JPH08327434A - Water-level detection apparatus - Google Patents

Abstract

PURPOSE: To obtain a water-level detection apparatus which can sharply reduce the influence of scale or the like and detect a water level in all water qualities by a method wherein the electric resistance between the face of an electrode and water is sensed when the face of the electrode arranged in the position of a prescribed water level has reached the water level. CONSTITUTION: Electrode E1 to E6 (of which E4 , E5 and E6 are used for a lowest water level, a highest water level and a warning water level, respectively) are arranged in prescribed water level positions in a water tank 30. When a water level inside the water tank 30 reaches the level or higher of the electrode E4 , the electric resistance between the electrode E4 and water is changed, the output pulse width of a monostable multivibrator 25 triggered by an oscillator 24 becomes large, and a relay Ry4 at a judgment output circuit 26 is turned on. When a water level reaches the electrode E5 , relays Ry4 , Ry5 are operated, contacts Ry4-1a , Ry5-1a are turned on, a control relay X1 is turned on, and a submersible pump 31 discharges water by a self-holding circuit. When the water level is lowered to the level of the electrode E4 , the relay Ry4 is turned off, the self-holding circuit is stopped, and the pump 31 is stopped. Since the water level is detected on the basis of the electric resistance between the electrode and the water, the influence of an insulator such as scale or the like is reduced sharply even when the insulator is stuck to the face of the electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water level detecting device for detecting the water level in a water tank or the like, and more particularly to a water level detecting device capable of detecting the water level by one or several single electrodes having one electrode surface. It is about.

[0002]

2. Description of the Related Art <Conventional Water Level Detection Device 1> Conventionally, as a detection device for detecting the water level in a water tank, for example, a device as shown in FIG. 3 is known.

In FIG. 3, the water level detecting device has a power transformer (1) for stepping down a commercial AC power source, and two windings (2a) and (2b) are formed in its secondary winding. . Secondary winding
A diode bridge (3) is connected to one end of (2a), and a transistor (Tr1),
A switching circuit consisting of (Tr2) is connected. One end of the other secondary winding (2b) is directly connected to the electrode (5a) via the diode bridge (4), and the other end is connected to the electrode (5b) and is connected to the electrode (5b). It is inserted at intervals. The other end of the diode bridge (4) is connected to the base of the transistor (Tr1) via the resistor (R1) as a negative DC voltage via the capacitor (C2). Transistor (Tr
1) and (Tr2) are connected so that they turn on and off alternately, and a relay circuit (7) is connected to the collector of the transistor (Tr2).

As the electrode (5), for example, as shown in FIG. 4, the tip of a cylindrical case (8) is a cylindrical electrode (5a), the electrode (5b) is arranged at the center thereof, and these are made into resin. For example, an electrode formed by integrally molding is used.

If the water level of the water tank (6) does not reach the level of the electrodes (5a) and (5b), the negative voltage is not applied to the base of the transistor (Tr1), so that a positive predetermined voltage is applied. (Tr1) turns on and the transistor (T1
r2) is off and the relay circuit (7) connected to its collector does not work. However, the electrode (5
When the aquarium water level reaches the levels of a) and (5b), a negative voltage is applied to the base of the transistor (Tr1) via the diode bridge (4) and the transistor (Tr1) is turned off.
When (Tr2) is turned on, the relay circuit (7) is activated, and a child (not shown) can be activated.

<Conventional Water Level Detection Device 2> As another detection device for detecting the water level in the water tank, there is a device shown in FIG. 5 applied by the present applicant. The structure and working mechanism of the device of FIG. 5 are described in detail in Japanese Utility Model Publication No. 6-7328.

That is, in FIG. 5, the utility pole is provided with a pole transformer (11) for stepping down a commercial AC voltage of, for example, 6000V to a voltage of 100V. Pillar transformer (1
One end of the secondary side of 1) is grounded as shown in the figure in order to smoothly carry out maintenance and inspection of the transmission and distribution lines and to prevent high voltage from entering the home due to burning of the pole transformer. ing. Then, from the secondary side of the pole transformer (11), the power transformer (14) of the water level control device is connected via the outlet (12) and the plug (13). The power transformer (14) lowers the commercial AC power source to a low voltage, for example, 12V or 24V, and has a rectifier circuit (15) connected to the secondary side thereof to apply a DC voltage to each part of the water level detection device. To supply. Power transformer (14), rectifier circuit (15)
Configures a DC power supply circuit that rectifies a commercial AC power supply to obtain a predetermined power supply voltage.

