Start-up method for heating a selective catalytic reduction (SCR) module in a hybrid propulsion system of a vehicle, comprising an electric motor operatively connected to an internal combustion engine producing exhaust gas, both electric motor and internal combustion engine being operable to power said vehicle, and said internal combustion engine being in fluid communication with an exhaust aftertreatment system having an exhaust passage and comprising the SCR module, said SCR module being disposed in said exhaust passage downstream of said engine and said electric motor, the method comprising the steps of: operating the engine in a start-up mode with a torque restriction on the engine, allowing the SCR module to convert NOx emission; supplying a surplus amount of a reducing agent to the exhaust gas at a position between the engine and the SCR module, the surplus amount of the reducing agent being larger than a required amount of reducing agent for converting NOx emission from the engine; heating said SCR module to a working temperature; and terminating the start-up mode, thereby terminating the torque restriction on the engine and the supply of the surplus amount of the reducing agent.

Start-up method for heating a selective catalytic reduction (SCR) module in a hybrid propulsion system of a vehicle, comprising an electric motor operatively connected to an internal combustion engine producing exhaust gas, both electric motor and internal combustion engine being operable to power said vehicle, and said internal combustion engine being in fluid communication with an exhaust aftertreatment system having an exhaust passage and comprising the SCR module, said SCR module being disposed in said exhaust passage downstream of said engine and said electric motor, the method comprising the steps of: operating the engine in a start-up mode with a torque restriction on the engine, allowing the SCR module to convert NOx emission; supplying a surplus amount of a reducing agent to the exhaust gas at a position between the engine and the SCR module, the surplus amount of the reducing agent being larger than a required amount of reducing agent for converting NOx emission from the engine; heating said SCR module to a working temperature; and terminating the start-up mode, thereby terminating the torque restriction on the engine and the supply of the surplus amount of the reducing agent.

An EGR control apparatus for the engine includes an ECU. The ECU calculates a LP-side correction coefficient Kcor_LP and a HP-side correction coefficient Kcor_HP such that they include a LP-side FB correction value Dfb_LP and a HP-side FB correction value Dfb_HP that are calculated using equations (9) and (17) such that an absolute value of an EGR amount error E_egr is reduced, and a LP-side learned value CorMAP_LP/HP-side learned value CorMAP_HP learned when a LP ratio R_LP=1/R_LP=0 holds, calculates a target LP opening _LP_dmd and a target HP opening _HP_dmd using the LP-side correction coefficient Kcor_LP and the HP-side correction coefficient Kcor_HP, and controls a LP opening _LP and a HP opening _HP such that they become equal to the target LP opening _LP_dmd and the target HP opening _HP_dmd.

Substances in external EGR gas are smoothly guided to a combustion chamber. An intake passage includes: a main intake passage including intake ports and communicating with a combustion chamber and having a supercharger interposed in the main intake passage; and a bypass passage branching off from the main intake passage upstream of the supercharger, and connected downstream of the supercharger; a flow rage adjustment valve changing a cross-sectional flow area of the bypass passage. The bypass passage is provided above the main intake passage, and includes an upper passage to which an EGR passage is connected.

Methods and systems are provided for adjusting amount of directly injected fuel scavenged via a second exhaust manifold of a split exhaust engine system. In one example, a method may include adjusting a start of injection of a fuel direct injection into an engine cylinder, the cylinder including a first exhaust valve coupled to a first exhaust manifold and a second exhaust valve coupled to a second exhaust manifold, the second exhaust manifold coupled to an intake of the engine, based on a closing timing of the second exhaust valve and dependent on an operating condition, and adjusting a position of a bypass valve of the second exhaust manifold based on the adjusted start of injection. In this way, the amount of scavenged fuel may be increased or decreased based on the operating condition.

Methods and systems are provided for adjusting amount of directly injected fuel scavenged via a second exhaust manifold of a split exhaust engine system. In one example, a method may include adjusting a start of injection of a fuel direct injection into an engine cylinder, the cylinder including a first exhaust valve coupled to a first exhaust manifold and a second exhaust valve coupled to a second exhaust manifold, the second exhaust manifold coupled to an intake of the engine, based on a closing timing of the second exhaust valve and dependent on an operating condition, and adjusting a position of a bypass valve of the second exhaust manifold based on the adjusted start of injection. In this way, the amount of scavenged fuel may be increased or decreased based on the operating condition.

Various embodiments include a method of operating a diesel engine having an exhaust tract and an SCR-combined diesel particulate filter in the exhaust tract, wherein an aqueous urea solution is introduced into the exhaust tract, and an exhaust gas recirculation apparatus having an exhaust gas recirculation conduit branching off downstream of the SCR-combined diesel particulate filter for performing a low-pressure exhaust gas recirculation comprising: measuring an NH.sub.3 concentration in exhaust gas downstream of the SCR-combined diesel particulate filter; and upon exceeding a threshold value of the measured NH.sub.3 concentration, reducing the low-pressure exhaust gas recirculation rate based at least in part on the measured NH.sub.3 concentration.

A convergent nozzle is in a mixer housing and in a flow path from an air inlet of the mixer to an outlet of the mixer. A convergent-divergent nozzle is in the mixer housing and includes an air-exhaust gas inlet in fluid communication to receive fluid flow from the convergent nozzle and from the interior of the exhaust gas housing. A first nozzle module is configured to be received in the mixer housing and, when received in the mixer housing, define at least a portion of the convergent nozzle or the convergent-divergent nozzle. A second nozzle module is configured to be received in the mixer housing separate from the first nozzle module. The second nozzle module, when received in the mixer housing, is configured to define at least a portion of the convergent or the convergent-divergent nozzle. The second nozzle module has a different flow characteristic than the first nozzle module.

An internal-combustion engine includes: a supercharger; an EGR passage connecting between an exhaust passage and an intake passage downstream of the supercharger; a control device controlling EGR; and an intake pressure sensor that detects a supercharge pressure being a gas pressure in the intake passage downstream of the supercharger. A comparison-target pressure is a higher one of a target supercharge pressure and an actual supercharge pressure detected by the intake pressure sensor. The control device compares the comparison-target pressure with an exhaust gas pressure in the exhaust passage. When the comparison-target pressure is higher than the exhaust gas pressure, the EGR is prohibited and an EGR valve is fully closed. When the comparison-target pressure is lower than the exhaust gas pressure, the EGR is permitted.

An internal-combustion engine includes: a supercharger; an EGR passage connecting between an exhaust passage and an intake passage downstream of the supercharger; a control device controlling EGR; and an intake pressure sensor that detects a supercharge pressure being a gas pressure in the intake passage downstream of the supercharger. A comparison-target pressure is a higher one of a target supercharge pressure and an actual supercharge pressure detected by the intake pressure sensor. The control device compares the comparison-target pressure with an exhaust gas pressure in the exhaust passage. When the comparison-target pressure is higher than the exhaust gas pressure, the EGR is prohibited and an EGR valve is fully closed. When the comparison-target pressure is lower than the exhaust gas pressure, the EGR is permitted.