JPS61170633A - Pressure control device for cavitation tank - Google Patents

Abstract

PURPOSE:To control the pressure inside a tank to the set value and to make the prescribed pressure range controllable continuously by using the atmosphere for adjusting the pressure rise in pressure reduction control system and by performing the control of the flow of this atmosphere by pressurizing adjusting valve. CONSTITUTION:At the operation time of a pressure reduction control system auxiliary pressure reduction adjusting valve 61B, the switching valve 72 for pressurizing are fully closed and an inlet valve 74 is fully opened. And when the pressure set value corresponding to the necessary pressure inside the tank is set to a programmable adjusting meter, the adjusting meter 100 performs PID operation of the difference between the pressure set value P0 and the pressure detected value P1 which is from a pressure gage 42, controls the opening of the pressure reduction adjusting valve 61A in case of the positive and controls the opening of the pressurizing adjusting valve 71A in case of the negative. The tank pressure is dropped by exhausting from the pressure adjusting tank 33 by the opening control of the valve 61A, the tank pressure is raised by feeding the air to the pressure adjusting tank 33 by the opening control of the valve 71A and the pressure inside the tank is adjusted by pressure rise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure control device for a gear cavitation water tank, and in particular to a pressure control device for a cavitation water tank, which allows independent operation and continuous operation by automatic switching of a depressurization control system and a pressurization control system. It relates to a pressure control device.

[Conventional technology]

The cavitation tank is used, for example, to simulate the state of yapitation inside the sea urchin fish ship Gubera and measure the thrust and torque of Fa Bella, or to observe the state of cavitation occurrence. This is a test tank.

FIG. 3 shows an example of a conventional vertical cavitation water tank 21, in which a circulation flow path 22 has a lower horizontal flow path 23 and a vertical flow that communicates with both ends of the lower horizontal flow path 23 and projects upward. channel 25.26 and these vertical flow channels 25.26
The upper horizontal flow passages 28 are connected to the upper ends of the upper horizontal flow passages 28, respectively.

A bonder 31 driven by a motor 29 is installed in the lower horizontal flow path 23, and the tank 31 allows the circulation flow path 2
It is designed to circulate the water inside 2.

The cavitation water tank 21 is equipped with a pressure adjustment tank 33 having a water surface at a height H (usually 1 m) from the center of the measurement section 32, and the pressure of the pressure adjustment tank is controlled by a pressure control mechanism described below. The pressure inside the tank is adjusted. The pressure inside this tank can be adjusted normally within the range of 0°1 to 2.0 bar (absolute pressure), so that cavitation can be generated under arbitrary conditions.

Conventionally, pressure control in a cavitation water tank has been performed using two independent systems: a pressure reduction control system that sets the pressure adjustment tank 33 below atmospheric pressure, and a pressurization control system that sets it above atmospheric pressure, as shown in Figure 3. It is. That is, the pressure reduction control system includes a vacuum pump 34, a vacuum tank 35, and a pressure reduction adjustment valve 36.
, an intake valve 37, and a pressure reduction regulator 38, and the pressure reduction regulator calculates the difference between the pressure detection value by the pressure reduction pressure gauge 40 installed in the measurement section of the cavitation water tank and the pressure reduction setting value from P. Then, an opening command signal for the pressure reduction regulating valve 36 and an opening/closing command signal for the intake valve 37 are output. Then, the pressure in the cavitation water tank is determined by the pressure reduction controller 3.
This is done by operating both valves based on a command signal from 8 and controlling the tank pressure by exhausting the pressure regulating tank 33 or supplying atmospheric air to the tank. On the other hand, the pressurization control system is the compressor 50. The air tank 51 is connected to a pressurization adjustment valve 52, an exhaust valve 53, and a pressurization controller 54, and the pressurization controller is connected to the middle cavitation water tank O.
The difference between the pressure detected by the pressurization pressure gauge 41 installed in the measurement unit and the pressurization set value is calculated from P, and the pressure adjustment valve 52
An opening command signal for the exhaust valve 53 and an opening/closing command signal for the exhaust valve 53 are output. The pressure in the cavitation water tank is determined by operating both valves based on the command signal output from the pressurizing cylinder needle 54 to supply air to the pressure X* tank 33 or release it from the tank to the atmosphere. This is done by controlling the pressure.

