The structure of ordinary rice cooker: ordinary rice cooker is mainly composed of heating plate, temperature limiter, heat preservation switch, lever switch, current limiting resistor, indicator light, socket, etc.
1. Heating plate: This is the main heating element of the rice cooker. This is an aluminum alloy disc with an electric heating tube embedded in it, and the inner pot is placed on it, and you can see it when you remove the inner pot.
2. Temperature limiter: also known as magnet. It is fitted with a permanent magnetic ring and a spring that can be pressed and positioned in the center of the heating plate. When cooking, when pressing the cooking switch, the suction of the magnet drives the lever switch to keep the power contact on, when cooking rice, the temperature of the bottom of the pot continues to rise, the suction of the permanent magnetic ring weakens with the increase of temperature, when the water in the inner pot is evaporated, the temperature of the bottom of the pot reaches 103±2C, the suction of the magnetic ring is less than the spring on it, the temperature limiter is pushed down by the spring, drive the lever switch, cut off the power supply.
3. Insulation switch: also known as thermostat. It is composed of a spring plate, a pair of normally closed contacts, a pair of normally open contacts, and a bimetal. When cooking, the temperature inside the pot rises, and the bimetal sheet bends upwards due to the different thermal expansion and contraction of the two metal sheets that make up the bimetal. When the temperature reaches above 80C, under the push of the upwardly curved bimetal sheet, the spring plate drives the normally open and normally closed contacts to convert, thereby cutting off the power supply of the heating tube and stopping heating. When the temperature in the pot drops below 80C, the bimetal sheet gradually cools and recovers, the normally open and normally closed contacts are converted again, and the power supply of the heating tube is connected to heat up. This repeats to achieve the heat preservation effect.
4. Lever switch: The switch is completely mechanical structure and has a normally open contact. When cooking, press this switch to connect the power to the heating pipe, and at the same time power the heating indicator to make it light. When the meal is ready, the thermolimiter pops down, drives the lever switch, and disconnects the contacts. After that, the heating tube is only controlled by the insulation switch.
5. Current limiting resistance: the appearance is golden yellow or white, the size is like 3W resistance, pressed between the heating tube and the power supply, playing the role of protecting the heating tube. The commonly used current limiting resistor is 185C 5A or 10A (depending on the rice cooker power). The current limiting resistor is a key component to protect the heating tube and can be replaced by wires.
Let me tell you a simple process:
A rice cooker uses a heating plate to cook rice at the bottom of an aluminum cooker. The heating plate contains an electric hot wire, which is controlled by an automatic switch.
There is a round hole in the center of the heating plate, and there is a warm and soft magnetic feeling in the hole, which is pressed against the bottom of the pot by means of a spring. This is a pure ferrite. It can be attracted by permanent magnets at 100°C or below. However, when it rises to 103 °C, it loses its magnetism and is no longer attracted to permanent magnets.
When the switch button is pressed, the switch crossbar presses the magnet upwards against the thermosensitive soft magnet. At this time, the hot wire is switched on and the heating begins.
When the rice in the pot boils, the water in the pot gradually decreases. When the water begins to dry, the temperature in the pot rises from 100°C. When it rises to 103 °C, the temperature sensing soft magnet is not attracted by the magnet, and the lever of the switch drops due to the elasticity of the spring and its own gravity, and the pressure separates the contact points, and the hot wire is powered off. At the same time, turn on another insulation circuit and keep the temperature of the rice at about 70°C
