JPH067328Y2 - Water level detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a water level detection device used for detecting the water level in an aquarium.

(Prior Art) Conventionally, as a detection device for detecting the water level in a water tank, for example, a device as shown in FIG. 2 has been used. In the figure, the water level detection device has a power transformer 1 for stepping down commercial AC power, and its secondary winding has two windings 2a,
2b is formed. A diode bridge 3 is connected to one end of the secondary winding 2a, and a switching circuit composed of transistors Tr1 and Tr2 is connected to the output side of the secondary winding 2a via a capacitor C1. 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 inserted into the water tank 6 at a predetermined interval. The other end of the diode bridge 4 is connected to the base of the transistor Trl via the resistor C1 as a negative DC voltage via the capacitor C2. The transistors Tr1 and Tr2 are connected so as to be turned on and off alternately, and the relay circuit 7 is connected to the collector of the transistor Tr2. As for the electrode 5, for example, as shown in FIG. 3, a cylindrical case 8 has a cylindrical electrode 5a at its tip, a central electrode 5b is arranged at the center thereof, and an electrode formed by integrally molding these with resin or the like is used. Used.

Now, if the water level in the water tank 6 does not reach the level of the electrodes 5a and 5b, this negative voltage will not be applied to the base of the transistor Tr1.
1 is turned on, the transistor Tr2 is turned off, and the relay circuit 7 connected to its collector does not operate. However, when the water level of the aquarium reaches the level of the electrodes 5a and 5b due to the rise of the water level, a negative voltage is applied to the base of the transistor Tr1 via the diode bridge 4 and the transistor Tr1
Is off, transistor Tr2 is on and relay circuit 7
Is activated, and a pump or the like (not shown) can be activated.

As another detection device for detecting the water level in the water tank, there is also known a device in which a float switch having a mercury switch enclosed therein is used to detect a predetermined level in the water tank. In this system, a mercury switch inside the float switch is made conductive based on a change in the inclination of the float switch that floats on the water surface as the water level rises, thereby detecting a predetermined level of water level.

(Problems to be solved by the invention) However, according to such a conventional water level detection device of FIGS. 2 and 3, two electrodes 5a and 5b are inserted as the electrodes so as to face each other at the same water level. There is a need. And because the resistance value of the water in the aquarium is large, a low voltage (for example, 12
Since it is operated at V or 24V), the distance between the electrodes cannot be increased so much. Therefore, if water stains adhere to the surface of the electrodes or sticky suspended matter adheres between the electrodes, it is operated at a low voltage. Therefore, there is a drawback that the adhesion is large and that the malfunction may occur regardless of whether the water level reaches the electrodes 5a and 5b, that is, regardless of the level of the water level. In this way, 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. Also clean water, salt water, sewage,
There are drawbacks such that the sensitivity is adjusted depending on the quality of water such as medicinal water, and many kinds of electrodes are required.

In addition, when detecting the water level by a float switch using a mercury switch, not only the size of the float switch becomes large, but also the floating float increases in weight due to the adhesion of suspended matter on the float, and the detection level becomes unsatisfactory. There is a risk that it will become clear and malfunction. Further, there is a defect that contact failure due to contact failure of mercury or mercury contamination due to breakage of the float switch is likely to occur.

The present invention has been made in view of the problems of the conventional water level detection device and the electrode thereof, and it is possible to reduce the influence of scale and sticky suspended matter and to accurately detect the water level of any water quality. Making it possible is a technical issue.

(Means for Solving the Problem) The invention according to the present application is a water level detection device for detecting the water level of an aquarium electrically supplied to the ground by a commercial AC power supply whose one end is grounded, , A power supply circuit that rectifies a commercial AC power supply to obtain a predetermined power supply voltage, an electrode that is arranged at a predetermined water level in the water tank and has one electrode surface, and the water surface of the water tank reaches the water level where the electrode is arranged. In this case, a commercial AC leak current leak current obtained from the electrode is amplified, and a detection circuit for detecting and controlling the water level based on the amplified output is provided.

(Operation) According to the invention of the present application having such a feature, the water level detection device is supplied with power from the commercial AC power supply whose one end is grounded. Then, an electrode rod having one electrode surface is arranged at a predetermined level position in a water tank electrically grounded to the ground. When the water level reaches the electrode surface, a leak current is obtained from the commercial AC power source whose one end is grounded to the electrode through the ground and the water tank. The leak current is amplified by an amplifier circuit and its level is detected to detect that the water level has reached the position of the electrode.

(Embodiment) Next, an embodiment of the invention according to the present application will be described with reference to FIG. In this embodiment, the water level detection 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. Now, for the utility pole, for example, 6,000V
A pole transformer 11 that reduces the commercial AC voltage to 100V is provided. One end on the secondary side of the pole transformer 11 facilitates maintenance and inspection of the transmission and distribution lines, and one end is grounded as shown to prevent high voltage from entering the home due to burning of the pole transformer. Has been done. The power transformer 14 of the water level control device is connected from the secondary side of the pole transformer 11 via the outlet 12 and the plug 13.
The power transformer 14 is a commercial AC power source of low voltage, for example, 12V.
Alternatively, the voltage is reduced to 24V, and the rectifier circuit 15 is connected to the secondary side of the voltage to supply a voltage to each part of the water level detection device. Here, the power supply transformer 14 and the rectifier circuit 15 configure a power supply circuit that rectifies a commercial AC power supply to obtain a predetermined power supply voltage.

