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.

This disclosure includes engines that are capable of controlling an air-fuel ratio responsive to rapid changes in the calorific value of a fuel gas. Some engines include an A/F valve, a solenoid valve, and a control unit configured to close the A/F valve when an average opening degree of the solenoid valve is lower than a preset target opening degree, and open the A/F valve when the average opening degree is equal to or higher than the target opening degree. In some engines, when the opening degree of the solenoid valve has been an upper limit opening degree or a lower limit opening degree of the solenoid valve over a predetermined number of times, the control unit is configured to compare with the upper or lower limit opening degree, in lieu of the average opening degree, against the target opening degree to open or close the A/F valve.

A controller for an internal combustion engine is configured to execute a dither control process and a filter temperature calculating process. In the dither control process, on condition that an execution request for a regeneration process of the filter is made, fuel injection valves are operated such that at least one of the cylinders is a lean combustion cylinder, and at least another one of the cylinders is a rich combustion cylinder. The filter temperature calculating process is a process of calculating the temperature of the filter to be lower when a target value of an average value of the exhaust air-fuel ratio in a predetermined period by the dither control is leaner than the stoichiometric air-fuel ratio than when the target value is the stoichiometric air-fuel ratio.

A controller executes a dither control process and a deposition amount calculating process. In the dither control process, on condition that an execution request for a regeneration process of the filter is made, fuel injection valves are operated such that at least one of the cylinders is a lean combustion cylinder, and at least another one of the cylinders is a rich combustion cylinder. In the deposition amount calculating process, a deposition amount is calculated such that, as compared to a case in which a target value of an average value of an exhaust air-fuel ratio in a predetermined period by the dither control process is a first air-fuel ratio, a decrease amount per unit time of the deposition amount is calculated to be a great value in a case in which the target value is a second air-fuel ratio, which is leaner than the first air-fuel ratio.

A hybrid vehicle includes an engine that has a particulate matter filter, a motor, and an electronic control unit. The electronic control unit is configured to control the engine and the motor such that an intermittent operation of the engine is permitted and the hybrid vehicle travels with required power when a vehicle speed is lower than a first predetermined vehicle speed. The electronic control unit is configured to inhibit the intermittent operation of the engine when a deposition amount of particulate matters is equal to or greater than a first deposition amount and a state in which the vehicle speed is equal to or higher than a second predetermined vehicle speed and is lower than the first predetermined vehicle speed is continued for a first predetermined time.

A first limit requesting process limits a dither control process of fuel injection valves in such a manner that the absolute value of the difference between the air-fuel ratios of the cylinders becomes smaller when the degree of variation of the injection amounts of the fuel injection valves provided for respective cylinders is great than when the degree of variation is small. A second limit requesting process limits the dither control process in such a manner that the absolute value is smaller when the torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small. The limiting process limits the dither control process in accordance with one of requests generated by the first limit requesting process and the second limit requesting process that causes the absolute value to be smaller than the other.

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.

A controller for an internal combustion engine includes processing circuitry. The processing circuitry performs a dither control process and a multi-injection process. Multiple injections in the multi-injection process includes a first injection and a second injection performed at a timing retarded from the first injection. The dither control process includes at least one of a process performed on a cylinder changed to a lean combustion cylinder so that a reduction amount of fuel injected through the first injection is greater than a reduction amount of fuel injected through the second injection and a process performed on a cylinder changed to a rich combustion cylinder so that an increase amount of fuel injected through the first injection is greater than an increase amount of fuel injected through the second injection.

A controller for an internal combustion engine includes processing circuitry. The processing circuitry performs a dither control process. The dither control process includes a first mode in which a cylinder serving as a rich combustion cylinder is sequentially changed and a second mode in which a specified cylinder is fixed as one of a rich combustion cylinder and a lean combustion cylinder. The processing circuitry selects the first mode or the second mode based on an operating point of the internal combustion engine.

A controller for an internal combustion engine includes processing circuitry. The processing circuitry is configured to execute a dither control process under a condition in which a request for executing a regeneration process of a filter is made. The processing circuitry is further configured to execute a fuel cutting process stopping fuel injection performed by fuel injection valves under a condition in which an accelerator operation amount is zero and a prohibition process prohibiting the fuel cutting process under a condition in which the dither control process is executed.