JPH1047889A - Boiling cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiling cooler, low in cost and capable of roughing a boiling surface easily. SOLUTION: The refrigerant tank of a boiling cooler is constituted of an extruded member 7, formed by extrusion work, and a cap, applied on the lower end surface of the extruded member 7. The extruded member 7 is provided with vapor passages 9, a condensed liquid passage 10 and non-operating passage 11, while the vapor passages 9 are divided into small passages 9a by a plurality of pieces of ribs 13. The vapor passages 9 (small passages 9a) are passages, through which vapor refrigerant, boiled and evaporated by receiving heat of a heat generating body, ascends, and a multitude of recesses and projections are formed on the inner wall surface thereof. The recesses and projections are formed so that particles R are injected into the passage from one opening end of the vapor passage 9 employing an injection nozzle 15 and the particles R are collided against the inner wall surface of the vapor passage 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling cooling device for cooling a heating element by repeatedly boiling and condensing a refrigerant.

[0002]

2. Description of the Related Art Conventionally, it has been generally known that in a boiling cooling apparatus, the number of air bubbles generated on the boiling surface is increased by roughening (roughening) the boiling surface to improve heat radiation performance. ing. Several methods have been proposed for roughening the boiling surface, as described below. For example, a method of plating the surface with a plating solution containing a dispersing material, and then dissolving the dispersing material exposed from the plating film to form a cavity in the surface (Japanese Patent Publication No. 59-25040), has a wide inside and a small opening. A method of forming a large number of minute spaces (Japanese Patent Publication No. 59-3)
No. 9679, Japanese Patent Publication No. 23717/1990, and a method of thermally adhering a screen mesh to the surface (Japanese Patent Application Laid-Open No. 60-202297).

[0003]

However, the concavo-convex shape contributing to the promotion of boiling is on the order of microns, and it is extremely expensive to roughen the boiling surface in units of microns by each of the above methods. In addition, when the boiling surface exists inside the container, machining is physically impossible, so that it is extremely difficult to apply each of the above methods to the boiling cooling device. SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and an object of the present invention is to provide a low-cost, easy-to-coarse boiling cooling apparatus having a roughened boiling surface.

[0004]

According to the first aspect of the present invention, particles are injected into the hollow interior from the open end of the hollow body forming the refrigerant tank, and the collision of the particles causes irregularities on the inner wall surface of the hollow body. It is formed. According to this method, the boiling surface can be roughened even if the boiling surface exists inside the container (that is, inside the hollow body). Further, since it is only necessary to spray particles into the hollow body, the processing can be completed easily in a short time, and the boiling surface can be roughened at low cost.

According to the second aspect of the present invention, the refrigerant tank is arranged such that the opening end on the injection side where the hollow particles are injected is directed upward. When particles are ejected from one of the open ends of the hollow body, the degree (roughness) of the irregularities formed by the collision of the particles increases as the particles are closer to the open end on the ejection side (the surface is rougher). ), The degree of unevenness decreases (the surface becomes smoother) as the distance from the opening end on the ejection side increases. Therefore, by arranging the injection-side opening end having a rougher surface upward, the boiling heat transfer in the upper part in the refrigerant tank can be improved and the heat radiation performance can be improved.

According to the third aspect, irregularities due to collision of particles are formed only on the inner wall surface of the vapor passage of the hollow body. Boiling the refrigerant can be promoted by roughening the inner wall surface of the vapor passage. On the other hand, since the condensed liquid condensed and liquefied by the radiator flows down in the condensed liquid passage, it is better to suppress the boiling (foaming) of the refrigerant in the condensed liquid passage and roughen the inner wall surface of the condensed liquid passage. Has the opposite effect in terms of improving heat dissipation.

According to the fourth aspect of the present invention, the hollow body forming the refrigerant tank has fine irregularities formed on the inner wall surface by extrusion molding. The boiling of the refrigerant can be promoted by roughening the inner wall surface of the hollow body by the fine irregularities. According to this extrusion molding, even if the boiling surface exists inside the container (that is, inside the hollow body), the boiling surface can be easily roughened (at low cost) in a short time.

