Turbocharger structure principle: Exhaust gas turbocharger is mainly composed of pump wheels and turbines, of course, there are some other control elements. The pump wheel and the turbine are connected by an axle, that is, the rotor, the exhaust gas of the engine drive the pump wheel, the pump wheel drives the turbine to rotate, and the turbine rotates to pressurize the intake system. The supercharger is mounted on the exhaust side of the engine, so the supercharger working temperature is very high, and turbocharger at work when the rotor speed is very high, can reach a hundred thousand of RPM, so high speed and temperature so that common mechanical needle roller or ball bearings can not work for the rotor, the turbocharger is generally used fully floating bearings, It is lubricated by oil, and coolant is cooled for supercharger. In the past, turbochargers were mostly used on diesel engines, because the combustion of petrol and diesel was different, so there was a difference in the way the engine used turbochargers.
Petrol engines are different from diesel engines, and it is not air that enters the cylinders, but gasoline and air mixtures, which can be easily deflagration. Therefore, the installation of turbocharger must avoid deflagration, which involves two related issues, one is high temperature control, the other is ignition time control.
After mandatory pressurization, the temperature and pressure will increase when the gasoline engine is compressed and burned, and the deflagration tendency increases. In addition, the gasoline engine exhaust temperature is higher than the diesel engine, and it is not appropriate to increase the valve overlap angle (the timing of inlet and outlet opening at the same time) to enhance the cooling of the exhaust, reducing the compression ratio will cause inadequate combustion. Also, the engine speed is higher than the diesel engine, the air flow changes greatly, it is easy to cause the turbocharger reaction lag. In response to a series of problems in the use of turbocharger, the engineer has made an improvement to the gasoline engine.