JPH0536070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pressure-type water level detection device for automatic electric washing machines used in general households.

Conventional configuration and problems thereof Conventionally, in this type of detection device, a pressure sensor 3 is connected to an air trap 2 provided at the bottom of a washing machine 1 by an air hose 4, as shown in FIG. A water level determining device 5 is provided for determining the water level based on an electrical signal from the pressure sensor 3. A change in the water level in the washing machine 1 is detected by a pressure sensor 3 as a change in the pressure of the air in the air trap 2, which is converted into an electrical signal, and the water level is detected by a water level determining device 5. 6 is a drive unit including a motor, a speed reduction mechanism, etc., 7 is a stirring blade, and 8 is a motor control device. 18 is a water supply valve, and 19 is a drain valve. In automatic electric washing machines, the water level detection device is used to display the water level, finish water supply/drainage, and check the water level to prevent water volume from decreasing due to water leakage during washing or rinsing. However, during cleaning and rinsing, the water level fluctuates significantly due to the water flow generated by the motor, and the Air Trap 2
This also caused the internal pressure to change, causing the problem that water level detection results equivalent to the actual amount of water could not be obtained. Therefore, when constantly detecting the water level using a conventional pressure-type water level detection device, during washing and rinsing, it is necessary to take into account the fluctuation range of the water level caused by the motor drive, and to prevent the amount of water from leaking. The detection point for a drop in water level due to a decrease in water level can only be set at a level lower than the above fluctuation range, and if the water volume actually decreases, the fabric of the washing machine may become stained.
It is insufficient. In addition, even when the water level is displayed according to the detection results of the water level detection device, if the water level is constantly detected during washing and rinsing, the level of the water level display will change each time the water level changes due to motor drive. It becomes very difficult to see.

OBJECTS OF THE INVENTION The present invention solves these conventional problems and provides a water level detection device that can bring the detection result of water level during washing and rinsing closer to a level equivalent to the actual amount of water.

Structure of the Invention The water level detection device of the present invention includes an air trap provided at the bottom of the washing tub, an air hose that guides air from the air trap, a pressure sensor connected to the air hose, and a water level determination that determines the water level based on an electric signal from the pressure sensor. and a water level judgment timing determining device that detects when the motor reversal control is stopped based on a signal from a motor control device that controls the drive of the motor and outputs the detected signal to the water level determining device. , the water level determination device inputs the signal from the pressure sensor when the motor is stopped, and can determine the water level, so that even during cleaning or rinsing,
The water level can be detected when the motor is stopped and the motor changes its rotational direction from side to side, and there is little vertical fluctuation in the water level caused by the water flow, and the actual water level can be detected better.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 to 4 of the accompanying drawings. Note that the same parts as in FIG. 1 are given the same reference numerals and detailed explanations are omitted. 9 is a water level judgment timing determining device. The water level determination device 5 includes a microcomputer 10 and an A/D
It is composed of a converter 11. The motor control device 8 includes a microcomputer 10, transistors 12 and 13, and bidirectional three-terminal rectifying elements (hereinafter referred to as triacs) 15 and 16.

The water level judgment timing determining device 9 is composed of a microcomputer 10. It is also assumed that the output from the water level determination device 5 is to drive the water supply valve 18 by firing the transistor 14 and triax 17. The electrical signal from the pressure sensor 4 is converted into digital data by the A/D converter 11, and is inputted to the microcomputer from the input terminal A as water level data. The left and right rotation of the motor 21 is switched by alternately firing the triacs 15 and 16 by switching the voltage levels of the output terminals B and C of the microcomputer 10 and switching the transistors 12 and 13. motor 2
1 is stopped by setting both output terminals B and C to a low level, turning off transistors 12 and 13, extinguishing triacs 15 and 16, and cutting off power to motor 21.

FIG. 4 is a flowchart of a water level determination program for water leak detection by the microcomputer 10.

In step 1, it is determined whether or not to perform water level determination for water leak detection, and if not, the program moves to the next program. If you decide to do so, go to step 2. In step 2, it is determined whether the motor is stopped or not. If the motor is running, highly accurate water level detection is not possible, so the program moves on to the next program. If the motor is stopped, go to step 3 and turn on the A/D converter 11.
Input the water level data from and determine the current water level.
Based on the water level determination result, it is determined in step 4 whether the current water level is lower than the previous water level. If it is determined in step 4 that the water level has decreased due to a water leak, etc., the program proceeds to step 5, where an output is issued to open the water supply valve 18 to supply water, and if not, the program proceeds to the next program.

As described above, since the water level determination is performed while the motor is stopped, the water level can be detected without being significantly affected by vertical movement caused by motor drive.

Although the above embodiment is constructed using a microcomputer, the present invention is not particularly limited to this, and the point is that water level determination may always be performed while the motor is stopped.

Effects of the Invention As is clear from the above embodiments, the water level detection device of the present invention particularly has a water level determination timing determining device, and by determining the water level while the motor is stopped, the water level can be changed even during cleaning or rinsing by driving the motor. This allows for more accurate water level detection.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional water level detection device, FIG. 2 is a block diagram showing the configuration of a water level detection device according to an embodiment of the present invention, FIG. 3 is an electric circuit diagram thereof, and FIG. It is a flowchart showing an example of a program when determining a water level. 1... Washing tub, 2... Air trap, 3... Air hose, 4... Pressure sensor, 5... Water level determination device, 8... Motor control device, 9... Water level determination timing determining device.

Claims (1)

[Claims] 1 An air trap installed at the bottom of the washing tub, an air hose that guides air from the air trap, a pressure sensor connected to the air hose, a water level determination device that determines the water level based on the electrical signal from the pressure sensor, and a motor that controls the drive of the motor. The water level determination device includes a control device and a water level determination timing determining device that detects when the motor is stopped based on a signal from the motor control device and outputs it to the water level determining device, and the water level determining device detects when the reverse control is stopped during washing or rinsing. A water level detection device for an electric washing machine, characterized in that the water level detection device determines the water level judgment timing.