Piston oil-cooling device in an engine

摘要

A piston is reliably cooled from its backside by using an oil for lubricating portions around a crank pin of a crankshaft. An engine including a crankshaft is provided with lubricating oil bores to supply an oil from journals of the crankshaft to an outer peripheral surface of a crank pin. A larger end of the connecting rod is provided with a pair of opposed axial oil grooves in its outer peripheral surface, and with an annular oil passage connected to the axial groove in its side thrust face. A pair of cooling oil injection grooves each have one end connected to the annular oil passage and the other end directed to a piston while they are provided proximate to each other.