JP2000156445A - Boiling cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiling cooling device where a liquid return path which is large in pressure loss can be provided in a limited space in a cooling medium tank without interfering with a heating element mounting structure such as a hole or the like. SOLUTION: A liquid return path 10 for returning a condensate liquefied by a heat radiator to a boiling space 7 is provided in a cooling medium tank, extending downward from another header connector 9 so as to lead to the lowermost part of the boiling space 7. A bent part 10a is provided as a resistor to the liquid return path 10 at its middle point so as to enhance it in path resistance. Holes 12 for fixing a heating element with a fixing member or the like are provided around the boiling space 7 in the cooling medium tank. A hole 12a located outside the liquid return path 10 is provided in a space produced by the bent part 10a of the liquid return path 10.

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 a boiling and condensing action of a refrigerant.

[0002]

2. Description of the Related Art In a boiling cooling apparatus, a refrigerant must repeatedly circulate between a heat receiving section and a heat radiating section because the refrigerant repeats boiling (evaporation) and condensation to carry out heat transport from the heat receiving section to the heat radiating section. Cannot be operated stably. Therefore, for example, the boiling cooling device described in JP-A-9-205167 has a liquid return passage for returning the condensed liquid liquefied by the radiator. This prevents interference between the refrigerant vapor boiling due to the heat of the heating element in the boiling region of the refrigerant tank and the liquid refrigerant flowing back from the radiator to the liquid return passage, so that the refrigerant flows between the heat receiving part and the heat radiation part. Can be circulated well.

[0003]

However, since the above-described refrigerant tank having the liquid return passage uses an extruded material such as aluminum, the liquid return passage must be formed only in a straight line due to its production method. Can not. In this case, if an attempt is made to secure a larger boiling space (heat receiving portion), the space for naturally forming the liquid return passage is limited. Especially when used for cooling electronic devices such as computer chips, the cooler itself is small, so if it is desired to form a liquid return passage within a predetermined size of the coolant tank, it is provided around the boiling space. There is a problem that the liquid return passage cannot be formed in a straight line because the heating element mounting structure such as a hole interferes with the liquid return passage.

When the refrigerant tank and the radiator are connected by two passages, if the pressure loss of the two passages is designed to be different from each other, the refrigerant vapor preferentially passes through the passage having a small pressure loss. Can be used as the liquid return passage. In order to increase the pressure loss of the liquid return passage, it is conceivable to reduce the passage cross-sectional area or lengthen the passage length. There is a limit to reducing the cross-sectional area, and it is also difficult to increase the passage length with a small cooler. The present invention has been made based on the above circumstances, and an object thereof is to form a liquid return passage having a large pressure loss in a limited space of a refrigerant tank and to interfere with a heating element mounting structure such as a hole. It is another object of the present invention to provide a boiling cooling device capable of providing a liquid return passage.

[0005]

[Means for Solving the Problems] (Means of Claims 1 to 3)
The refrigerant tank has a vapor outlet for guiding the refrigerant vapor boiled in the boiling space to the radiator, and a liquid return passage for returning the condensed liquid liquefied by the radiator to the boiling space, and the liquid return passage boils. A resistance portion is provided on the side of the space and increases the resistance of the passage in the liquid return passage. By providing the resistance portion, the pressure loss of the liquid return passage can be increased, so that the refrigerant vapor preferentially flows out of the vapor outlet and the condensate can flow through the liquid return passage. As the resistance portion of the liquid return passage, a bent portion can be provided in the middle of the passage, or a throttle portion having a reduced passage cross-sectional area can be provided.

In the refrigerant tank, a bent portion or a throttle portion is provided in the liquid return passage, so that a space for providing a mounting structure portion (for example, a hole) for mounting the heating element can be secured. . In other words, when the bent portion or the throttle portion is provided in the liquid return passage, it is not necessary to form the liquid return passage in a straight line. Therefore, the mounting structure portion should be provided in the space secured by providing the bent portion or the throttle portion. Can be.

[0007] (Means of claim 5) The refrigerant tank has a boiling space,
A thin container in which a vapor outlet and a liquid return passage are formed,
The thin container is configured in combination with a lid member for closing the opening surface.

(Claim 6) The refrigerant tank and the radiator are assembled by integral brazing.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a plan view of a thin container showing the internal structure of a refrigerant tank. As shown in FIG. 3, the boiling cooling device 1 according to the present embodiment cools a heating element 2 such as a computer chip mounted on a printed circuit board, and has a liquid refrigerant (for example, water, alcohol, fluorocarbon, A refrigerant tank 3 for storing CFCs and the like, and a refrigerant vapor boiled by receiving heat from the heating element 2 in the refrigerant tank 3 is supplied to an external fluid (for example, outside air).
And a radiator 4 which is liquefied by heat exchange with the radiator 4. The coolant tank 3 and the radiator 4 are integrally formed by brazing.

