JPH0667733A - Liquid level control system - Google Patents

Abstract

PURPOSE:To compactly constitute the whole device, to prevent a malfunction and to prevent wear by controlling a mechanical liquid level control system formed by combining a self-actuated type automatic valve and a float valve by an electronic circuit by using a power-actuated type automatic valve and a liquid level switch. CONSTITUTION:The system is constituted so that as for power-actuated type automatic valves 22, 24, a motor-driven valve is used, and in liquid level switches 41, 42 and 43, even if chattering caused by inflow water is generated, a timer for preventing it is provided in a control circuit.

Description

Detailed Description of the Invention

[0001]

The present invention relates to building equipment, agricultural equipment,
The present invention relates to a control system used for liquid level control of a liquid storage tank provided in irrigation equipment, factory equipment and the like.

This is a liquid level control system in which a manual force type automatic valve and a liquid level switch are combined, and a timer prevents frequent switching of an electric circuit due to chattering of the level switch due to ripples.

[0003]

2. Description of the Related Art A conventional liquid level control in a liquid storage tank is shown in FIG.
As shown in FIG. 11, it is composed of a self-powered automatic valve 2 provided on the upper part of the liquid storage tank 1, a float valve 3 for controlling it, and an electrode 4 for a liquid level switch. As the fluid is used from the outflow pipe 6 and the liquid level 5 is lowered, the float 31 is lowered and the valve of the float valve 3 is opened and the fluid flows into the liquid storage tank 1 through the pilot pipe 9 branched from the inflow pipe 8. . As a result, the internal pressure of the pilot pipe 9 is lowered, and the internal pressure of the cylinder portion 21 of the self-powered automatic valve 2 connected thereto is also lowered to push up the valve body 22 by the inflow pressure of the inflow pipe 8 and the fluid is stored in the liquid storage tank. Start the inflow.

When the fluid is filled up to the specified position in the liquid storage tank, the float 31 rises and the valve of the float valve 3 is closed, so that the fluid pressure in the pilot pipe 9 rises and the internal pressure of the cylinder portion 21 of the self-powered automatic valve 2 increases. The pressure rises to push down the valve element 22 to stop the fluid from flowing into the liquid storage tank. The electrode 4 issues an alarm when the self-powered automatic valve 2 and the float valve 3 for controlling the automatic valve 2 fail and the liquid level becomes abnormally high or low, and controls the operation of the valve. is not.

[0005]

In the conventional method having the above-described structure, the self-powered automatic valve 2 and the float valve 3 for controlling the self-operated automatic valve 2 are mechanically operated by the float and the fluid pressure, and therefore wear is caused. It often happens that malfunction occurs due to adhesion of scales or the like, and water hammer of the self-powered automatic valve 2 also occurs due to rapid opening and closing of the float valve 3. Some pilot pipes 9 and cylinders 21 incorporate a throttle valve for preventing water hammer, but malfunctions occur when foreign matter is clogged, which requires regular maintenance.

Further, since the scale is attached to the electrode 4 to cause poor electrical continuity, regular maintenance is required. In order to prevent the float 31 from chattering due to the corrugation of the fluid flowing from the inflow pipe 8, it is necessary to install the wave preventing plate 10. Further, the position where the self-powered automatic valve 2 is attached must always be provided above the liquid storage tank 1 as shown in FIG.
When the liquid storage tank 1 is installed in a place with an underground tank or a ceiling, it takes a lot of man-hours to lift and attach a heavy object to a high place.

