Cooling device

Abstract

[Problem] To achieve both simplification of a device and high cooling efficiency of insulating oil that has received heat. [Solution] This cooling device cools a power semiconductor apparatus. The cooling device includes: a tank which accommodates the power semiconductor apparatus; insulating oil; and a refrigerant liquid having a boiling point temperature lower than the boiling point temperature of the insulating oil and having a specific gravity greater than the specific gravity of the insulating oil. The insulating oil and the refrigerant liquid are stored in a mixed state in the tank to cool the power semiconductor apparatus.

Description

[Technical Field]

[0001] The present invention relates to a cooling device. [Background technology]

[0002] Patent Document 1 discloses a cooling device in which a semiconductor stack is immersed in insulating oil and housed in an oil-filled tank, while a working fluid is sealed in heat pipe-type radiators on both sides of the semiconductor element, and cooling is performed by utilizing the boiling and condensation cycle of the sealed working fluid. In this cooling device, the insulating oil and working fluid are kept immiscible, and the insulating oil, which has risen in temperature due to heat received from the radiators, is cooled by natural convection within the oil-filled tank or forced convection using a pump, and then dissipates heat into the atmosphere through a radiator attached to the tank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-97338 Summary of the Invention [Problem to be solved by the invention]

[0004] When the heated insulating oil is subjected to natural convection, the cooling device can be simplified compared to when forced convection is used, but it is difficult to achieve high cooling efficiency compared to when forced convection is used. Conversely, when the heated insulating oil is subjected to forced convection, high cooling efficiency can be achieved compared to when natural convection is used, but an additional device such as a pump is required to force the insulating oil to be convected, which may hinder simplification of the cooling device.

[0005] The present invention has been made in view of the above problems, and aims to achieve both simplification of the device and high cooling efficiency of heated insulating oil. [Means for solving the problem]

[0006] A cooling device according to one aspect of the present invention is a cooling device for cooling power semiconductor devices, comprising a tank for accommodating the power semiconductor devices, insulating oil, and a refrigerant liquid having a boiling point lower than that of the insulating oil and a specific gravity higher than that of the insulating oil. The insulating oil and the refrigerant liquid are stored in a mixed state in the tank and cool the power semiconductor devices. [Effects of the Invention]

[0007] According to this aspect, the insulating oil and refrigerant liquid stored in a mixed state in the tank tend to exist at different vertical positions due to their different specific gravities. As a result, the refrigerant liquid, which has a higher specific gravity, is located below the insulating oil. Therefore, by performing cooling with the refrigerant liquid through vaporization heat without adding a special device for forced convection, the vaporized refrigerant liquid can agitate the insulating oil above, thereby forcing the heated insulating oil to convect. This allows for both simplified equipment and high cooling efficiency for the heated insulating oil. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of the cooling device. [Figure 2] FIG. 2 is a diagram showing the cooling device when the electric circuit is in operation. [Figure 3] FIG. 3 is a diagram showing a first modified example of the electric circuit and the cooling device. [Figure 4] FIG. 4 is a diagram showing a second modified example of the electric circuit and the cooling device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] FIG. 1 is a schematic diagram of a cooling device 100. FIG. 1 shows a static state in which the electric circuit 50 is inactive and at ambient temperature. The ambient temperature is the outside air temperature or atmospheric temperature, for example, normal temperature. The up-down direction in FIG. 1 corresponds to the vertical direction (height direction).

[0011] The cooling device 100 cools the electric circuit 50. The electric circuit 50 is, for example, an inverter (an electric circuit that functions as an inverter) and corresponds to a power semiconductor device. The electric circuit 50 has a first substrate 51, a second substrate 52, and a circuit section 55. The first substrate 51 and the second substrate 52 are printed circuit boards, and the first substrate 51 is stacked on the second substrate 52. The circuit section 55 is mounted on the first substrate 51 and the second substrate 52, and is electrically connected to the first substrate 51 and the second substrate 52 by connecting to the circuit patterns of the first substrate 51 and the second substrate 52.

[0012] The circuit section 55 has a semiconductor element 55a, wires 55b, a lead frame 55c, and a capacitor 55d. The semiconductor element 55a, wires 55b, and lead frame 55c are mounted on the first substrate 51, and the capacitor 55d is mounted on the second substrate 52. The semiconductor element 55a is a power element, such as an IGBT or a power MOSFET, or other switching element. A plurality of semiconductor elements 55a are provided, and in this embodiment, they are arranged in two rows along the depth direction of FIG. 1 (a direction perpendicular to the plane of FIG. 1). However, the arrangement of the plurality of semiconductor elements 55a is not necessarily limited to this.

