A system and method for controlling a temperature of an exhaust gas at an inlet of a selective catalytic reduction system during at least certain low air density conditions. The system may detect an air density value upstream of an internal combustion engine of an engine system, such as, for example, at an inlet of a compressor. Using the detected air density, one of a plurality of relationships between an engine speed and an outputted engine power, as a function of the detected air density value, may be selected for use in determining what combination of engine speed(s) and/or engine power(s) will produce an exhaust gas that is within a target exhaust gas temperature. Using the selected relationship, at least one of the engine speed and the engine power may be adjusted to at least assist in attaining the target exhaust gas temperature.

A vehicle includes: an internal combustion engine; a filter collecting particulate matter contained in exhaust gas of the internal combustion engine; a heater core configured to be able to heat up a vehicle cabin; and an electronic control unit. The electronic control unit is configured to execute regeneration cut control and heating control. The regeneration cut control is a control for regenerating the filter by stopping a fuel supply to the internal combustion engine and supplying oxygen to the filter in a state where an output shaft of the internal combustion engine rotates. The heating control is a control for bringing the internal combustion engine into a combustion state and heating by the heater core. The electronic control unit is configured not to execute the heating control but to execute the regeneration cut control when the heating control is requested and the regeneration cut control is requested.

Methods and systems are provided for regenerating a particulate filter of a vehicle. In one example, a method may include, during a non-engine operating condition, regenerating a particulate filter coupled in an exhaust system downstream of an engine by activating an electric heater of the particulate filter and directing intake air through the particulate filter, the intake air bypassing the engine, and adjusting an electrical load of the electric heater responsive to one or more of exhaust temperature and intake airflow.

Diagnostic systems and methods for detecting leaks in an exhaust gas recirculation (EGR) system of an engine of a vehicle utilize an upstream oxygen (O2) sensor disposed in an exhaust system of the engine upstream from an EGR port of the EGR system and configured to measure an upstream O2 concentration of exhaust gas produced by the engine, a downstream O2 sensor disposed in the exhaust system downstream from the EGR port and configured to measure a downstream O2 concentration of the exhaust gas, and a controller configured to receive the measured upstream and downstream O2 concentrations from the upstream and downstream O2 sensors, respectively, and detect a leak in the EGR system when a difference between the measured downstream and upstream O2 concentrations exceeds a diagnostic threshold.

A combined engine system is disclosed which may help to meet electrical power demand of a common load that can vary in an unpredictable manner. The system comprises at least one primary engine and one or more secondary engines. An after-treatment system is connected to the engines to receive exhaust flow from each of the engines. A controller is configured to operate the system in a first operating mode when only the primary engine is running and a second operating mode when the secondary engines are run together with the primary engine. Exhaust flows from each of the engines are passed through the after-treatment system which allows the after-treatment system to be heated by the exhaust flow of the primary engine before receiving exhaust flows from the secondary engines.

A method for reducing nitrogen oxide emissions of a diesel vehicle. In this context, first state variables of the diesel vehicle are measured with the aid of sensors of the diesel vehicle, and using an arithmetic unit, it is ascertained, as a function of the first state variables, if the nitrogen oxide emissions are exceeding a predetermined threshold, or using the arithmetic unit, it is predicted, as a function of the first state variables, if the nitrogen oxide emissions will exceed the predetermined threshold. If exceedance of the threshold is calculated or predicted, then an intervention in the current torque demand of the diesel vehicle and/or an intervention in the current transmission ratio or setting of a transmission of the diesel vehicle is ascertained by the arithmetic unit; the intervention contributing to a reduction in the nitrogen oxide emissions to a value below the threshold.

An engine exhaust device includes: a first catalyst; a second catalyst; and a connecting member shaped into a tube and forming a part of the exhaust path, and connecting the first catalyst to the second catalyst. A downstream end surface of the first catalyst and an upstream end surface of the second catalyst form a dihedral angle within a range from 60 degrees to 120 degrees. A part of the upstream end surface of the second catalyst is close to and faces a part of a side surface of the first catalyst. On a cross-section including a central axis of the first catalyst and being parallel to a central axis of a second catalyst, a length of the part of the side surface of the first catalyst is longer than or equal to 10% and shorter than 50% of an entire length of the first catalyst.

Methods and systems are provided for partially regenerating a lean NO.sub.x trap in response to an engine shutdown request. In one example, an engine shutdown is delayed so that a low-temperature storing region of the lean NO.sub.x trap is regenerated without regenerating a high-temperature storing region of the lean NO.sub.x trap. A battery charge is replenished during the shutdown, wherein the charge may be consumed during a subsequent engine operation.

Methods and systems are provided for partially regenerating a lean No.sub.x trap in response to an engine shutdown request. In one example, an engine shutdown is delayed so that a low-temperature storing region of the lean No.sub.x trap is regenerated without regenerating a high-temperature storing region of the lean No.sub.x trap.

An internal combustion engine system includes a control system with a monitoring mechanism producing data of engine operating state within a BMEP/speed envelope, and an electronic control unit structured to output a control command to vary at least one of a fuel delivery property or an air delivery property in the engine based on the data. Outputting the control command switches the engine between or among combustion modes that each satisfy different calibration criteria for optimizing aftertreatment function.