JP2511938B2 - Water level converter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water level conversion device for detecting a water level in a device such as an electric washing machine or an electric dishwasher.

2. Description of the Related Art A general principle of water level detection will be described with reference to FIGS. FIG. 2 is a cross-sectional view of a displacement detector that converts a change in pressure proportional to the water level into a change in coil inductance, and FIG. 3 is an electric circuit of an oscillator circuit that converts a change in coil inductance into a change in frequency. It is a figure. In FIG. 2, P is a pressure proportional to the water level, and this pressure P is received by the thin film diaphragm 15 formed of rubber or the like. A ring-shaped coil 16 is provided in the displacement detector,
The magnetic body 17 fixed to the diaphragm 15 moves up and down in response to the pressure P to move up and down in the coil 16. 18
Is a spring for suppressing the displacement of the magnetic body 17, 19 is an adjusting screw, 20 is the circumference of the diaphragm 15 and the coil 16, the adjusting screw 19
The coil 16 is a part of the oscillation circuit shown in FIG. In FIG. 3, 21
Is an inverter, 22 is a feedback resistor, and 23 and 24 are capacitors.

In the above-described structure, when the pressure P proportional to the water level applied to the diaphragm 15 changes, the magnetic body 17 causes the spring 18 to move.
Is displaced in the vertical direction by the action of. At this time, the coil
Since the magnetic body 17 is displaced inside the coil 16, the inductance of the coil 16 changes. Since the frequency of the oscillator circuit is determined by the inductance of the coil 16 and the capacitance of the capacitors 23 and 24, the frequency changes when the inductance of the coil changes. The relationship between the water level and the frequency is shown in the graph of FIG. In the figure, the relationship between the water level and the frequency is one-to-one, so if a certain water level is to be detected, it suffices to detect the frequency at that time.

Problems to be Solved by the Invention However, when the ambient temperature used changes,
In mass production, diaphragm 15, coil 16, magnetic material
When the characteristics of 17, spring 18, capacitors 23 and 24, etc. vary, the relationship between water level and frequency is as shown in FIG. In the figure, g represents the upper limit of the variation, h represents the lower limit of the variation, and i indicated by a broken line is its center line. Here, when the water level h is 0 ≦ h ≦ h _{b and} h = h _b , the minimum variation is that the adjusting screw 19 adjusts the frequency f = f _b when the water level h = h _b at room temperature. This is for adjustment. In the case where the relationship between the water level and the frequency fluctuates in this way, for example, if it is detected that the frequency becomes f _a while trying to set the water level to h _a , the actual water level becomes h
There is a problem that the variation is large from _a1 to h _a2 , especially at a low water level.

Then, this invention solves the said conventional problem, and an object of this invention is to provide the water level conversion apparatus which can implement | achieve highly accurate water level detection even at low water level.

Means for Solving the Problems In order to achieve this object, the water level conversion device of the present invention is
A water level detection unit that detects a water level adjusted to output a predetermined electric signal with respect to the maximum water level in advance and converts it into an electric signal, and the upper limit, average, and lower limit water level detection characteristics of the variation of this water level detection unit are stored. Then, the control means has a control means for controlling the entire equipment. The control means controls the water level detection means to determine the water level determination frequency f _e ′, and the frequency f _0x when the water level is 0 is the average frequency f _0c. In the above case, f
_e ′ == _{fe c} + (f _0x −f _0c ) A, and when the frequency f _0x when the water level is 0 is equal to or higher than the variation average frequency f _0c , _fe ′ = f _ec − (f _{0x -F0c} ) A is used for the calculation. Further, in the water level conversion device, the range of variation in the value of the water level detecting means when the water level is 0 is divided into a plurality of ranges, and when the water level is 0, an average water level characteristic having a detection frequency in each range is obtained. It is also possible to have a configuration in which the value of a desired water level is calculated by the water level characteristic corresponding to the detected frequency when the water level is 0, which is stored in the control means.

