A method for controlling valve timing of an engine may include: classifying control regions; applying a maximum duration to an intake valve and controlling a valve overlap in a first control region; applying the maximum duration to the intake valve and an exhaust valve in a second control region; controlling a manifold absolute pressure (MAP) of an intake manifold to be maintained constant in a third control region; controlling a wide open throttle valve (WOT) and creating a valve overlap by reducing interference of exhaust in a fourth control region; and controlling a wide open throttle valve (WOT) and controlling an intake valve closing timing based on the engine speed. In particular, the control regions are classified by a controller based on an engine load and an engine speed compared with predetermined values, respectively.

A determining unit determines whether the deactivated cylinder is in the activated condition or the deactivated condition. A computing unit computes a synchronize correction amount for synchronizing an activated-side change speed of the activated-side rotational phase and a deactivated-side change speed of the deactivated-side rotational phase with each other, during a deactivated period in which the determining unit determines that the deactivated cylinder is in the deactivated condition. During the deactivated period, a deactivated-side control variable for controlling the deactivated-side rotational phase toward a target phase is corrected with the synchronize correction amount computed by the computing unit.

In starting the engine, if it is determined that large cams are not completely prepared for all driving cams, valve closing timings of all intake valves are changed by driving the VVT so that all of the cylinders have equal in-cylinder filling efficiency. A fuel injection amount of each cylinder is determined by a feedforward control assuming that the large cams are completely prepared for all of the driving cams. When the valve closing timing of all of the intake valves are changed by driving the VVT to equalize the in-cylinder filling efficiencies of all of the cylinders, all of the cylinders have substantially equal in-cylinder air-fuel ratios.

A continuously variable friction drive is used to phase a cam plate attached to the camshaft relative to a sprocket plate driven by the crankshaft. Discs are received within the cavity between the sprocket and cam plate. The discs are free to rotate about an axis of rotation, and is fixed relative to the cam and the sprocket, so that when the sprocket plate rotates, the cam plate is rotated by the discs in the opposite direction. The axis of rotation of the discs can be tilted by an actuator, so that the discs themselves contact the plates at different distances from their axes of rotation, which changes the speed of rotation of one plate relative to the other. When the speed of rotation of the crank and cam differ, the phase angle between the two shafts is changed.

A valve assembly that provides reliable opening and closing valves at specified times despite changing performance characteristics of the valve is disclosed. The valve assembly includes a controllable valve selectively actuatable to control flow of a fluid therethrough, with the controllable valve having a variable valve open/close response time. The valve assembly also includes a plurality of sensors configured to measure current operational parameters of the controllable valve and/or the fluid and a valve controller programmed to process valve timing control instructions generated by an external source, process inputs from the plurality of sensors regarding the measured operational parameters of the controllable valve and/or the fluid, and provide an actuation signal to the controllable valve based on the valve timing control instructions and the inputs from the plurality of sensors, so as to control a timing of an actuation of the controllable valve.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, all intake valves of an engine cylinder may be deactivated, in response to engine load below a threshold, while operating a first exhaust valve coupled to the first exhaust manifold and a second exhaust valve coupled to the second exhaust manifold at different timings. As a result, intake air may be routed from the intake passage, through an exhaust gas recirculation passage coupled between the intake passage and the first exhaust manifold, and into the engine cylinder via the first exhaust valve.

Methods and systems for adjusting exhaust valve timing of an engine are described. In one example, exhaust valve timing of a compression ignition engine is adjusted responsive to a difference between a commanded exhaust valve opening timing and an actual exhaust valve opening timing, the actual exhaust valve opening timing determined from cylinder pressure.

Systems and methods for operating an engine in a variety of different cylinder operating modes are presented. In one example, an actual total number of available cylinder modes is increased in response to a vehicle's suspension setting and road roughness. By increasing the available cylinder modes, the engine may be operated in a higher number of modes where one or more engine cylinders may be deactivated to conserve fuel. The number of cylinder modes is increased during conditions where vehicle occupants may be less likely to object to operating the engine with fewer active cylinders.

The present disclosure provides a system and a method for controlling valve timing of a continuous variable valve duration engine. The method may include: classifying a plurality of control regions depending on an engine speed and an engine load; applying a maximum duration to an intake valve and controlling a valve overlap between the intake valve and an exhaust valve in a first control region; maintaining the maximum duration of the intake valve and applying a maximum duration to the exhaust valve in a second control region; maintaining a manifold absolute pressure (MAP) at a predetermined pressure in a third control region; controlling a throttle valve to be fully opened and generating the valve overlap in a fourth control region; and controlling the throttle valve to be fully opened and controlling intake valve closing (IVC) timing according to the engine speed in a fifth control region.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, all intake valves of an engine cylinder may be deactivated, in response to engine load below a threshold, while operating a first exhaust valve coupled to the first exhaust manifold and a second exhaust valve coupled to the second exhaust manifold at different timings. As a result, intake air may be routed from the intake passage, through an exhaust gas recirculation passage coupled between the intake passage and the first exhaust manifold, and into the engine cylinder via the first exhaust valve.