JP2003302180A - 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 improving the heat transportation efficiency by the capillary action without preventing the self-excited oscillation for the stability of the performance. <P>SOLUTION: The heat pipe is characterized by a number of fine fins 10 continuously formed in the length direction on the inner surface of a metal capillary 1. It is preferable that the ratio (h)/ (di) of the height (h) of the fin 10 to the inner diameter (di) of the capillary 1 is 0.01-0.35, and the ratio (n)/(di) of the number of the fins (n) to the inner diameter (di) of the capillary is 3-25. It is also preferable that the lead angle θ to the tube axis in the fin 10 is 0-20°, and the inner diameter of the capillary 1 is 0.5-5 mm. <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 In a self-excited vibration type heat pipe, when the heat receiving part is heated, axial vibration is generated in the working fluid corresponding to the amount of heat, which causes heat transfer from the heat receiving part to the heat radiating part. Be seen. As described above, the heat transfer of the self-excited vibration type heat pipe is theoretically the heat transfer due to the axial vibration of the working fluid, and therefore it is necessary to suppress the vibration damping due to the axial reciprocation as much as possible. In Japanese Patent Laid-Open No. 19090, it is proposed that the inner surface of the loop type small diameter tube container is processed to be as smooth as possible by polishing with a chemical means. Further, in JP-A-60-178291, in order to strengthen the capillary force in the heat pipe and increase the heat transport amount, a wick made of a mesh of about 0.1 mm is filled in the pipe with a small diameter pipe. Is proposed.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
If the inner surface of the small-diameter tube is polished and extremely smoothed, as described in JP-A-0, the hydraulic fluid in the inside tends to vibrate, and in that sense, heat transfer is promoted. It was necessary to make the diameter of the pipe smaller (making it an ultra-fine pipe) because of the smaller size. However, although the heat transfer amount per unit area of extra-fine tubes increases, the overall heat transfer amount is small, so in order to secure the necessary heat transfer amount, increase the number of thin tubes or loop type thin tube. It is necessary to increase the number of turns of the heat pipe, the space occupancy rate of various equipment of the heat pipe itself increases, and it goes against the demand for miniaturization of equipment,
It was more expensive. On the other hand, JP-A-60-178
As described in Japanese Patent No. 291, the filling of a small-diameter pipe with a fine mesh wick is extremely expensive because the wick itself is expensive and the filling process is also expensive. . Also, in portable equipment, it is necessary to maintain cooling performance even when the cooling device that uses the heat pipe is overturned, but with such a wick type heat pipe, in such a case, the top heat performance is better than the bottom heat performance. Also greatly decreases, which is a cause of impairing the stability of performance. An object of the present invention is to provide a self-excited vibration type heat pipe which has a simple structure to improve the heat transport efficiency by exhibiting a capillary action without interfering with the self-excited vibration, and moreover, has stable performance. It is in.

[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, the self-excited vibration type heat pipe according to claim 1 is characterized in that a large number of fine fins 10 continuous in the length direction are formed on the inner surface of the metal thin tube 1.

The self-excited vibration type heat pipe according to claim 2 is the self-excited vibration type heat pipe according to claim 1, wherein the ratio h / di between the fin height h of the fin 10 and the pipe inner diameter di.
= 0.01 to 0.35, the number of fins n and the inner diameter of the pipe d
The ratio to i is n / di = 3 to 25.

A self-excited vibration heat pipe according to a third aspect is the self-excited vibration heat pipe according to the first or second aspect, in which the lead angle θ with respect to the tube axis of the fin 10 is 0 to 2.
The feature is that it is set to 0 °.

The self-excited vibration heat pipe according to claim 4 is the self-excited vibration heat pipe according to any one of claims 1 to 3, wherein the thin tube 1 has an inner diameter of 0.5 to 5 mm. I am trying.

[0008]

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 sectional view of a self-excited vibration type heat pipe according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view of the heat pipe of FIG. 1, and FIG. 3 is a portion of the heat pipe of FIG. Expanded cross section,
FIG. 4 is a schematic front view of the heat pipe of FIG. 1 connected in a loop shape.

