JPH05172610A - Oil level detection device within closed container according to ultrasonic wave - Google Patents

Abstract

PURPOSE:To enable an oil level position within a tank to be detected accurately by fixing a parallel ultrasonic reflection plate for a side wall within a sealed type metal tank and then providing an ultrasonic probe which can move up and down on an outer-wall surface of the tank so that the probe opposes the wall. CONSTITUTION:A reflection wave is scanned by moving an ultrasonic probe 11 in upper and lower directions. An ultrasonic flaw-detection machine 12 detects arrival time and strength of the reflection wave according to the reflection wave. A high detection sensitivity can be obtained since the probe 11 detects a reflection wave with a large strength from an ultrasonic reflection plate 21. Also, arrival time and strength of the reflection wave change in steps corresponding to a difference in propagation characteristics of ultrasonic wave at liquid-phase and gaseous phase parts of fluorocarbon with a liquid face 7 as a boundary in scanning process. By detecting this step-shaped change point, a position of the liquid face 7 can be known. By marking a detection liquid-face position on an outer-wall surface of the tank at the time of initial measurement, presence or absence of failure of closing performance can be judged easily according to deviation of the liquid-face position which is detected at the time of periodical inspection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes the difference in the ultrasonic wave propagation characteristics between the liquid phase and the vapor phase of the liquid surface in a sealed metal tank containing a fluorocarbon liquid as a boiling cooling medium liquid. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detecting device for detecting, and particularly to a liquid level detecting device for boiling cooling type electric equipment.

[0002]

2. Description of the Related Art In the boiling cooling method, a heating element can be efficiently and directly cooled by utilizing the large latent heat of vaporization of a boiling cooling medium liquid, so that a power semiconductor element having a heating portion with a locally high heat flow density is used. It is widely used as a cooling method for power converters. FIG. 2 is a side sectional view schematically showing a boiling cooling type rectifying device using a fluorocarbon liquid as a boiling cooling medium liquid, and a sealed metal tank 2 accommodating a heat generating part 1 of the rectifying device is provided on the upper part thereof. The sealed metal tank 2 is provided with a radiator 3 in communication therewith, and in the sealed metal tank 2, a fluorocarbon liquid 9L as a boiling cooling medium liquid is positioned at a liquid level 7 so that the heat generating portion 1 of the rectifier is immersed to a predetermined depth. Is held and enclosed, and the sealed space above the liquid surface is evacuated in advance to form a gas phase portion filled with 9V of fluorocarbon vapor.

In the boiling cooling type rectifier constructed as described above, the heat generated by the electrical loss of the heat generating portion 1 of the rectifier is a fluorocarbon liquid 9L in contact with the high temperature portion.
Is cooled by boiling, and the vaporized fluorocarbon vapor 9V releases its latent heat and sensible heat into the atmosphere by the radiator 3 to be condensed and condensed, and the fluorocarbon liquid whose temperature has decreased is a sealed metal. By returning to the tank 2, the liquid level 7 and the heat generating portion of the rectifying device are maintained at a predetermined position and temperature, respectively, to operate.

Further, a fluorocarbon as a boiling cooling medium liquid.
The boiling point of Bonn liquid 9L is higher than that of fluorocarbon refrigerants,
It is common that the fluorocarbon liquid in contact with the locally high temperature part of the rectifier reaches the boiling point and is in a boiling state, and the vapor pressure of the fluorocarbon in the sealed metal tank 2 and the radiator 3 is equal to that of the rectifier. Even during operation, the negative pressure state is maintained with respect to atmospheric pressure. Therefore, it is important to keep the sealed metal tank 2 in a completely sealed state, and a liquid level detection device or a liquid level display device having a portion penetrating the tank wall may impair the sealing performance of the sealed metal tank. Therefore, the liquid level 7 of the fluorocarbon solution 9L in the sealed metal tank 2 is managed by setting the amount of the fluorocarbon solution 9L enclosed in the sealed metal tank 2 to a designated amount calculated in advance. The actual situation is that it is indirectly managed by weighing and enclosing it.

[0005]

However, since the internal pressure changes each time the boiling cooling type rectifying device is repeatedly operated and stopped, there is no possibility that the sealing performance of the sealed metal tank or the radiator will deteriorate during long-term operation. However, it is not possible to say that the liquid level must be regularly inspected. Therefore, it is required to establish a measurement technique that can detect the liquid level position of the fluorocarbon liquid from the outside of the sealed container. Therefore, the application of the ultrasonic liquid level detection device is conceived, and as shown in FIG. 2, the ultrasonic probe 11 is placed on the lower surface and the upper surface of the sealed metal tank 2 at a position where the heat generating portion 1 of the rectifier does not intervene. The ultrasonic wave emitted toward the liquid surface 7 is reflected by the liquid surface, the detection delay time of the reflected wave and the intensity of the reflected wave are detected by the ultrasonic flaw detector 12, and the fluorocarbon liquid 9L is attached. Also, an attempt was made to find the position of the liquid surface 7 from the propagation velocity of ultrasonic waves in the fluorocarbon vapor 9V.

