There is provided: a NOx occlusion reduction-type catalyst that is provided in an exhaust passage of an internal combustion engine, occludes NOx in exhaust when the exhaust is in a lean state, and reduces and purifies the occluded NOx when the exhaust is in a rich state; an exhaust injector that is provided in the exhaust passage and is positioned further upstream than the NOx occlusion reduction-type catalyst; a NOx-purging control unit that performs NOx purging of reducing and purifying the NOx occluded in the NOx occlusion reduction-type catalyst by lowering the exhaust to a prescribed target lambda by fuel injection by the exhaust injector; and a NOx-purging-prohibition processing unit that inhibits performance of the NOx purging in a case where the exhaust cannot be lowered to the target lambda even if the fuel injection is performed at a maximum limit injection amount of the exhaust injector.

Methods and systems for calculating a plurality of aging factors in a system operating an engine. The calculated aging factors may include one or more of fuel injector drift, exhaust gas recirculation valve obstruction, and mass air flow sensor bias. Mass flow throughout the system, and pressures and temperatures within the system, are observed in an approach that relies on mass preservation concepts to estimate fuel injector drift, exhaust gas recirculation valve obstruction, and mass air flow sensor bias.

In a fuel injection controller, a first throttle opening TH0 is defined at a specific time P2. The P2 is a specific time later than the peak value of an intake pipe internal pressure PB of a previous cycle. In the cycle, P3 is a specific time that is set immediately before the calculation of the injection time. A second throttle opening TH2 is defined at P3. The fuel injection controller corrects a fuel injection amount based on variation in correction time ta0 at the first throttle opening TH0 to correction time ta1 at the second throttle opening TH1. The time P2 is later than time P1, which is the peak value of the intake pipe internal pressure of the previous cycle. Accordingly, the fuel injection amount correction is completely unaffected or only slightly affected by the intake pipe internal pressure, thus ensuring close-to-ideal correction.

A vehicle control system includes a processor programmed to control a vehicle subsystem according to a recovered signal generated from an output signal of a sensor, and a product of a time constant of the sensor and filtered changes of the output signal with respect to time such that a magnitude and phase of the recovered signal approach a magnitude and phase of an input signal to the sensor.

A control system comprising a variable valve timing mechanism (B) able to set a closing timing of an intake valve (7), a fuel injector (13) for feeding fuel to a combustion chamber (5), an intake air amount detector (17) for detecting an amount of intake air fed to an intake passage from the outside air, and a pressure sensor (16) for detecting the pressure in the intake passage downstream of a throttle valve (16). When air in the combustion chamber (5) is blown back to the intake passage when injection of fuel is restarted after the fuel injection is stopped at the time of deceleration operation, the basis for calculation of the fuel injection amount in the initial cycle when fuel injection is restarted is switched from the amount of intake air detected by the intake air amount detector (17) to the pressure in the intake passage detected by the pressure sensor (18).

A fuel injection amount control apparatus comprises an air-fuel ratio sensor disposed between an exhaust gas merging portion and an upstream catalyst. The control apparatus performs a feedback correction on an amount of fuel to be injected by the fuel injection valve so that an air-fuel ratio represented by the output value of the upstream air-fuel ratio sensor becomes equal to a target air-fuel ratio set at stoichiometric air-fuel ratio. The control apparatus obtains an air-fuel ratio imbalance indicating value, which becomes larger as a difference in air-fuel ratio of each of the mixtures supplied to each of the combustion chambers among the cylinders becomes larger, and performs an increasing correction to the instructed fuel injection amount in such a manner that an air-fuel ratio determined by the instructed fuel injection amount becomes richer than the stoichiometric air-fuel ratio as the obtained air-fuel ratio imbalance indicating value increases.

An exhaust purification system includes: an NOx reduction type catalyst, which is provided in an exhaust system; and a regeneration treatment unit, which recovers an NOx purification capacity of the NOx reduction type catalyst, wherein the regeneration treatment unit includes: a target setting unit, which sets a target injection amount of at least one of a post injection and an exhaust pipe injection that is required for setting an excess-air-ratio of the exhaust gas to the target excess-air-ratio, based on a suction air amount of the internal combustion engine, the target excess-air-ratio, and a fuel injection amount of the internal combustion engine; and an injection controller, which controls an injection amount of at least one of the post injection and the exhaust pipe injection, based on the target injection amount input from the target setting unit.

Systems, methods and apparatus for controlling operation of an engine structured to combust gaseous fuel such as a dual fuel engine, including an estimation of key parameters dependent on natural gas quality, are disclosed. The natural gas quality parameters are estimated from natural gas properties obtained from various sensed parameters associated with the engine.

A fuel injection control device of an engine is disclosed, that is provided with a fuel injection valve configured to inject a fuel according to a target pulse width into an intake passage, an intake flow rate detection unit arranged to detect a flow rate of an intake air supplied to the engine, an intake pressure detection unit arranged to detect an intake pressure in the intake passage, a fuel pressure detection unit arranged to detect a pressure of a fuel supplied to the fuel injection valve, and a pressure control unit configured to control the fuel pressure according to an engine operation state. The device is further provided with a request pulse width calculation unit configured to calculate a request pulse width on the basis of an intake flow rate detected by the intake flow rate detection unit, a fuel pressure detected by the fuel pressure detection unit, and a differential pressure between the fuel pressure and an intake pressure detected by the intake pressure detection unit, a post-correction request pulse width calculation unit configured to calculate a post-correction request pulse width through correcting the request pulse width according to the differential pressure, when injecting a fuel of which flow rate is lower than a predetermined flow rate; and a target pulse width setting unit configured to set the target pulse width on the basis of the post-correction request pulse width.

On start of an engine, a difference ΔPm between a first intake pipe pressure Pm1 and a second intake pipe pressure Pm2 is computed. Reduction correction of wall surface deposition correction is prohibited until the state that the difference ΔPm is equal to or less than a reference value ΔPmref continues over a predetermined number of strokes nref of the engine. After the state that the difference ΔPm is equal to or less than the reference value ΔPmref continues over the predetermined number of strokes nref of the engine, permission is given for the reduction correction.