There are many kinds of bimetallic disc temperature controller, which can be divided into three kinds according to the action mode of contact clutch: slow moving type, flashing type and snap action type.
The snap action type is a bimetal disc temperature controller and a new type of temperature controller, used in the field of industrial appliances, electric machines, household appliances, especially in recent years, the development of microwave oven, water dispenser, coffee pot, electric oven, electromagnetic cooker, dishwasher, electric iron, rice cooker and other small appliances are more commonly used.
Snap action bimetal thermostat temperature controller is divided into open type (common structure as shown in Figure 3) and sealed type. The sealed type bimetallic thermostat is divided into automatic reset type (structure as shown in Figure 4) and manual reset type (structure as shown in Figure 5). All kinds of snap action bimetal thermostat models collectively known as KSD, temperature is graded set value, can not be adjusted. The working principle of automatic reset type snap action thermostat is to make bimetallic disc into dish-shaped element, generate displacement energy accumulation when heated, once overcome resistance reverse jump, push the push rod to make contact quickly break, automatically disconnect the circuit; When the temperature drops, the bimetallic disc jumps back to the original state, so that the contact is closed, and the circuit is automatically switched on, so as to achieve the purpose of temperature control.
Automatic reset snap action thermostat as a variety of electric heating appliances overheating protection, usually with disposable thermal fuse (also known as overtemperature safety) in series use, snap action thermostat as a primary protection. When the electric heating element overtemperature or dry burning, snap action thermostat quickly action automatically off the circuit, when the temperature is reduced, the circuit will be automatically switched on. The thermal fuse automatically disconnects the circuit as a secondary protection when the thermal element overtemperature is caused by the failure or failure of the snap action thermostat, effectively preventing the burning out of the electric element and the resulting fire accident.
As can be seen from Figure 5, the snap action manual reset thermostat is equipped with a prototype spring and a manual reset mechanism. When the bimetallic disc is heated and deformed to a certain extent, the jump occurs, and the conical spring is pushed by the bimetallic disc and the reverse jump, and the contact is broken by the push rod and automatically breaks the circuit; When the temperature drops, the bimetallic disc is restored to its original state, but because the conical spring has no automatic reset ability, it can not rebound and reset, and the contact still does not move. It is necessary to press the manual reset button, with the help of external force to reset the embryonic spring disc, and then the contact is closed.
Therefore, the water dispenser products developed in recent years all use the snap action type automatic reset thermostat and manual reset thermostat in tandem, the former is used for temperature control, the latter is used for overheating protection. When the water dispenser overtemperature or dry burning, manual reset thermostat action protection, permanent disconnect circuit. Only when the fault is removed, press the reset button to connect the circuit, to make the water dispenser resume normal work. In addition, high-grade boiling type electric water bottle, electric water heater is often used to manually reset the temperature controller, so that the electric water bottle, electric water heater has the function of connecting the power to make the water boil again in the state of insulation.
Post time: Jan-16-2023