JP2000022377A - Boiling cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiling cooler for obtaining a stable heat radiating performance by reducing a liquid level change occurring at the time of traveling on a sloping road. SOLUTION: A hollow container of a refrigerant tank is, for example, an extrusion molding which is provided in a flat shape having a thickness thinner than a lateral width. The boiling cooler 1 is carried at a front portion of a vehicle (electric vehicle) for receiving a traveling wind. In the cooler 1, a surface of the tank (hollow container) having a heater 2 mounted therein is disposed in a longitudinal direction of the vehicle. In this case, a liquid level change in the tank occurring at the time for the vehicle to travel on a sloping road can be reduced as compared with the case that the surface of the tank is disposed toward a vehicle lateral direction. In other words, a difference between high and low levels of the liquid level position in both opposed inner walls of the tank in a thickness direction can be reduced. Thus, since a portion where a liquid refrigerant does not exist at the mounting surface of the heater 2 can be reduced, stable heat radiating performance can be obtained even at the time of traveling on the sloping road.

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 such as an IGBT module used in an inverter circuit of an electric vehicle.

[0002]

2. Description of the Related Art Conventionally, there has been known a boiling cooling apparatus for cooling a heating element by heat transfer by repeating boiling and condensation of a refrigerant. In this boiling cooling device, an expensive refrigerant such as fluorocarbon is generally used, so that the cost increases if the amount of the refrigerant sealed inside increases. Therefore, as shown in, for example, JP-A-8-204075, the thickness of the refrigerant tank is reduced to reduce the amount of refrigerant enclosed therein. Further, since this boiling cooling device is relatively small and can obtain high heat radiation performance, it is considered to be used as a cooling device for a semiconductor element used in an inverter of an electric vehicle.

[0003]

However, when the boiling cooling device having the thinned refrigerant tank is mounted on an electric vehicle as described above, the following problems occur. For example, when the boiling cooling device 100 is mounted on the electric vehicle EV as shown in FIG.
0 is arranged in the vehicle width direction), there is no problem when traveling on flat ground, but when traveling on a slope, the liquid level in the refrigerant tank 110 is greatly inclined. In this case, a portion where the liquid refrigerant does not exist is formed on the mounting surface of the heating element 200, so that the temperature of the portion rapidly rises. Considering this liquid level fluctuation, it is conceivable that a large amount of the refrigerant is sealed in advance, but the increase in the liquid refrigerant increases the cost. Further, when the liquid surface reaches the core portion 120 of the radiator, that portion does not function as the core portion 120, and thus a problem that the heat radiation performance is reduced occurs. 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 boiling cooling device capable of obtaining a stable heat radiation performance by reducing a liquid level fluctuation that occurs during traveling on a slope.

[0004]

The refrigerant tank is provided in a flat shape having a thickness smaller than the width of the surface on which the heating element is mounted, and the surface on which the heating element is mounted is mounted on the vehicle. It is arranged facing forward and backward. in this case,
Fluid level fluctuations in the refrigerant tank that occur when the vehicle travels on a slope can be reduced as compared to a case where the surface of the refrigerant tank is oriented in the vehicle width direction. That is, the height difference between the liquid surface positions on both inner wall surfaces facing the thickness direction of the refrigerant tank can be reduced. Thereby, since the portion where the liquid refrigerant does not exist on the mounting surface of the heating element can be reduced, stable heat radiation performance can be obtained even when traveling on a slope.

[0005] (Claim 2) The refrigerant tank is installed in a posture inclined toward the vehicle front side by a predetermined angle. When an electric vehicle travels on a slope, more power is required when traveling uphill than when traveling downhill. Therefore, in order to achieve the maximum heat dissipation performance with a smaller amount of refrigerant when traveling uphill, which requires more output, the refrigerant tank is installed inclining in front of the vehicle in advance, and heat is generated during operation when traveling uphill. It is advisable to enclose a minimum amount of refrigerant in which the body mounting part is immersed in the liquid. In this case, the liquid level may penetrate into the heat radiation core during traveling on level ground, and the heat radiation performance may be reduced. However, there is no problem because the output is suppressed as compared with traveling uphill.

