A method is proposed for regulating a fill level of an exhaust component storage of a catalyst (26) of an internal combustion engine (10), wherein the regulating of the fill level is done by using a system model (100), comprising a catalyst model (102), and wherein uncertainties of measured or model variables influencing the regulating of the fill level are corrected by an adaptation, which is based on signals of an exhaust gas probe (34) arranged at the outlet side of the catalyst (26). The method is characterized in that the adaptation takes multiple pathways (200, 210, 220), wherein signals from different signal regions (260, 280, 300) of the exhaust gas probe (34) situated at the outlet side are processed on different pathways. An independent claim is addressed to a controller designed to carry out the method.

A method and an apparatus including 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, the first signal defining a duty cycle, receive a second signal indicative of a downstream air-fuel equivalence ratio from a second sensor positioned downstream of the intake of the catalyst, adjust the duty cycle based at least in part on the second signal, and provide a fault signal in response to the duty cycle not meeting a duty cycle range for a predetermined period of time. A notification circuit is structured to provide a notification indicating that the second sensor is faulty in response to receiving the fault signal.

A vehicle control apparatus for a vehicle includes a catalyst deterioration diagnosing unit, an engine controlling unit, and a diagnosis start determining unit. The catalyst deterioration diagnosing unit executes a deterioration diagnosis of a catalyst included in an exhaust system of an engine provided in the vehicle. The engine controlling unit controls an air-fuel ratio of the engine to a lean side and thereafter to a rich side during the deterioration diagnosis of the catalyst. The diagnosis start determining unit prohibits the deterioration diagnosis of the catalyst from being executed when a deceleration rate upon deceleration of the vehicle is high, and permits the deterioration diagnosis of the catalyst to be executed when the deceleration rate upon deceleration of the vehicle is low.

When an amount of PM trapped by a GPF is large and a request for regeneration is made, a CPU determines whether an execution condition for executing a temperature increasing process is satisfied. At a point in time t1, at which the execution condition is satisfied, the CPU executes a scavenging process to assign 1 to a condition satisfaction flag Ftr, cause the air-fuel ratio of air-fuel mixture in cylinders #1, #3, and #4 to be the stoichiometric air-fuel ratio, and stop a combustion operation in a cylinder #2. After a point in time t2, which is after a combustion cycle, the CPU executes a temperature increasing process. The temperature increasing process causes the air-fuel ratio of the air-fuel mixture in the cylinders #1, #3, and #4 to be richer than the stoichiometric air-fuel ratio, and stops the combustion operation in the cylinder #2.

A method for operating an internal-combustion engine having an exhaust gas catalyst, a first exhaust gas sensor upstream of the exhaust gas catalyst and a second exhaust gas sensor downstream of the exhaust gas catalyst. A fill level of an exhaust gas component that can be stored in the exhaust gas catalyst is determined using a theoretical catalyst model, into which, as the input value, a signal of the first exhaust gas sensor (a first signal); a signal of the second exhaust gas sensor (a second signal); and a target signal are provided. The target signal corresponds to the signal that would be expected at the determined fill level in the exhaust gas catalyst. The catalyst model is reinitiated when the deviation of the second signal from the target signal exceeds a predetermined threshold value. The fill level is also regulated, and an air-fuel mixture is adjusted.

A method for the onboard diagnosis in a vehicle having a catalytic convertor and a lambda-controlled internal combustion engine in the running operation of the vehicle, includes determining the currently maximum possible oxygen storage capacity of the catalytic convertor as well as a measured temporal duration between the lean spike of the pre-catalyst lambda probe and the post-catalyst lambda probe takes place by means of an OSC diagnosis. The method also includes determining a theoretical residual oxygen content and determining a theoretical temporal duration. When the quotient between the measured temporal duration (Δt) and the theoretical temporal duration (Δt.sub.theo) lies within a predefined range delimited by a first and a second threshold value (SW1; SW2), thus:

[00001]$\mathrm{SW}1\le \frac{\Delta t}{\Delta t_{\mathrm{theo}}}\le \mathrm{SW}2,$

it is determined that the pre-catalyst lambda probe and the post-catalyst lambda probe operate without flaw.

An internal combustion engine control device and a catalyst deterioration diagnostic method according to the present invention control the amount of fuel to be supplied to an internal combustion engine such that the air-fuel ratio of the exhaust on the downstream side of the exhaust purification catalyst is alternately switched between rich and lean, measure the oxygen storage capability of the exhaust purification catalyst during a measurement period within a reversal period of the air-fuel ratio, and diagnose deterioration of the exhaust purification catalyst based on a measurement value of the oxygen storage capability. A time point at which the output of an exhaust sensor indicates that the air-fuel ratio of the exhaust on the downstream side of the exhaust purification catalyst begins to change from a vicinity of a stoichiometric air-fuel ratio to rich or lean is set as the time of end of the measurement period.

An exhaust gas control apparatus for an internal combustion engine includes: a catalyst disposed in an exhaust passage of the engine and configured to be able to occlude oxygen; an air-fuel ratio sensor that detects an air-fuel ratio of an out-flow exhaust gas; and an air-fuel ratio control device that controls an air-fuel ratio of an in-flow exhaust gas to a target air-fuel ratio. The device executes air-fuel ratio reduction control in which the target air-fuel ratio is set to a rich setting air-fuel ratio, and corrects a parameter related to the air-fuel ratio reduction control such that an amount of a reducing gas supplied to the catalyst is decreased when a minimum air-fuel ratio obtained when the detected air-fuel ratio is varied to a rich side is richer than the rich setting air-fuel ratio or an average value of detected air-fuel ratios of the in-flow exhaust gas.

An exhaust gas control apparatus for an internal combustion engine includes: a catalyst disposed in an exhaust passage of the engine and configured to be able to occlude oxygen; an air-fuel ratio sensor that detects an air-fuel ratio of an out-flow exhaust gas; and an air-fuel ratio control device that controls an air-fuel ratio of an in-flow exhaust gas to a target air-fuel ratio. The device executes air-fuel ratio reduction control in which the target air-fuel ratio is set to a rich setting air-fuel ratio, and corrects a parameter related to the air-fuel ratio reduction control such that an amount of a reducing gas supplied to the catalyst is decreased when a minimum air-fuel ratio obtained when the detected air-fuel ratio is varied to a rich side is richer than the rich setting air-fuel ratio or an average value of detected air-fuel ratios of the in-flow exhaust gas.

When an amount of PM trapped by a GPF is large and a request for regeneration is made, a CPU determines whether an execution condition for executing a temperature increasing process is satisfied. At a point in time t1, at which the execution condition is satisfied, the CPU executes a scavenging process to assign 1 to a condition satisfaction flag Ftr, cause the air-fuel ratio of air-fuel mixture in cylinders #1, #3, and #4 to be the stoichiometric air-fuel ratio, and stop a combustion operation in a cylinder #2. After a point in time t2, which is after a combustion cycle, the CPU executes a temperature increasing process. The temperature increasing process causes the air-fuel ratio of the air-fuel mixture in the cylinders #1, #3, and #4 to be richer than the stoichiometric air-fuel ratio, and stops the combustion operation in the cylinder #2.