JPH03267732A - Water leak detector with electrolytic corrosion preventing circuit - Google Patents

Abstract

PURPOSE:To preclude the electrolytic corrosion of electrodes by providing a switching element between detection sensor electrodes, and turning it on at the stop of a DC pulse for detection and short-circuiting the sensor electrodes forcibly. CONSTITUTION:A water leak detection line sensor 1 is connected to a water leak detecting circuit 2 and one output of a pulse generating circuit 3' is connected to the electrode (a) of the sensor 1 through an inverter 4 while the other is connected to the base of a transistor(TR) 5 through a resistance. The DC pulse generated by the circuit 3' is applied between the electrodes (a) and (b) of the sensor 1 and the other is applied to the base of the TR 5, which is switched to short-circuit the electrodes of the sensor 1 forcibly when the pulse for detection is OFF. Consequently, the electrolytic corrosion of the electrodes of the sensor 1 can be precluded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a DC pulse detection type water leakage detector, in which a charging voltage due to a storage capacitance between detection sensor electrodes generated by a DC pulse for detection is used for detection. By switching in synchronization with the DC pulse, the sensor electrodes are forcibly short-circuited and discharged when the output pulse is stopped.

[Prior art j] In a water leakage detector using an inter-electrode water resistance detection method, DC voltage, AC F & voltage, or M current pulse voltage has conventionally been used as the detection voltage supplied between the electrodes of the detection sensor. When considering future technologies such as power saving, IC, hybridization, application to multi-point detection methods, and application to microcomputer-controlled systems, the DC pulse voltage method is the most effective.

FIG. 3 shows a conventional DC pulse detection type water leak detector.

Connect a water leakage detection line sensor (for example, Tsunaisha S-1F type water leakage detection line sensor) 1 to a water leakage detection circuit 2,
The detection DC pulse shown in Figure 4 is supplied from the pulse generation circuit 3 to the sensor electrode gap a-b, and the detection circuit 2 detects a voltage change due to a change in water resistance between the electrodes that occurs when the sensor electrode gap a-b is submerged in water. Detecting water leaks.

[Problem to be solved by the invention] When a DC pulse voltage is actually used as a detection voltage,
When there is no water between the sensor electrodes (dry), the sensor length -
The electrodes are insulated and the output DC pulse voltage (@4
Figure axis) (9■ to 18■) occurs. However, if the area between the sensor electrodes is submerged in water or in a highly humid state,
The charging voltage (0.9 V ~ 2.5
V) occurs (see Figure 4, see Figure 5), and as a result, the sensor electrode (stainless steel 5us-304) becomes heavy.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention uses switching synchronized with the detection DC pulse to forcibly short-circuit the detection sensor electrodes when the detection DC pulse is paused to charge the sensor. Discharge the voltage to prevent the sensor electrode from being damaged.

As the switching element, a transistor circuit, a photocoupler, a relay, and other various switching elements can be used.

Switching methods include short-circuiting the detection sensor electrodes using a common emitter transistor circuit (oven collector) using a reverse phase pulse synchronized with the DC pulse for detection, and a method using a photocoupler or relay using a reverse phase pulse. A possible method is to short-circuit between the detection sensor electrodes by switching to discharge the charging voltage. Further, instead of the reverse phase pulse for switching, a pulse obtained by delaying the DC pulse for detection by the pulse width may be used.

[Example 1] Figure 1 shows how to prevent electrolytic corrosion of a common emitter transistor circuit @
This is the case when it is set as a road.

A water leakage detection line sensor (for example, Sakesha S1F type water leakage detection line sensor) 1 is connected to the water leakage detection circuit 2, and the output of the pulse generation circuit 3' is connected to the water leakage detection line sensor 1 through the inverter (logical negation circuit) 4 on the negative side. The other end is connected to the electrode a of the line sensor 1, and the other end is connected to the base of the transistor 5 via a resistor.

The transistor 5 has a J-mitter grounded, a base grounded through a resistor, and a collector connected to the electrode a side of the water leak detection line sensor 1 through a resistor.

The DC pulse of the voltage waveform diagram ψ in FIG.
1/10) between the electrodes a of water leakage detection line sensor 1
-b and the other is applied to the base of the transistor 5 to switch the transistor 5 and forcibly short-circuit the detection sensor electrodes when the detection DC pulse (fourth diagram) is OFF.