[Problem that the invention seeks to solve]

However, with conventional pressure control devices, it is necessary to select a different g meter depending on whether the desired pressure in the tank is higher or lower than atmospheric pressure, so it is difficult to continuously variable pressure control across both am meters. Because it was necessary to manually switch from the depressurization control system to the pressurization control system, automatic setting operation was not possible. Further, since the distance between the pressure detection position of the measuring section and the water surface of the pressure adjustment tank, that is, the head difference E, is 1 m, the pressure at the pressure detection position is 1.1 bar under standard atmospheric pressure. Therefore, in order to control the pressure inside the tank to the above pressure, it is necessary to control the pressure N adjustment to atmospheric pressure, and in the end, the intake valve \37 of the pressure reduction control system or the exhaust valve 53 of the pressure control system is opened. As a result, the pressure inside the tank depended on fluctuations in atmospheric pressure, making it necessary to conduct unstable experiments.

An object of the present invention is to provide a pressure control device for a cavitation water tank that can control the pressure inside the tank to a set value and continuously control a predetermined pressure range. The pressure control device for a cavitation water tank of the invention connects a pressure adjustment port to a circulation flow path, provides a pressure adjustment mechanism in the pressure adjustment tank, and adjusts the pressure adjustment mechanism based on the pressure at a measurement section of the circulation flow path. In the pressure control device for a cavitation water tank, the pressure control device operates to control the pressure in the pressure adjustment tank to adjust the pressure inside the tank. The pressure sources are connected to each other, a pressurization on-off valve is interposed between the pressurization adjustment means and the pressurization source, and an intake valve is provided in a pipe line between the pressurization adjustment means and the pressurization on-off valve. and a pressure regulating mechanism that is connected to an intake pipe open to the atmosphere and equipped with a regulator that controls each of the regulating means and each valve based on the detected pressure of the measuring section, and the regulator is connected to a pressure regulating mechanism that is connected to an intake pipe that is open to the atmosphere. A pressure reduction control system that reduces the pressure in the tank by operating the pressure reduction adjustment means and increases the pressure by introducing atmospheric air by operating the pressure adjustment means to adjust the pressure in the tank; Independent operation by one of the control systems of the pressurization control system, which increases the pressure by supplying compressed air from the pressurization source by operation, and reduces the pressure by operating the pressure reduction adjustment means to adjust the pressure in the tank, and both controls. The system is configured to enable automatic switching operation in which the pressure inside the tank is continuously and variably controlled by combining systems.

[For production]

According to the above configuration, in the pressure reduction control system, a pressure lower than the internal pressure of the pressure regulating tank at standard atmospheric pressure is set as the upper limit setting pressure, and the tank internal pressure below the upper limit setting pressure is adjusted.

In this operation, the intake valve is opened, the opening of the pressure reducing adjustment valve is controlled based on the detection signal of the pressure inside the tank, air is exhausted from the pressure adjustment tank, the tank pressure is lowered, and the inside of the tank is adjusted to the set pressure. do.

At this time, if the pressure inside the tank fluctuates and becomes lower than the set pressure, the opening degree of the pressurization adjustment valve is controlled and atmospheric air is supplied to the pressure shrine tank via the pressurization on-off valve. Increase the pressure and adjust to the set value. On the other hand, in the operation of the pressurization control system,
The intake valve is fully closed and the pressurization on-off valve is fully opened, and the opening degrees of the pressure reduction adjustment valve and pressure adjustment valve are controlled based on the detection signal of the tank pressure, and the lower limit is slightly lower than the upper limit set pressure of the pressure reduction control system. The pressure inside the tank is controlled within a pressure range from the set pressure to the upper limit set pressure, which includes the pressure inside the tank at standard atmospheric pressure in the pressure adjustment tank. In other words, in a pressurization control system, when the pressure inside the tank changes to be lower than the set value, the pressure adjustment valve is operated and air is supplied to the pressure adjustment tank to increase the tank pressure. When the tank pressure changes to higher than the set value, the pressure reducing valve is operated and the pressure adjustment tank is evacuated to lower the tank pressure, reducing the tank pressure. Automatically adjust to the set value.

In addition, in automatic switching operation between the depressurization control system and the pressurization control system, when the pressure setting value is continuously changed from the lower limit pressure of the depressurization control system to the upper limit pressure of the pressurization control system, the controller changes. Continuously calculates the difference between the pressure set value and the detected pressure value using P, selects an optimal control system from the detected pressure value, and includes a pressure adjusting means belonging to the control system selected based on the calculation result; A control signal is output to the six valves to continuously change the pressure in the pressure adjustment tank, thereby continuously variable controlling the pressure inside the tank.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. The basic structure of the cavitation water tank is the same as the conventional one shown in FIG. 3, so structural parts having the same functions are given the same reference numerals and their explanations will be omitted.

