Abstract: A method of controlling engine internal exhaust gas recirculation may include estimating a flow restriction through a diesel particulate filter in an exhaust system of an engine assembly and adjusting a backpressure control valve in the exhaust system downstream of the diesel particulate filter based on the flow restriction. A controlled amount of internal exhaust gas recirculation may be provided to the engine assembly based on adjusting the backpressure control valve.

Abstract: An engine assembly includes a camshaft having an exhaust cam lobe defining an exhaust lift region and an exhaust base circle region and an EGR cam lobe defining an EGR lift region and an EGR base circle region. The EGR lift region is rotationally offset from the exhaust lift region and the EGR base circle region is rotationally aligned with the exhaust lift region. An exhaust valve lift mechanism is engaged with an exhaust valve, the exhaust cam lobe and the EGR cam lobe and is operable in first and second modes. The exhaust valve remains closed when the EGR lift region engages the exhaust valve lift mechanism during the second mode and the exhaust valve is opened when the EGR lift region engages the exhaust valve lift mechanism during the first mode to provide exhaust gas flow into the combustion chamber during an intake stroke of the combustion chamber.

Abstract: A method for controlling re-circulation of exhaust gas (EGR) in an internal combustion engine includes receiving a signal indicative of an engine operating temperature and comparing the engine operating temperature to a first predetermined IEGR threshold. When the engine operating temperature is less than the first predetermined internal EGR threshold, a first internal EGR mode is activated, whereby engine emissions may be reduced or combustion stability may be enhanced. When the engine operating temperature is greater than the first predetermined internal EGR threshold, the first internal EGR mode is deactivated, and a second internal EGR mode is activated, whereby emissions may be reduced as exhaust system heating is accelerated. When the operating temperature is greater than the second temperature threshold, the second internal EGR mode may be deactivated a third mode may be enabled with only external EGR.

Abstract: In an exemplary embodiment, an internal combustion engine includes an oxidation catalyst configured to receive an exhaust gas flow from the internal combustion engine, a urea injector positioned downstream of the oxidation catalyst to inject a urea flow into the exhaust gas flow and a mixer positioned downstream of the urea injector to mix the exhaust gas flow and the urea flow to form a mixed exhaust gas and urea flow. The engine also includes a particulate filter and catalytic reduction assembly positioned downstream of the mixer to receive the mixed exhaust and urea flow from the mixer to form a treated exhaust gas flow and an exhaust gas recirculation system coupled to the particulate filter to receive a portion of the treated exhaust gas flow and recirculate the portion of the exhaust gas flow to be mixed with a fresh air flow for the internal combustion engine.

Abstract: A method for controlling re-circulation of exhaust gas (EGR) in an internal combustion engine includes receiving a signal indicative of an engine operating temperature and comparing the engine operating temperature to a first predetermined IEGR threshold. When the engine operating temperature is less than the first predetermined internal EGR threshold, a first internal EGR mode is activated, whereby engine emissions may be reduced or combustion stability may be enhanced. When the engine operating temperature is greater than the first predetermined internal EGR threshold, the first internal EGR mode is deactivated, and a second internal EGR mode is activated, whereby emissions may be reduced as exhaust system heating is accelerated. When the operating temperature is greater than the second temperature threshold, the second internal EGR mode may be deactivated a third mode may be enabled with only external EGR.

Abstract: A method of controlling engine internal exhaust gas recirculation may include estimating a flow restriction through a diesel particulate filter in an exhaust system of an engine assembly and adjusting a backpressure control valve in the exhaust system downstream of the diesel particulate filter based on the flow restriction. A controlled amount of internal exhaust gas recirculation may be provided to the engine assembly based on adjusting the backpressure control valve.

Abstract: An engine assembly includes a camshaft having an exhaust cam lobe defining an exhaust lift region and an exhaust base circle region and an EGR cam lobe defining an EGR lift region and an EGR base circle region. The EGR lift region is rotationally offset from the exhaust lift region and the EGR base circle region is rotationally aligned with the exhaust lift region. An exhaust valve lift mechanism is engaged with an exhaust valve, the exhaust cam lobe and the EGR cam lobe and is operable in first and second modes. The exhaust valve remains closed when the EGR lift region engages the exhaust valve lift mechanism during the second mode and the exhaust valve is opened when the EGR lift region engages the exhaust valve lift mechanism during the first mode to provide exhaust gas flow into the combustion chamber during an intake stroke of the combustion chamber.

Abstract: An engine assembly may include an engine structure, an exhaust system, an intake system, a valvetrain assembly and an exhaust gas recirculation system. The engine structure may define a combustion chamber and intake and exhaust ports in communication with the combustion chamber. The exhaust system may include an exhaust conduit in communication with exhaust port. The intake system may include a turbocharger in communication with the exhaust conduit and the intake port. The valvetrain assembly may provide internal recirculation of exhaust gas within the combustion chamber. The exhaust gas recirculation system may include an EGR line extending from the exhaust conduit at a location between the turbocharger and an outlet of the exhaust conduit to the intake system and may provide communication between the intake and exhaust systems.

Abstract: In an exemplary embodiment, an internal combustion engine includes an oxidation catalyst configured to receive an exhaust gas flow from the internal combustion engine, a urea injector positioned downstream of the oxidation catalyst to inject a urea flow into the exhaust gas flow and a mixer positioned downstream of the urea injector to mix the exhaust gas flow and the urea flow to form a mixed exhaust gas and urea flow. The engine also includes a particulate filter and catalytic reduction assembly positioned downstream of the mixer to receive the mixed exhaust and urea flow from the mixer to form a treated exhaust gas flow and an exhaust gas recirculation system coupled to the particulate filter to receive a portion of the treated exhaust gas flow and recirculate the portion of the exhaust gas flow to be mixed with a fresh air flow for the internal combustion engine.

Abstract: An engine assembly may include a first exhaust valve lift assembly, a first exhaust valve, and a first camshaft. The first exhaust valve lift assembly may be operable in first and second operating modes. The first exhaust valve may be engaged with the first exhaust valve lift assembly and may be in communication with an engine combustion chamber. The first camshaft may include a first exhaust lobe engaged with the first exhaust valve lift assembly and defining a profile including a first exhaust region and a first exhaust gas recirculation (EGR) region. The first exhaust valve may remain closed when the first EGR region engages the first exhaust valve lift assembly during the first operating mode and may be opened when the first EGR region engages the first exhaust valve lift assembly during the second operating mode to provide exhaust gas flow into the combustion chamber during an intake stroke.