(Means of Claim 3) In the refrigerant tank, a first heating element having a small calorific value is attached to one of two surfaces facing each other in the thickness direction, and a first heating element having a large calorific value is attached to the other surface. The two heating elements are mounted, and one surface is directed toward the vehicle front side, and the other surface is disposed toward the vehicle rear side. When such a thin refrigerant tank is tilted or used in a horizontal state, the boiling steam rises, so that the heat transfer coefficient decreases on the upper surface side of the refrigerant tank and the heat radiation performance decreases. . Since the vehicle needs more power when traveling uphill than when traveling downhill, the amount of heat generated on the upper surface side of the refrigerant tank, that is, one surface that is the front side of the vehicle, when the vehicle travels uphill. It is more effective to attach a first heating element having a small heat generation and to attach a second heating element having a large amount of heat generation to the surface on the lower surface side of the refrigerant tank, that is, the other surface on the vehicle rear side.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a view showing a state in which a boiling cooling device 1 is mounted on a vehicle. The boiling cooling device 1 cools the heating element 2 by utilizing the boiling and condensation actions of the refrigerant. As shown in FIGS. 2 and 3, a refrigerant tank 3 for storing a liquid refrigerant therein, and a refrigerant tank 3 And a radiator 4 provided on the upper part of the radiator. The heating element 2 is an IGBT module that forms an inverter circuit of the electric vehicle EV, and is fixed to both surfaces of the refrigerant tank 3 by being tightened with bolts 5.

The refrigerant tank 3 comprises a hollow container 6 formed of a metal material having excellent thermal conductivity such as aluminum, and an end tank 7 covered on the lower end of the hollow container 6. Liquid return passage 9 and reflux passage 10
Are formed. The hollow container 6 is, for example, an extruded product and is provided in a flat shape having a small thickness with respect to the lateral width as shown in FIG.
A pair of support portions 6a extending in the vertical direction の of (b) and a plurality of partition walls 6b are provided. End tank 7
Is made of, for example, the same aluminum as the hollow container 6, and its shape is shown in FIG. 5 (a) is a top view, (b) is a side view, and (c) is an AA sectional view. The end tank 7 is joined to the lower end of the hollow container 6 by brazing or the like, and closes the lower end of the hollow container 6. However, a space is secured inside the end tank 7 between the lower end surface of the hollow container 6 as shown in FIG.

The refrigerant chamber 8 is formed between a pair of columns 6a provided near the left and right sides of the hollow container 6, and the interior is partitioned into a passage by a plurality of partition walls 6b. The refrigerant chamber 8 is configured such that the liquid refrigerant stored therein has a heating element 2.
To form a boiling region that boils due to the heat of the liquid. The liquid return passage 9 is a passage through which the condensed liquid condensed by the radiator 4 flows, and is formed outside the both support portions 6a. The recirculation passage 10 is a passage for supplying the condensed liquid flowing into the liquid return passage 9 to the refrigerant chamber 8 and is formed by the inner space of the end tank 7. 8 is communicated.

The radiator 4 includes a core 11 and an upper tank 1
2 and a lower tank 13.
The refrigerant flow control plate 14 is installed inside the. Core part 1
Reference numeral 1 denotes a heat radiating unit of the present invention that condenses and liquefies refrigerant vapor that has been boiled by receiving heat from the heating element 2 by heat exchange with an external fluid (for example, air), and includes a plurality of heat radiating tubes 15 and radiating fins 16. The heat radiation tubes 15 are arranged alternately and used in a state in which the heat radiation tubes 15 are set up vertically. Heat radiation tube 15
For example, a flat tube made of aluminum is used. An inner fin (not shown) may be inserted into the heat radiation tube 15. The radiating fins 16 are corrugated fins formed by alternately bending thin metal plates (for example, aluminum plates) having excellent thermal conductivity into a corrugated shape, and are joined to the outer wall surface of the radiating tube 15 by brazing or the like.