According to the means of claim 5, irregularities due to the collision of particles are formed only on the inner wall surface of the steam passage provided in the hollow body. Similarly to the means of claim 3, roughening the inner wall surface of the steam passage can promote the boiling of the refrigerant. On the other hand, it is better to suppress the boiling (foaming) of the refrigerant in the condensate passage, and roughening the inner wall surface of the condensate passage has an adverse effect in terms of improving heat dissipation.

According to the means of claim 6, particles are injected into the hollow interior from the open end of the steam passage of the extruded hollow body, and the collision of the particles forms irregularities on the inner wall surface. In this way, by forming fine irregularities on the inner wall surface of the steam passage by extrusion molding, and further forming irregularities due to particle collision, the number of bubbles generated on the boiling surface can be further increased, and the heat dissipation performance Can be further improved.

According to the means of claim 7, the particles injected into the hollow body of the hollow body have a particle size of 100 to 1000 μm. The irregular shape effective for forming the bubble nucleus necessary when the refrigerant boils is on the order of microns, and the irregular shape of the millimeter unit does not easily contribute to the formation of the bubble nucleus. Therefore, in order to form irregularities on the order of microns, the particle size of the particles should be 100 to
It is desirable that the thickness be 1000 μm.

According to the means of claim 8, the uneven shape is set to be larger as approaching the radiator. In the refrigerant tank near the radiator, the temperature of the refrigerant becomes high and it is difficult for the refrigerant to absorb heat. However, the above configuration makes it easier to absorb heat.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a cooling apparatus according to the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a front view of a boiling cooling device, and FIG. 2 is a side view of the boiling cooling device. Boiling cooling device 1 of the present embodiment
Is for cooling the heating element 2 by the transfer of boiling heat of the refrigerant, and includes a refrigerant tank 3, a connecting portion 4, a radiator 5, and a cooling fan (not shown). The heating element 2 is, for example, an IGBT module that constitutes an inverter circuit of an electric vehicle or a general power control device, and is tightened with a bolt (not shown) in a state where the heat radiation surface of the heating element 2 is in close contact with the outer wall surface of the refrigerant tank 3. It is fixed to the refrigerant tank 3.

The coolant tank 3 is made of an extruded material 7 (FIG. 3) formed by extruding, for example, an aluminum block material.
) And a cap 8 to be placed on the lower end surface of the extruded material 7. As shown in FIG. 3A, the extruded material 7 is provided in a flat shape having a small thickness with respect to the lateral width, and has a steam passage 9 penetrating in the extrusion direction (vertical direction in FIG. 3B). It has a liquid passage 10 and a non-operating passage 11. The steam passage 9, the condensate passage 10, and the non-operating passage 11 are defined by a plurality of passage walls 12 extending in the pushing direction, and the steam passage 9 is further divided into small passages 9 a by a plurality of ribs 13 extending in the pushing direction. ing. Further, a screw hole 14 for screwing a bolt for fixing the heating element 2 is formed in each passage wall 12.

The vapor passage 9 is a passage through which the vapor refrigerant vaporized by the heat of the heating element 2 rises, and is formed in parallel at the center of the extruded material 7 corresponding to the mounting portion of the heating element 2. I have. However, each steam passage 9 (small passage 9a) has a large number of irregularities (not shown) formed on the inner wall surface. As shown in FIG. 4, the irregularities are formed by injecting particles R into the inside of the vapor passage 9 from one open end of the vapor passage 9 using an ejection nozzle 15 and colliding with the inner wall surface of the particles R. . FIG. 5 shows the degree of unevenness (surface roughness) formed by the collision of the particles R. 5 (a) shows the surface roughness before the treatment, FIG. 5 (b) shows the surface roughness near the ejection side opening end after the treatment, and FIG. 5 (c) shows the surface roughness near the non-ejection side opening end after the treatment. Shows the surface roughness. (Injection conditions) Length l of the steam passage 9: 270 mm Processing time: 10 seconds Injection material (particle R): alumina oxide (Al ₂ O ₃ ) Particle size of the injection material (particle R): 420 to 590 μm Working air pressure: 2-6 kgf / cm ² Air supply port: 3/8 inch

