An internal combustion engine has an exhaust gas recirculation system for recirculating exhaust gases from the internal combustion engine into an intake region of the internal combustion engine. The exhaust gas recirculation system includes the following components: at least one exhaust gas cooler through which a first flow path for recirculating exhaust gas extends, having at least one first cooling stage and at least one additional cooling stage, at least one flap arrangement by which the at least one additional cooling stage can be connected, a bypass line through which a second flow path for recirculating exhaust gas extends and by which the exhaust gas cooler can be bypassed during the recirculation of exhaust gas, and an EGR valve having at least three possible positions.

An internal combustion engine has an exhaust gas recirculation system for recirculating exhaust gases from the internal combustion engine into an intake region of the internal combustion engine. The exhaust gas recirculation system includes the following components: at least one exhaust gas cooler through which a first flow path for recirculating exhaust gas extends, having at least one first cooling stage and at least one additional cooling stage, at least one flap arrangement by which the at least one additional cooling stage can be connected, a bypass line through which a second flow path for recirculating exhaust gas extends and by which the exhaust gas cooler can be bypassed during the recirculation of exhaust gas, and an EGR valve having at least three possible positions.

A system includes an internal combustion engine having a number of cylinders, with at least one of the cylinders plumbed to have a complete recycle of the exhaust gases from the cylinder. The system further includes the completely recycled cylinder having an EGR stroke cycle, and the non-recycled cylinders of the engine having an exhaust stroke cycle. The system includes the EGR stroke cycle being distinct from the exhaust stroke cycle. An amount and composition of the exhaust gases from the recycled cylinder are distinct from the amount and composition of the exhaust gases from the non-recycled cylinders, at least at certain operating conditions of the engine.

An exhaust emission control system of an engine is provided, which includes a NO.sub.x catalyst disposed in an exhaust passage for storing NO.sub.x within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NO.sub.x when the air-fuel ratio is approximately stoichiometric or rich. A processor executes a NO.sub.x reduction controlling module for performing a NO.sub.x reduction control in which a fuel injector performs a post injection to control the air-fuel ratio to a target ratio, and an EGR controlling module for controlling an EGR valve to recirculate EGR gas. In the NO.sub.x reduction control, the EGR controlling module controls an opening of the EGR valve to a target opening smaller than when the NO.sub.x reduction control is not performed. The NO.sub.x reduction controlling module starts the control after the EGR valve opening is controlled to the target opening.

An exhaust emission control system of an engine is provided, which includes a NO.sub.x catalyst disposed in an exhaust passage for storing NO.sub.x within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NO.sub.x when the air-fuel ratio is approximately stoichiometric or rich. A processor executes a NO.sub.x reduction controlling module for performing a NO.sub.x reduction control in which a fuel injector performs a post injection to control the air-fuel ratio to a target ratio, and an EGR controlling module for controlling an EGR valve to recirculate EGR gas. In the NO.sub.x reduction control, the EGR controlling module controls an opening of the EGR valve to a target opening smaller than when the NO.sub.x reduction control is not performed. The NO.sub.x reduction controlling module starts the control after the EGR valve opening is controlled to the target opening.

Systems, apparatus and methods include control techniques for controlling operation of pre-mixed internal combustion engines in response to a load shedding event. The control techniques determine, in response to the load shedding event, a number of cycles in which to skip combustion of the fuel in the at least one cylinder based on an air-fuel ratio limit in the exhaust flow, prevent combustion of the fuel in the at least one cylinder during the number of skipped cycles, and combust the fuel in the at least one cylinder each time the number of skipped cycles are complete.

An internal combustion engine in which a fuel reforming operation in a fuel reformation cylinder (2) is not executed and a warming operation for raising the temperature of the fuel reformation cylinder (2) is executed, when a gas temperature of a fuel reformation chamber (23) at a time point when a piston (22) in the fuel reformation cylinder (2) reaches a compression top dead point is estimated to fall short of a reforming operation allowable lower limit gas temperature. For example, EGR gas is introduced to the fuel reformation chamber (23) without cooling the EGR gas. Further, during a predetermined period from the expansion stroke to an exhaust stroke of an output cylinder (3), exhaust gas warming fuel is supplied to a combustion chamber (33). Further, the fuel is combusted in the fuel reformation chamber (23).

A heat exchanger disposed in an exhaust heat recovery device exchanges heat between exhaust and cooling fluid. An inner shell of the heat exchanger externally surrounds an exhaust pipe and forms a heat exchange space between the inner shell and the exhaust pipe to accommodate arranged plates. An outer shell of the heat exchanger includes an EGR opening that leads the exhaust to an inlet system of an internal combustion engine. The outer shell forms an external space leading to the EGR opening between the outer shell and the inner shell. The inner shell includes at least one aperture area that communicates the heat exchange space with the external space.

A multi-cylinder engine includes an engine body having first and second cylinder groups, first and second exhaust passage groups each having a plurality of independent exhaust passage parts and a collective exhaust passage part, and an exhaust gas recirculation (EGR) passage. In a plan view in cylinder axis directions, the passage groups are disposed adjacent to each other, and, in the first exhaust passage group, a first independent exhaust part of the plurality of independent exhaust passage parts is connected to the EGR passage and a second independent exhaust passage part is connected to the collective exhaust passage part so as to be directed to a connection of the first independent exhaust passage part to the collective exhaust passage part, and in the second exhaust passage group, an opening of the collective exhaust passage part is offset toward the first exhaust passage group in a lineup direction.

A multi-cylinder engine includes an engine body having first and second cylinder groups, first and second exhaust passage groups each having a plurality of independent exhaust passage parts and a collective exhaust passage part, and an exhaust gas recirculation (EGR) passage. In a plan view in cylinder axis directions, the passage groups are disposed adjacent to each other, and, in the first exhaust passage group, a first independent exhaust part of the plurality of independent exhaust passage parts is connected to the EGR passage and a second independent exhaust passage part is connected to the collective exhaust passage part so as to be directed to a connection of the first independent exhaust passage part to the collective exhaust passage part, and in the second exhaust passage group, an opening of the collective exhaust passage part is offset toward the first exhaust passage group in a lineup direction.