Bimetallic thermostat is a protective device commonly used in household appliances. It is often used in the project. It can be said that the cost of this device is not high and the structure is very simple, but it plays a very big role in the product.
Different from other electrical appliances to complete the function, the biggest application of the thermostat is as a protective device, only when the machine is abnormal, the thermostat will work, and when the machine is working normally, the thermostat will not take effect.
The normally closed resettable temperature controller is used as an example. The main structure of the temperature controller is as follows: the temperature controller shell, aluminum cover plate, bimetal plate, and wiring terminal.
Bimetallic sheet is the soul component of the bimetal thermostat, bimetallic sheet is made of two pieces of metal with different thermal expansion coefficients pressed together, when the heat energy of the metal sheet increases, because the two pieces of metal thermal expansion and cold contraction degree is inconsistent, the tension of a piece of metal will slowly increase, the tension is greater than the elastic force of another piece of metal sheet, instantaneous deformation will occur, so that the contact of the metal sheet and the terminal contact separated. Disconnect the circuit. When the temperature decreases gradually, the shrinkage force of a piece of metal increases gradually. When the force is greater than another piece of metal, it will also cause deformation, which instantly makes the metal contact and the terminal contact connected, so as to make the circuit open.
Typically, on household appliances, resettable thermostats are paired with manual reset thermostats. For example, the heating tube on the washing machine and oven, because the temperature around the heating tube is very high, the use of conventional temperature sensor is a lot of cost increase, in addition to increase the computer board hardware cost and software design complexity, so the resettable temperature controller with manual bimetal thermostat becomes a cost and function optimal choice.
Once the resettable thermostat fails, the manual thermostat can be used as a double protection device. In most product designs, the manual thermostat will only act when the resettable thermostat fails. Therefore, once the manual thermostat needs to be reset, the user can be reminded to check whether the device works abnormally.
According to the above structure to expand, due to the different expansion coefficient of bimetallic sheet, thermal energy into mechanical energy, if replaced by temperature sensitive liquid, temperature generated pressure change, thermistor and other change sources, you can derive different temperature controller.
Post time: May-04-2023