Camshaft phaser

A camshaft phaser for use with an internal combustion engine for controllably varying the phase relationship between a crankshaft and a camshaft in said internal combustion engine, said camshaft phaser comprising:

• an input member connectable to said crankshaft of said internal combustion engine to provide a fixed ratio of rotation between said input member and said crankshaft;
• an output member connectable to said camshaft of said internal combustion engine and defining an advance chamber and a retard chamber with said input member;
• a camshaft phaser attachment bolt which clamps said camshaft phaser to said camshaft, said camshaft phaser attachment bolt having a bolt valve bore extending along an axis, a bolt advance passage providing fluid communication between said advance chamber and said bolt valve bore, and a bolt retard passage providing fluid communication between said retard chamber and said bolt valve bore;
• a valve sleeve coaxially within said bolt valve bore such that an annular clearance is defined radially between said valve sleeve and said bolt valve bore, said valve sleeve having a sleeve bore, a sleeve advance passage proving fluid communication between said bolt advance passage and said sleeve bore, and a sleeve retard passage providing fluid communication between said bolt retard passage and said sleeve bore;
• a valve spool within said sleeve bore, said valve spool being displaced axially within said sleeve bore between 1) an advance position which directs oil into said retard chamber and vents oil from said advance chamber, thereby causing said output member to rotate relative to said input member in an advance direction and 2) a retard position which directs oil into said advance chamber and vents oil from said retard chamber, thereby causing said output member to rotate relative to said input member in a retard direction;
• and
• a compliant sealing ring radially between said bolt valve bore and said valve sleeve which engages said bolt valve bore and said valve sleeve, said sealing ring preventing fluid communication through said annular clearance axially between opposing axial sides of said sealing ring and said sealing ring also accommodating radially inward expansion of said camshaft phaser attachment bolt within said annular clearance such that said sealing ring isolates said valve sleeve from radial expansion of said camshaft phaser attachment bolt.