This method is generally used for detecting the liquid surface position in a closed tank, but unexpectedly, the ultrasonic probe on the liquid phase side as well as the ultrasonic probe on the liquid phase side is unexpectedly expected. It was found that the reflected sound could not be detected even from the tentacles. The cause is that the propagation velocity of the ultrasonic wave in the fluorocarbon liquid phase is as slow as 1/10 or less of that of the iron tank wall, and the difference from the propagation velocity in the fluorocarbon vapor phase is small, so that The reflected wave is weak, and the reflectance of the reflected wave on the inner wall of the tank is high,
It is considered that the force of the reflected wave that passes through the tank wall and reaches the ultrasonic probe is extremely reduced. From this result, it was revealed that the position of the liquid surface of the fluorocarbon liquid cannot be detected by the known detection method for detecting the reflected wave from the liquid surface.

An object of the present invention is to obtain an ultrasonic liquid level detecting device in a sealed container capable of detecting the liquid level position by a simple operation of applying an ultrasonic probe to the outer wall surface of a sealed metal tank. It is in.

[0008]

In order to solve the above-mentioned problems, according to the present invention, the liquid level of the boiling cooling medium liquid in a hermetically sealed metal tank containing a heat generating part of an electric appliance and a boiling cooling medium liquid. Is detected by an ultrasonic probe closely attached to the outer wall surface of the sealed metal tank, and is parallel to the side wall of the sealed metal tank at a predetermined distance. An ultrasonic reflector fixed to
An ultrasonic probe is provided in close contact with the outer wall surface of the sealed metal tank so as to be vertically movable so as to face the ultrasonic reflection plate.

The boiling cooling medium liquid is a fluorocarbon liquid.

Further, it is assumed that the electric device is a boiling cooling type electric device.

[0011]

In the structure of the present invention, the ultrasonic wave reflecting plate is fixed in parallel to the side wall of the hermetically sealed metal tank, and the hermetically sealed metal tank is opposed to the ultrasonic wave reflecting plate. By arranging the ultrasonic probe in close contact with the outer wall surface of the ultrasonic probe so that it can move up and down, the ultrasonic wave emitted from the ultrasonic probe in parallel with the liquid surface has a high reflection efficiency. The ultrasonic probe can receive high-intensity reflected waves that are reflected by the acoustic wave reflector, and by moving the ultrasonic probe up and down, the ultrasonic wave is reflected at the liquid phase side and the gas phase side with the liquid level as the boundary. Since there is a difference in the arrival time of the wave and the intensity of the reflected wave, the function of easily identifying the liquid surface position can be obtained. Therefore, it becomes possible to detect the liquid level which was difficult by the conventional method when the fluorocarbon liquid is used as the boiling cooling medium liquid, and the liquid surface position of the boiling cooling type electric device using the fluorocarbon liquid is regularly inspected. This can be easily performed using a commercially available ultrasonic flaw detector.

[0012]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a sectional view showing an example of a boiling-cooling type rectifier of a liquid level detecting device in an airtight container by ultrasonic waves according to an embodiment of the present invention. The same components as those of the prior art are designated by the same reference numerals. Therefore, duplicate description will be omitted. In the figure, an ultrasonic reflection plate 21 made of a metal plate or an insulating plate is mounted in parallel in the sealed metal tank 2 with a predetermined distance between it and the side plates of the tank. The fluorocarbon liquid 9L and the fluorocarbon vapor 9V freely flow through the gap between the ultrasonic reflection plate and the inner wall of the tank via the flow section 22, and the position of the liquid surface 7 is maintained. Also,
The ultrasonic probe 11 is closely attached to the outer wall surface of the side plate of the hermetically sealed metal tank 2 so as to be movable above and below with the liquid level 7 interposed therebetween. It is configured to receive the reflected wave from the sound wave reflection plate, convert it into an electric signal, and transmit it to the ultrasonic flaw detector 12.

