Methods and systems for heating an emission control device are provided. In one example, a method for a vehicle comprises during an engine cold start, heating an emission control device of the engine using a dual heat exchanger to heat secondary air and cool exhaust gas, and further heat secondary air with an electric heater. The method further comprises directing the heated secondary air to each exhaust runner of the engine via individual air injectors to mix with exhaust gas. In this way, an improved mixture of air and exhaust reduces catalyst light-off time and increases conversion efficiency, thereby reducing hydrocarbon emissions during engine cold start.

A method for monitoring a secondary airflow (SAIR) system in an engine includes determining degradation of the SAIR system adding a SAIR to downstream of an engine cylinder exhaust based on a comparison of the SAIR before and after a shutdown of a SAIR pump, the SAIR calculated from a fuel injection amount, an exhaust air-fuel ratio, and an engine intake airflow. In this way, SAIR at the exhaust manifold can be monitored utilizing existing onboard sensors and technology, thereby maintaining OBD and emissions monitoring, reducing engine emissions, and maintaining costs.

Methods and systems for heating an emission control device are provided. In one example, a method for a vehicle comprises during an engine cold start, heating an emission control device of the engine using a dual heat exchanger to heat secondary air and cool exhaust gas, and further heat secondary air with an electric heater. The method further comprises directing the heated secondary air to each exhaust runner of the engine via individual air injectors to mix with exhaust gas. In this way, an improved mixture of air and exhaust reduces catalyst light-off time and increases conversion efficiency, thereby reducing hydrocarbon emissions during engine cold start.

Methods and systems using model based and iterative calculations of mass flow throughout an internal combustion engine system. A secondary air injection valve is provided to selectively allow intake air to pass to the exhaust side of the engine system to aid in exothermic reaction with exhaust gasses exiting the engine for various purposes. The iterative calculations of mass flow include estimation of the mass flow through the secondary air injection valve.

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.

A method for operating an exhaust gas burner that is situated in an exhaust gas system downstream from an internal combustion engine of a motor vehicle during a start phase of the exhaust gas burner, in which the internal combustion engine is not fired. The method includes an incremental increasing of the air mass flow supplied to the exhaust gas burner and an incremental varying of a fuel mass flow supplied to the exhaust gas burner.

An exhaust gas system is provided for a transport refrigeration unit (TRU) engine. The exhaust gas system includes an exhaust system. The exhaust system includes a catalyst operable in a temperature range to catalyze exhaust gas produced in the TRU engine and flown through the exhaust system. The exhaust gas system further includes temperature sensors respectively disposed to sense exhaust gas temperatures upstream of and downstream from the catalyst, at least one of first, second and third valves which are proportionally controllable to moderate amounts of air provided to the TRU engine, fuel provided to the TRU engine and air provided to the catalyst, respectively, and a controller. The controller is configured to compare sensed exhaust gas temperatures with the temperature range and issue a proportional signal to the at least one of the first, second and third valves in accordance with results of the comparison.

An apparatus of purifying exhaust gas of a hybrid vehicle includes an electric supercharger disposed on an air intake line, a post-treatment unit disposed on an exhaust gas line and including an electrically-heated catalyst, an exhaust gas recirculation unit including an exhaust gas recirculation cooler disposed on a recirculation line connecting the post-treatment unit and the intake line and an exhaust gas recirculation valve disposed on the recirculation line, a three-way valve disposed at a position at which the recirculation line diverges into a front end portion and a rear end portion of the intake line, and a controller electrically connected to the three-way valve and configured for controlling the three-way valve connecting the intake line and the recirculation line at the front end portion of the electric supercharger to be selectively opened or closed.

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.

A method for operating a supercharged internal combustion engine. Before a cold start of the engine, an electric drive device of an electrically assisted exhaust-gas turbocharger of the engine is activated such that fresh air is compressed by a compressor of the turbocharger and, in the process, is heated and is conveyed via an open overrun air recirculation valve arranged downstream of the compressor, through a short circuit back to a suction side of the compressor of the turbocharger. A proportion of the air that is heated by way of the short-circuit operation of the compressor is, downstream of the compressor and upstream of a closed throttle flap of the engine, conducted via a secondary air system into an exhaust manifold and from there via a wastegate of the turbocharger into the catalytic converters of an exhaust-gas aftertreatment device of the engine.