Piston ring for four-stroke internal-combustion engine

摘要

A conventional piston ring for the piston of a four-stroke internal-combustion engine is purposely re-machined so that at least in one specific angular area extending on both sides of the ring gap the running surface is partially removed so that a contour partially set back from the normal round form and hence at least one defined lubricating oil passage is produced. The cross sectional area of such a lubricating oil passage produced between the set-back wall surface on the piston ring and the cylinder running surface determines the extent of oil permeability. Indirectly secured against rotation, such a piston ring is held in the ring groove so that the one lubricating oil passage is arranged in the area of the pressure side of the piston.