Methods and systems are provided for maintaining a temperature of exhaust gases of an engine within a temperature range at which catalytic conversion is most efficient. In one example, a method for controlling a temperature of exhaust gases entering a Selective Catalytic Reduction (SCR) system for an engine comprises delivering pressurized air into the exhaust gases upstream of the SCR system, the pressurized air cooled by an air cooler; and adjusting a degree of pressurization by adjusting operation of a turbocharger pressurizing the pressurized air. In one embodiment, the air cooler may be a charge air cooler of a primary turbocharger of the engine, which may flow pressurized air both to the engine and to the SCR system. In other embodiments, the air may be pressurized by an air pump or a secondary dilution turbocharger, and cooled by a secondary charge air cooler.

In an internal combustion engine system having an emissions control system including an electrically heated catalyst (E-cat) and an E-compressor (either standalone or part of an E-turbocharger), a method for operating the emissions control system includes predicting that a cold start of the engine is imminent, activating the E-cat and the E-compressor in response to the prediction, and monitoring a characteristic parameter Pe of the E-cat as it changes. The E-compressor speed Nc is regulated to change in proportion to the changing Pe while the E-cat is activated. If no engine start occurs, the E-cat is deactivated, and speed Nc is regulated to track the changing Pe.

An engine assembly and a method of control thereof is provided. The engine assembly comprises: an exhaust gas aftertreatment device having an inlet for receiving exhaust gases leaving an engine; a heater for selectively heating gases at or upstream of the exhaust gas aftertreatment device; an air moving device for driving a flow of gases into the inlet of the exhaust gas aftertreatment device when the engine is in a non-running condition; and a controller configured to, prior to the engine being started: operate the heater to heat gases at or upstream of the inlet; and operate the air moving device to drive a flow of gases into the inlet to thereby heat the exhaust gas treatment device.

Methods and systems are provided for expediting exhaust catalyst light-off prior to an anticipated engine cold-start event. In one example, a method may include, in anticipation of an engine cold-start, preemptively operating an electric booster and routing compressed air to the catalyst to increase a temperature of the exhaust catalyst while maintaining the engine inactive.

In a turbocharged internal combustion engine (ICE) system, a catalytic treatment device receives exhaust gases from the ICE after they have passed through the turbocharger turbine. The system includes a secondary air pump (SAP) for injecting pressurized air into the exhaust gases ahead of the catalytic treatment device. The SAP is a single-stage centrifugal compressor that includes an air recirculation passage for causing a first portion of the air pressurized by the SAP to be continuously recirculated back to the inlet of the SAP, which is effective for heating the air in the volute of the SAP. A second portion of the pressurized air, having thereby been heated, is injected into the exhaust gases proceeding toward the catalytic treatment device.

An exhaust aftertreatment system for an internal combustion engine includes an outer casing defining an exhaust flow path for exhaust gases from the internal combustion engine, a selective catalytic reduction unit provided in the exhaust flow path for reducing nitrogen oxides, a urea dosing device for adding urea to the exhaust flow upstream of the selective catalytic reduction unit, and a rotatable mixer device for mixing the urea with exhaust gases upstream of the selective catalytic reduction unit. The exhaust aftertreatment system further comprises an air inlet valve provided upstream of the mixer device for introducing air into the exhaust flow path, and an electric motor arranged for rotating the mixer device to create a suction of air into the exhaust flow path via the air inlet valve.

An EHC line leakage diagnosis method can operate a heater of an oxygen detector when satisfying one or more conditions of an engine off time, a coolant temperature, and an outside air temperature by a diagnosis controller upon the key-on of the non-operation of an engine, and then, determine the normality or abnormality of a temperature drop using a change in a temperature value of a signal value and the temperature value detected by the oxygen detector after an air pump is driven, and then confirm the leakage of an exhaust line and a line on the rear end portion of an EHC valve of an air line using the number of times of the occurrence of the abnormality of the temperature drop, and can perform the failure diagnosis without generating the exhaust gas by not operating an engine.

A method for checking the operability of a secondary-air system of an internal combustion engine includes measuring a first pressure between a first secondary-air pump and a first master secondary-air valve as well as a second master secondary-air valve, measuring a second pressure between a second secondary-air pump and a first slave secondary-air valve and a second slave secondary-air valve, controlling the first master secondary-air valve and the first slave secondary-air valve together, and controlling the second master secondary-air valve and the second slave secondary-air valve together. A secondary-air system includes a first control and a second control, wherein a first master secondary-air valve and a first slave secondary-air valve are controllable together by the first control and wherein a second master secondary-air valve and a second slave secondary-air valve are controllable together by the second control.

An air supply device for an electrically heated catalyst is proposed. The device includes an electronic supercharger fluidly connected to an intake manifold, an intake valve fluidly connected to the electronic supercharger, an exhaust valve fluidly connected to an exhaust manifold of the engine, an electrically heated catalyst fluidly connected to the exhaust manifold and positioned in a front end of a catalyst part, and a controller configured to control driving of the electronic supercharger and an opening degree of each of the intake valve and the exhaust valve. The controller controls the electronic supercharger based on a door opening condition in a cold operation and switches the intake valve to an advance state and the exhaust valve to a retard state, thus heating the electrically heated catalyst.

An exhaust aftertreatment system for an internal combustion engine includes an outer casing defining an exhaust flow path for exhaust gases from the internal combustion engine, a selective catalytic reduction unit provided in the exhaust flow path for reducing nitrogen oxides, a urea dosing device for adding urea to the exhaust flow upstream of the selective catalytic reduction unit, and a rotatable mixer device for mixing the urea with exhaust gases upstream of the selective catalytic reduction unit. The exhaust aftertreatment system further comprises an air inlet valve provided upstream of the mixer device for introducing air into the exhaust flow path, and an electric motor arranged for rotating the mixer device to create a suction of air into the exhaust flow path via the air inlet valve.