Abstract: The invention intends to provide a technology which makes it possible to diagnose with higher accuracy whether or not abnormality occurs in a filter regeneration system causing excessive execution frequency of a regeneration process. The filter regeneration system initiates execution of the regeneration process, incase an estimated particulate matter (PM) accumulation amount at the filter reaches a pre-determined regeneration requiring accumulation amount; or in case the pressure upstream of the filter or the differential pressure across the filter reaches a pre-determined regeneration requiring value, the value being larger than the pressure or the differential pressure corresponding to the regeneration requiring accumulation amount. Then, the diagnosis is carried out based on a ratio of an estimated PM accumulation amount at the initiation of the execution of the regeneration process to the regeneration requiring accumulation amount.

Abstract: A trouble diagnosis device and method for an NOx sensor for determining abnormality of an NOx sensor used in an exhaust gas purification system. The device can perform a trouble diagnosis without forcedly creating a diagnosis mode during operation of an internal combustion engine and without deterioration of drivability or fuel consumption. The device detects the time-lapse variation of the exhaust NOx flow rate suitable for diagnosis in a normal operation mode and determines whether the NOx sensor responds with following this variation.

Abstract: A method for metering a reagent which an emission control device situated in the exhaust duct of an internal combustion engine requires for removing at least one exhaust gas component from the exhaust gas and a device for executing the method are described. The fluid level of the reagent stored in a reagent tank is measured. The measured change in the fluid level is compared to at least one measure for the change in the fluid level calculated as a function of consumption. An error signal is output when the comparison result exceeds a predefined threshold value. This approach enables reliable information to be provided about the fluid level of the reagent in the reagent tank.

Abstract: The degree of deterioration of a catalyst is obtained accurately in cases where a plurality of catalysts is disposed at an exhaust passage of an internal combustion engine. Under the assumption that the degree of deterioration of a catalyst which is disposed at a location upstream of an NOx selective reduction catalyst and has an oxidizing ability is at a predetermined value, the ratio of NO2 in the NOx which inflows into the NOx selective reduction catalyst is estimated; the NOx removal rate of the NOx selective reduction catalyst is calculated a plurality of times at least until a local maximum value is obtained; and the degree of deterioration of the catalyst having an oxidizing ability is determined by comparison between the ratio of NO2 observed when the NOx removal rate of the NOx selective reduction catalyst reaches the local maximum value and a reference value of the ratio.

Abstract: A method for reducing a temperature of an engine component is disclosed. In one example, an air-fuel ratio provided to an engine is adjusted to reduce a temperature of an engine component. The approach may be useful for controlling temperature and emissions from a turbocharged engine.

Abstract: An apparatus for an exhaust gas system includes a main exhaust passage, a main catalytic converter disposed in the main exhaust passage, a bypass exhaust passage, a bypass catalytic converter disposed in the bypass exhaust passage, and a valve configured to open or close a section of the main exhaust passage. The bypass exhaust passage bypasses the main exhaust passage between a branch point of the bypass exhaust passage out of the main exhaust passage and a junction with the main exhaust passage at a upstream side of the main catalytic converter. A first sensor indicates a first air-fuel ratio of exhaust gas in the bypass exhaust passage. A second sensor indicates a second air-fuel ratio of exhaust gas flowing into the main catalytic converter. A controller determines whether the valve in the closed configuration leaks exhaust gas based on the first and second air-fuel ratios of exhaust gas.

Abstract: When a nitrogen oxide storage catalyst is being regenerated, the regeneration may be terminated for example as a result of a premature load change in the engine, which can lead to incomplete emptying of the storage catalyst. The residual filling level which remains in the catalyst following an incomplete regeneration of this nature is used as the starting value for calculation of the filling level during the next storage phase. After incomplete regeneration, the nitrogen oxide conversion rate is initially greater than would be expected, on account of the residual filling level. By taking this increased conversion rate into account when calculating the filling level during the storage phase, it is possible to further improve the accuracy of the calculation.

Abstract: When switching an exhaust throttle valve from full opening to a closed position to warm up an engine, an intake throttle valve is fixed to full opening, an EGR valve is fixed to full closing, and a variable turbo-vane is fixed to a predetermined opening degree to accelerate a gas flow rate from an intake passage to an exhaust passage, a fully opened flow rate is detected and stored by gas flow rate detector, with the exhaust throttle valve being full opening. Then, an instruction is issued to the exhaust throttle valve to switch from the full opening to a closed position, after which a rotation number of the engine is detected, a threshold value is determined based thereon, a closed position flow rate is detected, a flow rate difference relative to the stored fully opened flow rate is determined, and failure of the exhaust throttle valve is judged based on whether the flow rate difference is less than the determined threshold value.

