JPH0241994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a water level detection device for a washing machine having a washing and dehydrating tub.

Conventional structure and its problems Conventionally, in a single-tank dehydrating washing machine, an outer tub is provided outside the washing and dehydrating tub with small holes for dehydrating in the peripheral side wall, and the outer tub is used during washing and rinsing. Since water was stored inside the tank, the water level inside the washing and dehydrating tank was detected by operating a pressure switch based on changes in the air pressure of an air trap installed on the lower side wall of the outer tank. . However, with this structure, water is stored between the outer tank and the washing and dehydrating tank.
The drawback was that it required a large amount of washing water.

In addition, a washing/dehydration tank without a small hole for dewatering in the surrounding wall was proposed, and it was considered to collect water only in this tank for washing, but in this case, if the water level was detected using a pressure switch, In this case, it was necessary to provide an air trap in the rotating shaft portion, which made the waterway complicated and significantly increased the cost required for the drainage system.

Further, a float having a magnet that moves up and down according to the water level in the washing and dehydration tank and a reed switch that is opened and closed by the float are provided, and the reed switch is connected to the washing and dehydration tank and its bearing part. A method of connecting to the control circuit via a sliding contact installed between the two was considered, but durability was poor due to wear of the sliding parts, and stabilization of the waterproof structure was a major problem in practical use. I was getting used to it.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, enables water level detection without using a pressure switch, an air trap device, etc., and improves water level detection accuracy.

Structure of the Invention In order to achieve the above object, the water level detection device for a washing machine of the present invention includes a water level detection unit provided at a predetermined position on the side wall of a washing and dehydration tank whose circumferential wall except for at least the upper end is a non-porous wall. A rotary transformer is installed between the bottom of the washing and dehydrating tank and the outer tank to take out the water level detection signal from this detection part to the outside through inductance coupling. , is wound around an iron core made of a magnetic material provided approximately at the center of the bottom of the outer tank containing the washing and dehydrating tank, and the secondary winding is provided on the bottom outer tank side of the washing and dehydrating tank and electrically connected to the detection unit. It is connected to.

DESCRIPTION OF EMBODIMENTS Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the figure, 1 is an outer frame, 2 is a washing and dehydrating tank with a non-porous peripheral wall except at least the upper end, 3 is an outer tank containing the washing and dehydrating tank 2, and 4 is a washing and dehydrating tank 2
5 is a brake/clutch mechanism, 6 is a motor, 7 is a motor pulley, 8 is a belt, 9 is an impeller pulley, and 10 is a vibration-proof support device hanging from the four corners of the outer frame 1. , supporting the outer tank 3.

11 is a rotary transformer having a movable part;
1a is the primary winding of the transformer 11, and 11b is an iron core made of a magnetic material such as ferrite, around which the primary winding 11a of the transformer 11 is wound. The secondary winding 11c is fixed to the bottom of the washing/drying tub 2, and the iron core 11b is fixed to the outer tub 3.
Reference numeral 12 denotes a lint filtration circulation path provided on a part of the side wall of the washing/dehydration tank 2, and a lint filtration filter 13 is provided at the upper part.

14a, 14b, 14c are electrodes for water level detection provided in the lint filtration circulation path 12;
14a and 14b indicate electrodes for detecting a water level reset, and electrodes 14a and 14b for detecting a water level set, the former 14a being for detecting a high water level and the latter 14b being for detecting a low water level.

Here, to explain in more detail the installation state of the rotary transformer 11, the primary winding 11a is connected to the control circuit as shown in FIG. 3, and the secondary winding 11c is connected to the control circuit.
are connected to the water level setting electrodes 14a, 14b, and 14c via lead wires.

Here, the width B of the iron core 11b is made larger than the winding widths A and A' of the primary and windings 11a and 11c.

