JPS6141599B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water level detection device for a washing machine having a washing and dehydrating tub in which the circumferential side wall except at least the upper end is a non-porous wall, in which a small hole for dewatering is bored in the circumferential side wall. To reliably detect the water level in a washing and dewatering tank, which is not being used, with a simple configuration that does not use a pressure switch or an air trap device.

Conventionally, in single-tank automatic washing machines, an outer tank is provided outside the washing and dehydrating tank with small holes for dewatering in the peripheral side wall, and water is stored inside the outer tank for washing and rinsing operations. The water level was detected by operating a pressure switch based on changes in air pressure in an air trap installed on the lower side wall of the outer tank. However, the above-described 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.

It is also conceivable to provide a washing and dehydration tank without a small hole for dehydration, and to store water only in this tank for washing, but there have been various problems in detecting the water level in this case. For example, when water level is detected using a conventional pressure switch, an air trap is installed on the rotating shaft, making the waterway complicated and difficult to assemble.
It requires a great deal of effort and expense to maintain the accuracy of the rotating shaft.

In addition, a float with a magnet that moves up and down according to the water level is arranged in the washing and dehydrating tank, and a reed switch that is opened and closed by the float is provided, and this reed switch is installed between the washing and dehydrating tank and the bearing part. Although there is a method of connecting to a control circuit through a sliding contactor, durability due to wear of the sliding part and waterproof structure have become major problems in practical use.

The present invention has been made in view of the above-mentioned conventional drawbacks, and one embodiment thereof will be described below.

In Fig. 1, 1 is an outer frame, 2 is a washing/dehydration tank with a non-porous peripheral wall except for at least the upper end, and 3
4 is the outer tank that encloses this tank 2, and 4 is the washing and dehydration tank 2.
5 is a brake/clutch mechanism, and 6 is a motor, which transmits rotational force to the brake/clutch mechanism 5 via a motor pulley 7, a belt 8, and an impeller pulley 9. The brake/clutch mechanism 5 selectively transmits this rotational force to the pulsator 4 or the washing and dewatering tank 2.

Reference numeral 10 denotes a vibration isolating support device hanging from the four corners of the outer frame 1, which elastically suspends and supports the outer tank 3 by means of rods 10a, springs 10b, etc. 11 is a rotary transformer having an equal part, and 11a is one of the rotary transformers.
The next winding, 11b, is its secondary winding. The secondary winding 11b is fixed to the bottom of the washing/drying tub 2, and the primary winding 11a 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 and dewatering tub 2, through which washing water is guided upward and discharged by rotation of the pulsator 4. A lint filter 13 is provided in this discharge portion. Reference numerals 14a, 14b, and 14c are electrodes for detecting water level provided in the lint filtration circulation path 12, and each electrode 14a, 14b, and 14c is for detecting high water level, middle water level, and low water level, respectively.

2 and 3 show the installation state of the rotary transformer 11, and FIG. 2 shows a plurality of primary windings 11.
a and the secondary winding 11b are stacked in the directions of the washing shaft 15 and the dehydration shaft 16. Figure 3 shows 1
The next winding 11a and the secondary winding 11b are connected to the washing shaft 1.
5. It is in a state where it is provided in a plane direction perpendicular to the dehydration shaft 16 and on a concentric circle.

In both figures, each secondary winding 11b is connected to each water level detection electrode 14a, 14b, 14c via a lead wire. The primary winding 11a facing this secondary winding is connected to a control circuit.

FIG. 4 is a block diagram showing the basic configuration of the water level detection circuit, in which 17 is an AC power supply, 18 is a load control unit that controls opening and closing of energization to relay 19,
Loads such as the washing machine motor 6, water supply valve, and timer motor (all not shown) are controlled by the relay contact 19a. 20 is an amplifier circuit for amplifying a signal from an oscillation circuit section 22, which will be described later; 21 is a water level setting changeover switch; the primary winding 11a corresponds to the water level to be set;
connected to either. Reference numeral 22 denotes an oscillation circuit section which obtains an arbitrary oscillation frequency, for example 1 MHz, from the DC power supply section 23.

