US Patent 11168597 Exhaust gas purification system for a hybrid vehicle

In a hybrid vehicle, suppression of an amount of fuel consumed for reducing NOx stored in an NSR catalyst and suppression of deterioration in exhaust gas components due to unreacted fuel flowing out from the NSR catalyst are made compatible with each other. Predetermined power source control is carried out in accompany with the execution of NOx reduction processing to supply fuel to the NSR catalyst. In the predetermined power source control, an engine rotation speed of an internal combustion engine is made to decrease or an operation of the internal combustion engine is made to stop, and an electric motor is controlled so as to compensate for required torque. Further, during a period of execution of the predetermined power source control, a lower limit value of a predetermined target SOC range for an SOC of a battery is changed to a value smaller than at times other than the period of execution of the predetermined power source control.