The condensed liquid passage 10 is a passage through which the condensed liquid cooled and liquefied by the radiator 5 flows, and is formed at a position off the mounting portion of the heating element 2. Non-operating passage 11
Are formed on the side opposite to the condensate passage 10 in the width direction of the extruded material 7. The condensate passage 10 and the non-operating passage 11
No irregularities are formed on the inner wall surface, and the state of the inner wall surface obtained by extrusion is maintained. The cap 8 is made of the same aluminum as the extruded material 7, and is covered on the outer periphery of the lower end of the extruded material 7 and brazed. However, cap 8
Is placed on the opening end (lower end in FIG. 4) of the extruded material 7 on the side opposite to the ejection side. That is, the extruded material 7 contains the particles R inside the steam passage 9.
The opening end on the ejection side that has ejected is directed upward.
Between the cap 8 and the lower end surface of the extruded member 7, there is provided a communication passage 16 which communicates each of the passages 9, 10, 11 formed in the extruded member 7 (see FIG. 1).

The connecting portion 4 is composed of two molding plates 17 (see FIG. 6) press-molded into an oval shape, and a flat space formed by the two molding plates 17 is connected to one communication chamber. A separator 18 (see FIG. 7) partitioning the other communication chamber (not shown) is provided above the refrigerant tank 3 and hermetically connects the refrigerant tank 3 and the radiator 5. As shown in FIG. 6, the forming plate 17 has elliptical recesses 170 (forming plate 1) at both ends in the longitudinal direction.
7 are provided from the inside to the outside, and communication holes 171 and 172 (holes punched at the time of pressing) are opened in the respective recesses 170. However, one communication port 1
71 is an opening near the top of the concave portion 170 having an elliptical shape,
The other communication port 172 opens toward the lower part of the recess 170. That is, in the up-down direction of the forming plate 17 (up-down direction in FIG. 6), one communication port 171 is opened at a position higher than the other communication port 172. Also, the forming plate 17 has arc-shaped reinforcing ribs 17 at the lower part of one communication port 171 and the upper part of the other communication port 172, respectively.
3 are provided. The outer peripheral edges of the two molding plates 17 except for the lower ends are joined to form a flat space inside.

The separator 18 comprises two molded plates 1
7 is disposed near the other communication port 172 of the flat space formed by the pressure chamber 7 (see FIG. 1), and the lower end surface thereof is the upper end surface of the passage wall 12 that partitions the vapor passage 9 and the condensate passage 10 of the refrigerant tank 3. It is brazed in contact with. This separator 1
8 is press-formed into an outer shape (see FIG. 7) corresponding to the inner circumferential shape of the flat space formed by the two forming plates 17, and its outer peripheral edge is brazed to the inner wall surface of each forming plate 17. Have been. A plurality of inner fins 19 are inserted into one communication chamber of the connecting portion 4. As shown in FIG. 1, the inner fin 19 is
Are supported by a plurality of positioning ribs 174 provided at the bottom. However, each inner fin 19 is formed so that the vapor refrigerant flowing out from the vapor passage 9 of the refrigerant tank 3 can flow toward one communication port 171 through one communication chamber.
The connecting portions 4 are arranged in the longitudinal direction, and a gap is secured between the inner fins 19.

The radiator 5 is a so-called Dron cup type heat exchanger, and is constituted by laminating a plurality of flat radiating tubes 20 and radiating fins 21. The radiator tube 20 is composed of two molded plates 22 press-formed into an oval shape (see FIG. 8).
Are provided in a flat hollow body by joining the outer peripheral edges of each other,
The communication ports 22a are open at both ends in the longitudinal direction. Further, an inner fin 23 (see FIG. 2) formed by shaping a thin aluminum plate into a corrugated shape is inserted into the heat radiation tube 20. As shown in FIG.
Are laminated on both sides of each other, and communicate with each other through their respective communication ports 22a. Further, the heat radiating pipe 20 connected to the connecting part 4 and the connecting part 4 communicate with each other through the communication ports 171 and 172 of the connecting part 4 and the communication port 22 a of the heat radiating pipe 20. The heat radiating fins 21 are inserted into flat spaces formed between the adjacent heat radiating tubes 20 in the stacking direction, and are brazed to the outer wall surface of the heat radiating tubes 20. The cooling fan blows air to the radiator 5, and is arranged above the radiator 5 so that the blowing direction is substantially perpendicular to the radiator 5.