The upper tank 12 is formed by combining an aluminum core plate 17 and a tank plate 18, for example, and is connected to the upper end of each heat radiation tube 15. 6 (a) is a plan view, (b) is a side view, and FIG. 7 (a) is a top view, (b) is a side view, and (c) is a shape of the core plate 17 and the tank plate 18, respectively. B-
It is shown in section B of FIG. The core plate 17 has a number of long holes 17a into which the ends of the heat radiation tubes 15 are inserted. The lower tank 13 is configured by combining an aluminum core plate 19 and a tank plate 20, for example, and is connected to the lower end of each heat radiation tube 15. FIGS. 8A and 8B show the shapes of the core plate 19 and the tank plate 20, respectively.
{(A) is a side view, (b) is a top view, and (c) is a CC cross-sectional view}. The core plate 19 has the same shape as the core plate 17 of the upper tank 12,
Are formed with a large number of long holes 19a into which the end portions are inserted.
The tank plate 20 has an elongated hole 20a into which the upper end of the refrigerant tank 3 (hollow container 6) is inserted.

The refrigerant flow control plate 14 reduces interference between the refrigerant vapor boiled in the refrigerant chamber 8 and the condensed liquid cooled and liquefied in the core portion 11, and as shown in FIG.
And is disposed so as to cover the upper side of the refrigerant chamber 8 from both sides. Also, the refrigerant flow control plate 14
Is installed in an inclined state so that the condensed liquid dropped on the upper surface thereof flows into the liquid return passage 9. As shown in FIG. 1, the boiling cooling device 1 of the present embodiment is mounted on a front part of a vehicle (electric vehicle EV) that receives a traveling wind and has a refrigerant tank 3 (hollow container 6) to which a heating element 2 is attached. The surface is arranged facing the front-back direction of the vehicle.

Next, the operation of this embodiment will be described. The heat generated from the heating element 2 is transmitted to the liquid refrigerant stored in the refrigerant chamber 8 through the wall surface of the refrigerant tank 3 (hollow container 6), and the liquid refrigerant boils. The boiling refrigerant turns into vapor and becomes a refrigerant chamber 8.
And flows from the refrigerant chamber 8 through the lower tank 13 to each heat radiation tube 15 of the core portion 11. The refrigerant vapor flowing into the heat radiating tube 15 is cooled by heat exchange with the outside air when flowing through the heat radiating tube 15, releases latent heat, and condenses on the inner wall surface of the heat radiating tube 15. The latent heat released when the refrigerant vapor condenses is transmitted from the wall surface of each heat radiation tube 15 to the heat radiation fins 16,
It is released to the outside air through 6. On the other hand, the heat radiation tube 15
The condensed liquid condensed into liquid droplets inside the heat radiation tube 15
The water flows downward along the inner wall surface of the heat sink, drops from the heat radiation tube 15 and returns to the refrigerant tank 3.

(Effects of the present embodiment) In the boiling cooling apparatus 1 of the present embodiment, the thickness of the refrigerant tank 3 is reduced, and the surface of the refrigerant tank 3 (hollow container 6) to which the heating element 2 is attached is mounted on a vehicle (electric vehicle EV). ). In this case, when the surface of the refrigerant tank 3 is arranged facing the vehicle width direction (FIG. 13).
), The liquid level fluctuation in the refrigerant tank 3 that occurs when the vehicle travels on a slope can be reduced. That is, as shown in FIG. 10, the height difference between the liquid surface positions on both inner wall surfaces facing the thickness direction of the refrigerant tank 3 can be reduced. Thereby, the portion where the liquid refrigerant does not exist on the mounting surface of the heating element 2 can be reduced, so that stable heat radiation performance can be obtained even when traveling on a slope.

