Hydrodynamic shaft seal

Claim 1

A shaft seal for use between a rotating shaft and a surrounding stationary housing under both static and dynamic conditions, said housing having an opening extending therethrough and receiving said shaft therein said shaft seal comprising an annular resilient seal body adapted to be fixed relatively to said housing in a position encircling said shaft said resilient seal body having a central axis coincident with that of said shaft and comprising an integral radially inwardly extending flexible inner portion terminating in a generally annular sealing face for sliding engagement with the periphery of said shaft, the liquid axial side of said seal body being exposed to a liquid to be sealed against leakage, and an outer annular spring-retaining groove located radially outwardly of said sealing face, and an annular coil spring mounted in said groove providing a radially inwardly directed force biasing said sealing face radially inwardly toward said shaft said sealing face including a continuous annular static portion with a narrow static sealing surface adjacent the other side of the seal for static sealing against said shaft, and a dynamic portion adjacent the liquid side of said seal body, including an annular liquid side surface on said liquid side of said seal body an imperforate annular outer surface of greater diameter than that of said static sealing surface, spaced radially outwardly from said shaft and extending axially from said static sealing surface toward said liquid side of said seal body and intersecting said liquid side surface, said outer surface having a plurality of peripherally spaced vanes extending radially inwardly and extending axially at an angle to the axis of said seal body, said outer surface and said vanes forming chambers therebetween open to said liquid side of said seal body, said spring force being effective under static conditions to urge said static sealing surface into contact with said shaft to prevent escape of liquid from said liquid side along said shaft, and being effective under high speed dynamic conditions to balance the radially outwardly directed hydrodynamic force against said outer surface and maintain both said static sealing surface and the inner surfaces of said vanes spaced radially outwardly from said shaft and to control said spacing to prevent escape of liquid from said liquid side along said shaft.