Fully hydrodynamic piston ring and cylinder assembly

摘要

A piston ring and cylinder assembly designed for fully hydrodynamic operation with oil control is disclosed. The rings are loaded in circumferential compression and are flexible. They conform instantaneously to cylinder wall distortions and oil film forces. The elastic properties of the ring, combined with the ring crown geometry maintain oil control (zero oil pumping to the top of the cylinder wall) with fully hydrodynamic conditions between ring and cylinder wall. The cylinder wall is finished to a very smooth surface and may be provided with a number of axial grooves near the top dead center position of the top ring so that oil is positively blown down from the top of the cylinder for oil control.