JPS5934397B2 - Washing machine rinse detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rinse detection device for an electric washing machine.
The conductivity of the cleaning liquid in the cleaning tank and the detergent-free water used for cleaning is detected by a resistor connected in series with the electrode pair or by the voltage across the electrode pair, and the difference is calculated. The purpose is to perform highly accurate rinsing detection by comparing the value with a reference value.

General cleaning liquid in the cleaning tank (hereinafter simply referred to as cleaning liquid)
It is well known that there is a certain correlation between detergent concentration and conductivity.

The relationship between the detergent concentration and the conductivity is shown in FIG. 1, using the conductivity of water such as tap water supplied into the cleaning tank as a parameter.

In Fig. 1, characteristic A corresponds to the case where the conductivity of detergent-free water supplied into the cleaning tank is 4450μ/cm;
6O is the same (in the case of 1560, μU/cm, C is 50
In the case of 01zhi7cm, D is 1501tU/Crl1
Each case is shown below.

As is clear from each characteristic, when trying to detect a certain concentration of detergent, the conductivity at that time varies depending on the conductivity of the detergent-free water (hereinafter simply referred to as water) supplied into the cleaning tank. It is clear that there are differences, and therefore corrections for water quality, such as tap water, are necessary.

In other words, if the electrical conductivity of water is ρW (/17 J/cm), the electrical conductivity of the cleaning liquid is ρ (tt7 J/crri), and the detergent concentration η is the same, then (ρ-ρw = Kη (K is a constant...・・・・・・
...There is a relationship of ■.

Therefore, by detecting (ρ-ρW), the detergent concentration of the cleaning liquid can be detected.

The present invention satisfies the rinse detection performance of a washing machine by accurately detecting (ρ-ρW), and one embodiment thereof will be described below with reference to the drawings.

As shown in FIG. 2, 1 is a rotary blade driven by a morph 2 to generate a water flow, 3 is a cleaning tank, and 4 is a cleaning/dewatering tank.Water is supplied to the cleaning tank 3 by a water supply valve 5.

6 is a pair of electrodes provided so as to be immersed in the water coming out from the water supply valve 5;
Reference numeral 7 designates a pair of electrodes provided so as to be immersed in the cleaning liquid, each of which is connected to a rinse detection circuit 8.

Next, the configuration of the rinse detection circuit 8 will be explained with reference to FIG.

Resistors 9 and 10 are connected in series to the electrode pairs 6 and 7, respectively, and a differential amplifier 11 whose two inputs are the voltages across each resistor 9 and 10 is connected to the output of the differential amplifier 11. It has a comparator 12 for comparing the value with a reference value.

In the above configuration, the electrode pair 6, 7 and the resistor 9 are connected in series.
, 10, the output voltage of the differential amplifier 11 is expressed as follows.

The conductivity of the water is ρW (μU/CTL), the conductivity of the cleaning liquid is ρ (μU/CrrL), the values of the resistors 9 and 10 connected to the electrode pairs 6 and 7, respectively, are r (Ω), and the difference is When the amplification factor of the dynamic amplifier 11 is A, the output voltage of the differential amplifier is V.

In the equation (2), C is a constant and varies depending on the shape and material of the electrodes composing the electrode pair 6 and 7. R8 is the equivalent resistance between the electrodes, and ρ is the conductivity of the liquid.

Then R8-Cρ.

There is the following relationship. Now, as is clear from Figure 1, 1 becomes, and substituting the equations ■ and ■ into the equation (■) results in .

Here, V, A, and r are constants, so if we write ■・A−r=, then if R>>r, R>>r, then vo becomes (ρ -ρW), the detergent concentration of the cleaning liquid can be detected by VO.

Here, in order for formula 0 to hold true, R>>rtl(>>r
The following conditions are necessary; if r is too large, the detergent concentration detection error will become large, which is inappropriate.

In other words, the value of r to obtain necessary and sufficient performance as a rinse detection circuit for an electric vacuum cleaner is 4000 for an electrode pair of 6°7.
If the equivalent resistance value at both ends of the electrode pair when immersed in a liquid with a conductivity of (μ7J 7cm) is Rm, then r<:(JT
-1) It has been found that the range of Rm is sufficient, and below, r<(υd−1)Rm will be explained.

The conductivity of water varies greatly depending on the region and season, and in Japan it ranges from 50 (μU/c/rL) to 4000 (1t7
J/CrrL) and a wide range.

