A system and method for monitoring the temperature in a vehicle after-treatment system is provided. The system includes one or more temperature sensors positioned in the vehicle after-treatment system and an electronic control unit (ECU) configured by programming instructions encoded in computer readable media to execute a method. The method includes monitoring the temperature presented by the one or more temperature sensors, executing a lower oxygen combustion strategy for a slower exothermic reaction when the temperature exceeds a first threshold level, and deactivating the lower oxygen combustion strategy when the temperature drops below a second threshold level.

Provided is a control device of a hybrid vehicle powered by an internal-combustion engine and a motor, wherein a catalyst that purifies exhaust gas is located in an exhaust passage of the internal-combustion engine, and the control device comprises: a learning unit configured to, during operation of the internal-combustion engine, learn a parameter for controlling a rotation speed of the internal-combustion engine so that a rotation speed of the internal-combustion engine during idling operation is equal to a target rotation speed; and a controller configured to stop the internal-combustion engine when a state where a correction amount of the parameter to cause the rotation speed during idling operation to be equal to the target rotation speed is equal to or greater than a predetermined value continues for equal to or greater than a predetermined time period, the correction amount being obtained by learning by the learning unit.

An exhaust gas control apparatus includes a first catalyst, a filter, and an electronic control unit. The electronic control unit is configured to alternately execute lean control and rich control multiple times. The lean control is control for, over a period longer than a period from when a target air-fuel ratio is set to a predetermined lean air-fuel ratio until an air-fuel ratio of exhaust gas flowing out from the first catalyst becomes greater than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined lean air-fuel ratio. The rich control is control for, over a period longer than a period from when the target air-fuel ratio is set to a predetermined rich air-fuel ratio until the air-fuel ratio of exhaust gas flowing out from the first catalyst becomes smaller than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined rich air-fuel ratio.

Disclosed are a method of controlling a water injector for preventing damage to a catalyst for exhaust gas purification and an engine driven by the method. A method of controlling the operation of an injector for injecting water into the combustion chamber of an engine to which a turbo system for increasing the amount of air by compressing air has been applied includes a catalyst state determination step of determining the danger condition of a catalyst for exhaust gas purification by detecting the state of the catalyst, a water injection amount calculation step of calculating a water injection flow value F1 at which a temperature of exhaust gas drops to a preset temperature when the catalyst is in the danger condition, and a water injection step of performing the waterjet operation of a water injector based on the water injection flow value calculated in the water injection amount calculation step.

A fuel injection controller updates an air-fuel ratio learning value such that the amount of correction of a fuel injection amount according to an air-fuel ratio feedback correction value approaches zero. Further, the fuel injection controller makes an update rate of the air-fuel ratio learning value lower when the variation among respective-cylinder correction values, which are set for the respective cylinders in order to differentiate air-fuel ratios of a plurality of cylinders, is great than when the variation among the respective-cylinder correction values of the cylinders is small.

When the temperature of the exhaust gas flowing into an NSR catalyst exceeds a specific threshold temperature that is determined on the basis of the cetane number of fuel in such a way that the specific threshold temperature is set lower when the cetane number of the fuel is low than when it is high, fuel is supplied to the exhaust gas by fuel supply device to perform an NO.sub.X reduction process for the NSR catalyst. If the quantity of heat generated in the NSR catalyst per unit time is smaller than a specific value while the NO.sub.X reduction process is being performed, the NO.sub.X reduction process in progress is suspended, and the NO.sub.X reduction process is performed later on when the temperature of the exhaust gas flowing into the NSR catalyst exceeds an updated threshold temperature higher than the specific threshold temperature.

A system and method for monitoring the temperature in a vehicle after-treatment system is provided. The system includes one or more temperature sensors positioned in the vehicle after-treatment system and an electronic control unit (ECU) configured by programming instructions encoded in computer readable media to execute a method. The method includes monitoring the temperature presented by the one or more temperature sensors, executing a lower oxygen combustion strategy for a slower exothermic reaction when the temperature exceeds a first threshold level, and deactivating the lower oxygen combustion strategy when the temperature drops below a second threshold level.

When switching an operation mode from a stoichiometric mode to a lean mode, a rich spike that supplies excessive fuel relative to a theoretical air-fuel ratio is executed. If the temperature of the SCR is greater than or equal to an upper limit temperature at a time of the switching, after execution of the rich spike, the switching to the lean mode is executed after executing transient control that makes the EGR rate higher than EGR rate in the lean mode and makes the in-cylinder air-fuel ratio an air-fuel ratio between the theoretical air-fuel ratio and the air-fuel ratio in the lean mode.

A cooling time computing unit computes, based on a temperature detected by a temperature detection unit, a cooling time during which an injection unit is cooled by driving of an engine. A notification control unit uses a notification unit to notify an operator of a necessity of cooling before the engine is stopped, during the cooling time computed by the cooling time computing unit.

A method of operating a Selective Catalytic Reduction on Diesel Particulate Filter or SDPF is disclosed. During a SDPF regeneration; temperature values are obtained for the SDPF inlet and SDPF outlet. The temperature values are used to calculate a rate of increase of SDPF outlet temperature and a rate of increase of SDPF inlet temperature. A ratio between the rate of increase of SDPF outlet temperature values and the rate of increase of SDPF inlet temperature values is calculated, and if the ratio is greater than a threshold thereof, the exhaust gas composition is modified in some manner.