Methods and systems are provided for reducing hydrocarbon emissions from an engine. In one example, a method may include adjusting timing profiles of a first and a second exhaust valve to selectively allow pneumatic communication between a cylinder and exhaust ports of an exhaust manifold during an engine cold start.

Methods and systems are provided for reducing hydrocarbon emissions from an engine. In one example, a method may include adjusting timing profiles of a first and a second exhaust valve to selectively allow pneumatic communication between a cylinder and exhaust ports of an exhaust manifold during an engine cold start.

Methods and systems are provided for increasing EGR delivered to an engine. In one example, a method may include determining an EVO timing set point and an external EGR setpoint in parallel, based on an inverse model. The EVO timing may be adjusted based on a combination of the EVO timing setpoint and an EGR cylinder balancing feedback loop, thereby varying internal EGR to the engine to supplement external EGR.

A valvetrain for a type II engine comprises a valve bridge, a switching rocker arm, a center capsule, a first auxiliary rocker arm, and a first auxiliary capsule. The selectively switching rocker arm is configured to switch configurations to transfer a first valve actuation profile from a first overhead cam lobe to the valve bridge center point and to transfer a second valve actuation profile from a second overhead cam lobe to the center point. The center capsule is configured to switch between an active state and a lost motion state. The first auxiliary rocker arm is configured to transfer a first auxiliary valve actuation profile from a third overhead cam lobe to the valve bridge first valve mounting area. The valvetrain can further comprise a second auxiliary rocker arm and a second auxiliary capsule.

A method for operating an engine during a fuel cut-off mode is disclosed. The method may adjust exhaust valve opening timing and exhaust valve lift of one or more cylinders to heat air flowing through the one or more cylinders so that a temperature of an after treatment device may be maintained or increased.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, a method may include supplying air to an exhaust system at a location downstream of an emissions control device via the first exhaust manifold, the air not having participated in combustion in the engine, the first exhaust manifold in fluidic communication with a first exhaust valve of a cylinder and an intake manifold, the cylinder including a second exhaust valve in fluidic communication with the second exhaust manifold. The method may further include adjusting an amount of fuel injected to the engine in response to output of a first oxygen sensor, the first oxygen sensor positioned in the exhaust system upstream of the emissions control device.

A combined dedicated braking and EEVO lost motion valve actuation systems for internal combustion engines provide subsystems for braking events and EEVO events on one or more cylinders. Various control strategies may utilize braking and EEVO capabilities to module one or more engine parameters, including aftertreatment temperature and engine load.

A valvetrain for a type II engine comprises a valve bridge, a switching rocker arm, a center capsule, a first auxiliary rocker arm, and a first auxiliary capsule. The selectively switching rocker arm is configured to switch configurations to transfer a first valve actuation profile from a first overhead cam lobe to the valve bridge center point and to transfer a second valve actuation profile from a second overhead cam lobe to the center point. The center capsule is configured to switch between an active state and a lost motion state. The first auxiliary rocker arm is configured to transfer a first auxiliary valve actuation profile from a third overhead cam lobe to the valve bridge first valve mounting area. The valvetrain can further comprise a second auxiliary rocker arm and a second auxiliary capsule.

A compression-release brake system for operating an exhaust valve of an engine during an engine braking operation. The compression-release brake system comprises a self-contained compression brake control module (CBCM) operatively coupled to the exhaust valve for controlling a lift and a phase angle thereof. The CBCM includes a casing defining an actuator cavity, a actuation piston disposed outside the casing so as to define an actuation piston cavity between the casing and the actuation piston, and a check valve provided between the actuation piston cavity and a compression brake actuator disposed in the actuator cavity. The actuation piston reciprocates relative to the casing. The compression brake actuator includes an actuator element and a biasing spring. The actuator element selectively engages the check valve when deactivated so as to unlock the actuation piston cavity and disengages from the check valve when activated so as to lock the actuation piston cavity.

A method for operating a reciprocating piston internal combustion engine in an engine braking mode includes moving an outlet valve of a first cylinder for a first time into a closed position, subsequently for a first time into an open position, subsequently in a direction of the closed position, and subsequently for a second time into the open position. The outlet valve is held open during the moving in the direction of the closed position for such a long time that the first cylinder is filled with gas which flows via an outlet duct out of a second cylinder. The outlet valve is moved, during the moving in the direction of the closed position, into an intermediate position which lies between the open position and the closed position, where from the intermediate position the outlet valve is moved for the second time into the open position.