventionally known method such as a heat extraction method, a vacuum pump method, or a gas liquefaction method can be employed. . Thus, the flat plate heat pipe 11 is completed. Therefore, a part of the inner surface of the flat plate heat pipe 11 is covered with the porous sheet 6 that matches the size of the inside of the container 1, and the upper lid 2 and the bottom wall portion when not operating and when operating. A support column 7 is attached to prevent deformation in the direction of approaching 4.
[0017]
In the flat plate type heat pipe 11 according to the present invention described above, the porous sheet 6 attached to the inner surface of the bottom wall portion 4 functions as a wick, and holds the liquid-phase working fluid. Therefore, for example, if a heating element such as a CPU (not shown) is attached to the outside of the bottom wall 4 as a heating unit and the upper lid 2 is a heat dissipation unit, the working fluid is heated by the heat of the heating element. Then, it evaporates, and the vapor flows inside the upper lid 2 as a heat radiating part, and dissipates heat to the outside to condense. That is, the working fluid transports heat mainly as its latent heat. Further, a part of the condensed and liquefied working fluid drops toward the inner surface of the bottom wall portion 4, and the other portion returns to the bottom wall portion 4 side serving as a heat generating portion via the support column 7. At the same time, the working fluid is dispersed over the entire surface of the bottom wall 4 by the capillary action of the wick.
[0018]
Thus, according to the above-described flat plate type heat pipe according to the present invention, the vapor of the working fluid is cooled by the heat radiating part (in this example, the upper lid) during operation, and the heat generating part (in this example, the bottom) is cooled by its own weight. At the same time as dropping to the wall part), it can also be refluxed via a support column made of a porous material, so that the working fluid reflux performance is improved. In addition, since there is no need for a thermal spraying process at the manufacturing stage, productivity is improved.
[0019]
In the above specific example, an example of a rectangular flat plate heat pipe is shown. However, the present invention is not limited to the above specific example, and the flat plate heat pipe of an appropriate shape such as a square shape is used. Can also be applied. In this invention, in addition to forming the porous layer by fixing the porous sheet, a structure functioning as a wick such as a narrow groove may be formed on a part of the inner surface of the container. . Moreover, the structure provided in the inner surface of either container may be sufficient as a porous sheet, a porous layer, or a wick. Furthermore, the shape of the support column is not limited to a cylindrical shape, and may be any material that functions as a wick such as an elliptical shape and is made of a porous material that supports the container.
[0020]
【The invention's effect】
As described above, according to the present invention, the porous sheet having a predetermined shape attached to the inner surface of the flat container functions as a wick, and the struts connecting the upper and lower flat plate members are made of the porous material. In this invention, the action of refluxing the working fluid occurs not only in the porous sheet but also in the support column made of the porous material. improves. Also, by adopting a porous sheet and a porous support column, these members are prepared in advance, and a flat heat pipe container can be manufactured by assembling the container. Manufacturing workability of the heat pipe is improved, and as a result, an inexpensive flat plate heat pipe can be mass-produced.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a container in an example of a flat plate heat pipe according to the present invention.
FIG. 2 is a longitudinal side view showing an example of a flat plate type heat pipe according to the present invention.
FIG. 3 is a plan view showing a part of the flat plate type heat pipe according to the present invention in a cutaway manner.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Upper cover body, 3 ... Main-body part, 4 ... Bottom wall part, 6 ... Porous sheet, 7 ... Support | pillar.

Claims (1)

A flat sealed container made of a metal with good thermal conductivity;
A wick material provided on the inner surface of the flat type closed container;
A support provided between the flat plate portions facing each other in the thickness direction of the flat plate-type airtight container;
A condensable working fluid enclosed in the flat-type airtight container;
In a flat plate heat pipe with
The wick material is a porous sheet formed by sintering fine particles of the same material as that of the flat plate-type closed container, and the portion of the bottom wall portion that forms the flat plate-type closed container is not provided with the column. Provided on the entire surface,
The support column is a porous material formed by sintering fine particles of the same material as that of the flat type closed container, both end surfaces are formed flat, and the both end surfaces are in the thickness direction of the flat plate type closed container. It is provided connected to the opposing flat plate part,
Lid body before Symbol same material as the flat plate sealed container that form a flat sealed container is on the inner surface of its, characterized in that it is formed of a thin plate of the porous sheet is not provided Flat plate heat pipe.

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