[0013] The semiconductor element 55a is electrically connected to the lead frame 55c via the wires 55b. The semiconductor element 55a is sealed with a mold resin, and heat from the semiconductor element 55a is dissipated via the mold resin. Heat from the semiconductor element 55a can also be dissipated via the lead frame 55c. The semiconductor element 55a is provided on the lower side (back side) of the second substrate 52 together with the wires 55b and the lead frame 55c, and the capacitor 55d is provided on the upper side (front side) of the second substrate 52.

[0014] The semiconductor element 55a and the capacitor 55d are examples of multiple electronic components included in the electric circuit 50, and the semiconductor element 55a and the capacitor 55d have different heat generation densities. The electric circuit 50 may include electronic components other than the semiconductor element 55a and the capacitor 55d. In this embodiment, the capacitor 55d is an example of an electronic component other than the semiconductor element 55a among the multiple electronic components, and represents an electronic component other than the semiconductor element 55a. The heat generation density of the semiconductor element 55a is relatively higher than that of the capacitor 55d, and the semiconductor element 55a and the capacitor 55d correspond to multiple electronic components with different heat generation densities.

[0015] The cooling device 100 has a tank 10 and a sub-tank 20. The tank 10 houses an electric circuit 50. A boss 10a is provided on the inner surface of the side wall of the tank 10, and a second substrate 52 is fixed to the boss 10a. The second substrate 52 divides the interior of the tank 10 into an upper space and a lower space. A plurality of through holes 52a are formed in the second substrate 52, and the upper space and the lower space in the tank 10 communicate with each other via the plurality of through holes 52a. The plurality of through holes 52a can be provided in positions that do not overlap with the first substrate 51 when viewed in the vertical direction, for example.

[0016] The tank 10 has a first housing portion 11, a second housing portion 12, and a sealing member 13. The first housing portion 11 and the second housing portion 12 are both box-shaped with one side open. The first housing portion 11 and the second housing portion 12 are joined by bolts with the mating surfaces of the open ends aligned via the sealing member 13. The first housing portion 11 is disposed on the second housing portion 12, and the boss 10a is provided on the second housing portion 12.

[0017] The tank 10 stores a mixture of insulating oil OL and refrigerant liquid LQ. A mixed state refers to a state in which they are mixed and not isolated from each other in the same space, and includes cases in which they are separated according to their specific gravity in a static state. The insulating oil OL is a hydrocarbon oil, and for example, the same oil as that used for cooling and lubrication in continuously variable transmissions is used. The refrigerant liquid LQ is a fluorine-based refrigerant (a fluorine-based inert liquid), and perfluorocarbon (PFC) is used as the refrigerant liquid LQ, for example. The refrigerant liquid LQ, which is a fluorine-based refrigerant, has a higher specific gravity than the insulating oil OL. For this reason, when the insulating oil OL and refrigerant liquid LQ are stored in a mixed state in the tank 10, the insulating oil OL will be present on the upper side of the tank 10, and the refrigerant liquid LQ will be present on the lower side.

[0018] The amount of refrigerant liquid LQ stored in the tank 10 is smaller than the capacity of the second casing portion 12. For this reason, in a static state, the refrigerant liquid LQ accumulates at the bottom of the tank 10 inside the second casing portion 12. The remaining space inside the tank 10 other than the space occupied by the refrigerant liquid LQ is filled with insulating oil OL. For this reason, insulating oil OL is present at the joining position in the height direction between the first casing portion 11 and the second casing portion 12.

[0019] The sealing member 13 seals between the first housing portion 11 and the second housing portion 12, which are joined together. The sealing member 13 is provided in a range in the height direction where the insulating oil OL is stored according to its specific gravity, and prevents leakage of the insulating oil OL. The sealing member 13 can be formed of, for example, a gasket.

[0020] The tank 10 has a coolant passage 10b and a through-hole 10c. The coolant passage 10b is formed inside the upper wall of the tank 10, which is formed by the first housing portion 11. A coolant flows through the coolant passage 10b, and the coolant receives heat from the insulating oil OL and refrigerant liquid LQ in the tank 10, thereby cooling the insulating oil OL and refrigerant liquid LQ. The through-hole 10c penetrates the side wall of the tank 10, which is formed by the first housing portion 11. Therefore, the through-hole 10c is provided within a range in the height direction where the insulating oil OL is stored according to its specific gravity (a range in the height direction where the insulating oil OL exists in a static state). The through-hole 10c extends horizontally and penetrates the side wall of the tank 10.