In the water tank (16), a plurality of electrodes (E1) to (E3) are arranged at predetermined water levels. The electrode (E1) is the electrode placed at the lowest level of the water level to be retained, and the electrode (E1)
The detection circuit (17) is connected to 1) via a lead wire. The detection circuit (17) is a capacitor (C
3), has a resistor (R2), and the other end is connected to the base of the transistor (Tr3). The transistors (Tr3) and (Tr4) are connected in Darlington in order to increase the amplification factor and input impedance. And the transistor
The emitter of (Tr4) is grounded, and the capacitor (C4) is connected to the base of the transistor (Tr3). Further, the commonly connected collectors are connected to the positive terminal of the DC power supply via a collector resistor (R3). In addition, a resistor (R
The base of PNP transistor (Tr5) is connected via 4) and (R5), and the capacitor (C5) is connected to the common connection end and the positive end of resistors (R4) and (R5). Configure the circuit to prevent chattering. The transistor (Tr5) and the transistor (Tr6) are connected in Darlington connection, and the relay (Ry) is connected between the emitter of the transistor (Tr6) and the ground terminal.
1) is connected. Similar detection circuits (18) and (19) are connected to the other electrodes (E2) and (E3). Although detailed description of the configuration of these detection circuits (18) and (19) is omitted,
Relays (Ry2) and (Ry3) are connected respectively.

Now, the A contacts (Ry1-1) of the relays (Ry1), (Ry2)
Relay coils of a), (Ry2-1a) and control relay (X) are connected in series with the commercial AC power supply. A contact of relay (Ry2)
The A contact (X-3a) of the control relay (X) is connected in parallel to (Ry2-1a) to form a self-holding circuit. Control relay (X)
The pair of A contacts (X-1a), (X-2a) are connected between the terminals of the power source and supply power to the submersible pump (20) for drainage. The contact A (Ry3-1a) of the relay (Ry3) is connected to the buzzer (B) and energizes the buzzer when the warning water level is reached.

Next, the operation will be described. When the water level in the water tank (16) reaches or exceeds the level of the electrode (E1) as shown,
Secondary side of pole transformer (11) and ground, water tank (1
6), the water and electrodes (E1) in the aquarium (16) and the detection circuit (17), and the primary and secondary windings of the stray capacity between the primary and secondary windings and the secondary of the pole transformer (11). Since the windings are AC-coupled in this order, a leak current of a minute level, for example, about several μA flows from the commercial AC power supply.
This leakage current is a Darlington-connected transistor
It is amplified by (Tr3) and (Tr4). When the terminal voltage of the capacitor (C4) due to the leakage current, that is, the voltage between the base of the transistor (Tr3) and the emitter of the transistor (Tr4) becomes 1.5V or more, the transistors (Tr3), (Tr4) operate and the leakage current becomes The current is amplified by the product of the current amplification factors of these transistors, and the collector current flows through the transistor (Tr4). Therefore, the transistor (Tr5)
The base current also flows to 6) and the relay (Ry1) is energized.
At this time, current flows through the capacitor (C5) and the resistor (R4), and the capacitor (C5) is charged. Even if the water level drops and (Tr3) and (Tr4) turn off due to the charging voltage of the capacitor (C5), the relay turns off after a predetermined time delay.

Therefore, when the water level exceeds the level of the electrodes (E1) to (E3), the relays (Ry1) to (Ry3) are sequentially turned on. Therefore, when the water level rises and reaches the electrode (E2),
Since the relays (Ry1) and (Ry2) operate, their A contacts (Ry1-1
a), (Ry2-1a) are turned on and the control relay (X) is energized. Therefore, the submersible pump (20) operates while self-holding, and the water in the water tank (16) is drained.

Even if the water level drops below the level of the upper electrode (E2), the self-holding circuit keeps the control relay (X) on, so the submersible pump (20) continues to operate. . Now, if the water level further drops below the level of the electrode (E1), the relay (Ry1) is deactivated, the self-holding circuit stops, the control relay (X) turns off, and the submersible pump (2
0) stops. When the water level rises sharply and reaches the electrode (E3), the buzzer sounds to alert the alarm condition.

<Conventional water level detection device 3> In addition, as a detection device for detecting the water level in the water tank, a device using a float switch in which a mercury switch or the like is enclosed in order to detect a predetermined level in the water tank is also available. Are known.
This is to detect the water level at a predetermined level by conducting a mercury switch or the like inside the float switch based on a change in the inclination of the float switch that floats on the water surface as the water level rises.

