A method of maintaining a temperature of an aftertreatment system of a vehicle, the method including: operating, by a controller, a retarder reducing driving force of a propeller shaft of the vehicle in response to a retarder operation request signal; operating, by the controller, a jake brake device which discharges a fuel-air mixture compressed in an explosion stroke of the engine to an exhaust pipe and decreases revolutions per minute (RPM) of the engine or an exhaust brake device which blocks a discharge of the exhaust gas of the engine to a rear end of the exhaust pipe and decreases the RPM of the engine, in order to remove the output error value; and controlling, by the controller, the engine so that an amount of exhaust gas introduced into the aftertreatment system is decreased.

A method of operating an engine is provided. The method includes determining a temperature and a pressure of intake air, and a temperature and a pressure of exhaust generated by the engine. The method includes determining a work performed by the engine based at least on an engine speed of the engine, and determining heating losses of the engine. The method includes determining an enthalpy of the intake air based at least on the work, the heating losses, a heating value of a fuel used for combustion within the engine, and the temperature and the pressure of the exhaust. The method includes determining a humidity value of the intake air based on the enthalpy, temperature and pressure of the intake air and determining an amount of NOx based on the humidity value. The method further includes controlling an operation of the engine based on the determined amount of NOx.

A vehicle and method reduce heating of a particulate filter during a regeneration event in response to an accelerator pedal tip-out and particulate filter temperature exceeding or anticipated to exceed a threshold by fueling the engine to reduce oxygen in the exhaust flowing to the particulate filter. An electric machine may be operated as a generator charging a battery to compensate or offset torque produced by the fueling of the engine. The current or anticipated particulate filter temperature may be estimated by a soot combustion model for a current regeneration event and/or a future regeneration event based on soot loading of the particulate filter.

A method for operating an internal combustion engine having a motor and an exhaust gas aftertreatment system having an exhaust gas aftertreatment component, wherein exhaust gas formed in the motor during combustion of fuel is guided via the exhaust gas aftertreatment system for cleaning, includes: determining an exhaust gas actual value that depends upon an actual value of a nitrogen dioxide fraction in the exhaust gas upstream of the exhaust gas aftertreatment component; and changing at least one operating parameter for the motor such that the actual value of the nitrogen dioxide fraction is brought closer to a corresponding reference value for the nitrogen dioxide fraction.

Methods and systems are provided for reducing emissions during an engine cold start. In one example, a method may include, during emission control device heating, initiating combustion in a cylinder via a spark plug directly coupled to the cylinder and providing secondary air via a turbulent jet ignition system. In this way, an amount of hydrocarbons in feedgas provided to the emission control device prior to the emission control device reaching its light-off temperature may be reduced.

Methods and systems are provided for accurately inferring an exhaust temperature during steady-state and transient vehicle operation based on the duty cycle of an exhaust gas sensor heating element. A steady-state temperature is inferred based on an inverse of the duty cycle, and then adjusted with a transfer function that compensates for transients resulting from changes in vehicle speed, and load, and for the occurrence of tip-in and tip-out events. The inferred temperature can also be compared to a modeled temperature to identify exhaust temperature overheating conditions, so that mitigating actions can be promptly performed.

A method of adaptively sampling data to determine the start of injection in a solenoid actuated valve of a fluid injector includes, in an operating cycle or portion thereof of the valve, sampling the signal of current through a solenoid of the valve at sampling points having a pre-defined interval therebetween. At each sampling point, determining the value of the first derivative of current and detecting the sampling point at which the first derivative achieves a maximum as the start of injection. Values of the first derivative of the sampling points immediately preceding and immediately following the start of injection are determined. In a subsequent operating cycle, synchronisation of sampling is altered to shift sampling times depending on the values of the first derivative of the sampling points immediately preceding and immediately following the start of injection.

An exhaust-gas purification system and method are provided for an internal combustion engine having an NOx storage catalytic converter and a downstream SCR catalytic converter. The NOx storage catalytic converter can be supplied in a first operating mode with an oxidizing exhaust gas and in a second operating mode with a reducing exhaust gas. A third operating mode is provided between the first operating mode and the second operating mode, in which an exhaust gas which has a lower content of oxidizing constituents than the first operating mode and a lower content of reducing constituents than the second operating mode can be supplied to the NOx storage catalytic converter to improve NH.sub.3 production at the start of converter regeneration.

Systems and methods are described for coordinating the regeneration of a gasoline particulate filter to a time duration when engine output falls below a predetermined load threshold selected to indicate a low power state of the engine. In one particular example, the engine is configured to adjust engine operations to regenerate the particulate filter responsive to engine output falling below a predetermined low power threshold, the regeneration further based on an estimated duration that the output falls continuously below the low power threshold. The system and methods described advantageously allow for either full or partial regeneration events to be performed based on the estimated duration of the engine output below the low power threshold.

A method is disclosed for operating an aftertreatment system having a diesel particulate filter of an internal combustion engine of an automotive system. A regeneration event of the diesel particulate filter is started. The presence of an object ahead of the automotive system is detected. A value of a deceleration that the automotive system should perform in order to avoid a collision with the object is determined. A temperature of the diesel particulate filter is reduced if the value of the deceleration is greater than a first predetermined threshold value.