A control apparatus is applicable to an internal combustion engine having an exhaust passage arranged with an NSR catalyst and an SCR catalyst, wherein when it is necessary to decrease NH.sub.3 adsorbed to the SCR catalyst, then an air-fuel ratio of an air-fuel mixture to be combusted in the internal combustion engine is controlled to a predetermined lean air-fuel ratio which is higher than a theoretical air-fuel ratio if a temperature of the SCR catalyst is not less than a lower limit temperature at which NH.sub.3 can be oxidized, while the air-fuel ratio of the air-fuel mixture to be combusted in the internal combustion engine is controlled to a predetermined weak lean air-fuel ratio which is lower than the predetermined lean air-fuel ratio and which is higher than the theoretical air-fuel ratio if the temperature of the SCR catalyst is less than the lower limit temperature.

In a lean-burn engine equipped with a turbocharger, a responsiveness of a supercharging pressure in a lean region is enhanced by control of a valve timing of an exhaust valve while a combustion state is restrained from varying. A variable valve mechanism that can change an opening timing of the exhaust valve while keeping a closing timing of the exhaust valve constant, is included in the lean-burn engine. When a target operation point is located in the lean region, and when an actual supercharging pressure is lower than a target supercharging pressure, supercharging pressure increasing control that advances the opening timing while keeping the closing timing constant is executed by operating the variable valve mechanism.

A method for heating an exhaust gas aftertreatment component in an exhaust system of an internal combustion engine. At the combustion chamber, a fuel injector for injecting a fuel into the combustion chamber and a spark plug for igniting a flammable fuel-air mixture are arranged. The internal combustion engine has a valve lift curve switching mechanism, which allows for a shift and/or change of the opening times of the exhaust valve. The method includes: intake of fresh air into the combustion chamber, injection of a fuel into the combustion chamber, ignition of an ignitable fuel-air mixture in the combustion chamber when the piston is in a range of 10? KW to 30? KW after the upper ignition dead point, and opening of the exhaust valve when the piston is in a range of 55? KW to 95? KW after the upper ignition dead point.

An internal combustion engine includes a cylinder including a piston connected to a rotatable crankshaft, an air guide arranged to guide an air flow to the cylinder an adjustable air flow restriction element arranged to restrict the How through the air guide, an exhaust guide being arranged to guide a gas flow from the cylinder, an adjustable exhaust flow restriction element arranged to restrict the flow through the exhaust guide, an exhaust valve arranged to control a communication between the cylinder and the exhaust guide, and an exhaust valve actuation assembly for actuating the exhaust valve so as to perform in each of a plurality of cycles of the cylinder an exhaust valve actuation sequence, wherein the exhaust valve actuation assembly is adapted to control the commencement of the exhaust valve actuation sequence to occur selectively at any crankshaft angle within a non-zero crankshaft angle interval.

Methods and systems are provided to control exhaust energy delivered to a turbine of a turbine-generator coupled to a split exhaust engine system in order to limit turbine over-speed conditions and/or reduce generator vibration or reduce component over-heating conditions. In one example, a method may comprise in response to turbine speed greater than a threshold speed, selectively deactivating a first exhaust valve of one or more cylinders of a first and second cylinder group.

Systems and methods for improving detection and mitigation of engine misfire are presented. Engine misfire is determined by sampling exhaust pressure of a cylinder only during a time when an exhaust valve of the cylinder is in an open state. If misfire is indicated, an actuator is adjusted to reduce the possibility of misfire during a subsequent cylinder cycle.

A control unit for an internal combustion engine is configured for suppressing knocking phenomenon with reduction of overlap, while maintaining an opening timing of an exhaust valve at the time of low-rotation, high-load state. A valve opening/closing timing control apparatus includes a phase adjustment mechanism configured to vary a relative rotational phase between a driving side rotary body rotatable in synchronism with a crankshaft of the internal combustion engine and a driven side rotary body rotatable together with an exhaust cam shaft. After an opening timing of the exhaust valve, an advancing operation is effected for displacing the relative rotational phase in the advancing direction relative to the opening timing.

A method to control a four-stroke combustion engine, comprising at least one cylinder; a piston arranged in each cylinder; at least one inlet valve arranged in each cylinder which is connected with an inlet system; at least one first camshaft which controls each inlet valve; at least one exhaust valve arranged in each cylinder which is connected with an exhaust system; at least one second camshaft which controls each exhaust valve; and a crankshaft which controls each camshaft. At least one phase-shifting device is arranged between the crankshaft and the second camshaft, to phase-shift the second camshaft in relation to the crankshaft to a state, where the exhaust valve is controlled in such a way, that it is opened during the expansion stroke of the engine and closed during the exhaust stroke of the engine, to achieve engine braking through compression in the cylinders during the exhaust stroke.

An internal combustion engine system includes an engine with a plurality of pistons housed in respective ones of a plurality of cylinders, an air intake system to provide air to the plurality of cylinders through respective ones of a plurality of intake valves, an exhaust system to release exhaust gas from the plurality of cylinders through respective one of a plurality of exhaust valves, an aftertreatment system to treat exhaust emission from the engine, and a controller coupled to at least one sensor and configured to control a cam phaser for thermal management of the aftertreatment system.

A stop control device for an internal combustion engine is structured that stops the engine in a state suitable for starting and that does not cause a crank angle to change after the engine is stopped. A four-cycle internal combustion engine includes an electric valve opening and closing timing control device that sets an opening and closing timing of either or both of an intake valve and an exhaust valve. Stop control of stopping the internal combustion engine is performed when a stop signal for stopping the internal combustion engine is acquired, and post-stop phase control of displacing the opening and closing timing of the valve opening and closing timing control device in either an advancing direction or a retarding direction is performed after the internal combustion engine is stopped by the stop control.