JPH10170180A - Heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pipe which is free from deformation of an end part for injecting or discharging a working fluid. SOLUTION: In a heat pipe 1 in which a condensing fluid being deaired in vacuum is sealed into a closed pipe tube 2 as container 3, an end part 4 as an injection/discharge part of a working fluid out of the container 3 is sealed up by at least two squeezed parts 5 made concave in the radial direction of the container 3. squeezed parts 5 are so arranged as to have substantial isotropy in the radial direction from the center point in the radial direction of the container 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe for transporting heat as latent heat of a working fluid, and more particularly to a sealing structure at an end thereof.

[0002]

2. Description of the Related Art As is well known, a heat pipe is a device in which a condensable fluid such as water or sodium is sealed as a working fluid in a container such as a sealed metal tube that has been degassed under vacuum. Automatically operates, and the working fluid evaporated in the high-temperature portion flows to the low-temperature portion to be radiated and condensed, so that heat is transported as latent heat of the working fluid. Therefore,
It is necessary to completely seal the end of the heat pipe so as not to cause the inflow of air and leakage of the working fluid, and therefore, in general, a method of performing both crimping and welding as a means for sealing the end is conventionally used. Has been taken.

[0003] In this case, the end of the working fluid at the injection pipe side is sealed when the working fluid has already been injected into the container and the internal pressure is lower than the atmospheric pressure, and when the container is heated. However, special considerations need to be taken into account because the working fluid evaporates and its internal pressure rises above atmospheric pressure. It is proposed by Japanese Patent Publication No. 56-24875.

[0004] The invention described in this publication will be briefly described. A short pipe projection is formed by swaging one end of a copper pipe or the like serving as a heat pipe container, and the short pipe projection is formed. The portion is crushed in the radial direction into a semicircular cross section, and the tip is welded and sealed. Then, in order to crimp the short tube protrusion into the above shape, as shown in FIGS. 7A, 7B and 7C,
Die-equivalent receiving member 1 having concave portion 10 having a semicircular cross section
This is a method in which a cylindrical short tube projecting portion 13 is pressed into a semicircular shape by a pressing member 12 corresponding to a punch having a hemispherical or semi-cylindrical column shape whose tip is smaller than the radius of the concave portion 10. .

The heat pipe manufactured as described above has an apparent thermal conductivity that is several times to several tens times that of a metal such as copper or aluminum. It is used in various heat-related devices, for example, a CPU or MP provided in a notebook-type or sub-notebook-type portable personal computer.
It is used for cooling of U (arithmetic processing unit).

Since this type of personal computer is intended to be portable, the internal heat is released to the outside by heat transfer without providing an air-cooling fan for miniaturization and weight reduction. More specifically, CP which is a heat generating portion
U and MPU are connected to an aluminum alloy electromagnetic shielding plate or the like provided on the back surface of the display via a heat pipe.

Therefore, according to the above cooling structure, when the CPU or the MPU generates heat with the use of the personal computer, the heat is transmitted to the heat pipe container,
The internal operation is heated and evaporates. The working fluid vapor flows toward the other end having a low pressure, and is condensed there by being deprived of heat by the electromagnetic shielding plate. That is, heat is transmitted from the working fluid to the electromagnetic shielding plate, and further released from the surface of the electromagnetic shielding plate to the outside. As a result, the CPU and MPU are cooled, and overheating is prevented.

[0008]

As described above, since a portable personal computer is required to be small and light, the clearance between existing members or the clearance between those members and the personal computer case is extremely low. Is usually narrower, and is 1 mm or less at extreme locations. On the other hand, in the cooling structure of the personal computer using the heat pipe, the heat pipe prevents heating and temperature rise of components and various wirings permanently installed in the personal computer, and also, to prevent the damage thereof. It must be placed so that it does not come in contact with those parts.

However, in the heat pipe described in JP-B-56-24875, the short pipe projection 13 which is crushed into a semicircular shape and slightly sealed outwardly with respect to the central axis. There was a possibility that it would be warped or warped. This is considered to be because the magnitude of the residual stress differs between the upper portion and the lower portion in FIG. 6 of the crushed portion.

Therefore, if the crushed portion is curved or warped, it cannot be arranged in a non-contact manner with an existing component provided in the personal computer. In order to solve such inconvenience, it is necessary to perform post-processing such as correction of the sealing end, and as a result, there has been an inconvenience that the manufacturing process of the entire heat pipe is increased and the cost is increased. That is, the above heat pipe is not suitable for a cooling structure of a portable personal computer, and there is much room for improvement.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat pipe in which a working fluid injecting / discharging end has no deformation.