[0021] The tank 10 further includes a shielding plate 14 and a shielding plate 15. The shielding plate 14 and the shielding plate 15 are provided on the inner surface of the side wall of the tank 10 in which the through hole 10c is provided. The shielding plate 14 is provided at the lower periphery of the opening of the through hole 10c into the tank 10, and the shielding plate 15 is provided at the upper periphery of the opening. The shielding plate 14 extends obliquely upward along the extension direction of the through hole 10c so that the farther it is from the through hole 10c, the higher it is positioned. The shielding plate 15 extends obliquely downward along the extension direction of the through hole 10c so that the farther it is from the through hole 10c, the lower it is positioned. A gap is formed between the tip of the shielding plate 14 and the tip of the shielding plate 15. Therefore, the communication between the inside of the tank 10 and the through hole 10c is not obstructed by the shielding plate 14 and the shielding plate 15.

[0022] Each of the shielding plates 14 and 15 may have, for example, a modified L-shape in cross section with an angle greater than a right angle, and may be provided by fastening one plate-like portion to the inner surface of the side wall of the tank 10 with bolts or the like as a fixing portion. The shielding plates 14 and 15 may be provided over at least the range in which the through hole 10c is provided in the front-rear direction of Fig. 1. Instead of the shielding plates 14 and 15, for example, a tapered tubular member may be provided that tapers in the extension direction of the through hole 10c as it gets further away from the through hole 10c.

[0023] The subtank 20 is provided in the tank 10. The subtank 20 has a tank portion 21 and a connection portion 22. The tank portion 21 has a cylindrical shape. The tank portion 21 extends vertically and is open at the top end. The connection portion 22 has a pipe shape and extends horizontally. The connection portion 22 has, for example, a flange at the open end as a fixing portion, and the subtank 20 is fixed to the tank 10 by bolting the flange to the side wall of the tank 10.

[0024] The connecting part 22 has a base end radially connected to the lower part of the tank part 21 and opens into the tank part 21, and its open end connects to the through-hole 10c. Therefore, the insulating oil OL stored so as to fill the tank 10 fills the through-hole 10c and the connecting part 22, as well as part of the tank part 21. A seal member can be provided between the connecting part 22 and the side wall of the tank 10 to prevent leakage of the insulating oil OL.

[0025] The sub-tank 20 further has an air chamber AR. The air chamber AR is formed directly above the insulating oil OL inside the tank portion 21. The air chamber AR communicates with the inside of the tank portion 21 via a communication passage C. The communication passage C is formed by the portion of the tank portion 21 filled with the insulating oil OL, the connection portion 22, and the through-hole 10c.

[0026] The subtank 20 further includes a breather cap 23. The breather cap 23 is attached to the upper end of the tank portion 21. The breather cap 23 has a main body portion 23a and an umbrella portion 23b. The main body portion 23a has a cylindrical shape, and a thread is formed on the outer periphery of one end of the main body portion 23a. The main body portion 23a is screwed onto the thread formed on the inner periphery of the upper end of the tank portion 21. The main body portion 23a is screwed until the flange portion on the outer periphery abuts against the tank portion 21, thereby fixing the breather cap 23 to the tank portion 21.

[0027] The umbrella portion 23b is provided at the other end of the main body portion 23a. The umbrella portion 23b has a cylindrical shape with a bottom, and covers the main body portion 23a from above to prevent water from entering from the outside. A gap is formed in the circumferential direction between the main body portion 23a and the umbrella portion 23b, and this gap is open downward to the outside air. A communication hole that connects the inside and outside is formed in the peripheral wall at the other end of the main body portion 23a. Therefore, the breather cap 23 communicates between the air chamber AR and the outside air outside the subtank 20 via the communication hole and the gap.

[0028] A labyrinth flow path L is formed within the main body portion 23a. The labyrinth flow path L allows air to pass through but prevents the insulating oil OL from passing through. Each wall portion forming the labyrinth flow path L may be inclined, for example, so that the tip end is positioned lower, thereby encouraging the insulating oil OL to fall under its own weight. The breather cap 23 corresponds to an air breather mechanism.

