CHARACTERISTICS OF PISTON-RING FRICTION - (INFLUENCES OF LUBRICATING OIL PROPERTIES)

In reciprocating internal combustion engines, one of the most importan t issues is to clarify the complicated frictional characteristics betw een the piston ring and the cylinder liner because of the demand for r educed frictional loss, as well as a solution of problems such as scuf fing and wear, that has accompanied the recent progress in engine perf ormance. In the present study, the floating liner method, in which the cylinder liner was supported by means of hydrostatic bearings, was de veloped to measure accurately the frictional force of the piston assem bly as a function of the crank angle in an operating diesel engine. Th e influences of engine operation conditions (engine speed, cylinder wa ll temperature, and gas pressure in the cylinder), lubricating oil vis cosity, polymer-containing multigrade oils, and a friction modifier on the frictional characteristics were evaluated on the basis of the exp erimental results obtained using this equipment.