[0012]

Means for Solving the Problems and Action Therefor To achieve the above-mentioned object, the present invention according to the first aspect of the present invention is directed to a method of forming a condensable fluid in a closed metal tube serving as a container in a vacuum degassed state. In the heat pipe in which the working fluid is sealed, the end portion of the container serving as the injection / discharge portion of the working fluid is sealed by at least two crushing portions that are concave in the radial direction of the container,
The crushed portions are arranged so as to have substantially isotropy in a radial direction about the center point in the radial direction of the container.

Therefore, according to the first aspect of the present invention, the crushing portion is a portion where the container is crushed in the radial direction,
Residual stress accompanying deformation is generated in each crushed portion. In that case, the crushed portions are arranged to be isotropic with each other in the radial direction centered on the center point in the radial direction of the container, and the residual stress generated in each crushed portion is substantially uniform. For this reason, the end of the container that has formed the crushed portion does not bend or warp.

According to a second aspect of the present invention, there is provided a heat pipe in which a condensable fluid is filled as a working fluid in a vacuum degassed state inside a sealed metal pipe serving as a container, wherein An end portion serving as an injection / discharge portion of the end portion is crushed and sealed into a shape having a cross-sectional shape perpendicular to a center axis of the end portion, which is point-symmetric with respect to the center axis, and sealed. Is what you do.

Therefore, according to the second aspect of the present invention, the residual stress due to strain or deformation at a symmetrical position with respect to the center axis of the crushed and sealed end is maintained in a balanced state. The end of the container, which serves as the working fluid injection / discharge portion, is unlikely to bend or warp.

According to a third aspect of the present invention, there is provided a heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a sealed metal tube serving as a container. Is characterized in that an end portion serving as an injection / discharge portion is crushed and sealed into a shape having a plurality of symmetry axes in a cross section perpendicular to the center axis of the end portion.

Therefore, according to the third aspect of the present invention, the residual stress caused by the strain or deformation at the respective symmetrical portions in the two directions intersecting each other at the crushed and sealed end is maintained in a balanced state. Due to the drooping, the ends of the container serving as the working fluid injecting / discharging portions are unlikely to be curved or warped.

Further, the invention according to claim 4 is a heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum-degassed state inside a sealed metal tube serving as a container, The end portions serving as the injection / discharge portions are crushed and sealed from a plurality of directions along the radial direction so that the respective crush amounts are substantially equal to each other.

Therefore, according to the fourth aspect of the present invention, the crushed portions having almost no difference in the magnitude of the residual stress are provided at a plurality of locations on the outer peripheral portion of the end portion, and the residual stresses are reduced. Since they are in balance with each other, the ends of the container that serve as the injection and discharge portions of the working fluid do not bend or warp.

According to a fifth aspect of the present invention, there is provided a heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum-degassed state inside a sealed metal pipe serving as a container, wherein End portions to be injection / discharge portions are crushed and sealed in at least three directions along the radial direction, and are formed in a shape having projections projecting in at least three directions along the radial direction. It is a feature.

Therefore, according to the fifth aspect of the present invention, since the crushed portions are in at least three directions, and the resulting projections act as reinforcing ribs, they serve as the working fluid injection / discharge portions of the container. No bending or warping occurs at the ends.

Further, the invention described in claim 6 is characterized in that the opening angles between the projections are made equal to each other with respect to the heat pipe according to the invention described in claim 5.

Therefore, according to the sixth aspect of the present invention, the magnitude of the residual stress generated in the crushed portion becomes more uniform, so that the aforementioned end portion of the container is less likely to be bent or warped. .

According to a seventh aspect of the present invention, there is provided a heat pipe according to any one of the first to sixth aspects of the present invention, wherein an end portion serving as an injection / discharge portion is crushed and sealed. It is characterized in that the front end side of the stopped portion is welded and sealed.

Therefore, according to the invention of claim 7, since the molten metal generated at the time of welding acts as a plug for closing an end portion serving as an injection / discharge portion, the container is more securely sealed.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIG.
This will be described with reference to FIG. The heat pipe 1 shown in this specific example has a container 3 made of a copper pipe having a circular cross section as an example. One end of this container 3 is riveted into the end face and then brazed, or the end is cold. It is sealed by a conventionally known means such as a method of soldering after press-contact processing. A predetermined amount of a working fluid (not shown) such as water or alcohol is sealed inside the container 3.

