JP5891349B2 - COOLING DEVICE AND ELECTRONIC DEVICE AND ELECTRIC CAR HAVING THE SAME - Google Patents

Description

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

  Conventionally, this type of cooling device is known to be mounted on a power conversion circuit of an electronic device or 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, great heat was generated and it was necessary to cool.

  Therefore, conventionally, as in Patent Document 1, for example, a heating element such as a semiconductor switching element is cooled by a loop heat pipe including a heating unit 101, a cooler 102, a rising pipe 103, and a lowering pipe 104. .

  Hereinafter, the loop heat pipe shown in Patent Document 1 will be described with reference to FIG.

  As shown in FIG. 8, the loop heat pipe includes a loop circuit 105 that includes an ascending pipe 103 and a descending pipe 104, a heat medium 106 that is a working fluid sealed in the loop circuit 105 in a vacuum, and a loop circuit 105. The cooling unit 102 is located above the loop circuit 105, the heating unit 101 is located below the riser pipe 103, and the heat medium 106 in the loop circuit 105 is circulated through the lower part in the loop circuit 105. And a check valve 107 for limiting the direction.

  Here, when heat is generated in the semiconductor switching element brought into contact with the heating unit 101, the generated heat is transmitted to the heating unit 101, and heat is applied to the heat medium 106 circulating in the heating unit 101 to be vaporized. The circulation direction is limited by the check valve 107, and the vaporized heat medium 106 rises up the ascending pipe 103 and is led to the cooler 102 to be cooled. Here, the heat applied by the heating unit 101 is released. The heat medium 106 that has released heat from the cooler 102 descends the downcomer 104 and circulates again to the heating unit 101 via the check valve 107.

JP 61-038396 A

  In such a conventional cooling device, when the heat generated in the semiconductor switching element becomes large, it is necessary to supply the heating medium 101 to the heating unit 101 with a large amount of working fluid for cooling.

  In such a case, even if a large amount of working fluid is sealed, the circulation resistance value of the ascending pipe 103 increases, and therefore a large amount of working fluid cannot be circulated. For this reason, the amount of the heat medium 106 required for cooling cannot be supplied to the heating unit 101, and there is a problem that the cooling capacity is reduced.

  Therefore, the present invention solves the above-described conventional problems, and the heat generated in the semiconductor switching element is increased, so that it is necessary for cooling even when a large amount of working fluid needs to be supplied to the heating unit. An object of the present invention is to provide a cooling device capable of supplying an amount of working fluid and suppressing a decrease in cooling capacity.

In order to achieve this object, the cooling device of the present invention is a cooling device that circulates a working fluid and cools it by a phase change between a liquid phase and a gas phase, and contacts the heat receiving plate with heat from a heating element. A heat receiving portion that transmits the heat to the working fluid; a heat radiating portion that releases heat of the working fluid; a heat radiating path that communicates the discharge port of the heat receiving portion and the heat radiating portion; The return path is provided with a backflow prevention valve, provided with a plurality of the discharge ports, and provided with a plurality of heat radiation paths corresponding to the number of the discharge ports, to prevent the backflow. When the pressure on the upstream side of the valve becomes higher than the pressure on the downstream side, the working fluid passes through the check valve, and the working fluid is dropped as droplets on the heat receiving plate, and the dropped operation The fluid flows between the inlet of the return path and the heat receiving plate. Is diffused into the outer peripheral portion from the surface of the heat-receiving plate, there cooler, characterized in that the working fluid is spread vaporized as a thin film, thereby is to achieve the intended purpose.

According to the cooling device of the present invention, the cooling device circulates the working fluid and cools it by the phase change between the liquid phase and the gas phase, and the heat receiving unit transmits heat from the heating element to the heat receiving plate to contact the working fluid. And a heat radiating part that releases heat of the working fluid, a heat radiating path that communicates the discharge port of the heat receiving part and the heat radiating part, and a feedback path that communicates the inlet of the heat radiating part and the heat receiving part. The return path includes a backflow prevention valve, a plurality of the discharge ports, a plurality of heat radiation paths corresponding to the number of the discharge ports, and a pressure upstream of the backflow prevention valve. When the pressure becomes higher than the pressure on the side, the working fluid passes through the backflow prevention valve, the working fluid is dropped on the heat receiving plate as droplets, and the dropped working fluid is dropped in the return path Diffused from the gap between the inlet and the heat receiving plate to the outer periphery, The surface of the hot plate has a structure that the working fluid is spread vaporized as a thin film.

