JPH0425840B2 - - Google Patents

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a washing machine.

(b) Conventional technology Conventionally, in response to changes in the water level in the washing tub, a magnetic material is moved in and out of a coil to change the inductance of the coil, and the change in the water level is detected based on the change in the inductance of the coil. The thing is
This is disclosed in Japanese Patent Application Laid-open No. 60-202312.

FIG. 6 shows the correlation between the inductance change of the water level detection means and the water level, which corresponds to the change in the oscillation frequency. As can be seen from this figure, if the oscillation frequency is detected, the corresponding water level can be detected.

(c) Problems to be solved by the invention In the conventional example, its characteristics change depending on the ambient temperature as shown in Figure 6. Even if you try to detect the corresponding oscillation frequency (22, 85KHz), if the ambient temperature is 5℃ or -10℃, the characteristics will be as shown by the dotted line or the dashed line in the same figure, and the water will overflow from the overflow port before reaching 22, 85KHz. The problem is that the high water level cannot be detected and water continues to be supplied no matter how long it takes.

Further, there is no problem if the magnetic material and the capacitors and coils constituting the oscillation circuit are used with extremely high precision in advance to reduce the influence of temperature, but this becomes expensive in terms of cost.

SUMMARY OF THE INVENTION In view of such problems, it is an object of the present invention to enable a washing machine to perform a water supply operation satisfactorily even if an output error occurs in a water level detection device due to the influence of ambient temperature.

(d) Means for Solving Problems The washing machine of the present invention includes a washing tub having a water overflow port at the top, a means for supplying water into the washing tub, and a signal corresponding to a change in the water level in the washing tub. A water level detection device that sequentially outputs output and whose output changes depending on the ambient temperature, and a control means that detects an output corresponding to a specified water level from the water level detection device and controls the operation of a load such as the water supply means, The control means stops water supply when the output of the water level detection device becomes approximately constant before detecting the output corresponding to a specified water level from the water level detection device when water is being supplied into the washing tub. It instructs them to do so.

Here, the water supply means refers to a means for opening and closing a water supply channel such as a water supply electromagnetic valve, and the control means refers to a microcomputer.

(e) Effect In other words, the output of the water level detection device changes depending on the surrounding temperature, so if the output of the water level detection device becomes almost constant during water supply, the output characteristics will change depending on the temperature. , the specified water level cannot be detected and the water supply is stopped, assuming that the water level has already reached the overflow level.

(e) Examples Embodiments of the present invention will be described based on the drawings.

In FIG. 2, 1 is a machine frame, 2 is an operating section provided at the upper rear of the machine frame 1, 3 is an outer tank installed inside the machine frame 1, 4 is installed inside the outer tank 3, 5 dehydration holes around
6 is a rotary blade disposed at the bottom of the washing tub 4, and 7 is a drive motor, which is connected to the washing tub 4 and the rotary blade 6 via a power transmission mechanism 8, and when washing The rotary blade 6 is rotated, and both the washing tub 4 and the rotary blade 6 are rotated at high speed during dewatering. 9 is a drain port provided at the bottom of the outer tank 3, 10 is a drain electromagnetic valve, 11 is a drain pipe, 12 is an air trap provided at one corner of the bottom of the outer tank 3, and a pressure hose is connected to the water level sensor 13 in the operating section 2. It communicates via 14. 15 is a water supply solenoid valve provided in the water supply channel 16;
7 is an overflow port provided at the upper part of the outer tank 3, and 18 is an overflow pipe, which is connected to the drain pipe 11.

Here, the water level sensor 13 will be explained.

