Study On The Matching And Controlling Of Variable Nozzle Turbocharger (VNT) And Diesel Engine

Due to the superiority at power, energy-saving and emission, diesel engine has become technology of saving energy for cars. And the trend that most of cars use diesel as energy has been formed. Turbocharged diesel engine technology is being applied more and more widely. The study of the matching and controlling of the variable nozzle turbocharger in this paper is a part of the project that "development of the new generation of highly efficient diesel engine for the Chang feng cars" which is supported by the Ministry of Science and Technology, aimed to improve the weakness of the conventional turbocharged which contains not enough torque at low speed, poor economy at part load and slow response for transient condition.In this paper, physical subsystem model of the turbocharged diesel engine is build and the working process is analyzed. Based on that, creates a GT-Power simulation model of DOl diesel engine. Adjust the model by comparing to the experiment data.With the simulation computation model of variable nozzle turbocharger, the matching principles between variable nozzle turbocharger and DOl diesel engine have been investigated and analyzed in this paper. And get the data of the nozzle opening and boost pressure. Analysis the influences on the engine power and economic of the nozzle opening, and then determines the best nozzle opening with the engine speed and load variation.With analysis of the matching results between the engine and the VNT, we determine control strategy for all working conditions:PID feedback control with boost pressure for steady state, rack position as the target for typical operating conditions of the transient state, and determine the nozzle opening by judging the water temperature on idling condition. After that, we build the VNT control system model in Simulink.After completed the design of the Executive body, we choose the motor and sensor. And then build the hardware in loop system with the platform of dSPACE with which the executive body is connected to the control model; achieve debugging software and hardware by taking position feedback control. After the experiment, we find that the system is steady, and response is quick enough to satisfy the system requirements.