Systems and methods of engine exhaust air injection before and after catalytic converters

A method comprising:

• operating an engine system including an engine configured to consume fuel and air so as to generate an exhaust gas stream;
• channeling the exhaust gas stream from the engine to a tailpipe via an exhaust system;
• arranging a catalytic converter in the exhaust system;
• arranging a first air injector in the exhaust system at a position upstream from the catalytic converter, the first air injector configured to selectively inject air into the exhaust system upstream from the catalytic converter;
• arranging a second air injector in the exhaust system at a position downstream from the catalytic converter, the second air injector configured to selectively inject air into the exhaust system downstream from the catalytic converter;
• and
• executing an air injection control via a controller operatively connected to the first air injector and the second air injector, the air injection control comprising:
• injecting air only via the first air injector when a temperature of the exhaust gas stream upstream from the catalytic converter is below a first threshold temperature;
• injecting air only via the second air injector when the temperature of the exhaust gas stream upstream from the catalytic converter is above a second threshold temperature that is different than the first threshold temperature;
• and
• injecting air via the first air injector and the second air injector when the temperature of the exhaust gas stream upstream from the catalytic converter is between the first threshold temperature and the second threshold temperature.

An engine system comprising:

• an engine configured to consume fuel and air so as to generate an exhaust gas stream;
• an exhaust system configured to channel the exhaust gas stream from the engine to a tailpipe;
• a catalytic converter disposed in the exhaust system;
• a first air injector disposed in the exhaust system upstream from the catalytic converter, the first air injector configured to inject air into the exhaust system upstream from the catalytic converter;
• a second air injector disposed in the exhaust system downstream from the catalytic converter, the second air injector configured to inject air into the exhaust system downstream from the catalytic converter;
• a first exhaust gas temperature sensor disposed in the exhaust gas stream upstream from the catalytic converter, the first exhaust gas temperature sensor configured to detect a first exhaust gas temperature;
• a second exhaust gas temperature sensor disposed in the exhaust gas stream downstream from the catalytic converter, the second exhaust gas temperature sensor configured to detect a second exhaust gas temperature;
• and
• a controller operatively connected to the first and second air injectors and the first and second exhaust gas temperature sensors, the controller configured to execute an air injection control configured to:
• inject air only via the first air injector when the detected first exhaust gas temperature is below a first threshold temperature,
• inject air only via the second air injector when the detected first exhaust gas temperature is above a second threshold temperature that is different than the first threshold temperature, and
• inject air via the first and second air injectors simultaneously when the detected second exhaust gas temperature is at a maximum temperature limit of the catalytic converter.