Thermostat is a kind of automatic temperature regulating device, usually containing a temperature sensing component, by expanding or shrinking to turn on and off the flow of the cooling liquid, that is, automatically adjust the water into the radiator according to the temperature of the cooling liquid, change the circulation range of the cooling liquid, to adjust the cooling system heat dissipation capacity.
The main engine thermostat is wax-type thermostat, which is controlled by the paraffin inside through the principle of thermal expansion and cold contraction to control the coolant circulation. When the cooling temperature is lower than the specified value, the refined paraffin in the thermostat temperature sensing body is solid, the thermostat valve under the action of the spring to close the channel between the engine and the radiator, the coolant through the water pump to return to the engine, the engine small cycle. When the temperature of the coolant reaches the specified value, the paraffin begins to melt and gradually becomes a liquid, and the volume increases and presses the rubber tube to make it shrink. At the same time, the rubber tube shrinks and exerts an upward thrust on the push rod. The push rod has a downward thrust on the valve to make the valve open. At this time, the coolant flows through the radiator and thermostat valve, and then flows back to the engine through the water pump for large circulation. Most of the thermostat is arranged in the water outlet pipe of the cylinder head, which has the advantage of simple structure and easy to discharge the bubbles in the cooling system; The disadvantage is that the thermostat often opens and closes when working, producing oscillation phenomenon.
When the engine operating temperature is low (below 70°C), the thermostat automatically closes the pathway leading to the radiator, and opens the pathway leading to the water pump. The cooling water flowing out of the water jacket enters the water pump directly through the hose, and is sent to the water jacket by the water pump for circulation. Because the cooling water does not dissipate by the radiator, the working temperature of the engine can be increased rapidly. When the working temperature of the engine is high (above 80°C), the thermostat automatically closes the path leading to the water pump, and opens the path leading to the radiator. The cooling water flowing out of the water jacket is cooled by the radiator and then sent to the water jacket by the water pump, which improves the cooling intensity and prevents the engine from overheating. This cycle route is called the large cycle. When the engine operating temperature is between 70 °C and 80°C, large and small cycles exist at the same time, that is, part of the cooling water for large cycle, and the other part of the cooling water for small cycle.
The function of the car thermostat is to close the car before the temperature has not reached the normal temperature. At this time, the cooling liquid of the engine is returned to the engine by the water pump, and the small circulation in the engine is carried out to make the engine warm up quickly. When the temperature exceeds the normal can be opened, so that the cooling liquid through the whole tank radiator loop for large circulation, so as to quickly heat dissipation.
