Patent ID: 8322318

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 housing having a bore with a longitudinal axis; a harmonic gear drive unit disposed radially within said housing, said harmonic gear drive unit comprising a circular spline and an axially adjacent dynamic spline, a flexspline disposed radially within said circular spline and said dynamic spline, a wave generator disposed radially within said flexspline, and a rotational actuator connectable to said wave generator, wherein one of said circular spline and said dynamic spline is fixed to said housing in order to prevent relative rotation therebetween; a hub rotatably disposed radially within said housing axially adjacent to said harmonic gear drive unit and attachable to said camshaft and fixed to the other of said circular spline and said dynamic spline in order to prevent relative rotation therebetween; a first advance stop surface fixed to a first surface and projecting axially from said first surface toward a second surface, wherein said first surface is rotatable with one of said circular spline and said dynamic spline and wherein said second surface is rotatable with the other of said circular spline and said dynamic spline; a first retard stop surface fixed to said first surface and projecting axially from said first surface toward said second surface; a second advance stop surface fixed to said second surface and projecting axially from said second surface toward said first surface; and a second retard stop surface fixed to said second surface and projecting axially from said second surface toward said first surface; wherein said first and second advance stop surfaces overlap axially and radially to limit angular travel between said circular spline and said dynamic spline when said camshaft phaser is phasing said camshaft in the advance direction, and wherein said first and second retard stop surfaces overlap axially and radially to limit angular travel between said circular spline and said dynamic spline when said camshaft phaser is phasing said camshaft in the advance direction.