Electric iron automatic temperature adjustment principle circuit diagram

How does the electric iron adjust the temperature? The credit also goes to the automatic switch made of bimetallic sheets.

Bimetallic sheets are made of copper and iron sheets of the same length and width that are tightly riveted together. When heated, because the copper sheet expands more than the iron sheet, the bimetallic sheet bends toward the iron sheet. The higher the temperature, the more pronounced the bending.

The picture on the right is a schematic structural diagram of an electric iron. At normal temperature, the contact point at the end of the bimetal piece is in contact with the contact point on the elastic copper piece. When the electric iron head is connected to the power supply, the current flows through the contacting copper sheets and bimetal sheets, and flows through the heating wire. The heating wire generates heat and transfers the heat to the metal soleplate at the bottom of the iron. People can use the heated soleplate to iron. Ironing clothes. As the power-on time increases, when the temperature of the base plate rises to the set temperature, the bimetal piece fixed to the base plate bends downward after being heated, and the contact point at the top of the bimetal piece separates from the contact point on the elastic copper piece, so The circuit is broken. At this time, the temperature of the base plate no longer rises, but decreases due to the heat dissipation of the base plate; the deformation of the bimetal piece also gradually recovers. When the temperature drops to a certain value, the bimetal piece and the elastic copper piece come into contact again, and the circuit is connected again , the temperature of the bottom plate begins to rise again. In this way, when the temperature is higher than the required temperature, the circuit is disconnected, and when the temperature is lower than the required temperature, the circuit is connected, thereby maintaining the temperature within a certain range.

So, how to make the electric iron have different temperatures? When you adjust the temperature knob upward, the upper and lower contacts move upward. The bimetal strip only needs to be bent slightly to separate the contacts. Obviously, the base plate temperature is lower at this time, and the bimetallic sheet can control the constant temperature of the base plate at a lower temperature. When you turn the thermostat down, the upper and lower contacts move downward, and the bimetal must bend downward to a large extent in order to separate the contacts. Obviously, the temperature of the bottom plate is higher at this time, and the bimetallic sheet can control the constant temperature of the bottom plate at a higher temperature. In this way, it can adapt to the different temperature requirements of the fabric.