JP2000028281A - Plate type heat pipe and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an effective wick structure without inserting a separate wick member into a hole by reducing a thickness by pressing a flat porous tube formed by partitioning therein into many pores by partition walls, and forming infinitesimal gaps at corners bent by buckling the walls. SOLUTION: In a flat porous tube 10, sections of pores 103 are each formed substantially in a parallelogram and partition walls 102 for partitioning the adjacent pores 103 are obliquely inclined with respect to a main surface of the tube 10. The tube 10 is reduced in its thickness by pressing, and the walls 102 are buckled. Thus, infinitesimal gaps are formed at the bent corners, and the gap is formed from three surfaces of an acute angle. The gap becomes a wick structure for developing a capillarity of working fluid at the time of forming a container by using the tube 10. Accordingly, a sufficient wick structure can be realized without inserting a wick member such as a mesh or the like separately in the pores 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat heat pipe having a flat shape.

[0002]

2. Description of the Related Art In recent years, a technique of cooling a heat-generating component such as a semiconductor element mounted on an electric device such as a personal computer has been attracting attention. One of the methods is a cooling technique using a heat pipe. As a cooling method using a heat pipe,
Typically, a heat pipe is attached to a heat-generating component, and the heat of the heat-generating component is transported to a heat-radiating fin or the like and dissipated through the heat pipe. In recent years, a plate-shaped heat pipe, which is easy to be brought into contact with a heat-generating component and to which heat-dissipating fins and heat-sink blocks are easily attached, is often used.

[0003] The heat pipe is briefly described as follows.
The heat pipe has a cavity that is sealed inside,
A certain amount of a working fluid (also referred to as a working fluid) such as water or alternative Freon is stored in the cavity. The inside of the cavity is evacuated, so that the working fluid is easily evaporated. The working fluid exists in a mixed state of a liquid phase and a gas phase (steam) in the cavity.

[0004] In the heat pipe, the working fluid in the hollow portion evaporates, and the vapor moves, so that the heat transfer function operates.
For example, in the case of a heat pipe of a straight type, when heat is applied from one end of the heat pipe (this part is called a heat absorbing part of the heat pipe), the working fluid in a liquid phase in the heat absorbing part evaporates, and the Moves to the other end side, where the vapor condenses and radiates heat (this part is called the heat radiating part of the heat pipe). If fins or the like are attached to the heat radiating portion of the heat pipe, the heat of the working fluid vapor is easily radiated to the outside.

[0005] If the working fluid condensed in the heat radiating section does not return to the heat absorbing section, the above operation does not continue. Therefore, it is necessary to return (reflux) the working fluid (liquid phase) condensed in the heat radiating section to the heat absorbing section. Normally, the liquid phase of the working fluid condensed in the heat radiating portion is lowered by gravity by positioning the heat absorbing portion below the heat radiating portion. Such a state may be called a bottom heat mode.

[0006]

However, depending on the equipment on which the heat-generating component to be cooled is mounted, the heat pipe used for the cooling structure may not always be used in the bottom heat mode. This is because, for example, in the case of a portable personal computer or the like, the personal computer may be used in an inclined state or the like depending on the usage mode. Further, it may be difficult to arrange the heat pipe so as to be in the bottom heat mode state, because the arrangement of the cooling structure is limited by the structure of the device on which the heat generating component to be cooled is mounted.

By the way, conventionally, even when the heat absorbing portion is located above the heat radiating portion (referred to as a top heat mode),
Various heat pipe structures have been proposed in which the reflux of the working fluid is maintained. Such an operation in the top heat mode is sometimes called a reverse operation. In general, a method is known in which a working fluid is caused to flow upward by using a capillary action.

As a typical method for realizing the capillary action, there is a method in which a mesh, a wire, or the like is provided in a hollow portion of a heat pipe. The mesh and the wire utilize the capillary force obtained in a gap between the mesh and the inner wall of the cavity. The diameter of the wire constituting the mesh, the number of meshes, and the like are selected in consideration of the type of the working fluid, the amount of heat input, and the like. While such a mesh can easily obtain a relatively effective capillary force, the trouble of the insertion step is a problem in terms of manufacturing cost and the like.

In addition to the method of installing a mesh or the like in a cavity, there is a groove tube in which a fine groove is formed on the tube wall (the inner wall of the cavity). The groove tube is expected to have a capillary action by the groove.

