PARAMETER SELECTION AND MODELLING FOR COMPONENT MATCHING AND PERFORMANCE ENHANCEMENT OF A TWIN CHARGER SYSTEM ON VEHICLE IC ENGINES

摘要

Currently, the IC engines arc associated with severe drawbacks such as: SI engine average efficiency is substantially below its brake-specific fuel consumption, while CI engines although inherently more fuel-efficient than gasoline engines, cannot be less pollutant. In this context, the IC engines have shown specific control properties different from other air breathing systems. New distributed parameter control problems have been formulated for integration with developments such as downsizing and supercharging the SI engine, or extraction of maximum power from a CI (Diesel) fixed engine design with fixed dimensions by charge air boosting with various pumping or compressing systems of supercharging, turbocharging or dual charging type.The work of this paper is based on parameter selection for application in modelling and analysis of vehicle IC engine distributed parameter control systems with the aim of achieving the pre-defined desirable design properties and increased control stability.Especially it is expected that electronic control systems will improve the CI engine system. CI Diesel engines have been typically less advanced in electronic controller system due to cost, reliability and image problems. It is currently predicted that electronic control systems will contribute essentially to the reduction of pollutant emission of Diesel engines. The main objective for electronic Diesel engine control systems has been to provide the required torque with minimal fuel consumption under the constraints of exhaust gas emissions and noise regulations. In this context optimal coordination of injection, turbocharger and exhaust gas recirculation (EGR) systems in stationary and transient operating conditions is required. Three paths have been considered as the fuel, air and the EGR path.An improved vehicle Cl engine performance expressed through the engine torque controlled by changing the air/fuel ratio in the combustion chamber can be achieved through component matching of a dual charging system that integrates a turbochargcr and a twin-screw supercharging compressor with an electronic controller. It was anticipated that the shape control theory can be used for distributed parameter control of the vehicle Cl engine for prediction of the output torque, speed and exhaust gas emissions. Using the measurement of the air mass flow into the engine, the maximum quantity of injected fuel will be limited with the aim of reducing visible pollutants such as smoke.For theoretical analysis and feasibility study of this control idea parameter driven simulation results will be validated experimentally before this control method is fully defined and a control oriented model is described. Using this model, a suitable control structure will be derived and verified by both simulations and measurements.