Next, the operation of this embodiment will be described. The refrigerant boiled by the heat generated from the heat generating element 2 is transferred to the vapor passages 9 as bubbles and rises from the vapor passages 9 to the connecting portions 4.
And flows into each heat radiation pipe 20 from one communication port 171 through one communication chamber. The vapor refrigerant flowing through each radiator tube 20 is:
The radiator tube 20 which is cooled by the cooling fan
Inner fin 2 inserted into inner wall surface of heat sink and radiator tube 20
Condensed and liquefied on the surface of 3. The refrigerant is liquefied to form droplets, and the refrigerant flows through the bottom surface of the heat radiating pipe 20 attached to the connecting portion 4 at an angle, flows into the other communication chamber of the connecting portion 4, and further flows into the other communication chamber of the connecting portion 4. Flows into the condensate passage 10 of the refrigerant tank 3 from the communication port 172 of the refrigerant tank 3. The condensate flowing down the condensate passage 10 is supplied again to the vapor passage 9 through the communication passage 16 in the cap 8. On the other hand, the latent heat of condensation released when the vapor refrigerant is condensed in the radiator tube 20 is transmitted from the radiator tube 20 to the radiating fins 21 and released into the air blown by the cooling fan.

(Effect of the First Embodiment) In this embodiment, since a large number of irregularities effective for forming bubble nuclei are formed on the inner wall surface of the vapor passage 9 of the refrigerant tank 3, bubbles are generated on the boiling surface. The heat dissipation performance can be improved by increasing the score. A comparison between the case where the inner wall surface of the steam passage 9 is roughened (in the case of the present embodiment) and the conventional case where the inner wall surface is not roughened shows that the refrigerant tank 3 to which the heating element 2 is attached as shown in FIG. 4 ~ 5
Can be reduced by about ° C. In addition, since the uneven shape effective for forming the bubble nuclei is on the order of microns, it is desirable that the particles R injected into the vapor passage 9 have a particle diameter of 100 to 1000 μm. According to the method of the present embodiment, even if the boiling surface exists inside the container (that is, inside the extruded material 7), many irregularities can be formed only by injecting the particles R into the inside of the steam passage 9, Processing can be completed easily in a short time, and the boiling surface can be roughened at low cost.

The extruded material 7 is arranged such that the opening end on the side where the particles R are injected is directed upward. This is because the degree (roughness) of the irregularities formed by the collision of the particles R is
As shown in FIGS. 5 (b) and 5 (c), the degree of the irregularity increases (rougher the surface) as it approaches the opening end on the ejection side, and the degree of the irregularity decreases as the distance from the opening end on the ejection side decreases (the surface becomes (Smoothness), it is possible to improve the heat radiation performance by improving the boiling heat transfer in the upper part in the refrigerant tank 3 by arranging the opening end on the injection side with a rougher surface upward. Further, the steam passage 9
Are formed only on the inner wall surface of the substrate due to the collision of the particles R. Although the boiling of the refrigerant can be promoted by roughening the inner wall surface of the vapor passage 9, the condensed liquid condensed by the radiator 5 flows down in the condensed liquid passage 10. It is better to suppress the boiling (foaming) of the refrigerant, and roughening the inner wall surface of the condensed liquid passage 10 has the opposite effect in terms of improving heat dissipation.

(Second Embodiment) FIG. 10 is an explanatory view for roughening the steam passage 9 of the extruded material 7. In this embodiment, as shown in FIG. 10, the injection nozzle 1 is provided for each small passage 9a of the steam passage 9.
5 shows an example in which a roughening process is performed at one time. Thus, it goes without saying that the processing time can be reduced.

(Third Embodiment) FIG. 11 is a top view of the extruded material 7. This embodiment shows an example in which a large number of fine irregularities are formed on the inner wall surface of the steam passage 9 by extrusion. As shown in FIG. 12A, the shape of the unevenness is a pit shape 24 in which the internal space is formed wide, or FIG.
A wedge shape 25 as shown in FIG. As in the present embodiment, even in the extrusion process, by forming irregularities effective for forming bubble nuclei, the number of bubbles generated on the boiling surface is increased, and the heat radiation performance can be improved. In addition, the steam passage 9 is extruded.
After the irregularities are formed on the inner wall surface, the particles R can be further sprayed to roughen the surface. In this case, since more irregularities are formed, the heat radiation performance can be further improved.