A large number of fine fins 10 continuous in the longitudinal direction are formed on the inner surface of the thin tube 1 made of a metal having good thermal conductivity such as copper or copper alloy, aluminum or aluminum alloy, stainless steel, titanium or titanium alloy. There is a groove 11 between the fins 10. The thin tube 1 has a wall thickness (groove bottom wall thickness) t of 0.2 mm, a tube inner diameter (circular diameter formed by the bottom surface of the groove 11) di of 0.5 mm to 5 mm, and a fin pitch p.
(The distance between the tops of the adjacent fins 10) is 0.2 mm or more. The fin height h is formed so as to be proportional to the inner diameter di of the thin tube 1. As a rough guide, if the inner diameter di of the thin tube 1 is 0.5 mm or 5 mm, the fin height h
Are 0.05 to 0.10 mm and 0.15 to 0.2, respectively.
It is preferably set to about 5 mm. On the fin hem,
If necessary, an inclined surface slower than the inclined surfaces on both sides of the upper portion can be formed, or the portion can be formed in a concave arc shape or a convex arc shape.

The ratio h / di between the fin height h of the fin 10 and the pipe inner diameter di is in the range of 0.01 to 0.35, and the ratio n / di between the number of fins n and the pipe inner diameter di is 3 to 25. It is set to each range. Lead angle θ with respect to the tube axis of the fin 10
Is preferably 0 to 20 °.

The self-excited vibration type heat pipe of the first embodiment is industrially manufactured by 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 described above, a number of fine fins 10 are continuously formed on one surface by a smooth roll and a grooved roll while feeding a metal strip material, and the strip material is formed by a forming roll. Are sequentially rounded so that the fin forming surface is on the inside, and welded continuously while abutting the side edges of the strip (high frequency induction welding, TIG welding, laser welding, etc.)
However, it can also be manufactured by forming this into a required tubular shape such as a circular shape, a polygonal shape or the like by using a sizing roll.

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 are 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 configured 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 fluid condensed in the heat radiating portion can be smoothly 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. Instead of connecting the thin tubes 1 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 tubes are connected. It can also be implemented by connecting the ends. Further, both pipe ends may not be connected depending on the case where the required cooling capacity is small or depending on the target equipment.

In the self-excited vibration type heat pipe of the first embodiment, since a large number of fine fins 10 continuous in the length direction are formed on the inner surface of the metal thin tube 1, the inner surface of the tube is formed by the mutual capillary action of the fins 10. It can be wet and maintain stable heat transport performance. Further, the ratio h / di between the fin height h of the fin 10 and the pipe inner diameter di is 0.01 to 0.35, and the ratio n / di between the number of fins n and the pipe inner diameter di is 3 to 25.
By setting the above, the above-mentioned effects can be more effectively exhibited. Further, the lead angle θ with respect to the tube axis of the fin 10 is 0 to 20.
By setting it within the range of °, the above-mentioned effect can be exerted even better. By setting the inner diameter of the thin tube 1 to 0.5 to 5 mm, the effect of self-excited vibration is better exhibited without impeding the vibration of the hydraulic fluid.

Test Example 1 Example group The sample tube inner diameter di, the fin height h, the number of fins, etc. are different as shown in Table 1 and are connected in a loop as shown in FIG. Self-excited vibration type heat pipe sample 5
Seed produced. Thin tube material = Pure copper tube Tube thickness t = 0.2 mm Lead angle θ = 0 ° with respect to tube axis of fin 10 Heat pipe total length = 160 mm Filled hydraulic fluid = Pure water of 50% of pipe volume

Table 1

Comparative Example 1 group sample tube inner diameter di 6 mm, 4 mm, 1 mm, 0.5 mm,
Five self-excited vibration type heat pipe samples of Comparative Example 1 group as described below were manufactured having a thickness of 0.3 mm and having a smooth inner surface and connected in a loop shape as shown in FIG. Capillary material = Pure copper tube Tube thickness t = 0.2 mm Heat pipe total length = 160 mm Filled hydraulic fluid = Pure water of 50% of pipe volume

