What is the function of an automotive thermostat?

[LeRiley]

The function of an automotive thermostat is to automatically regulate the amount of coolant entering the radiator based on the coolant temperature, thereby adjusting the cooling system's heat dissipation capacity to ensure the engine operates within an appropriate temperature range. When the coolant temperature is below the specified value, the refined paraffin wax inside the thermostat's temperature-sensing element remains in a solid state, and the thermostat valve closes the passage between the engine and the radiator under the action of a spring, causing the coolant to return to the engine via the water pump. When the coolant temperature reaches the specified value, the paraffin wax begins to melt and gradually turns into a liquid, expanding in volume and compressing the rubber tube to make it contract. As the rubber tube contracts, it exerts an upward thrust on the push rod, allowing the coolant to flow back to the engine via the radiator and thermostat valve, and then through the water pump.