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).

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).

An engine, an intake passage to introduce intake air to the engine, an exhaust passage to discharge exhaust air from the engine, and a high-temperature duct connected to the intake passage to introduce high-temperature air around the exhaust passage into the engine are provided in an engine compartment. The intake passage includes an intake-air inlet port to introduce outside air as low-temperature air. A passage switching valve provided between the intake passage and the high-temperature duct switches passages of the high-temperature air from the high-temperature duct and the low-temperature air from the intake air inlet port so as to selectively flow the air downstream of the intake passage. A valve control unit controls switching according to the temperature inside the compartment.

An engine system includes an internal combustion engine having an intake duct and an exhaust duct; a flow control module fluidly coupled to the intake duct; a compressor in fluid communication with the intake duct via the flow control module; a heat exchanger having an exhaust flow path in fluid communication with the exhaust duct, and having an oxidizer flow path, an outlet of the compressor being in selective fluid communication with the intake duct via the flow control module and the oxidizer flow path of the heat exchanger; a first temperature sensor in fluid communication with the intake duct; and a controller operatively coupled to the flow control module and the first temperature sensor, the controller being configured to actuate the flow control module between a first configuration and a second configuration based at least in part on a signal from the first temperature sensor.

An engine system includes an internal combustion engine having an intake duct and an exhaust duct; a flow control module fluidly coupled to the intake duct; a compressor in fluid communication with the intake duct via the flow control module; a heat exchanger having an exhaust flow path in fluid communication with the exhaust duct, and having an oxidizer flow path, an outlet of the compressor being in selective fluid communication with the intake duct via the flow control module and the oxidizer flow path of the heat exchanger; a first temperature sensor in fluid communication with the intake duct; and a controller operatively coupled to the flow control module and the first temperature sensor, the controller being configured to actuate the flow control module between a first configuration and a second configuration based at least in part on a signal from the first temperature sensor.

A method and internal combustion engine system are provided for keeping an exhaust gas aftertreatment system within its working temperature range during an idle or motoring engine operation mode of an internal combustion engine. The method includes sensing the temperature of the gas at the gas intake side of the internal combustion engine and/or of the exhaust gas; determining whether or not the sensed temperature value is in a predetermined temperature interval or below a predetermined temperature threshold; determining whether the internal combustion engine is in idle or motoring engine operation mode; in case the internal combustion engine is determined to be in an idle or motoring engine operation mode, controlling the temperature of the gas at the gas intake side of the internal combustion engine to be within the predetermined temperature range or below the predetermined temperature threshold by recirculating exhaust gas through a connecting duct by controlling at least one valve.