A controller alternately repeats a desorption process of desorbing sulfur compound deposited on an NSR catalyst by supplying fuel from a direct injection valve to exhaust gas, and a pausing process of pausing fuel supply from the injection valve to the exhaust gas. The controller executes a cooling fuel addition for adding engine fuel from the addition valve of the exhaust passage to cool the addition valve during execution of the pausing process, and prohibit the cooling fuel addition during execution of the desorption process. The controller calculates a target temperature of the addition valve at the time of start of the desorption process such that the temperature of the addition valve during execution of the desorption process does not exceed an allowable upper limit temperature and calculates the addition amount at the time of cooling fuel addition.

An apparatus for reactivating a sulfur poisoned oxidation catalyst operating in the exhaust of a lean burn, methane source (as in natural gas) fueled combustion device as in an engine. The reactivation includes desulfation of the poisoned catalyst through the use of a CO supplementation apparatus in communication with the control unit that is adapted to supplement the CO content in the exhaust reaching the catalyst, while avoiding an overall rich exhaust atmosphere at the catalyst. An example includes the added supply of hydrocarbons to one or more, preferably less than all, of the lean burn engine's combustion chambers such as by an ECU controlled extra supply of NG (e.g., CNG) to some of the combustion chambers. Also featured is a method for desulfation of an oxidation catalyst of a lean burn CNG engine by supplying excess CO to the exhaust reaching the catalyst while retaining an overall lean state, and a method of assembling an apparatus for reactivating a sulfur deactivated lean burn NO engine catalyst by assembling a CO supplementation apparatus with a control unit.

An exhaust gas control apparatus includes a catalytic device in an exhaust passage, and the catalytic device carrying an NSR catalyst and an oxygen storage agent. A poisoning recovery control section of the catalytic device executes poisoning recovery control and includes: an oxygen storage amount estimation section that estimates an oxygen storage amount of the catalytic device; a determination section that determines timing at which an estimation value of the oxygen storage amount becomes equal to or smaller than an elimination start determination value after a start of elimination processing in the poisoning recovery control as elimination start timing; and a termination timing decision section that decides termination timing of the poisoning recovery control on the basis of a supply amount of a reducing agent to the catalytic device in a period after the elimination start timing during the elimination processing.

An exhaust gas control apparatus includes a catalytic device in an exhaust passage, and the catalytic device carrying an NSR catalyst and an oxygen storage agent. A poisoning recovery control section of the catalytic device executes poisoning recovery control and includes: an oxygen storage amount estimation section that estimates an oxygen storage amount of the catalytic device; a determination section that determines timing at which an estimation value of the oxygen storage amount becomes equal to or smaller than an elimination start determination value after a start of elimination processing in the poisoning recovery control as elimination start timing; and a termination timing decision section that decides termination timing of the poisoning recovery control on the basis of a supply amount of a reducing agent to the catalytic device in a period after the elimination start timing during the elimination processing.

A vehicle control system vehicle control system to remove deposition from the purification system without generating noises and vibrations is provided. The vehicle control system comprises a controller that operates the vehicle having an engine autonomously, and that removes deposition from a purification system. The controller is configured to: obtain an amount of deposition on the purification system; determine a presence of a passenger in the vehicle; and execute the removal control when an amount of the deposition on the purification system exceeds a threshold value. The threshold value includes a first threshold value used when the vehicle is propelled while carrying a passenger, and a second threshold value used when the vehicle is propelled autonomously without carrying a passenger that is smaller than the first threshold value.

An exhaust purification system includes a NOx reduction catalyst which is provided on an exhaust passage of an internal combustion engine, a SOx purging control module for executing a SOx purging control for restoring the NOx reduction catalyst from sulfur poisoning by increasing a temperature of the exhaust gas to a first target temperature at which SOx are desorbed through an injection system control to increase a fuel injection amount, a prohibition module for prohibiting an execution of the SOx purging control according to an operating state of the internal combustion engine, and a temperature retention mode control module for executing a temperature retention mode control for maintaining the temperature of the exhaust gas at a second target temperature which is lower than the first target temperature by controlling the fuel injection amount during a period of time during which the SOx purging control is prohibited.

An exhaust purification system includes: an NOx reduction type catalyst, which is provided in an exhaust passage; an intake air amount sensor, which detects an intake air amount of the internal combustion engine; and a controller, which executes a regeneration treatment that recovers an NOx purification capacity of the NOx reduction type catalyst by switching an exhaust air fuel ratio from a lean state to a rich state by using: an air-system control to reduce the intake air amount; and an injection-system control to increase a fuel injection amount, wherein, in response to a detection value of the intake air amount sensor, the controller changes at least one of a fuel injection timing and the fuel injection amount in the internal combustion engine, in at least one period of switching of: a period of starting the regeneration treatment; and a period of ending the regeneration treatment.

Provided is a method for controlling an exhaust gas treatment system, wherein the system includes an exhaust gas stream supplied by an exhaust gas source to a selective catalytic reduction (SCR) device and a particulate filter device. The method comprises detecting a threshold level of reductant deposits proximate the SCR device, and initiating a selective catalytic reduction device service in response thereto. A threshold level of reductant deposits is detected using a reductant deposit model comprising determining an actual SCR NO.sub.x conversion using measured process variables; and comparing the actual SCR NO.sub.x conversion to a calibrated NO.sub.x conversion value. The calibrated NO.sub.x conversion value is determined using exhaust gas flow and system temperature values which substantially correspond to the process variables under which the actual SCR NO.sub.x conversion was determined. The device service can include increasing the exhaust gas temperature or initiating an active regeneration of the particulate filter device.

An exhaust purification system includes: an NOx reduction type catalyst; an MAF sensor; an SOx purge control unit that uses an air system control having an intake air amount feedback-controlled based on a target intake air amount and an injection system control for a target injection increase amount set based on the target intake air amount, and a fuel injection amount feedback-controlled based on the target injection increase amount; an SOx purge prohibition processing unit that prohibits an SOx purge control; and a warming mode control unit that open-loop controls an air system when the SOx purge control is prohibited, controls the fuel injection amount, and maintains the exhaust gas at a temperature. The SOx purge control unit executes the injection system control by switching the target intake air amount into an actual intake air amount when starting the SOx purge control after a warming mode control is ended.

There is provided an exhaust gas purification system including a lean NOx trap catalyst device which is provided on an exhaust passage of an internal combustion engine, wherein a control unit for controlling the exhaust gas purification system sets a desulfurization temperature Tt which is a target temperature in executing a desulfurization control on the lean NOx trap catalyst device so as to correspond to an sulfur accumulation amount Sa in the lean NOx trap catalyst device. Thereby, the desulfurization control with superior robustness is executed in which the desulfurization process is executed in an ensured fashion while suppressing the lean NOx trap catalyst device from being thermally deteriorated or fused, whereby the exhaust gas purification system for an internal combustion engine, the internal combustion engine and the exhaust gas purification method for an internal combustion engine which can maintain the NOx purification factor high are provided.