The pressure adjustment tank 33 includes a vacuum tank 35 for exhausting air.
and an air tank 51 for supplying compressed air. A pipe line 60 connecting the pressure adjustment tank 33 and the vacuum tank 35 is provided with a pressure reduction adjustment means 61 in which a pressure reduction adjustment valve 61A and an auxiliary pressure reduction adjustment valve 61B are arranged in parallel. air tank 5
1 is interposed with a pressure regulating valve 71 as a pressure regulating means 71 on the pressure regulating tank side and a pressurizing on/off valve 72 on the air tank side, An intake pipe 73 for introducing atmospheric air is connected to a pipe line 70A between the pressurization adjustment valve 71A and the pressurization on-off valve 72. Note that the auxiliary pressure reduction adjustment valve 61B is the pressure reduction adjustment valve 61A.
It has a smaller Nikkei and is configured to be suitable for controlling a small flow rate. The intake pipe 73 is provided with an intake valve 74 that is opened when a pressure reduction control system, which will be described later, is operated. Here, the vacuum source 80 consists of the vacuum tank 35 and the vacuum pump 34, and the pressurization source 90 consists of the air tank 51 and the compressor 50.

A grog maple controller (hereinafter referred to as a controller) 100 calculates the difference from the pressure setting value based on the pressure detection signal from the pressure gauge 42, calculates the difference from P, and outputs the opening command signal and intake air of each regulating valve. Outputs opening/closing command signals for valves or pressurizing on/off valves. Further, as shown in FIG. 2, the controller is configured to perform continuous pressure control by combining two systems, a pressure reduction control system and a pressure control system. In other words, the adjustment/tube needle has a program built into it that automatically switches from the pressure reduction control system to the pressure control system or the opposite control system to the above according to changes in the pressure setting value. When the set value is varied, the difference between the pressure set value and the detected pressure value is immediately calculated from P, while
The optimal control system is selected from the detected pressure values. Then, a command signal is outputted from P to a control means such as a regulating valve belonging to the control system selected based on the result of the calculation.

Next, the operation of the above embodiment will be explained.

First, when operating the pressure reduction control system, the auxiliary pressure reduction adjustment valve 61B
Then, the pressurizing on-off valve 72 is fully closed, and the intake valve 74 is fully open. Then, when the pressure setting value corresponding to the desired tank pressure is set in the programmable controller, the controller 100
is the pressure setting value P.

and the pressure detection value P1 from the pressure gauge 42 (P.

-Po) is subjected to PID calculation, and (Pt-”a) > O
When (Pt-Po) (0), a command signal is output to control the opening degree of the pressure-reducing regulating valve 61A. The pressure adjustment tank 33 is evacuated by controlling the opening degree of the tank.

The pressure in the tank is reduced, and the pressure inside the tank is adjusted to reduce the pressure.
By controlling the opening degree of the pressure adjustment valve 71A, atmospheric air is supplied to the pressure adjustment tank 33 and the tank pressure is increased.
When operating the zero pressurization control system that increases and adjusts the tank internal pressure, the pressure reduction adjustment valve 61A and the intake valve 74 are fully opened, and the pressurization on-off valve 72 is fully opened. This pressurization control system can control a pressure range ranging from a negative pressure region below the tank internal pressure to a positive pressure region above the tank internal pressure at the atmospheric pressure of the pressure adjustment 3-3.

When a pressure setting value corresponding to a desired tank pressure is set in the controller 100, the controller 100 calculates the difference (Pl - Po
) from P, and when (Ps-Po)>00, outputs a command signal to control the opening degree of the auxiliary pressure reduction regulating valve 61B,
On the other hand, when (Ps-Po)<O, the pressure regulating valve 71A
Outputs a command signal to control the opening of N. By controlling the opening degree of this auxiliary pressure reduction adjustment valve 61B, the discharge of air from the pressure adjustment tank 33 is accurately controlled to lower the tank pressure and adjust the tank internal pressure. Automatic switching between a zero depressurization control system and a pressurization control system that supplies compressed air from the air tank 51 to the pressure adjustment tank 33 to raise and adjust the tank pressure by controlling the opening degree of the tank. When driving,
Each regulating valve, pressurizing on-off valve, intake air, etc. are controlled according to the difference between the pressure setting value and the pressure detection value and the changing pressure setting value.

For example, change the pressure inside the tank to the pressure within the control range of the pressure reduction control system (
When conducting an experiment in which the pressure is continuously variable controlled from (lower limit value) to a pressure within the control range of the pressurization control system (lower limit value), the depressurization control system is first selected. In this pressure reduction control system, the auxiliary pressure reduction adjustment valve and the pressurization adjustment valve are closed, and the pressure reduction adjustment valve 61A is closed.
When the pressure adjustment valve 61A and the pressure adjustment valve γ are opened, the pressure adjustment tank 33 is evacuated, the tank pressure is lowered, and the pressure inside the tank is reduced.
The pressure is maintained at the lower limit by controlling the opening of the IA.

