A vehicle (1) is a hybrid vehicle including a traveling mode to travel only with the driving force of a drive motor (5). Vehicle (1) is mounted with an internal combustion engine (10) capable of being operated at an air-fuel ratio leaner than the theoretical air-fuel ratio. The operation of internal combustion engine (10) is controlled by a control unit (41). Control unit (41) is configured to determine whether to stop internal combustion engine (10) in an operation state, in consideration of the NOx adsorption ratio of a downstream-side exhaust purification catalyst (33) provided in an exhaust passage (31) of internal combustion engine (10).

A control system for a vehicle, the control system having one or more controllers, the control system being arranged to: determine a likelihood of a NOx adsorber trap of a vehicle requiring purging; determine an efficiency of purging the NOx adsorber trap; determine an operating efficiency of a selective catalyst reduction system of the vehicle; determine a schedule for purging of the NOx adsorber trap of the vehicle in dependence on the likelihood of the NOx adsorber trap requiring purging, the efficiency of purging the NOx adsorber trap, and the operating efficiency of the selective catalyst reduction system; and control purging of the NOx adsorber trap according to the schedule.

Control of a spark ignited internal combustion in response to an exhaust manifold pressure measurement of an engine is disclosed. An engine out NOx amount for at least one cylinder is determined at least in part in response to the exhaust manifold pressure measurement and a brake mean effective pressure of the at least one cylinder. An operating condition of the engine is adjusted in response to the engine out NOx amount.

Methods and systems are provided for a NO.sub.x sensor. In one example, a method includes heating a NO.sub.x sensor during a vehicle off in response to a cumulative heat energy applied to the NO.sub.x.

A system and method of integrating an engine having dynamic skip fire control with an exhaust gas recirculation system in a turbocharged internal combustion engine is described. An engine control system determines an appropriate firing pattern based at least in part on a desired exhaust gas recirculation flow rate. Signals from sensors in the intake manifold and exhaust system may also be used as part of a feedback loop to determine a desired exhaust gas recirculation flow rate.

Methods and systems are provided for increasing EGR delivered to an engine. In one example, a method may include determining an EVO timing set point and an external EGR setpoint in parallel, based on an inverse model. The EVO timing may be adjusted based on a combination of the EVO timing setpoint and an EGR cylinder balancing feedback loop, thereby varying internal EGR to the engine to supplement external EGR.

The disclosure relates to a self-adaptive oil spraying control system and method for a biodiesel engine. The control system includes an exhaust pipe, a gas sensor, a control module and an oil sprayer, wherein the exhaust pipe is connected to the oil sprayer, the gas sensor is mounted in the exhaust pipe, and the gas sensor and the oil sprayer are connected to the control module respectively. According to the control method, a main spray advance angle of the engine is subjected to closed-loop control directly through comparison between an idling steady state NO.sub.x emission signal and an idling steady state NO.sub.x emission value of pure diesel when the engine uses the biodiesel, so that emission of NO.sub.x in the exhaust is reduced. Compared with the prior art, the disclosure has the advantages of no need of detecting a biodiesel ratio, high efficiency, good effect and the like.

Various embodiments include a method for operating an internal combustion engine with a three-way catalytic converter with lambda control, comprising: monitoring a NO.sub.x sensor for a lambda value downstream of the converter; setting a threshold value determining a lambda setpoint value upstream of the converter using the difference between the setpoint value of the electrical signal and the measured electrical signal if the signal is below the threshold; if above the threshold value, determining the lambda setpoint value upstream of the converter using the difference between a NH.sub.3 setpoint value of the NO.sub.x sensor and the measured NH.sub.3 signal of the NO.sub.x sensor; and if the measured NH.sub.3 concentration is higher than the NH.sub.3 setpoint value, increasing the lambda setpoint value upstream of the converter and, if the measured NH.sub.3 concentration is lower than the NH.sub.3 setpoint value, reducing the lambda setpoint value upstream of the converter.

A method for regulation of an internal combustion engine with an SCR catalytic converter in which the operating point of the engine is predefined by an engine control unit and the operating point of the catalytic converter is predefined by an SCR control unit. An overall system quality measure is calculated by an optimizer in accordance with fed back values of the engine control unit and fed back values of the SCR control unit, by changing the default values for the engine control unit and the SCR control unit, the optimizer minimizes the overall system quality measure for a prediction horizon regarding operating costs. On the basis of the minimized overall system quality measure the optimizer sets the default values for the engine control unit and the default values for the SCR control unit as decisive for setting the operating point of the engine and the catalytic converter.

An internal combustion engine comprises a filter and is configured to enable attachment of a secondary air feed system feeding air into exhaust gas flowing into the filter. A control device of the engine is configured, in the PM removal control for removing particulate matter deposited on the filter, to perform temperature raising processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body 1 is a rich air-fuel ratio and for feeding air from the secondary air feed system, and to perform regeneration processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body is a stoichiometric air-fuel ratio and for feeding air from the secondary air feed system so that the air-fuel ratio of the exhaust gas flowing into the filter is a lean air-fuel ratio.