How does the fan behind the car radiator work?
There are three types of cooling devices for internal combustion engines, water cooling, oil cooling, and air cooling. The automobile engine cooling device is mainly water-cooled. It uses the circulating water in the cylinder water channel to cool and introduces the heated water in the water channel into the radiator (water tank), and then returns to the water channel after being cooled by the wind.
To ensure the cooling effect, the automobile cooling system generally consists of a radiator (1), a thermostat (2), a water pump (3), a cylinder water channel (4), a cylinder head water channel (5), and a fan. Take a car as an example. The radiator is responsible for the cooling of circulating water. Its water pipes and heat sinks are mostly made of aluminum. The aluminum water pipes are made of flat shape, and the heat sink is corrugated. Pay attention to the heat dissipation performance. The installation direction is perpendicular to the airflow. Direction, try to make the wind resistance as small as possible, and the cooling efficiency should be high.
The radiator's cooling water is not pure water but a mixture of water (in line with drinking water quality), antifreeze (usually ethylene glycol), and various special-purpose preservatives coolant. The antifreeze content in these coolants accounts for 30% to 50%, which increases the boiling point of the liquid. Under a specific working pressure, the car coolant's allowable working temperature can reach 120 degrees Celsius, which exceeds the boiling point of water and is not easy to evaporate.
The circulation of the coolant realizes the engine. The component that forces the coolant's circulation is the water pump, which is driven by the crankshaft belt, and the water pump impeller pushes the coolant to circulate in the entire system. The cooling of the engine by these coolants must be adjusted according to the machine's working conditions. When the engine temperature is low, the coolant will circulate in the engine. When the engine temperature is high, the coolant will circulate between the engine and the radiator. The control component that realizes the different circulation of the coolant is the thermostat. The thermostat is a valve. Its principle is to use materials to expand and contract with temperatures, such as paraffin or ether. When the water temperature is high, the material expands to open the valve, and the coolant performs a large cycle. When low, the fabric shrinks and closes the valve, and the coolant circulates in a small amount.
To improve the radiator's cooling capacity, a fan is installed behind the radiator for forced ventilation. The crankshaft belt directly drove the previous car radiator fan. When the engine started, it would turn, and it could not change according to the change of engine temperature. To adjust the radiator's cooling power, movable shutters should be installed on the radiator to control the wind power. Modern cars have commonly used fan electromagnetic clutches or electronic fans. When the water temperature is relatively low, the clutch is separated from the rotating shaft, and the fan does not move. When the water temperature is relatively high, the temperature sensor is powered on to engage the clutch with the rotating shaft, and the fan rotates. Similarly, the electronic fan is directly driven by the motor, and the temperature sensor controls the engine. Temperature sensors control the operation of these two types of radiator fans.
The radiator doubles as water storage and heat dissipation. If you rely solely on the radiator, there are three disadvantages. One is that the water pump's suction side is prone to boiling due to low pressure, and the impeller is prone to cavitation; The high-temperature coolant is easy to boil and escape. Therefore, the designer installed an expansion tank. Its upper and lower water pipes were connected to the upper part of the radiator and the water pump's inlet to prevent the above problems.
The cooling system of a car is now more complicated than in the past, mainly because of temperature control elements. The radiator fan can be 'according to changes in the engine temperature' , and the cooling system generally uses coolant. Of course, the engine's heat is also the energy produced by the fuel, and cooling it is a waste of last resort. Therefore, people are studying an insulated machine made of ceramic material that does not require cooling. Once it is realized in the future, the engine will be small and straightforward.