An engine control device is provided, which includes an engine body where a cylinder is formed, an exhaust passage through which exhaust gas discharged from the engine body circulates, a NO.sub.x sensor disposed in the exhaust passage and configured to detect a concentration of NO.sub.x in the exhaust gas, an injector configured to change an air-fuel ratio inside the cylinder, an in-cylinder temperature changer configured to change a temperature inside the cylinder, and a controller configured to control the injector and the exhaust shutter valve. The controller controls the injector based on a detection value of the NO.sub.x sensor to variably set the air-fuel ratio inside the cylinder, and when a particular condition that the air-fuel ratio inside the cylinder is leaner than a preset upper limit is satisfied, and causes the in-cylinder temperature changer to raise the temperature inside the cylinder.

A fuel injection control system may include a variable exhaust valve mechanism configured to primarily open an exhaust valve directly before an intake stroke in which an intake valve is opened and to secondarily open the exhaust valve during the intake stroke such that valve overlap occurs; an exhaust injector provided at an exhaust side to inject fuel; and a controller for controlling the exhaust injector such that fuel is injected through the exhaust injector before the exhaust valve is opened secondarily before or during the intake stroke.

A method for controlling intake and exhaust valves of an engine may include: determining, by a controller, a target opening duration of the intake and exhaust valves based on an engine load and an engine speed; modifying, by an intake continuous variable valve duration (CVVD) device and by an exhaust CVVD device, current opening and closing timings of the intake valve and/or exhaust valve based on the target opening duration of the valves; and advancing or retarding, by the intake and/or exhaust CVVD devices, the current opening timing of the intake and exhaust valves while simultaneously retarding or advancing the current closing timing of the intake and exhaust valve by a predetermined value based on the target opening duration.

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.

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 variable valve actuation mechanism to provide variable engine braking for thermal management.

Methods and systems are provided for a dual function imaging device. In one example, a method may comprise imaging exhaust gas outside of a reverse engine condition via the imaging device. The imaging device may image a surrounding area during the reverse engine condition.

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 first set of exhaust valves coupled to the first exhaust manifold may be operated at a different timing than a second set of exhaust valves coupled to the second exhaust manifold. Further, a position of a first valve positioned in a first passage coupled between the intake passage and the first exhaust manifold and/or a timing of the first set of exhaust valves may be diagnosed based on an output of a pressure sensor positioned in the first exhaust manifold.

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 flow of exhaust (e.g., exhaust gas recirculation) from engine cylinders to the intake passage, upstream of a compressor, via an exhaust gas recirculation (EGR) passage and the first exhaust manifold may be adjusted by adjusting a timing of a first set of cylinder exhaust valves coupled to the first exhaust manifold. Additionally, the first set of cylinder exhaust valves open at a different time than a second set of cylinder exhaust valves coupled to the exhaust passage.

A method of heating a catalytic converter of an internal combustion engine, wherein the method comprises the steps of: igniting the gas charge in one of the cylinders in a range from 10? CA before ignition top dead center to 20? CA after ignition top dead center; and opening the exhaust valve of the cylinder exhaust of the cylinder in a range from 30? CA to 55? CA after ignition top dead center. The method allows the catalytic converter of the internal combustion engine to quickly reach operating temperature and thus contributes to the reduction of pollutant emissions. An internal combustion engine is also provided that is designed to carry out the method of the invention for heating a catalytic converter.

A variable valve device includes: a cam having profiles with different exhaust valve opening and closing timings, a rocker arm, and a socket having a piston. In particular, an exhaust valve is connected to a valve bridge and the piston vertically moves by oil pressure supplied to an inside of the socket. When the piston protrudes downward from the socket, the rocker arm and the cam come into contact with each other, and the exhaust valve is opened and closed by the cam profiles.