Abstract: An exhaust emission purifier able to suppress overheats of an exhaust emission purifying catalyst and execute fuel addition promptly when fuel addition to the exhaust emission purifying catalyst is requested is provided. In the exhaust emission purifier of an internal combustion engine including exhaust emission purifying catalyst of purifying exhaust emission of an internal combustion engine and a fuel addition valve of adding fuel from upstream of the exhaust emission purifying catalyst, cycles are repeated in order that the exhaust emission purifying catalyst is to be regulated at a target temperature, the cycle being a combination of an addition period during which fuel is added from the fuel addition valve and a halt period during which fuel addition is halted, and the fuel addition valve is manipulated such that the halt period is disposed so as to sandwich the addition period in the cycle.

Abstract: An exhaust component for use with a combustion engine is disclosed. The exhaust component may have a housing at least partially defining an inlet and an outlet, and a treatment device supported by the housing in communication with exhaust passing from the inlet to the outlet. The exhaust component may also have a life indicator permanently associated with at least one of the housing and the treatment device.

Abstract: In an exhaust gas purification system provided with two or more exhaust gas purification devices each having an oxygen occlusion ability arranged in series in an exhaust passage, a technique is provided in which the degradation of each of the exhaust gas purification devices can be detected in a distinguished manner with a simple structure. In an exhaust gas purification system having an NSR and a filter with an oxygen occlusion ability arranged in series from an upstream side, an NSR outflow gas air fuel ratio is estimated based on an NSR inflow gas air fuel ratio and an oxygen occlusion ability in the NSR, and a filter outflow gas air fuel ratio is estimated based on the NSR outflow gas air fuel ratio (filter inflow gas air fuel ratio) and an oxygen occlusion ability in the filter.

Abstract: A system according to the principles of the present disclosure includes a diagnostic execution module and a diagnostic disabling module. The diagnostic execution module diagnoses a fault in at least one of an oxygen sensor and a catalytic converter based on input received from the oxygen sensor. The diagnostic disabling module disables the diagnosing based on at least one of a temperature of the catalytic converter and a mass flow rate of air flowing through the catalytic converter.

Abstract: An exhaust gas purifying apparatus for an internal combustion engine, including a particulate filter provided in an exhaust passage of the engine; a pressure difference sensor for detecting a pressure difference between upstream and downstream side pressures of the particulate filter; an upstream side passage, which connects the pressure difference sensor and an upstream side with respect to the particulate filter of the exhaust passage; and a downstream side passage, which connects the pressure difference sensor and a downstream side with respect to the particulate filter of the exhaust passage. An exhaust gas flow rate is calculated according to an operating condition of the engine. A characteristic of change in the pressure difference, which is detected by the pressure difference detector and corresponds to a change in the exhaust gas flow rate, is detected. An abnormality of the downstream side passage is determined based on the characteristic of change in the pressure difference.

Abstract: A sensor detection controller is used in combination with a capacitive sensor that is mounted on a seat of a vehicle in such a manner that a capacitance of the capacitive sensor changes according to whether the seat is occupied. The sensor detection controller has a fault detection mode and a normal detection mode. The sensor detection controller includes a signal source for applying an amplitude signal to the capacitive sensor, a switch for switching a signal path, through which the amplitude signal is applied, between the fault detection mode and the normal detection mode, a signal detector for detecting a change in a voltage or a current of the amplitude signal when the amplitude signal is applied, and an impedance member connected to the signal path.

Abstract: According to one embodiment, an apparatus for evaluating the condition of a NOx adsorber catalyst (NAC) of an internal combustion engine system includes a rich condition timing module, NAC outlet lambda module, and NAC condition module. The rich condition timing module is configured to accumulate the total time during which exhaust gas exiting the NAC has a lambda value less than 1.0. The NAC outlet lambda module is configured to store NAC outlet lambda values of the exhaust gas while the exhaust gas exiting the NAC has a lambda value less than 1.0. The NAC condition module is configured to evaluate the condition of the NAC based on the total time during which exhaust gas exiting the NAC has a lambda value less than 1.0 and an accumulation of the stored NAC outlet lambda values.