Comparative Example 2 group sample tube inner diameter di 6mm, for the sample of 4mm, wire diameter 0.1
mm woven copper wire, pipe inner diameter di 1mm,
0.2 mm wire diameter for 0.5 mm and 0.3 mm samples
Each of the wicks woven with the copper wire is laminated on the inner wall surface of the pipe in a two-layer structure and connected in a loop shape as shown in FIG.
Seed produced. Capillary material = Pure copper tube Tube thickness t = 0.2 mm Heat pipe total length = 160 mm Filled hydraulic fluid = Pure water of 50% of pipe volume

Measurement of critical heat transport amount Pipe length 5 at the end of the pipe joint 12 side of each sample
The 0 mm portion was used as the heat receiving portion 1a, and the heater 13 was wound around the heat receiving portion 1a to heat it. A portion of the other end having a pipe length of 50 mm is used as a heat radiating portion 1c, a cooling box 16 having an inlet 14 and an outlet 15 of cooling water is installed in this portion, and the heat radiating portion 1c is cooled by 20 ° C. Cooled. 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, the heating temperature was raised until dry out, and the limiting heat transport amount (W) was measured. The limit heat transfer amount is when the sample is horizontal (Fig. 5), when the heat receiving part is positioned at the top and the sample is vertically placed (top heat mode) (Fig. 6), and when the heat receiving part is positioned at the bottom. And the sample is placed vertically (bottom heat mode)
(FIG. 7) and measured respectively.

The results of the measurement of the limit heat transport amount are shown in FIGS. 5 to 7. According to these results, the heat pipe sample of the example shows that the inner surface without fins is As compared with the smooth self-excited vibration type heat pipe sample, the heat transfer amount could be stably secured. This is because the fins 10 on the inner surface of the pipe were able to efficiently transfer heat without hindering the vibration of the hydraulic fluid.
This is because the hydraulic fluid was heat-transported from the heat radiating portion to the heat receiving portion due to the capillary phenomenon generated between the fins immediately before the dry-out.
However, when the inner diameter of the tube is less than 0.5 mm, the fins on the inner surface impede the vibration of the working fluid, and although the self-excited vibration occurs, the heat transfer performance is slightly lower than that of the sample having a smooth inner surface. On the other hand, if the pipe inner diameter exceeds 5 mm, the self-excited vibration effect becomes small. The heat pipe having a wick on the inner surface like the sample of Comparative Example 2 group performed the heat transfer smoothly by the capillary phenomenon of the wick in the bottom heat mode and exhibited the performance close to that of the sample of the Example group, but the capillary tube in the top heat mode. It is considered that the performance was extremely low as compared with the sample of the example group because the force was weak and the wick hindered the self-excited vibration of the hydraulic fluid.

Test Example 2 (Relationship between Fin Height and Heat Transport Amount) This is the same as the sample having the tube inner diameter di = 4 mm among the samples of the above Examples, and the fin height h is 0 to 1.7 mm.
A heat pipe sample was manufactured in which the fin height h / the pipe inner diameter di was changed in the range of 0 to 0.43, and the heat transport amount was measured with each sample in a horizontal state. It was shown to. Comparing the results of FIG. 8 and the results of FIG. 5, as shown in FIG. 8, the limit heat transport amount is 40 W or more when the fin height h / the pipe inner diameter di is in the range of 0.01 to 0.35. In FIG. 5, the heat transfer amount of the self-excited vibration type heat pipe sample with an inner diameter of 4 mm and a smooth inner surface was 4
When both 0 W and 36 W, which is the heat transfer amount of a self-excited vibration heat pipe sample having an inner diameter of 4 mm and a wick on the inner surface, are exceeded and h / di is in the range of 0.01 to 0.35, comparison It can be seen that a larger heat transfer amount can be obtained as compared with the examples.

