Reduced friction piston rings
View Patent ↗Improved liquid lubricated piston ring gas seals with reduced friction and wear compared to prior art rings are disclosed for use in internal combustion engines, gas pumps, and gas compressors. These improved rings allow independent adjustment of the parameters controlling friction and wear, and eliminate the tradeoff between friction and wear typical of prior art rings.
1. A liquid lubricated sliding gas seal employed to seal the annular gap between a generally cylindrical piston reciprocating in a generally cylindrical bore used in machinery including but not limited to internal combustion engines, gas pumps and gas compressors, wherein the piston axis tilts forming angular excursions relative to the bore axis during the course of the reciprocating motion; wherein
the gas seal is diametrically expandable, and comprises an outside diameter, an inside diameter; and upper and lower faces substantially perpendicular to the piston ring axis;
the piston has an annular ring groove comprising an upper flank, a lower flank and a bottom, and the piston is reciprocally moveable in a bore;
the piston ring is disposed in the ring groove such that the outside diameter of the gas seal is in liquid lubricated sliding contact with the cylinder bore surface, the inside diameter spaced away from the groove bottom forming an annular space, and the gas seal upper and lower faces are adjacent the upper and lower groove flanks respectively;
the annular space between the gas seal inner diameter and the groove bottom is in fluid communication with the gas above the ring such that its pressure is substantially equal to the gas pressure above the gas seal;
the gas seal outside diameter is divided by an annular fluid passage into generally cylindrical upper and lower zones, wherein the annular fluid passage is in fluid communication with the gas above the gas seal such that its pressure is substantially equal to the gas pressure above the gas seal;
the generally cylindrical lower zone serving a gas sealing function and the generally cylindrical upper zone serving a slider bearing function; and
accommodating means are provided to maintain the gas sealing function and the slider bearing function as the piston tilts relative to the bore;
the gas seal is a single ring component, the pressurized annular fluid passage dividing the generally cylindrical ring outside diameter is a circumferential groove, and the piston tilt accommodating means comprises a contour of the ring outside diameter wherein the lower sealing zone maintains contact with the bore as the piston tilts while the upper bearing zone maintains a small clearance;
the contour of the lower sealing zone comprises a radius forming a barrel shape and the upper bearing zone comprises a taper approximately tangent to the upper edge of the barrel shape radius;
the circumferential groove is in fluid communication with the gas above the ring through one or more axial grooves traversing the upper bearing zone;
the circumferential groove is in fluid communication with the gas in the annular space between the piston ring inner diameter and the groove bottom through one or more radial passages within the ring connecting the groove and the annular space.
2. The piston ring gas seal according to claim 1 wherein the contour of the lower sealing zone comprises a radius forming a barrel shape and the upper bearing zone comprises a taper approximately tangent to the upper edge of the barrel shape radius, the included angle of the taper equal to or greater than the maximum angular excursion of the piston.