Methods and systems are provided for continually monitoring a functionality of an exhaust catalyst based on roll-down of a monotonically decreasing catalyst activity parameter representing catalyst storage capacity. Catalyst degradation may be indicated responsive to the estimate of catalyst storage capacity lowering below a threshold. Engine operating parameters may be adjusted based on a current level of catalyst storage capacity.

Aspects of the present invention relate to a controller (104) and method (400) for controlling operation of an internal combustion engine (101). The controller (104) is configured to: receive a first request signal indicative of a request to stop fuel being supplied to the engine (101), and cause an intake valve (301) of a cylinder (103) of the internal combustion engine (101) to remain closed during the current revolution of the internal combustion engine (101) and revolutions of the internal combustion engine (101) immediately following the current revolution of the internal combustion engine (101) in dependence on at least one of: the intake valve (301) being closed at the time of receiving the first request signal; or a next opening of the intake valve having not been scheduled. The controller (104) is also configured to cause injection of fuel into the cylinder (103) and subsequently cause the intake valve (301) to remain closed during revolutions of the internal combustion engine (101) immediately following a next closing of the intake valve (301), in dependence on at least one of: the intake valve (301) being open at the time of receiving the first request signal; and a next opening of the intake valve (301) having already been scheduled at the time of receiving the first request signal and said next opening of the intake valve (301) is to be performed.

Methods and systems are provided for reducing air flow to an emission control device during a fuel shut-off event. In one example, a method may include adjusting a timing of an exhaust valve and a timing of an intake valve of a cylinder during the fuel shut-off event using a common actuator. The actuator may include a planetary gear system configured to rotate a first portion of a camshaft in a first direction and a second portion of the camshaft in a second, opposite direction.

When the air fuel ratio dither control is carried out, an air fuel ratio of a mixture in each of one or more lean cylinders and one or more rich cylinders is controlled in a feedback manner based on an average value of a detected value of an air fuel ratio sensor, so that an average value of an air fuel ratio of exhaust gas flowing into the three-way catalyst becomes a predetermined target exhaust gas air fuel ratio. At this time, the air fuel ratio dither control is carried out, by setting at least a cylinder with the highest gas impingement intensity in a cylinder group of an internal combustion engine as the one or more lean cylinders.

When the air fuel ratio dither control is carried out, an air fuel ratio of a mixture in each of one or more lean cylinders and one or more rich cylinders is controlled so that an average value of an air fuel ratio of exhaust gas flowing into the three-way catalyst becomes a predetermined target exhaust gas air fuel ratio. At this time, the air fuel ratio dither control is carried out by setting, as the one or more rich cylinders, at least a cylinder for which a degree of uniformity of the flow speed distribution of exhaust gas, which is a degree of uniformity of the flow speed distribution of exhaust gas discharged from that cylinder on a cross section of the three-way catalyst, is the lowest in the cylinder group of an internal combustion engine.

A control apparatus for an internal combustion engine for adjusting an amount of air passing through a catalyst during fuel cut-off operation of the internal combustion engine, the temperature of the catalyst is caused to rise, when the fuel cut-off operation of the internal combustion engine is carried out in a state where the temperature of the catalyst is low. The apparatus is constructed such that in cases where the fuel cut-off operation is carried out in a state where the temperature of the catalyst is relatively low but equal to or higher than an activation temperature thereof, the amount of air passing through the catalyst is made larger in a period of time in which the catalyst becomes a rich atmosphere immediately after the start of the fuel cut-off operation, in comparison with a subsequent period of time in which the catalyst becomes a lean atmosphere.

A method and device for controlling a supercharged internal combustion engine is disclosed. An oxygen charge of a catalytic converter of the internal combustion engine is determined. A valve overlap of the internal combustion engine is increased from a lower valve overlap value to an upper valve overlap value. Increasing the valve overlap and/or for at least one phase of the increase, a control value for increasing an air-fuel ratio in at least one cylinder of the internal combustion engine is reduced as a function of the determined oxygen charge.

An apparatus includes a processing circuit structured to receive a first signal indicative of an upstream air-fuel equivalence ratio from a first sensor positioned upstream of an intake of a catalyst, receive a second signal indicative of a downstream air-fuel equivalence ratio from a second sensor positioned downstream of the intake of the catalyst, determine an actual oxygen storage capacity of the catalyst based at least in part on the received first signal and the received second signal, compare the actual oxygen storage capacity to a maximum storage capacity, and provide a fault signal in response to the actual oxygen storage capacity exceeding the maximum storage capacity. The apparatus also includes a notification circuit structured to provide a notification indicating that the second sensor is faulty in response to receiving the fault signal.

A method comprising adjusting a fuel injection amount based on a fractional oxidation state of a catalyst, the fractional oxidation state based on reaction rates of grouped oxidant and reductant exhaust gas species throughout a catalyst and a low-dimensional physics-based model derived from a detailed two-dimensional model to obtain a one-dimensional model averaged over time and space that accounts for diffusion limitations in the washcoat and accurately predicts emissions during cold start.

An internal combustion engine mounted on a vehicle includes an exhaust passage provided with a catalyst. A controller for the internal combustion engine includes a processor. The processor is configured to perform an auto-stopping process on the engine when the engine is idling, perform an auto-restarting process on the engine when the engine is automatically stopped, correct an amount of fuel injected into the engine so that the fuel injection amount of the engine is increased by a correction amount after the auto-restarting process is started, and change the correction amount in accordance with an amount of oxygen stored in the catalyst at a point of time when the auto-stopping process is started.