JP5887479B2 - COOLING DEVICE, ELECTRONIC DEVICE WITH THE SAME, AND ELECTRIC CAR - Google Patents

Description

  The present invention relates to a cooling device, an electronic device equipped with the cooling device, and an electric vehicle.

  Conventionally, this type of cooling device is known to be mounted on a power conversion circuit of an electric vehicle. In an electric vehicle, an electric motor serving as a driving power source is switched by an inverter circuit that is a power conversion circuit. A plurality of semiconductor switching elements represented by power transistors are used in the inverter circuit, and a large current of several tens of amperes flows through each element. Therefore, the semiconductor switching element generates a large amount of heat, and a high-performance cooling device is necessary. Therefore, conventionally, an inverter circuit disposed in the lower part is cooled by a boiling cooling device having a refrigerant radiator and a refrigerant tank above and below (see, for example, Patent Document 1).

  Such a conventional cooling device employs a system that removes heat from the switching element by latent heat generated by contacting the semiconductor switching element and vaporizing the liquid refrigerant in the refrigerant tank. Specifically, the vaporized refrigerant rises to the radiator disposed at the upper portion, and then condenses on the wall surface in the radiator and liquefies again. Next, cooling of the liquefied refrigerant is continued by continuously repeating a cycle in which the liquefied refrigerant moves downward along the tube wall surface and again takes heat from the element and vaporizes.

  In general, the heat removed when cooling a semiconductor switching element or the like, which is a heat generating element having a high calorific value, is finally radiated from the heat dissipating part having a large area to the air as shown in FIG. It has been.

JP-A-4-139368

  However, such a heat radiating section has a problem that the condensed liquefied refrigerant stays in the horizontal pipe, whereby the refrigerant does not circulate and the above-described cycle does not rotate, and the cooling performance is remarkably deteriorated.

  Therefore, an object of the present invention is to provide a cooling device that can cool the heating element without repeating the cooling cycle and reducing the cooling performance by suppressing the retention of the liquefied refrigerant in the heat radiating section. To do.

In order to achieve this object, the present invention provides a heat receiving portion including a heat receiving plate that transfers heat from the heating element to the working fluid, a heat radiating portion that releases the heat of the working fluid, the heat receiving portion, and the heat receiving portion. A heat dissipation path connecting the heat dissipation part and a return path are configured, and the working fluid is circulated to the heat receiving part, the heat dissipation path, the heat dissipation part, the return path, and the heat receiving part to transfer heat. In the cooling device, an inflow pipe that supplies the working fluid into the heat receiving section is connected to the heat receiving section side of the return path, and a check valve is provided in a connection section between the heat receiving section and the inflow pipe, When the check valve is pushed by the pressure in the heat receiving portion, which is reduced as the working fluid is vaporized, smaller than the hydraulic head pressure of the working fluid accumulated on the check valve, the heat receiving plate is moved onto the heat receiving plate. the working fluid is supplied, the operation at the radiator portion The fluid flow path is configured to be downward slope, thereby it is to achieve the intended purpose.

According to the present invention, a heat receiving portion including a heat receiving plate that transfers heat from the heat generating element to the working fluid, a heat radiating portion that releases the heat of the working fluid, and a heat radiating path that connects the heat receiving portion and the heat radiating portion. And a return path, wherein the working fluid is circulated to the heat receiving part, the heat radiating path, the heat radiating part, the return path, and the heat receiving part to transfer heat, An inflow pipe that supplies the working fluid into the heat receiving section is connected to the heat receiving section side of the path, and a check valve is provided at a connection portion between the heat receiving section and the inflow pipe , along with vaporization of the working fluid. The working fluid is supplied onto the heat receiving plate by pushing the check valve when the reduced pressure in the heat receiving portion becomes smaller than the hydraulic head pressure of the working fluid accumulated on the check valve, The working fluid flow path in the heat radiating section has a downward slope. Since those who urchin configuration, it is possible to suppress the stagnation of liquefied working fluid at the heat radiating portion.

  That is, in the present invention, for the purpose of heat transfer from the heat receiving portion to the heat radiating portion by circulation of the working fluid serving as a refrigerant, the pipe is configured so that the flow path of the working fluid in the heat radiating portion has a downward slope. As a result, the liquefied working fluid is not retained in the piping of the heat radiating section, and the downward flow due to the gravity of the liquefied working fluid can be promoted. As a result, the cooling of the heating element is repeated continuously and stably. It is possible to provide a cooling device capable of cooling the heating element without degrading the performance.