Recently, as a heat pipe for cooling a heat-generating component such as a semiconductor element, a plate-type (also called a flat type, a flat type, a thin type, etc.) type heat pipe has been used due to the problems of improvement in heat transport efficiency and space for installation. Pipes are being developed and put into practical use. As such a plate-type heat pipe, a container using a flat multi-hole tube produced by extruding an aluminum material or the like with multiple holes has appeared.

However, in the case of such a flat multi-hole tube-type plate heat pipe, the size of each of the plurality of arranged holes is small, and the shape of the holes is often rectangular, so that the conventional heat pipes are not provided. The work of inserting the mesh into each of the holes has not been easy from the viewpoint of assembly cost. From the viewpoint of capillary force expression, it is desirable that the mesh be as close as possible to the inner wall, but if the hole is rectangular,
There is also a problem that it is difficult to insert the mesh as close as possible to its inner wall.

In addition to a method of inserting a mesh or the like into each hole of the flat multi-hole pipe, a method of forming a groove on the inner wall thereof is also conceivable, but a groove is formed on the inner wall of the hole of the flat multi-hole pipe. This is not easy from the viewpoint of processing technology such as extrusion technology. Particularly, it is difficult to form grooves having a narrow pitch by extrusion. Further, a method of forming a groove by further processing after manufacturing a flat multi-hole tube is technically difficult and not practical in terms of manufacturing cost.

If the shape of each hole of the flat multi-hole tube is made to be a complicated shape including an acute angle portion, a capillary action can be expected in principle. However, it is difficult to manufacture such a flat multi-hole tube at least at a practical cost.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made to provide a practical flat multi-hole tube type plate heat pipe having a wick structure. That is, the plate-type heat pipe of the present invention includes a container in which the partition wall is buckled and deformed, which is formed by subjecting a flat multi-hole pipe in which holes partitioned by the partition wall are arranged in parallel to a reduction in thickness by rolling down. It is.

It is preferable that each of the partitions rises obliquely with respect to the main surface on a wall portion corresponding to the main surface of the plate type heat pipe. In this case, it is particularly preferable that the partition wall rises obliquely at an angle of 45 ° or less with respect to the main surface.

Further, the adjacent partition walls may rise up obliquely on the wall corresponding to the main surface of the plate-type heat pipe so that the inclination directions are alternately different.

The present invention is a plate-type heat pipe in which the above-mentioned buckled deformed partition has a wick structure and exhibits a capillary action of a working fluid. It is particularly effective when the thickness of the container is 2 mm or less as such a plate-type heat pipe.

[0018] As a method of manufacturing a plate-type heat pipe of the present invention, a step of reducing the thickness of a flat multi-hole tube in which holes partitioned by partition walls are arranged in parallel in the plate thickness direction by rolling down the plate, and buckling the partition walls. A step of sealing the flat multi-hole tube and performing heat pipe processing.

As the thickness reduction by the above-mentioned reduction, a process of pressing in a thickness reduction direction or a rolling process is preferable. In addition, as a flat multi-hole tube used for thickness reduction by reduction,
It is preferable to use a partition whose wall is inclined with respect to the thickness direction. It is particularly preferable that the partition wall is inclined at an angle of 45 ° or less with respect to the main surface of the flat multi-hole tube.

In the flat multi-hole pipe used for the thickness reduction by such reduction, the cross section of the hole partitioned by the partition may be trapezoidal, parallelogram or triangular.

In the above-mentioned thickness reduction by reduction, it is desirable that the compression ratio is 30% or more. In other words, it is desirable to crush the sheet thickness to 0.7 or less of the thickness before the thickness reduction processing by the reduction.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a flat multi-hole tube used for a plate type heat pipe of the present invention. As shown in (a), the flat multi-hole pipe 10 in which a plurality of holes 103 are arranged in parallel is subjected to a press working or a rolling work to compress in the thickness direction. FIG. 1 (a) is an enlarged view of a part of the flat multi-hole tube 10 of FIG. 1 (a). As shown, the cross section of the hole 103 is substantially a parallelogram, and The partitioning walls 102 are obliquely inclined with respect to the main surface of the flat multi-hole tube 10. The tilt angle is not particularly limited, but is, for example, 45 °. Although not easy in terms of extrusion technology, this angle should be as acute as possible, for example 45
° or less is desirable.