Abstract: A method of monitoring regeneration of a particulate filter is provided. The method includes evaluating whether a regeneration event is based on a fixed threshold condition; selectively setting a pass or fail status based on the evaluating; and generating a message indicating the pass or fail status.

Abstract: A catalyst deterioration determination device for determining deterioration of an exhaust gas purging catalyst arranged in an exhaust passage of an internal combustion engine is disclosed. The determination device forcibly changes an air-fuel ratio of an air-fuel mixture, calculates an oxygen occlusion amount of the catalyst based on an oxygen concentration of the exhaust gas at a downstream side of the catalyst that varies after the forcible changing of the air-fuel ratio, and performs deterioration determination on the catalyst based on the calculated oxygen occlusion amount. The determination device includes a prohibition unit which sets a prohibition period when calculating the oxygen occlusion amount after the increasing correction ends to prohibit calculation of the oxygen occlusion amount immediately after the increasing correction ends. The prohibition unit variably sets the prohibition period to be longer as a total increased amount of fuel during the increasing correction increases.

Abstract: [PROBLEM] To provide an exhaust gas purification system suitable for a construction machine provided with a hydraulic pump driven by an engine.

Abstract: A method for improving the effectiveness of filters by increasing accuracy of an estimate of particulate matter loading remaining in the filter after cleaning. In one embodiment, the disclosed method includes removing soot from the DPF by cleaning, and measuring parameters for a set of predetermined criteria. The amount of soot present in the DPF is then estimated based on delta pressure. The resulting estimated soot load value accounts for the noise factors such as ash loading after extended operation. The value is then used to adjust for future measurements of soot loading in the DPF after subsequent regeneration treatments and/or used to diagnose the effectiveness of the cleaning. The method can also be applied to diagnostics of the DPF. When discrepancies between DPSLE and model-based soot load estimate are observed in healthy regenerations, failure modes such as plugged filter, extreme ash loading or substrate melting can be detected.

Abstract: Method and apparatus for operating an exhaust-gas catalytic converter (21) of an internal combustion engine having at least one cylinder (Z1-Z4) and one exhaust-gas section (4), in which the exhaust-gas catalytic converter (21) and a lambda probe (43) downstream of the exhaust-gas catalytic converter (21) are arranged. A characteristic value which is representative for the NOx concentration is determined as a function of a measured signal (VLS DOWN) of the lambda probe (43).

Abstract: Various methods for and embodiments of an aftertreatment system which includes a catalyst disposed upstream of a particulate filter are provided. In one example, the method includes, conducting soot regeneration of the particulate filter under a selected operating condition, and determining whether a soot regeneration frequency of the particulate filter is greater than a threshold frequency. The method further includes initiating a sulfur regeneration of the aftertreatment system based on the soot regeneration frequency of the particulate filter being greater than the threshold frequency, determining whether the soot regeneration frequency of the particulate filter is less than the threshold frequency after the sulfur regeneration, and conducting non-regeneration operation of the aftertreatment system based on the soot regeneration frequency of the particulate filter being less than the threshold frequency after the sulfur regeneration of the aftertreatment system.

Abstract: The present invention provides for a system for controlling NOx emissions based on the calculation of an error given by the difference between a first measured value obtained from a NOx sensor (7) and a second one estimated from a NOx estimation. Said sensor (7) can be used in an adaptation loop, where an open-loop or closed-loop EGR control system is adapted such that the expected NOx emissions (from the EGR controller) match the ones measured with the NOx sensor under steady-state conditions.

Abstract: To suppress clogging of an injection nozzle that supplies fuel to an exhaust passage of an engine, a controller executes intermittent addition of fuel from the injection nozzle. In executing the intermittent addition, the controller calculates a particulate discharge amount within the exhaust passage based on the engine operation state, and multiplies the exhaust gas temperature by the intake air rate to calculate the exhaust energy. Then, based on the particulate discharge amount and the exhaust energy, the controller calculates the amount of fuel to be added.

Abstract: A reserve torque system comprises a first module and a reserve torque module. The first module generates a first signal a predetermined period before an equivalence ratio (EQR) of an air/fuel mixture supplied to an engine is transitioned from a non-lean EQR to a lean EQR. The reserve torque module creates a reserve torque between when the first signal is generated and when the EQR is transitioned to the lean EQR.

Abstract: An exhaust emission purification system and a related method of control, wherein an exhaust throttle valve is opened if an engine load reaches at least a predetermined first judgment value during execution of forced regeneration control, and generating an alarm of failure of the exhaust throttle valve if the engine load reaches at least a second judgment value which is larger than the predetermined first judgment value.

