JP2005340570A - Ebullient cooling device for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure an ebullient cooling function for a semiconductor device arrayed on the lower surface of a bottom wall by suppressing the biasing flow of a refrigerant sealed in a tank even in a state that the posture of a cooling unit is slanted, in the object of ebullient cooling device applied for a power converter mounted to a rolling stock. <P>SOLUTION: An ebullient cooling unit 2 is constituted of a flat tank 5 for sealing a liquid phase refrigerant 4 and condensing units 6 arranged continuously on the upper side of the tank. The ebullient cooling device is provided with power semiconductor devices 1 arrayed in parallel on the lower surface of the bottom wall of the tank, and mounted so as to transfer heat to discharge the generating heat of the semiconductor device to the outside of a system utilizing the phase change (evaporation-condensation cycle) of the refrigerant. In such an ebullient cooling device, eaves-like blocks 7 for covering the upper part of the level of the refrigerant in a region excluding a central region in the tank are provided in the tank as a liquid level control member for suppressing the biasing flow of the refrigerant liquid by the slanting of the posture of the device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a boiling cooling device for a semiconductor device applied to a power conversion device mounted on a railway vehicle.

  As is well known, a converter / inverter type power converter using a power semiconductor device as a main circuit element is adopted as a main circuit system for driving and controlling a main motor in recent railway vehicles. Moreover, what employ | adopted the boiling cooling system for cooling of the power semiconductor device with which this power converter device was equipped is conventionally known (for example, refer patent document 1, 2).

  Next, FIG. 2 shows a conventional configuration of a boiling cooling device applied to the power conversion device. In FIG. 2, 1 is a converter of a power conversion device, a diode as a main circuit element constituting an inverter unit, a power semiconductor device such as IGBT, 2 is a boiling type cooling unit, and 3 is a wind tunnel through which cooling air is passed. . Here, the boiling type cooling unit 2 is a tank 5 that is a flat pressure vessel in which a refrigerant (liquid phase refrigerant) 4 such as alternative chlorofluorocarbon is decompressed and enclosed, and an air-cooled condensation on the upper surface side of the tank 5. A plurality of power semiconductor devices 1 constituting a bridge circuit of a power converter are juxtaposed on the lower surface of the bottom wall of the tank 5 and mounted in a heat transfer manner. Is arranged in the ventilation path in the wind tunnel 3. The power converter is entirely covered with an outer box, and is mounted and mounted under the floor of a railway vehicle.

The principle of the boiling cooling device is well known, and heat generated by energization of the power semiconductor device 1 is transferred to the tank 5 to boil the refrigerant 4 enclosed in the tank. At this time, the refrigerant absorbs latent heat of vaporization. To do. Further, the refrigerant vapor diffuses into the space above the refrigerant liquid level and moves from the tank 5 to the condensing unit 6 where the pressure is low. Here, the cooling air that flows through the wind tunnel 3 (air outside air is taken in by the blower blower) The latent heat of vaporization is dissipated out of the system and condensed by heat exchange with the air sent to the cylinder 3, and then the liquefied refrigerant flows down to the tank 5 and recirculates again. By repeating this evaporation-condensation phase change cycle, the generated heat of the power semiconductor device 1 is efficiently transported and dissipated into the cooling air outside the system.
Japanese Patent Laid-Open No. 11-3971 JP 2003-219507 A

  By the way, the above-described conventional boiling cooling device mounted on a railway vehicle as a means for cooling the semiconductor device of the power converter has the following problems.

  That is, when the vehicle body tilts due to vehicle acceleration, deceleration, roll, and track gradient, the cooling unit 2 also tilts from the horizontal posture as shown in FIG. As a result, the state of the liquid level H changes. In this case, as shown in the figure, when the cooling unit is tilted in the direction of the arrow (downward to the left), the refrigerant 4 flows in the tank and shifts to the left side, and the surface area of the right end side bottom wall opposite to this is exposed. In this surface area, the boiling heat transfer of the refrigerant 4 does not act on the surface area because it is in a “liquid withering” state that is not immersed in the refrigerant liquid 4. In such a state, among the power semiconductor devices 1 distributed and arranged on the bottom surface of the tank 5, the cooling action on the semiconductor devices arranged in the rightmost column becomes only the heat conduction with the tank 5 and is extremely reduced. As a result, there is a possibility that the temperature of the semiconductor device 1 rises above the allowable temperature and is thermally destroyed.

  Conventionally, with respect to such a problem, the height of the tank 5 is increased, and the amount of the refrigerant 4 enclosed therein is increased so that the liquid level height H in the tank is sufficiently high. However, even if the vehicle body is tilted while the vehicle is running, the tank 5 of the cooling unit 2 is dealt with by preventing the above-mentioned “liquid draining” phenomenon from occurring. In addition to the increase in the size of the cooling device, the amount of the enclosed refrigerant was increased, causing problems such as an increase in material cost and an increase in weight.

  The present invention has been made in view of the above points, and by installing a simple functional component inside the tank of the boiling cooling unit, when the cooling unit is tilted, the refrigerant flows in an offset direction in the tank. An object of the present invention is to provide a boiling cooling device for a semiconductor device which is improved so that the boiling cooling function of a semiconductor device mounted on the lower surface of a bottom wall of a tank can be maintained.

