JPH0311799B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a water level detection device for a washing machine with a washing and spin-drying function, which has a washing and spin-drying tub whose circumferential wall except at least the upper end is a non-porous wall.

Conventional structure and its problems Conventionally, generally known dehydrating and dehydrating washing machines have an outer tub installed outside the washing and dehydrating tank, which has small holes for dewatering on the circumferential side, and is used for washing and rinsing. Water is also stored inside the outer tank, and the water level is detected by operating a pressure switch in response to changes in air pressure in an air trap provided on the lower side wall of the outer tank. However, this structure has the disadvantage that a large amount of washing water is required because water is stored between the outer tub and the washing/drying tub.

Another idea was to install a washing and dehydration tank without a small hole for dehydration, and store water only in this tank for washing, but in this case, the water level detection method was to use a conventional pressure switch. When detecting water level, it is necessary to install an air trap on the rotating shaft, which complicates the waterway.Furthermore, a drain valve and pressure switch are required, making assembly difficult and making it difficult to achieve accuracy. , and was expensive.

Therefore, we installed a float with a magnet that moves up and down according to the water level in the washing/dehydration tank, and a reed switch that is opened and closed by the magnet of this float.The reed switch is installed between the washing/dehydration tank and the bearing. One possible method is to connect to the control circuit through a sliding contactor, but the durability due to wear of the sliding part, etc.
Also, it was difficult to obtain a waterproof structure, which was a big problem in practical use.

OBJECTS OF THE INVENTION The present invention aims to solve the above-mentioned conventional problems and provide a water level detection device that does not cause wear of the sliding portion and has a waterproof structure.

Structure of the Invention In order to achieve the above-mentioned object, the water level detection device for a washing machine with dehydration and dehydration according to the present invention includes a washing and dehydration tank whose circumferential wall except at least the upper end is a non-porous wall, and a washing and dehydration tank which is rotatably housed. An outer tank, a detection unit for detecting water level disposed at a predetermined position of the washing and dewatering tank, and a water level detection signal from this detection unit is taken out to the outside by magnetic coupling between a primary winding and a secondary winding. The outer tank is made of a resin material, and at the center of the bottom of the outer tank, a recess with an opening inward of the outer tank is provided integrally with the outer tank. Fixing the next winding to the washing and dehydrating tank,
A primary winding wound around an oscillation circuit is accommodated in the recess, and side walls of the primary and secondary windings on the gap side are formed thinner than the other side walls. be.

Description of examples An embodiment of the present invention will be described below.

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 that houses the washing and dehydrating tank 2, and 4 is a washing and dehydrating tank 2
pulsator placed in the center of the inner bottom, 5 is the brake
Clutch mechanism, 6 a motor, 7 a motor pulley,
8 is the belt, 9 is the impeller pulley, 10 is the outer frame 1
Vibration-proof support devices hanging from the four corners support the vibration systems such as the outer tank 3 and the motor 6. 11 is a rotary transformer having a movable part, 11a is a primary winding of this rotary transformer 11, and 11b is a secondary winding of the transformer 11. and secondary winding 11b
is fixed to the outer bottom of the washing and dewatering tub 2, and the primary winding 11a is fixed to the inner bottom of 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, 14
b, 14c are electrodes for water level detection provided in the lint filtration circulation path 12, electrode 14c is for water level reset detection, electrodes 14a and 14b are for water level set detection, and electrode 14a is for high water level,
Electrode 14b detects low water levels.

2 and 3 show the installed state of the rotary transformer 11, in which the primary winding 11a is wound around the winding frame 11c and connected to a control circuit. The secondary winding 11b has water level detection electrodes 14a, 14b, 14
It is connected to c via a lead wire. 1
The next winding 11a is inserted and fixed together with the winding frame 11c into an annular recess 3a provided at the center of the inner bottom of the outer tank 3, and is coated with an insulating resin material.

More specifically, an annular protrusion 3b is integrally formed on the inner bottom of the outer tank 3 made of a resin material, and the above-mentioned annular recess 3a is formed by opening the upper part of the protrusion 3b. There is. In FIG. 2, a protrusion 3 corresponding to the inner diameter side of the recess 3a is shown.
The thickness t of the side wall 3b of c is configured to be thinner than the thickness T of the side wall corresponding to the outer diameter side, thereby,
The gap distance between the primary winding 11a and the secondary winding 11b is set as small as possible.

