An Investigation with Mechanical Supercharging as Boosting Solution on Less than 0.5 Liter Single Cylinder Diesel Engine towards Bharat Stage VI Emission Development

摘要

Small single & two cylinder diesel engines, still have primitive technical design features and extensively used in India and various Asian countries to power small and light motor vehicles viz., three wheelers, light duty four wheelers. These vehicles have become inevitable for the transport for both urban and rural areas. Vehicles with small single & two cylinder engines have high market demand in commercial transport due to restrictions on entry of Heavy Commercial Vehicles (HCV) in congested cities roads. Due to ever rising market demand for higher power and torque requirement along with better fuel economy, vehicle manufacturer are developing high Brake Mean Effective Pressure (BMEP) engines or replacing single cylinder engine by two cylinder engine, similarly two cylinder engine by three cylinder engines. Further, these engines should meet the present and forthcoming stringent emission limits. Single cylinder and two cylinder small diesel engines are widely used in various applications like Light Commercial Vehicle (LCV), power generation, three wheelers, agricultural machines and small house-hold applications in India as well as other Asian countries. Therefore simple mechanically controlled components are used for these engines which make them simple in operation with low maintenance and cost effective. Several studies & research work so far conducted on these small single engine have revealed that, successful & economically acceptable turbocharging of single cylinder diesel engine is not yet achieved. This is due to its phase mismatch between intake and exhaust stroke timings, long gap between two exhaust stroke and continuous flow of exhaust gas to drive the turbine wheel efficiently. This paper addresses the problems through mechanical supercharging. For this research work, a small 0.4 liter, three wheeler (3W), naturally aspirated, air-cooled, single cylinder DI diesel engine, equipped with mechanical fuel injection system, is used. A roots type supercharger, driven mechanically from a drive pulley directly mounted on crankshaft, is used for boosting the engine. Experiments were conducted with various engine parameters, settings and step-up ratios of the drive pulley. The results show an observed increase in engine power more than 20% throughout the full load curve and favorable emission levels with respect to the base BS III compliant single cylinder engine. The experimental outcomes and reviews which are required to arrive at adequate boosting to enhance the performance & emissions of the engine are reported.