What is the temperature sensor of the electric kettle? What is the general working principle?

◆ The temperature sensor of electric kettle is a bimetallic heat sensitive device. Bend in one direction when the temperature is low, and bend in the other direction when the temperature reaches the specified value, disconnect the circuit and stop heating. This sensor is skillfully used in the electric kettle.

1. Working process of heating circuit of electric kettle

The AC 220V power supply supplies power to the electric kettle. The L (live wire) terminal of the AC power supply is connected to the boiling water heater EM and one end of the insulated heater EH2 through the thermal fuse FU, and the N (neutral wire) terminal of the AC power supply is connected to the other end of the insulated heater EH2 through the thermostat ST, while the N (neutral wire) terminal of the AC power supply is connected to the other end of the insulated heater EH2 through the diode VIE℃ and the selector switch SA. Make both ends of the boiling water heater and the insulation heater have AC voltage, and start heating, as shown in the figure.

2. Working process of heating control circuit

When the electric kettle starts to boil water, the thermostat ST is in a low temperature state. At this time, there is conduction between the two lead terminals of the thermostat ST, which provides a path for power supply. At this time, the green indicator light is on, the red indicator light is off, and there is no voltage at both ends. When the temperature in the water bottle exceeds 96℃ (the water is boiling), the thermostat ST will automatically close and stop supplying power to the water heater. At this time, there is still 220V AC voltage at both ends of the insulation heater, but the energy generated by the large resistance of the insulation heater is only 1/20 of that of the boiling water heater, so it only plays the role of insulation. At this time, AC 220V supplies power to the red indicator through EM, and the green indicator goes out and the red indicator lights up.

If the water temperature in the electric thermos drops, the thermostat ST will automatically turn on again and continue to add the boiling water heater to keep the boiling water in the thermos above 90℃.

3. Working process of electromagnetic pump circuit

When drinking water, the socket selector switch SA is operated, so that the AC power supply supplies power to the bridge rectifier circuit VD 1 ~ VD4 through the insulated heater and rectifier diode VD0, and the rectified voltage becomes DC voltage, which is smoothed by the capacitor C 1. The filtered DC voltage is changed into a stable voltage of 12V through the voltage stabilizing circuit, which is added to the electromagnetic pump motor to start the power pump to work, and hot water automatically flows out.