Patent ID: 8424500

Claim:
A camshaft phaser for controllably varying the phase relationship between a crankshaft and a camshaft in an internal combustion engine, comprising: a hub having a substantially cylindrical outer surface of a diameter D 1 ; a housing having a diameter D 2 , said diameter having a substantially cylindrical inner surface, wherein said housing is configured for rotably receiving said hub, in a close fit, wherein said substantially cylindrical inner surface of said housing diameter is adjacent a substantial portion of said substantially cylindrical outer surface of said hub to define a journal bearing interface, and wherein said journal bearing interface has a length L; and a harmonic gear drive unit having an input element and an output element, wherein said input element is connected to one of said hub and said housing and wherein said output element is connected to the other of said hub and said housing; wherein the ratio of length L to diameter D 1 is selected to provided axial stability between said hub and said housing; and wherein the ratio of length L to diameter D 1 is equal to or greater than approximately 0.25.