Methods and systems are provided for improving catalyst temperature control while reducing oxygen saturation. Secondary air is injected at a location downstream of the catalyst during selected conditions. A mixing valve position is coordinated with the air injection to improve local turbulence and thereby enhance air and fuel mixing in the exhaust passage, in at least one example.

Methods and systems are provided for an exhaust aftertreatment system. In one example, a system comprises an air injector positioned to inject air between a first catalyst and a second catalyst in response to an oxygen concentration of an exhaust gas falling below a threshold concentration while exhaust gas temperatures are less than a threshold temperature.

In one aspect, an aspiration system for a work vehicle includes an exhaust tube extending along a flow direction from an upstream end to a downstream end. The exhaust tube defines an exhaust passage extending from the upstream end of the exhaust tube to the downstream end of the exhaust tube. The exhaust tube includes a venturi portion. The aspiration system also includes an aspiration tube in flow communication with the venturi portion and configured to receive an aspirated airflow. The system further includes a flow adjustment mechanism provided in operative association with venturi portion such that the flow adjustment mechanism is configured to adjust a cross-sectional flow area of the venturi portion of the exhaust tube.

Methods and systems are provided for heating an exhaust particulate filter (PF) to enable filter generation. In one example, a method may include adjusting engine air fuel ratio and injecting secondary air flow upstream of the PF to increase PF temperature. The level of engine air fuel ratio adjustment and the amount of secondary air injection upstream of the PF may be adjusted to account for enrichment induced cooling at a three-way catalyst (TWC) positioned upstream of the PF.

A method for operating a petrol engine, in which air is introduced into an exhaust tract through which exhaust gas from the petrol engine can flow, bypassing the petrol engine, includes introducing the air into the exhaust tract at a point arranged downstream of a first three-way catalytic converter arranged in the exhaust tract and upstream of a second three-way catalytic converter arranged in the exhaust tract downstream of the first three-way catalytic converter, while the petrol engine is operated with a sub-stoichiometric combustion air ratio, where a desulphurization of the second three-way catalytic converter is effected.

Methods and systems are provided for expediting emission control device heating. In one example, a method may include flowing air from an intake of an engine to one or more emission control devices via an air injection system while operating a turbocharger via an electric motor to maintain a desired airflow to the engine in response to an emission control device heating condition. In this way, fresh air is provided to the one or more emission control devices without degrading engine performance or increasing engine speed.

The present application provides a reductant dosing system for an SCR catalyst comprising an injector, a storage tank and a reductant pump arranged in a first fluid line between the storage tank and the injector for pumping reductant from the storage tank to the injector. The reductant dosing system comprises pressurizing means for pressurizing the storage tank.

An exhaust aftertreatment system includes a first catalytic converter, an oxidation catalyst including a storage catalyst, an air injector, and a cooling unit. The exhaust aftertreatment system is fluidly coupled to an output of a spark-ignited internal combustion engine that operates in the rich regime during acceleration and the lean regime during deceleration. In one aspect, the storage catalyst stores ammonia produced while the engine operates in the rich regime. The stored ammonia reacts with nitrogen oxide compounds produced when the engine operates in the lean regime. In another aspect, the nitrogen oxide compounds react with ammonia produced while the engine operates in the rich regime.

Methods and systems are provided for expediting emission control device heating. In one example, a method may include flowing air from an intake of an engine to one or more emission control devices via an air injection system while operating a turbocharger via an electric motor to maintain a desired airflow to the engine in response to an emission control device heating condition. In this way, fresh air is provided to the one or more emission control devices without degrading engine performance or increasing engine speed.

An injection controller that is applied to an exhaust purification system including an injector that is located in an exhaust passage of an internal combustion engine and injects to supply a reducing agent in a liquid state to a NOx purification catalyst purifying NOx in an exhaust gas, and a pump that pressurizes and pumps the reducing agent to the injector through a reducing-agent passage. The injection controller includes an acquisition unit configured to acquire a variation quantity of a rotational speed of the pump caused in response to an injection of the injector or a correlation value that is a value correlative to the variation quantity, as a rotational variation parameter, and a determination unit configured to determine whether an air mixing exists in the reducing-agent passage based on the rotational variation parameter.