Abstract: A method for operating a motor vehicle which has a drive and an exhaust system with at least one controllable heating device to be placed in contact with exhaust gas, includes at least the following steps: (a) detecting at least one operating parameter of the exhaust system, (b) determining at least one influential variable of the heating device, (c) comparing the at least one influential variable with a target parameter of the exhaust system, and (d) activating the heating device in such a way that the operating parameter reaches the target parameter. A motor vehicle having a drive and an exhaust system is also provided.

Abstract: A temperature increasing degree of the catalytic outflow exhaust temperature at the time the exhaust air-fuel ratio is changed to the rich side is found in respect to each of a plurality of the catalytic inflow exhaust temperatures. A grade (S) of the temperature increasing degree is found based upon the inflow exhaust temperature and the temperature increasing degree to determine degradation of the catalyst based upon at least one of a maximum value (Smax) of the grade and the inflow exhaust temperature (Tinmax) corresponding to the maximum value. An accurate catalyst degradation diagnosis can be carried out since not only the temperature increasing degree but also the inflow exhaust temperature are taken into account.

Abstract: In an exhaust purification system of an internal combustion engine comprising an exhaust purification device which receives a bad influence from SOX in the exhaust gas and a S trap device arranged upstream of the exhaust purification device, which can store SOX in the exhaust gas, an amount of SOX passing through the S trap device is integrated as an integrated value, each allowance value of the integrated value for each elapsed period from the start time of the use of the S trap device is set, and when the current integrated value exceeds the corresponding allowance value and between a first set period ago and the current time, fuel has been supplied into the fuel tank and engine oil has not been exchanged, it is determined that fuel with a high concentration of sulfur has been supplied into the fuel tank.

Abstract: An internal combustion engine has an exhaust gas catalyst, a first exhaust gas sensor that is arranged in such a manner that it can be used in lambda control, and a second exhaust gas sensor that is arranged in such a manner that it can be used in trim control. A HC quality value (EFF_CAT_HC) which is representative of an oxygen storage capacity of the exhaust gas catalyst is determined depending on a measuring signal (VLS_DOWN) of the second exhaust gas sensor. A NOx correction factor (COR_NOX) is determined depending on the measuring signal (VLS_DOWN) of the second exhaust gas sensor, namely depending on signal portions that are representative of the residual oxygen. A NOx quality value (EFF_CAT_DIAL_NOX) is determined depending on the HC quality value (EFF_CAT_HC) and the NOx correction factor (COR_NOX).

Abstract: In a method for the control of the supplied air/fuel ratio of an internal combustion engine (1) with a catalytic converter (5) which is located in the exhaust gas line (2) with an integrated oxygen reservoir (6), it is proposed that the air/fuel ratio be controlled as a function of at least one parameter of the internal combustion engine (1), at least one parameter of the catalytic converter (5), and/or as a function of the type and amount of the exhaust gas emissions which are currently occurring, in order to optimize the relative degree of filling of the oxygen reservoir (6) which is contained in the catalytic converter (5) for favorable conversion of the exhaust gas emissions. According to the proposal, matching to the current conversion demand and the current conversion performance is enabled and thus overall improved exhaust gas conversion is implemented.

Abstract: A hydraulic driving device for a working machine surely prevents behavior of a single rod double acting cylinder not intended by an operator when discharge pressure of a main pump is raised to raise exhaust gas temperature to temperature required for burning particulate matter. A selector valve 160 interposed between a spool valve 61 and a rod chamber of a single rod double acting cylinder 51 and a section (a filter regeneration time actuation valve 122, a vehicle body controller 150) controlling the selector valve, are provided. A switch control section prevents a flow of oil directed from the rod chamber of the cylinder toward the spool valve by actuating the selector valve by a poppet of the selector valve when a by-pass cut valve 110 is controlled to increase a load of an engine 21 to a degree exhaust gas temperature reaches temperature required for burning particulate matter.

Abstract: In an exhaust gas treatment device in which a diesel oxidation catalyst and a DPF are provided in an exhaust pipe of an internal combustion engine, abnormal combustion in the DPF, occurring when the internal combustion engine varies from a high load condition to a low load condition, poses a problem. To solve this problem, in the present invention, a DPF abnormal combustion causing operation is determined to have occurred when the internal combustion engine shifts from a high rotation or high load operation region ? to a low rotation, low load operation region ? within a set time T1. When it is determined that a DPF abnormal combustion causing operation has occurred, abnormal combustion of PM collected in the DPF is suppressed by fully opening an intake throttle valve 44 in order to increase an exhaust gas flow so that heat is removed by sensible heat of the exhaust gas, thereby cooling a DPF device 52, and continuing a late post-injection in order to reduce an oxygen concentration of the DPF.

