A control system for internal combustion engines having four valves per cylinder. An inlet valve and an exhaust valve are controlled by a basic camshaft. Another inlet valve and another exhaust valve are controlled by a control camshaft. The two camshafts are connected to a crankshaft and engine torque is managed by an electronic control unit. The system comprises a motor/generator unit, connected to the control camshaft; a differential, connected to the crankshaft and to the control camshaft; a control shaft, connected to the differential; an actuator, connected to the control shaft; a one-way restrictor valve connected to a shut-off valve and to the actuator; an oil circuit, connected to the actuator by means of the shut-off valve and a control solenoid that acts on the shut-off valve.

Methods and systems are provided for providing exhaust gas recirculation to a naturally aspirated internal combustion engine. In one example, exhaust gas is recirculated to an engine intake via a dedicated scavenging manifold and a scavenging exhaust valve. The exhaust gas and fresh air that has not participated in combustion may be recirculated to engine cylinders even at high engine loads since the exhaust gas and fresh air is returned to the engine air intake at a pressure greater than atmospheric pressure.

Methods and systems are provided for determining a dilution of recirculated gases, including blowthrough air, combusted exhaust gas, and fuel vapor, in a split exhaust engine. In one example, the dilution rate may be calculated using a steady state model based on temperature measurements from an intake region of the engine. The steady state model may be further used in combination with a feedforward model adapted to estimate engine dilution during engine transients as a correction factor.

A supercharged internal combustion engine has cylinder groups with plural cylinders and plural exhaust gas turbochargers. Exhaust gas can be fed to at least one first exhaust gas turbocharger from first outlet valves of the cylinders of the first and second cylinder groups via at least one first exhaust manifold. Exhaust gas can be fed to at least one second exhaust gas turbocharger from second outlet valves of cylinders of the first and second cylinder groups via a second exhaust manifold. At low rotational speeds and/or in part load and/or non-steady state operation, exhaust gas can be fed via the first exhaust manifolds that are connected to the first outlet valves per cylinder group to a turbine of the first exhaust gas turbocharger in flows that can be divided in the inflow region of the turbine, while the second exhaust gas turbocharger is inactive.

An internal combustion engine includes combustion chambers, each having a first intake port, and first and second exhaust ports. An intake manifold is connected to the first intake port of each combustion chamber, a main pressure booster upstream of the intake manifold. An exhaust discharge arrangement includes a main exhaust manifold connected to the first exhaust port of each combustion chamber, the exhaust discharge arrangement connected to the second exhaust port of a first subset combustion chambers, and an exhaust recirculation manifold connected to the second exhaust port of a second subset combustion chambers and connected to an upstream side of the main pressure booster. The engine operates in high load and low load modes, which vary how the engine evacuates the exhaust gas of the second subset combustion chambers to the exhaust recirculation manifold. A related method is also disclosed.

Methods and systems are provided for reducing engine compression torque when an engine having a split exhaust system is spun unfueled. In one example, a method may include maintaining closed a blowdown exhaust valve of a cylinder, the blowdown exhaust valve coupled to a first exhaust manifold that directs gases from the cylinder to a catalyst, and opening a scavenge exhaust valve of the cylinder, the scavenge exhaust valve coupled to a second exhaust manifold that directs gases from the cylinder to an exhaust gas recirculation system. In this way, compression of gases within they cylinder is reduced while gas flow to the catalyst is prevented.

An internal combustion engine is configured to periodically open and close combustion chamber exhaust valves of the engine such that one exhaust valve is held open longer than another exhaust valve and/or one exhaust valve opens before another exhaust valve relative to top dead center. The resulting differential exhaust valve timing can at least partially compensate for different swallowing capacities of the scrolls of a twin-scroll turbine.

Disclosed is a control device for a multi-cylinder engine having a combustion chamber (19) to which an intake port (16) and an exhaust port (17) are connected. The control device comprises: an intake-side variable valve operating mechanism (71) for controlling a lift timing of two intake valves (21a, 21b) of the intake port (16); an exhaust-side variable valve operating mechanism (72) for controlling a lift timing of an exhaust valve (22a); and an exhaust-side valve operating mechanism (73) for driving an exhaust valve (22b) at a fixed timing. The control device is operable, when executing cylinder deactivation in a low engine load and low engine speed operating range, to cause the exhaust-side variable valve operating mechanism (72) to open the exhaust valve (22a) during downward movement of a piston (14) in a cylinder (18) being subjected to the cylinder deactivation.

Methods and systems of recirculating exhaust gas in internal combustion engines are disclosed. An internal combustion engine includes a set of cylinders, an intake system disposed in fluid providing communication with the set of cylinders, an exhaust system disposed in fluid exchanging communication with the set of cylinders, and a controller. In response to a detected recirculation condition, the controller prevents fluid communication between the intake system and a subset of the set of cylinders and recirculates exhaust gas between the subset of the set of cylinders and the exhaust system.

A method for advancing valve actuation during low load or idle diesel engine conditions to promote aftertreatment heat up comprises switching a cam phaser from a nominal lift position to an advance lift position to open an affiliated valve before nominal. Valve lift is actuated via the cam phaser. The valve is lowered towards nominal closure, and valve closure is interrupted by actuating a latch phaser. Valve closure is extended beyond nominal valve closure.