Optimization of the Bearing Oil Supply Concept of a High Power- Density Diesel Engine to Minimize Oil Pump Friction
Reducing the mechanical friction of an internal combustion engine plays a major role in improving the brake specific fuel consumption (BSFC) at the engine level. Hence, it is important to reduce the friction at every component and sub-system level. In the present work, the oil pump friction of a 1.5 litre 4-cylinder diesel engine is optimised by reducing the oil pump displacement volume by 20%. This could be achieved by adapting an optimised oil supply concept which could reduce the oil leakage through main bearings and connecting rod bearings. A 1-dimensional oil flow simulation was carried out to predict the oil flow distribution across the engine at difference speeds. The results indicate that the oil leakage through main bearings and connecting rod bearings contribute to ~25% of the total oil flow requirement of the engine. In a conventional oil supply concept, the big-end bearing of each connecting rod is connected to the adjacent main bearing through an internal oil hole.