JPS6392391A - Water level detector of washing machine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a water level detection device for a washing machine.

Prior Art As a new method for water level detection in washing machines, the inventors have proposed a method that takes advantage of the fact that induction from the commercial power source occurs via straight capacitance when electrodes come into contact with water in the washing tub. . That is, as shown in FIG. 4, an electrode 8 is held at an appropriate position to detect the water level of the washing tub 1 and whose surface is covered with an electrically insulating layer having an appropriate thickness, and an electrode 8 3''-' A shielded wire 1o that is composed of a core wire 11 and a shield member 12, one end of the core wire 11 is connected to the electrode 8, and is electrostatically shielded by applying an appropriate potential to the shield member 12; The core wire 1 of the shield wire 10
A load resistor 15 inserted via a capacitor 14 between the other end of the load resistor 15 and a reference potential section 13 having an appropriate reference potential, and an induced electromotive force detection section that detects the induced electromotive force generated in this load resistor 16. 16, and a determining unit 17 that receives the output of the induced electromotive force detection unit 16 and determines that the water level has reached the electrode portion when the induced electromotive force generated in the load resistor 16 is equal to or higher than a predetermined level. This is a water level detection device for washing machines, etc.

The potential of the reference potential section 13 is made to match the potential of one power supply line of the commercial power supply 6. In addition, 7 is the judgment unit 17
This is a control unit that controls the driving means 3 that drives the pulsator 2 at the inner bottom of the washing tub 1 based on signals from the washing tub 1.

The operation of the water level detection device for a washing machine or the like configured as described above will be explained. That is, when the water level reaches the position of the electrode 8,
Since the water metal body is capacitively coupled to the electrode 8 via the electrical insulating layer, induced electromotive force from the commercial power supply 6 induced from the wiring of the motor etc. is generated in the load resistor 16, thereby detecting the arrival of the water level. ing. Furthermore, by providing an electrically insulating layer on the electrode, safety against electric shock was improved.

Problems to be Solved by the Invention However, in these cases, although the measures are perfect for the electrode 8 and the core wire 10 of the shielded wire 9 that connects it, the measures are insufficient for the shield member 11 of the shielded wire 9. There was a risk of electric shock if the cover was torn and the unit was submerged in water. As a countermeasure to this problem, a method has been proposed in which the shielding member 11 is connected to the circuit through an element with sufficiently high impedance, but with this method, the shielding effect is slightly reduced, the S/N ratio is slightly degraded, and large disturbances occur. However, there are cases where it becomes undetectable.

An object of the present invention is to provide a water level detection device for a washing machine that solves this problem.

Means for Solving the Problem 6''--In order to achieve the above object, the present invention provides an electrically insulating layer which is provided at an appropriate position to detect the water level of the washing tub and whose surface has an appropriate thickness. It consists of an electrode covered by a wire, a covered lead wire to which this electrode is connected, a core wire, and a shield member, one end of the core wire is connected to the wave 431J-cord wire, and an appropriate wire is connected to the shield member. A shielded wire to which electrostatic shielding is applied by applying a potential, a capacitor having one end connected to the other end of the core wire of the shielded wire, and a reference potential portion having an appropriate reference potential with the other end of the capacitor. A load resistor inserted between the two, an induced electromotive force detection section that detects the induced electromotive force generated in the load resistance, and an induced electromotive force generated in the load resistance upon receiving the output of the induced electromotive force detection section. It has a determination unit that determines that the water level has reached the electrode portion when the water level is above a predetermined level, and the covered IJ-do wire is at least easily touched by a user or has a possibility of being submerged in water. This is a water level detection device for a washing machine that is used at certain locations.

Effect When the water level reaches the electrode position with the above configuration, the water metal body is capacitively coupled to the electrode via the electrical insulating layer, so that the induced electromotive force from the commercial power source induced from the wiring of the motor etc. is applied to the load resistance. This occurs, and it is possible to detect when the water level has reached the water level. In addition, by constructing covered lead wires without shielding material in areas that may be easily touched by the user or submerged in water, electric shock can be avoided even if the shielding material of the shielded wire is exposed due to some kind of breakage. It can be prevented.

Embodiment FIG. 1 shows an embodiment of the present invention. Parts that are the same as those shown in Figure 4 are designated by the same numbers. 1 is washing m
2 is a pulsator; 3 is a driving means for driving the pulsator 2; Reference numeral 4 denotes a communication section, which is provided in the side wall of the washing tub 1, through which the water in the washing tub 1 is guided through the slit 5, and is brought to the same water level as the washing tub 1. A commercial power supply 6 serves as a power source for the entire embodiment.