[0029] In a static state, the refrigerant liquid LQ has a liquid level height H, and the second substrate 52 is disposed so that the liquid level height H is located between its upper and lower surfaces. Therefore, the semiconductor element 55a disposed on the back side of the second substrate 52 is accommodated in a state immersed in the refrigerant liquid LQ at the lower part of the tank 10 (below the insulating oil OL), and the capacitor 55d disposed on the front side of the second substrate 52 is accommodated in a state immersed in the insulating oil OL. As a result, the cooling device 100 cools the electric circuit 50 in the following manner.

[0030] 2 is a diagram showing the state of the cooling device 100 when the electric circuit 50 is operating. When the electric circuit 50 is operating, the semiconductor element 55a and the capacitor 55d generate heat. In the cooling device 100, the electric circuit 50 is cooled by cooling with the heat of vaporization by the refrigerant liquid LQ and by heat absorption by the insulating oil OL. Because the semiconductor element 55a is immersed in the refrigerant liquid LQ, the refrigerant liquid LQ vaporizes when the semiconductor element 55a generates heat. As a result, the semiconductor element 55a, which has a relatively high heat generation density, is cooled by cooling with the heat of vaporization, and the electric circuit 50 is cooled effectively.

[0031] The capacitor 55d immersed in the insulating oil OL is cooled by dissipating heat into the insulating oil OL. This is because the capacitor 55d, which has a lower heat generation density than the semiconductor element 55a, can be sufficiently cooled by the insulating oil OL. This reduces the amount of refrigerant liquid LQ stored, and therefore the amount of expensive fluorine-based refrigerant stored. As a result, costs can be reduced compared to, for example, using only the refrigerant liquid LQ to cool the electric circuit 50. The insulating oil OL performs cooling while remaining in a liquid state without vaporizing.

[0032] The vaporized refrigerant liquid LQ moves from the lower space to the upper space within the tank 10 through the through-hole 52a. The insulating oil OL also receives heat from the vaporized refrigerant liquid LQ. As a result, part of the vaporized refrigerant liquid LQ liquefies due to heat dissipation to the insulating oil OL. The heated insulating oil OL and the vaporized refrigerant liquid LQ are cooled by the cooling liquid near the ceiling of the tank 10. As a result, the vaporized refrigerant liquid LQ also liquefies. The liquefied refrigerant liquid LQ has a higher specific gravity than the insulating oil OL. For this reason, the liquefied refrigerant liquid LQ sinks within the insulating oil OL and returns from the upper space within the tank 10 to the lower space via the through-hole 52a.

[0033] The insulating oil OL is agitated by the vaporized refrigerant liquid LQ. As a result, forced convection occurs in the insulating oil OL without the need for an additional device for forced convection, such as a pump, which increases the cooling efficiency of the heated insulating oil OL compared to natural convection. Within the tank 10, the refrigerant liquid LQ is vaporized and liquefied, causing a circulatory flow of the refrigerant liquid LQ between the lower space and the upper space. In this case, the vaporized refrigerant liquid LQ passes through some of the multiple through-holes 52a, and the liquefied refrigerant liquid LQ passes through the remaining through-holes 52a. As a result, the forced convection flows, for example, as shown by the arrows.

[0034] The air chamber AR communicates with the inside of the tank 10 via the communication path C. Therefore, the increase in internal pressure of the tank 10 due to the vaporization of the refrigerant liquid LQ is suppressed by the sub-tank 20. As a result, sealing by the sealing member 13 becomes easier. In addition, the increase in the boiling point of the refrigerant liquid LQ is suppressed, and therefore, the difficulty in cooling the heat of vaporization is suppressed. Furthermore, the air chamber AR thus provided is a separate chamber from the inside of the tank 10. Therefore, a structure that makes it difficult for the refrigerant liquid LQ to enter the air chamber AR is also obtained. The refrigerant liquid LQ is prevented from entering the sub-tank 20 in a vaporized state by the shielding plate 14, and is prevented from entering the sub-tank 20 in a liquefied state by the shielding plate 15.

[0035] The breather cap 23 maintains the inside of the tank 10 at atmospheric pressure. This suppresses fluctuations in the boiling point of the refrigerant liquid LQ, and prevents the boiling point from rising due to an increase in the internal pressure of the tank 10. This prevents a situation in which cooling by heat of vaporization is not performed until the temperature becomes higher. Furthermore, by maintaining the inside of the tank 10 at atmospheric pressure, sealing with the seal member 13 is easier than when the pressure is higher. The refrigerant liquid LQ, which is a fluorine-based refrigerant, has lower viscosity and surface tension than the insulating oil OL, and therefore easily passes through the seal member 13. Therefore, sealing with the seal member 13 is easier when the insulating oil OL is the target for leakage prevention.