Schematic of the electric vehicle according to the first embodiment of the present invention. Schematic showing the cooling system (A) Configuration diagram before processing of heat radiating portion of cooling device, (b) Configuration diagram after processing of heat radiating portion of cooling device (A) Configuration diagram before processing of the other heat radiating portion of the cooling device, (b) Configuration diagram during processing of the other heat radiating portion of the cooling device, (c) After processing of the other heat radiating portion of the cooling device Configuration diagram Configuration diagram of heat dissipation part of conventional cooling device

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, an electric motor (not shown) that drives an axle (not shown) of an electric vehicle 1 is connected to an inverter circuit 2 that is a power conversion device arranged in the electric vehicle 1.

  The inverter circuit 2 supplies electric power to the electric motor, and includes a plurality of semiconductor switching elements (10 in FIG. 2). The semiconductor switching elements (10 in FIG. 2) generate heat during operation.

  For this reason, in order to cool this semiconductor switching element (10 in FIG. 2), a cooling device 3 is provided. The cooling device 3 includes a heat receiving portion 4 and a heat radiating portion 5 that radiates heat absorbed by the heat receiving portion 4, and a working fluid (12 in FIG. 2) serving as a heat medium between the heat receiving portion 4 and the heat radiating portion 5. For example, by providing the heat radiation path 6 and the return path 7 for circulating water), the heat receiving section 4, the heat radiation path 6, the heat radiation section 5, the feedback path 7, and the circulation path serving as the heat receiving section 4 are configured.

  That is, in this circulation path, the working fluid (12 in FIG. 2) is a gas (water vapor in the case of water) or a liquid and a mixed state thereof, the heat receiving part 4, the heat radiation path 6, the heat radiation part 5, the return path 7, It circulates in one direction with the heat receiving part 4.

  Further, as shown in FIG. 2, the heat receiving portion 4 is in contact with the semiconductor switching element 10 to absorb heat and a heat receiving space that covers the surface of the heat receiving plate 11 and evaporates the flowing working fluid 12. And a heat-receiving plate cover 14 that forms 13.

  Furthermore, the heat receiving plate cover 14 is provided with an inlet 15 for flowing the liquefied working fluid 12 into the heat receiving space 13 and an outlet 16 for discharging the working fluid 12 from the heat receiving space 13 as a gas.

  That is, the inlet 15 and the outlet 16 are provided on the upper surface of the heat receiving plate cover 14, the return path 7 is connected to the inlet 15, and the heat dissipation path 6 is connected to the outlet 16.

  Further, an inflow pipe 19 for supplying the working fluid 12 into the heat receiving portion 4 is connected to the heat receiving portion 4 side of the return path 7 in a state of protruding into the heat receiving space 13, and the heat receiving portion 4. A check valve 18 is provided at a connection portion between the inlet 15 and the inlet pipe 19. Hereinafter, the inflow pipe 19 in the heat receiving space 13 is referred to as an introduction pipe 17.

  Further, as shown in FIG. 2, the heat dissipating unit 5 includes a heat dissipating body 8 that releases heat to the outside air, and the heat dissipating body 8 releases heat to the outside air as shown in FIG. The hairpin tube 21 has a heat radiation fin 20 formed by thinly forming aluminum in a strip shape and is laminated at a predetermined interval, and the hairpin tube 21 penetrates the heat radiation fin 20 on which the hairpin tube 21 is laminated.

  Then, heat is radiated by blowing outside air from the blower 9 to the surface of the radiating fin 20. The heat radiation from the surface of the heat radiation fin 20 can also be utilized for heating in the electric vehicle 1.

  Further, the heat dissipating unit 5 is installed by horizontally cutting the notched portions of the heat dissipating fins 20 of FIG. 3A so that both ends of the hairpin tube 21 as shown in FIG. . That is, by connecting the upper end to the heat radiation path 6 and the lower end to the return path 7, the working fluid flow path in the hairpin tube 21 is installed in a downward gradient.

  The operation of the cooling device 3 having such a configuration will be described.

  In the above configuration, when the semiconductor switching element 10 of the inverter circuit 2 starts to operate, electric power is supplied to the electric motor, and the electric vehicle 1 starts to move.

  At this time, a large current flows through the semiconductor switching element 10, and at least several percent of the total power is lost to generate a large amount of heat.

  On the other hand, the heat generated from the semiconductor switching element 10 is removed by the latent heat generated when the working fluid 12 supplied onto the heat receiving plate 11 of the heat receiving space 13 is instantly vaporized. The heat flows from the discharge port 16 to the heat radiation path 6, and heat is released from the heat radiation fins to the outside air by condensation in the heat radiation unit 5. The working fluid 12 liquefied in the heat radiating section 5 flows to the return path 7 and accumulates on the check valve 18 at the inlet 15.

