JPH04187183A - Washing liquid detection sensor of washing machine - Google Patents

Abstract

PURPOSE:To accurately detect the kind and concentration of a detergent and the quantity of dirt to eliminate an error in detection accuracy due to a deterioration with age by adopting a high-frequency conductivity sensor for catching the state of a washing liquid as an impedance change between electrodes, and by converting the impedance change into a voltage variation and taking the voltage variation into a microcomputer. CONSTITUTION:About 10KHz high frequency generated by a high-frequency oscillator is applied to a conductive sensor 10 via an insulating transformer 17a, a sensor-reading circuit catches the change of impedance varying with the state between electrodes 10b of the conductive sensor 10 by the variation of the primary side voltage of the insulating transformer 17a and inputs the change to a microcomputer, and the kind and state of a washing liquid within an outer tub 4 and the kind of clothing are detected by the operation for comparing the change with data stored beforehand. Thus, electric conductivities of respective laundry processes such as water supply, washing, rinsing and dehydration are measured, and respective measured values are stored in the microcomputer, compared with data programed beforehand and operated so that it is possible to control the execution time and process of each stroke and to perform the optimum laundry course.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor system for detecting the state of a washing liquid in a washing machine that washes clothes with detergent such as liquid or powder.

[Conventional technology]

Conventional sensors for detecting the concentration and dirtiness of washing liquid use optical sensors used by manufacturers of washing machines and other machines to detect the turbidity of the washing liquid and detect the condition of the washing liquid. Are known.

The structure of the optical sensor is to place a light emitting part and a light receiving part on the outside of a transparent or semi-transparent case, and detect the state of the washing liquid based on the high light transmittance due to the turbidity of the washing liquid inside the case. It is something to do.

[Problem to be solved by the invention]

The above conventional technology detects the difference in the state of the washing liquid by the turbidity of the liquid and detects it by the transmittance of light. The transmittance of the light changes sharply, making it impossible to obtain accurate measurements.

2. Just adding detergent makes the washing solution cloudy, making it difficult to determine the amount of dirt.

3. No matter how many times you rinse clothes and detergent, a small amount of surfactant remains and this liquid is stirred with a stirring blade, resulting in foaming, which reduces light transmittance and creates a cloudy state. It is determined that

There are problems such as.

An object of the present invention is to provide a washing liquid state detection sensor that can accurately detect the type of detergent, the detergent concentration, and the amount of dirt, and that is less prone to errors in detection accuracy due to aging.

[Means to solve the problem]

In order to achieve the above object, the electrodes are brought into direct contact with the washing liquid, a high frequency voltage is applied between the electrodes, and the state of the washing liquid is directly detected as a change in impedance between the electrodes.

Furthermore, the frequency of the high frequency voltage to be applied is set to 1 to 30KHz.
When considered as a washing machine, from tap water, which is the liquid to be measured, to detergent liquid with the concentration specified by the manufacturer,
It is possible to obtain a sensor for detecting the state of the washing liquid with very little variation in conductivity due to frequency fluctuations and high accuracy.

In addition, the electrodes that are directly immersed in the washing liquid and the reading circuit to the microcontroller are connected by an isolation transformer, so there is no risk of electric shock even if a part of the controller comes into contact with the 100V AC power supply. '1゜Also, by capturing the measurement voltage as the voltage on the primary side of the high-frequency isolation transformer, it is no longer necessary to use a special semiconductor element such as a photocoupler in consideration of insulation from the secondary side electrode part. It can be made into a cheap and reliable sensor.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

As shown in FIG. 1, a washing machine adopting the present invention includes a hanging rod 2 and a vibration isolator inside an outer frame 1 made of a steel plate. The outer tank 4 is suspended by 34 rods.

A washing and dewatering tank 5 is rotatably provided in an outer tank 4 for storing water during washing. The washing and dehydration tank is provided with a large number of dehydration holes 5a. A pulsator 6 for stirring the washing is disposed in the center of the washing and dehydrating tank. At the bottom of the outer tank 4 is a drive motor 7,
Clutch for switching between dewatering and washing 8. A drain valve motor 9 for actuating the clutch and opening/closing the drain valve is installed, and a high frequency conductivity sensor 10 (hereinafter referred to as conductivity sensor) for measuring the high frequency conductivity of the washing liquid penetrates the bottom side of the outer tub 4 on the bottom side wall. It is installed so as to be immersed in water approximately along the side wall of the outer tank 4.