(Second Embodiment) FIG. 11 is a view showing a state in which the boiling cooling device 1 is mounted on a vehicle. In this embodiment, as shown in FIG. 11, the surface of the refrigerant tank 3 (hollow container 6) is arranged in the front-rear direction of the vehicle, and the entire evaporative cooling device 1 is inclined toward the vehicle front side by a predetermined angle α. This is an example of installation. When a vehicle travels on a slope, more power is required when traveling uphill than when traveling downhill. Therefore, in order to exhibit the maximum heat radiation performance with a smaller amount of refrigerant when traveling uphill, the refrigerant tank 3 is previously installed inclined to the front side of the vehicle, and the mounting portion of the heating element 2 is operated when traveling uphill. It is advisable to enclose a refrigerant that is immersed in the liquid. However,
The liquid level may partially enter the heat radiation core portion 11 when traveling on level ground and the heat radiation performance may be degraded, but there is no problem because the output is suppressed as compared with when traveling uphill. Thereby, the refrigerant can be used more efficiently, and the cost can be reduced.

(Third Embodiment) FIG. 12 is a side view of the boiling cooling device 1. This embodiment shows an example in which a first heating element 2A and a second heating element 2B having different heating values are cooled by one boiling cooling device 1. As described in the second embodiment, when the vehicle travels uphill, a higher output is required than when traveling uphill. That is, the first heating element 2 having a small heat value is provided on one surface 3a on the front side of the vehicle.
It is more effective to attach A and attach the second heating element 2B having a large calorific value to the lower surface of the refrigerant tank 3, that is, the other surface 3b which is the rear side of the vehicle. This is because when such a thin refrigerant tank 3 is tilted or used in a horizontal state, the boiling steam rises and the air bubble ratio increases on the upper surface side of the refrigerant tank 3. This is because the heat transfer coefficient is lower on the upper surface side of the upper surface 3 and the boiling heat transfer performance on the upper surface side of the refrigerant tank 3 is lower.

(Modification) In the above-described embodiment, the case where the boiling cooling device 1 is mounted on the electric vehicle EV is exemplified. If the surface of the coolant tank 3 on which the heating element 2 is mounted is oriented, the same effect as in the present embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a boiling cooling device is mounted on a vehicle (first embodiment).

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

FIG. 3 is a side view of the boiling cooling device.

FIG. 4 is a top view (a) and a side view (b) of the hollow container.

FIG. 5 is a drawing showing a shape of an end tank.

FIG. 6 is a view showing a shape of a core plate of an upper tank.

FIG. 7 is a drawing showing a shape of a tank plate of an upper tank.

FIG. 8 is a view showing a shape of a core plate of a lower tank.

FIG. 9 is a drawing showing a shape of a tank plate of a lower tank.

FIG. 10 is a side view of the boiling cooling device for explaining the operation of the present embodiment.

FIG. 11 is a view showing a state in which a boiling cooling device is mounted on a vehicle (second embodiment).

FIG. 12 is a side view of a boiling cooling device (third embodiment).

FIG. 13 is a diagram showing a state in which the boiling cooling device is mounted on a vehicle.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 boiling cooling device 2 heating element 2A first heating element 2B second heating element 3 refrigerant tank 3a one surface of refrigerant tank 3b other surface of refrigerant tank 4 radiator EV electric vehicle (vehicle)

Claims (3)

[Claims] 1. A boiling cooling device mounted on a vehicle for cooling a heating element used in the vehicle, comprising: a refrigerant tank having a surface on which the heating element is mounted and storing a liquid refrigerant therein; A radiator for condensing and liquefying the refrigerant vapor boiling by receiving heat from the heating element in the tank by exchanging heat with an external fluid, wherein the refrigerant tank has a thickness width with respect to a lateral width of a surface on which the heating element is mounted. Is provided in a thin flat shape, and the surface to which the heating element is attached is arranged in the front-rear direction of the vehicle. 2. The vehicle according to claim 1, wherein the vehicle is an electric vehicle that is driven by an electric motor, the heating element is an inverter circuit that controls the number of revolutions of the electric motor, and the refrigerant tank is directed forward by a predetermined angle. The boiling cooling device according to claim 1, wherein the boiling cooling device is installed in an inclined posture. 3. The refrigerant tank has a first heating element having a small calorific value attached to one of two surfaces opposed in a thickness direction, and a second heating element having a large calorific value on the other surface. 3. The boiling cooling device according to claim 1, wherein the cooling device is attached, and the one surface is arranged toward the front of the vehicle and the other surface is arranged toward the rear of the vehicle.