How does the thermostat work?

Olga Izvekova
Olga Izvekova
April 16, 2013
How does the thermostat work?

Automotive thermostat is a small but very important part of the car, which is responsible for maintaining the optimum engine temperature, and, therefore, accelerates the warm-up time in winter and prevents overheating in summer. The thermostat is installed in a liquid cooling system between the engine and the radiator.

The principle of operation of the thermostat is very simple. While the temperature of the engine is in the range of permissible temperatures, the thermostat is closed and this blocks the flow of cooling liquid into the radiator and the car engine. If the temperature of the motor becomes critical, the thermostat opens and the radiator begins to flow and cool it. The response temperature of the device can be different and is calculated by the car designers individually for each model. However, on average it is 95 ° C.

In all cars, this item has almost the same structure. It consists of a seamed case of brass, copper or plastic.Inside there is a ball of wax, to which are added impurities from powder of graphite, copper and aluminum. Wax was chosen as the working material since this material expands greatly when heated. Additives make expansion even more voluminous, and with their help the temperature of the start of expansion is regulated. While the temperature is not high, the wax is in a solid state. When the temperature becomes more than 80 ° C, it begins to melt and when it reaches 95 ° C it expands so much that it pushes the sleeve, which is trimmed from it by a rubber sleeve. The sleeve in turn opens the valve, which passes the cooling fluid to the engine. When the engine cools down, the wax will go back to a solid state, and the hub will return to its original position with the help of a spring.

The cooling system of the car consists of 2 circuits, called small and large. The thermostat regulates the work of only a large contra, without interfering with the work of a small one.

How the thermostat works can be checked independently by immersing the device in a container with warming water. At a temperature close to boiling, the thermostat will work and the stem will come out of it.

For some modern cars 2 types of thermostats are produced - summer and winter.

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