Now, the flattened multi-hole tube 10 is subjected to thickness reduction by rolling down, thereby causing the partition wall 102 to buckle as shown in FIG. The deformation state of the partition 102 shown in FIG. 1 (c) is schematically shown. The buckled and bent partition wall 102 has a small gap at the bent corner.

By the way, the degree of compression of the above-mentioned thickness reduction by reduction may be determined in consideration of the length and inclination of the partition wall 102, the wall thickness thereof, and furthermore the size and material of the flat multi-hole tube 10, etc. If the compression ratio is set to 30% or more, the partition 10
It is desirable that the buckling condition of 2 is sufficient.

In the flat multi-hole tube 10 before the thickness reduction process by the reduction is performed, the partition wall 102 is formed by the flat multi-hole tube 1.
It is good to incline the main surface of 0 from the beginning. It is desirable that the angle be as acute as possible, for example, about 45 °. After the reduction in thickness by the reduction, the angle of the partition wall 102 to the main surface of the flat multi-hole tube 10 does not usually change much except for the buckled portion.

The gap generated by the buckling of the partition wall 103 is formed by three surfaces having acute angles. This gap has a wick structure that exhibits a capillary action of a working fluid in a plate-type heat pipe in which a container is formed using the flat multi-hole tube 10. Therefore, the plate type heat pipe is
A sufficient wick structure is realized without separately inserting a wick member such as a mesh or a wire into the hole 103. In addition, when inserting a wire or a mesh, the wick member may move and shift, but in the case of the present invention, the wick gap is practically immovable.

Further, in the plate type heat pipe of the present invention, since the vapor flow path and the liquid flow path are substantially separated, the flow path resistance is reduced. Therefore, excellent heat transfer performance is realized.

[0028]

EXAMPLE 1 Example 1 will be described with reference to FIG. The flat multi-hole tube 10 is a 60 mm wide and 3 mm thick extruded aluminum material. Excluding both side parts, bottom 2.5mm, height 2m
21 parallel parallelogram holes 103 of about m are provided in parallel. The partition 102 separating the hole 103 has a thickness of 0.3
mm, and is inclined by 45 ° with respect to the main surface of the flat multi-hole tube 10.

The flat multi-hole tube 10 was pressed to a thickness of about 2 mm using a conventional press. The compression ratio is 33
%. Initially, 2mm
The hole 102 having the height of was crushed to a height of about 1 mm.
Along with this, the partition wall 102 buckled as schematically shown in FIG. At this time, the inclination of the continuous portion between the main surface walls 100 and 101 constituting the upper and lower main surfaces of the flat multi-hole tube 10 and the partition wall 102 is almost unchanged. Also, the main surface walls 100, 10
The thickness of the partition wall 102 except for the thickness of 1 and the buckled portion is also substantially unchanged.

After the partition wall 102 was buckled in this manner, both ends of the flat multi-hole tube 10 were sealed. At this time, the inside of the cavity is evacuated to a vacuum, unnecessary oil is removed, and a proper amount of a working fluid such as CFC substitute is housed before sealing. Further, as shown in FIG. 3, the sealing of both ends was performed by a method of welding separately prepared cap members 104 to both ends of the flat multi-hole tube 10. The cap member 104 is provided with a hollow portion 1040, and the hollow portion 1040 is provided.
40 ensures that the holes 103 communicate with each other at both ends after joining. The removal of unnecessary gas and the like at the time of sealing was performed by the same method as that for manufacturing a normal heat pipe.

It was confirmed that the plate-shaped heat pipe thus manufactured was able to maintain a certain degree of reflux of the working fluid even in the reverse operation state, due to the effect of the wick structure of the buckled partition 102.

Embodiment 2 This will be described with reference to FIG. The flat multi-hole tube 11 has a width of 40
It is an extruded member made of aluminum having a thickness of 2.2 mm and a thickness of 2.2 mm. Except for both sides, substantially trapezoidal holes 113 having an upper base of 0.8 mm and a lower base of 4 mm are provided side by side. There are 14 holes including the holes 1130 on both sides. The partition wall 112 separating the holes 113 from each other or between the hole 113 and the hole 1130 has a thickness of 0.3 mm and is inclined by 45 ° with respect to the main surface of the flat multi-hole tube 11. Principal wall 11 constituting both principal surfaces of flat multi-hole tube 11
The thickness of 0, 111 is 0.3 mm.