  The liquefied working fluid 12 gradually increases in the return path 7, while the pressure in the heat receiving space 13 decreases conversely with the vaporization of the working fluid 12. When the pressure in the heat receiving space 13 becomes smaller than the water head pressure of the working fluid 12 accumulated on the check valve 18, the check valve 18 is pushed and operates again on the heat receiving plate 11 in the heat receiving space 13. Fluid 12 is supplied.

  In this way, the working fluid 12 circulates in the cooling device 3 to cool the semiconductor switching element 10.

  Here, the cooling mechanism in the heat receiving space 13 will be described.

  In the heat receiving space 13, the working fluid 12 from the return path 7 is dropped as droplets from the introduction pipe 17 onto the heat receiving plate 11. The dropped working fluid 12 is diffused from the gap between the end opening of the return path 7 and the heat receiving plate 11 to the outer periphery.

  At this time, the surface of the heat receiving plate 11 has a shape in which the flow path radially expands, and the working fluid 12 spreads on the heat receiving plate 11 as a thin liquid film. Since the back surface side of the heat receiving plate 11 is in contact with the semiconductor switching element 10, the working fluid 12 that has become a thin liquid film is vaporized in an instant.

  For example, when the working fluid 12 is water and the atmospheric pressure in the circulation path including the heat receiving space 13 is set lower than the atmospheric pressure, the vapor can be vaporized at a temperature lower than the boiling of water in the atmospheric pressure.

  As in the present embodiment, by setting the atmospheric pressure to −97 KPa and keeping the inside of the circulation path saturated, the boiling temperature according to the outside air temperature is determined and water can be easily vaporized. The semiconductor switching element 10 can be deprived of heat and cooled.

  Further, when the working fluid 12 is vaporized, the pressure in the heat receiving space 13 increases. However, the working fluid 12 does not flow back to the return path 7 due to the action of the check valve 18, and the discharge port 16 is surely provided. To the heat dissipation path 6.

  By operating the cooling device 3 in this manner, a regular heat receiving and releasing cycle can be performed, and the working fluid 12 can be continuously vaporized in the heat receiving space 13 to cool the semiconductor switching element 10. A large cooling effect can be obtained.

  Here, the most characteristic part of the present invention will be described.

  In general, the working fluid flows into the hairpin tube 21 in a gas-liquid mixed state in the heat radiating unit 5, and is completely liquefied immediately before the lowermost end of the hairpin tube 21, that is, immediately before the connection portion with the return path 7. Flows and accumulates on the check valve 18 at the inlet 15.

  As described above, as shown in FIG. 3B, the heat dissipating unit 5 connects the upper end to the heat dissipating path 6 and the lower end to the return path 7, thereby lowering the flow path of the working fluid in the hairpin tube 21. It is installed so as to be a slope.

  The reason for the downward slope is that when the hairpin tube 21 is horizontal, the liquefied working fluid stays in the hairpin tube 21 (particularly, in the case of water, it tends to adhere to the inner wall of the tube) and flows to the return path 7. This is particularly effective because liquefaction is promoted and stagnation tends to occur on the upper end side of the hairpin tube 21 at low outdoor temperatures in winter.

  Further, the downward gradient is from the top to the bottom, and the gradient, that is, the inclination angle, is configured to satisfy θ1 <θ2 <θ3 <θ4.

  In order to make it difficult for the liquefied working fluid to stay in the hairpin tube 21, the inclination angle may be constant and large. However, as is apparent from FIGS. 3 (a) and 3 (b), the size of the cooling device 3 is considered. In this case, since it is preferable that the gradient is small, it is preferable that the working fluid is in a gas-liquid mixed state and the amount of gas is large. In the hairpin tube 21 on the upper end side, liquefied water can easily flow due to pressure, and the inclination angle can be reduced. This is effective for reducing the increase in size of the apparatus 3.

  On the other hand, the flow of the working fluid in the hairpin tube 21 on the lower end side where the amount of gas is small is greatly influenced by gravity, and it is necessary to increase the inclination angle, so that the influence of gravity increases as it goes from top to bottom. In addition, the inclination angle is also increased in order.

  Further, in the manufacture of the hairpin tube 21 shown in FIG. 3B, as shown in the right side view of FIG. 3A, notches are provided at both ends between the holes for inserting the hairpin tubes 21 of the radiation fins. Thus, the hairpin tube 21 having the radiation fins 20 shown in FIG.