Reference numeral 7 denotes a control unit that controls the entire operation of this embodiment, and is supplied with power from a commercial power source 6 to control the driving means 37'' and notify the user.The control unit 7 shown in FIG.
Power is supplied from the (+) and (-) terminals of the water level detector to be described below. This (+) terminal is still connected to one side of the commercial power supply 6 so as to have the same potential. This is also because the control section 7 uses a triac to control the energization of the driving means 3, so that the circuit voltage of the control section 7 itself must match one side of the power supply line.

Reference numeral 8 denotes an electrode fixed by suitable support means for detecting the water level, and is movable in the vertical direction so that it can be placed at a position desired by the user.

9 is a covered lead wire to which the electrode 8 is connected.

Reference numeral 10 denotes a shielded wire, the core wire 11 of which is connected to the covered lead wire 9. The shield member 12 of the shield wire 10 is connected to a reference potential section 13, that is, the ground of the circuit. A capacitor 14 is connected to the core wire 11 of the shielded wire 10, and a load resistor 15 is connected between the capacitor 14 and the reference potential section 13. Reference numeral 16 denotes an induced electromotive force detection unit that amplifies, rectifies, and smoothes the induced electromotive force generated at both ends of the load resistor 16 from the commercial power source 6 to the electrode 8, and detects its level. Reference numeral 17 denotes a determination unit which receives the output of the induced electromotive force detection unit 16 and determines whether the magnitude of the induced electromotive force is equal to or higher than a predetermined level. The output of the judgment section 17 is sent to the control section 7.
The induced electromotive force detection section 16 and the judgment section 17 are supplied with power from the control section 7 .

The reason why the shield wire 10 is used here is to remove unnecessary induction picked up by the wiring when detecting the induced electromotive force.

FIG. 2 shows the structure of the electrode 8. The figure ( ) is a plan view of the electrode 8 viewed from above, and the figure ( ) is its xx' cross-sectional view. In the figure, 18 is a conductor portion of the electrode 8, to which the core wire 11 of the shield wire 1o is connected. Reference numeral 19 denotes an electrically insulating layer covering the surface of the conductor portion 18 of the electrode 8. This electrical insulating layer 19 is provided so that the conductor portion 1B does not come into direct contact with water. The reason why the electrical insulating layer 19 is provided on the surface of the electrode is that if the conductor part 18 comes into direct contact with water, there is a risk of electric shock if the user comes into contact with water when the capacitor 14 short-circuits due to some kind of failure. This is because of its nature.

When the electrode 8 contacts the water surface, the conductor portion 18 and the water are capacitively coupled by the electrically insulating layer 19 . This capacitance is the conductor part 1
8 diameter 3 (7), thickness of electrical insulating layer 19 0.11M
, the material of the electrical insulating layer 19 is vinyl chloride (relative dielectric constant 4.
5), it becomes approximately 280 pF.

The resulting current is approximately 10μ8 even if 10O2 of the commercial power supply 6 is applied directly between the conductor portion 18 and water, so there is no risk of electric shock.

Next, the operation of water level detection will be explained. Figure 3 shows the principle diagram. A power supply circuit 2o indicates a power supply for the circuit generated in the control unit 7.

6, 14, and 15 are the commercial power sources shown in Figure 1, respectively.

The same number is assigned to the capacitor and load resistor. In FIG. 1, the load resistor 15 is connected to the reference potential section 13, and one power line of the commercial power supply 6 is connected to the positive power supply side of the circuit, so the voltage drop due to the power supply circuit 2o matches the power supply voltage of the circuit. do.

Since this voltage drop is about a few volts, 10 of the commercial power supply 6
It can be almost ignored for 0V. In other words, the potential of the reference potential unit 13 substantially matches the potential of the power supply line on one side of the commercial AC 60. On the other hand, the electrode 8 and the opposite side of the power supply line are coupled by a stray capacitance through the wiring of the driving means 3, as shown in FIG. 21 in FIG. 3 indicates this stray capacitance.

When the electrode 8 is not in contact with the water in the washing tub 1, the stray capacitance 21 is 1 to 21) F, but when it is in contact with water, it reaches around 100 pF.

This is thought to be because the water metal body acts as an electrode of the capacitor.

