A variable camshaft timing system including a first camshaft phaser having an input that is configured to receive rotational force from a crankshaft and an output that is configured to link with a first camshaft of a concentric camshaft assembly to change the angular position of the first camshaft relative to a crankshaft; and a second camshaft phaser having an output that is configured to link with a second camshaft of the concentric camshaft assembly to change the angular position of the second camshaft relative to the crankshaft, wherein the first camshaft is concentrically positioned to the first camshaft and the first camshaft phaser is mechanically linked to the second camshaft phaser to communicate rotational force from the crankshaft to the second camshaft phaser through the first camshaft phaser and the mechanical link.

A variable camshaft timing system including a first camshaft phaser having an input that is configured to receive rotational force from a crankshaft and an output that is configured to link with a first camshaft of a concentric camshaft assembly to change the angular position of the first camshaft relative to a crankshaft; and a second camshaft phaser having an output that is configured to link with a second camshaft of the concentric camshaft assembly to change the angular position of the second camshaft relative to the crankshaft, wherein the first camshaft is concentrically positioned to the first camshaft and the first camshaft phaser is mechanically linked to the second camshaft phaser to communicate rotational force from the crankshaft to the second camshaft phaser through the first camshaft phaser and the mechanical link.

The present disclosure employs a pair of camshafts for intake valves. A first phase controller is installed at a first end of the first intake camshaft connecting to a crankshaft. A second phase controller is installed at a second end of the first intake camshaft connecting to a second intake camshaft. Each phase controller can advance or retard phase angles to modify intake valve timing and intake valve lift. This set up is duplicated for the exhaust valves to modulate exhaust valve timing and exhaust valve lift. First and second camshafts are connected via a series of levers, which merge rotational outputs of both camshafts into one. The phase controllers can be differential gear sets, epicyclical gear sets, or a combination thereof.

A valve timing system including a crankshaft drive gear coupled to the crankshaft in working communication with a crankshaft connecting rod gear further including a primary connecting rod disc with a first-journal, the first-journal configured to receive at least two connecting rods at respective first-rod-ends in a side-by-side orientation and each connecting rod is coupled to a respective one of the intake disc and the exhaust disc via an intake-journal and an exhaust-journal, respectively. At least two secondary connecting rod discs are coupled to at least two plate-shaft drive gears to drive at least two plate-shaft-gears, the two plate-shaft-gears are connected to the two plate-shafts, respectively. At least two plate-shafts are coupled to an intake cam-groove plate and an exhaust cam-groove plate, the intake cam-groove plate and the exhaust cam-groove plate cammingly-manipulate the intake valve stem connector and the exhaust valve connector to drive each valve assembly.

The present disclosure employs a pair of camshafts for intake valves. A first phase controller is installed at a first end of the first intake camshaft connecting to the crankshaft. A second phase controller is installed at a second end of the first intake camshaft connecting to the second intake camshaft. Each phase controller can adjust phase angle accordingly to modify intake valve timing and intake valve lift. This set up is duplicated for the exhaust valves to modulate exhaust valve timing and exhaust valve lift. First and second camshafts are connected via a series of levers, which merges the rotations of both camshafts into one. The phase controllers can be differential gear sets, epicyclical gear sets, or a combination thereof.

A variable camshaft timing system including a first camshaft phaser having an input that is configured to receive rotational force from a crankshaft and an output that is configured to link with a first camshaft of a concentric camshaft assembly to change the angular position of the first camshaft relative to a crankshaft; and a second camshaft phaser having an output that is configured to link with a second camshaft of the concentric camshaft assembly to change the angular position of the second camshaft relative to the crankshaft, wherein the first camshaft is concentrically positioned to the first camshaft and the first camshaft phaser is mechanically linked to the second camshaft phaser to communicate rotational force from the crankshaft to the second camshaft phaser through the first camshaft phaser and the mechanical link.

A valve timing control device for an internal combustion engine includes: a driving rotation member, a driven rotation member, a speed reduction mechanism, a circumferential clearance of the each of the rolling member being formed within an angle range of 0.01 to 0.4 in a circumferential direction from a reference line extending from a rotation axis of the driving rotation member in a radial direction, in a space constituted by the eccentric rotation member, the internal teeth constituting section, and the one of the holding holes.