The subject matter of this specification can be embodied in, among other things, a gas mixer that includes a convergent-divergent nozzle comprising a convergent portion and a divergent portion and defining a first gas flow path, an air housing comprising an air inlet configured to supply air to the first gas flow path upstream of the convergent-divergent nozzle, a gas housing defining a second gas flow path and including a first gas inlet configured to receive a secondary gas and allow the secondary gas into a second gas flow path, and a gas nozzle positioned parallel to and centrally within the first gas flow path in a convergent portion of the convergent-divergent nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the divergent portion.

The invention reduces exhaust emission by quickly supplying CO2 into a cylinder, and restraining a delay in EGR, when an EGR request occurs. An engine 10 includes an upstream EGR passage 34, a middle EGR passage 36, a downstream EGR passage 38, a bypass passage 40, an EGR valve 42, a changeover valve 44, an EGR cooler 46, a CO2 adsorbent 48. When an EGR request does not occur, the ECU 70 keeps a temperature of the CO2 adsorbent 48 in a release temperature region by the heater 50, and opens the EGR valve 42 by a valve opening set time period t so that a gas in the middle EGR passage 36 is replaced with CO2 released from the CO2 adsorbent. When an EGR request occurs, CO2 accumulated in the middle EGR passage 36 can be quickly supplied into a cylinder, without releasing CO2 from the CO2 adsorbent 48.

This disclosure is intended to suppress a noble metal supported by a three-way catalyst from being deteriorated by oxidation with the execution of fuel cut processing in a suitable manner. A control apparatus for a naturally aspirated gasoline engine is provided with a three-way catalyst, a first throttle valve, a second throttle valve arranged in the intake passage at the downstream side of the first throttle valve, an EGR valve, and a controller. When the controller carries out fuel cut processing and the temperature of the three-way catalyst is equal to or higher than a predetermined temperature, the controller introduces the EGR gas into a cylinder of the gasoline engine as intake air by fully closing the first throttle valve and by opening the EGR valve, and further controls an amount of the EGR gas by adjusting the degree of opening of the second throttle valve.

This disclosure is intended to suppress a noble metal supported by a three-way catalyst from being deteriorated by oxidation with the execution of fuel cut processing in a suitable manner. A control apparatus for a naturally aspirated gasoline engine is provided with a three-way catalyst, a first throttle valve, a second throttle valve arranged in the intake passage at the downstream side of the first throttle valve, an EGR valve, and a controller. When the controller carries out fuel cut processing and the temperature of the three-way catalyst is equal to or higher than a predetermined temperature, the controller introduces the EGR gas into a cylinder of the gasoline engine as intake air by fully closing the first throttle valve and by opening the EGR valve, and further controls an amount of the EGR gas by adjusting the degree of opening of the second throttle valve.

Methods and systems are provided for an engine including a humidity sensor. Degradation of the humidity sensor may be determined based on a change in intake air relative humidity as compared to a change in intake air temperature or pressure, under selected conditions. An amount of exhaust gas recirculated to an engine intake is adjusted differently based on whether the humidity sensor is degraded or functional.

Methods and systems are provided for an engine including a humidity sensor. Degradation of the humidity sensor may be determined based on a change in intake air relative humidity as compared to a change in intake air temperature or pressure, under selected conditions. An amount of exhaust gas recirculated to an engine intake is adjusted differently based on whether the humidity sensor is degraded or functional.

Embodiments for inducing swirl upstream of a compressor are provided. In one example, a method includes during a first condition, flowing exhaust gas from downstream of a turbine to upstream of a compressor via a tangential flow duct of an exhaust gas recirculation (EGR) injector circumferentially surrounding an intake passage upstream of the compressor, and during a second condition, flowing exhaust gas from downstream of the turbine to upstream of the compressor via a radial flow duct of the EGR injector.

Embodiments for inducing swirl upstream of a compressor are provided. In one example, a method includes during a first condition, flowing exhaust gas from downstream of a turbine to upstream of a compressor via a tangential flow duct of an exhaust gas recirculation (EGR) injector circumferentially surrounding an intake passage upstream of the compressor, and during a second condition, flowing exhaust gas from downstream of the turbine to upstream of the compressor via a radial flow duct of the EGR injector.

An exhaust gas recirculation system for an engine includes a conduit, and a mixer. The conduit is configured to direct to direct exhaust gas away from an exhaust manifold. The mixer is configured to direct exhaust gas from the conduit, into an engine air intake system. The mixer is arranged with an exhaust gas mixing volute chamber having a plurality of mixing vanes configured to direct the exhaust gas into a central intake airflow upstream of an intake manifold.

An exhaust gas recirculation system for an engine includes a conduit, and a mixer. The conduit is configured to direct to direct exhaust gas away from an exhaust manifold. The mixer is configured to direct exhaust gas from the conduit, into an engine air intake system. The mixer is arranged with an exhaust gas mixing volute chamber having a plurality of mixing vanes configured to direct the exhaust gas into a central intake airflow upstream of an intake manifold.