A variable valve operating device for an internal combustion engine includes a cam carrier supported on a camshaft and shifting switching pins that are advanced into and retracted out of shift lead grooves defined in the cam carrier. The shift lead grooves include shift groove side walls having shift groove side wall surfaces from shift starting inflection regions of the cam carrier to shift ending inflection regions thereof. The shift groove side walls include particular shift groove side walls extending from axial positions of the shift starting inflection regions toward shift intermediate regions and also extending from circumferential positions of the shift intermediate regions disposed between the shift starting inflection regions and the shift ending inflection regions toward the shift starting inflection regions. The side walls have slanted outer circumferential surfaces extending from the circumferential positions progressively deeper toward groove bottom surfaces and reaching the shift starting inflection regions.

A retard supply check valve is installed in a retard supply passage and is located on a side of a hydraulic oil controller where a hydraulic oil supply source is placed. The retard supply check valve enables only a flow of hydraulic oil from the hydraulic oil supply source toward a retard chamber. An advance supply check valve is installed in an advance supply passage and is located on the side of the hydraulic oil controller where the hydraulic oil supply source is placed. The advance supply check valve enables only a flow of the hydraulic oil from the hydraulic oil supply source toward an advance chamber.

A camshaft phaser arrangement configured for a concentric camshaft assembly having inner and outer camshafts is provided. The camshaft phaser arrangement includes a first camshaft phaser, a second camshaft phaser, a coupling, and at least one timing wheel connected to at least one of the first or second camshaft phaser. Each of the camshaft phasers is configured to be connected to either the inner or the outer camshaft. The at least one timing wheel defines at least one cutout that is configured to receive at least a portion of the coupling.

A camshaft phaser arrangement configured for a concentric camshaft assembly having inner and outer camshafts is provided. The camshaft phaser arrangement includes a first camshaft phaser, a second camshaft phaser, a coupling, and at least one timing wheel connected to at least one of the first or second camshaft phaser. Each of the camshaft phasers is configured to be connected to either the inner or the outer camshaft. The coupling includes a coupling ring and at least one coupling pin that torsionally connects the first camshaft phaser to the second camshaft phaser. The coupling provides for radial and axial movement between the first camshaft phaser and the second camshaft phaser.

A camshaft phaser arrangement configured for a concentric camshaft assembly having inner and outer camshafts is provided. The camshaft phaser arrangement includes a first camshaft phaser, a second camshaft phaser, and a coupling that non-rotatably connects the first camshaft phaser to the concentric camshaft assembly. Each of the camshaft phasers is configured to be connected to either the inner or the outer camshaft. The coupling accommodates for radial and axial offset between the first camshaft phaser and the second camshaft phaser.

A switched cushion stop for a variable cam timing phaser of a variable cam timing system is disclosed. The cushion stop may be actively controlled by the spool valve or passively controlled.

An inlet check valve for controlling fluid from a supply into a variable cam timing phaser includes a double flapper check valve assembly with an open position and a closed position, which includes a housing having a body forming at least two stoppers, a flapper valve comprising at least two flexible flaps received within the housing and aligned with the at least two stoppers, and a valve seat received within the housing, the valve seat defining openings aligned with the at least two flexible flaps, axially opposite the two stoppers. In another embodiment, the stoppers are on a stopper piece separate from the housing.

A sensor mounting structure for an engine is provided. The sensor mounting structure offers a greater flexibility in mounting a sensor which detects an operation of an actuation member disposed at an inner wall spaced apart from an outer wall of a cylinder head of a valve gear. A sensor mounting structure for an engine includes a valve gear provided at a cylinder head and a sensor detecting an operation of the valve gear. The sensor is mounted on a sensor mounting hole formed at a head inner wall of the cylinder head covered with a cylinder head cover.

An engine oil passage structure for an engine contributing to downsizing the engine and achieving protection of an oil passage against external forces is provided. Provided is an oil passage structure for an engine installed in a small vehicle, the engine including an engine body formed of a crankcase and a cylinder block and a cylinder head stacked inclined vehicle frontward on the crankcase, the crankcase, the cylinder block, and the cylinder head being integrally fastened. The oil passage structure includes, near a bent part formed by a case front wall of the crankcase and a cylinder front wall of the cylinder block forming a valley part by an obtuse angle, a right-left direction oil passage extending in a right-left direction along the valley part.

Using existing phaser control valve and a solenoid to create a pumping chamber which provides enough oil pressure to disengage a locking pin at all conditions.