Action With the above configuration, the water level can be corrected to 0 for the correction of the value related to the variation of the ambient temperature and the variation of the individual water level detection devices during mass production.
Since it is performed at the time of, it is possible to realize highly accurate water level detection even at a low water level.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of essential parts when the present invention is applied to a fully automatic washing machine, FIG. 4 is a characteristic diagram for explaining a method of calculating a frequency corresponding to a desired water level, and FIG. 5 is an actual water supply. It is a principal part flowchart which shows operation | movement. In FIG.
Reference numeral 1 is an input means for setting the washing time, the number of rinses, the dehydration time and the like, 2 is a display means for informing the user of the contents set by the input means 1 and the current progress status, and 3 is a water level detection means. Water level detecting means 5 and 6 for converting it into frequency data are bidirectional thyristors for driving the washing and dehydrating motor 13, 7 is a bidirectional thyristor for driving the water supply valve 12, and 8 is a drain magnet 11 , 8 is a commercial frequency power source, 10 is a power switch, 14 is a phase advancing capacitor, 4 stores a predetermined frequency, and frequency data output from the water level detection means 3 is input. It is a control means for calculating a determination frequency corresponding to a desired water level and controlling the entire device. The structure of the water level detecting means is as shown in FIG. 2 and FIG. 3, which is the same as the structure of the conventional example.

An actual water supply operation in the above configuration will be described with reference to the characteristic diagram of FIG. 4 and the flowchart of FIG. In FIG. 4, the characteristics indicated by the broken line a are the characteristics of an average sample when the water level detecting means is varied or when it is affected by the ambient temperature, b is the characteristic of the upper limit sample, and c is the characteristic thereof. It is the characteristic of the lower limit sample, and x represents the characteristic of a certain sample.

For example, a sample having a characteristic of x is used as the water level detecting means, and considering that water is supplied up to the water level of h _e , first, at step 400, the water level detecting means 3 makes
At this time, the initial frequency f _0x is measured. Then step 401
The frequency f _0c stored in is compared with the initial frequency f _0x ,
If f _0x ≧ f _0c , the determination frequency is calculated in step 402, and if f _0x <f _0c , the determination frequency is calculated in step 403. Where f
_0c is the frequency when the average water level of the sample is zero. In FIG. 4, the desired water level is h _e , the frequency f _0h when the water level of the sample whose variation is the upper limit is 0, and the frequency when the water level of the sample whose variation is the lower limit is 0 are f
_{If 0l} and (f _0h -f _0c ) or (f _0c -f _0l ) are 1, then proportional calculation (f _eh -f _ec ) or (f _ec -f)
_el) becomes _{(h h -h e) / h} h (= to A). Here f _ec, f _eh, f _el is the average sample, the variation upper limit of the sample, variations in the sample the lower limit frequency when the water level respectively h _e. Step 402 or Step 4
The proportional calculation as described above is performed in 03, and when f _0x ≧ f _0c , the determination frequency f _e ′ = f _ec + (f _0x −f _0c ) × A, f _0x <
When f _0c , f _l ′ = f _lc + (f _0c −f _0x ) × A.
Then, in step 404, the water supply valve 12 is turned on to start water supply,
After a certain time delay in step 405, the water level detecting means 3 measures the frequency f _x in step 406. In step 407, the measured frequency f _x is compared with the judgment frequency f _l ′, and f _x
If> f _l ′, the process returns to step 405, and if f _x ≦ f _l ′, it is considered that the desired water level has been reached, and the process goes to step 408 to turn off the water supply valve 12 and terminate the water supply operation.

Furthermore, FIGS. 6 and 7 show another embodiment of the present invention.
This will be described with reference to the drawings. The configuration is the same as that of the first embodiment, but the control means 4 stores the comparison frequencies f ₀₁ and f ₀₂ . In FIG. 6, the frequency is f _0l when the water level is 0 due to variations in the water level detection means and the influence of the ambient temperature.
To f _0h, the characteristics of the water level h and the frequency f are divided into three regions, which are d region, e region, and f region.
The frequencies f _ld , f _le , and f _lf are the frequencies of samples showing the central characteristics of the d region, the e region, and the f region, respectively, when the water level is h _e . Here, considering water supply up to the water level of h _e, the water supply operation will be described with reference to the flowchart in FIG. 7. First, in step 400, the water level is 0 by the water level detection means 3.
At this time, the initial frequency f _0x is measured. Where f _0x ≧ f ₀₁
If so, it is determined that the water level detecting means has a characteristic of the d region, and in step 409, the determination frequency f _l ′ = _fl d is set.
Similarly, if f ₀₂ ≦ f _0x <f ₀₁ , then f _f ′ = f _le is set in step 410, and if f _0x <f ₀₂ , f _l ′ = f _lf is set in step 411. The following steps 404 to 408
Up to this point, the description is omitted because it is similar to the first embodiment.