A) The refrigerant tank 3 is composed of a thin container 5 and a lid plate 6 formed of a metal material (eg, aluminum) having excellent heat conductivity, and is used in an upright state as shown in FIG. . a) As shown in FIG. 1, the thin container 5 has a vertically long rectangular shape in plan view, and has a flat surface on one side in the thickness direction (the back side in FIG. 1), and is used as a mounting surface for the heating element 2, and the other side. Is provided with a boiling space 7, a set of header connection portions 8, 9, a liquid return passage 10, and a refrigerant injection portion 11 described below. A plurality of holes 12 penetrating the thin container 5 in the thickness direction are provided on the outer peripheral portion of the thin container 5.

The boiling space 7 forms a space in which the liquid refrigerant boils by receiving heat from the heating element 2, and is provided over the entire central portion of the thin container 5. In the boiling space 7, a large number of prisms 13 are arranged in a grid pattern at regular intervals, and the entire boiling space 7 forms a refrigerant passage partitioned like a grid. The large number of prisms 13 provided in the boiling space 7 also function as reinforcing ribs for securing the strength of the refrigerant tank 3. The header connection portions 8 and 9 are portions where the headers 19 and 20 (described below) of the radiator 4 are connected, and spaces corresponding to the cross-sectional shapes of the headers 19 and 20 are provided. One header connection portion 8 is provided adjacent to the upper right side of the boiling space 7 and communicates with the boiling space 7 through the steam outlet 14. The other header connection portion 9 is provided on the upper left side of the boiling space 7 and communicates with the boiling space 7 through the liquid return passage 10.

The liquid return passage 10 is a passage for returning the condensed liquid liquefied by the radiator 4 to the boiling space 7, and is provided extending downward from a lower portion of the other header connection portion 9.
To the bottom. The liquid return passage 10 is provided with a bent portion 10a in the middle of the passage as a resistance portion for increasing the passage resistance. The refrigerant injection part 11 is an injection passage for injecting a refrigerant into the inside of the refrigerant tank 3 (boiling space 7), and is provided, for example, below one header connection part 8 and communicates with the boiling space 7. In addition, the boiling space 7, the header connection parts 8, 9, the liquid return passage 10, and the refrigerant injection part 1
1 and the like can be formed by cutting, electric discharge machining, forging, casting, or the like.

The holes 12 are for fixing the heating element 2 to the surface (flat surface) of the thin container 5 by a fixing member (not shown), and are provided at a plurality of locations around the boiling space 7. However, the hole 12a outside the liquid return passage 10 is provided in a space formed by the bent portion 10a of the liquid return passage 10, as shown in FIG. In other words, the bent portion 10a of the liquid return passage 10 is provided so as to avoid the hole 12a.

B) The lid plate 6 is made of, for example, a clad material in which a brazing material is integrally molded on the surface, and covers the other side of the thin container 5 entirely, and the boiling space 7 and the liquid provided in the thin container 5 are provided. The opening surface of the return passage 10 is closed. However,
Openings 15 and 16 (see FIG. 3) for inserting headers 19 and 20 are opened on both upper sides of the lid plate 6, and the openings 15 and 16 communicate with the header connection portions 8 and 9, respectively. In the lid plate 6, a round hole 17 communicating with the refrigerant injection section 11 provided in the thin container 5 is opened at a lower portion of one insertion port 15, and an injection pipe 18 is connected to the round hole 17. The injection pipe 18 is an injection port for injecting the refrigerant into the refrigerant tank 3, and the injection pipe 1
After injecting a predetermined amount of refrigerant into the refrigerant tank 3 through 8, the opening at the end of the injection pipe 18 is sealed.

B) The radiator 4 includes a set of headers (steam-side header 19 and liquid-side header 20) and a core portion (radiation tube 2).
1 and a radiation fin 22), and a duct 23
An external fluid is supplied via (see FIG. 2). a) One set of headers 19 and 20 is a vapor-side header 1 into which refrigerant vapor boiled by receiving heat of the heating element 2 in the refrigerant tank 3 flows.
9 and the liquid side header 2 into which the condensed liquid liquefied in the core portion flows.
0, each of which is composed of header plates 19a and 19b and header plates 20a and 20b (see FIG. 3).

