NVH characteristics of air-assisted direct injected (DI) spark ignition four-stroke engines

摘要

The ability to run unthrottled or with partial throttling at part load combined with stratified combustion potentially gives direct injection (DI) gasoline engines significant fuel consumption reductions. These combustion changes alter the timing, amplitude and frequency content of the cylinder pressures. This paper examines the NVH changes on four stroke gasoline engines due to DI with an emphasis on Orbital's air assisted system. A combustion noise model which calculates direct and indirect noise from cylinder pressure data is discussed. The application of DI to four stroke engines requires specific subsystems and the effects of these are also reviewed.