[0014]

[Problems to be Solved by the Invention]

<Problems of Conventional Water Level Detector 1> According to the water level detectors shown in FIGS. 3 and 4, two electrodes (5a) and (5b) are used as electrodes.
It is necessary to face each other and insert them at the same water level.
And because the resistance of water in the water tank (6) is large, and because it is operated at a low voltage (for example, 12V or 24V), the distance between the electrodes cannot be increased so much (50 mm or less). If water stains adhere to the surface of the electrodes or sticky suspended matter adheres between the electrodes, the influence of the adhesion is large because the operation is performed at a low voltage, and the water level reaches the electrodes (5a), (5b). There is a drawback that it may malfunction regardless of whether or not it is present, that is, regardless of the level of the water level. As described above, the adhesion of water stains and sticky suspended matter has a great influence on the detection of the water level, and therefore it is necessary to regularly clean or replace the electrodes. In addition, there are drawbacks in that sensitivity adjustment is performed depending on the quality of water such as purified water, salt water, sewage, and chemical water, and various types of electrodes are required.

<Problems of the conventional water level detecting device 2> On the other hand, according to the water level detecting device shown in FIG. 5, it is not necessary to form electrodes facing each other as electrodes, and an electrode having one electrode surface. Since it detects the weak leak current by itself and detects the water level, it has high sensitivity, less influence of scale and sticky suspended matter, and can detect the water level of any water quality.

However, in this water level detection device, the polarity of the secondary AC grounding side of the pole transformer (11), that is, the polarity of the commercial AC power source, changes depending on the insertion direction of the plug (13) connected to the outlet (12). However, there is a drawback that the sensitivity changes because the magnitude of the leak current changes.

Generally, since the water tank is considered to be electrically grounded, a weak leak current flowing through the ground can be detected. However, a water tank made of an insulating material such as plastic is electrically connected to the ground. Since it is insulated from, the leak current cannot be detected. Therefore, the above water level detection device has a drawback that it cannot be applied to the water level detection of a water tank or the like made of an insulating material.

In addition, when a generator is used as a power source, one side is not grounded unlike a commercial AC power source, so that it is electrically insulated from the ground, leak current cannot be detected, and water level cannot be detected. There was a flaw.

As described above, the conventional water level detecting device 2 overcomes the problems of the conventional water level detecting device 1, but there is room for further improvement for practical use.

<Problems of the conventional water level detecting device 3> In a device for detecting the water level by a float switch using a mercury switch or the like, not only the shape of the float switch becomes large, but also the adhesive floating matter on the float. May adhere to the float and increase the weight of the float, resulting in an unclear detection level and causing a malfunction. In addition, there is a drawback that malfunctions due to contact failure of the mercury switch and mercury contamination due to breakage of the float switch are likely to occur.

<Purpose of the Present Invention> The present invention has been made in order to fundamentally overcome the problems of the conventional water level detection devices 1, 2 and 3, and is filed by the present applicant. By further greatly improving the above-mentioned water level detection device 2 mechanically, it is possible to significantly reduce the effects caused by adhesion of scales and sticky suspended matter, and to accurately perform water level detection of all water qualities. Further, it is an object of the present invention to provide a versatile water level detection device which can be applied to a water tank made of an insulating material such as plastic and further applicable to the case where a generator is used as a power source. To do.

[0022]

The water level detecting device of the present invention is a water level detecting device for detecting the water level in a water tank or the like, and is arranged at a predetermined water level in the water tank or the like and has one electrode surface. An electrode and a detection circuit for detecting and controlling the water level by sensing the electric resistance or capacitance between the electrode and water when the water surface such as a water tank reaches the water level where the electrode is arranged. It is a feature. (Here, "or" of "electrical resistance or capacitance" is a concept including "and".)

In the present invention, an electrode having one electrode surface is used. FIG. 2 is a sectional view showing an example of an electrode having one such electrode surface.

In FIG. 2, reference numeral (32) is a cable. Reference numeral (33) is a case, which is formed of a plastic molded product such as polyvinyl chloride. (34) is an electrode surface, which is made of any conductive material, but stainless steel having a large specific gravity is preferable in order to surely sink it in water. (35) is a cap, which may be formed of the same material as the electrode (34) (in this case, the cap (35) may be integrated with the electrode (34)) or has conductivity. It can also be formed of a material that does not. (36) is an electronic circuit, and (37) is a molding resin such as an epoxy resin.

Further, in the present invention, when the water surface of the water tank (30) or the like reaches the water level where the above-mentioned electrode is arranged, the electric resistance or electrostatic capacity between the electrode and water is sensed to detect the water level. A detection circuit for detecting and controlling is provided. Details of the detection circuit will be described in an embodiment described later.

