JP2003302179A - Self-excited oscillation type heat pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-excited oscillation type heat pipe capable of accelerating the movement of a working fluid heated at a heat receiving part and bubbles generated there with a simple structure and capable of guaranteeing the reliability of the performance for a long period of time. <P>SOLUTION: A number of fine fins 10 whose sections are nearly triangular are formed continuously in the length direction on the inner surface of a metal capillary 1. In each fin 10, the inclination of one inclined side surface near the top of the fin and the other inclined side surface is asymmetric. The ratio θ1/θ2 of the angle θ1 to the angle θ2 is 0.5-0.9, and the lead angle β to the tube axis of the fin 10 is 10-35°. The angle θ1 is formed on the section side of the fin 10 by one inclined side surface of the fin 10 and a virtual line A, and the angle θ2 is formed on the section side of the fin 10 by the other inclined side surface of the fin 10 and a virtual line B. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a notebook type personal computer,
The present invention relates to a self-excited vibration heat pipe used as a cooling device for a heat generating portion of a portable communication device such as a mobile phone, a video camera, a fuel cell, a game device, and other portable or easily movable devices.

[0002]

2. Description of the Related Art For example, Japanese Unexamined Patent Publication No. 4-190090 discloses a long elliptical shape (loop shape) in which both ends of a thin tube are connected by a conventional technique (cited in Japanese Unexamined Patent Publication No. Sho 63-318493). A self-excited vibration heat pipe in which one U-shaped turn portion is used as a heat receiving portion and the other U-shaped turn portion is used as a heat radiating portion, and a check valve is installed between the heat receiving portion and the heat radiating portion. Have been described.

[0003]

In the self-excited vibration type heat pipe, when the heat receiving portion is heated, axial vibration is generated in the hydraulic fluid in accordance with the amount of heat, which causes the heat receiving portion to move to the heat radiating portion. Heat transport takes place. However, since only the vibration of the hydraulic fluid does not move the hydraulic fluid from the heat receiving part to the heat radiating part and the heat transfer amount is small, it is necessary to install a check valve (ruby ball valve) in the heat pipe as described above. The circulation of water is promoted and the working fluid heated in the heat receiving portion is moved to the heat radiating portion to improve the heat transport amount. As described above, if a check valve is provided in the heat pipe, the circulation of the hydraulic fluid is promoted, but it is difficult to guarantee long-term reliability of the performance by the check valve, and there are other problems such as high cost. In particular, in the case of an extremely thin pipe, the check valve may rather hinder the circulation of the hydraulic fluid. An object of the present invention is to facilitate the movement of the working fluid heated in the heat receiving portion and the bubbles generated therein to the heat radiating portion with a simple structure, and further, it is possible to guarantee the reliability of performance for a long period of time. It is to provide a self-excited vibration type heat pipe.

[0004]

The self-excited vibration type heat pipe according to the present invention is configured as follows in order to solve the above-mentioned problems. That is, in the self-excited vibration type heat pipe according to claim 1, a large number of fine fins 10 continuous in the length direction and having a substantially triangular cross section are formed on the inner surface of the metal thin tube 1, and The one inclined side surface near the top and the other inclined side surface are characterized in that their inclinations are asymmetric.

A self-excited vibration heat pipe according to a second aspect of the present invention is characterized in that, in a cross section orthogonal to the tube axis of the self-excited vibration heat pipe according to the first aspect, one inclined side surface near the top of the fin 10 is provided. An angle θ1 formed on the cross section side of the fin 10 by an imaginary line A passing through the intersection of the inclined side surface or the extension surface of the inclined side surface and the inner diameter line of the thin tube 1 and orthogonal to the straight line in the radial direction of the thin tube 1. Through the intersection of the other inclined side surface near the top of the fin 10, the inclined surface or the extension surface of the inclined side surface and the inner diameter line of the thin tube 1 and the thin tube 1
Of the imaginary line B orthogonal to the straight line in the radial direction of the angle θ2 formed on the cross section side of the fin 10 (θ1 / θ
2) is characterized by being 0.5 to 0.9.

A self-excited vibration heat pipe according to a third aspect of the present invention is the self-excited vibration heat pipe according to the first or second aspect, in which the lead angle β with respect to the tube axis of the fin 10 is 10 to 10.
It is characterized by being 35 °.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a self-excited vibration type heat pipe according to the present invention will be described with reference to the drawings. First Embodiment FIG. 1 is a partial cross-sectional view of a self-excited vibration type heat pipe according to the first embodiment of the present invention, FIG. 2 is a partial enlarged cross-sectional view of the heat pipe of FIG. 1, and FIG. Is a cross-sectional view showing one half of the fin when bisected by a radial line,
(B) is a sectional view showing the other half of the fin.

