Mechanically driven centrifugal air compressor with hydrodynamic thrust

Abstract

A mechanically driven centrifugal air compressor for an internal combustion engine has an impeller shaft supported in a compressor housing with journal bearings. A helical pinion gear is formed on one end of the impeller shaft and an impeller is attached to the other end. A thrust ring mounted on the impeller shaft near the impeller is sandwiched on one side by a thrust bearing and on an opposite side by the nearest journal bearing and the housing to axially locate the impeller shaft. An internal helical ring gear is rotatably supported on the compressor housing and driven by a pulley that is engaged by a belt that is driven by a pulley of larger diameter fixed to an engine crankshaft. The ring gear meshes with the pinion gear to provide a high overdrive speed ratio in series with the belt and pulley drive from the engine crankshaft which provides a low overdrive speed ratio. The thrust bearing bears the axial load on the impeller shaft imposed by air pressure acting on the impeller and the lead of the helical pinion gear is set in a direction so that the gears impose an axial force on the impeller shaft that is opposite the impeller imposed axial force to substantially reduce the axial load borne by the thrust bearing. The thrust bearing is provided with a plurality of oil pockets opposite the thrust ring having a depth that decreases from a deep end in the direction of thrust ring rotation. And passages are provided for delivering oil under pressure to the deep end of the oil pockets to hydrodynamically transfer the net axial load on the impeller shaft from the thrust ring to the thrust bearing.