Methods, devices, controllers, and algorithms are described for operating an internal combustion engine wherein at least some firing opportunities utilize low temperature gasoline combustion (LTGC). Other firing opportunities may be skipped or utilize some other type of combustion, such as spark ignition. The nature of any particular firing opportunity is dynamically determined during engine operation, often on a firing opportunity by firing opportunity basis. Firings that utilize LTGC produce little, if any, nitrous oxides in the exhaust stream and thus, in some implementations, may require no aftertreatment system to remove them from the exhaust stream.

It is a challenge to reduce unburned hydrocarbon emissions for gaseous fuelled engines, especially at low engine load conditions, to meet demanding emission regulation targets. A method for reducing unburned hydrocarbon emissions in a lean-burn internal combustion engine that is fuelled with a gaseous fuel comprises adjusting the timing for closing of an intake valve as a function of engine operating conditions by one of advancing timing for closing of the intake valve and closing the intake valve earlier during an intake stroke; and retarding timing for closing of the intake valve and closing the intake valve later during a compression stroke. The volumetric efficiency of the internal combustion engine is reduced and unburned hydrocarbon emissions are maintained below a predetermined level.

A system and method for cylinder deactivation in a multi-cylinder diesel engine comprises pumping air in to an intake manifold of the diesel engine using a turbocharger. Air is pumped in to the intake manifold using an intake air assisting device. And, fuel injection is selectively deactivated to at least one of the cylinders in the diesel engine. An intake valve and an exhaust valve is selectively deactivated for the at least one of the cylinders of the diesel engine.

A multiple variable valve lift apparatus disposed at an intake part and an exhaust part of an engine includes: a moving cam rotating together with a camshaft, being movably disposed in an axial direction of the camshaft, and forming a plurality of cams for realizing valve lift to be different from each other and a cam guide protrusion; an operating unit selectively guiding the cam guide protrusion so as to move the moving cam in an axial direction of the camshaft; a controller controlling an operation of the operating unit; and a valve opening/closing unit opened/closed by contacting any one among the plurality of cams.

A control apparatus for an internal combustion engine includes an electronic control unit that is configured to perform an operation of making a lift amount of a specific valve corresponding to one of either intake ports or exhaust ports for a specific cylinder in which an amount of condensate water produced in the port or flowing into the port is larger than in the other cylinders when the engine is stopped, in a case where production of condensate water in the ports or inflow of condensate water into the ports is predicted.

Methods and systems are provided for compression heating of air. In one example, a method may include, during an engine start and prior to a first combustion event, deactivating cylinder exhaust valves while spinning the engine electrically and unfueled until a threshold intake air temperature is reached, and alternately activating and deactivating the exhaust valves of one or more cylinders to maintain the intake air temperature above the threshold temperature after the first combustion event. In this way, a temperature of an air charge may be increased, resulting in increased fuel economy and decreased vehicle emissions.

A method for controlling intake and exhaust valves of an engine includes: controlling, by an intake continuous variable valve timing (CVVT) device, opening and closing timings of the intake valve; controlling, by an exhaust CVVT device, opening and closing timing of the exhaust valve; determining, by a controller, first to fifth control regions based on engine load and speeds, and a target opening duration of the intake valve and target opening or target closing timings of the intake valve; modifying, by an intake continuous variable valve duration (CVVD) device, current opening and closing timings of the intake valve based on the target opening duration; and advancing or retarding, by the intake CVVD device, the current opening timing of the intake valve while simultaneously retarding or advancing the current closing timing of the intake valve by a predetermined value based on the target opening duration of the intake valve.

Systems and methods for determining operation of a cylinder deactivating/reactivating device are disclosed. In one example, a warm engine is rotated without being supplied fuel to determine the presence or absence of valve actuator degradation. Degraded valve actuators may be determined when there is a lack of a temperature rise in the engine exhaust system.

A method for controlling intake and exhaust valves of an engine includes: Controlling opening and closing timings of the intake and exhaust valves by an intake continuous variable valve timing (CVVT) device and an exhaust CVVT devices; determining, by a controller, target intake and exhaust opening durations of the intake and exhaust valves, and target opening and closing timings of the valves based on an engine load and an engine speed; modifying current intake and exhaust opening durations based on the target opening durations via an intake continuous variable valve duration (CVVD) device and an exhaust CVVD device; adjusting opening or closing timings of the valves to the target opening or closing timings of the valves while maintaining the modified opening durations of the valves.

An exhaust gas control apparatus includes a first catalyst, a filter, and an electronic control unit. The electronic control unit is configured to alternately execute lean control and rich control multiple times. The lean control is control for, over a period longer than a period from when a target air-fuel ratio is set to a predetermined lean air-fuel ratio until an air-fuel ratio of exhaust gas flowing out from the first catalyst becomes greater than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined lean air-fuel ratio. The rich control is control for, over a period longer than a period from when the target air-fuel ratio is set to a predetermined rich air-fuel ratio until the air-fuel ratio of exhaust gas flowing out from the first catalyst becomes smaller than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined rich air-fuel ratio.