[0036] Next, the main effects of this embodiment will be described.

[0037] (1) The cooling device 100 cools an electric circuit 50, which is a power semiconductor device. The cooling device 100 has a tank 10 that houses the electric circuit 50, insulating oil OL, and refrigerant liquid LQ that has a boiling point temperature lower than that of the insulating oil OL and a specific gravity higher than that of the insulating oil OL. The insulating oil OL and refrigerant liquid LQ are stored in a mixed state in the tank 10 and cool the electric circuit 50.

[0038] With this configuration, the insulating oil OL and the refrigerant liquid LQ stored in a mixed state in the tank 10 tend to exist at different positions in the vertical direction due to their different specific gravities. As a result, the refrigerant liquid LQ, which has a higher specific gravity, ends up located below the insulating oil OL. For this reason, by performing cooling with the refrigerant liquid LQ due to the heat of vaporization without adding any special device for forced convection, the insulating oil OL above can be agitated by the vaporized refrigerant liquid LQ, thereby enabling forced convection of the heated insulating oil OL. Therefore, it is possible to achieve both simplification of the device and high cooling efficiency for the heated insulating oil OL.

[0039] (2) In this embodiment, the refrigerant liquid LQ is a fluorine-based refrigerant. With this configuration, the refrigerant liquid LQ, which has a lower boiling point and a higher specific gravity than the insulating oil OL, can perform cooling by vaporization heat.

[0040] (3) The cooling device 100 further includes a sub-tank 20 having an air chamber AR, and a communication passage C that connects the air chamber AR to the inside of the tank 10. With this configuration, it is possible to suppress an increase in the internal pressure inside the tank 10 due to the evaporation of the refrigerant liquid LQ. Therefore, sealing by the sealing member 13 becomes easier. In addition, an increase in the boiling point of the refrigerant liquid LQ is suppressed, which in turn suppresses difficulty in cooling the heat of vaporization. Furthermore, because the air chamber AR is provided as a chamber separate from the inside of the tank 10, a structure can be obtained in which the refrigerant liquid LQ is less likely to enter the air chamber AR while still achieving these effects.

[0041] (4) The subtank 20 is equipped with a breather cap 23 that connects the air chamber AR to the atmosphere outside the subtank 20. With this configuration, the inside of the tank 10 is maintained at atmospheric pressure, thereby suppressing fluctuations in the boiling point of the refrigerant liquid LQ. This prevents a situation in which the boiling point increases due to an increase in the internal pressure of the tank 10, and cooling by latent heat of vaporization does not occur until the temperature reaches a higher level. Furthermore, because the inside of the tank 10 is maintained at atmospheric pressure, sealing by the sealing member 13 becomes easier.

[0042] (5) The electric circuit 50 has a semiconductor element 55a and a capacitor 55d. Of the semiconductor element 55a and the capacitor 55d, the semiconductor element 55a, which is an electronic component with a relatively high heat generation density, is accommodated in a state immersed in the refrigerant liquid LQ at the bottom of the tank 10. With this configuration, the semiconductor element 55a, which has a relatively high heat generation density, is cooled by the heat of vaporization with the refrigerant liquid LQ, thereby effectively cooling the electric circuit 50. Furthermore, since the capacitor 55d can be cooled with insulating oil OL, multiple electronic components can be appropriately cooled according to their heat generation densities, and costs can also be reduced by reducing the amount of refrigerant liquid LQ stored.

[0043] (6) The tank 10 has a first housing portion 11, a second housing portion 12, and a sealing member 13 that seals between the first housing portion 11 and the second housing portion 12 that are joined together. The sealing member 13 is provided in a range in the height direction where the insulating oil OL is stored according to its specific gravity. With this configuration, the insulating oil OL is the target for preventing leakage, making it easy to seal with the sealing member 13.

[0044] The electrical circuitry 50 may be housed in a cooling device 100 as follows.