In order to achieve the above object, according to the present invention, a flat tank filled with a liquid-phase refrigerant and a condensing part connected to the upper side of the tank are provided. In the boil cooling device in which the devices are arranged side by side and mounted in a heat transfer manner, and the generated heat of the semiconductor device is released out of the system using the phase change of the refrigerant,
A liquid level control member is provided in the tank to prevent the refrigerant liquid from drifting in the tank due to the inclination of the posture of the apparatus (Claim 1). Specifically, the liquid level control member is The configuration is as described below.
(1) The liquid level control member is constituted by a bowl-shaped block that covers the upper surface of the refrigerant in the region excluding the central portion in the tank.
(2) In the preceding paragraph (1), the block has a taper on the upper and lower surfaces so that the cross-sectional shape tapers from the outer periphery toward the central opening, and the tank and the condensing part are associated with the refrigerant evaporation-condensation cycle. The refrigerant vapor and the refrigerant liquid moving between the two are guided along the tapered surface.

According to the above configuration, even when the posture of the cooling unit is tilted, the refrigerant liquid sealed in the tank is not restrained by the block and flows extremely sideways, and the entire bottom wall of the tank is immersed in the refrigerant liquid. Maintain the state. This prevents the “bottom of liquid” phenomenon on the tank bottom wall that accompanies the tilt of the cooling unit, which has been a problem with conventional equipment, and ensures a stable boiling cooling function for semiconductor devices arranged side by side on the bottom side of the tank. Reliability can be improved.
In addition, since the above-mentioned “liquid withering” can be effectively suppressed, the tank volume can be reduced and the amount of refrigerant filled can be reduced, thereby contributing to the reduction in size and weight of the cooling device.

  Embodiments of the present invention will be described below based on the examples shown in FIGS. 1 (a) and 1 (b). (A) shows a steady state in which the posture of the cooling unit 2 is horizontal, and (b) shows a state in which the cooling unit is tilted. In the drawings of the embodiment, members corresponding to FIGS. Are denoted by the same reference numerals and their description is omitted.

  That is, in the boiling cooling unit 2 of the illustrated embodiment, a block 7 is additionally provided as a liquid level control member inside the tank 5 in which the refrigerant 4 is enclosed. The block 7 is a bowl-shaped plate that protrudes from the peripheral wall of the tank 5 toward the center and covers the upper surface of the liquid level H of the refrigerant 4. The space communicates up and down. In addition, the upper and lower surfaces are tapered so that the cross-sectional shape of the block 7 tapers from the outer periphery toward the central opening 7a, and between the tank 5 and the condensing unit 6 in accordance with the refrigerant evaporation-condensation cycle. In this way, the refrigerant moving up and down is guided without stagnation along the tapered surface.

  In the above-described configuration, in the steady state of FIG. 1A, similarly to the case described with reference to FIG. 2, the refrigerant 4 that has received heat generated from the power semiconductor device 1 and enclosed in the tank repeats the evaporation-condensation cycle to cool the semiconductor device. To do. The refrigerant vapor boiled and vaporized in the tank 5 and the refrigerant liquid condensed and liquefied in the condensing unit 6 are guided along the taper surface of the block 7 and move up and down through the central opening 7a, and this evaporation-condensation cycle. The heat generated by the semiconductor device 1 is released to the outside of the system through the condenser 6 by heat transport by repeating the above.

  On the other hand, when the cooling unit 2 is inclined as shown in FIG. 1B due to the inclination of the railway vehicle on which the cooling device is mounted, it is enclosed in the tank 5 corresponding to the inclination direction of the attitude. As described in FIG. 3, the refrigerant liquid tends to flow toward the lower side of the tank. However, in the illustrated embodiment, the offset flow of the refrigerant 4 is suppressed by the block 7 provided in the tank, and the liquid level is reduced. H is maintained in the illustrated state. Therefore, as described in FIG. 3, the tank bottom wall is not exposed above the liquid level H of the refrigerant 4 in the right end side region of the tank 5, so that a so-called “liquid drainage” state does not occur. Regardless of whether the posture is inclined or not, it is possible to secure a boiling cooling function for all the power semiconductor devices 1 arranged in parallel on the lower surface of the tank 5.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the structure of a boiling cooling device by an Example of this invention, and an effect | action, (a), (b) is the figure showing the state of the steady attitude | position of a cooling unit, and the inclination attitude | position, respectively. A diagram showing the state of the cooling unit in a steady posture in the configuration diagram of the conventional boiling cooling device The figure showing the state in which the attitude | position of the cooling unit inclined in the structure of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power semiconductor device 2 Boiling cooling unit 4 Refrigerant 5 Tank 6 Condensing part 7 Block (liquid level control member)
7a Center opening

Claims (3)

It consists of a flat tank filled with a liquid-phase refrigerant and a condensing part connected to the upper side of the tank. Power semiconductor devices are arranged side by side on the bottom wall of the tank, and are installed in a heat transfer manner. In the boiling cooling apparatus in which the heat generated by the device is released from the system using the phase change of the refrigerant,
A boiling cooling device for a semiconductor device, characterized in that a liquid level control member is provided in the tank to prevent the refrigerant liquid from drifting in the tank due to the inclination of the posture of the device. 2. The boiling cooling apparatus according to claim 1, wherein the liquid level control member is a bowl-shaped block that covers the upper surface of the refrigerant in a region excluding the central portion in the tank. Cooling system. 3. The boiling cooling device for a semiconductor device according to claim 2, wherein the block has a tapered upper and lower surface so that a cross-sectional shape thereof is tapered from the outer periphery toward the central opening. .

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