As a result, the working fluid is heated by the heat receiving plate at a high temperature and is instantly vaporized, and the heat from the heating element is removed as latent heat of vaporization by the working fluid, thereby enabling efficient cooling. In addition, since the circulation resistance of the working fluid in the heat dissipation path can be reduced compared to the case where a single discharge port and a single heat dissipation path are provided, the circulation amount of the working fluid can be increased. it can.

  As a result, the heat generated in the heating element increases, and even when a large amount of working fluid needs to be supplied to the heating unit, the amount of working fluid necessary for cooling can be supplied, resulting in a decrease in cooling capacity. The effect that it can suppress can be acquired.

Schematic of an electric vehicle according to an embodiment of the present invention Schematic showing a cooling device provided with two outlets and two heat dissipation paths Schematic showing a cooling device with a single outlet and a single heat dissipation path (A) The schematic perspective view which shows the heat receiving part which provided two discharge ports and two heat radiation paths, (b) The schematic upper surface which shows the heat receiving part which provided two discharge ports and two heat radiation paths Figure Schematic showing a cooling device configured to communicate with the heat dissipation part after the two heat dissipation paths merge. (A) Schematic perspective view showing a heat receiving part provided with three discharge ports and three heat dissipation paths, (b) Schematic upper surface showing a heat receiving part provided with three discharge ports and three heat dissipation paths Figure (A) The schematic perspective view which shows the heat receiving part which has arrange | positioned two discharge ports at the same angle and target position with respect to the centerline which passes the center of an inflow port, (b) Two discharge ports of an inflow port Schematic top view showing a heat receiving part arranged at the same angle and target position with respect to a center line passing through the center Schematic showing a conventional cooling device

The cooling device according to claim 1 of the present invention is a cooling device that circulates a working fluid and cools it by a phase change between a liquid phase and a gas phase, and contacts the heat receiving plate with heat from a heating element to form the working fluid. A heat receiving portion for transmitting, a heat radiating portion for releasing the heat of the working fluid, a heat radiating path communicating the discharge port of the heat receiving portion and the heat radiating portion, and a feedback path communicating the inlet of the heat radiating portion and the heat receiving portion The return path is provided with a backflow prevention valve, a plurality of the discharge ports, a plurality of heat radiation paths corresponding to the number of the discharge ports, and an upstream side of the backflow prevention valve. When the pressure becomes higher than the pressure on the downstream side, the working fluid passes through the backflow prevention valve, and the working fluid is dropped as droplets on the heat receiving plate, and the dropped working fluid is returned to the feedback Diffusion from the gap between the inlet of the path and the heat receiving plate to the outer periphery In the surface of the heat-receiving plate has a structure that the working fluid is spread vaporized as a thin film.

  Thereby, compared with the case where a single discharge port and a single heat dissipation path are provided, the circulation resistance value of the working fluid in the heat dissipation path can be reduced, thereby increasing the circulation amount of the working fluid. be able to.

  As a result, the heat generated in the heating element increases, and even when a large amount of working fluid needs to be supplied to the heating unit, the amount of working fluid necessary for cooling can be supplied, resulting in a decrease in cooling capacity. The effect that it can suppress can be acquired.

  The cooling device according to claim 2 may be configured such that a plurality of the heat radiation paths have the same vertical cross-sectional area with respect to the working fluid circulation direction.

  Thereby, since the circulating resistance value of the working fluid in the plurality of heat radiation paths can be made the same value, the amount of the working fluid in the plurality of heat radiation paths can be made the same amount. That is, the amount of the working fluid discharged from the heat receiving portion to the plurality of discharge ports can be made the same amount. Therefore, the bias of the circulating state of the working fluid in the heat receiving part can be suppressed and the working fluid can be circulated efficiently, so that the amount of circulating working fluid can be increased.

  As a result, the heat generated in the heating element increases, and even when a large amount of working fluid needs to be supplied to the heating unit, the amount of working fluid necessary for cooling can be supplied, resulting in a decrease in cooling capacity. The effect that it can suppress can be acquired.

