A review of internal combustion engine losses - Part 1: specific studies on the motion of pistons, valves and bearings

Energy saving is an important task today. Friction reduction in reciprocating engines is a way to reduce fuel consumption and to improve engine endurance. To find the value of frictional losses of every component is necessary in order to reduce engine losses. The piston-liner system, valve train and bearings are the most important components for mechanical friction losses in reciprocating engines. In this paper both theoretical and experimental works published within the last ten years about the losses related to the motion of pistons, valves and bearings have been reviewed. Some known design improvements to reduce friction in these components are briefly reported and indications for future developments are pointed out, related in particular to the numerical approach, capable of more realistic simulations due to new software and hardware, and to the new experimental and material technologies.