US Patent 9574524 Method and internal combustion engine system for keeping an exhaust gas aftertreatment system within its working temperature range

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.