On the other hand, the other end of the container 3
An injection pipe portion 4 smaller in diameter than the container 3 is provided in a state of protruding on the same axis. In addition, this injection pipe part 4
Is formed by means such as swaging the container 3 itself or brazing a separately prepared thin tube of circular cross section made of the same material as the container 3.

In the position of the injection pipe portion 4 leaving a predetermined length on the distal end side, it becomes concave toward the center axis from the four directions of the outer peripheral portion thereof and extends to some extent along the length direction of the injection pipe portion 4. A crushed portion 5 having a length L is formed. Each of the crushing portions 5 has a configuration in which the inner surfaces are in close contact with each other, that is, the injection tube portion 4 is sealed by these four crushing portions 5.
The sealed portion of the injection tube 4 is a sealed end 6. Therefore, four projections 7 projecting radially from the central axis are formed on the sealing end 6. That is, the sealing end 6 has a cross section in the radial direction X
It is shaped like a letter (or cross).

Further, in this specific example, each crushing portion 5
Originally, the outer periphery of the injection pipe portion 4 having a convex circular arc shape is formed into a substantially right-angled V-shaped groove at the four outer peripheral portions, and is depressed so as to have the same crushing amount. The crushing portions 5 are arranged at regular intervals on the outer peripheral surface of the injection pipe portion 4, that is, on the circumference. In other words, the opening angles of the protrusions 7 are set to be equal.

Further, the tip end of the sealing end 6 is subjected to welding means such as welding or brazing, and is sealed with a spherically solidified molten metal. In addition, this welding part 8
It may be provided as needed, that is, a structure in which the injection tube portion 4 is sealed with only the crushing portion 5 may be employed. The injection pipe portion 4 itself does not bend or warp in the radial direction, and has a so-called linear shape.

Next, a procedure for manufacturing the heat pipe having the above-described configuration will be described. First, a copper pipe 2 having, for example, a circular cross section, which has been cut into a predetermined length in advance, is prepared as a material of the container 3, and one end of the pipe 2 is sealed by various conventionally known methods. In addition, the other end of the pipe 2 is swaged or the like, so that the injection pipe 4 has a small diameter.
To form Then, the inner surfaces of the pipe 2 and the injection pipe section 4 are degreased and cleaned. As the cleaning means, conventionally known means such as cleaning using an appropriate solvent or ultrasonic cleaning can be adopted.

Next, the pipe 2 is made into a heat pipe.
That is, pure water as a working fluid, for example, is injected into the inside of the pipe 2 slightly more than a prescribed amount via the injection pipe section 4, and the pipe 2 is heated by appropriate means to remove non-condensable gas. Perform an eviction. Then, the non-condensable gas dissolved in the working fluid is discharged to the outside of the pipe 2 from the opening end of the injection pipe 4 together with the vapor of the working fluid. Therefore, the amount obtained by subtracting the amount expelled as steam from the total amount of the working fluid previously sealed in the pipe 2 is the substantial amount of working fluid.

As a method for degassing and enclosing the working fluid in the inside of the pipe 2, a vacuum pump method, a gas liquefaction method, or the like can be employed in addition to the above-mentioned heating expelling method. It is also possible to adopt a method in which the pressure inside the pipe 2 is increased while the distal end portion is temporarily sealed, and then the working fluid is flushed by opening the temporary sealed portion.

Next, the injection tube 4 is sealed. More specifically, as shown in FIGS. 2 (A), (B), (C) and (D), a non-crushed portion 9 of a predetermined length is left on the tip side of the injection tube portion 4. The part is crushed in its radial direction and crimped. The processing is performed, for example, by holding the injection pipe portion 4 in an upright state along the vertical direction, and pressing a punch (not shown) having a tip shape corresponding to the shape of the crushed portion 5 from the outer peripheral side of the injection pipe portion 4. The tube is advanced toward the injection pipe portion 4 in four directions along the radial direction, and the outer peripheral portion of the injection pipe portion 4 is crushed.

The amount of advance of the punches, that is, the amount of pushing into the injection pipe portion 4 is set so that the interval between the punches is not more than twice the thickness of the injection pipe portion 4. Therefore,
Since the meat portion (peripheral wall portion) of the injection pipe portion 4 is completely sandwiched between the punches, the inner surfaces of the injection pipe portion 4 come into close contact with each other and the injection pipe portion 4 is sealed.

