Abstract
In this study, we combined a diesel engine with a hybrid system developed by our company (THS) for better fuel economy. However, the THS could not be utilized to its full advantage, since a conventional diesel engine has high NOx emissions in high load where fuel economy is good. Therefore, reducing engine friction, lowering the compression ratio, and a low pressure loop exhaust gas recirculation system (LPL-EGR) were examined to achieve both low fuel consumption and low NOx emissions over a wide operating range. Applying this system to a test vehicle, it was verified that the fuel economy greatly surpassed that of a conventional vehicle and that NOx emissions could be reduced below the Euro 6 regulations without DeNOx catalysts.
