JPS5816129B2 - exhaust equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention controls a liquid level detector to follow a liquid level that changes up and down, and calculates a value obtained by defining a mechanical change in the up and down movement accompanying the tracking as an amount of change in the liquid level. (Analog quantity or digital quantity by analog-digital conversion)
The present invention relates to a liquid level detection device for a liquid level needle for measuring liquid level with high precision.

In general, various methods for detecting water level are used, such as those using mechanical floats, differential pressure, sound waves, etc., but all of these methods have large detection errors due to changes in water level and are highly accurate. (for example, ±Q, 5 mm or less).

Also, among the above methods, there is a float method that is relatively accurate, but since this also uses buoyancy, it is extremely difficult to set the width of the dead zone to less than ±1 mm. .

Furthermore, as a method other than the above-mentioned methods, there is a liquid column method that can obtain relatively high precision, but since this method relies on visual detection, it is dependent on human labor, and it is difficult to extract electrical signals. As it is, it is in a poor state.

Therefore, as a means using this liquid column, automation and unmanned operation for labor saving cannot be expected.

Therefore, the present invention aims to provide a detection device for detecting the amount of change in liquid level with a configuration unprecedented in the past, in order to eliminate the inconveniences in the above-mentioned uses and improve the accuracy of measurement. .

The details will be explained with reference to an example shown in a male diagram.
2 is the measurement side electrode for detecting the increase/decrease in the liquid level, and 2 is the
This is a short side electrode serving the same purpose as above.

The long side electrode 1 and the short side electrode 2 have their upper ends fixed to an insulating support 3 in a parallel state, and each of the electrodes 1, 2
It is arranged so that it faces the inside of the tank 4 into which the liquid to be measured is supplied, with a dimensional difference of t between the lower ends of the .

Moreover, a common electrode 5 is provided inside this tank 4,
Between this common electrode 5 and each of the long and short electrodes 1 and 2,
When the amount of liquid to be detected increases and comes into contact with each electrode 1 or 2, the resistance value Rw between the electrode and the common electrode 5 decreases, and increases significantly when the liquid is separated from the electrode.

Note that the liquid to be detected here refers to a conductive liquid such as water.

The support body 3 provided with the electrodes 1 and 2 described above is screwed onto a vertical screw shaft 7 whose drive source is a servo motor 6 which is rotated by a signal to be described later. It is designed to move up and down accordingly.

Further, reference numeral 8 in the figure denotes a guide shaft provided parallel to the screw shaft γ between the upper and lower ends of the frame 9 on which the upper and lower ends of the screw shaft γ are rotatably supported. When the support body 3 moves up and down,
This is a steady stop that prevents the support body 3 from swinging, and allows the support body 3 to move up and down smoothly.

The amount of vertical movement of the support body 3 is determined by the rotation angle of the servo motor 6 and the pitch of the screw formed on the screw shaft 7.

Next, a servo system is used to extract the output according to the change in the resistance value Rw between each of the electrodes 1 and 2 and the common electrode 5, and to operate each electrode 1 and 2 proportionally in the direction of increase or decrease of the liquid level using the output. The configuration will be explained.

First, to take out the output due to the change in resistance value Rw, connect one AC output terminal of the oscillator 10 that generates AC with a predetermined frequency to the long side electrode 1 and short side electrode 2. , insert high resistances R1 and R3 between the respective connections, and connect the other AC output terminal to the common electrode 5 to connect the high resistances R1 and R2 to each connection point of each electrode 1, 2. h□, R2 to each comparison circuit (operational amplifier, etc.) IC1
3, and each of the comparator circuits 1
1° and 12 non-inverting input terminals t1. Variable resistors R3 and R4 for setting a predetermined threshold level ESI j ES2 are connected to t2, and their respective non-inverting input terminals t1
．． Level ESt or ES2 occurring at point t2 and resistance value R
This constitutes a comparison section for comparing the voltage with the change in w.

A monostable circuit (one shot) 13.14 is configured on each output side of the comparison circuits 11.12, and outputs ml of either of the comparison circuits 11, 12.

The pulse-like signal P1 generated at rη2 is converted into a signal P2 having a constant voltage level.

Furthermore, two sets of AND gates 1-15 and 16 are provided on the output side of the monostable circuits 13 and 14, and the input side of one of the AND gates 15 receives the signals of the monostable circuits 13 and 14. The inverted signals are inserted into the inverter circuits 11 and 18, and the monostable circuits 13 and 14 are inserted into the AND gate 16.
The signal is inserted.

That is, the output from the AND gates 15 and 16 with the above circuit configuration is an up signal UP for raising the support 3 from the AND gate 15 when both the electrodes 1 and 2 are in contact with the liquid surface. When the electrodes 1 and 2 move away from the liquid level, the AND gate 16 outputs a down signal DU to lower the support 3.

Reference numeral 19.20 denotes an amplifier which amplifies each output signal UP or DU from each of the AND gates 15 and 16 and uses it as a command signal for forward or reverse rotation of the servo motor 6.

