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.

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.

An internal combustion engine includes combustion chambers, each having a controllable intake valve opening and closing an intake port, a controllable exhaust valve opening and closing an exhaust port, a piston displaceable back and forth in the combustion chamber between a top dead center and a bottom dead center, and a fuel injector. The engine further including an intake manifold connected to the intake port of each combustion chamber. The engine can be operated in a low load mode, wherein each combustion chamber is driven in four-stroke operation including a 720 crank angle degrees cycle, and opens the intake port during the exhaust stroke, the intake port starting to open in 610-690 CAD, closing the exhaust port during the exhaust stroke, becoming fully closed in 630-710 CAD, forcing exhaust gas into the intake manifold by the piston, and mixing fuel and exhaust gas in the intake manifold.

An internal combustion engine includes combustion chambers, each having a controllable intake valve opening and closing an intake port, a controllable exhaust valve opening and closing an exhaust port, a piston displaceable back and forth in the combustion chamber between a top dead center and a bottom dead center, and a fuel injector. The engine further including an intake manifold connected to the intake port of each combustion chamber. The engine can be operated in a low load mode, wherein each combustion chamber is driven in four-stroke operation including a 720 crank angle degrees cycle, and opens the intake port during the exhaust stroke, the intake port starting to open in 610-690 CAD, closing the exhaust port during the exhaust stroke, becoming fully closed in 630-710 CAD, forcing exhaust gas into the intake manifold by the piston, and mixing fuel and exhaust gas in the intake manifold.

A control device is provided for an engine in which premixed compression ignition combustion is carried out. The device includes an air amount adjusting mechanism, a variable valve mechanism, an exhaust choke valve, a water temperature sensor, and a processor. The processor controls the variable valve mechanism so that a valve overlap period of a given amount or more is formed in a low-load range where the engine load is low, and controls an injector, the air amount adjusting mechanism, and the exhaust choke valve so that A/F lean mixture gas is formed inside a combustion chamber, and premixed compression ignition combustion of the mixture gas is carried out. During the operation in the low-load range, the combustion controlling module makes an opening of the exhaust choke valve when a temperature parameter is low, smaller than that when the temperature parameter is high.

An exhaust gas recirculation (EGR) system for an internal combustion (IC) engine. The EGR system has a first cooler configured to cool exhaust from an exhaust system of the IC and to drain exhaust liquid formed by the cooling. The EGR system has a mixture chamber configured to mix exhaust cooled by the first cooler with intake air to form an exhaust-air mixture. The EGR system has a second cooler configured to cool the exhaust-air mixture. The EGR system has a heat exchange system for circulating and cooling coolant fluid used by the first and second coolers, and includes a split valve configured to divide coolant fluid flow between the first and second coolers. The EGR system has an engine control module configured to adjust the split valve based on comparing a temperature of the exhaust-air mixture to a determined dewpoint temperature of the exhaust-air mixture.

An exhaust gas recirculation (EGR) system for an internal combustion (IC) engine. The EGR system has a first cooler configured to cool exhaust from an exhaust system of the IC and to drain exhaust liquid formed by the cooling. The EGR system has a mixture chamber configured to mix exhaust cooled by the first cooler with intake air to form an exhaust-air mixture. The EGR system has a second cooler configured to cool the exhaust-air mixture. The EGR system has a heat exchange system for circulating and cooling coolant fluid used by the first and second coolers, and includes a split valve configured to divide coolant fluid flow between the first and second coolers. The EGR system has an engine control module configured to adjust the split valve based on comparing a temperature of the exhaust-air mixture to a determined dewpoint temperature of the exhaust-air mixture.

An object of the present invention is to predict change of a combustion limit due to cycle variation of temperature and an EGR ratio and perform correction every cycle to decrease an amount of combustion consumption. Therefore, in an internal combustion engine control device that controls an internal combustion engine including a cylinder and an exhaust pipe, the internal combustion engine control device includes a control unit configured to perform EGR control of controlling an exhaust gas in the exhaust pipe to return to an inner cylinder of the cylinder, obtain temperature of the gas in the internal cylinder and an EGR ratio in a state where both an intake valve and an exhaust valve are closed in an combustion cycle, and correct a combustion parameter in a same combustion cycle as the combustion cycle on the basis of the obtained gas temperature and the obtained EGR ratio.

An object of the present invention is to predict change of a combustion limit due to cycle variation of temperature and an EGR ratio and perform correction every cycle to decrease an amount of combustion consumption. Therefore, in an internal combustion engine control device that controls an internal combustion engine including a cylinder and an exhaust pipe, the internal combustion engine control device includes a control unit configured to perform EGR control of controlling an exhaust gas in the exhaust pipe to return to an inner cylinder of the cylinder, obtain temperature of the gas in the internal cylinder and an EGR ratio in a state where both an intake valve and an exhaust valve are closed in an combustion cycle, and correct a combustion parameter in a same combustion cycle as the combustion cycle on the basis of the obtained gas temperature and the obtained EGR ratio.

A compression ignition gasoline engine includes a fuel injection valve for injecting fuel containing gasoline as a main component into a cylinder; an EGR device operative to perform high-temperature EGR of introducing burnt gas generated in the cylinder into the cylinder at a high temperature; and a combustion control unit for controlling the fuel injection valve and the EGR device in such a way that HCCI combustion in which fuel injected from the fuel injection valve self-ignites within the cylinder occurs. The combustion control unit controls the EGR device, in at least a partial load operating range in which HCCI combustion is performed, in such a way that the EGR rate increases, as compared with a low load condition, in a high load condition in which G/F being a ratio between a total amount of gas and a fuel amount within the cylinder decreases.