  Moreover, the cooling device according to claim 3 may be configured such that the entire length of the plurality of heat radiation paths is the same.

  Thereby, since the circulating resistance value of the working fluid in the plurality of heat radiation paths can be made the same value, the amount of the working fluid in the plurality of heat radiation paths can be made the same amount. That is, the amount of the working fluid discharged from the heat receiving portion to the plurality of discharge ports can be made the same amount. Therefore, the bias of the circulating state of the working fluid in the heat receiving part can be suppressed and the working fluid can be circulated efficiently, so that the amount of circulating working fluid can be increased.

  As a result, the heat generated in the heating element increases, and even when a large amount of working fluid needs to be supplied to the heating unit, the amount of working fluid necessary for cooling can be supplied, resulting in a decrease in cooling capacity. The effect that it can suppress can be acquired.

  The cooling device according to claim 4, wherein the inflow port is provided in the center of the heat receiving portion, and a plurality of the discharge ports and the inflow ports all have the same distance, and the plurality of the discharge ports. May be arranged at equal intervals on the circumference centered on the inlet.

  Thereby, the circulation resistance value of the working fluid from the inflow port to the plurality of discharge ports can be made the same value in the heat receiving part. Therefore, the bias of the circulating state of the working fluid in the heat receiving part can be suppressed and the working fluid can be circulated efficiently, so that the amount of circulating working fluid can be increased.

  As a result, the heat generated in the heating element increases, and even when a large amount of working fluid needs to be supplied to the heating unit, the amount of working fluid necessary for cooling can be supplied, resulting in a decrease in cooling capacity. The effect that it can suppress can be acquired.

  Further, the cooling device according to claim 5 may be an electronic device including the cooling device according to any one of claims 1 to 4.

  Thus, the electronic device has a configuration including a cooling device that can supply the working fluid to the heat receiving portion even when the heat generated in the heating element becomes large, and has an effect of suppressing a decrease in cooling capacity. Become.

  As a result, even when the heat generated in the electronic device is increased and the amount of working fluid required for cooling is increased, the working fluid can be supplied to the heat receiving part, so that the reduction in cooling capacity can be suppressed. The effect that it is possible can be obtained.

  The cooling device according to a sixth aspect may be an electric vehicle including the cooling device according to any one of the first to fourth aspects.

  Thus, the electric vehicle has a configuration including a cooling device that can supply the working fluid to the heat receiving portion even when the heat generated in the heating element increases, and has an effect of suppressing a decrease in cooling capacity. Become.

  As a result, even when the amount of heat generated in the electric vehicle increases and the amount of working fluid required for cooling increases, the working fluid can be supplied to the heat receiving part, so that it is possible to suppress a decrease in cooling capacity. The effect that it is possible can be obtained.

  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 the 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 (9 in FIG. 2). The semiconductor switching elements (9 in FIG. 2) generate heat during operation.

  For this reason, in order to cool this semiconductor switching element (9 in FIG. 2), a cooling device 3 is provided for cooling by circulating a working fluid (11 in FIG. 2, for example, water) serving as a heat medium. .

  The cooling device 3 includes a heat receiving portion 4 that applies heat to the working fluid (for example, water in 11 of FIG. 2) and a heat radiating portion 5 that releases the applied heat, and a heat medium between the heat receiving portion 4 and the heat radiating portion 5. By providing a plurality of heat radiation paths 6 for circulating the working fluid (11 in FIG. 2, for example, water) and a return path 7, the heat receiving part 4, the plurality of heat radiation paths 6, the heat radiation part 5, and feedback A circulation path serving as the path 7 and the heat receiving unit 4 is configured.

  Further, by providing the return path 7 with a backflow prevention valve (16 in FIG. 2), in this return path 7, the working fluid (11 in FIG. 2, for example, water) is in a gaseous state (water vapor in the case of water) or liquid. In the state and the mixed state thereof, the heat receiving part 4, the plurality of heat radiation paths 6, the heat radiation part 5, the return path 7, and the heat reception part 4 circulate in one direction.

  Here, the heat radiating unit 5 is cooled and releases heat when the outside air is blown from the blower 8.

  The heat released from the surface of the heat radiating part 5 can also be used for heating the inside of the electric vehicle 1.

