JPH064657U - Moisture detector - Google Patents

Abstract

(57) [Summary] [Purpose] To shorten the lead wire between the moisture detection sensor and the moisture detection circuit. [Structure] A ring-shaped first member having different diameters in the electrode casing 1.
The electrodes 2 and 3 and the second electrodes 4 and 5 are provided concentrically alternately, the first electrodes are electrically connected to each other, and the second electrodes are electrically connected to each other, and the insulating material 6 is provided between the electrodes 2, 3, 4, and 5. The moisture detection circuit 8 is built in the box 1 of the moisture detection sensor 7 insulated from above. [Effect] Stable detection with high reproducibility is possible without influence of induced noise. Since the control conditions to be set are stable, the accuracy of on-site adjustment of the snow melting system is improved. There is also an energy saving effect because the snow melting system is controlled accurately and the system is properly energized. A commercial power supply can be used as a detection power supply, and electrolytic corrosion can be prevented.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The moisture detecting device of the present invention is used for a snow melting system buried in a road surface such as a road or an airport. Specifically, the snow melting system detects snow accumulated on the road surface, presence of water, etc. It is for doing.

[0002]

[Prior art]

 In recent years, snow melting systems have been introduced in some roads and airports. This snow melting system detects outside air temperature, road surface temperature, the presence or absence of snow on the road surface, and based on the detection results, it is determined whether or not to energize the heater to prevent snow melting and freeze.

A water content detection sensor as shown in FIGS. 3 and 4 is used for these detections. These are two ring-shaped first electrodes 2, 3 and two second electrodes 4, 5 having different diameters inside the electrode box 1 having a ring-shaped bottom (the second electrode 5 is the electrode box 1). And (the upper part of) are concentrically provided alternately, the first electrodes 2 and 3 are electrically connected, and the second electrodes 4 and 5 are electrically connected, and the insulating material 6 is provided between the electrodes 2, 3, 4, and 5. It is insulated with. This moisture detection sensor 7 is installed on the road surface, and as shown in FIG. 4, the lead wire 11 drawn from the first electrode 3 and the second electrode 4 forms the bridge of FIG. It is connected to the moisture detection circuit 8 that operates.

In the moisture detection sensor 7 described above, when snow or water enters between the first and second electrodes and the surface of the insulating material 5 between the electrodes gets wet, the impedance between the adjacent electrodes decreases. . The output from the moisture detection sensor 7 is compared with a preset sensitivity setting input in the moisture detection circuit 8 to determine the presence or absence of moisture, and the determination result is output. In this case, the detection power supply 14 needs an alternating current to prevent electrolytic corrosion, but in order to eliminate an error caused by induction from the power source (commercial power supply) of the snow melting heater (not shown) and the built-in heater 12 shown in FIG. low frequency voltage 10～30H _z are used. The built-in heater 12 is for melting snow or ice on the insulating material 6 and converting it into water. When water becomes water, the impedance between the electrodes is lowered, and detection is possible. Reference numeral 13 in FIG. 4 is a power supply code for supplying power to the built-in heater 12.

[0005]

[Problems to be solved by the device]

1. With the conventional moisture detection sensor 7, it was difficult to perform energy-saving operation under strict conditions because of the following factors. ． If the lead wire 11 becomes long, it is likely to be induced by a large current circuit nearby. ． As shown in FIG. 6, the capacitance C between the two lead wires 11 increases, and the capacitance C enters in parallel between the first and second electrodes 2, 3, 4, and 5, so that the AC impedance decreases. , The detection sensitivity of the water resistance RW is reduced, and the dead zone width between the detection and non-detection increases. ． Since the set point of the control device changes depending on the length of the lead wire 11, the control condition for each control device is not constant. 2. Since the low-frequency voltage 10～30H _z is used as the detection source, it requires special low-frequency oscillator for oscillating the voltage, complex, and expensive.

An object of the present invention is to provide a moisture detecting device capable of shortening the lead wire connecting the moisture detecting sensor and the moisture detecting circuit.

[0007]

[Means for Solving the Problems]

 As shown in FIG. 1, the moisture detector of the present invention has two ring-shaped first electrodes 2 and 3 and two second electrodes 4 and 5 which are different in diameter and are concentrically arranged in an electrode box 1 alternately. The moisture detection sensor 7 is provided in the first electrode 2 and 3 and the second electrodes 4 and 5 are electrically connected to each other, and the electrodes 2, 3, 4 and 5 are insulated by the insulating material 6. In the electrode box 1, the moisture detection circuit 8 for detecting moisture based on the output from the moisture detection sensor 7 is incorporated.