Abstract: A DPF accumulation amount estimating apparatus uses an integrated PM accumulation amount estimation logic which combines the difference between an engine PM emission amount and a PM regeneration amount and a DPF differential pressure model, thereby achieving minimized influences of changes in an exhaust gas flow rate and the like with resultant improved estimation accuracy.

Abstract: The invention relates to a diagnosis method for an exhaust gas post-treatment system for the reduction of nitric oxides in the exhaust gas train of an internal combustion engine by means of selective catalytic reduction.

Abstract: A method of introducing a reducing agent into an exhaust stream may include injecting the reducing agent into the exhaust gas stream using a reducing agent injector. The method may further include selectively heating a nozzle of the reducing agent injector to reduce residue on the nozzle.

Abstract: An engine exhaust after-treatment system is provided, which may include a particulate trap configured to remove at least some constituents of the exhaust flowing from an engine through an exhaust system. The system may also include a controller configured to collect in-service data related to an operating parameter indicative of the amount of time the engine operates. In addition, the system may include a memory device attached to the particulate trap and including a memory. The memory may be configured to store usage data indicative of how much time the particulate trap has been used in service. The memory may be configured to communicate with the controller to receive information related to the in-service data collected by the controller and update the usage data in the memory, based on the communication with the controller, to reflect a total amount of time the particulate trap has been in service.

Abstract: A method for correcting an estimated amount of NH3 store within a SCR is described. In one example, SCR efficiency is determined from a NOx sensor output and the estimated amount of NH3 is corrected based on the SCR efficiency. Engine emissions may be reduced via improving the estimated NH3 storage level, at least during some conditions.

Abstract: A method to monitor a particulate filter includes determining an equivalent bypass area corresponding to a difference between a mass flowrate of an exhaust gas feedstream flowing to the particulate filter and a mass flowrate of the exhaust gas feedstream flowing through porous walls of a substrate.

Abstract: An internal combustion engine is provided that performs stoichiometric burn operation under control for providing a stoichiometric air-fuel ratio as basic control for an air-fuel ratio. A particulate filter (PM filter) is provided in an exhaust passage of the engine to trap particulate matter PM contained in exhaust gas. If it is judged that the PM filter will have excessively elevated temperature, fuel cut is prohibited during deceleration. Otherwise, before the prohibition of the fuel cut, the air-fuel ratio of exhaust gas is controlled so that the atmosphere of the PM filter is brought into an atmosphere slightly leaner than the stoichiometric air-fuel ratio.

Abstract: A system for the treatment of exhaust gases includes an engine, an exhaust system, and a controller. The exhaust aftertreatment system is configured to accept exhaust gas from the engine and includes a particulate filter configured to filter particulate matter from the exhaust gas. A controller is configured to determine an actual temperature of the particulate filter during a regeneration process and analyze the actual temperature relative to a temperature deviation threshold. The controller is configured to adjust the temperature deviation threshold in real time based, at least in part, on an operating condition of the engine and a mass flow of the exhaust gas.

Abstract: A particulate matter sensor includes a first detection filter provided in an exhaust gas flow passage and capable of collecting particle matter. A second detection filter is provided on a downstream side of the first detection filter in the exhaust gas flow passage and capable of collecting the particle matter. A first differential pressure detection unit is configured to detect a first differential pressure between pressures of an upstream side and the downstream side of the first detection filter. A second differential pressure detection unit is configured to detect a second differential pressure between pressures of an upstream side and a downstream side of the second detection filter. A particle matter amount detection unit is configured to detect an amount of particle matter based on a detection result of the first differential pressure detection unit and a detection result of the second differential pressure detection unit.

Abstract: A method to diagnose exhaust system malfunction in an electronically controlled internal combustion engine having an exhaust system and including a Selective Catalyst Reducer (SCR) is disclosed. The method may comprise determining ambient barometric pressure; determining a baseline curve of exhaust flow; and monitoring said exhaust flow rate for changes in exhaust flow rate compared to change of exhaust pressure across the SCR to diagnose exhaust system malfunction.