  As shown in FIG. 2, the heat receiving unit 4 forms a heat receiving plate 10 that contacts the semiconductor switching element 9 and absorbs heat, and a heat receiving space 12 that covers the surface of the heat receiving plate 10 and evaporates the working fluid 11 that has flowed in. And a heat receiving plate cover 13.

  Further, the heat receiving plate cover 13 has an inlet 14 through which the working fluid 11 flows into the heat receiving space 12 from the return path 7, and the number of the heat radiating paths 6 through which the working fluid 11 is discharged from the heat receiving space 12 to the plurality of heat radiating paths 6. A plurality of discharge ports 15 corresponding to the above are provided.

  Here, the return path 7 is provided with a backflow prevention valve 16 near the inlet 14.

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

  In the above configuration, when the semiconductor switching element 9 of the inverter circuit 2 starts operation, electric power is supplied to the electric motor, and the electric vehicle 1 starts to move.

  At this time, a large amount of heat is generated due to a large current flowing through the semiconductor switching element 9.

  Here, the heat generated in the semiconductor switching element 9 is transmitted to the heat receiving plate 10. The heat transmitted to the heat receiving plate 10 instantly vaporizes the liquid working fluid 11 supplied onto the heat receiving plate 10 in the heat receiving space 12 and changes it to a gas state. The working fluid 11 in a gaseous state given the latent heat of vaporization circulates from the plurality of outlets 15 to the plurality of heat radiation paths 6, is cooled by the heat radiation unit 5, is condensed, and becomes a liquid state by being converted into a liquid state. discharge.

  Subsequently, the liquid working fluid 11 that has released the latent heat of condensation circulates to the return path 7 and accumulates on the backflow prevention valve 16. The working fluid 11 in the liquid state gradually increases in the return path 7 and the head pressure increases. On the other hand, since the working fluid 11 is not supplied in the heat receiving space 12, the working fluid 11 in the gas state gradually decreases and the pressure in the heat receiving space 12 decreases.

  The pressure on the upstream side of the backflow prevention valve 16 (the sum of the pressure in the vicinity of the upstream side of the backflow prevention valve 16 and the head pressure of the working fluid 11 in the liquid state in the return path 7) is the pressure on the downstream side of the backflow prevention valve 16 ( When the pressure is higher than the pressure in the vicinity of the downstream side of the backflow prevention valve 16, the working fluid 11 passes through the backflow prevention valve 16 and is supplied again onto the heat receiving plate 10 of the heat receiving space 12.

  In this way, the working fluid 11 circulates through the cooling device 3 to cool the semiconductor switching element 9.

  Here, the cooling mechanism of the heat receiving space 12 will be described with reference to FIG.

  In the heat receiving space 12, the working fluid 11 from the return path 7 is dropped as droplets on the heat receiving plate 10. The dropped working fluid 11 is diffused from the gap between the inlet 14 of the return path 7 and the heat receiving plate 10 to the outer peripheral portion. At this time, the working fluid 11 spreads as a thin film on the surface of the heat receiving plate 10, and heat from the high temperature heat receiving plate 10 is applied to vaporize in an instant.

  Although the atmospheric pressure inside the cooling device 3 including the heat receiving space 12 varies depending on the working fluid 11 to be used, for example, when water is used as the working fluid 11, the water in the atmospheric pressure is set by setting it lower than the atmospheric pressure. It can be vaporized at a temperature lower than that of boiling. In the present embodiment, desired water is sealed in the cooling device 3 whose pressure is reduced to a substantially vacuum, and a saturated water vapor state corresponding to the outside air temperature is maintained, so that the outside temperature + a vaporization temperature of about several tens of degrees can be easily achieved. Water can be vaporized.

  Thereby, the heat from the semiconductor switching element 9 is removed to the working fluid 11 as latent heat of vaporization, and efficient cooling becomes possible.

  Further, when the working fluid 11 is vaporized, the pressure in the heat receiving space 12 increases. However, the working fluid 11 does not flow back to the return path 7 due to the action of the backflow prevention valve 16, and a plurality of exhaust gases are reliably discharged. It can be discharged from the outlet 15 to the plurality of heat radiation paths 6.

  By operating the cooling device 3 in this manner, a regular heat receiving and releasing cycle can be performed, and the working fluid 11 is continuously vaporized in the heat receiving space 12 to efficiently remove the heat from the semiconductor switching element 9. A great cooling effect can be realized.