On the inner surface of the thin tube 1 made of metal having good thermal conductivity such as copper or copper alloy, aluminum or aluminum alloy, stainless steel, titanium or titanium alloy, the cross section is continuous in the length direction and has a generally triangular cross section. A large number of fine fins 10 are formed, and grooves 11 are formed between the fins 10. The groove bottom wall thickness t of the thin tube 1 in the figure is 0.2 mm, and the inner diameter (groove 1
The diameter of the circle formed by the bottom surface of 1) di is 4 mm, and the fin pitch p (the distance between the tops of adjacent fins 10) is about 0.3 m.
m and fin height h are designed to be 0.20 mm. The fin height h is formed so as to be proportional to the inner diameter di of the thin tube 1 and the fin pitch p in consideration of workability. As a rough guide, when the inner diameter di of the thin tube 1 is 0.5 mm, the fin height h is about 0.02 to 0.12 mm (the optimum value is 0.05 to 0.10 mm), and the inner diameter di of the thin tube 1 is When the height is 5 mm, the fin height h is 0.10 to 0.30.
It is preferable to set each to about mm (the optimum value is 0.15 to 0.25 mm).

The one inclined side surface and the other inclined side surface near the top of each fin 10 in the thin tube 1 are constructed so that their inclinations are asymmetric. That is, in a cross section orthogonal to the tube axis, one inclined side surface near the top of the fin 10 and the inclined side surface (when the inclination does not change to the hem of the fin 10) or its extension surface (inclination at the hem of the fin 10). Is changing from the position near the top) a1
And an inner diameter line of the thin tube 1 (in this specification, "a line connecting the bottom of the groove 11 in the circumferential direction"), an imaginary line passing through an intersection P1 and orthogonal to the straight line a2 in the radial direction of the thin tube 1. The angle formed by A on the cross-sectional side of the fin 10 is θ1, and the other inclined side surface near the top of the fin 10 and the intersection of the inclined surface or the extension surface b1 of the inclined side surface and the inner diameter line of the thin tube 1. When the angle formed by the imaginary line B passing through P2 and orthogonal to the radial line b2 of the thin tube 1 on the cross section side of the fin 10 is θ2, the angle θ1 and the angle θ2 are substantially uniformly different. Is formed. The angle θ
The ratio θ1 / θ2 between 1 and θ2 is preferably in the range of 0.5 to 0.9. The lead angle β (FIG. 1) of the fin 10 with respect to the tube axis is preferably 10 to 35 °.

The self-excited vibration type heat pipe of the first embodiment is industrially manufactured by, for example, a ball rolling method. That is, a floating plug and a grooved plug rotatably held in the floating plug are inserted into a metal shell, and the shell is passed through a die and the floating plug to pull out the shell and reduce the diameter by a predetermined amount. At the position of the grooved plug, the balls arranged at equal angular intervals around the grooved plug are rotated and revolved while pressing the pipe wall of the raw pipe against the surface of the grooved plug, and the groove of the grooved plug is transferred to the inner surface of the raw pipe. By doing so, many fins 10 as described above are continuously formed on the inner surface of the thin tube 1. In addition to the ball rolling method, for example, while rolling out a metal strip material, a large number of fine fins 10 are continuously formed on one surface by a smooth roll and a grooved roll, and the strip material is formed by a forming roll. The fins are rounded in order so that they are on the inside, and are welded continuously (high-frequency induction welding, TIG welding, laser welding, etc.) while abutting both side edges of the strip material, and then circular or polygonal with a sizing roll. It can also be manufactured by molding into other required tubular shapes.

The thin tube 1 having a large number of fins 10 formed on the inner surface thereof as described above is annealed in a reducing atmosphere after the oil content, oxide film and other deposits in the tube have been removed by washing.
Then, for example, as shown in FIG. 4, the thin tube 1 is bent into a U-shape, and the hairpin portions at both ends are mutually Y-shaped.
Are brazed together to form a U-shape. The thin tube 1 connected in this way is vacuum-degassed from the portion of the Y-shaped joint 12, and then sealed with a predetermined amount of hydraulic fluid, and the Y-shaped base is crimped and welded while maintaining the internal vacuum (TIG Welding, high frequency welding, ultrasonic welding, etc.). The working liquid sealed inside is pure water, methane, freon, methanol, freon (R141b, R142b, etc.), cyclopentane, and the like.

The heat pipe constructed as described above is
One of the U-turn portions is used as a heat receiving portion and the other of the U-turn portions is used as a heat radiating portion. The installation portion of the Y-shaped pipe joint 12 is a heat receiving portion or a heat radiating portion, and is preferably used as a heat receiving portion. The reason is that the working liquid condensed in the heat radiating portion can be moved to the heat receiving portion without being hindered by the joint portion due to the capillary action between the fins 10. The heat receiving portion and the heat radiating portion can be arranged in the straight portion of the heat pipe, but in this case also, it is preferable to arrange the pipe joint in the heat receiving portion for the same reason. Thin tube 1
Instead of connecting as shown in FIG. 4, depending on the required cooling capacity, for example, a large number of thin tubes are connected in a meandering manner through a large number of U-shaped turn portions, and finally both ends thereof are connected. Then, it can be implemented as a loop.