The flat multi-hole tube 11 was rolled by a rolling mill and crushed to a thickness of 1.5 mm. The compression ratio is about 32%. By this rolling, the hole 113, which was initially 1.6 mm high, was crushed to a height of about 0.9 mm. Accordingly, the partition 112 buckled as shown. At this time, the main surface walls 110, 1 constituting the upper and lower main surfaces of the flat multi-hole tube 11
As in the first embodiment, the inclination of the continuous portion between the partition 11 and the partition 112 was substantially unchanged.

Next, both ends of the flat multi-hole tube 11 are sealed. Prior to this, the partition walls 112 at both ends are removed by about 5 mm in the depth direction of the tube. The situation is shown in FIG. Thereafter, one end was caulked and then sealed by welding, and after a predetermined amount of working fluid was stored, the other end was similarly sealed. The operation of removing unnecessary internal gas and the like prior to sealing is the same as in the case of a conventional heat pipe. As described above, the partition walls 11 at both ends are provided.
2 was partially removed in the depth direction of the pipe because the holes 1 at both ends were removed.
12 is intended to communicate.

It was confirmed that the plate-shaped heat pipe thus manufactured was able to maintain a certain degree of recirculation of the working fluid even in the reverse operation state due to the effect of the wick structure of the buckled partition wall 112.

[0036]

As described above, the flat multi-hole tube-type heat pipe of the present invention and the method of manufacturing the same do not require a separate operation of inserting a wick member such as a mesh or a wire into the hole, which is effective. Wick structure is realized,
An extremely practical effect such as a reduction in manufacturing cost is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a flat multi-hole tube used for a plate-type heat pipe of the present invention.

FIG. 2 is a diagram illustrating a flat multi-hole tube according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a part of the manufacturing process of the plate-type heat pipe in the example of the present invention.

FIG. 4 is a diagram illustrating a part of the manufacturing process of the plate-type heat pipe in the example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flat multi-hole tube 100 Main surface wall 101 Main surface wall 102 Partition wall 103 hole 11 Flat multi-hole tube 110 Main surface wall 111 Main surface wall 112 Partition wall 113 Hole 1130 Hole 104 Cap member 1040 Hollow portion

Claims (11)

[Claims] 1. A flat multi-hole pipe in which holes partitioned by a partition wall are arranged in parallel, formed by performing a thickness reduction process by rolling down.
A plate-type heat pipe including a container in which the partition wall is buckled. 2. The plate type heat pipe according to claim 1, wherein each of said partition walls rises obliquely with respect to said main surface on a wall portion corresponding to a main surface of said plate type heat pipe. 3. The plate-type heat pipe according to claim 2, wherein each of said partition walls rises obliquely at 45 ° or less with respect to said main surface on a wall portion corresponding to a main surface of said plate-type heat pipe. 4. The partition wall according to claim 2, wherein each of the adjacent partition walls rises obliquely on a wall portion corresponding to a main surface of the plate-type heat pipe so that inclination directions are alternately different. Plate type heat pipe. 5. The plate-type heat pipe according to claim 1, wherein a wick structure is realized by the buckled and deformed partition walls. 6. The plate-type heat pipe according to claim 1, wherein the container has a thickness of 2 mm or less. 7. A step of reducing the thickness of a flat multi-hole tube in which holes partitioned by a partition are arranged in parallel in a thickness direction thereof by rolling down to buckle the partition, and sealing the flat multi-hole tube. A method for manufacturing a plate-type heat pipe, comprising a step of heat pipe processing. 8. The method for manufacturing a plate-type heat pipe according to claim 7, wherein the thickness reducing process is a pressing process in a thickness reducing direction or a rolling process. 9. The flat multi-hole tube to be subjected to the thickness reducing process, wherein the partition wall is inclined at an angle of 45 ° or less with respect to a main surface of the flat multi-hole tube. A method for producing the plate-shaped heat pipe according to the above. 10. The flat multi-hole tube to be subjected to the thickness reducing process according to any one of claims 7 to 10, wherein a cross section of a hole partitioned by the partition wall is trapezoidal, parallelogram, or triangle. A method for producing the plate-shaped heat pipe according to the above. 11. The method for manufacturing a plate-type heat pipe according to claim 7, wherein the thickness reduction processing has a compression ratio of 30% or more.