Next, the operation will be described. When the timer circuit of the washing machine is energized, the water supply valve operates in the water supply process, and water is supplied into the washing and dewatering tub 2. At this time, the water level detection device is also energized. At the initial stage of water supply, water is not in contact with any of the water level detection electrodes 14a, 14b, and 14c, and the resistance value between the plates of each electrode is close to an infinite value.

Therefore, in this state, the oscillation circuit section 22 oscillates at the set oscillation frequency, the load control section 18 is not operating, the relay 19 is not operating, and the relay contact 19a is closed to the NC side.

When the water level setting changeover switch 21 is connected to the middle water level, that is, b, when the water supply continues and the water reaches the position of the water level detection electrode 14c,
The water brings electrical continuity between the plates of the electrode 14c, and the rotary transformer 11 corresponding to the electrode 14c
Although the secondary winding 11b is short-circuited, the state of the oscillation circuit section 22 does not change because the primary winding 11a is open.

Furthermore, water supply continues, and the water level detection electrode 14b
When the water is supplied to the position, the water makes conduction between the plates of the electrode 14b, the secondary winding 11b of the rotary transformer corresponding to this electrode 14b becomes short-circuited, and the oscillation circuit is activated by the primary winding 11a. Since the section 22 is unable to maintain the set oscillation state and oscillation stops or the oscillation voltage drops below the reference value, the load control section 18 operates and the relay 19 operates to close the relay contact. 19a is switched to the NO side, water supply is stopped, the motor 6 is operated, the pulsator 4 is rotated, and washing or rinsing is started.

As is clear from the embodiments described above, according to the present invention, a rotary transformer corresponding to one set of electrodes for water level detection is independently provided, and a plurality of sets of electrodes and rotary transformers are further provided corresponding to a plurality of set water levels. This allows detection of open and conductive conditions (resistance between electrodes varies depending on water quality) on the secondary side of the rotating transformer, greatly improving detection sensitivity and preventing malfunctions due to water quality, improving reliability. expensive. When put into practice, a plurality of primary windings or secondary windings can be formed in the same winding frame, which simplifies the configuration. Furthermore, multiple 1
By installing the secondary winding and the secondary winding in a plane perpendicular to the washing/dehydrating axis and concentrically, the space between the washing/dehydrating tub and the outer tub can be minimized, and the washing machine The height of the main body can be lowered.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a washing machine according to an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views showing how the rotary transformer is installed, and FIG. 4 is a basic configuration of the control circuit. FIG. 3 is an electrical block diagram. 2...Dehydration/washing tub, 3...Outer tank, 11...Rotating transformer, 11a...Primary winding, 11b...2
Next winding, 14a, 14b, 14c... Water level detection electrode, 15... Washing shaft, 16... Dehydration shaft, 21...
...Water level setting switch.

Claims (1)

[Scope of Claims] 1. A washing/dehydration tank having a non-porous peripheral wall except for at least the upper end is provided in the outer tank, and an electrode for water level detection is provided at a predetermined position of the washing/dehydration tank. This is a water level detection device that extracts a water level detection signal from the
A plurality of rotary transformers having secondary windings are provided, each electrode is connected to the secondary winding of each rotary transformer that rotates together with the washing and dehydrating tank through a conductor, and the secondary winding A primary winding of each rotary transformer is provided on the outer tank side containing the washing and dehydrating tank so as to be electromagnetically coupled to the wire, and the primary winding is connected to a control circuit. teeth,
A water level detection device for a washing machine, comprising a changeover switch selectively connected to a primary winding corresponding to each set water level. 2 A plurality of rotating transformers are connected to their primary windings and 2
2. The water level detection device for a washing machine according to claim 1, wherein the secondary windings are provided so as to be stacked in the direction of the washing/dehydrating axis. 3 Connect multiple rotating transformers to their primary windings and
2. The water level detection device for a washing machine according to claim 1, wherein the secondary winding is provided concentrically and in a plane direction perpendicular to the washing/drying axis.