Potential of Multiple Injection Strategy for Low Emission Diesel Engines

Abstract

<div class="htmlview paragraph">A PC-programmable electronic control unit (PECU), able to manage both conventional and future electronic injection systems to make a fixed number of consecutive injections (1 to 5 or more) controlling the injection pressure and the injection pulses duration as well as the separation time or dwell in between was used to study the behaviour of a Bosch common rail injection system both on dynamic spray bench and on engine test bench. The PECU allowed a reduction in the dwell time between consecutive injection pulses from the current value of 1800 μs to 500 μs.</div> <div class="htmlview paragraph">Photographic sequences of a five holes mini-sac nozzle making five consecutive injections at 400 - 800 and 1200 bar respectively were taken at ambient pressure and temperature. They showed that both spray penetration and cone angle at all operative conditions are very uniform and stable.</div> <div class="htmlview paragraph">Preliminary engine tests carried out on a small DI diesel engine have shown that multiple injections contributes to a reduction in the peak heat release and the NOx and smoke exhaust emissions</div>