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, includes a camshaft phasing mechanism that selectively changes an angular position of an input relative to an output; a first camshaft phaser sprocket, coupled with the input of the camshaft phasing mechanism, configured to engage a first endless loop that communicates rotational force from a crankshaft to the input of the camshaft phasing mechanism; and a second camshaft phaser sprocket, axially spaced from the first camshaft phaser sprocket and coupled with the output of the camshaft phasing mechanism, configured to engage a second endless loop that communicates rotational force from the output of the camshaft phasing mechanism to a camshaft and change the angular position of the camshaft relative to the crankshaft, wherein the camshaft phasing mechanism is mounted about an axis that is different from an axis of camshaft rotation.

A camshaft assembly for an internal combustion engine is provided. The camshaft assembly includes a first gear; a second gear; a hydraulically driven phasing assembly configured for varying the relative phasing of the second gear with respect to the first gear; and an idler shaft supporting the first gear. A method of constructing a camshaft assembly for an internal combustion engine is also provided. The method includes fixing a first gear and a second gear together via a hydraulically driven phasing assembly configured for varying the relative phasing of the second gear with respect to the first gear; and providing the first gear on an idler shaft.

A variable camshaft timing device adjusts phase between a camshaft and a crankshaft and includes a first ring gear configured to connect to the camshaft and rotate about a center axis, having a plurality of radially-inwardly facing gear teeth; a second ring gear axially spaced from the first ring gear, configured to receive rotational input from the crankshaft and rotate about the center axis, having a plurality of radially-inwardly facing gear teeth; a planetary gear assembly including one or more planet gears that are configured for rotation by an electric motor and engage the first ring gear and the second ring gear through the planet gear(s); and a cushioned stop configured to transmit energy between the planetary gear assembly and a planetary gear stop attached to a sprocket or a camshaft plate.

A control device has two modes as control modes of an electric power supply to an electromagnetic solenoid, which are used when a first determining unit determines that a difference between a sensed value of a phase and a target value of the phase exceeds a permissible range. One of the modes is a special mode that is used when a second determining unit determines that the sensed value of the phase reaches a threshold value. Another one of the modes is a normal mode that is used when the second determining unit determines that the sensed value of the phase does not reach the threshold value. In the special mode, the control device controls supply of the electric power to the electromagnetic solenoid in such a manner that an opening degree of an advancing port is larger than the opening degree of the advancing port in the normal mode.

A spark-ignited gas engine system comprises a combustion chamber defined by a piston, a head with a spark plug mechanism, and a cylinder having an associated intake valve and an associated exhaust valve, into which a mixture of combustible gas and air is entered via an intake manifold of the engine to drive a crankshaft. The system further comprises at least one turbocharger to compress the mixture. The system further comprises at least one camshaft, driven by the crankshaft via a gear assembly connected to the crankshaft, that comprises at least one cam that actuates the intake valve and the exhaust valve, at least one camphaser, coupled to the crankshaft via the gear assembly, and a controller to adjust a cam angle operation of the intake valve and the exhaust valve by adjusting the camphaser to a desired phase position to meet a target rotational phase of the camshaft.

A camshaft assembly for an internal combustion engine is provided. The camshaft assembly includes a first gear; a second gear; a hydraulically driven phasing assembly configured for varying the relative phasing of the second gear with respect to the first gear; and an idler shaft supporting the first gear. A method of constructing a camshaft assembly for an internal combustion engine is also provided. The method includes fixing a first gear and a second gear together via a hydraulically driven phasing assembly configured for varying the relative phasing of the second gear with respect to the first gear; and providing the first gear on an idler shaft.

A control device has two modes as control modes of an electric power supply to an electromagnetic solenoid, which are used when a first determining unit determines that a difference between a sensed value of a phase and a target value of the phase exceeds a permissible range. One of the modes is a special mode that is used when a second determining unit determines that the sensed value of the phase reaches a threshold value. Another one of the modes is a normal mode that is used when the second determining unit determines that the sensed value of the phase does not reach the threshold value. In the special mode, the control device controls supply of the electric power to the electromagnetic solenoid in such a manner that an opening degree of an advancing port is larger than the opening degree of the advancing port in the normal mode.