In the liquid level detecting device in the hermetically sealed container by the ultrasonic wave constructed as described above, the ultrasonic probe 11 is moved in the vertical direction to scan the reflected wave, and the reflected wave detected by the ultrasonic probe is detected. Since the ultrasonic flaw detector 12 detects the arrival time and the intensity of the reflected wave from the wave, the ultrasonic probe detects the high-intensity reflected wave from the ultrasonic reflection plate 21 having high reflection efficiency. In addition to high sensitivity, the arrival time and intensity of the reflected wave at the liquid level 7 as a boundary in the scanning process are stepwise corresponding to the difference in the ultrasonic wave propagation characteristics between the liquid phase portion and the vapor phase portion of the fluorocarbon. Since it changes, the position of the liquid surface 7 can be easily known by detecting this stepwise change point. If the liquid level position detected during the initial measurement is stamped on the outer wall surface of the sealed metal tank, it is possible to easily determine whether there is an abnormality in the tank sealing performance from the deviation of the liquid level position detected during the periodic inspection. You can

Fluorocarbon liquid and fluorocarbon
Since the propagation speed of ultrasonic waves in Bonn vapor is low, the arrival time of reflected waves can be accurately detected even if the distance between the ultrasonic reflector and the tank wall is set to about several cm. It is possible to prevent the sealed metal tank from increasing in size due to the provision of the above, and to prevent the bubbles of fluorocarbon vapor from penetrating into the gap and hindering the normal propagation of ultrasonic waves by the ultrasonic reflector serving as a partition. Therefore, even when the rectifying device is in operation, the liquid level position can be detected by eliminating the influence of bubbles generated in the fluorocarbon liquid by boiling cooling.

The liquid level detecting device in an airtight container using ultrasonic waves according to the present invention is not limited to boiling cooling type electric equipment, and is widely used for detecting the liquid level of a sealed metal tank using a fluorocarbon liquid as a cooling medium. Can be used.

[0016]

As described above, according to the present invention, the ultrasonic reflecting plate is fixed in parallel to the side wall of the sealed metal tank at a predetermined distance, and the ultrasonic reflecting plate is opposed to the ultrasonic reflecting plate. The ultrasonic probe was arranged in close contact with the outer wall surface of the sealed metal tank so as to be vertically movable. As a result, the ultrasonic probe can obtain high detection sensitivity because it detects the reflected wave from the ultrasonic reflection plate with high reflection efficiency, and the ultrasonic probe is moved up and down on the tank wall to reflect. By performing wave scanning, the arrival time and intensity of the reflected wave change stepwise with the liquid surface as the boundary, so the liquid surface position can be easily detected, so the reflected wave from the liquid surface can be detected. Detecting the liquid surface position of the fluorocarbon solution that could not be detected by the conventional technology
It is possible to economically advantageously provide a liquid level detection device in a closed container using ultrasonic waves, which can be performed with high sensitivity and accuracy by simply changing the structure by adding an ultrasonic wave reflection plate.

Further, since the liquid level of the fluorocarbon solution in the sealed metal tank can be easily detected by a simple operation of bringing the ultrasonic probe into contact with the outside of the tank, the fluorocarbon solution is cooled by boiling. Periodic inspection of the liquid level position of the boiling cooling type electric device as a medium is facilitated, and if the initial value of the liquid level position is measured when the fluorocarbon liquid is filled, the liquid level will be changed during the periodic inspection of the boiling cooling type electric device. By confirming that there is no change in the surface position, it is possible to monitor the abnormality of the sealed state of the boiling cooling type electric equipment, so it is possible to prevent the thermal breakdown accident of the power semiconductor element due to the decrease of the liquid level. Is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a boiling cooling type rectifier of a liquid level detection device in an airtight container using ultrasonic waves according to an embodiment of the present invention.

FIG. 2 is a side sectional view schematically showing a boiling cooling type rectifying device using a fluorocarbon liquid as a boiling cooling medium liquid.

[Explanation of symbols]

 1 Heat generating part of rectifier 2 Sealed metal tank 3 Radiator 7 Liquid level 9L Fluorocarbon liquid (liquid phase) 9V Fluorocarbon vapor (gas phase) 10S Ultrasonic wave 11 Ultrasonic probe 12 Ultrasonic flaw detector 21 Ultrasonic wave reflector 22 Distribution section

Claims (3)

[Claims] 1. A superconducting device in which a liquid level of the boiling cooling medium liquid in a sealed metal tank containing a heat generating part of an electric appliance and a boiling cooling medium liquid is closely attached to an outer wall surface of the sealed metal tank. An ultrasonic wave reflector, which is detected by an acoustic wave probe, is fixed in parallel to the side wall of the sealed metal tank at a predetermined distance, and faces the ultrasonic wave reflector plate. And an ultrasonic probe disposed in close contact with the outer wall surface of the sealed metal tank so as to be vertically movable. 2. The liquid level detecting device in an airtight container using ultrasonic waves according to claim 1, wherein the boiling cooling medium liquid is a fluorocarbon liquid. 3. The liquid level detection device in an airtight container according to claim 1, wherein the electric equipment is a boiling cooling type rectifying device.