In Fig. 3, 13a is a plastic case, and the inside is connected to the primary side 1 by a diaphragm 13b.
3c and a secondary side 13d. A pressure introduction pipe 13e is formed on the primary side 13c, and the pressure hose 14 is connected thereto. A core-shaped magnetic body 1 is provided on the secondary side 13d of the diaphragm 13b.
9 is attached, and the air trap 12
The diaphragm 13b moves inside the coil 20 and changes the inductance of the coil 20 in accordance with the movement of the diaphragm 13b as the internal pressure changes. As shown in FIG. 4, the coil 20 constitutes an oscillation circuit 23 together with capacitors 21 and 22, and the oscillation frequency changes as the inductance of the coil 20 changes. This signal is shaped and amplified by the buffer amplifier 24, and is input as a pulse signal to a microcomputer to be described later. The microcomputer determines the current water level from the input oscillation frequency signal (pulse signal). In this example, the number of pulses input within a certain period of time (for example, 1 second) is counted,
Judgment is based on the number. By doing so, changes in the water level in the tank can be detected over a wide range and continuously. Note that the water level sensor 13 and the oscillation circuit 23 constitute a water level detection device 25.

Such a fully automatic washing machine is controlled by a microcomputer, hereinafter referred to as microcomputer 2.
6 (hereinafter referred to as microcomputer) will be explained based on FIG. 5.

The microcomputer 26 includes a CPU 27, a RAM 28,
It is composed of a ROM 29, a timer 30, a system bus 31, and input/output ports 32-37. Said
The CPU 27 is composed of a control section 38 and an arithmetic section 39. The control section 38 takes out and executes instructions, and the arithmetic section 39 receives control signals from the control section 38 during the instruction execution stage. Performs arithmetic processing such as binary addition, logical operations, increase/decrease, and comparison on data provided from input devices and memory. The RAM 28 is for storing data regarding the washing machine, and the ROM 29 is for storing data related to the washing machine.
The means for operating the washing machine, the setting of conditions for judgment, the rules for processing various information, etc. are loaded in advance.

The input ports 32 to 34 receive signals from the input key circuit 38 made up of the various operation keys, the water level detection device 25, and the top lid safety switch 39 that communicates with the opening/closing of the top lid. From the output ports 35 to 37, the
An LED drive circuit 40 consisting of a group of LEDs, a buzzer circuit 41 for process end notification or abnormality notification, a load drive circuit 42 consisting of a bidirectional thyristor, etc.
A control signal is sent to the The load drive circuit 4
2 is a left and right rotation circuit 43 of the rotor blade drive motor 7 according to a control signal from the microcomputer 26;
44, controls the operation of the water supply solenoid valve drive circuit 45 and the drainage solenoid valve drive circuit 46. 47 is a power supply circuit that supplies voltage to the microcomputer 26, and 48 is a reset circuit.

The operation based on such a configuration will be explained according to the flowchart of FIG.

The output of the water level detection device 25 exhibits characteristics as shown by the solid line in Figure 6 at a temperature of 20°C, and experiments show that it outputs 23.2 KHz at medium water level and 22.85 KHz at high water level. do. In the ROM 29 of the microcomputer 26, oscillation frequencies corresponding to each of these water levels are stored.

When water is supplied into the washing tub 4, the oscillation frequency signal input from the water level detection device 25 decreases as the water level rises. When the microcomputer 26 detects an input signal of 23.2 KHz, if the set water level is a medium water level, the microcomputer 26 stops the water supply and moves to the washing or rinsing process. If the set water level is high, water supply will be stopped when a 22.85KHz input signal is detected.

Now, FIG. 1 shows control when detecting a high water level. When the water supply is started, the microcomputer 26 simultaneously measures the oscillation frequency corresponding to the water level (S-1), and sequentially updates the oscillation frequency data from the time when the water level becomes 23.2KHz or less (S-1). S-2), under normal measurement conditions, (S-2)
In -3), the latest oscillation frequency data should be smaller than the previous data, so continue measuring (updating) the data.
22. Stop the water supply when it reaches 85KHz (S-
4).

