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 exhaust emission control device for an engine is provided with a first purifying catalyst including an HC adsorbent that adsorbs HC at a low temperature and releases HC at a high temperature and a diesel oxidation catalyst capable of oxidizing HC, a second purifying catalyst including a NOx catalyst capable of storing NOx contained in exhaust, a NOx catalyst regenerator that regenerates the NOx catalyst while raising the temperature of the NOx catalyst, and HC controller that decides whether the amount of adsorbed HC that is HC adsorbed by the HC adsorbent is equal to or more than a preset reference amount and, when the amount of adsorbed HC is decided to be equal to or more than the reference amount, raises the temperature of the first purifying catalyst.

A control apparatus for an internal combustion engine includes an electronic control unit. The electronic control unit is configured to: execute increasing a temperature of an exhaust gas control apparatus at a second temperature increase speed as a regeneration control when the temperature of the exhaust gas control apparatus is in a second temperature range; control the temperature of an exhaust gas control apparatus during an idle operation so as to be equal to or smaller than the temperature of the exhaust gas control apparatus when the internal combustion engine enters an idle operation state as a temperature increase suppression control when the temperature of the exhaust gas control apparatus during a regeneration control is in the second temperature range and the internal combustion engine is in the idle operation state.

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.

A control apparatus for an internal combustion engine is provided. The control apparatus includes a temperature sensor and an electronic control unit. The temperature sensor is configured to detect the temperature of an exhaust gas control apparatus. The electronic control unit is configured to: estimate a sulfuric compound accumulation amount on the exhaust gas control apparatus; and when a specific condition in which the sulfuric compound accumulation amount is equal to or larger than a predetermined accumulation amount and the temperature of the exhaust gas control apparatus is equal to or higher than a predetermined temperature or more is satisfied, control an intake air amount adjuster such that an intake air amount when the specific condition is satisfied is increased as compared to the intake air amount when the specific condition is not satisfied in the same operation state.

An ECU 30 calculates a target temperature of a bed temperature of a DOC 22a under PM regeneration control at each control period by the elements M1 to M9. Among these elements, the estimating section M7 estimates a passing SO.sub.3 amount at each control period by using an inflow SOx amount and a representative temperature. The estimating section M8 estimates a SO.sub.2 reduction rate, which is a ratio of reduction from SO.sub.3 to SO.sub.2 in the DOC 22a. Then, the calculating unit M9 calculates an amount of SO.sub.3 that is allowed to desorb from the DOC 22a as an allowable desorption SO.sub.3 amount at each control period, by using a constrained SO.sub.3 amount which corresponds to a constraint concerning sulfate white smoke, the passing SO.sub.3 amount, and the SO.sub.2 reduction rate.

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.

A controller for an internal combustion engine includes processing circuitry that performs a dither control process on condition that a temperature increase request of a catalyst is made. The processing circuitry operates fuel injection valves so that during the dither control process, one or more cylinders are lean combustion cylinders in a first period and another one or more cylinders are rich combustion cylinders and so that the average value of an exhaust gas-fuel ratio is a target air-fuel ratio in a second period including the first period. The dither control process is restricted in a manner that, on condition that the rich process is performed, the degree of richening of the richest exhaust gas-fuel ratio of exhaust gas-fuel ratios in the cylinders is reduced.

Apparatus for reactivating a sulfur poisoned oxidation catalyst operating in exhaust of a lean burn, methane source fueled combustion device. Reactivation includes desulfation of the poisoned catalyst through a CO supplementation apparatus communicating with the control unit that is adapted to supplement CO content in exhaust reaching the catalyst, while avoiding an overall rich exhaust atmosphere at the catalyst (e.g., an added supply of hydrocarbons to one or more-of the lean burn engine's combustion chambers as by an ECU controlled extra supply of NG 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 exhaust reaching the catalyst while retaining an overall lean state, and a method of assembling an apparatus for reactivating a sulfur deactivated lean burn NG engine catalyst by assembling a CO supplementation apparatus with control unit.