[0007]

FIG. 1 shows a system invented as a means for solving the above problems. First, the self-powered automatic valve 2 is replaced with the other-powered automatic valves 23 and 24. Power source O for the type of other force type automatic valve
An electric valve 23 that shuts off the flow path by an FF and an electric valve 24 that opens and closes by a signal input are used. For the liquid level switch,
A proximity switch or a Hall element, which operates by magnetic force, is mounted inside the pipe, and a method of detecting the liquid level with a float equipped with a magnet is used to prevent malfunction due to scale adhesion of the electrode 4. Moreover, since the electrode 4 using the electrode 4 has a voltage of 12 V, 24 V, etc. applied to the electrode 4, it cannot be used for a combustible fluid such as kerosene or gasoline, but it is a proximity switch or hall element that operates by the magnetic force of the present invention. Because of the intrinsically safe explosion-proof structure, it can be used for combustible fluids such as kerosene and gasoline. Regarding chattering of the liquid level switch due to waving of the fluid flowing in from the inflow pipe 8, this is not suppressed, but electricity is interrupted by a timer provided in the electric circuit while chattering occurs, This means that the switch is activated when the liquid level is not affected by the corrugation on the upper surface or the lower surface of the liquid level switch.

[0008]

The operation of controlling the liquid surface by the above means is as follows. Since the fluid is used from the outflow pipe 6 and the liquid level 5 is lowered, the constant liquid level switch 42 of the liquid level switch
Turns on or off. As a result, the motor-operated valve 24 that opens and closes in response to the signal input opens, and the fluid flows into the liquid storage tank 1 through the inflow pipe 8. When the liquid level in the liquid storage tank 1 rises, the constant liquid level switch 42 is turned off or on, and the electric valve 24 that opens and closes by signal input is closed. If a power failure occurs while the electric valve 24 is open, the constant liquid level switch 42
Cannot output an OFF or ON signal,
The motor-operated valve 24 remains open and the fluid flows into the liquid storage tank 1 indefinitely. In order to prevent this, power supply O
A motor-operated valve 23 that shuts off the flow path by the FF is installed in the inflow pipe 8.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the liquid level control system according to the present invention will be described with reference to the drawings. FIG. 1 shows the entire system of the present invention. The inflow pipe 8 to the liquid storage tank 1 is provided with an electric valve 23 that shuts off the flow path when the power is turned off such as during a power failure and an electric valve 24 that opens and closes by a signal input, as an example of another force automatic valve. The motor-operated valve 24 that opens and closes by the signal input by turning on and off the constant liquid level switch 42 of the liquid level switch operates to perform liquid level control. Reference numeral 15 is a control unit having a function of issuing an alarm from the signals of the low liquid level switch 43, the full liquid level switch 41, etc., and transmitting the signal of the constant liquid level switch 42 to the motor-operated valve 24. Reference numeral 6 denotes an outflow pipe, which is an outlet of the liquid storage tank 1.

With the above-mentioned structure, the operation thereof will be described. When the fluid is used from the outflow pipe 6 and the liquid level 5 is lowered, the constant liquid level switch 42 of the liquid level switch becomes O.
N or OFF. As a result, the motor-operated valve 24 that opens and closes in response to the signal input opens, and the fluid flows into the liquid storage tank 1 through the inflow pipe 8. When the liquid level in the liquid storage tank 1 rises due to the inflow, the constant liquid level switch 42 is turned off or on, and the electric valve 24 that opens and closes by a signal input is closed. If a power failure occurs while the electric valve 24 is open, the constant liquid level switch 42
Cannot output an OFF or ON signal,
The motor-operated valve 24 remains open and the fluid flows into the liquid storage tank 1 indefinitely. In order to prevent this, power supply O
An electric valve 23 that shuts off the flow path by the FF is installed in the inflow pipe 8, and the electric valve 23 is closed at the same time as the power failure.

The motor-operated valve 23 that shuts off the flow path when the power is turned off, such as during a power failure, is generally called a spring return valve. When the power is turned on, the motor built in the actuator winds the spring to open the valve. When the power is turned off, the valve is closed by the force of the spring. In addition to this, the motor built into the actuator is a DC motor, and it is usually used as an electric valve that opens and closes by a power source that uses a commercial power supply AC 100 V or 200 V as a DC by a rectifier, and immediately switches to the battery and shuts off in the event of a power failure. In that case, the motor-operated valve 24 that opens and closes by signal input may be omitted, and only one motor-operated valve 23 that shuts off the flow path by turning off the power supply during a power failure may be used.

