Optimal Design Of Air Injection System For Bus Turbocharged Diesel Engine In Standing Start Acceleration Process

Turbocharger response lag causes a significant increase of diesel soot in bus standing start acceleration process, which can be solved by air injection to some extent. The numerical model of CA6DL1-26E3 diesel engine is simulated b y employing the GT-Power software, and the electronic controlled air injection device is optimized. The research results have better project application values in reducing diesel soot. The key research work and results are as follows:(1) The simulation m odel of CA6DL1-26E3 diesel engine is established by employing the GT-Power software. Aiming at the standing start acceleration process of XMQ6116G3 diesel bus, the impacts of air pressure, pipe diameter and lead time on diesel soot are studied as the focus. Simulation results demonstrate that, if the pipe diameter is 12 mm, the su itable pressure of air reservior is 10-12bar; if the pressure of air reservior is 8bar, the suitable pipe diameter is 16mm; air injection can further reduce diesel soot, and 1 second lead time can meet the requirements.(2) After the correlation analysis of operational motions among turn signal, brake pedal, handbrake, clutch, transm ission and throttle pedal, and analysing the relationship among transmission in second gear, throttle opening, engine speed and vehicle speed, the advance air injection technical solution is put forward. In this solution, shifting into second gear is taken as the trigger signal of judging standing start acceleration condition.(3) The air injection strategy of former system is optimized. When the engine at idle speed and vehicle speed is zero, taking shifting into second gear as the benchmark, after a set time delay, the solenoid valve is opened to start air injection. When the engine speed reaches a set rotating speed, the solenoid valve is closed, and air injection is finished. The delay time between shifting into second gear and opening solenoid valve has sel f-adaptability control strategy. This strategy realizes advance air injection technical scheme and enhanced its adaptation to different drivers.(4) According to the optimized scheme, advance air injection system for diesel bus in standing start acceleration c ondition is developed. Vehicle test results show that, this system can accomplish expectant air injection control. Bench test results show that, diesel soot in bus standing start acceleration condition is further reduced by optimizing.