Controlled Combustion in an IC-Engine with a Fully Variable Valve Train

Two methods have been achieved of facilitating controlled auto-ignition (CAI) combustion in a 4-stroke engine. This has been accomplished without the need to pre-heat intake air and was made possible through the use of the Active Valve Train (AVT) system. AVT was used to vary the amount of trapped exhaust gasses (otherwise known as exhaust residuals) inside the cylinder prior to the compression stroke. Both methods represent examples of internal exhaust gas recirculation (EGR). It was observed that the amount of internal EGR determined the combustion initiation point as a function of crank angle, thus demonstrating that both methods are controllable reproducible processes. Initial results (taken at 2000rpm and 3.5bar IMEP) show that this combustion significantly reduces NOx emissions to ultra-low levels compared to conventional spark ignition combustion. Data presented here represents the first published results of our internal EGR methodologies. At present, this combustion is being investigated across a wide range of engine speed and load points. This data will be published in the near future.