Next, in (S-3), the oscillation frequency data may not change. This is because, as can be seen from FIG. 6, the magnetic material, coil, capacitor, etc. that constitute the water level detection device 25 are affected by the ambient temperature, and as a result, the characteristics of the oscillation frequency change. (dotted line in the figure), the oscillation frequency reaches a high water level at 23KHz, and at -10℃ (dotted chain line in the figure), the oscillation frequency reaches a high water level at 23.2KHz. Therefore, to detect high water level, 22,
If an oscillation frequency of 85KHz is used as a guideline, depending on the ambient temperature, there is a risk that the overflow level will be reached before 22 or 85KHz is detected, and water will overflow from the overflow port 17 (for example, there is a difference in temperature between Hokkaido and Okinawa). The temperature can reach over 20 degrees, so the above-mentioned concerns are very likely to occur).

When the water supply reaches the overflow level, the abnormal water level will not rise and water will continue to be supplied until the user notices it, so in (S-3), if the oscillation frequency does not change for 1 second, Due to a detection error due to temperature changes, it is determined that the water level has already reached the overflow level, and the water supply is immediately stopped (S-4).

FIG. 7 shows the structure of a semiconductor pressure sensor 49 which is another example of the water level detection device 25 of this embodiment.

A silicon pellet 51 serving as a diaphragm is glued to the header 50, and a pressure hose 14 is attached to the outside.
A cap 5 having a pressure introduction pipe 52 connected to
3 is welded. Four piezo diffused resistors 54 to 5 are installed in the diaphragm part of the silicon pellet 51.
7 is installed. When the pressure inside the air trap 12 is introduced through the pressure introduction pipe 52, the diaphragm portion is deformed and the resistance values of the piezo diffusion resistors 54 to 57 change. By connecting the piezo diffused resistors 54 to 57 with a prism as shown in FIG. 8, changes in their resistance values are converted into voltage changes with good sensitivity and are outputted from output terminals 58 and 59. In FIG. 8, 60 is a constant current circuit that supplies a constant current of 1.5 [mA] to the bridge. In addition, in Fig. 7, 61 is an adhesive, 62 is an insulating material, 63 is a conductor, 64 is 6 lead terminals, and the 8th
This corresponds to point P in the figure.

Since the characteristics of the pressure sensor 49 also change depending on the ambient temperature as shown in FIG. 9, the above-mentioned control is necessary.

(G) Effects of the Invention In view of the fact that the output of the water level detection device in a washing machine changes depending on the surrounding temperature, the present invention provides a method for detecting water level when the output of the water level detection device becomes almost constant during water supply. Since the output characteristics change depending on the temperature, the water supply is stopped when the specified water level cannot be detected and the water supply has already reached the overflow level, so it is possible to perform a good water supply operation regardless of the ambient temperature. I can do it.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the water supply operation of the washing machine of the present invention, Fig. 2 is a cross-sectional view of the internal mechanism of the same main part, Fig. 3 is a sectional view of the water level sensor, Fig. 4 is an oscillation circuit diagram, and Fig. 5 is a sectional view of the water level sensor. The figure is a block circuit diagram of the control mechanism.
FIG. 6 is a characteristic diagram of the water level detection device, FIG. 7 is a cross-sectional view of the internal structure of the pressure sensor, FIG. 8 is a diagram of its output detection circuit, and FIG. 9 is a dynamic output characteristic diagram. 4... Dehydration/washing tub, 15... Water supply solenoid valve (water supply means), 17... Overflow port, 25... Water level detection device, 26... Microcomputer (control means).

Claims (1)

[Claims] 1. A washing tub having an overflow port at the top, a means for supplying water into the washing tub, and a water level detection device that sequentially outputs a signal corresponding to changes in the water level in the washing tub and whose output changes depending on the ambient temperature; and a control means for detecting an output corresponding to a specified water level from the water level detection device to control the operation of a load such as the water supply means, and when the control means supplies water to the washing tub,
A washing machine characterized in that, when the output of the water level detection device becomes approximately constant before detecting the output corresponding to a specified water level from the water level detection device, a command is given to stop water supply.