A rocker arm assembly can comprise a main rocker arm and a latch assembly. A latching arm can control the latch assembly and thereby control the extent to which a secondary rocker arm acts on the main rocker arm. The main rocker arm can comprise a main body configured to rotate around a rocker shaft, a valve end extending from the main body, a reaction end extending from the main body, and a latch bore. A bias pin can extend from the main body. The latch assembly can be configured to selectively rotate in the latch bore. The latch assembly can comprise a first latch end comprising a switch plate configured to receive actuation force on a first side and to receive bias force from the bias pin on a second side. A second latch end can comprise a first latch seat and a second latch seat.

A castellation assembly comprises a lost motion spring assembly, an upper castellation piece, and a lower castellation piece. A spring hat comprises a crown, a pin hole through the crown, and a brim. A lost motion spring is seated against the spring hat.

Upper castellation piece comprises a tubular body, an upper inner rim adjoining the brim, and upper castellation teeth. Lower castellation piece comprises a spring post extending up from a castellation body, the spring post passing through the lost motion spring, and through the pin hole. Lower castellation teeth extend from the castellation body. The lost motion spring is biased against the castellation body to lift the upper inner rim by the brim. A lash screw can house the spring post so that the spring post terminates inside the lash screw. A rocker arm is an example of a castellation assembly installation.

A valve actuation system comprises at least one main rocker arm operatively connected to a first engine valve, the at least one main rocker arm configured to receive at least main valve actuation motions. A second rocker arm is operatively connected to a second engine valve, the second rocker arm being configured to receive first auxiliary valve actuation motions. The second rocker arm further comprising a hydraulically-controlled first actuator that can selectively couple or decouple the second rocker arm and the second engine valve thereby permitting or preventing conveyance of the first auxiliary valve actuation motions from the second rocker arm to the second engine valve. A one-way coupling mechanism disposed between the at least one main rocker arm and the second rocker arm permits valve actuation motions to be transferred from the at least one main rocker arm to the second rocker arm, but not vice versa.

Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, valves of a cylinder are deactivated in a closed state in response to an indication of degradation of a valve of the cylinder. Further, fuel flow to the cylinder may be stopped via ceasing to inject fuel to the cylinder.

A valvetrain for an internal combustion engine includes a camshaft, an electromagnetic latch assembly, a rocker shaft, and a rocker arm assembly. The rocker arm assembly may include a cam follower configured to engage a cam mounted on the camshaft as the camshaft rotates and a rocker arm configured to rotate on the rocker shaft. The electromagnetic latch assembly may include a pin translatable between a first position and a second position and an electromagnet that causes the pin to actuate. The movement of the pin may provide mode switching for a switching rocker arm, a cylinder deactivating rocker arm, or an engine brake rocker arm. The electromagnet is powered by a circuit that passes through the rocker shaft. The electromagnet may be mounted to the rocker shaft. Running the circuit through the rocker shaft allows the electromagnet to be powered with wiring that remains stationary.

Methods and systems are provided for providing secondary air to an exhaust system during catalyst warm-up. In one example, a method may include, during a cold start condition, operating an engine with a first number of cylinders unfired and a remaining number of cylinders fired during an engine cycle, opening an intake valve of an unfired cylinder of the first number of cylinders during an expansion stroke of the unfired cylinder, and opening an exhaust valve of the unfired cylinder during a compression stroke of the unfired cylinder. In this way, the unfired cylinders may provide the secondary air to the exhaust system during a stroke that increases mixing of the secondary air with burned exhaust gas from fired cylinders, thus increasing exotherm production in the exhaust system to increase a temperature of the catalyst.

A system for monitoring operation of an internal combustion engine having a rocker arm assembly for actuating an engine valve is disclosed. The rocker arm assembly includes a first arm with a first end and a second end, at least one slider pad connected to the first arm near the second end of the first arm, a second arm also having a first end pivotally connected near the first end of the first arm along a pivot axle, a latch that when latched secures the first arm relative to the second arm in a latched mode, and when unlatched allows the first arm to move relative to the second arm in an unlatched mode. The system also employs a sensor attached to one of the arms that can detect when the arms are moving relative to each other, and adapted to provide a signal indicating the detected movement.

A type II valve train assembly that selectively opens first and second intake valves and first and second exhaust valves is provided. The valve train assembly includes an intake rocker arm assembly and an exhaust rocker arm assembly. The valve train assembly is configurable for operation in any combination of activated and deactivated states of engine braking and cylinder deactivation. The exhaust rocker arm assembly includes a first exhaust rocker arm, a second exhaust rocker arm and an engine brake exhaust rocker arm. A first exhaust HLA is associated with the first exhaust rocker arm. A second exhaust HLA is associated with the second exhaust valve. An exhaust actuation assembly selectively actuates to alter travel of the first and second exhaust HLA's to change a state of cylinder deactivation between activated and deactivated.

A classifier capable of predicting if cylinder valves of an engine commanded to activate or deactivate failed to activate or deactivate respectively. In various embodiments, the classifier can be binary or multi-class Logistic Regression, or a Multi-Layer Perceptron (MLP) classifier. The variable displacement engine can operate in cooperation with a variable displacement engine using cylinder deactivation (CDA) or skip fire, including dynamic skip fire and/or multi-level skip fire.

Systems and methods for preparing an engine for a cold start are described. In one example, the air is injected into one or more pre-chambers of engine cylinders in response to an engine start request so that one or more cylinders may be heated before the engine is started. The engine may or may not be rotated while air is being injected to pre-chambers of engine cylinders.