Then, when the C1 pressure set value is continuously changed toward increasing pressure, this pressure set value and the detected pressure value are finally compared and a difference is determined. This difference is immediately subjected to PID calculation, and at the same time, a pressure reduction control system is selected from the detected pressure value. Subsequently, a pressure adjustment valve opening command signal is output based on the result of the PID calculation, and the intake valve 74 and the pressure adjustment valve 71
Atmospheric air is supplied to the pressure adjustment tank 33 through A, and the tank pressure is increased to increase and adjust the pressure inside the tank. Since this process is performed to follow changes in the pressure setting value, the internal pressure is continuously increased and adjusted. After that, the pressure inside the tank increases and the pressure control region (0,895 to 0.900 bar) where the pressure reduction control system and the pressure adjustment system overlap
), the pressurization control system is selected under predetermined conditions, the pressure reduction adjustment valve, auxiliary pressure reduction adjustment valve, and intake valve are closed, and the pressurization on-off valve is opened. Subsequently, the pressure inside the tank is continuously controlled toward the upper limit pressure set under the pressurization control system. In other words, in the pressurization control system, like the pressure reduction control system, the opening of the pressure adjustment valve is controlled to follow the changing pressure setting value, and compressed air from the air tank is supplied to the pressure adjustment tank. Ru. Then, the tank pressure increases, and the internal pressure in 4 is adjusted accordingly. Thereafter, when the internal pressure in the tank reaches the set upper limit pressure, the pressure adjustment valve is closed and the experiment ends.

In addition, in the explanation of the operation of the above embodiment, the control for changing the tank internal pressure from low to high was described, but the reverse operation is also possible. Moreover, although pressure control that spans two systems, the pressure reduction control system and the pressurization control system, has been described, variable pressure control within the same control system is also possible.

〔Effect of the invention〕

As described above, according to the present invention, atmospheric air is used to adjust the pressure increase in the pressure reduction control system, and the flow rate of this atmospheric air is controlled by the pressure adjustment valve, so that the negative pressure region in the pressure reduction control system is controlled. Easy to control υ, it is possible to accurately control a wide range of tank pressures, including the tank pressure at standard atmospheric pressure, and it is built into the controller! The program enables continuous pressure control in the pressure range by combining the depressurization control system and the pressurization control system, expanding the range of experimental applications and making efficient use of the cavitation water tank.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a pressure control device for a cavitation water tank according to the present invention, Fig. 2 is a relationship diagram between set pressure and pressure in the tank, and Fig. 3 is a pressure mlj of a conventional cavitation water tank.
FIG. 2 is a configuration diagram showing a control device. 21... Cavitation water tank, 33... Pressure adjustment tank, 61... Pressure adjustment means, 71... Pressure adjustment means, 72... Pressurization on/off valve, 74... Intake valve, 100. ...Programmable adjustment meter. ■ Ya62 Kako 3

Claims (1)

[Claims] A pressure adjustment tank is connected to the circulation flow path, a pressure adjustment mechanism is provided in the pressure adjustment tank, and the pressure adjustment mechanism is operated based on the pressure of a measurement section of the circulation flow path to control the pressure of the pressure adjustment tank. In a pressure control device for a cavitation water tank that adjusts the pressure inside the tank, a vacuum source is connected to the pressure adjustment tank via a pressure reduction adjustment means, and a pressure source is connected to the pressure adjustment means via a pressure adjustment means, and the pressure adjustment means and A pressurization on-off valve is interposed between the pressurization source and an intake pipe having an intake valve and open to the atmosphere is connected to the pipe line between the pressurization adjustment means and the pressurization on-off valve, and the The pressure adjustment mechanism includes a controller that controls each adjustment means and each valve based on the detected pressure of the measuring section, and the controller reduces the pressure in the pressure adjustment tank by operating the pressure reduction adjustment means. , and a pressure reduction control system that introduces atmospheric air and raises the pressure by operating the pressure adjustment means and adjusts the pressure inside the tank, and a pressure reduction control system that adjusts the pressure in the pressure adjustment tank by introducing compressed air from the pressurized source by operating the pressure adjustment means. is supplied to increase the pressure, and reduce the pressure by operating a pressure reduction adjustment means,
A cavitation system configured to allow independent operation using either one of the pressurization control systems that adjusts the pressure inside the tank, and automatic switching operation that continuously varies the pressure inside the tank by combining both control systems. Aquarium pressure control device.