Oil supply route in a camshaft for a cam phaser

An internal combustion engine including a cam phaser assembly for shifting rotational phase between an engine crankshaft and camshaft, wherein said cam phaser assembly includes:

• a camshaft having a blind axial bore of a first diameter extending inwards from an end of said camshaft, first and second annular grooves formed in an outer surface of said camshaft for supplying advancing and retarding oil to said assembly, said grooves being axially spaced apart and communicating via first and second radial bores, respectively, with said blind axial bore;
• a cam phaser disposed on said end of said camshaft and having distribution passages therein for advancing and retarding oil and having a central aperture;
• and
• a bolt disposed through said central aperture and threadedly engaged in said blind axial bore for securing said phaser to said camshaft, said bolt having a second diameter less than said first diameter such that an annular oil passage is provided in said assembly between said bolt and said blind axial bore communicating between said first annular groove and said cam phaser, said bolt having an axial bore communicating with said second radial bore in said camshaft for providing one of said advancing and retarding oil to said phaser.