A method for controlling intake and exhaust valves of an engine may include: determining, by a controller, a target opening duration of the intake and exhaust valves based on an engine load and an engine speed; modifying, by an intake continuous variable valve duration (CVVD) device and by an exhaust CVVD device, current opening and closing timings of the intake valve and/or exhaust valve based on the target opening duration of the valves; and advancing or retarding, by the intake and/or exhaust CVVD devices, the current opening timing of the intake and exhaust valves while simultaneously retarding or advancing the current closing timing of the intake and exhaust valve by a predetermined value based on the target opening duration.

A method for controlling intake and exhaust valves of an engine includes: Controlling opening and closing timings of the intake and exhaust valves by an intake continuous variable valve timing (CVVT) device and an exhaust CVVT devices; determining, by a controller, target intake and exhaust opening durations of the intake and exhaust valves, and target opening and closing timings of the valves based on an engine load and an engine speed; modifying current intake and exhaust opening durations based on the target opening durations via an intake continuous variable valve duration (CVVD) device and an exhaust CVVD device; adjusting opening or closing timings of the valves to the target opening or closing timings of the valves while maintaining the modified opening durations of the valves.

It is intended to, when abnormality in either one of two rotation detection sections with different detection frequencies occurs, quickly and highly accurately detect the abnormality to favorably deal with abnormality occurring during low engine rotation. It is determined that abnormality is present in the rotation phase detection section, when an absolute value of difference between an actual VTC angle detected by a rotation phase detection section and an integrated value of a VTC change angle detected by motor rotation sensor 201 with the higher detection frequency than the frequency of detection of the actual VTC angle by the rotation phase detection section is equal to or greater than a predetermined value.

A variable valve system including a crank angle sensor that measures a rotation angle of a crankshaft, a cam angle sensor that measures a rotation angle of a camshaft coupled to the crankshaft and which opens and closes valves, and a controller that controls the internal combustion engine. At least one of the crank angle sensor or the cam angle sensor is configured as an absolute angle sensor that measures an absolute rotation angle and outputs a voltage signal corresponding to this rotation angle. The controller is configured to perform a correction operation that corrects a rotation angle value calculated based on the voltage signal.

Systems and methods for operating exhaust valves of an internal combustion engine with poppet exhaust valves are described. The systems and methods provide for locking exhaust valves in a closed state when the exhaust valves are in mechanical communication with a base circle of a camshaft lobe. Locking the exhaust valves in a closed state may reduce the possibility of exhaust pressures opening the exhaust valves at times they may not be desired to be open.

A camshaft-drive tensioner system is disclosed for an internal combustion engine having a camshaft-drive element. The camshaft-drive tensioner system includes a tensioner configured to be energized by a pressurized fluid in order to apply a force to the camshaft-drive element. The camshaft-drive tensioner system also includes a fluid pump configured to supply the pressurized fluid. The camshaft-drive tensioner system additionally includes a controller configured to regulate either volume or pressure of the fluid supplied to the tensioner by the fluid pump to thereby selectively vary the force applied to the camshaft-drive element. An internal combustion engine having such a camshaft-drive tensioner system and a method of selectively varying a force applied to the camshaft-drive element are also disclosed.

The present invention relates to a control device and a control method for a variable valve timing mechanism that changes a valve timing by adjusting a rotational speed of a motor. The control device detects a phase angle RA1 based on an output of a crank angle sensor and an output of a cam angle sensor and calculates a change amount RA of a rotational phase based on a difference between a rotation amount of a sprocket and a rotation amount of the motor. The control device stops calculating change amount RA when a failure occurs in a motor rotation angle sensor. When a failure occurs in one of the crank angle sensor or the cam angle sensor, the control device stops calculating phase angle RA1 and calculates change amount RA using a normal one of the sensors and the motor rotation angle sensor.

Function of a compression release brake system of a compression ignited engine with a plurality of cylinders in a motor vehicle is checked by driving a crank shaft of the engine to rotate at a constant speed without injection of fuel into the cylinders while for each cylinder, for the compression release brake system in an inactive state and then in an active state, measuring the torque to be applied for maintaining said speed in a position of said crank shaft where the torque would be influenced by the behavior of that cylinder by a correctly functioning action of said compression release brake system in an active state. The torque values obtained for each cylinder for the compression release brake system in inactive and active state are compared, and the function of the compression release brake system for each individual cylinder of the engine is determined based on the comparison.

A variable valve apparatus may include a crank position sensor sensing a position of a crank shaft, a plurality of valves selectively opening or closing a combustion chamber in a cylinder, a hydraulic pump supplying a hydraulic pressure or a hydraulic flow, servo valves controlling the hydraulic pressure or hydraulic flow supplied from the hydraulic pump according to the position of the crank position, sensed by the crank position sensor, actuators operating the valves by the hydraulic pressure or hydraulic flow supplied from the servo valves, and a controlling outputting a control signal that controls an open amount and open time of the servo valves according to a position of the crank shaft.

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.