A novel latch seat for a switching rocker arm assembly used in variable valve actuation (VVA) systems for internal combustion engines. The seat is formed interactively in the assembled switching rocker arm using a novel fixture and press. The press interactively creates a curved dimple of the correct curvature, position and depth while measuring several lash dimensions. Since the latch seat is formed on the assembled rocker arm assembly, the latch seat depth is designed to account for the inaccuracies in the rocker arm assembly parts which create lash. Therefore all of the parts may be made with less precision since the latch seat is sized to compensate for the inaccuracies of all of the parts. The rocker arm assembly parts now may be manufactured to less stringent standards, but result in a rocker arm assembly with same accuracy of rocker arm assemblies manufactured to previous standards.

An apparatus includes a ball plunger post and a valve stem post extending upward from a base, the ball plunger post having a size and a shape of a hydraulic lift adjuster (HLA) of a predefined engine, and the valve stem post having a size and a shape of a valve stem of the predefined engine. The apparatus includes a fixture sized and shaped to receive a switching rocker arm assembly, the switching rocker arm assembly having a first end for pivoting and a second end for latching, and a latch with a latch pin fitting into a latch bore and a latch seat. The apparatus includes a latch rod for positioning within the latch bore to rest upon the latch seat, the latch rod having a hardness higher than that of the latch seat and a same diameter as the latch pin, and adapted for coining the latch seat.

A control technique for an engine having a two-step variable valve lift system includes a controller receiving a pressure in an intake manifold of the engine from a manifold absolute pressure (MAP) sensor and a position of an EGR valve of the engine from an exhaust gas recirculation (EGR) sensor. In response to the controller detecting an upcoming HL-to-LL valve state transition, a set of airflow actuators of the engine is controlled, based on the intake manifold pressure and the EGR valve position, to generate a first torque reserve. In response to generating the first torque reserve, the controller then commands the HL-to-LL transition and depletion of the first torque reserve during the HL-to-LL transition to mitigate torque disturbance associated with this transition.

A modified rocker assembly having an offset end is designed for engine heads having an obstruction preventing use of a symmetric switching rocker arm. The modified rocker assembly has an obstructed side and a non-obstructed side and has an outer structure with a first end, and an inner rocker structure fitting within the outer structure, the inner structure also having a first end. The modified rocker assembly has an axle pivotally connecting the first ends of inner structure to the outer structure, such that the inner structure pivots within the outer structure around the axle. At least one torsion spring on one side of the axle rotationally biases the inner structure relative to the outer structure. The outer structure is offset on the obstructed side as it extends from the second end toward the first end, creating the first offset portion to provide additional clearance on the obstructed side.

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 modified rocker assembly having an offset end is designed for engine heads having an obstruction preventing use of a symmetric switching rocker arm. The modified rocker assembly has an obstructed side and a non-obstructed side and has an outer structure with a first end, and an inner rocker structure fitting within the outer structure, the inner structure also having a first end. The modified rocker assembly has an axle pivotally connecting the first ends of inner structure to the outer structure, such that the inner structure pivots within the outer structure around the axle. At least one torsion spring on one side of the axle rotationally biases the inner structure relative to the outer structure. The outer structure is offset on the obstructed side as it extends from the second end toward the first end, creating the first offset portion to provide additional clearance on the obstructed side.

A control technique for an engine having a two-step variable valve lift system includes a controller receiving a pressure in an intake manifold of the engine from a manifold absolute pressure (MAP) sensor and a position of an EGR valve of the engine from an exhaust gas recirculation (EGR) sensor. In response to the controller detecting an upcoming HL-to-LL valve state transition, a set of airflow actuators of the engine is controlled, based on the intake manifold pressure and the EGR valve position, to generate a first torque reserve. In response to generating the first torque reserve, the controller then commands the HL-to-LL transition and depletion of the first torque reserve during the HL-to-LL transition to mitigate torque disturbance associated with this transition.

A system for diagnosing malfunctions in a variable valve actuation device. The system has a rocker arm assembly with first and second arms attached at a first end and a hydraulically operated latch assembly to secure the first arm to the second arm when latched. The rocker arm assembly pivots upon a hydraulic lash adjuster and includes a source of pressurized fluid connected to a hydraulic valve providing high or low pressure fluid to the hydraulically-operated latch. The latch may be operated by a remote device. A pressure transducer positioned within the hydraulic lash adjuster (HLA) is adapted to create a signal indicating fluid pressure in the HLA. A control unit coupled to the hydraulic valve and the pressure transducer is adapted to sense engine operating parameters, actuate the hydraulic valve, read the signal from the pressure transducer and identify malfunctions of the rocker arm assembly based upon the signal.

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 phaser for adjusting a phase position between a crankshaft and a camshaft of a motor vehicle. The camshaft phaser comprises a stator, a rotor which is rotatable in relation thereto, and working chambers which are formed between the stator and the rotor and each of which are subdivided by a blade of the rotor into a first sub-chamber and a second sub-chamber. For storage of the hydraulic fluid, the camshaft phaser has a reservoir which is connected to the sub-chambers via one non-return valve each, in order that when a negative pressure prevails in one of the sub-chambers, hydraulic fluid is fed from the reservoir to this sub-chamber. The non-return valves are preloaded in such a way that they only open when a pressure within an associated sub-chamber falls below a predetermined negative pressure.