[0026]

In the water level detecting device of the present invention, an electrode having one electrode surface is arranged at a predetermined water level in a water tank or the like. When the water level reaches the electrode surface, the electric resistance or capacitance between the electrode surface and water is sensed, and the level is detected to detect that the water level has reached the electrode position. I have to.

In the present invention employing such a mechanism, it is not necessary to form electrodes facing each other as in the conventional example in order to detect the water level in a water tank or the like, and an electrode having one electrode surface is used. It can be used to detect the water level by the electrical resistance or capacitance with water. And since the electric resistance or the electrostatic capacitance is detected in this way, it is not easily affected even if an insulative material, such as water stains or sticky suspended matter, adheres to the electrode surface, and it becomes possible to reliably detect the water level,
Not only purified water but also sewage can be detected stably.

Further, since the weak leak current flowing through the earth is not utilized, it is not necessary to adjust the sensitivity to the polarity of the commercial AC power source, and the water level of any water tank such as a water tank made of an insulating material such as plastic can be detected. Further, the water level can be detected using a power source other than the commercial AC power source, for example, a generator.

[0029]

EXAMPLES Next, the present invention will be described in detail with reference to examples.

Embodiment 1 FIG. 1 is a circuit diagram showing an example of the overall structure of a water level detecting device of the present invention.

In this embodiment, the water level detecting device of the present invention is applied to a water level control device for keeping the water level in a water tank at a predetermined level. The electrodes (E4), (E5), and (E6) used were those shown in FIG. 2 described above.

The commercial AC power source (21) is connected to the power transformer (22) of the water level detecting device. The power transformer (22) lowers the commercial AC power to a low voltage, for example, 12V, and has a rectifier circuit (23) connected to the secondary side thereof to supply DC power to each part of the water level detection device. It is a thing. Connect the negative electrode side to the ground terminal (E) of the submersible pump (31) at one end of this DC power supply, and ground both to the ground. Therefore, the negative electrode side of the DC power supply and the water in the water tank (30) having the submersible pump (31) have the same potential.

The detection circuit (27) includes an integrated circuit (IC1), a resistor (R
6), (R7) and a capacitor (C6), which oscillate at a high frequency, for example, 1 kHz, an oscillator (24), an integrated circuit (IC2) triggered by the oscillator (24) to generate a pulse, and a resistor (R
8), monostable multivibrator (25) consisting of electrodes (E4) connected via a lead wire, and the width (magnitude) of the pulse
Resistance (R9), capacitor (C7), transistor (T
r7), diode (D), relay (Ry4).

The other detection circuits (28) and (29) are not described in detail, but the electrodes (E
5), (E6) and relays (Ry5), (Ry6) are connected.

Now, the A contacts of the relays (Ry4) and (Ry5) (Ry4-1
a), (Ry5-1a) and control relay (X1) relay coil
Connected in series with the commercial AC power supply (21). The A contact (Ry5-1a) of the relay (Ry5) is the A contact (X1-3a) of the control relay (X1).
Are connected in parallel to form a self-holding circuit. The pair of A contacts (X1-1a), (X1-2a) of the control relay (X1) are connected between the terminals of the power source, and supply power to the submersible pump (31) for drainage. Also, the A contact of the relay (Ry6)
(Ry6-1a) is connected to the buzzer (B1), and the buzzer is energized when the warning water level is reached.

Next, the operation of this embodiment will be described.

The electrode (E4) is placed at a predetermined water level in the water tank (30).
~ (E6) is placed. The electrode (E4) is located at the lowest level of water to be retained, the electrode (E5) is located at the highest level of water to be retained, and the electrode (E6) is located at the alarm level.

The water level in the water tank (30) is the electrode (E4) as shown in the figure.
When it reaches the level of the above, the gap between the electrode (E4) and the negative side of the DC power supply, that is, the negative side of the DC power supply and the water tank as described above.
Since the water in (31) has the same potential, the electric resistance and capacitance between the electrode (E4) and the water in the water tank (31) change, and the integrated circuit (I
C1), resistor (R6), (R7), capacitor (C6)
Integrated circuit (IC2) triggered by (24), resistor (R8), electrode
The output pulse width of the monostable multivibrator (25) consisting of (E4) increases, and the judgment output circuit (resistor (R9), capacitor (C7), transistor (Tr7), diode (D), relay (Ry4) ( The relay of 26) is turned on. Therefore,
The relays (Ry4) to (Ry6) are sequentially turned on when the water level exceeds the levels of the electrodes (E4) to (E6), respectively.