FIG. 4 is a voltage waveform diagram at the main gIl location in FIGS. 7 to 3. ω is the output voltage waveform of the pulse generation circuit 3', and phantom is a detection DC pulse, which corresponds to the output voltage waveform of the pulse generation circuit 3 or the output voltage waveform of the inverter 4. Q9 is the voltage waveform between the line sensor electrodes when the line sensor 301 is submerged in water to enter the water leak detection state in the conventional example shown in FIG. ) are shown in Figures 1 and 2.
In the embodiment of the present invention with the electrolytic corrosion prevention circuit shown in the figure, the water leakage detection line sensor is submerged in 3001 water! This is the low waveform of the voltage between the electrodes of the line sensor TFI when the water leakage is detected.

FIG. 5 is a partially enlarged view of FIG. 439.

FIG. 6 is a partially enlarged view of FIG. 4.

[Example 2] FIG. 2 shows a case where a photocoupler is used as an electrolytic corrosion prevention circuit.

A water leakage detection line sensor (for example, a 5-1F water leakage detection line sensor) 1 is connected to the water leakage detection circuit 2, and the output of the pulse generation circuit 3' is connected to the water leakage detection line sensor through the inverter 4 on the negative side. 1 and the other electrode is connected to the light emitting diode of the photocoupler 6 via a resistor. The photocoupler 6 grounds the other end of the light emitting diode, and connects the light-receiving side terminals of the photocoupler 6 to the electrode a side and the electrode I side of the water leakage detection line sensor 1, respectively.

The DC pulse of the voltage waveform diagram shown in FIG.
DC pulse for detection (DC12V, Dut
y 1/20) to water leak detection line sensor 1 electric 44i
111a-b, and the other is applied to the photocoupler 6.
The photocoupler 6 is switched by applying the voltage to the light emitting diode to forcibly short-circuit the detection sensor electrodes when the detection DC pulse (FIG. 4 1) is OFF.

[Effects of the Invention] In the case of the conventional detector, when the detection DC pulse is OFF, the charging voltage (0.9V to 2.5V) due to the storage capacitance between the detection line sensor electrodes is applied between the sensor electrodes as shown in FIG. This occurs as shown in Figure 5.

In the case of the detector according to the present invention, the detection DC pulse OF
In order to forcibly short-circuit the charging voltage between the detection sensor electrodes by switching a transistor or a photocoupler at the time of F, the sensor 'l! The pole rM voltage is the fourth
It becomes almost zero as shown in FIG. 0 or FIG.

In addition, in [Embodiment 2], the DC pulse of the voltage waveform diagram of FIG. 4- generated in the pulse generating circuit 3' is
V, Duty is 1/20, a voltage waveform like No. 7N is generated between the sensor electrodes of the conventional detector, and a voltage waveform as shown in FIG. 8 is generated between the sensor electrodes of the detector according to the present invention. A voltage waveform is generated.

Therefore, it is important to prevent electrolytic corrosion of the detection sensor electrode.
Wear.

Note that by using the electrolytic corrosion prevention circuit, it is possible to use materials that are easily subject to electrolytic corrosion (for example, copper, iron, etc.). In addition, because the degree of freedom in electrode structure increases, for example, it becomes possible to use thin electrodes, thin and small electrodes, and electrodes with a narrow inter-electrode distance.
Another effect is that a compact sensor can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention in which a common emitter transistor circuit is used as an electrolytic corrosion prevention circuit. FIG. 2 is a diagram showing another embodiment of the present invention in which a photocoupler is used as an electrolytic corrosion prevention circuit. FIG. 3 is a diagram showing a conventional DC pulse detection type water leak detector. FIG. 4 is a voltage waveform diagram C of the main points in FIGS. 1 to 3. FIG. 5 is a partially enlarged view of FIG. Fig. 6 is a partially enlarged view of Fig. 4 (→). Fig. 7 is a partially enlarged view of Fig. 4 (→) when the voltage waveform of the DC pulse is changed in the second embodiment. Fig. 8 is a partially enlarged view of Fig. 4 (→) when the voltage waveform of the DC pulse is changed in the second embodiment. [Explanation of symbols] 1... Water leak detection Line sensor 2...Water leakage detection circuit 3.3'...Pulse generation circuit 4...Inverter 5...Transistor 6...Photocoupler Fig. 5 Fig. 6

Claims (1)

[Claims] (1) In a DC pulse detection type water leakage detector that supplies a DC pulse for detection between detection sensor electrodes, a switching element is provided between the detection sensor electrodes, and the switching element is turned on when the DC pulse for detection is stopped. A water leakage detector having an electrolytic corrosion prevention circuit that forcibly shorts between the detection sensor electrodes.