Matching And Optimizing Of Diesel Engine For Omnibus With Variable Nozzle Turbocharger

With development of economy and improvement of people's life we pay attention to omnibus more and more. However the limitation of exhaust regulations is intensified increasingly, petroleum price is getting higher and higher, the request of bus corporation is getting stricter and stricter. So the reduction on fuel consumption of diesel for omnibus and the control of the particulate exhaust, the improvement of torque at low speed and response are the important problems which are need to be resolved as soon as possible. Meanwhile with the application of electrical technique on diesel, electrical technique has already become one of the most importance directions in the development of diesel technology. we can effectively reduce the diesel emission by Using the technology of diesel engine electronic control.For many years, turbochargers have been an add-on to reciprocating engines to increase air supply. Increased air permits higher fuel flow rates, which then led to increase power. At last as these advances approach maturity, the next turbocharger advancement requires the ability to vary operating characteristics. Using variable nozzle turbocharger can meet the demands. It has an adjustable turbine nozzle that acted like a small turbine for fast response at low speeds and a large turbine for maximum power and efficiency at high speed. It can vary the turbine's area by having movable blades at the turbine wheel. It also allow to have the feature of minimizing the turbo lag by decrease the flow area and then reduce exhaust gas restriction in high flow to achieve high power output. By using variable nozzle turbocharger (VNT), we can improve the torque of the engine at low speed, reduce the black smoke of engine. And improve the accelerating performance of the engine.This paper focuses on electronic VNT system matching on diesel engine for omnibus based on researching and analyzing characteristic run state of diesel for omnibus. For the purpose of improving power performance, improving fuel consumption and reducing the emission of diesel engine for omnibus.The main experiment of this paper including:1) Select characteristic urban road, then do omnibus road test, record speed and torque of diesel in all kinds of vehicle speed in whole test course. Deal with, summarize and analyze test data, gain characteristic run state of omnibus.2) Establish different control strategy on engine stable and transient status depending on VNT control characteristic. Adjusting with control parameter based on different engine state. Compile control sub-program in control system software.3) Matching VNT system on diesel engine. Investigating on how the vanes position of VNT affects the performance and emissions of engine in every operating point. We mainly consider the torque of low speed, fuel assumption,...