In this manner, 4 on the circumference of the injection pipe 4
The crushed portions 5 are evenly arranged at the positions. In other words, the crushing portions 5 have an isotropic arrangement in the radial direction with the central axis of the injection pipe portion 4 as the center point. Thereby, four protrusions 7 sandwiched between the crushed portions 5 are formed. That is, the entire inner surface of the injection pipe portion 4 comes into close contact with each other in an X-shape, and the pipe 2 is pressed and sealed at each crushing portion 5 of the injection pipe portion 4. In addition, the process of forming the crushed portion 5 may be performed at four locations at a time, two locations facing each other, or one location at a time.

In each of these cases, a residual stress is generated in each of the four crushed portions 5, and the residual stress in each of the crushed portions 5 is substantially equal in size. Four pieces that are arranged at substantially equal intervals on the circumference of the injection pipe part 4 so that residual stresses generated in the crushed parts 5 cancel each other, and that the four pieces extend along the length direction of the injection pipe part 4. Since the projection 7 acts as a reinforcing rib, the sealing end 6 maintains a linear shape without being curved or warped.

The injection tube 4 crushed as described above is cut into a predetermined length. Here, the non-crushed portion 9
Is cut on the edge side of the sealing end 6 so as to leave a margin for welding. Then, the pipe 2 is erected vertically so that, for example, the injection pipe portion 4 faces upward, and the non-crushed portion 9 remaining at the tip of the injection pipe portion 4 in this state is welded or brazed. I do.

In this case, since the non-crushed portion 5 remains hollow, the molten metal generated by heating fills the hollow portion, and the molten metal above the hollow portion is
It becomes spherical and solidifies on the upper side of the crushed portion 5. This part is
The welded portion 8 is formed. The cutting step may be performed as needed, and may be performed before the crushing step. Further, the cutting position may be, for example, a point in the middle of the sealing end 6 or a boundary point between the sealing end 6 and the non-crushed portion 9.

FIG. 1 is a view showing a state after crushing and welding have been performed as described above. As shown here, in the above-described method, the crimping portion 5 remains as it is, and the distal end side thereof is welded. The molten metal is solidified in a plug (plug) state, and the pipe 2 is sealed by both the crimping portion 5 and the welding portion 8.

As described above, according to the heat pipe 1, the residual stresses in the injection pipe portion 4 are substantially uniform in magnitude over the entire circumference and cancel each other. Functions as a reinforcing rib, the sealing end 6 maintains a linear shape. In addition, heating during welding
There is no bending due to temperature rise. Therefore,
It can be employed as a cooling element for a CPU or MPU of a portable personal computer without any post-processing.

Further, in the above specific example, the X-shaped sealing end 6 has been exemplified, but the sealing end 6 is crushed in at least three directions toward the center axis thereof, and is radially Any cross-sectional shape having protrusions protruding in at least three directions may be used. Other specific examples will be described below.

The shape of the sealing end 6 shown in FIG. 3 is such that the cross section in the radial direction is a Y shape having three crushed portions 5 and three protruding portions 7.
It is a type. According to this configuration, the crushed portion 5 to be formed
Has the advantage of simplifying the manufacturing process. Also, since the projection 7 acts as a reinforcing rib,
The injection pipe portion 4 does not bend or warp, and can maintain a linear shape.

The shape of the sealing end 6 shown in FIG. 4 has a star-shaped cross section in the radial direction having six crushed portions 5 and six protruding portions 7. These crushing portions 5 have the same crushing amount. That is, they are crushed in six directions toward the center axis, and have a cross-sectional shape in which the crushing amounts are equal. According to this configuration, since a large number of protrusions 7 acting as reinforcing ribs are provided in the radial direction, the isotropy is further improved, and the injection pipe portion 4 does not bend or warp, and maintains a linear shape. can do.

Further, the shape of the sealing end 6 shown in FIG. 5 includes two crushed portions 5 whose radial cross-sections are vertically opposed, and two crushed portions 5 which are horizontally opposed. It is H-shaped with four projections 7. That is, the cross-sectional shape has two symmetry axes in the vertical and horizontal directions in the figure. According to this configuration, the shape is symmetrical in the vertical direction in the figure, and the projections 7 serving as the reinforcing ribs extend in the symmetrical directions with respect to each other.

The shape of the sealing end 6 shown in FIG. 6 includes two crushed portions 5 whose radial cross-sections are opposed in the vertical direction, and four projections 7 provided on both left and right sides thereof. H type with More specifically, this sealing end 6
6, the width of the crushed portion 5 in FIG. 6 is larger and the height of each protrusion 7 is smaller than that of the H-shaped sealing end 6 shown in FIG. In addition, each protrusion 7 is formed by a surplus portion formed as a result of forming the crushed part 5 by crushing the injection pipe part 4 in the vertical direction.

