The main components of engine cooling system

[袁春凤 (Tiffany)]

thermostat

1) Function: Change the circulation route and flow rate of cooling water, automatically adjust the cooling intensity, so that the temperature of cooling water is often maintained at 80 to 90 degrees

2) the installation position is installed in the passage of cooling water circulation, usually installed in the outlet of the cylinder head.

3) form: divided into wax type and foldable type. 

The wax thermostat is equipped with paraffin wax in the space between the rubber tube and the inductor. In order to improve the thermal conductivity, paraffin wax is often mixed with copper or aluminum powder. At normal temperature, paraffin wax is present and the valve is pressed on the valve seat. At this point the valve closes the water path to the radiator, cooling water from the engine cylinder head outlet, through the pump flow back to the cylinder block water jacket for small circulation. When the water temperature of the engine rises, the paraffin wax becomes liquid gradually, and the volume increases accordingly, forcing the rubber tube to shrink, thus producing upward thrust on the upper end of the thrust rod. The upper end of the reversing rod is fixed, so the reversing rod produces a downward reverse thrust on the rubber pipe and the inductor, and the valve opens. When the water temperature of the engine reaches above 80, the valve opens completely, and the cooling water from the outlet of the cylinder head flows to the radiator for large circulation.

FAW Audi 100 cars and CA1091 trucks are all made of wax type thermostat.

The folding thermostat is made of an elastic, folding, airtight cylinder (made of brass) with a volatile ether inside. The main valve and side valve move up and down with the upper end of the expansion cylinder. The vapor pressure of the liquid in the expansion cylinder varies with the ambient temperature, so the height of the cylinder varies with the temperature. When the engine works under normal thermal condition, that is, the water temperature is higher than 80 C, the cooling water should all flow through the radiator, forming a large cycle. At this point the main valve of the thermostat is fully opened, while the side valve closes the bypass hole completely: when the cooling water temperature is lower than 70 degrees Celsius, the steam pressure in the expansion cylinder is very small, so that the cylinder shrinks to the minimum height. The main valve is pressed on the valve seat, that is, the main valve is closed and the side valve is opened. At this time, the water path from the water jacket to the radiator is cut off. The water in the water jacket can only flow out of the by-pass hole into the pump through the by-pass pipe, and then is pressed into the engine water jacket by the pump. At this time, the cooling water does not flow through the radiator, but follows the water jacket and the pump. Ring, so as to prevent the engine from overcooling, and make the engine hot quickly and evenly: when the engine cooling water temperature in the range of 70-80, the main valve and side valve in the semi-open and closed state, at this time part of the water for large circulation, while the other part of the water for small circulation.Thanks for the help of the Chongqing Feilong Jiangli Auto Parts’ Technical dept.

1) When the cooling water temperature is lower than 76 degrees, the main valve of the thermostat is closed, and the sub-valve opens the cooling water to circulate in a small range between the pump and the water jacket, so that the water temperature rises rapidly. When the water temperature is higher than 86 degrees, the main valve of the thermostat is fully open, the secondary valve is fully closed, and the cooling water flows through the radiator for water circulation to keep the engine at normal working temperature.