Abstract: A camshaft phaser includes a stator having a plurality of lobes and a rotor coaxially disposed within the stator and having a plurality of vanes interspersed with the lobes defining a plurality of alternating advance chambers and retard chambers such that a phasing valve supplies and vents oil to and from the advance and retard chambers. A first check valve allows oil to flow from only one of the retard chambers to only one of the advance chambers when a first diverter valve permits communication between the one of the advance chambers and the first check valve and a second check valve allows oil to flow from the one of the advance chambers to the one of the retard chambers when a second diverter valve permits communication between the one of the retard chambers and the second check valve.

Abstract: A camshaft phaser is provided for varying the phase relationship between a crankshaft and a camshaft in an engine. The camshaft phaser includes a stator having lobes. A rotor disposed within the stator and rotatable between a full retard position to a full retard position includes vanes extending radially outward from a central hub and interspersed with the stator lobes to define alternating advance and retard chambers. A first portion of the central hub between adjacent vanes extends radially outward further than a second portion of the central hub between adjacent vanes.