Working principle of a temperature control switch on a car: A bimetal structure is embedded in the temperature control switch. Due to different thermal expansion coefficients of the metals, the contact will deform and engage when a critical temperature is reached, thus switching on the electric circuit. When the temperature drops below the threshold, the contact will resume its original position and the circuit will be switched off.
The water temperature control switch uses a high-grade dish-shape bimetal strip of a renowned foreign brand as the temperature sampling element. It is installed on a sensitive point of the radiator in order to collect water temperature change signals in the radiator dynamically. Since the dish bimetal strip is able to deform under high temperature and jump transiently, it can connect two contact points rapidly and start the fan to cool the water in the radiator. It therefore plays a protective role for the safety of the automotive engine. The working rage of the temperature control switch is 85~105℃.
It consists of a wax temperature-sensing driving element and a double-gear actuator mechanism. When heated, the wax changes from solid to liquid and expands rapidly, thus moving the push rod and controlling opening/closing of the contracts. With rising temperature of the liquid coolant, the wax starts to expand, drives the push rod through the rubber seal film, and presses down the tension spring frame. When the coolant temperature reaches 95℃, the low-speed contact point will close, and as a result the radiator motor fan will be powered on, starting to run at a low speed of 1600 r∕min.
When the coolant temperature reaches 105℃, the high-speed contact will close due to rapid expansion of the wax. This will cause the radiator motor fan to rotate at a high speed of 2400 r∕min for faster cooling. When the coolant temperature drops, the wax will shrink, and the push rod will retreat under the pull force of the contact, thus breaking the contact. In this way, the radiator motor fan is controlled.
Name: temperature control switch/3P, black
Borsehung No. : B13129
Ref No. : 1J0959481A
Applicable models:
Skoda: CIT12-/FAB00-10/OCT97-13/RAP12-/RO06-11
VW: BE99-10/BO99-05/CA04-/FO04-12/GO98-/JE06-/PHAE02-07/PO02-/TOU03-10/TOUA03-10/UP12-
Seat: ALT07-14/CO03-09/IB02-13/LE00-13/TO99-13
Audi: A1 11-/A3 97-13/ATT99-06
