Rice cooker circuit principle

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

inductance

SMD aluminum electrolytic capacitor

The rice cooker is mainly composed of a heating plate, a temperature limiter, a heat preservation switch, a lever switch, a current limiting resistor, an indicator light, a socket, and the like.
1. Heating plate: This is an aluminum alloy disc with embedded electric heating tube. The inner pot is placed on the heating plate. You can see it by removing the inner pot. This is the main heating element of the rice cooker.
2. Temperature limiter: Also called magnetic steel, it is equipped with a permanent magnetic ring inside, with a spring on it, which can be pressed and placed in the center of the heating plate. When cooking, hold the bottom of the inner pot by the suction of the permanent magnetic ring. When cooking rice, the temperature of the bottom of the pot is continuously increased, and the suction force of the permanent magnetic ring is weakened with the increase of temperature. When the water in the inner pot is evaporated, the temperature of the bottom of the pot reaches 103±2 ° C, the magnetic ring The suction force is less than the spring force on the spring, the temperature limiter is pulled down by the spring, the lever switch is pressed, and a passage between the power source and the heat pipe is cut off.
3, insulation switch: also known as thermostat. It consists of an energy storage spring piece, a pair of normally closed contacts (one end of the contact is connected to the other end of the power supply and a heat pipe), a pair of normally open contacts (one end of the contact is connected to the other end of the power supply and the heat preservation indicator), Bimetal composition. At the time of cooking, the temperature inside the pot rises, and the two pieces of metal constituting the bimetal are different in heat expansion and contraction, and as a result, the bimetal is bent upward. When the temperature reaches above 80 °C, the upwardly bent bimetal can push open the normally open contact of the heat preservation switch, thereby cutting off a passage between the heat pipe and the power source; when the temperature in the pot drops below 80 ° C, the bimetal gradually Cooling, the degree of curvature is reduced, and gradually returns to the original position, and the normally closed contact is closed under the action of elasticity, so that the heating tube is energized and heated to realize the heat preservation function of the rice cooker.
4. Lever switch: The switch is completely mechanical. There are two pairs of normally open contacts, one of which is connected between the power supply and the heat pipe; the other is connected between the power supply and the heat preservation indicator. When cooking, press this switch to turn on the power to the heating tube. When the rice is good, the temperature limiter will bounce off and press the lever switch to make the switch bounce, so that the heating tube is only controlled by the heat preservation switch.
5, current limiting resistor: the appearance of black, like 2W carbon film resistor, connected between the heating tube and the power supply, plays a role in protecting the heating tube. The temperature limiter will automatically disconnect only when the water in the inner pot is completely dried. Therefore, if the rice cooker cooks more water, the heat pipe will work for a long time, which will easily cause overcurrent. At this time, the current limiting resistor will be blown first. Thereby protecting the heat pipe. The current limiting resistor is a key component to protect the heating tube and cannot be replaced by a wire.