  Next, the most characteristic part in this embodiment will be described.

  FIG. 2 shows the cooling device 3 provided with two discharge ports 15 and two heat dissipation paths 6, and FIG. 3 shows the cooling device 3 provided with a single discharge port 15 and a single heat dissipation path 6. .

  First, the case where the semiconductor switching element 9 is cooled with the cooling device 3 provided with the single discharge port 15 and the single heat radiation path 6 is demonstrated using FIG.

  As described above, the working fluid 11 in the liquid state passes through the backflow prevention valve 16, is supplied to the heat receiving unit 4, and is cooled by removing the heat generated from the semiconductor switching element 9.

  At this time, if the amount of heat generated in the semiconductor switching element 9 increases, a large amount of working fluid 11 needs to be supplied to the heat receiving space 12 for cooling. Here, even if a large amount of the working fluid 11 necessary for cooling is enclosed, the circulation flow rate also increases as the amount of generated heat increases, so that the circulation resistance value also increases, and the amount of cooling necessary. The working fluid 11 cannot be supplied to the heat receiving unit 4.

  As a result, the cooling capacity is reduced, and the heat generated from the semiconductor switching element 9 cannot be removed. In the worst case, the semiconductor switching element 9 is destroyed.

  Next, the case where the semiconductor switching element 9 is cooled by the cooling device 3 provided with the two discharge ports 15 and the two heat radiation paths 6 will be described with reference to FIG.

  As shown in FIG. 2, since the two discharge ports 15 and the two heat dissipation paths 6 are provided, compared with the case where the single discharge port 15 and the single heat dissipation path 6 are provided, The circulation resistance value when the same amount of the working fluid 11 circulates can be reduced, and the increase in the circulation resistance value accompanying the increase in the amount of generated heat can be suppressed.

  As a result, even when a large amount of the working fluid 11 is sealed, the working fluid 11 is easily supplied to the heat receiving unit 4, so that the heat generated in the semiconductor switching element 9 increases and the working fluid 11 necessary for cooling is increased. Even when the amount of the refrigerant increases, the working fluid 11 can be supplied to the heat receiving unit 4, so that the cooling capacity can be prevented from decreasing.

  Further, the vertical sectional areas of the two heat radiation paths 6 with respect to the circulation direction of the working fluid 11 indicated by the arrows in FIG.

  By adopting such a configuration, the circulation resistance value of the working fluid 11 can be made the same value in the two heat radiation paths 6, so that the amount of the working fluid 11 circulating in the two heat radiation paths 6 is the same amount. Can be. That is, the amount of the working fluid 11 discharged from the heat receiving portion 4 to the two discharge ports 15 can be made the same amount. Therefore, the bias of the circulating state of the working fluid 11 in the heat receiving unit 4 can be suppressed, and the working fluid 11 can be circulated efficiently, so that the circulation amount of the working fluid 11 can be increased.

  As a result, even when a large amount of the working fluid 11 is sealed, the working fluid 11 is easily supplied to the heat receiving unit 4, so that the heat generated in the semiconductor switching element 9 increases and the working fluid 11 necessary for cooling is increased. Even when the amount of the refrigerant increases, the working fluid 11 can be supplied to the heat receiving unit 4, so that the cooling capacity can be prevented from decreasing.

  Further, as shown in FIG. 2, the entire length of the two heat radiation paths 6 is the same length.

  By adopting such a configuration, the vertical cross-sectional areas of the two heat radiation paths 6 with respect to the circulation direction of the working fluid 11 described above are all the same area, and the working fluid 11 in the two heat radiation paths 6 is the same. The circulation resistance value of the same can be made the same value. Detailed description is omitted.

  Here, FIG. 4 shows the heat receiving section 4 provided with two discharge ports 15 and two heat radiation paths 6.

  As shown in FIG. 4, in the cooling device 3 of the present invention, the inlet 14 is provided in the center of the heat receiving portion 4, and the distances between the two outlets 15 and the inlet 14 are all the same distance. The individual outlets 15 are arranged at intervals of 180 degrees on the circumference centering on the inlet 14.