One end of the vapor side header 19 in the longitudinal direction is inserted into the inside of the refrigerant tank 3 (one header connection portion 8) from one insertion port 15 of the cover plate 6, and the cover plate 6
Are arranged so as to extend in a substantially vertical direction with respect to. As shown in FIG. 3, the vapor side header 19 has a communication port 24 (which is connected to the vapor outlet 14) communicating with the vapor outlet 14 in the refrigerant tank 3 at an end of a header plate 19 a inserted into the refrigerant tank 3. (Substantially the same size). Further, in the header plate 19a, a plurality of long holes for inserting one end of the heat radiation tube 21 are formed at equal intervals in upper and lower two stages.

One end of the liquid side header 20 in the longitudinal direction is inserted into the inside of the refrigerant tank 3 (the other header connection portion 9) from the other insertion port 16 of the lid plate 6.
Are arranged in a state of extending substantially perpendicular to (in parallel with the steam-side header 19). The liquid-side header 20 has a liquid return passage 1 formed in a lower wall surface of an end portion inserted into the inside of the refrigerant tank 3.
A communication port (not shown) that leads to 0 is opened. Further, in the header plate 20a, a plurality of long holes for inserting the other end of the heat radiation tube 21 are formed at equal intervals in upper and lower two stages.

B) The core portion is a heat radiating portion that receives the heat of the heating element 2 and releases the heat of the refrigerant vapor that has boiled to an external fluid.
It is composed of a plurality of heat radiating tubes 21 and heat radiating fins 22 interposed between the heat radiating tubes 21. The heat radiating tubes 21 are provided in a flat shape having a small thickness with respect to the width of the outer wall surface with which the heat radiating fins 22 come in contact, and are arranged in two stages, upper and lower, between the vapor header 19 and the liquid header 20. And a plurality of heat radiating tubes 2 through the heat radiating fins 22, respectively.
1 are juxtaposed.

The heat radiating tube 21 has one end inserted into a long hole formed in the header plate 19a of the vapor side header 19 and the other end formed in the header plate 20a of the liquid side header 20. The vapor-side header 19 and the liquid-side header 20 communicate with each other by being inserted into the holes. The heat radiation fins 22 are formed by alternately bending thin metal plates (for example, aluminum plates) having excellent thermal conductivity to form a wavy shape, and are thermally joined to the outer wall surface of the heat radiation tube 21.

As shown in FIG. 2, the duct 23 is provided so as to pass through the outside of the headers 19 and 20 and surround the radiator 4. In addition, the duct 23 is provided with each header 19, 20.
Of each header 1 to such an extent that a large gap does not occur between the outer wall surfaces (outer surfaces of the header plates 19b and 20b), or substantially in contact with the outer wall surfaces of the headers 19 and 20.
9 and 20 are arranged along the outer wall surface. Duct 23
The external fluid introduced into the core portion through flows through from below to above in FIG.

Next, the operation of this embodiment will be described. The liquid refrigerant in the refrigerant tank 3 is boiled by receiving the heat of the heating element 2 and then passes through the vapor outlet 14 from the boiling space 7 to the vapor side header 19.
And flows from the steam side header 19 to each of the heat radiating tubes 21. The refrigerant vapor flowing through the heat radiating tube 21 is cooled by the external fluid introduced into the core portion through the duct 23, and condenses in the heat radiating tube 21. The condensed refrigerant becomes droplets and is pushed down to the liquid-side header 20, and then returns from the liquid-side header 20 to the boiling space 7 in the refrigerant tank 3 through the liquid return passage 10. The flow of the refrigerant in this operation is shown by arrows in FIG.

(Effects of the present embodiment) In the boiling cooling device 1 of the present embodiment, the bent portion 10a is provided in the liquid return passage 10, so that the passage resistance is increased as compared with the case where the liquid return passage 10 is formed linearly. As a result, the pressure loss of the liquid return passage 10 can be increased.
Thereby, the refrigerant vapor preferentially flows out from the vapor outlet 14, and the condensate can flow through the liquid return passage 10.
Further, by providing the bent portion 10a in the liquid return passage 10, the hole 12a can be provided in a space created by the bent portion 10a. As a result, the liquid return passage 10 can be formed without interfering with the hole 12a even with a small cooler for cooling the heating element 2 such as a computer chip.

(Second Embodiment) FIG. 5 is a plan view of a thin container 5. In the present embodiment, a modified example of the bent portion 10a provided in the liquid return passage 10 is shown. With the configuration of the present embodiment, the same effect as that of the first embodiment can be obtained.