Since the electrode 10b is configured and attached along the side wall of the outer tank 4, there is an effect that the electrode 10b is less likely to be soiled by precipitation of soap scum, dirt, etc.

The conductivity sensor 10 is made of stainless steel or brass with carbon printing applied to the surface, and an electrode part and an external connection terminal part 10c are insert-molded in a synthetic resin sensor case 10a, which is bonded to the bottom of the outer tank 4 with an adhesive 11. It has a fixed configuration.

At this time, the electrode 10b and the sensor case 10a are placed on a plane.

Also, is the height H from the bottom of the outer tank 4 to the electrode the same as the residual water level in the residual water activation method, which dehydrates a small amount of water in the outer tank in order to reduce the relative unbalance during dehydration? The height is kept below this □ and the surface of the electrode 10b of the sensor is cleaned by using the rotation of the water remaining during dehydration to keep the surface clean at all times so that accurate measurements can be made.

Furthermore, there is a dehydration hole 5 of the washing and dehydration tank at a position lower than the height H.
The configuration is such that a is not provided.

An operation panel section 13 is provided at the rear of the top cover 12, and within the operation panel 13 is provided a water supply electromagnetic valve 14 for supplying water from a faucet into the tank. The outlet of the water supply solenoid valve 14 is an in-tank water supply port 15a that directly supplies water to the washing and dehydration tank 5.
and a sensor water supply port 15b that supplies water between the outer tank 4 and the washing/dehydration tank provided on the tank cover 16 (the water supply solenoid valve 14 and the sensor water supply port 15b are connected with a flexible hose). . The conductivity sensor 10 is located substantially directly below the sensor water supply port L5b.

A water level sensor (not shown) for detecting the water level in the outer tub 4 and a control board 17 for controlling the washing machine are further disposed within the operation panel 13. As shown in FIG. 3, the control board includes, via the power switch 18, a microcomputer in charge of control, a power supply circuit, an LED display circuit, an external operation switch circuit,
Solenoid output circuit, output circuit, and conductivity sensor 1
It consists of a high frequency oscillation circuit for zero control, a sensor reading circuit, etc.

A high frequency of about 10 KI (z) generated by a high frequency oscillator is applied to the conductive sensor 1o via an isolation transformer 17a, and the voltage is applied depending on the condition between the electrodes 10b of the conductive sensor 1o (only water, detergent concentration, amount of dirt, etc.). The changing impedance is captured by the sensor reading circuit as a change in the primary side voltage of the isolation transformer 17a, and is input to the microcomputer.
The type and condition of the washing liquid in the outer tub 4 and the type of clothing are detected by comparison with data stored in advance. The voltage at the end of the detection resistor RoWJ when the oscillation frequency is changed is as shown in Fig. 4, and the most desirable range is 1 to 30 KHz, which has little change with respect to frequency fluctuations, and in this embodiment, the voltage is 1.
0 KHz was adopted.

Next, the operation of the washing machine and the control method using the conductivity sensor 1-O will be explained. Add detergent and laundry and turn on the power switch.
Set the ``Standard'' fully automatic course using the outer tank operation switch and press the ``Start'' button to execute fully automatic operation.

First, the water supply solenoid valve 14 opens to start water supply. The supplied water is branched into two parts, one of which is directly supplied to the washing and dehydrating tank 5, and the laundry is thoroughly soaked with water and detergent. On the other hand, the sensor water supply port 15b connects to the washing/dehydration tank 5.
Water is supplied between the tank and the outer tank 4. Since the conductivity sensor 10 is located substantially directly below the sensor water supply port 15b, it comes into direct contact with tap water. Water supply is almost conductive sensor 1
The water level sensor detects that the water has reached the upper end of the electrode 10b at 0, measures the conductivity at that time, and stores it in the microcomputer as the initial conductivity Vo > 3.
In this case, Vo=2.5 or the Vo value of the previous measurement. Thereby, the data measured by the conductivity sensor 10 due to differences in hardness, temperature, and components of tap water can be corrected and accurate control can be performed. Next, when the water supply reaches the specified cloth amount sensing water level, the water supply is temporarily stopped.
In order to detect the amount of clothes and determine the set water level, a cloth amount sensing process is performed in which the clothes are stirred for about 30 seconds. After the cloth amount sensing process is completed, the conductivity Tw of the washing liquid is measured and this value is stored in the microcomputer. Next, water is supplied to the water level automatically set by cloth amount sensing, and the initial stirring conductivity Vl after stirring for 1 minute is measured and stored in the microcomputer. Furthermore, the conductivity Vt immediately before the end of washing and stirring is measured.

