A method for ascertaining a valve position of a valve of an internal combustion engine having a multiplicity of valves. The method includes illuminating a combustion chamber of the internal combustion engine, detecting light emerging from the illuminated combustion chamber on a side, averted from the combustion chamber, of the valve for ascertainment, and determining the valve position of the valve for ascertainment by way of the detected light.

Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

A valve actuation system is disclosed for an engine. The valve actuation system may have a variable valve actuator that is configured to engage a rocker arm and hold the valve at an open position regardless of motion of a cam lobe. The variable valve actuator may have a housing forming a chamber, a plunger disposed in the chamber, a control valve movable to control a flow of fluid into the chamber, and a relief valve configured to automatically open and release fluid from the housing when a pressure inside the chamber is below a predetermined pressure. The valve actuation system may further have a controller configured to cycle the control valve prior to start-up of the engine and to selectively move the control valve after start-up.

A method for heating a sliding camshaft actuator at cold engine start wherein the sliding camshaft actuator includes at least one magnetic field generating coil having a core, a piston armature disposed in the core of the at least one magnetic field generating coil, a magnet in mechanical communication with the piston armature, and an actuator pin in mechanical communication with the magnet. The method includes detecting a cold engine start condition and reversing an energizing voltage on the at least one magnetic field generating coil when the outside temperature is below a predetermined temperature threshold. The reverse energizing voltage on the at least one magnetic field generating coil is maintained for a predetermined period of time to heat the piston armature, the magnet, and the actuator pin.

Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

The disclosure relates to a camshaft adjustment system comprising a hydraulic camshaft adjuster having a stator and a rotor forming at least one working chamber. The at least one working chamber is divided into a first sub-chamber and a second sub-chamber. The sub-chambers interact with a control valve controllable via a first actuator. When the first sub-chamber undergoes a volume increase, the rotor is displaced into a late position relative to the stator, and when the second sub-chamber undergoes a volume increase, the rotor is displaced into an early position relative to the stator. A second actuator actuated independently of the first actuator is provided. In order to release the camshaft adjuster from the late position when in an operating state, a ram of the second actuator displaces a locking pin of a late-locking device of the camshaft adjuster out of its position that locks the late position.

A method according to the invention for controlling an internal combustion engine having a camshaft whose phase with respect to a crankshaft can be adjusted by means of an electric adjustment device, and a control device comprises the steps S1 to S3, wherein in step S1 a stop request is output from the control device to the electric adjustment device. Subsequently, in step S2 a manipulated variable in the form of a pulse duty factor is output from the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque. In step S3, the direction of rotation of the camshaft is monitored, wherein in step S4, when a reversal of the direction of rotation of the camshaft is detected, an intensity level of this reversal of the direction of rotation is calculated by determining a rotational speed gradient. Furthermore, in a step S5 the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal of the direction of rotation on the position of the camshaft is compensated.

A method for heating a sliding camshaft actuator at cold engine start wherein the sliding camshaft actuator includes at least one magnetic field generating coil having a core, a piston armature disposed in the core of the magnetic field generating coil, a magnet in mechanical communication with the piston armature, and an actuator pin in mechanical communication with the magnet. The method includes detecting a cold engine start condition and reversing an energizing voltage on the magnetic field generating coil when the outside temperature is below a predetermined temperature threshold. The reverse energizing voltage on the magnetic field generating coil is maintained for a predetermined period of time to heat the piston armature, the magnet, and the actuator pin.

A method of controlling intake and exhaust cam phase in an internal combustion engine includes sensing an engine speed and an engine load of the internal combustion engine, sensing or estimating a wall temperature of a cylinder of the internal combustion engine, utilizing the engine speed and the engine load in one or more lookup tables based on the cylinder wall temperature to determine intake phaser constraint values and exhaust phaser constraint values for cold operation of the internal combustion engine, and transitioning the intake phaser constraint values and the exhaust phaser constraint values for cold operation to intake phaser constraint values and exhaust phaser constraint values based on one or more lookup tables for normal hot operation of the internal combustion engine.

A valve actuation system is disclosed for an engine. The valve actuation system may have a variable valve actuator that is configured to engage a rocker arm and hold the valve at an open position regardless of motion of a cam lobe. The variable valve actuator may have a housing forming a chamber, a plunger disposed in the chamber, a control valve movable to control a flow of fluid into the chamber, and a relief valve configured to automatically open and release fluid from the housing when a pressure inside the chamber is below a predetermined pressure. The valve actuation system may further have a controller configured to cycle the control valve prior to start-up of the engine and to selectively move the control valve after start-up.