Let's learn about the type of turbocharging.
According to the utilization of exhaust energy in the turbine, it can be divided into the following two systems:
Turbocharged constant pressure turbocharging system: the constant pressure turbocharging system collects the exhaust from all the cylinders of the internal combustion engine into a large enough exhaust pipe, and then introduces the turbine. Although each cylinder is discharged alternately, the pressure at the inlet of the turbine is basically unchanged due to the pressure stabilization of the exhaust pipe, so it is called a constant pressure supercharging system. The main advantages of constant pressure turbocharging are: turbine full-cycle intake under constant pressure, high efficiency; less excited vibration caused by air flow, not easy to cause blade fracture; simple exhaust system, low cost, easy layout and maintenance.
The main disadvantage is that the utilization rate of pulse energy is low. Experiments show that when the pressurization pressure is small, the constant pressurization system uses only 12%-15% of the exhaust energy, and can reach more than 30% at high pressurization.
In addition, the constant pressure turbocharged internal combustion engine has poor low speed torque characteristics and acceleration performance.
Turbocharged pulse turbocharging system: the pulse turbocharging system is designed to improve the efficiency of energy loss in the constant pressure system. The characteristic of this scheme is that the exhaust pipe is short and thin, and the solution of the exhaust system should be as small as possible, so that the exhaust can expand directly into the turbine and reduce throttling loss.
In addition, in order to reduce the mutual interference of the exhaust pressure waves of each cylinder, two or more exhaust branches are often used to separate the exhaust of the adjacent cylinder. The pulse system can make better use of the exhaust energy of the internal combustion engine than the constant pressure system, and the smaller the exhaust pipe volume, the better, so that in recent years, there has been a compact structure of turbocharger and exhaust pipe.