When the washing is completed, the first rinsing drain and dewatering steps are executed, then the rinsing water supply is started, and when the water supply reaches the specified water level, the rinsing agitation is executed.

The conductivity V sl of the first rinse immediately before the end of rinsing and stirring is measured and stored in the microcomputer. Next, a second rinsing step is performed. In the second rinsing step, the same process as the first rinsing step is performed, and the rinsing wave conductivity VS2 immediately before the end of rinsing and agitation is measured and stored in the microcomputer. Once the rinsing is complete, the final dehydration process begins. During spin-drying, water contained in the laundry is forced out into the outer tub 4 due to mental force, descends along the wall of the outer tub 4, and reaches between the electrodes of the conductive sensor 10. As the spin-drying time elapses, the amount of water coming out of the laundry gradually decreases, and the time for the conductivity vD during spin-drying to be approximately the same value as air or the sensor case 10a becomes gradually longer. Measure time T.

As described above, the electrical conductivity in each washing process of water supply, washing, rinsing, and spin-drying is measured, each value is stored in the microcomputer, and by comparing and calculating with pre-programmed data, each process can be determined as follows. The execution time and process can be controlled to execute the optimal washing course.

When a standard course is set, the amount of cloth is sensed, and the water level is set, a standard course is determined according to the amount of cloth that has been programmed in advance. Now, when the cloth amount is 4.0 and the high water level is set, it is "9 minutes of washing, 1st rinse, 2 minutes of dehydration, 2 minutes of stirring,
2.5 minutes of rinsing, 2.5 minutes of dehydration, 2.5 minutes of stirring, and 5 minutes of dehydration.

1.1 Changing the washing time depending on the type of detergent Current liquid detergents have minimal changes compared to the conductivity of water. Other powder detergents have large changes, so the detergent concentration at the water level at the time of cloth amount sensing, which is lower than the set water level. Electrical conductivity when Vw-V is high
Calculate o=Vwo and change the washing time based on the determination shown in FIG.

2. Changing the washing time depending on the method of adding detergent Powdered detergent dissolves easily depending on the method of adding it.If it is dissolved in water in advance or if it is added to the bottom of the tank, it dissolves easily;
If the detergent is added to the upper part of the clothes, it will not easily dissolve, so the calculation of Vz-Vw=Vtw is performed, and the method of adding the detergent is detected based on the determination in FIG. 6, and the washing time is changed.

3. Changing the washing time depending on the amount of dirt (large or small) Since the current level of the washing liquid changes depending on the amount of dirt, calculate Vl - Vz = Vtz and detect the degree of dirt using the judgment shown in Figure 7. death,
Change wash time. However, the comparison data of Vwl at this time shall be kept for each water level.

4. Changing the rinsing method depending on detergent solution concentration (including soiling condition) and type of clothing When the same rinsing method is performed, the final rinsing solution concentration differs depending on the initial detergent concentration and the type of clothing to be washed. That is, for the same type of clothing, if the detergent concentration is high, rinsing may not be sufficient, and if the detergent concentration is weak, rinsing may be too much (wasting water). In addition, when the detergent solution is the same, in the case of cotton clothes, the detergent does not easily remove the detergent, so it is necessary to rinse thoroughly, while in the case of fabrics, the detergent does not easily remove, so just rinsing lightly will result in sufficient rinsing. Become.

By detecting the conductivity of the rinsing agitation liquid and rinsing until it reaches a predetermined concentration or less, satisfactory rinsing can be achieved by optimizing the rinsing method according to the concentration of the washing liquid and the type of clothing. It is something.

