A controller for an internal combustion engine is configured to execute a dither control process, a purge control process, and a limiting process. The dither control process operates the fuel injection valves such that at least one of the cylinders is a lean combustion cylinder, in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and at least another one of the cylinders is a rich combustion cylinder, in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio. The purge control process controls the purge flow rate by operating the adjustment device. The limiting process limits the purge control process such that, when the dither control process is being executed, the purge flow rate is reduced as compared to a case in which the dither control process is not being executed.

A control device for an internal combustion engine includes an electronic control unit configured to perform dither control processing for controlling the fuel injection valve based on a requested injection amount such that a part of cylinders among a plurality of cylinders becomes a lean combustion cylinder and cylinders different from the part of cylinders among the cylinders become a rich combustion cylinder, and restriction processing for, in a case where the requested injection amount is equal to or greater than a first injection amount, making no restriction on the dither control processing, and in a case where the requested injection amount is within a second injection amount range of an injection amount smaller than the first injection amount, restricting the dither control processing to a side where a leaning degree of an air-fuel ratio of a cylinder having a leanest air-fuel ratio among the cylinders decreases.

Technical solutions are described for an emissions control system for a motor vehicle including an internal combustion engine. An example emissions control system for treating exhaust gas in a motor vehicle including an internal combustion engine. For example, the emissions control system includes a selective catalytic reduction (SCR) device, an NOx sensor, and a controller that is configured to detect a NH3 slip of the SCR device. The controller detects the NH3 slip by modulating an engine out NOx from an engine, demodulating the engine out NOx from the engine to original state, and measuring NOx upstream and downstream from the SCR device after the modulation. Further, the controller determines the NH3 slip by comparing gradients in the NOx measurement with one or more predetermined thresholds.

A control apparatus for an internal combustion engine is provided. The control apparatus is equipped with an electronic control unit. A CPU with which this electronic control unit is equipped performs dither control for setting a first cylinder as a rich-burn cylinder whose air-fuel ratio is richer than a theoretical air-fuel ratio and setting each of second to fourth cylinders as a lean-burn cylinder whose air-fuel ratio is leaner than the theoretical air-fuel ratio, when a request to raise the temperature of a three-way catalyst is made. Then, the CPU reduces the degree of richness of the rich-burn cylinder and the degree of leanness of each of the lean-burn cylinders while continuing dither control, on the condition that fluctuations at a level equal to or higher than a predetermined value are caused in time-series data on the rotational speed resulting from the combustion in each of the cylinders.

When the air fuel ratio dither control is carried out, an air fuel ratio of a mixture in each of one or more lean cylinders and one or more rich cylinders is controlled so that an average value of an air fuel ratio of exhaust gas flowing into the three-way catalyst becomes a predetermined target exhaust gas air fuel ratio. At this time, the air fuel ratio dither control is carried out by setting, as the one or more rich cylinders, at least a cylinder for which a degree of uniformity of the flow speed distribution of exhaust gas, which is a degree of uniformity of the flow speed distribution of exhaust gas discharged from that cylinder on a cross section of the three-way catalyst, is the lowest in the cylinder group of an internal combustion engine.

Methods and systems are provided for a single heat exchanger coupled to a main exhaust passage upstream of one or more exhaust catalysts or in between two exhaust catalysts for exhaust heat recovery and exhaust gas recirculation (EGR) cooling. In one example, in the pre-catalyst configuration of the heat exchanger, during exhaust heat recovery, a portion of exhaust may be routed via the heat exchanger while the remaining portion of exhaust may be routed directly to the exhaust catalysts, and fueling may be adjusted on a per-cylinder basis to maintain a target exhaust air-fuel-ratio at the exhaust catalysts.

Methods and systems are provided for a single heat exchanger coupled to a main exhaust passage upstream of one or more exhaust catalysts or in between two exhaust catalysts for exhaust heat recovery and exhaust gas recirculation (EGR) cooling. In one example, in the pre-catalyst configuration of the heat exchanger, during exhaust heat recovery, a portion of exhaust may be routed via the heat exchanger while the remaining portion of exhaust may be routed directly to the exhaust catalysts, and fueling may be adjusted on a per-cylinder basis to maintain a target exhaust air-fuel-ratio at the exhaust catalysts.

An engine comprising: a fuel injection device including a rack and an actuator, the rack being configured to regulate the amount of fuel injected to a combustion chamber, the actuator being configured to control the position of the rack; and a control device that controls fuel injection performed by the fuel injection device based on an instructed revolution number, and that performs a dither control on the actuator, wherein the control device has information of a revolution number variation region that is based on the relationship between a dither frequency in the dither control and an engine revolution number, and upon determining that the instructed revolution number is within the revolution number variation region, changes at least one of the dither frequency and the instructed revolution number. Thus, an engine capable of reducing a periodic variation in engine speed which may be caused by a dither control is provided.

A control apparatus for an internal combustion engine includes an exhaust gas concentration parameter sensor, a cylinder gas amount parameter acquisition device, an air-fuel ratio controller, an operation status determination device, and a determination value setting device. The air-fuel ratio controller is to perform an air-fuel ratio fluctuation control to control an air-fuel ratio in the internal combustion engine to fluctuate in a predetermined state. The operation status determination device is to determine an operation status of the internal combustion engine or an auxiliary device of the internal combustion engine based on an exhaust gas concentration parameter detected by the exhaust gas concentration parameter sensor in a case where an amount of a cylinder gas represented by a cylinder gas amount parameter acquired by the cylinder gas amount parameter acquisition device is equal to or larger than a predetermined determination value while the air-fuel ratio fluctuation control is being performed.

In the dither current power supply control method, in order to prevent occurrence of a difference between the target average current and the detected average current, which is caused when a medium current (I0) between a dither large current (I2) and a dither small current (I1) and a waveform average (Ia) of the dither current are different from each other depending on a response time difference (ab) between a rise time (b) and a fall time (a) of the dither current, negative feedback control is carried out by using a command medium current corresponding to the target average current corrected by a correction parameter based on experimentally measured data, thereby suppressing occurrence of a transient fluctuation error by the negative feedback control, so that a highly precise and stable load current is acquired.