In the self-excited vibration type heat pipe of the first embodiment, a large number of fine fins 10 continuous in the length direction and having a substantially triangular cross section are formed on the inner surface of a metal thin tube 1, and each fin 10 is The one inclined side surface and the other inclined side surface at the position near the top are configured such that their inclinations are asymmetric. That is, the angle θ1 formed by one sloping side surface of the fin 10 near the top and the imaginary line A is smaller than the angle θ2 formed by the other sloping side surface of the fin 10 near the top and the imaginary line B. Since the movement from the large angle θ2 side to the small angle θ1 side has a greater resistance than the movement of the hydraulic fluid from the small angle θ1 side to the large angle θ2 side, the movement of the hydraulic fluid is As a result, the movement of the working fluid and the bubbles heated in the heat receiving portion to the heat radiating portion is greatly promoted, and as a result, the heat transport amount is significantly improved.

The ratio θ1 / θ2 of the angle θ1 formed by one of the inclined side surfaces and the virtual line A at the position near the top of the fin 10 and the angle θ2 formed by the other inclined side surface and the virtual line B is 0. When the lead angle β of the fin 10 with respect to the tube axis is 10 to 35 °, the heat transfer amount becomes larger.

Second Embodiment In the heat pipe according to the present invention, the fin 10 has a small sloping surface slower than the sloping side surface near the top as shown in FIG. Even if the inclination of both inclined side surfaces of 10 does not change at the skirt, or both skirts are formed in a concave arc shape (or a convex arc shape) in cross section as shown in FIG. It can be carried out. As shown in FIG. 3, even when both skirts of the fin 10 are formed in a concave arc shape (or a convex arc shape) in cross section, the intersections between the extension surfaces a1 and b1 of the inclined side surfaces and the inner diameter line are virtual. It serves as a reference for the lines A and B.

Test Example Thin tube material = pure copper tube, tube inner diameter di = 4 mm, fin height h
= 0.2 mm, tube wall thickness t = 0.2 mm, fin 1
The angle θ1 of one side surface of 0 and the angle θ2 of the other side surface, and the ratio θ1 / θ2 of the angles θ1 and θ2 are as shown in Table 1, and are respectively configured as shown in FIG. The fin 1 is filled with pure water of 50% of the tube volume.
The lead angle β with respect to the tube axis of 0 is different in the range of 0 to 50 °, and the total length is 160 mm for each of Examples 1 to 3 and Comparative Example 1,
Two heat pipe samples were produced.

Measurement of Limiting Heat Transport Quantity Each sample is connected in a loop shape by a pipe joint 12, and the end of the pipe having a length of 50 mm is heat receiving portion 1a.
Then, the heater 13 was wound around the heat receiving portion 1a and heated. At the other end, the part with a pipe length of 50 mm is attached to the heat dissipation part 1.
c, a cooling box 16 having a cooling water inlet 14 and a cooling water outlet 15 is installed at this portion, and the heat radiating portion 1c is set to 20.
It cooled with the cooling water of (degreeC). The intermediate area between the heat receiving portion 1a and the heat radiating portion 1c of the heat pipe is insulated by a heat insulating material as a heat insulating portion 1b, and the temperature of the cooling water is controlled so that the temperature of each heat insulating portion 1b becomes 50 ° C. while measuring the temperature of each portion with a thermocouple. Was controlled, and the heating temperature was raised until dryout was performed to measure the limit heat transport amount.

Table 1

The measurement result of the limit heat transport amount is shown in FIG. 5, and according to this result, the ratio θ1 / θ2 between the angle θ1 of one side surface of the fin 10 and the angle θ2 of the other side surface is 0.
When the lead angle β with respect to the tube axis of the fin 10 is 10 to 35 ° in the range of 5 to 0.9, Comparative Example 1
(Θ1 / θ2 = 1, that is, when both surfaces of the fin are symmetrical) and Comparative Example 2 (θ1 / θ2 = 0.36) show a higher heat transport amount. When the value of θ1 / θ2 is 1 or close to 1 (when the inclinations of both side surfaces of the fin 10 are symmetrical or nearly symmetrical) as in conventional heat pipes, the hydraulic fluid vibrates on the spot. It is probable that the working fluid heated in the heat receiving part did not move to the heat radiating part, and as a result, high performance could not be exhibited.