  As described above, the installation of the working fluid in the hairpin tube 21 of the heat dissipating unit 5 so as to have a downward slope can suppress the retention of the working fluid in the hairpin tube 21, and the working fluid 12 is cooled. It becomes possible to continuously circulate in the device 3, and the semiconductor switching element 10 can be cooled stably and continuously.

  In addition, since the amount of working fluid that stays in the heat radiating section 5 can be reduced, the amount of working fluid that is initially sealed in the cooling device 3 can be reduced. The effect of reducing the size and weight of the cooling device 3 can be created.

  Next, the other structure of the thermal radiation part 5 is demonstrated.

  As shown in FIG. 4A, the heat dissipating part 5 is a straight pipe having heat dissipating fins 30 that releases heat to the outside air. By applying a force in the direction of the arrow shown in the figure, the spiral shown in FIG. 4C is formed by expanding both ends of the spiral annular tube 31 up and down, that is, by connecting the upper end to the heat radiation path 6 and the lower end to the feedback path 7. The flow path of the working fluid in the annular pipe 31 is installed so as to have a downward slope.

  Further, the downward gradient is from top to bottom, and the gradient, that is, the inclination angle, is configured to satisfy θ1 <θ2 <θ3. The reason and effect of this configuration are the same as those of the hairpin tube 21 described above.

  This configuration has an effect that the height direction can be shortened as compared with the hairpin tube 21 described above.

  In the above embodiment, the cooling device 3 is applied to the electric vehicle 1. However, the cooling device 3 can also be applied to a hybrid vehicle using both electricity and gasoline, and the inverter circuit 2 that is a power converter is an electronic device. However, the cooling device 3 can also be applied to electronic equipment.

  The cooling device according to the present invention has a circulation path of the working fluid as one direction by setting a circulation path of the working fluid serving as a refrigerant as a heat receiving section, a heat radiation path, a heat radiation section, a return path, and the heat receiving section. An inflow pipe that supplies the working fluid into the heat receiving part is connected to the heat receiving part side of the return path, and a check valve is provided at a connection part between the heat receiving part and the inflow pipe, so that the working fluid is supplied in the heat receiving part. It is possible to rapidly vaporize and move the working fluid vigorously in the heat receiving plate portion. As a result, the heat transfer efficiency on the heat transfer surface can be increased and the cooling effect can be increased.

  Further, in the present invention, since the flow path of the working fluid in the heat radiating section is configured to have a downward slope, the liquefied working fluid can be prevented from staying in the heat radiating section.

  For this reason, it is useful for cooling power semiconductors used in power conversion devices as drive devices for electric vehicles, CPUs with high heat generation, and the like.

DESCRIPTION OF SYMBOLS 1 Electric vehicle 2 Inverter circuit 3 Cooling device 4 Heat receiving part 5 Heat radiating part 6 Heat radiating path 7 Return path 8 Heat radiating body 9 Blower 10 Semiconductor switching element 11 Heat receiving plate 12 Working fluid 13 Heat receiving space 14 Heat receiving plate cover 15 Inlet 16 Outlet 17 Introduction pipe 18 Check valve 19 Inflow pipe 20, 30 Radiation fin 21 Hairpin pipe 31 Annular pipe

Claims (6)

A heat receiving section having a heat receiving plate for transferring heat from the heating element to the working fluid;
A heat dissipating part for releasing the heat of the working fluid;
Consists of a heat dissipation path and a return path connecting the heat receiving section and the heat dissipation section,
A cooling device that circulates the working fluid to the heat receiving unit, the heat dissipation path, the heat dissipation unit, the return path, and the heat receiving unit to transfer heat,
An inflow pipe that supplies the working fluid into the heat receiving part is connected to the heat receiving part side of the return path, and a check valve is provided at a connection part of the heat receiving part and the inflow pipe,
When the check valve is pushed by the pressure in the heat receiving portion, which is reduced as the working fluid is vaporized, becoming smaller than the hydraulic head pressure of the working fluid accumulated on the check valve, the heat receiving plate is moved onto the heat receiving plate. The working fluid is supplied;
A cooling device, characterized in that the flow path of the working fluid in the heat radiating section is configured to have a downward slope. The cooling device according to claim 1, wherein the downward gradient of the flow path is larger on the return path side than on the heat radiation path side. The cooling device according to claim 1 or 2, wherein the heat dissipating part is constituted by a hairpin tube having heat dissipating fins. The cooling device according to claim 1 or 2, wherein the heat dissipating part comprises an annular tube having heat dissipating fins. An electronic apparatus comprising the cooling device according to claim 1. An electric vehicle comprising the cooling device according to any one of claims 1 to 4.

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