An engine variable camshaft timing phaser (10) includes a sprocket (12) and a planetary gear assembly (14). The sprocket (12) receives rotational drive input from an engine crankshaft. The planetary gear assembly (14) includes two or more ring gears (26, 28), multiple planet gears (24), a sun gear (22), and a wrap spring (76). One of the ring gears (26, 28) receives rotational drive input from the sprocket (12) and one of the ring gears (26, 28) transmits rotational drive output to an engine camshaft. The sun gear (22) engages with the planet gears (24). The wrap spring (76) experiences expansion and contraction exertions to permit advancing and retarding engine valve opening and closing, and to prevent advancing and retarding engine valve opening and closing.

A valve gear for an engine, includes: a camshaft phase varying device by which a rotational phase of a camshaft for opening/closing valves of the engine can be changed relatively to that of a crankshaft; and a holder that is provided so that the holder can be removably attached to the camshaft in a state where the holder has held constituent components of the camshaft phase varying device.

An engine may include an electric continuously variable valve timing apparatus for adjusting opening timing of an intake valve provided at a cylinder head, and a continuously variable valve duration apparatus for adjusting duration of exhaust valve provided at the cylinder head.

A camshaft unit (1), having a first camshaft (2) which is phase-adjustable with respect to a crankshaft, having a second camshaft (3) which is arranged concentrically with respect to the first camshaft (2), and having a camshaft adjuster (5) by which both camshafts (2, 3) are phase-adjusted with respect to the crankshaft.

Systems and methods for varying a rotational relationship between a cam shaft and a crank shaft on an internal combustion engine (i.e., cam phasing) are provided. In particular, systems and methods are provided that facilitates a rotary position of a first component to be accurately controlled with a mechanism causing a second component, which can be coupled to the cam shaft or crank shaft, to follow the rotary position of the first component.

A valve opening-closing timing control device includes an eccentric member that meshes an external teeth portion of an input gear with an internal teeth portion of an output gear. A concave portion on the eccentric member allows a spring member to be arranged in the concave portion. The spring member applies biasing force of meshing the external teeth portion with the internal teeth portion. The concave portion includes a spring support surface that receives biasing force of the spring member. When viewed in a direction along an eccentric axis, a top surface on the spring support surface has a smaller protrusion amount at a circumferential-direction central position of the spring support surface, as compared to an eccentric arc surface whose center is the eccentric axis.