Patent ID: 7938091

Claim:
A camshaft adapted to be rotatably coupled to a shaft bearing part of an engine, the camshaft comprising: a cam lobe having a base circle portion and a lifting lobe portion, and configured and arranged to operate one of an intake valve and an exhaust valve; and a camshaft journal having a first bearing portion configured and arranged to bear a reaction force from the base circle portion of the cam lobe and a second bearing portion configured and arranged to bear a reaction force from the lifting lobe portion of the cam lobe, an axial end surface of the first bearing portion facing an axial end surface of the lifting lobe portion of the cam lobe, and an axial end surface of the second bearing portion facing an axial end surface of the base circle portion of the cam lobe, the first bearing portion of the camshaft journal having an axial width that is smaller than an axial width of the second bearing portion with at least a portion of the axial end surface of the first bearing portion being disposed further away from the cam lobe with respect to the axial end surface of the second bearing by a first prescribed distance, and the base circle portion of the cam lobe having an axial width that is smaller than an axial width of the lifting lobe portion with at least a portion of the axial end surface of the base circle portion being disposed further away from the camshaft journal with respect to the axial end surface of the lifting lobe portion by a second prescribed distance, the cam lobe being disposed adjacent to the camshaft journal such that a minimum axial spacing between axially opposing surfaces of the cam lobe and the camshaft journal is substantially equal to a prescribed axial spacing that is a minimum allowable spacing determined based on at least one of a casting requirement associated with cast forming the camshaft and a performance requirement of the camshaft.