In addition, the detergent concentration at the end of the second rinse in a normal cleaning process is generally about 0.003 to 0.0045%, and from a practical standpoint, a detergent concentration of 0.0045% is sufficient. be.

50 (μU/crrL) to 4000 (μU/cnL)
) in the water quality range 2, 0.003 to 0.0045%
Considering that it is sufficient to be able to detect the detergent concentration of
When determining the error due to the value r of the resistor 9°10 connected in series to the electrode pair 6, 7, the error ε is as follows from the equation (2) and the [phase] equation.

Here, R changes depending on the concentration of detergent, so if ε is collected by R, it becomes, and since r > O, R, > 0, R> O, :H<O, and ε is It is monotonically decreasing.

Also, from the formula (2), since R<R, ε is maximum when R−R.

The maximum value 'max of error ε is obtained by substituting R-Rw into the @formula, and furthermore, since R>0 and r>0, GeMO is obtained, and ε is monotonically decreasing with respect to Rw.

Therefore, when 1, Rw is the minimum, the error ε is maximum.

As mentioned above, the water quality is usually 50 (/zU)/
cx ) ~ 4 o Since it is necessary to consider OO (μU/CIrL), the maximum value of the equivalent resistance R of the electrode pair should be taken into account when the electrode pair is immersed in a liquid of 4000 (μ7J/c111). Bye.

In addition, the practical detergent concentration at the end of rinsing is 0.003%.
Since it is necessary to consider the ~0.0045 factor, the standard value is set to 0.
．． 003%, the error should be ±50% or less.

Therefore, by substituting ε<0.5 into the equation 0, we get and solve this inequality. Therefore, the conductivity detection circuit for detecting rinsing in an electric washing machine has a resistor 9 in series with the electrode pair 6 and 7. . μ7J/CTL)
The equivalent resistance value of the electrode pair when immersed in the liquid (v'2-1
), the performance is sufficiently satisfactory.

2. In the example, the conductivity was detected by detecting the voltage across the resistor in a series circuit of the electrode pair and the resistor. However, even if the voltage across the electrode pair is detected, Similar rinsing detection can be performed.

In addition, in the example, two pairs of electrodes are used to detect the conductivity of the water coming out of the water supply valve with one pair of electrodes, and the conductivity of the washing liquid in the washing tank is detected with the other pair of electrodes. However, it is possible to detect both of the above conductivities using only one pair of electrodes. For example, it is possible to detect both of the above conductivities using only one pair of electrodes. , we focused on the fact that the detergent was not mixed in the water, first detected the conductivity of this water, and with this value memorized, we continued to stir the cleaning items and then the detergent was mixed. Detects the conductivity of washing liquid,
From this point on, the desired objective can be achieved by using a means for extracting the difference in conductivity, a comparison means for comparing the output from this means with a reference value, as in the present embodiment.

That is, in the present invention, electrode pairs may be provided to detect the conductivity of each of the detergent-containing washing liquid and the detergent-free water.

In addition, although this embodiment describes a one-type vacuum cleaner in which a cleaning and dewatering tank is housed in the cleaning tank, this embodiment also applies to a two-tub type washing machine in which cleaning and dewatering are performed in separate tanks. The same effect can be obtained.

As described above, according to the present invention, the degree of rinsing of a vacuum cleaner can be detected with high precision using a very simple conductivity detection circuit that only has a pair of electrodes connected in series with a resistor. There is no excess or shortage of rinsing, there is no wastage of water, time, electricity, etc., it is economical, and a stable degree of rinsing can always be obtained, so its industrial value is extremely large.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between detergent concentration and conductivity using the conductivity of detergent-free water as a parameter, Figure 2 is a schematic cross-sectional view of a vacuum cleaner according to an embodiment of the present invention, and Figure 3 is its FIG. 3 is a rinse detection circuit diagram. 6.7... Electrode pair, 8... Rinse detection circuit, 9.10... Resistance.

Claims (1)

[Claims] 1. Two series circuits consisting of a pair of electrodes for detecting the conductivity of cleaning liquid containing detergent and rinsing water without detergent, and a resistor connected in series to each pair of electrodes. A power supply that supplies current to these series circuits directly in parallel, and means that is connected between the electrode pairs and the resistors of the two series circuits and detects the voltage of the electrode pairs or the resistors to obtain the voltage difference. A rinse detection device for a washing machine, wherein the resistance value is (v'2-1) times or less the equivalent resistance value between the electrodes when the electrode pair is immersed in a liquid with a conductivity of 4000 μU/CIrL. .