When the water level rises and reaches the electrode (E5),
Since the relays (Ry4) and (Ry5) operate, their A contacts (Ry4-1
a) and (Ry5-1a) turn on, and the control relay (X1) turns on. Therefore, while performing self-holding, the submersible pump (31) operates to drain the water in the water tank (30). Even if the water level drops below the level of the upper electrode (E5), the self-holding circuit keeps the control relay (X1) in the ON state, so the submersible pump
(31) is still in operation.

Now, when the water level further decreases and falls below the level of the electrode (E4), the relay (Ry4) is turned off, the self-holding circuit is stopped, the control relay (X1) is turned off, and the submersible pump ( 31) stops.

When the water level suddenly rises and reaches the electrode (E6), the buzzer (B1) sounds to notify the alarm state.

Although the present embodiment describes a water level control device that controls the water level within a certain range by using a plurality of electrodes, the present invention can be applied to a water level detection device that detects a specific water level. Needless to say.

[0043]

As described in the section of the operation, according to the present invention, in order to detect the water level in a water tank or the like, it is not necessary to form electrodes facing each other as in the conventional example, and one electrode surface is provided. The water level can be detected by the electric resistance or the capacitance with water using the electrode having the. Since the electric resistance or the electrostatic capacitance is detected in this way, even if an insulative material, such as scale or adhesive floating matter, is attached to the electrode surface, it is not easily affected and it is possible to reliably detect the water level.
Not only purified water but also sewage can be detected stably.

Even if the use of the electrode having one electrode surface is the same as that of the conventional water level detecting device 2 described above, it does not utilize the weak leak current flowing through the ground, and therefore is sensitive to the polarity of the commercial AC power source. It is possible to detect the water level of any water tank such as a water tank made of an insulating material such as plastic without requiring adjustment, and further to detect the water level using a power source other than the commercial AC power source, for example, a generator.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of the overall configuration of a water level detection device of the present invention.

FIG. 2 is a cross-sectional view showing an example of an electrode having one electrode surface used in the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional water level detection device 1.

4 is a cross-sectional view showing an example of electrodes used in the water level detection device 1 of FIG.

FIG. 5 is a circuit diagram showing an example of the overall configuration of a conventional water level control device 2.

[Explanation of symbols]

(1) ... power transformer, (2a), (2b) ... winding, (3) ... diode bridge, (4) ... diode bridge, (5), (5a),
(5b) ... electrode, (6) ... water tank, (7) ... relay circuit, (8) ...
Cylindrical case, (Tr1), (Tr2)… Transistor, (C1), (C
2)… Capacitor, (R1)… Resistance, (11)… Pole-top transformer, (1
2) ... outlet, (13) ... plug, (14) ... power transformer,
(15)… rectifier circuit, (16)… water tank, (17), (18), (19)… detection circuit, (20)… submersible pump, (E1), (E2), (E3)… electrode, ( C
3), (C4), (C5) ... Capacitor, (R2), (R3), (R4), (R5)
... resistors, (Tr3), (Tr4), (Tr5), (Tr6) ... transistors,
(X)… Control relay, (X-1a), (X-2a), (X-3a)… A contact of control relay (X), (Ry1), (Ry2), (Ry3)… Relay, (Ry1
-1a), (Ry2-1a), (Ry3-1a) ... A contact of relay, (B) ... Buzzer, (21) ... Commercial AC power supply, (22) ... Power transformer, (23)
… Rectifier circuit, (24)… Oscillator, (25)… Monostable multivibrator, (26)… Judgment output circuit, (27), (28), (29)… Detection circuit, (30)… Water tank, (31 ) ... Submersible pump, (32) ... Cable, (33) ... Case, (34) ... Electrode surface, (35) ... Cap, (3
6) ... Electronic circuit, (37) ... Mold resin, (E) ... Ground terminal, (E4), (E5), (E6) ... Electrodes, (IC1), (IC2) ... Integrated circuit, (R6), ( R7), (R8), (R9) ... resistor, (C6), (C7) ... capacitor, (Tr7) ... transistor, (D) ... diode, (X
1)… Control relay, (X1-1a), (X1-2a), (X1-3a)… A contact of control relay (X1), (Ry4), (Ry5), (Ry6)… Relay, (R
(4-1a), (R5-1a), (Ry6-1a)… A contact of relay, (B1)… Buzzer

Claims (1)

[Claims] 1. A water level detection device for detecting the water level of a water tank or the like, comprising: an electrode having a single electrode surface arranged at a predetermined water level in the water tank, and a water tank at the water level where the electrode is arranged. A water level detecting device for detecting and controlling the water level by sensing the electric resistance or the electrostatic capacitance between the electrode and the water when the water surface reaches.