In recent years, the sensor and its technology are more and more widely used in washing machines. The sensor detects the washing machine status information such as water temperature, cloth quality, cloth amount, and cleaning degree, and sends this information to the microcontroller. The microcontroller applies the fuzzy control program to analyze the detected information. To determine the best washing time, water flow intensity, rinsing mode, dehydration time and water level, the whole process of washing machine is automatically controlled.
Here are the main sensors in a fully automatic washing machine.
Cloth quantity sensor
Cloth load sensor, also known as clothing load sensor, it is used to detect the amount of clothing when washing. According to the sensor detection principle can be divided into three types:
1. According to the change of motor load current to detect the weight of clothing. The detection principle is that when the load is large, the current of the motor becomes larger; When the load is small, the motor current becomes smaller. Through the determination of the change of the motor current, the weight of the clothing is judged according to the integral value of a certain time.
2. According to the change law of the electromotive force generated at both ends of the winding when the motor is stopped, it is detected. The detection principle is that when a certain amount of water is injected into the washing bucket, the clothes are put into the bucket, then the driving motor works in the way of intermittent power operation for about one minute, using the induction electromotive force generated on the motor winding, by photoelectric isolation and comparison of the integral type, the pulse signal is generated, and the number of pulses is proportional to the Angle of the inertia of the motor. If there are more clothes, the resistance of the motor is large, the Angle of inertia of the motor is small, and accordingly, the pulse generated by the sensor is small, so that the amount of clothing is indirectly “measured”.
3. According to the pulse drive motor “turn”, “stop” when the inertia speed pulse number measurement of clothing. Put a certain amount of clothes and water in the washing bucket, and then pulse to drive the motor, according to the “on” 0.3s, “stop” 0.7s rule, repeated operation within 32s, during the motor in the “stop” when the inertia speed, measured by the coupler in a pulse way. The amount of washing clothes is large, the number of pulses is small, and the number of pulses is large.
Cloth Sensor
The cloth sensor is also called the cloth testing sensor, which is designed to detect the texture of clothing. Application Clothing load sensors and water level transducers can also be used as fabric sensors. According to the proportion of cotton fiber and chemical fiber in the clothing fiber, the fabric of the clothing is divided into “soft cotton”, “harder cotton”, “cotton and chemical fiber” and “chemical fiber” four files.
The quality sensor and the quantity sensor are actually the same device, but the detection methods are different. When the water level in the washing bucket is lower than the set water level, and then still according to the method of measuring the amount of clothing, let the drive motor work for a period of time in the way of power off, and detect the number of pulses emitted by the amount of clothing sensor during each power off. By subtracting the number of pulses from the number of pulses obtained when measuring the quantity of clothing, the difference between the two can be used to determine the quality of clothing. If the proportion of cotton fibers in the clothing is large, the pulse number difference is large and the pulse number difference is small.
Water level sensor
The electronic water level sensor controlled by single chip microcomputer can control the water level automatically and accurately. The water level in the washing bucket is different, and the pressure on the bottom and wall of the bucket is different. This pressure is transformed into the deformation of the rubber diaphragm, so that the magnetic core fixed on the diaphragm is displaced, and then the inductance of the inductor is changed, and the oscillation frequency of the LC oscillation circuit is also changed. For different water levels, the LC oscillation circuit has a corresponding frequency pulse signal output, the signal is input to the microcontroller interface, when the water level sensor output pulse signal and the selected frequency stored in the microcontroller at the same time, the microcontroller can determine that the required water level has been reached, stop water injection.
Appropriate laundry temperature is conducive to the activation of stains, can improve the washing effect. The water temperature sensor is installed in the lower part of the washing bucket, and the NTC Thermistor is used as the detection element. The temperature measured when turning on the washing machine switch is the ambient temperature, and the temperature at the end of water injection is the water temperature. The measured temperature signal is input to the MCU to provide information for fuzzy inference.
Photosensor
The photosensitive sensor is the cleanliness sensor. It is composed of light-emitting diodes and phototransistors. The light-emitting diode and phototransistor are set face to face at the top of the drain, its function is to detect the light transmission of the drain, and then the test results are processed by a microcomputer. Determine washing, drainage, rinsing and dehydration conditions.
Post time: Jun-16-2023