FIG. 3 is a block diagram showing the basic configuration of the detection circuit, where 15 is an AC power supply, 16 is a load control unit that controls the opening and closing of the relay 17, and the relay contact 1
7a controls the loads of the washing machine motor, water supply valve, timer motor, etc. 18 is a water level setting section that sets the water level using water level setting changeover switches 19a and 19b; 20 is an oscillation circuit section that obtains an arbitrary oscillation frequency, for example 1 MHz, from the DC power supply section 21;
is a rotary transformer having a movable part as described above, 11a and 11c are the primary and secondary windings of the transformer, 22a, 22b, 22c are the electrodes 14a,
A fixed resistor connected in series with 14b and 14c,
The resistance value of the resistor 22c connected to the reset water level detection electrode 14c is high, and the high water level detection electrode 14a
The resistance value of the resistor 22a connected to is set low.

Next, the operation will be described. When the timer circuit of the washing machine is energized now, the water supply valve operates in the water supply process, and water is supplied into the washing and dehydrating tub 2. At this time, the water level detection device is also energized. At the initial stage of water supply, electrodes 14a, 14b, 14 for water level detection are installed.
Water is not in contact with any of the electrodes, and the resistance value of each electrode is close to infinite. Therefore, in this state, the oscillation circuit section 20 oscillates at the set oscillation frequency and the load control section 16 is not operating, so the relay 17 does not operate and the relay contact 1
7a is closed to the NC side.

When the water level setting section 19 is set to a high water level, that is, when it is connected to the water level setting changeover switch 19a, water supply continues and the water level is set at the electrode 1.
4a, the oscillation circuit section 20 is unable to maintain the set oscillation frequency and oscillation stops or the oscillation voltage drops below the reference value, so the load control section 16 does not operate. The relay 17 is activated, the relay contact 17a is switched to the NO side, the motor 9 is operated, the pulsator 4 is rotated, and washing or rinsing is started. At this time, when the water level falls below the position of the water level setting electrode 14a or 14b due to water level fluctuation, the oscillation circuit section 20 has a configuration that maintains the above state.

When the water level falls below the water level reset detection electrode 14c, the oscillation circuit section 20 oscillates again at the set oscillation frequency, and the load control section 16 becomes inoperable.
Relay 17 is opened and relay contact 17a is opened again.
When it is closed to the NC side, the operation of the motor 6 is stopped and the rotation of the pulsator 4 is stopped.

Here, since the width B of the iron core 11b is made larger than the winding widths A and A' of the primary and secondary windings 11a and 11c, it is possible to suppress the leakage magnetic flux from the primary winding 11a to a minimum value. can.

Effects of the Invention As described above, according to the present invention, by providing the primary winding of the rotary transformer for detecting water level detection signals, that is, the oscillation circuit side, by winding or the like around an iron core made of a magnetic material such as ferrite, It is possible to reduce leakage magnetic flux from the primary winding to the secondary winding, increase the degree of magnetic coupling, ensure the transmission of water level detection signals, and perform accurate water level control. By providing an iron core made of magnetic material on the winding side, it is possible to ignore the magnetic influence of the washing/drying shaft, and it is also possible to eliminate causes of malfunction due to washing water entering the rotary transformer. be effective.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of a washing machine according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the main part showing the installation state of the rotary transformer, and Fig. 3 is a block diagram showing the basic configuration of the water level control device. It is a diagram. 2... Washing and dehydration tank, 3... Outer tank, 11... Rotating transformer, 11a... Primary winding, 11b... Iron core, 11c
...Secondary winding, 14a, 14b, 14c...electrode (detection section).

Claims (1)

[Claims] 1. A water level detection section is provided at a predetermined position on the side wall of a washing/dehydration tank whose circumferential wall, excluding at least the upper end, is a non-porous wall, and a water level detection signal from this detection section is transmitted externally by inductance coupling. A rotary transformer is installed between the bottom of the washing and dehydrating tank and the outer tank, and the primary winding of this rotary transformer, which is connected to the oscillation circuit, is connected to the bottom of the outer tank that contains the washing and dehydrating tank. Wrapped around an iron core made of magnetic material located in the center,
A water level detection device for a washing machine, in which a secondary winding is provided on the bottom outer tank side of a washing and dehydrating tub and is electrically connected to the detection section. 2. The water level detection device for a washing machine according to claim 1, wherein the width of the iron core around which the primary winding is wound is larger than the winding widths of the primary winding and the secondary winding.