  By adopting such a configuration, the circulation resistance value of the working fluid 11 from the inlet 14 to the two outlets 15 in the heat receiving part 4 can be made the same value. The amount of the working fluid 11 discharged to the discharge port 15 can be made the same amount. Therefore, the bias of the circulating state of the working fluid 11 in the heat receiving unit 4 can be suppressed, and the working fluid 11 can be circulated efficiently, so that the circulation amount of the working fluid 11 can be increased.

  As a result, even when a large amount of the working fluid 11 is sealed, the working fluid 11 is easily supplied to the heat receiving unit 4, so that the heat generated in the semiconductor switching element 9 increases and the working fluid 11 necessary for cooling is increased. Even when the amount of the refrigerant increases, the working fluid 11 can be supplied to the heat receiving unit 4, so that the cooling capacity can be prevented from decreasing.

  Here, FIG. 5 shows the cooling device 3 configured to communicate with the heat radiating portion 5 after the two heat radiating paths 6 merge. FIG. 6 shows the heat receiving portion 4 provided with three discharge ports 15 and three heat radiation paths 6.

  In FIG. 2, the two heat radiation paths 6 are configured to communicate with the heat radiation part 5, respectively, but may be configured to communicate with the heat radiation part 5 after the two heat radiation paths 6 merge as illustrated in FIG. 5. No difference in action and effect.

  In addition, in the said embodiment, although the discharge port 15 and the heat radiation path | route 6 are demonstrated in the case of two, when it is set as 3, 4, 5, ... N and plural, As the discharge port 15 and the heat radiation path 6 increase, the value of the circulation resistance value can be further reduced, and the circulation amount of the working fluid 11 can be further increased.

  In the case where three discharge ports 15 are arranged, as shown in FIG. 6, the discharge ports 15 are arranged at intervals of 120 degrees on the circumference around the inflow port 14. Similarly, in the case where a plurality of four, five,... N are arranged, they are arranged at intervals of 90 degrees, 72 degrees,... 360 / N degrees on the circumference around the inlet 14. It becomes composition.

  In the heat receiving portion 4 provided with the two discharge ports 15 and the two heat radiation paths 6, the two discharge ports 15 are arranged on the center line passing through the center of the inflow port 14 as shown in FIG. On the other hand, even if it is a structure arranged at the same angle and at the target position, there is no difference in the operational effect.

  In the above embodiment, the cooling device 3 applied to the electric vehicle 1 has been described. However, the cooling device 3 can also be applied to an electronic device.

  The cooling device according to the present invention can supply a working fluid in an amount necessary for cooling even when a large amount of heat is generated in the semiconductor switching element and a large amount of working fluid needs to be supplied to the heating unit. Therefore, it is useful for cooling semiconductor switching elements and the like in inverter circuits of electronic devices and electric vehicles.

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 Blower 9 Semiconductor switching element 10 Heat receiving plate 11 Working fluid 12 Heat receiving space 13 Heat receiving plate cover 14 Inlet 15 Outlet 16 Backflow prevention valve

Claims (6)

A cooling device that circulates the working fluid and cools it by the phase change between the liquid phase and the gas phase, and contacts the heat receiving plate with heat from the heating element to transmit the heat to the working fluid, and releases the heat of the working fluid. And a heat radiation path that communicates the discharge port of the heat receiving part and the heat radiation part, and a feedback path that communicates the inlet of the heat radiation part and the heat receiving part. A plurality of discharge ports, a plurality of heat dissipation paths corresponding to the number of the discharge ports, and when the upstream pressure of the backflow prevention valve becomes higher than the downstream pressure The working fluid passes through the backflow prevention valve, and the working fluid is dropped as droplets on the heat receiving plate, and the dropped working fluid passes through a gap between the inlet of the return path and the heat receiving plate. Diffused to the outer periphery, the surface of the heat receiving plate, the operation Body cooling apparatus characterized by to spread vaporized as a thin film.   2. The cooling device according to claim 1, wherein vertical cross-sectional areas of the plurality of heat radiation paths with respect to the working fluid circulation direction are all the same area.   The cooling device according to claim 1 or 2, wherein the plurality of heat radiation paths have the same overall length.   The inflow port is provided at the center of the heat receiving portion, and the distance between the plurality of discharge ports and the inflow port is all the same, and the plurality of discharge ports are on the circumference centering on the inflow port. The cooling device according to any one of claims 1 to 3, wherein the cooling devices are arranged at equal intervals.   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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