In this embodiment, the water supply of the fully automatic washing machine is described, but the invention can also be applied to an apparatus such as an electric dishwasher accompanied by a water supply operation. Furthermore, the displacement detection unit of the water level detection means
The variable inductance method, which converts pressure changes proportional to the water level into changes in the coil inductance, was used as a variable capacitance method that converts pressure changes proportional to the water level into changes in the capacitance of the capacitor. The same effect can be obtained as the water level detecting means connected to the oscillation circuit.

Further, although the water level detection is changed by the frequency change, the same effect can be obtained even if the voltage value or the current value is changed according to the water level.

EFFECTS OF THE INVENTION According to the present invention, with the above-described configuration, the control unit is used to correct the error of the water level detection unit (adjustment of variations in the output value), and thus the configuration of another device for correction is not required. Further, since the water level is detected without changing the detection accuracy of the water level detection means itself and without changing the detection range, the accuracy is not lowered. Furthermore, since the detection means with lowered detection accuracy is not forced to correspond to the detection range and the error of the device of the detector is enlarged and output,
It can be detected accurately. In particular, this tendency is strong in the low water level range where accuracy is required, and the low water level can be accurately detected.

Furthermore, since the conversion is performed based on the value when the water level is 0 after the water level detection means is assembled, highly accurate water level detection can be realized irrespective of ambient temperature changes and variations in the water level detection device solids that occur during mass production. it can.

[Brief description of drawings]

FIG. 1 is a block diagram of a fully automatic washing machine according to an embodiment of the present invention, FIG. 2 is a sectional view of a displacement detecting portion of water level detecting means, and FIG.
FIG. 4 is an electric circuit diagram of the oscillator circuit, FIG. 4 is a characteristic diagram of water level and frequency in one embodiment of the present invention, FIG. 5 is a flow chart showing processing by the control means, and FIG. Fig. 7 is a characteristic diagram of water level and frequency in the embodiment of Fig. 7, Fig. 7 is a flow chart showing processing by the control means, Fig. 8 is a characteristic diagram of general water level detection means, and Fig. 9 is a conventional water level detection method. It is a characteristic view of water level and frequency. 3 ... Water level detection means, 4 ... Control means.

Claims (2)

(57) [Claims] 1. A water level detecting means for detecting a water level adjusted in advance to output a predetermined electric signal with respect to a maximum water level and converting the water level into an electric signal, and an upper limit, an average and a lower limit of variations of the water level detecting means. a controlling unit for controlling the entire apparatus stores the water level detection characteristic, the control means determines the frequency f _e 'of the water level of the water supply stopped by the water level detecting means, the frequency f _0x when the water level is zero variation When the average frequency is f _0c or more, f _e ′ = f _ec + (f _0x −f _0c ) A is calculated,
The frequency f _0x when the water level is 0 varies and the average frequency f 0
When less than _{0c, f e '= f ec} - (f 0x -f 0c) level converter that calculated in A. f _ec: average frequency A when the water level h _e: the upper limit value f _0h frequency variation when the water level = 0, the average value f _0c, the lower limit value is set to f _0l, (f _0h -f _0c ) Or (f _0c -f _0l ) is 1 and means (f _eh -f _ec ) or (f _ec -f _el ). However these are by proportional calculation becomes _{(h h -h e) / h} h. Here, h _h is the water level for adjusting the water level detecting means. 2. A range of variation of the value of the water level detecting means when the water level is 0 is divided into a plurality of ranges, and when the water level is 0, an average water level characteristic having a detection frequency in each range is provided to the control means. The water level conversion device according to claim 1, wherein the water level conversion device stores a desired water level value based on a water level characteristic corresponding to a detection frequency when the water level is zero.