Abstract: The present invention relates to an exhaust emission control device having an NOx adsorbent, and makes it possible to judge whether the performance of the NOx adsorbent is degraded temporarily or permanently. The amounts of NOx and water adsorbed by the NOx adsorbent are measured during an actual operation of an internal combustion engine. A reference line indicating the correlation between a preselected water adsorption amount and NOx adsorption amount is then referenced to determine a reference value y0 of the NOx adsorption amount that corresponds to a measured value x1 of the water adsorption amount. Next, a measured value y1 of the NOx adsorption amount is compared against the reference value y0 to output a signal in which the result of the comparison is reflected.

Abstract: An after-treatment device that includes a diesel particulate filter (DPF) requiring periodic regeneration includes a sensor providing a signal indicative of a soot accumulation and at least one device providing an operating parameter indicative of a work mode of the machine. A controller determines a soot loading of the DPF based least partially on the soot signal, and a readiness level based on the operating parameter. A soot level trigger is determined based on a time period since a regeneration was completed and the readiness level, and a debounce time period is determined based on the soot loading and the readiness level. The controller is configured to initiate a regeneration event of the DPF when the debounce time period has expired while the soot loading exceeds the soot level trigger.

Abstract: The invention relates to a method for the voltage-controlled performance regulation of the heating of an exhaust-gas probe in the exhaust system of an internal combustion engine. The aim of the invention is to provide a method in which the operating temperature of the probe is achieved in the shortest possible time without damage to the probe. To achieve this, the heating voltage during the heating phase of the probe is rapidly brought up to a high temperature in a start phase in relation to a subsequent phase, or a dramatic leap in temperature is achieved, preferably up to the full operating voltage and the heating voltage is then continuously or quasi-continuously reduced.

Abstract: In an exhaust purification system having a urea addition device adding a urea aqueous solution to an NOx catalyst of selective reduction type provided in an exhaust passage in an internal combustion engine, a sensor detecting an ammonia concentration is provided at the downstream side of the NOx catalyst. During fuel cut, a predetermined amount of urea aqueous solution is added. Then, based on a sensor output obtained at this time, an abnormality in at least one of the urea addition device and the urea aqueous solution is detected. The addition of the urea aqueous solution during the fuel cut prevents reactive consumption between urea and NOx. The sensor output corresponding to the amount of the urea aqueous solution is obtained. This output condition is compared with a normal one to allow determination of whether or not an appropriate amount of urea aqueous solution of appropriate quality has been added.

Abstract: A system and method for diagnosing operation of a NOx adsorber catalyst are disclosed. An operating temperature of the catalyst is monitored, and when it exceeds a catalyst desulfation temperature threshold that occurs when the catalyst undergoes a desulfation event, a control circuit determines an oxygen storage capacity of the catalyst as a function of at least an oxygen concentration of exhaust gas exiting the catalyst. The control circuit may further determine the oxygen storage capacity as a function of an oxygen concentration of exhaust gas entering the catalyst. The control circuit may further determine the oxygen storage capacity as a function of a mass flow rate of fresh air entering the internal combustion engine that produces the exhaust gas. The oxygen storage capacity may be mapped to catalyst aging information such as, for example, a remaining useful life of the catalyst.

Abstract: A catalyst degradation determining method includes the steps of: controlling an upstream-of-catalyst air-fuel ratio occurring upstream of a first catalyst to an air-fuel ratio that is rich of a stoichiometric air-fuel ratio so that first and second catalysts store oxygen up to a maximum storage amount of oxygen. The method then includes the steps of controlling the upstream-of-catalyst air-fuel ratio to a first lean air-fuel ratio until an output of a downstream-of-first-catalyst sensor indicates a lean air-fuel ratio, and then to a second lean air-fuel ratio and that has a value that is determined in accordance with an oxidizing-reducing capability index value, until a time point when an output of a downstream-of-second-catalyst air-fuel ratio sensor indicates an air-fuel ratio that is lean.

Abstract: A method of operating an internal combustion engine having a reductant delivery and storage system in an emission control system, comprising of correlating a change in a monitored operating condition with a refill event to determine whether a reductant-diluting substance has been added to the reductant storage system; and limiting vehicle operation based on the correlation.

Abstract: An exhaust gas purification system includes: a catalyst (3) provided in an exhaust gas passage of an internal combustion engine (1) and having a carrier containing a basic oxide and platinum carried on the carrier; a catalyst (4) for purifying NOx; and oxygen supply means (2).