Abstract: A method of controlling an engine is provided. At least one operating parameter of the engine is sensed. The engine is operated in a first mode in response to the sensed operating parameter being at one of a predetermined first set of conditions. In the first mode, a cam assembly moves an intake valve from a first position when a piston starts an intake stroke and the cam assembly returns the intake valve to the first position when the piston completes the intake stroke. The engine is operated in a second mode in response to the sensed operating parameter being at one of a predetermined second set of conditions. In the second mode, the cam assembly moves the intake valve from the first position when the piston starts an intake stroke and an actuator prevents the intake valve from returning to the first position in response to the cam assembly.

Abstract: A method of controlling a variable valve actuation system is provided. A cam assembly is operated to move an intake valve between a first position where the intake valve blocks a flow of fluid and a second position where the intake valve allows a flow of fluid. At least one operating parameter of the engine is sensed. A valve actuation period is determined based on the at least one operating parameter. A valve actuator is engaged with the intake valve to prevent the intake valve from returning to the first position in response to operation of the cam assembly. The valve actuator is released to allow the intake valve to return to the first position at the end of the determined valve actuation period.

Abstract: An engine valve actuation system is provided. The system includes an engine valve moveable between a closed position and an open position. A spring is operatively connected to the engine valve to bias the engine valve towards the closed position. An actuator is operatively connected to the engine valve and is operable to selectively engage the engine valve to prevent the engine valve from returning to the closed position and to release the engine valve to allow the engine valve to return to the closed position. A sensor is configured to provide information related to the operation of the actuator. A controller is configured to transmit a signal to the actuator to engage the engine valve to prevent the engine valve from returning to the closed position and to release the engine valve to the allow the engine valve to return to the closed position.

Abstract: An airflow system for an engine includes a first turbine coupled with a first compressor and a second turbine coupled with a second compressor. The first turbine receives exhaust from the engine, and the first compressor supplies compressed air to the engine. The second compressor compresses air from atmosphere. A first conduit fluidly couples the first and second turbines, and a second conduit fluidly couples the first and second compressors. A wastegate valve is fluidly coupled with the exhaust manifold and movable between a first position in which exhaust fluid is allowed to bypass the first turbine and a second position in which fluid is restricted from bypassing. The airflow system includes a third conduit fluidly coupling the second compressor and the wastegate valve. The wastegate valve moves to the first position when compressed air in the third conduit has at least a predetermined pressure.

Abstract: An engine valve actuator providing Miller cycle benefits and a method of operating an engine valve actuator are disclosed. The valve actuator employs a first force to hold an exhaust valve of the engine open during an exhaust stroke and a second, stronger force to hold the exhaust valve open during a compression stroke. The valve actuator may be operated using pressurized fluid adapted to extend an actuator piston through a cylinder. The first force may be derived by a mechanically driven actuator, while the second force may be derived from a high pressure rail of the engine. A low pressure source of the engine may be used to fill the actuator cylinder, with the high pressure rail only being placed into fluid communication with the cylinder when desired. A control valve may be employed to direct either the low pressure or high pressure fluid to the valve actuator cylinder.