3 is opposite to FIG. 2 in that the secondary winding 11b is located inside the primary winding 11a, but in this case, the side wall corresponding to the inner diameter side of the recess 3a The thickness t is thinner than the thickness T of the side wall corresponding to the outer diameter side.

In short, the gap distance between the primary and secondary windings 11a and 11b is set small, and the second
The configurations shown in FIG. 3 and FIG. 3 are common.

Fig. 4 is a block diagram showing the basic configuration of the water level detection circuit. 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 17a of the relay 17 controls the washing machine motor. ，
Controls loads such as water supply valves and timer motors. 18
20 is an oscillation circuit section which obtains an arbitrary oscillation frequency, for example 1 MHz, from the DC power supply section 21. 22a, 22b, 22c are electrodes 14a,
Resistor 2 is a fixed resistor connected in series with 14b and 14c, and is connected to the water level reset detection electrode 14c.
The resistance value of the resistor 2c is set high, and the resistance value of the resistor 22a connected to the electrode 14a for high water level detection 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 circuit 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 N and C sides.

When the water level setting unit 18 is set to a high water level, that is, when the water level changeover switch 19a is turned on, water supply continues and when the water level reaches the upper part of the electrode 14a, a short circuit occurs between each electrode. Secondary winding 1
The inductance on the 1b side changes. As a result, the inductance on the primary winding 11a side changes at the same time, so the oscillation circuit section 20 is unable to maintain the set oscillation frequency, and oscillation may stop or
Or, since the oscillation voltage drops below the reference value, the load control unit 16 operates, the relay 17 operates, and the relay contact 17a switches to the N and O sides, and the motor 6
is operated, the pulsator 4 rotates, and washing or rinsing is started.

Here, the primary and secondary windings 1 of the rotating transformer 11
The shorter the gap distance between 1a and 11b, the better the magnetic coupling state of the transformer 11 becomes, and it becomes possible to increase the change in inductance. Therefore, it is preferable to make the side wall of the protrusion 3c of the outer tank 3 as thin as possible, but on the other hand, it is necessary to have sufficient mechanical strength in consideration of vibrations during dewatering.

According to the above configuration, since the thickness t of the side wall 3c of the recess 3a corresponding to the secondary winding 11b is made thinner than the thickness T of the side wall 3b having no corresponding relationship, sufficient magnetic coupling is achieved. Moreover, great mechanical strength can be obtained.

Next, the water surface is reset to the water level detection electrode 14c.
If the frequency falls below, the oscillation circuit section 20 oscillates again at the set oscillation frequency, the load control section 16 becomes inoperable, the relay 17 is opened, and the relay contact 17
a closes to the N and C sides again, the motor 6 stops operating, and the pulsator 4 stops rotating.

Effects of the Invention As is clear from the above embodiments, according to the present invention, a recess for accommodating the primary winding is provided at the center of the bottom of the outer tank, and the recess is provided at the center of the bottom of the outer tank to correspond to the gap between the primary and secondary windings of the rotary transformer. By making the side wall thickness thinner than the other wall thicknesses, the gap distance between the primary and secondary windings of the rotating transformer can be shortened, and at the same time, the strength of the bottom of the outer tank can be maintained. There is no eccentricity or change in the water level, and the water level detection performance is stable and reliability can be improved. Further, after the primary winding is inserted into the recess, coating with an insulating resin material can be easily performed by casting or the like, and good productivity and quality stability can be ensured.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a washing machine according to an embodiment of the present invention, Figs. 2 and 3 are sectional views showing the installation state of a rotary transformer, and Fig. 4 shows the basic configuration of a control circuit for water level detection. FIG. 2... Washing/dehydration tank, 3... Outer tank, 3a... Recess, 11... Rotating transformer, 11a, 11b...
Primary and secondary windings, 14a, 14b, 14c...
...Electrode (sensing part).

Claims (1)

[Claims] 1. A washing/dehydrating tank whose circumferential wall except at least the upper end is a non-porous wall, an outer tank rotatably housing the washing/dehydrating tank, and a detection unit for detecting water level disposed at a predetermined position of the washing/dehydrating tank. and a rotary transformer for extracting the water level detection signal from the detection section to the outside by magnetic coupling between a primary winding and a secondary winding. A recess with an opening inward of the outer tank is provided in the center of the bottom of the tank integrally with the outer tank, and the secondary winding is fixed to the washing and dehydrating tank, and the recess is connected to an oscillation circuit. accommodating the primary winding to be
A water level detection device for a dehydrating/washing machine in which the wall thickness of the side wall on the void side of the next winding is made thinner than the other walls.