FIG. 6 is a plan view of a thin container 5. This embodiment shows an example in which a heat insulating layer 25 is provided between the liquid return passage 10 and the boiling space 7. As shown in FIG. 6, the heat insulating layer 25 is provided between the liquid return passage 10 and the boiling space 7 in a passage shape. If the outer shape of the coolant tank 3 is small, the area of the boiling space 7 cannot be made sufficiently large as compared with the size of the heating element 2. Therefore, the liquid return passage 10 is too close to the mounting position of the heating element 2, There is a possibility that the condensed liquid in the passage 10 re-boils due to the heat transmitted from the heating element and flows back through the liquid return passage 10 against the direction of circulation of the refrigerant. In such a case, by providing the heat insulating layer 25 between the liquid return passage 10 and the boiling space 7, it is possible to prevent the condensed liquid in the liquid return passage 10 from re-boiling and flowing backward. The heat insulating layer 25
If it is made of a material with a small heat transfer coefficient, it can exhibit a heat insulating effect, so if a space like a passage is provided and the space communicates with the outside, the inside will be filled with air. A heat insulating effect can be obtained. Alternatively, if the inside of the passage-like space is evacuated, the heat insulating effect can be further increased. In this embodiment, the bent portion 1 is also provided in the liquid return passage 10.
0a is provided, and a hole 12a is provided in a space generated by providing the bent portion 10a.

(Fourth Embodiment) FIG. 7 is a plan view of a thin container 5. In this embodiment, the resistance portion of the liquid return passage 10 is
FIG. 7 shows an example in which the bent portion 10a is continuously formed. In this case, the pressure loss in the liquid return passage 10 can be increased as compared with the first embodiment.

(Fifth Embodiment) FIG. 8 is a plan view of a thin container 5. In this embodiment, the resistance portion of the liquid return passage 10 is
As shown in FIG. 8, the throttle section 10 having a reduced passage cross-sectional area
This shows an example in which b is provided continuously. Also in this case, the pressure loss of the liquid return passage 10 can be made larger than in the first embodiment.

[Brief description of the drawings]

FIG. 1 is a plan view of a thin container (first embodiment).

FIG. 2 is a perspective view of a boiling cooling device.

FIG. 3 is an exploded perspective view of the boiling cooling device.

FIG. 4 is a perspective view of a boiling cooling device showing a flow of a refrigerant.

FIG. 5 is a plan view of a thin container (second embodiment).

FIG. 6 is a plan view of a thin container (third embodiment).

FIG. 7 is a plan view of a thin container (fourth embodiment).

FIG. 8 is a plan view of a thin container (fifth embodiment).

[Description of Signs] 1 Boiling cooling device 2 Heating element 3 Refrigerant tank 4 Radiator 5 Thin container 6 Lid plate (Lid member) 7 Boiling space 10 Liquid return passage 10a Bent part (resistance part) 10b Narrow part (resistance part) 12a Hole 14 Steam outlet

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koji Tanaka 1-1-1, Showa-cho, Kariya-shi, Aichi Pref. (72) Inventor Akihiro Maeda 1-1 1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 5F036 AA01 BA08 BB44 BB56 BC03

Claims (6)

[Claims] A refrigerant tank having a boiling space in which a liquid refrigerant is stored and in which the liquid refrigerant boils by receiving heat from a heating element, and a refrigerant vapor flowing from the refrigerant tank is exchanged with an external fluid by heat exchange. A radiator that liquefies, and wherein the refrigerant tank has a vapor outlet for guiding refrigerant vapor boiling in the boiling space to the radiator, and a condensate liquefied by the radiator. A liquid return passage for returning to the boiling space,
The liquid cooling passage is provided on a side of the boiling space, and a resistance portion for increasing a passage resistance is provided in the liquid return passage. 2. The liquid return passage has a bent portion as the resistance portion in the middle of the passage.
The boiling cooling device described in 1. 3. The boiling cooling device according to claim 1, wherein the liquid return passage has a throttle portion having a reduced passage cross-sectional area as the resistance portion. 4. The refrigerant tank is characterized in that a space for providing a mounting structure for mounting the heating element is secured by providing the bent portion or the throttle portion in the liquid return passage. The boiling cooling device according to claim 2 or 3. 5. The refrigerant tank is constituted by combining a thin container in which the boiling space, the vapor outlet, and the liquid return passage are formed, and a lid member for closing an opening surface of the thin container. The boiling cooling device according to claim 1, wherein: 6. The refrigerant tank and the radiator are assembled by integral brazing.
The boiling cooling device according to any one of Items 1 to 5.