In each of the above embodiments, the steam passage 9
It is desirable that the concavo-convex shape formed on the inner wall surface be set larger as it is closer to the radiator 5. This is because the temperature of the refrigerant in the portion of the refrigerant tank 3 close to the radiator 5 becomes low and the heat is hardly absorbed, but the above configuration makes it easier to absorb heat.

[Brief description of the drawings]

FIG. 1 is a front view of a boiling cooling device.

FIG. 2 is a side view of the boiling cooling device.

FIG. 3 is a top view (a) and a front view (b) of an extruded material.

FIG. 4 is an explanatory view for roughening a steam passage of an extruded material.

FIG. 5 is a graph showing the surface roughness of the inner wall surface of the steam passage.

FIG. 6 is a plan view (a) and a top view (b) of a forming plate.

FIG. 7 is a front view (a) and a side view (b) of a separator.

FIG. 8 is a top view (a) and a plan view (b) of a plate.

FIG. 9 is a graph comparing the mounting surface temperatures of the refrigerant tanks.

FIG. 10 is an explanatory view for roughening a steam passage of an extruded material (second embodiment).

FIG. 11 is a top view of an extruded material (third embodiment).

FIG. 12 is a sectional view showing irregularities formed on an inner wall surface of a steam passage (third embodiment).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiling cooling device 2 Heating element 3 Refrigerant tank 5 Radiator 7 Extruded material (hollow body) 8 Cap (closing member) 9 Steam passage 10 Condensed liquid passage R Particle

Claims (8)

[Claims] 1. A boiling cooling device for cooling a heating element by a boiling and condensing action of a refrigerant, comprising: a refrigerant tank containing the refrigerant; and a vapor refrigerant vaporized by receiving heat of the heating element in the refrigerant tank. A radiator that flows in and releases heat of the vapor refrigerant, wherein the refrigerant tank includes a hollow body having both ends opened, and a closing member that closes one open end of the hollow body; Is a boil cooling device characterized in that particles are sprayed from the opening end into the hollow interior, and the collision of the particles forms irregularities on the inner wall surface. 2. The boiling cooling device according to claim 1, wherein the refrigerant tank is arranged with an opening end on an injection side where the particles of the hollow body are injected facing upward. 3. The hollow body is provided with a vapor passage through which a vapor refrigerant vaporized by receiving heat from the heating element rises, and a condensed liquid passage through which condensed liquid condensed and liquefied by the radiator flows down. 3. The boiling cooling device according to claim 1, wherein the unevenness is formed only on an inner wall surface of the steam passage. 4. A boiling cooling device for cooling a heating element by a boiling and condensing action of a refrigerant, comprising: a refrigerant tank containing the refrigerant; and a vapor refrigerant vaporized by receiving heat of the heating element in the refrigerant tank. A radiator that flows in and releases heat of the vapor refrigerant, wherein the refrigerant tank includes a hollow body having both ends opened, and a closing member that closes one open end of the hollow body; Is a boil cooling apparatus characterized in that fine irregularities are formed on an inner wall surface by extrusion molding. 5. The hollow body is provided with a vapor passage through which a vapor refrigerant vaporized by receiving heat from the heating element rises, and a condensate passage through which condensate condensed and liquefied by the radiator flows down. The boiling cooling device according to claim 4, wherein the irregularities are formed only on the inner wall surface of the steam passage. 6. The boiling member according to claim 5, wherein the hollow body has particles projected from the open end of the steam passage into the hollow interior, and the inner surface of the hollow body is formed by the collision of the particles. Cooling system. 7. The boiling cooling apparatus according to claim 1, wherein the particles injected into the hollow interior of the hollow body have a particle size of 100 to 1000 μm. 8. The boiling cooling device according to claim 1, wherein the irregularities are set such that the irregularities become larger as they approach the radiator.