Test Example 3 (relationship between the number of fins and the amount of heat transport) Among the samples of the above-mentioned examples, the sample was the same as the sample having the tube inner diameter di = 4 mm and the number of fins n was 0 to 110 (the number of fins n / Heat pipe samples were manufactured in which the pipe inner diameter di was changed in the range of 0 to 27.5), and the heat transport amount was measured for each of the samples in a horizontal state. The results are shown in FIG. When the results of FIG. 9 and the results of FIG. 5 are compared, as shown in FIG. 9, the number of fins n / the pipe inner diameter di is 3 to 2
The critical heat transport amount within the range of 5 is 40 W or more.
In both cases, the heat transfer amount of the self-excited vibration heat pipe sample having an inner diameter of 4 mm and a smooth inner surface was 40 W, and the heat transfer amount of the self-excited vibration heat pipe sample having an inner surface of 4 mm and a wick was 36 W. , N / di
It can be seen that a larger amount of heat transport can be obtained when the value is in the range of 3 to 25 as compared with Comparative Examples and the like.

Test Example 4 (Relationship between the Lead Angle θ with respect to the Fin Tube Axis and the Heat Transport Amount) Similar to the sample of the tube inner diameter di = 4 mm among the samples of the above-mentioned Examples, the lead with respect to the fin tube axis was used. Angle θ
Was manufactured in the range of 0 to 40 °, and the heat transfer amount was measured for each of the samples with the sample in a horizontal state. The results are shown in FIG. 10. Comparing the results of FIG. 10 with the results of FIG. 5, when the lead angle θ with respect to the tube axis of the fin is 0 to 20 °, a larger heat transport amount can be obtained as compared with the heat pipe sample of the comparative example. I understand.

[0024]

According to the self-excited vibration type heat pipe of the first aspect of the present invention, since a large number of fine fins 10 continuous in the lengthwise direction are formed on the inner surface of the metal thin tube 1, the fin 1
It is possible to wet the inner surface of the tube by mutual zero capillary action and maintain stable heat transport performance.

According to the self-excited vibration type heat pipe of the present invention, the ratio h / di between the fin height h of the fin 10 and the pipe inner diameter di is set to 0.01 to 0.35, and the number of fins is set. By setting the ratio n / di between n and the inner diameter di of the pipe to 3 to 25, the above-mentioned effect is more effectively exhibited.

According to the self-excited vibration type heat pipe of the third aspect of the present invention, the effect is further enhanced by setting the lead angle θ of the fin 10 to the tube axis within the range of 0 to 20 °. It

According to the self-excited vibration type heat pipe of the fourth aspect of the present invention, the effect of self-excited vibration is obtained without inhibiting the vibration of the working fluid by setting the inner diameter of the thin tube 1 to 0.5 to 5 mm. Better demonstrated.

[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.

FIG. 2 is an enlarged cross-sectional view of the self-excited vibration heat pipe of FIG.

FIG. 3 is a partially enlarged development sectional view of the self-excited vibration type heat pipe of FIG.

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 the measurement results of the limit heat transport amount in the horizontal posture of each heat pipe sample group.

FIG. 6 is a diagram showing the measurement results of the critical heat transport amount in the top heat mode of each heat pipe sample group.

FIG. 7 is a diagram showing the measurement results of the critical heat transport amount in the bottom heat mode of each heat pipe sample group.

FIG. 8 is a diagram showing a relationship between fin height and heat transport amount in the self-excited vibration type heat pipe according to the present invention.

FIG. 9 is a diagram showing the relationship between the number of fins and the amount of heat transport in the self-excited vibration type heat pipe according to the present invention.

FIG. 10 is a diagram showing a relationship between a lead angle of a fin with respect to a tube axis and a heat transport amount in a self-excited vibration type heat pipe according to the present invention.

[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 θ Fin lead angle t Tube groove bottom thickness h fin height di tube inner diameter

Claims (4)

[Claims] 1. A self-excited vibration type heat pipe, characterized in that a large number of fine fins (10) continuous in the longitudinal direction are formed on the inner surface of a metal thin tube (1). 2. Fin height (h) of said fin (10)
(H / di) = 0.01 to 0.
35, the ratio of the number of fins (n) to the inner diameter of the pipe (di) (n / d
The self-excited vibration type heat pipe according to claim 1, wherein i) = 3 to 25. 3. The lead angle (θ) of the fin (10) with respect to the tube axis is 0 to 20 °.
Alternatively, the self-excited vibration heat pipe according to item 2. 4. The thin tube (1) has an inner diameter of 0.5 to 5 mm.
The self-excited vibration type heat pipe according to any one of claims 1 to 3, wherein