An exhaust gas purification system for vehicle includes: a housing disposed on an exhaust pipe to receive a exhaust gas discharged from an engine and to exhaust the exhaust gas passed rearward; a front end catalyst disposed in the housing to purify the exhaust gas flowing into the housing through a front end of the housing; a rear end catalyst disposed in the housing to purify the exhaust gas passing through the front end catalyst before the exhaust gas flows out to a rear end of the housing; and a controller connected to the exhaust pipe at a front end of the housing to control a concentration of unburned fuel contained in the exhaust gas flowing into the housing.

A filling of an exhaust gas component storage of a catalytic converter is regulated. An actual fill level of the exhaust gas component storage is ascertained using a first system model, and a base lambda setpoint value for a first control loop is predefined by a second control loop. An initial value for the base lambda setpoint value is converted into a fictitious fill level, the fictitious fill level being compared with a setpoint value for the fill level output, and the base lambda setpoint value being iteratively changed as a function of the comparison result, if a difference between the setpoint value for the fill level and the fictitious fill level is greater than a predefined degree. The base lambda setpoint value is not changed if no difference exists between the setpoint value for the fill level and the fictitious fill level.

A catalyst degradation detection apparatus includes an air-fuel ratio detector disposed downstream of a catalyst and configured to detect an air-fuel ratio of exhaust gas flowing out from the catalyst, and an electronic control unit configured to control an air-fuel ratio of inflow exhaust gas flowing into the catalyst and determine whether the catalyst is degraded. The electronic control unit is configured to execute degradation determination control that brings the air-fuel ratio of the inflow exhaust gas to an air-fuel ratio leaner or richer than a stoichiometric air-fuel ratio. The electronic control unit is configured to determine whether precious metal of the catalyst is degraded based on the air-fuel ratio detected by the air-fuel ratio detector when an oxygen storage amount of the catalyst is varying in the degradation determination control.

A catalyst deterioration detection system 1 comprises an air-fuel ratio sensor 41, a current detection device 61, a voltage application device 60, a voltage control part 71, an air-fuel ratio control part 72 and a deterioration judging part 73. The air-fuel ratio control part executes fuel cut control, and, after the fuel cut control, executes rich control. The voltage control part, if judging that the air-fuel ratio of the outflowing exhaust gas has reached the stoichiometric air-fuel ratio when setting the applied voltage to a first voltage in a limit current region during the rich control, changes the applied voltage from the first voltage to a second voltage in a limit current region. The deterioration judging part judges the degree of deterioration of the catalyst based on the output current of the air-fuel ratio sensor when the applied voltage is set to the second voltage.

A method and a control device for regulating a modeled fill level of an exhaust gas component reservoir of a catalytic converter of an internal combustion engine. Regulation of the modeled fill level is accomplished using a system model. An actual maximum storage capacity of the catalytic converter for the exhaust gas component is ascertained during operation of the internal combustion engine and is taken into consideration in regulating the modeled fill level.

A method for regulating filling an exhaust gas component (EGC) storage of a catalytic converter (CC) in the exhaust gas (EG) of an internal combustion engine. An actual fill level (AFL) of the EGC storage is ascertained using a first system model (FSM), to which signals of a first EG sensor projecting into the EG flow upstream from the CC and detecting a concentration of the EGC and a second EG sensor, downstream from the CC and exposed to the EG, are fed. A base lambda setpoint value for a first control loop (CL) is predefined by a second CL, which is adjusted to the AFL using the AFL ascertained using the FSM when the voltage of the second EG sensor indicates a breakthrough of rich/lean EG downstream from the CC and an excessively low/high AFL of the EGC storage. Also described is a control unit to perform the method.

The present disclosure relates to assessing the intake air flow of industrial engines. For an industrial engine that receives vent gas added to intake air for combustion, a gas concentration sensor is used to measure a concentration of a particular gas, e.g. methane, in the intake air. An amount of the methane component in the intake air flowing to the engine that was added by the vent gas can be determined from the measured concentration of methane in the intake air and a flow rate of the intake air. The intake air flow rate may be directly measured, or calculated using instrumentation which may already be in place for engine air-to-fuel ratio control.

A method of estimating the oxygen storage capacity of a catalyst includes providing an engine system having an internal combustion engine and an exhaust system having a catalyst and an oxygen sensor, providing a three-way catalyst observer model having a Kalman filter and a three-way catalyst kinetic model, estimating a three-way catalyst next time step state and a modeling error, linearizing the three-way catalyst observer model, filtering the estimated three-way catalyst next time step state, and calculating a covariance.

In order to detect the degree of deterioration of one catalyst with a simple configuration, a catalyst deterioration judging device for an internal combustion engine includes an upstream catalyst disposed in an engine exhaust passage, a downstream catalyst disposed in the engine exhaust passage downstream of the upstream catalyst, an inflow air-fuel ratio sensor for detecting the air-fuel ratio of an inflow exhaust gas to the upstream catalyst, an outflow air-fuel ratio sensor for detecting the air-fuel ratio of an outflow exhaust gas from the downstream catalyst, and an electronic control unit. The maximum oxygen storage amount of the upstream catalyst is detected based on the output of the inflow air-fuel ratio sensor and the output of the outflow air-fuel ratio sensor when the upstream catalyst is in the active state and the downstream catalyst is in the inactive state.

A method for controlling a filling level of an exhaust gas component accumulator of a catalytic converter in the exhaust gas of an internal combustion engine where an actual filling level of the accumulator is determined with a first catalytic converter model. The method includes forming a lambda setpoint is formed, wherein a predetermined target fill level is converted into a base lambda setpoint via a second system model reverse of the first catalytic converter model, a deviation of the actual fill level from the predetermined target fill level is determined and processed to a lambda setpoint correction value via a fill level control unit, a sum of the base lambda setpoint value and the lambda setpoint value correction value is formed, and said sum is used to form a correction value, with which fuel metering to at least one combustion chamber of the internal combustion engine is influenced.