[0008]

[Action]

 In the moisture detecting apparatus of the present invention, the output from the moisture detecting sensor 7 is compared with the preset sensitivity setting input in the moisture detecting circuit 8 to output the determination result. In this case, since the moisture detection circuit 8 is built in the electrode case 1 of the moisture detection sensor 7, the length of the lead wire 11 between the moisture detection sensor 7 and the moisture detection circuit 8 becomes short, and The parallel impedance becomes extremely large, and the capacitance C between the lead wires 11 becomes small. Further, if the lead wire 11 is short, it will be less susceptible to the influence of induction from the large current circuit.

[0009]

【Example】

 The moisture detecting device of the present invention will be described in detail with reference to the embodiments shown in FIGS. In these figures, 7 is a moisture detection sensor, which is a concentric ring-shaped first electrode 2, 3 and ring-shaped second electrode 4, 5 in an electrode box 1 having a ring-shaped bottom. And the insulating material 6 such as an epoxy resin is filled between the adjacent electrodes 2, 3, 4, and 5. The electrodes 2, 3, 4 and 5 are insulated from each other, and the first electrodes 2 and 3 and the second electrodes 4 and 5 are electrically connected.

Reference numeral 8 in FIGS. 1 and 2 denotes a moisture detection circuit that detects moisture based on the output from the moisture detection sensor 7, and is incorporated in the electrode box 1 of the moisture detection sensor 7. In this case, the electronic circuit portion of the moisture detection circuit 8 is made waterproof by being housed in a waterproof box or filled with a preventive material.

For the output circuit of the moisture detection circuit 8, a relay contact or an open collector output circuit by a transistor Tr as shown in FIG. 2 is used, and its output is a binary signal of ON-OFF ( It is desirable to indicate the presence or absence of water). Since the binary signal is very strong against external induction, stable signal transmission is possible. The sensitivity of the moisture detection circuit 8 is set by a variable resistor inserted in the DC circuit. As a result, the output side and the input side are DC circuits, so it is possible to insert a bypass capacitor sufficiently and stabilize the AC induction.

Reference numeral 12 in FIGS. 1 and 2 denotes a built-in heater built in the box 1. In the present invention, the power source for the built-in heater 12 is shared with the power source for the moisture detecting circuit 8. The power supply for the heater varies from 8V to 15V, so the usable voltage range of the shared circuit is designed to be wide.

2 and 3, 11 is a lead wire for transmitting the detection signals from the first electrode 3 and the second electrode 4 to the moisture detection circuit 8, and 13 is a power supply cord for supplying power to the built-in heater 12. Is.

[0014]

[Effect of device]

The moisture detecting device of the present invention has the following effects. ． Since the moisture detection sensor 7 and the moisture detection circuit 8 are close to each other, the influence of inductive noise is eliminated, and stable detection with high reproducibility becomes possible. ． Since the set control conditions are not affected by the wiring conditions and are stable, the accuracy of on-site adjustment of the snow melting system is improved. ． Since the snow melting system is accurately controlled and the snow melting system is properly energized, it is expected that energy saving will be achieved. ． Since the lead wire 11 is short, it is unlikely to be affected by induction from the large current circuit. Therefore Ki is permitted to use the commercial power supply 50 or 60H _z as a detection power source 14, it is possible to prevent electrolytic corrosion.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a moisture detector of the present invention.

FIG. 2 is a wiring diagram of the moisture detector of the present invention.

FIG. 3 is a plan view of a conventional moisture detector.

FIG. 4 is a vertical cross-sectional view of a conventional moisture detector.

FIG. 5 is a connection diagram of a conventional moisture detector.

FIG. 6 is an equivalent circuit diagram of a conventional moisture detector.

[Explanation of symbols]

 1 Electrode Box 2, 3 First Electrode 4, 5 Second Electrode 6 Insulation Material 7 Moisture Detection Sensor 8 Moisture Detection Circuit

Claims (1)

[Scope of utility model registration request] 1. An electrode box 1 is provided with two ring-shaped first electrodes 2 and 3 and two second electrodes 4 and 5 having different diameters, which are arranged concentrically and alternately. 3 and the second electrodes 4 and 5 are electrically connected to each other, and the electrodes 2, 3, 4, and 5 are electrically connected.
A moisture detecting circuit 8 for detecting moisture based on an output from the moisture detecting sensor 7 is incorporated in the electrode box 1 of the moisture detecting sensor 7 having a space insulated by an insulating material 6. Moisture detector.