Sport Utility Vehicle Refinement by Engine Upgrading and Gear Ratio Optimization

To improve the drivability and reduce fuel consumption and emissions of an existing sport utility vehicle (SUV), simulation-based vehicle refinement was conducted in this study. A simulation model of the SUV was first established and validated. Both simulation and test results confirm that due to low reserve power both at low and high speed bands, the drivability, fuel economy and emissions of the SUV are unsatisfactory. To refine the vehicle, complex precautions were implemented to upgrade the diesel engine, and the powertrain gear ratios were optimized with a design of experiments (DOE) approach to match the upgraded engine. Updated simulation results demonstrate that the refined vehicle is powerful enough at a sufficient speed range, with moderate fuel consumption at Euro III standard emissions. An interim vehicle prototype, with an upgraded engine but an unmatched transmission, was produced; field test results of the interim vehicle proved the effectiveness of the simulationbased SUV refinement. The final, fully refined SUV product is currently in development.