Now, set the voltage of commercial AC 6 to ■8, load resistance 15 to RL, capacitor 14iC0, and stray capacitance 21 to C.
s, and the capacitance 22 due to the electrical insulating layer 19 is Cc, the induced electromotive force vr generated across the load resistor 15 is expressed as 11 (where ω-2πfCf is the frequency of the commercial power source 6). Vs=100 (Vimg), RL-=10
0(KQ), C0=1000(pF], CC=280(
pF), f = 50 (H2), the amplitude of V when the electrode 8 is not in contact with water (C3 = 1 (1) F) is approximately 4.4 mV, and when it is in contact with water (C5 = 100 ( p
F]) is 305 mV.

The induced electromotive force detection section 16 amplifies, rectifies, and smoothes this induced electromotive force vr, and the judgment section 17 judges whether this is equal to or higher than a predetermined level. In this example, the amplitude of ■1 is 100
When the voltage exceeds mV, it is determined that the water level has reached the electrode 8 portion. In this way, it is possible to detect the arrival of the water level during water supply.

In this embodiment, the capacitor 14 is 1000 pF,
The impedance of the toso is so small that it can be ignored compared to the stray capacitance 21. t7j induced electromotive force detection unit 1
6 is short-circuited due to some kind of failure, and the potential of the power supply line is applied to the one-way capacitor 14.
Even if you directly touch the conductor part 18 of the
Since the current is about 0/jA, there is no need to worry about electric shock. Therefore, by inserting this capacitor 14, all measures against electric shock can be taken regardless of the detection sensitivity.

Further, as described above, the conductor portion 18 is formed by the electrical insulating layer 19vC.
Since it is covered, double safety measures are taken and it is extremely safe.

Furthermore, in areas that are likely to be easily touched by the user or submerged in water, the electrode 8 is connected to the shielded wire 10 by a covered lead wire 9, so the sheathing of the covered lead wire 9 may be torn in this area. Due to the presence of the capacitor 14 mentioned above, there is no risk of electric shock. That is, in the past, this section was entirely composed of shielded wires, so the covering of the shielding member was torn and f? In this case, there was a risk that the potential of the circuit would be directly applied to the human body, but this can be avoided by configuring covered lead wires 9 only for those parts that pose such a risk.

13ゝ-・ Also, since there is no shielding effect in this section, there is a possibility that it will be affected by external disturbances, but since this section is about 20 meters long, it can be considered that there will be no problem of undetectability due to this.

Effects of the Invention As described above, according to the present invention, all risks of electric shock are eliminated by using covered lead wires instead of shielded wires in areas that may be touched by the user or submerged in water. can do.

Furthermore, this does not reduce the shielding effect to the extent that it becomes undetectable, so it is very effective in actual use.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the water level detection device for a washing machine according to the present invention, and Fig. 2 (a) and (b) are a plan view and a side cross section showing the structure of the electrodes of the water level detection device for the washing machine. 3 is a principle diagram of the water level detection device of the same washing machine, and FIG. 4 is a configuration diagram of the water level detection device proposed by the inventor. 8... Electrode, 9... Covered lead wire, 10...
・Shield wire, 11... Core wire, 12... Shield part strength, 13... Reference potential part, 14...
・Capacitor, 15...Load resistance, 16...
- Induced electromotive force detection section, 17... Judgment section, 18.
...Conductor part, 19... Electrical insulating layer. Name of agent: Patent attorney Toshio Nakao and one other person
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Claims (3)

[Claims] (1) An electrode provided at an appropriate position to detect the water level of the washing tub and whose surface is covered with an electrically insulating layer having an appropriate thickness, and a covered lead wire to which this electrode is connected;
A shielded wire is composed of a core wire and a shield member, one end of the core wire is connected to the covered lead wire, and an electrostatic shield is applied by applying an appropriate potential to the shield member; A capacitor whose one end is connected to the other end of the core wire, a load resistor inserted between the other end of this capacitor and a reference potential section having an appropriate reference potential, and an induced electromotive force generated in this load resistor. an induced electromotive force detection unit that detects the induced electromotive force detection unit; and a determination that the water level has reached the electrode portion when the induced electromotive force generated in the load resistor in response to the output of the induced electromotive force detection unit is equal to or higher than a predetermined level; A water level detection device for a washing machine, wherein the coated lead wire is used at least over a portion that is easily touched by a user or is likely to be submerged in water. (2) The water level detection device for a washing machine according to claim 1, wherein the potential of the reference potential section to which the load resistor is connected is made to substantially match the potential of one power line of the commercial power source. (3) The water level detection device for a washing machine according to claim 1, wherein the induced electromotive force detection section amplifies, rectifies, and smoothes the induced electromotive force generated in the load resistance.