Therefore, the sealing end 6 of this shape also has a cross-sectional shape having two axes of symmetry in the vertical and horizontal directions. According to this configuration, since the protruding portion 7 serving as a reinforcing rib extends symmetrically in the up-down direction, in particular, not only is it unlikely that warpage in the up-down direction occurs, but also the crushing step from the left-right direction is unnecessary, There is also an advantage that the manufacturing process is simplified as compared with the sealing end 6 having the shape shown in FIG.

In the above-described specific example, the heat pipe in which the sealing end 6 is formed in the injection pipe portion is exemplified. However, the present invention is not limited to the above-described specific example, and the sealing end 6 of the container may be sealed. A heat pipe having a configuration in which the toe 6 is provided, in other words, a configuration in which the injection pipe portion is not provided can also be provided. Further, in the above specific example, a container having a circular cross section has been described as an example. However, the container shape may be, for example, an oval cross section.

[0049]

As is apparent from the above description, according to the first aspect of the present invention, at least two ends of the container, which become the injection and discharge portions of the working fluid, are concave in the radial direction of the container. Since the crushed portions are sealed by the individual crushed portions and are arranged so as to have substantially isotropy in a radial direction about the center point in the radial direction of the container, injection is performed. A heat pipe having no curved or warped end portion serving as a discharge portion can be obtained. As a result, it is possible to obtain a heat pipe suitable for cooling a device having a limited internal space such as a portable personal computer.

Further, in any of the second to sixth aspects of the present invention, a device which does not cause bending or warping due to crushing for sealing and has a large internal space restriction as in the first aspect of the present invention. A suitable heat pipe can be obtained.

Further, according to the seventh aspect of the present invention, since the distal end side of the injection tube portion is welded to the sealed portion, the container can be more securely sealed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a heat pipe according to the present invention.

FIG. 2 is a schematic view showing a cross section of an injection tube section in the specific example.

FIG. 3 is a schematic view showing a sealed end having a Y-shaped cross section.

FIG. 4 is a schematic view showing a sealed end having a star-shaped cross section.

FIG. 5 is a schematic view showing a sealing end having an H-shaped cross section.

FIG. 6 is a schematic diagram showing an H-shaped sealing end having a low sectional shape.

FIG. 7 is a sectional view showing a conventional technique.

[Explanation of symbols]

1 ... heat pipe, 2 ... pipe, 3 ... container,
4 ... injection tube part, 5 ... crushed part, 6 ... sealed end, 7 ... projection, 8 ... welded part, 9 ... non-crushed part.

Claims (7)

[Claims] 1. A heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a sealed metal tube serving as a container, wherein an end portion of the container serving as a working fluid injection / discharge portion. Are sealed by at least two crushed portions that are concave in the radial direction of the container, and the crushed portions are substantially radially centered on the radial center point of the container. A heat pipe, which is arranged so as to have isotropic properties. 2. A heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a sealed metal tube serving as a container, wherein an end portion of the container serving as a working fluid injection / discharge portion. The heat pipe is characterized in that the end is sealed by being crushed into a shape having a point symmetrical cross section perpendicular to the center axis with respect to the center axis. 3. A heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a sealed metal pipe serving as a container, wherein an end portion of the container serving as a working fluid injection / discharge portion. Wherein the heat pipe is sealed by being crushed into a shape having a plurality of symmetry axes in a cross section perpendicular to a center axis of the end. 4. A heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a sealed metal tube serving as a container, wherein an end portion serving as a working fluid injection / discharge portion of the container. However, the heat pipe is characterized in that the heat pipe is sealed by being crushed in a plurality of directions along the radial direction so that the respective crush amounts are substantially equal to each other. 5. A heat pipe in which a condensable fluid is sealed as a working fluid in a vacuum degassed state inside a sealed metal tube serving as a container, wherein an end portion of the container serving as a working fluid injection / discharge portion. Wherein the heat pipe is formed by being crushed and sealed in at least three directions along the radial direction and having a projection protruding in at least three directions along the radial direction. 6. The heat pipe according to claim 5, wherein the opening angles between the protrusions are equal to each other. 7. An end portion serving as the injection / discharge portion,
The heat pipe according to any one of claims 1 to 6, wherein a front end side of the crushed and sealed portion is welded and sealed.