21 is a potentiometer for obtaining an output for remote control that rotates in conjunction with the servo motor 6;
is a display board.

The present invention has the above configuration, and its operation will be explained next.

Now, when the liquid level in the tank 4 rises and comes into contact with the long side electrode 1,
The resistance value Rw between the long side electrode 1 and the common electrode 5 is reduced.

In that case, the voltage at the inverting input terminal h1 of the comparator circuit 11 decreases due to the relationship of output EpC and Ep In comparison with ES1, through the comparison circuit 11,
As shown in the following formula, E S I > E p X',
From the relationship Rw 1□, the voltage of the output m1 becomes \R1+Rw -vb, and the monostable circuit 13 is not triggered, so the voltage of the output n1 of the monostable circuit 13 becomes Ov.

Also, when the short side electrode 2 is in contact with the liquid surface, Rw Similarly to the above, the comparator circuit 12
The voltage at the inverting input terminal h2 of the comparator circuit w12 decreases, and the voltage at the output m2 of the comparator circuit w12 becomes E, 2〉EpX R2+Rw
At -vb, the voltage of the output n2 becomes OV.

Therefore, as described above, the output n 1 of the monostable circuits 13 and 14
+ When each voltage of R2 becomes Ov, each inverter 17
．． An up signal UP is output from the AND gate 15 inputted through the amplifier 18, and the voltage amplified through the amplifier 19 is used to drive the servo motor 6, so that the short electrode 2 is lower than the liquid level. The support body 3 will be raised until it is separated.

At the same time, the potentiometer 21 rotates, and a control signal to the outside is obtained by the change in resistance.

Next, when the short side electrode 2 and the liquid surface separate from each other, contrary to the above operation, the resistance value Rw between that electrode 2 and the common electrode 5 increases significantly, and the voltage of the output w m2 of the comparator circuit 12 becomes E8□ From the relationship of EpX R2+Rw,
+Va, the monostable circuit 14 is triggered as shown in FIG. 2, and the output n is a signal P2 of +Vc.

Moreover, when the liquid level further falls by the dimension t from the operating point and the distance between the long side electrode 1 and the liquid surface becomes distant, the voltage at the output point 01 of the monostable circuit 13 also becomes 10 V e due to the same effect as described above. , the down signal DO is output from the AND gate 16,
The servo motor 6 is driven in the opposite direction to the above-mentioned direction by the amplification signal via the amplification device 20 until the electrode 1 comes into contact with the liquid level by lowering the support 3 that engages with the screw shaft T. .

At the same time, the potentiometer 21 also rotates and the resistance value changes.

Next, to explain the means for adjusting the measurement accuracy, from the above explanation of the operation, the rising signal is generated only when both the long side electrode 1 and the short side electrode 2 are in contact with the liquid level or when they are separated from the liquid level. U
Since either the signal P or the descending signal DU is output, by setting the difference in the length dimension t between the two electrodes 1 and 2 to be short, the sensitivity to changes in the liquid level can be improved. , the sensitivity deteriorates by increasing the dimension t of the correspondence.

Therefore, under conditions with few liquid level fluctuations, this dimension t can be set within 0.5 m, and the liquid level measurement error is ±
It can be within 0.5 mm.

As described above, the present invention provides a pair of electrodes 1 and 2 having different lengths.
Detects changes in the liquid level depending on whether it comes into contact with the liquid level or when it leaves , each electrode 1
, 2, and the servo system is configured to switch and control the rotational direction of the servo motor 6 so as to rotate the liquid level, and to output an analog value corresponding to the increase/decrease in the liquid level through a potentiometer; In contrast, each electrode 1 and 2 can be tracked with good accuracy.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram showing one embodiment of the present invention, and FIG. 2 is a control waveform diagram in the same circuit. DESCRIPTION OF SYMBOLS 1... Long side electrode, 2... Short side electrode, 3... Support, 4... Tank, 5...
Common electrode, 6... Servo motor, 7...
・Screw shaft, 8...Guide shaft, 9...Frame,
10...Oscillator, 11,12...
Comparison circuit, 13.14... Monostable circuit, 15,
16...and gate, 17.18...
・・Inverter, 19゜20・・・・Mampler, 21
・・・・・・Potentiometer, R1, R2・・・・・・
・High resistance, R3, R4...variable resistance.

Claims (1)

[Claims] 1 A pair of electrodes with different lengths for detecting increases and decreases in the liquid level, a common electrode that penetrates into the liquid to be detected, and an oscillator for generating alternating current are provided, and one alternating current output terminal from the oscillator is connected to each of the above. Connect to the liquid level detection electrode through each high resistance, and connect the other AC output terminal to the common electrode, and connect or disconnect each electrode and the liquid level in response to changes in the liquid level. A liquid level detecting device characterized by comprising an output means for outputting a liquid level information signal that outputs a voltage difference based on a change in resistance between each electrode and a common electrode.