Now, in the water tank 16, a plurality of electrodes E1 are placed at predetermined water levels.
~ E3 are arranged. The electrode E1 is an electrode arranged at the lowest level of the water level to be held, and the detection circuit 17 is connected to the electrode E1 via a lead wire. The detection circuit 17 has a capacitor C3 and a resistor R2 directly connected to the lead wire, and the other end is connected to the base of the transistor Tr3. Transistors Tr3 and Tr4 are connected in Darlington to increase the amplification factor and input impedance. And the emitter of the transistor Tr4 is grounded,
A 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. The collector is connected to the base of a PNP transistor Tr5 via resistors R4 and R5, and the common connection end of the resistors R4 and R5 and the capacitor C5 are connected to the positive end to form a kind of timer circuit for chattering. To prevent. The transistors Tr5 and Tr6 are Darlington-connected, and the relay R1 is connected between the emitter of the transistor Tr6 and the ground terminal. Similar detection circuits 18 and 19 are connected to the other electrodes E2 and E3. Although detailed description of the configuration of the detection circuits 18 and 19 is omitted,
Relays R2 and R3 are respectively connected.

Now, the A contacts of the relays R1 and R2, R1-1a and R2-1
a and the relay coil of the control relay X are connected in series to the commercial AC power supply. The A contact R2-1a of the relay R2 is connected in parallel with the A contact X-3a of the control relay X to form a self-holding circuit. A pair of A contacts X of the control relay X
-1a and X-2a are respectively connected between the terminals of a power supply, and supply power to the submersible pump 20 for drainage. Further, the A contact R3-1a of the relay R3 is connected to the buzzer B, and energizes the buzzer when the warning water level is reached.

Next, the operation of this embodiment will be described. When the water level in the water tank 16 reaches or exceeds the level of the electrode E1 as shown in the figure, the grounding portion and ground on the secondary side of the pole transformer 11, the water tank 16,
The water in the water tank 16 and the electrode E1, the detection circuit 17 and the stray capacity between the primary and secondary windings of the power transformer 14 and the secondary winding of the pole transformer 11 are AC-coupled in that order. A leak current of a minute level, for example, about several μA flows from the commercial AC power supply. This leak current is amplified by the transistors Tr3 and Tr4 connected in Darlington. 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 Tr4 becomes about 1.5 V or more, the transistors Tr3 and Tr4 operate, and the leakage current is the product of the current amplification factors of these transistors. It is amplified by the amplification factor, and the collector current flows through the transistor Tr4. Therefore, the base current also flows through the transistors Tr5 and Tr6 and the relay R1 is energized. At this time, current flows through the capacitor C5 and the resistor R4,
The capacitor C5 is charged. Even if TR3 and TR4 are turned off due to the water level being lowered by the charging voltage of the capacitor C5, the relay is turned off after a predetermined time delay. Therefore, the relays R1 to R3 are sequentially turned on when the water level exceeds the levels of the electrodes E1 to E3, respectively. Therefore, when the water level rises and reaches the electrode E2, the relays R1 and R2 operate, so that their A contacts R1-1a and R2-1a are turned on and the control relay X is energized. Therefore, while performing self-holding, the submersible pump 20 operates to drain the water in the water tank 16. Even if the water level drops and falls below the level of the upper electrode E2, the self-holding circuit keeps the control relay X in the ON state, so that the submersible pump 20 continues to operate. Now, when the level of the electrode E1 becomes lower than the level, the relay R1 is deenergized, so that the self-holding circuit stops, the control relay X turns off, and the submersible pump stops. Also, the water level suddenly rises and the electrode E
When the water level reaches 3, the buzzer sounds to notify the alarm condition.

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, it goes without saying that the present invention can be applied to a water level detection device that detects a specific water level. Nor.

(Effect of the Invention) As described above, according to the invention of the present application, in order to detect the water level in the water tank, it is not necessary to form electrodes facing each other as in the conventional example, and an electrode having one electrode surface is used. The water level can be detected by the leak current. Since the leak current is utilized in this way, the input impedance and the gain of the detection circuit are high. Therefore, even if water stains adhere to the electrode surface or sticky suspended matter adheres between the electrodes, it is not affected by it and the water level can be detected reliably, and it is necessary to adjust the sensitivity depending on the water quality. Nor.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an overall configuration of a water level control device according to an embodiment of the invention according to the present application, FIG. 2 is a circuit diagram showing an example of a conventional water level detection device, and FIG. 3 is an example of a conventional electrode rod. FIG. 11 ... Pillar transformer, 14 ... Power transformer, 15 ...
… Rectifier circuit, 16 …… Water tank, 17-19 …… Detection circuit,
E1 to E3 ... Electrodes.

Front page continuation (72) Inventor Toshinori Uchiyama 9-10 Shimohirabuki-cho, Takefu-shi, Fukui Prefecture Kuramo Electric Co., Ltd. (72) Inventor Shigehiro Kato 10-9 Shimohirabuki-cho, Takefu-shi, Fukui Kuramo Electric Within the corporation (56) References Japanese Patent Laid-Open No. 56-112613 (JP, A) Actually developed 53-28750 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A water level detector for detecting the water level of a water tank which is supplied with power from a commercial AC power supply whose one end is grounded and which is electrically grounded to the ground. A power supply circuit for obtaining a power supply voltage, an electrode having one electrode surface arranged at a predetermined water level in the water tank, and obtained from the electrode when the water surface of the water tank reaches the water level at which the electrode is arranged. A water level detection device, comprising: a detection circuit that amplifies a commercial AC leak current and detects and controls the water level based on the amplified output.