Turbocharger is mainly composed of pump wheel and turbine, and of course there are other control components. Pump wheel and turbine are connected by shaft, that is, rotor. The exhaust gas from the engine drives the pump wheel, which drives the turbine to rotate, and the turbine rotates to pressurize the air intake system.
The supercharger is installed on the exhaust side of the engine, so the working temperature of the supercharger is very high. When the supercharger works, the rotating speed of the rotor is very high, which can reach hundreds of thousands of revolutions per minute.
Such a high speed and temperature make the ordinary mechanical needle roller or ball bearing unable to work for the rotor, so the turbocharger generally adopts full floating bearing, which is lubricated by oil and cooled by coolant.
In the past, turbochargers were mainly used in diesel engines. Because gasoline and diesel are burned in different ways, the turbocharger used in the engine is also different.
A gasoline engine is different from a diesel engine. It is not air that enters the cylinder, but a mixture of gasoline and air, which is easy to explode when the pressure is too high. Therefore, the installation of turbocharger must avoid deflagration, which involves two related issues, one is high temperature control and the other is ignition time control.
Extended data:
Turbocharged engine, supercharger is small, pipeline layout is flexible, and air cooling and intercooling are mostly used. The air pressurized by the turbocharger is introduced into the heat exchanger in front of the engine, and part of the heat is blown away by the air before entering the engine.
The engine block needs coolant to provide heat dissipation, and the oil cooler and transmission oil cooler also introduce coolant to dissipate heat. The coolant itself also needs to be cooled by air cooling. But for supercharged engines, intake air also needs heat dissipation.
When gas is compressed, the external force releases energy to the gas, and the distance between gas molecules becomes smaller. Microscopically, the collisions between gas molecules become frequent and intense, and the internal energy increases. The end result is that heat is generated and the temperature rises.
In addition, the high-temperature exhaust gas turbine of the turbocharger is very close to the compressor that sucks air, so part of the heat will be transferred to the air that is about to enter the cylinder.
Pressurized air directly enters the combustion chamber, which will first affect the charging efficiency of the engine. High temperature air will expand in volume, decrease in density and lower in oxygen content than normal temperature air. When the oxygen content as combustion improver is insufficient, the engine will naturally lose power when running.