FIG. 2 shows an embodiment of another force type automatic valve. An actuator 23A that shuts off the flow path when the power is turned off at the time of power failure and an actuator 24A that opens and closes by a signal input are assembled in one valve box 25. FIG. 3 is an external perspective view of an automatic valve for a liquid level control system, and FIG. 3 is a partial front sectional view of FIG. As shown in FIG. 1, space and size can be reduced as compared with the case where the motor-operated valves 23 and 24 are individually piped, and at the same time, the piping work is also labor-saving.

Next, as the liquid level switches indicated by the full liquid level switch 41, the constant liquid level switch 42, and the low liquid level switch 43 in FIG. 1, those using a proximity switch operated by magnetic force are illustrated. This switch has the structure shown in FIG. 4, and when the proximity switch 411 built in the pipe 410 is excited by the magnetic force of the magnet 412 built in the float 413, its contact 415 is closed and the float 413 comes close. switch
Open contact 415 when away from 411. Since the contacts are completely sealed in this way, pipe 41
Even if water stains 416 adhere to the outer circumference of 0 or the float 413, there is no possibility of electrical continuity failure like the electrodes, and there is no need for regular maintenance. 414 is a stopper of the float 413.

FIG. 5 shows an embodiment in which the liquid level switch shown in FIG. 4 is attached to each of a full liquid position 41, a constant liquid position 42 and a low liquid position 43. 44 is a float base and a gasket for fixing the liquid level switch to the pipe 45.
It is fixed to the liquid storage tank 1 with a flange 47 via 46. 48
Is a connector for fixing the cable of the liquid level switch. 49 is a hole for adjusting the upper and lower positions of the liquid level switch. When it is not necessary to adjust the vertical position of the liquid level switch, the pipe 410 is extended and the liquid level switches are arranged at three internal positions as shown in FIG. Further, as shown in FIG. 7, the proximity switch 411 and the magnet 412 are connected to the float 42.
The effect of the present invention does not change even if the system is built in 2 and is suspended on the liquid surface 5 by the weight 421.

FIG. 8 shows a control circuit according to the present invention. Normally, the constant liquid level control circuit 426 which receives the ON-OFF signal of the constant liquid level switch 42 is operated by a timer function for preventing chattering, and the motor operated valve 24 is operated. Is operated to control the liquid level. When the power supply 440 is turned off due to a power failure or the like, the electric power of the entire control circuit is lost, so that the motor-operated valve 23 is shut off. 441 is a rectifier circuit, which is a commercial power AC100V or 200V
Is converted to DC and the voltage flowing to the liquid level switch is 12V
We are trying to improve safety by making the voltage as low as possible. 416
, 436 are full liquid level detection circuit and low liquid level detection circuit,
It has a built-in timer to prevent chattering of the liquid level switch. 417 and 437 are full liquid level output contacts and low liquid level output contacts that can be used as contacts for activating the standby pump or closing the emergency shutoff valve when an abnormal liquid level is reached. 442
Can be used as a contact for generating an abnormality with a buzzer alarm or lamp display.

FIG. 9 shows an embodiment of a timer incorporated in the liquid level detection circuits 416, 426 and 436.
The time when 42,43 chattering occurs 151,152
It is set by changing the resistance value of and the capacitance of the capacitor of 153. Reference numeral 154 is a relay for opening and closing the electric actuator 24A of AC 100V, 200V by the change of the voltage of the liquid level switch of about DC 12V. The type of the timer is not limited to this, and the effect of the present invention is the same whether it is a mechanical timer or a pneumatic timer.

FIG. 10 shows a motor-operated valve 23 that shuts off the flow path when the power is turned off such as during a power failure and a motor-operated valve that opens and closes by a signal input
24 is unitized with pipes 241 and this is a casing
It is fixed to 243, and the electric circuit shown in FIGS. 8 and 9 is assembled on the operation panel 244 at the upper part, and it includes the control circuit of 245, the terminal block of 246, the transformer of 247, the power switch of 248, etc. Has been. In this way, the external force type automatic valve and the control unit 15 are housed in one casing 243, so that the piping and wiring can be simplified and the installation space can be reduced as compared with the separately installed type shown in FIG.

