Patent ID: 8683965

Claim:
A camshaft assembly comprising: a camshaft including a first shaft defining an axial bore, a second shaft located within the axial bore of the first shaft and rotatable relative to the first shaft, the second shaft including an axially extending cavity in an end thereof, a first cam lobe located on the first shaft and fixed for rotation with the first shaft and a second cam lobe supported for rotation on the first shaft and fixed for rotation with the second shaft; a drive member fixed to a first axial end of the camshaft and rotationally driven to drive rotation of the camshaft; and a camshaft actuation assembly including an actuator coupled to a second axial end of the camshaft and rotationally fixed to an engine structure and relative to the camshaft, wherein the actuator is engaged with the first and second shafts and rotationally drives the second shaft relative to the first shaft, wherein the first shaft defines a first set of helical splines on an interior surface of the axial bore and the second shaft defines a second set of helical splines on an exterior surface of the second shaft, the actuator including a piston defining a cylindrical wall at least partially located within the axial bore of the first shaft and surrounding an end of the second shaft and being axially displaceable relative to the camshaft, the piston having an outer circumference of the cylindrical wall defining a third set of helical splines engaged with the first set of helical splines and an inner bore of the cylindrical wall defining a fourth set of helical splines engaged with the second set of helical splines, axial displacement of the piston providing rotation of the second shaft within the first shaft, wherein the first and third sets of helical splines are oriented in a first rotational direction and the second and fourth sets of helical splines are oriented in a second rotational direction opposite the first rotational direction, wherein the actuator includes a biasing member disposed within the cavity in said second shaft and engaged with the piston and the second shaft and biasing the piston in a direction axially outward from the second shaft.