[0045] 3 and 4 are diagrams illustrating modified examples of the electric circuit 50 and the cooling device 100. In the example shown in FIG. 3, the first substrate 51 is provided on the bottom surface of the tank 10 and is electrically connected to the second substrate 52 via connectors and wiring. The multiple through holes 52a may be provided in a position that overlaps the first substrate 51 in the vertical direction. The second substrate 52, together with the boss 10a, is provided higher than in the present embodiment shown in FIGS. 1 and 2, while the liquid level H of the refrigerant liquid LQ is the same as in the present embodiment. As a result, in this example, the semiconductor element 55a is located below the liquid level H, and the capacitor 55d is located above the liquid level H. Therefore, the semiconductor element 55a is accommodated in the lower part of the tank 10 while immersed in the refrigerant liquid LQ, and the capacitor 55d is accommodated in the insulating oil OL while immersed in the insulating oil OL. Even in this configuration, the vaporized refrigerant liquid LQ can agitate the insulating oil OL above, thereby forcing the heated insulating oil OL to circulate. This allows for both a simplified device and high cooling efficiency for the heated insulating oil OL.

[0046] In the example shown in FIG. 4, compared to the example shown in FIG. 3, the electric circuit 50 further includes a third board 53, and the tank 10 further includes a boss 10d. The boss 10d is provided on the first housing 11, and the third board 53 is fixed to the boss 10d from the opening side of the first housing 11. Therefore, the third board 53 is provided above the second board 52. The third board 53 is provided below the through-hole 10c. A diode 55e is mounted on the third board 53. A plurality of diodes 55e are provided and are components of the circuit unit 55. Therefore, in this example, the circuit unit 55 is mounted on the first board 51, the second board 52, and the third board 53, and the third board 53 is electrically connected to the first board 51 and the second board 52 via connectors and wiring. The diode 55e, like the capacitor 55d, has a lower heat generation density than the semiconductor element 55a and is housed immersed in insulating oil OL. That is, in this example, the diode 55e, together with the capacitor 55d, is one example of a plurality of electronic components included in the electric circuit 50, other than the semiconductor element 55a. Even in this configuration, the insulating oil OL above can be agitated by the vaporized refrigerant liquid LQ, thereby allowing the heated insulating oil OL to be forced to circulate, so that it is possible to achieve both simplification of the device and high cooling efficiency for the heated insulating oil OL.

[0047] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0048] For example, the sub-tank 20 may have an air breather mechanism formed integrally with the tank portion 21 instead of the breather cap 23 . [Explanation of symbols]

[0049] 10 Tank 10c through hole 11 First housing section 12 Second housing section 13 Sealing material 20 Subtank 21 Tank section 22 Connection 23 Breather cap (air breather mechanism) 11 cases 12 Electrical Circuits 50 Electrical Circuits 50 55 Circuit section 55a Semiconductor elements 55d capacitor 100 Cooling device AR Air Chamber C communication path LQ refrigerant liquid (fluorine-based refrigerant) OL insulating oil

Claims

1. A cooling device for cooling power semiconductor equipment, a tank that accommodates the power semiconductor device; Insulating oil and a refrigerant liquid having a boiling point lower than that of the insulating oil and a specific gravity higher than that of the insulating oil; and the insulating oil and the refrigerant liquid are stored in a mixed state in the tank to cool the power semiconductor device; In cooling the power semiconductor device, the refrigerant liquid cools the heat of vaporization, the refrigerant liquid is a fluorine-based refrigerant, the tank has a first housing portion and a second housing portion, and a seal member that seals between the first housing portion and the second housing portion that are joined to each other, The sealing member is provided within a range in the height direction in which the insulating oil is stored according to its specific gravity. Cooling device.

2. A cooling device for cooling power semiconductor equipment, comprising: a tank that accommodates the power semiconductor device; Insulating oil and a refrigerant liquid having a boiling point lower than that of the insulating oil and a specific gravity higher than that of the insulating oil; and the insulating oil and the refrigerant liquid are stored in a mixed state in the tank to cool the power semiconductor device; In cooling the power semiconductor device, the refrigerant liquid cools the heat of vaporization, a sub-tank having an air chamber; a communication passage that communicates the air chamber with the inside of the tank; a shielding plate or pipe member provided on the inner surface of the side wall of the tank around an opening of a through hole of the communication passage penetrating the side wall, the shielding plate or pipe member preventing the refrigerant liquid from entering the sub-tank from the tank; further comprising Cooling device.

3. A cooling device according to claim 2, The sub-tank is provided with an air breather mechanism that connects the air chamber with the atmosphere outside the sub-tank. Cooling device.

4. A cooling device according to any one of claims 1 to 3, the power semiconductor device has a plurality of electronic components with different heat generation densities, Among the plurality of electronic components, electronic components with a relatively high heat generation density are accommodated in a state where they are immersed in the refrigerant liquid at a lower portion within the tank. Cooling device.

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