JPH01178825A - Water level detector - Google Patents

Abstract

PURPOSE:To prevent the lowering of water level detection accuracy even when parts are replaced and to facilitate replacement at the time of trouble, by unifying a coil unit containing a diaphragm with a circuit unit. CONSTITUTION:A coil unit 1 is mounted to the mount hole 27 of the potting case 24 of a circuit unit 2 through a rivet. When parts are replaced, condensers 21a, 21b and a coil 10 are adjusted in order to replace the coil unit 1 and the circuit unit 2 and predetermined oscillation frequency is obtained at a predetermined water level. The coil unit 1 is mounted to the circuit unit 2 in an inclined state and a drain hole 4 is provided to the coil unit 1 in the inclined direction of the coil unit 1. Further, a printed circuit board 25 is mounted in the potting case 24 and embedded by moistureproof resin such as an urethane resin.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to water level sensing devices, and more particularly to water level sensing devices for washing machines and the like.

2. Description of the Related Art The structure of a conventional water level detection device is shown in FIGS. 3 and 4. First, in FIG. 3, a magnetic body 11 such as a ferrite core is placed at the lower center of the coil 10, and the magnetic body 11 such as the ferrite core is attached on a diaphragm.

This diaphragm 12 moves up and down due to water pressure, and the magnetic body 11, such as a ferrite core, also moves up and down, and the inductance of the coil 10 changes. The spring 13 makes the change in position of the diaphragm 12 linear with respect to pressure.

FIG. 4 shows the circuit configuration for detecting the change in inductance of the carp) vlo. That is, a CMO that forms an oscillation circuit inside the control circuit 3 consisting of a microcomputer.
S inverter circuit 20. Capacitors 21a and 21b and a self-bias resistor 22 are provided, and a coil/I/1o and a ferrite core 11 are provided externally on the circuit. With this configuration, the water level is detected by reading the inductance change of the coil 10 as a frequency change.

Problems to be Solved by the Invention However, in the conventional water level detection device, the coil/l/10 forming the oscillation circuit and the capacitors 21a and 21b are completely separated. When converting, capacitor 21a.

21b had to be replaced, and variations occurred in the frequency determined by the coil 1o and the capacitors 21a and 21b, making it impossible to detect the water level with high accuracy.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to always detect the water level with high accuracy even when parts are replaced.

Additionally, the purpose is to take moisture-proof measures and improve the reliability of the detection device even when using water.

Means for Solving the Problems In order to achieve the above object, the present invention provides a coil unit consisting of a diaphragm that moves by water pressure, a magnetic body mounted on the diaphragm, and a coil provided near the magnetic body.・Equipped with a circuit unit consisting of a J and an oscillation circuit using the above-mentioned coil as a resonant coil, the above-mentioned circuit unit and coil unit are integrated, and the above-mentioned circuit unit is embedded in a potting case with moisture-proof resin. It is. Additionally, the potting case is installed with its bottom facing upward to prevent water from accumulating inside the case.

Function According to the above configuration, since the circuit unit and coil unit constituting the oscillation circuit are integrated, the frequency for water level detection is adjusted even when parts are replaced, and a predetermined frequency is always output at a predetermined water level. Therefore, it is possible to prevent detection accuracy from decreasing due to replacement. Furthermore, since the circuit unit is coated inside the potting case, reliability can be improved.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a water level detection device in which a coil unit 1 and a circuit unit 2 are integrated. The structure of the coil unit 1 is similar to that shown in FIG.

As shown in FIG. 2, the circuit unit 2 is an integrated circuit, mounted on a printed circuit board 25, and installed inside a potting case 24. 26 is a connector connected to a control circuit 3 of a washing machine or the like. In addition, the circuit unit 2 includes a CMOS inverter 20a1 and a capacitor 21.
a, 21b, and the resonant coil 10 constitute an oscillation circuit, which transmits a pulse signal to the control circuit 3 via the inverter 20b.

The oscillation frequency is determined by the capacitors 21a, 21b and the resonant coil 1.
When the diaphragm moves up and down and the ferrite core 11 moves, the oscillation frequency changes, and the control circuit 3 detects the change in the oscillation frequency and detects the water level change.

The coil unit 1 is attached to the circuit unit 2, and the potting case 24 of the circuit unit 2 is attached through the hole 27.
It is installed via screws. When replacing parts, the capacitor 21a is used to replace the coil unit/nod 1 and the circuit unit 2.

21b and Koi/L/10 are adjusted to obtain a predetermined oscillation frequency at a predetermined water level. The coil unit 1 is attached to the circuit unit 2 in an inclined manner, and a drain hole 4 is provided in the direction in which the coil unit 1 is inclined. A printed circuit board 25 is mounted inside the potting case 24 and is embedded in a moisture-proof resin such as urethane resin, so problems such as corrosion will not occur even when used in a high temperature and high humidity environment such as a bathroom. . Further, since the bottom surface of the potting case 24 is placed upward, water does not accumulate in the potting case 24.

Effects of the Invention As is clear from the above embodiments, according to the present invention, the coil unit and circuit unit, including the diaphragm, are integrated, so even when parts are replaced, the water level detection accuracy is not reduced. In addition, it is easy to replace in case of failure. In addition, the circuit uni-node is embedded in a potting case with moisture-proof resin, so it can be used even in high-temperature, high-humidity environments, improving reliability. Additionally, since the bottom of the potting case is facing up, there is no chance of water accumulating, which eliminates the problem of deterioration due to humidity.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of a water level detection device according to an embodiment of the present invention, Fig. 2 is a circuit diagram of the same water level detection device, Fig. 3 is a sectional view showing the configuration of a conventional water level detection device, and Fig. 4 is a FIG. 3 is a circuit diagram showing the same circuit configuration. DESCRIPTION OF SYMBOLS 1... Coil unit, 2... Circuit unit, 3... Control circuit, 1o... Coil, 11... Magnetic body, 12 ...Diaphragm, 24 ...Potting case, 26
······Printed board. Name of agent: Patent attorney Toshio Nakao and 1 other person4
-11 Go Sotykoku"Case 5---Fillit base ↓Mi No. 2 Figure 10---Korishi

Claims (2)

[Claims] (1) A circuit unit consisting of a diaphragm moved by water pressure, a magnetic body mounted on the diaphragm, a coil provided near the magnetic body, and an oscillation circuit using the coil as a resonant coil. A water level detection device comprising: the circuit unit and the coil unit are integrated, and the circuit unit is embedded in a potting case with a moisture-proof resin. (2) The water level detection device according to claim 1, which is attached so that the bottom of the potting case faces upward to prevent water from accumulating in the potting case.