Concerning the conductivity VSIO, Vszo of the rinsing stirring liquid and the control method: - The control for the first rinse is shown in Figure 8. The control for the second rinse is shown in Figure 9.

If the conductivity V s20 measurement result just before the end of the second stirring is determined to be insufficient rinsing and 2 minutes are added to the water pouring rinse, the conductivity is measured again after 2 minutes of water pouring and if it is determined that rinsing is insufficient. An even more satisfactory rinse can be achieved by adding 2 minutes of water pouring. When the two water injection rinses are completed, regardless of the degree of rinsing, the process will proceed to the final dehydration, which will prevent malfunction of the conductivity sensor 10,
This prevents the use of a large amount of waste water due to malfunction.

5. Changing the spin-drying time depending on the type of clothing (cotton, cotton, etc.) Consider the spin-drying time depending on the quality of the clothes to be washed. can be improved. In addition, for woven fabrics and blended fabrics that have good desorption properties, the dehydration rate tends to be saturated after a short dehydration time. The quality of clothing can be determined more accurately by taking the difference V, 5t = Vz - Vs1 between the electrical conductivity V□ just before the end of washing and the electrical conductivity Vs1 just before the end of the first stirring of the first rinse. Based on this data, the final dehydration time is determined, and the optimal dehydration time is automatically set to improve the dehydration rate for cotton, and to obtain the highest dehydration rate with less wrinkles and less wrinkles for cotton and blended fabrics. .

FIG. 10 shows the dehydration time depending on the value of conductivity Vist.

6. Quantity of laundry (9 types) Correcting spin-drying time due to mechanical loss, etc. The spin-drying time is determined by the type of clothing in item 5, but in reality, the time required to reach constant speed rotation depends on the amount of laundry, mechanical loss, etc. are different, and there is a difference in the actual dehydration time, so it is necessary to correct the required dehydration time. As a correction method, the flow of water during dehydration is detected by the conductivity sensor 10 using the method described above, and the time T during which the conductivity Vo≧1 is measured is measured.

By determining that the dehydration rate is almost stable when T becomes longer than 20 seconds, and dehydrating for +2 minutes from that state,
It becomes possible to obtain the optimum dehydration state in the minimum necessary time.

〔Effect of the invention〕

1. According to the present invention, since the electrical conductivity of the washing liquid is measured using the optimum high frequency of 1 to 30 KHz, it is possible to provide a highly accurate sensor with less variation in constant data.

(2) Since the voltage changes due to differences in the state of the washing liquid can be large, changes can be detected even if the electrodes are placed far enough in front of each other, so malfunctions due to dirt or soap scum adhering between the electrodes during long-term use can be detected. It can be prevented.

2. According to the present invention, since the sensor electrodes and the microcomputer reading circuit are connected by an isolation transformer, the sensor can be highly safe without fear of electric shock.

3. According to the present invention, since fluctuations on the primary side of the isolation transformer can be input directly to the microcomputer, there is no need for insulation and the configuration can be made cheaper compared to the case where the impedance between the secondary side electrodes is read.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a washing machine equipped with one embodiment, Fig. 2 is a cross-sectional view taken along A-A of the washing liquid state detection sensor, Fig. 3 is a controller block circuit diagram, and Fig. 4 is an applied voltage frequency and conductivity. FIG. 5 to FIG. 10 are diagrams showing an example of a sensor control method in each washing process.

Claims (1)

[Claims] 1. As a sensor for detecting the detergent concentration, degree of dirt, etc. in the washing liquid of a washing machine, electrodes are immersed in the washing liquid and a high frequency voltage of 1 to 30 KHz is applied between the electrodes. A washing liquid detection sensor for washing machines that uses a high-frequency conductivity sensor that detects the state of water as an impedance change between electrodes, converts the impedance change into a voltage change, and inputs it to a microcontroller. 2. A washing liquid detection sensor for a washing machine according to claim 1, characterized in that a washing liquid state detection sensor (high frequency conductivity sensor) and a reading circuit for a microcomputer are connected via a high frequency isolation transformer. . 3. A washing liquid detection sensor for a washing machine, characterized in that the voltage change measured in claim 1 is detected as a voltage change on the primary side of a high frequency isolation transformer.