In order to improve the performance of a reciprocating engine by reducing friction loss the authors have studied some characteristics of total friction loss of engine, friction of piston assembly and friction of cam / follower.
Firstly, the total friction loss is accurately measured by a convenient engine run-out method to examine the change of total friction mean effective pressure with engine speed, load rate and oil temperature in a fired and braked engine. The influence of piston / cylinder assembly exchange from the worn to the unworn on friction is then examined, followed by the difference of friction loss between SAE30 and SAE10W-30 engine oils.
Secondly, the cyclic change of piston assembly friction under the firing condition is measured by an improved floating liner method. Also, the friction characteristics of piston rings are investigated by comparing results with the theoretical values predicted in the mixed lubrication regime under the oil starvation condition.
Lastly, the friction characteristics of cam / follower interfaces in the valve train system are experimentally examined by using a test apparatus in which the friction force between cam and follower is directly measured. Particularly for the ceramic follower, the friction is characterized as the change of the friction mean effective pressure.