오프로드 모빌리티용 800cc 소형 가솔린 엔진의 노킹 예측 및 점화시기 최적화에 대한 수치적 연구

Abstract

This study uses 1D-simulation to develop off-road gasoline MPI turbo engine. The SI Turbulent flame model of GT-suite, an operational performance predictable program, present turbocharger matching and operation optimal design points. In order to optimize engine performance, SI Turbulent model use three operation parameters of spark timing, intake valve overlap, and boost pressure. Spark timing, one of the variables, determines the initial state of combustion and thermal efficiency as the main variables of the engine. The maximum brake torque (MBT) point can be identified for spark timing, and abnormal combustion phenomena such as knocking can be identified. The parameter spark timing is related to engine performance and emissions of exhaust pollutants is predictable. If the spark timing is set to variables, engine performance and emissions can be relationship confirmed and predicted. Intake valve overlap can predict performance and exhaust gas by controlling air flow and combustion chamber flow, and can control performance by grasping the flow in cylinder. In addition, criterion can be set to take into account the optimum operating point of the non-road vehicle while investigating the performance and exhaust gas emissions accompanying changes in boost pressure. With these parameters, DoE (Design of Experiment) of 1D-simulation is performed and the driving performance and knocking phenomenon for each RPM are predicted during WOT(Wide Open Throttle) of gasoline MPI Turbo SI engine. The Multi-Objective Pareto technique was also used to optimize engine performance and emissions of exhaust gases, and to present optimized design points for the target engine, the downsized gasoline MPI Turbo SI engine. The results of the Pareto optimal solution showed a torque increase of maximum 12.78% and a NOx decrease of 54.31%.