Patent ID: 8726866

Claim:
A camshaft phaser for controllably varying the phase relationship between a crankshaft and a camshaft in an internal combustion engine, said camshaft phaser comprising: a stator having a plurality of lobes and connectable to said crankshaft of said internal combustion engine to provide a fixed ratio of rotation between said stator and said crankshaft; a rotor coaxially disposed within said stator and having a plurality of vanes interspersed with said stator lobes defining alternating advance chambers and retard chambers, wherein said advance chambers receive pressurized oil in order to change the phase relationship between said crankshaft and said camshaft in the advance direction and said retard chambers receive pressurized oil in order to change the phase relationship between said camshaft and said crankshaft in the retard direction, said rotor being attachable to said camshaft of said internal combustion engine to prevent relative rotation between said rotor and said camshaft; a camshaft phaser attachment bolt extending coaxially through said rotor and threadably engageable into said camshaft to attach said camshaft phaser to said camshaft, said camshaft phaser attachment bolt having a stepped bore for communicating pressurized oil from said internal combustion engine to said advance chambers and said retard chambers, said stepped bore defined by a larger diameter bore, a smaller diameter bore, and a shoulder between said larger diameter bore and said smaller diameter bore; a check valve assembly to prevent oil from being communicated from said advance chambers and said retard chambers to said internal combustion engine, said check valve assembly comprising a check valve body axially moveable within said larger diameter bore; wherein said check valve body includes a plurality of azimuthally spaced guiding walls, a plurality of clearance walls separating said guiding walls, and a seating surface at one end of said guiding walls and said clearance walls for selectively seating with said shoulder to prevent fluid communication between said larger diameter bore and said smaller diameter bore, said guiding walls riding closely against said larger diameter bore and said clearance walls spaced inward from said larger diameter bore to allow oil to flow between said clearance walls and said larger diameter bore when said seating surface is not seated with said shoulder.