A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method determines an estimate of an exhaust gas oxygen sensor time constant according to a comparison of air/fuel ratios and a system time constant.

A control device (40) is connected to a differential pressure sensor (41), a navigation system (42), and a fuel injection valve (17). The control device (40) is configured to: execute a regeneration control of monitoring a purification situation (C1) and supplying unburned fuel (F2), which is injected from the fuel injection valve (17) and does not contribute to driving, to an exhaust gas purification system (20) in a case where the purification situation (C1) becomes a deteriorated situation (Ca); and execute a control of monitoring a road situation (C2) and stopping the regeneration control before the road situation (C2) actually becomes an accelerator off situation (Cb) in which an accelerator opening degree (1) of an accelerator pedal (43) becomes off.

An exhaust gas recirculation apparatus including an engine; a suction line; an exhaust line; a post-processing unit which is disposed in the exhaust line to reduce hazardous substances contained in the exhaust gas; a first circulation line which guides a part of the exhaust gas, which is guided to the exhaust line, to the suction line; a second circulation line which guides a part of the exhaust gas, which is guided to a downstream side of the post-processing unit, to the suction line; and a bypass line which branches off from an upstream side of the second circulation line, and merges with a downstream side of the second circulation line, wherein ammonia slip, which is discharged from the post-processing unit, is prevented from being guided to the suction line.

A controller is applied to such an internal combustion engine that an exhaust throttle valve for controlling the flow volume of exhaust gas of the exhaust passage is provided in the exhaust passage, an intake variable valve mechanism for changing the timing of opening and closing each intake valve or an exhaust variable valve mechanism for changing the timing of opening and closing each exhaust valve is provided, and an overlap period when an opening period of the intake valve and an opening period of the exhaust valve overlap with each other can be provided, and controls the exhaust throttle valve so that an opening degree of the exhaust throttle valve in the overlap period is made smaller than an opening degree of the exhaust throttle valve in a case where the overlap period is not provided.

An internal combustion engine includes an intercooler configured to cool an intake gas compressed by a compressor, a cooler bypass passage configured to bypass the intercooler, and a cooler bypass valve configured to open and close the cooler bypass passage, and an exhaust gas recirculation gas is introduced into an upstream side of the intercooler. An electronic control unit is configured to open the cooler bypass valve during use of a high exhaust gas recirculation rate region, and to close the cooler bypass valve during use of a low exhaust gas recirculation rate region.

Methods and systems are provided for improving boost pressure control by adjusting a variable compressor recirculation valve. In one example, a method may include adjusting a position of a continuously variable compressor recirculation valve based on amount of sludge accumulation on the valve. The amount of sludge accumulation may be estimated based on a difference between total intake flow downstream of a compressor recirculation passage outlet but upstream of the passage, and total engine flow entering engine cylinders.

The purpose of the present invention is to provide an engine with reforming cylinders which are fuel reforming devices capable of supplying a reformed fuel according to the outputs of outputting cylinders. The engine is provided with the outputting cylinders for burning the fuel and the reforming cylinders which are the fuel reforming devices for reforming the fuel through the reciprocating motions of pistons. The amount of reformed fuel supplied to all the outputting cylinders is changed according to the outputs of the outputting cylinders while maintaining the amount of supplied fuel and the amount of suctioned gas, which are supplied into one reforming cylinder.

An ignition device for an internal combustion engine (1) includes a superpose voltage generation circuit (47) that, after the initiation of a discharge with the application of a discharge voltage by a secondary coil, applies a superpose voltage between electrodes of an ignition plug (29) in the same direction as the discharge voltage to continue a discharge current, and performs a superposed discharge in a superposed discharge activation range of high exhaust recirculation rate. Upon shift from the superposed discharge activation range of high exhaust recirculation rate to a superposed discharge deactivation range of low exhaust recirculation rate, the deactivation of the superposed discharge is delayed by a delay time T. Although the exhaust gas recirculation rate becomes temporarily increased with decrease in intake air after the closing of an exhaust gas recirculation control valve, the superposed discharge is continued for the delay time T so as to avoid misfiring.

An engine control system for a vehicle includes a flowrate module, first and second mass fraction calculating modules, and an actuator control module. The flowrate module determines a mass flowrate of exhaust gas recirculation (EGR) to an engine. The first mass fraction calculating module, based on the mass flowrate of EGR, determines a first mass fraction of recirculated exhaust gas relative of a first gas charge for a first combustion event of the engine. The second mass fraction calculating module determines a second mass fraction of recirculated exhaust gas of a second gas charge for a second combustion event of the engine based on an average of the first mass fraction and one or more other values of the first mass fraction determined for other combustion events, respectively. The actuator control module selectively adjusts an engine operating parameter based on the second mass fraction.

In response to decrease of a requested torque to a reference value or smaller, a value of a virtual air-fuel ratio that is used in calculation of a target air amount for achieving the requested torque is changed from a first air-fuel ratio to a second air-fuel ratio that is leaner than the first air-fuel ratio. The target air amount is calculated backwards from the requested torque by using the virtual air-fuel ratio. After the value of the virtual air-fuel ratio is changed from the first air-fuel ratio to the second air-fuel ratio, the target air-fuel ratio is switched from the first air-fuel ratio to the second air-fuel ratio. A target EGR rate is calculated by using the virtual air-fuel ratio. The target EGR rate is preferably determined by minimum value selection between a first target value of an EGR rate that is calculated by using the virtual air-fuel ratio, and a second target value of the EGR rate that is calculated by using the target air-fuel ratio.