The cooling system of automobile engine is forced circulation water cooling system, that is, the water pump is used to increase the pressure of coolant and force the coolant to circulate in the engine. The cooling system is mainly composed of water pump, radiator, cooling fan, compensation water tank, thermostat, water jacket in engine body and cylinder head and auxiliary devices.
The structure for the car's cooling system.
In the whole cooling system, the cooling medium is coolant, and the main parts include thermostat, water pump, water pump belt, radiator, cooling fan, water temperature sensor, liquid storage tank and heating device (similar to radiator).1. Coolant
Coolant, also known as antifreeze, is a liquid composed of antifreeze additives, additives to prevent metal corrosion and water. It needs anti freezing, anti-corrosion, thermal conductivity and non deterioration properties. Ethylene glycol is often used as the main component, plus anti-corrosion and water antifreeze.
2.Thermostat
When introducing the cooling cycle, it can be seen that the thermostat decides whether to go through "cold cycle" or "normal cycle". The thermostat opens after 80 ℃, and the opening is the maximum at 95 ℃. If the thermostat cannot be closed, the cycle will enter the "normal cycle" from the beginning, resulting in that the engine cannot reach or cannot reach the normal temperature as soon as possible. The thermostat cannot be opened or opened flexibly, which will make the coolant unable to circulate through the radiator, resulting in excessive temperature or normal when it is high. If the thermostat cannot be opened, resulting in overheating, the temperature and pressure of the upper and lower water pipes of the radiator will be different.3. Water pump
The function of the water pump is to pressurize the coolant and ensure its circulation in the cooling system. The failure of the water pump is usually caused by the damage of the water seal, resulting in liquid leakage, abnormal rotation or sound due to leak problems. In case of engine overheating, the first thing to pay attention to is the water pump belt, and check whether the belt is broken or loose.
4. Radiator
When the engine is working, the coolant flows in the radiator core, and the air passes outside the radiator core. The hot coolant becomes cold due to heat dissipation to the air. Another important small part on the radiator is the radiator cap, which is easy to be ignored. As the temperature changes, the coolant will "expand with heat and contract with cold", and the internal pressure of the radiator increases due to the expansion of the coolant. When the internal pressure reaches a certain value, the radiator cap will open and the coolant will flow to the accumulator; When the temperature decreases, the coolant flows back into the radiator. If the coolant in the reservoir does not decrease, but the radiator level decreases, the radiator cap will not work!5.Cooling fan
During normal driving, the high-speed air flow is enough to dissipate heat, and the fan generally does not work at this time; However, when running at slow speed and in place, the fan may rotate to help the radiator dissipate heat. The start of the fan is controlled by the water temperature sensor.
6.Water temperature sensor
The water temperature sensor is actually a temperature switch. When the inlet water temperature of the engine exceeds 90 ℃, the water temperature sensor will connect the fan circuit. If the circulation is normal and the fan does not rotate when the temperature rises, the water temperature sensor and the fan itself need to be checked.
7.Accumulator:
The function of the liquid storage tank is to supplement coolant and buffer the change of "thermal expansion and cold contraction", so do not overfill. If the liquid storage tank is completely empty, you can't just add liquid to the tank. You need to open the radiator cap to check the liquid level and add coolant, otherwise the liquid storage tank will lose its function.
8.Heating device:
The heating device is in the car. Generally, there is no problem. It can be seen from the introduction of the cycle that this cycle is not controlled by the thermostat, so turn on the heating when the car is cold. This cycle will have a slightly delayed impact on the temperature rise of the engine, but the impact is really small. There is no need to freeze people in order to raise the temperature of the engine. It is also because of the characteristics of this cycle that in the emergency of overheating of the engine, opening the window and turning the heating up to the maximum will help to cool the engine.
