Automatic heat preservation rice cooker circuit

What is popular now is the double-layer automatic heat preservation rice cooker, the circuit of which
is shown in Figure 1-21. It consists of a pot cover, an inner pot, an outer pot, an electric heating plate and a control element.
The electric heating plate is made by casting a metal tubular electric heating element in an aluminum alloy body and then processing it
. The plate surface is made into a emblem-shaped convex shape, which fits the bottom of the inner pot, and
a magnetic steel rolling temperature switch is installed in the center .
    The control components of the double-layer automatic heat preservation rice cooker mainly rely on the magnetic steel temperature limit
switch and the bimetal heat preservation switch. The circuit is shown in Figure 1-21. SB2 is
a bimetal heat preservation switch, the temperature is adjusted between 45--65℃, and the contact is normally closed. SB1 is
a contact switch of a magnetic steel temperature limit switch. Its operating Curie temperature is (103±2)°C and
cannot be automatically reset. When cooking, press switch SBI. The circuit is energized and cooking begins
. When the temperature rises to (65±5)℃, the bimetallic piece acts, but because
the contact switch SB1 of the magnetic steel temperature limit switch is still connected, the circuit is energized. When the rice is cooked, the water in the pot is sucked dry, and the temperature rises above 100°C.
When it reaches (103±2)°C, the soft magnetic steel loses magnetism. When the switch SB1 is opened under the action of the gravity of the permanent magnet and the force of the spring , the heating plate stops heating. Since
SB1 cannot automatically reset, the circuit is not energized. When the temperature drops below (65±5)℃, the bimetallic piece will automatically close. When the temperature exceeds
(65±5)℃, it will open. By switching on and off alternately in this way, it plays the dual roles of cooking rice and keeping it warm. The indicator light is used to indicate that the heating plate is in working
condition.
    The timed automatic heat preservation rice cooker is based on the automatic heat preservation rice cooker and is equipped with a 6h, 12h or 24h timer, so that it can automatically start the rice cooker and start cooking
according to the time scheduled by people . It not only saves electricity, but also allows you to get fresh rice on time.