As is clear from the result of FIG. 5, θ1 / θ
The maximum limit heat transfer amount is shown when the value of 2 is around 0.7, but when the value of θ1 / θ2 becomes smaller than 0.5, the grooves between the fins 10 become shallow or crushed, As a result, it is considered that the capillary force between the fins is reduced and the heat transport capability is reduced. If the fin spacing is increased as a countermeasure, the capillary force is reduced due to the widening of the fin spacing, which has the opposite effect. When the lead angle β of the fin 10 with respect to the tube axis is 10 to 35 °, especially when it is around 20 °, the heat transfer amount increases most. However, if the lead angle β of the fin exceeds 35 °, the space between the fins increases. It is considered that due to the capillary force of, the movement of the hydraulic fluid in the axial direction is reduced and the heat transport amount is reduced.

[0021]

According to the self-excited vibration type heat pipe of the first aspect of the present invention, a large number of fine fins 10 which are continuous in the length direction and have a substantially triangular cross section are formed on the inner surface of each fin 10. The one inclined side surface and the other inclined side surface at the position near the top are configured such that their inclinations are asymmetrical, and directivity is given to the movement of the working fluid heated in the heat receiving portion, and the heat receiving portion The movement of the heated working fluid and bubbles to the heat radiating section is greatly promoted, and as a result, the heat transport amount is significantly improved. In addition, the configuration is simple and long-term reliability of performance can be guaranteed.

According to the self-excited vibration type heat pipe of the invention of claim 2, in the cross section orthogonal to the tube axis, one inclined side surface near the top of the fin 10 and the inclined side surface or the extension of the inclined side surface. An angle θ1 formed on the cross-sectional side of the fin 10 by an imaginary line A passing through the intersection of the surface and the inner diameter line of the thin tube 1 and orthogonal to the straight line in the radial direction of the thin tube 1,
An imaginary line that passes through the intersection of the other inclined side surface near the top of the fin 10 and the inclined surface or the extended surface of the inclined side surface and the inner diameter line of the thin tube 1 and is orthogonal to the radial straight line of the thin tube 1. The angle θ formed by B and the cross section side of the fin 10
Since the ratio with 2 (θ1 / θ2) is 0.5 to 0.9, the above effect is most effectively exhibited.

According to the self-excited vibration type heat pipe of the third aspect of the present invention, since the lead angle β of the fin 10 with respect to the tube axis is 10 to 35 °, the heat transport amount is further increased.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a self-excited vibration type heat pipe according to a first embodiment of the present invention.

2 is a partially enlarged cross-sectional view of the heat pipe of FIG. 1, where (a) is a cross-sectional view showing a half of the fin when the fin is divided into two lines in the radial direction, and (b) is the fin. It is sectional drawing which shows another one-half part.

FIG. 3 is a partially enlarged sectional view showing a modification of the self-excited vibration type heat pipe according to the embodiment of the present invention.

FIG. 4 is a schematic front view for explaining a method of measuring a limit heat transport amount of a self-excited vibration type heat pipe.

FIG. 5 is a diagram showing a critical heat transport amount of each heat pipe sample.

[Explanation of symbols] 1 thin tube 10 fins 11 grooves 12 pipe fittings 13 heater 14 Inlet 15 Outlet 16 cooling box 1a Heat receiving part 1b Heat insulation part 1c Heat dissipation part β-fin lead angle θ1, θ2 angle t Groove thickness h fin height di tube inner diameter a1, b1 extension line a2, b2 radial straight line p1, p2 intersection A, B virtual line

Claims (3)

[Claims] 1. A fine fin (1) which is continuous in the lengthwise direction with an inner surface of a metal thin tube (1) and has a substantially triangular cross section.
0) is formed in a large number, and one inclined side surface near the top of each fin (10) and the other inclined side surface are asymmetric in inclination, and a self-excited vibration type heat pipe. 2. An intersection of one inclined side surface near the top of the fin (10), the inclined side surface or an extension surface of the inclined side surface and an inner diameter line of the thin tube (1) in a cross section orthogonal to the tube axis. And an imaginary line (A) that passes through and is orthogonal to the radial straight line of the thin tube (1) forms an angle (θ1) formed on the cross-sectional side of the fin (10) and the top of the fin (10). An imaginary line (B) passing through the intersection of the other inclined side surface, the inclined surface or the extension surface of the inclined side surface and the inner diameter line of the thin tube (1), and orthogonal to the radial straight line of the thin tube (1). The self-excitation according to claim 1, characterized in that the ratio (θ1 / θ2) to the angle (θ2) formed on the cross section side of the fin (10) is 0.5 to 0.9. Vibratory heat pipe. 3. The self-excited vibration heat pipe according to claim 1, wherein a lead angle (β) of the fin (10) with respect to the tube axis is 10 to 35 °.