As described above, according to the liquid level control system of the present invention, the following effects are obtained. (1) Since the conventional self-powered automatic valve is a ball valve type because of its structure, the pressure loss of the fluid is large, but the ball valve type valve can be used in the other force type automatic valve of the present invention. The pressure loss of the fluid is small. Therefore, an automatic valve smaller than the conventional self-powered automatic valve by one size or more can be adopted. This is economical as it not only reduces installation costs but also reduces water bills. (2) According to the present invention, since the valve is opened and closed by an electronic circuit having no mechanical portion, the float valve is small in size and light-weight without wear and scale malfunction. (3) Even if chattering occurs in the liquid level switch due to inflow water, it is not necessary to attach a wave breaker to prevent chattering, and construction costs can be reduced.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional external view showing the configuration of the entire liquid level control system of the present invention.

FIG. 2 is an external perspective view showing an example of the other force type automatic valve used in the liquid surface control system of the present invention.

3 is a partial cross-sectional front view of FIG.

FIG. 4 is a partial cross-sectional front view showing an example of the liquid level switch used in the present invention.

5 is an external perspective view showing an example of a case where the liquid level switch shown in FIG. 4 is set to be positionally adjustable.

FIG. 6 is an external view showing an example of a case where a proximity switch is built in a pipe.

FIG. 7 is an external view showing an example of a proximity switch built in a float.

FIG. 8 is a control circuit diagram of the entire liquid level control system showing an example of the present invention.

FIG. 9 is an electronic circuit diagram for preventing chattering of the liquid level switch.

FIG. 10 is an external view showing an example of the case where the other force type automatic valve and the control unit are housed in one casing.

FIG. 11 is a cross-sectional view showing the overall configuration of a conventional liquid level control system.

[Explanation of symbols]

 1 ... Reservoir tank 15 ... Control unit 151, 152, 153 ... Timer 23, 24 ... Other-powered automatic valve 23 ... Motorized valve that shuts off the flow path when the power is turned off 23A ... Actuator 24 that shuts off the flow path when the power is turned off Motor operated valve 24A that opens and closes by signal input ... Actuator that opens and closes by signal input 243 ... Casing 25 ... One valve box 41, 42, 43 ... Liquid level switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Mizuki 1-23-35 Nanogawa, Minami-ku, Fukuoka-shi, Fukuoka Kyudenko Corporation (72) Inventor Toshiyuki Kunisaki 8th Akasaka coast, Kokurakita-ku, Kitakyushu, Fukuoka No. 20 In Fuji Kiko Co., Ltd. (72) Inventor Mochi Maeda 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Hitachi Metals Co., Ltd. (72) Inventor Nagabari 200 Komukai, Asahi-cho, Mie-gun, Mie Prefecture Hitachi Valve Incorporated (72) Inventor Norio Teramoto 200 Komukai, Asahi-cho, Mie-gun, Mie Hitachi Valve Co., Ltd.

Claims (5)

[Claims] 1. In the liquid level control of a liquid storage tank using another force type automatic valve and a liquid level switch, the other force type automatic valve is opened / closed by an electric valve for shutting off the flow passage by turning off the power source and a signal input. A liquid level control system characterized in that the motorized valves for performing the above are separately used and combined with the liquid level switch. 2. In the liquid level control of a liquid storage tank using another force type automatic valve and a liquid level switch, the other force type automatic valve has a function of opening and closing by a signal input and a power source O in case of power failure.
A liquid level control system characterized by combining one motor-operated valve having a function of blocking a flow path by an FF and the liquid level switch. 3. An actuator that shuts off the flow path when the power is turned off and an actuator that opens and closes when a signal is input are assembled in one valve box.
Or the liquid level control system according to 2. 4. A liquid level control system, characterized in that a timer prevents frequent on / off of an electric circuit due to chattering of the liquid level switch. 5. A liquid level control system, wherein the other force type automatic valve and the control unit are housed in one casing.