Patent ID: 8555615

Claim:
An internal combustion engine exhaust gas control system, which is applied to a hybrid vehicle that is powered by an internal combustion engine and an electric motor, the internal combustion engine exhaust gas control system comprising: an exhaust gas control catalyst provided in an exhaust passage of the internal combustion engine; an exhaust throttle valve, provided downstream of the exhaust gas control catalyst, that changes a sectional area of the exhaust passage; an electronic control unit; a memory, the memory storing instructions that when executed cause the electronic control unit to perform as: a first catalyst warm-up device that warms up the exhaust gas control catalyst by increasing a fuel injection quantity in the internal combustion engine; an assist amount adjusting device that adjusts assist torque generated by the electric motor such that the sum of engine torque, after the fuel injection quantity has been increased, and the assist torque is substantially equal to a required torque; and a second catalyst warm-up device that warms up the exhaust gas control catalyst by decreasing an opening amount of the exhaust throttle valve, wherein: the first catalyst warm-up device increases the fuel injection quantity to increase a temperature of exhaust gas flowing into the exhaust gas control catalyst to a target exhaust gas temperature when the opening amount of the exhaust throttle valve is reduced to a target opening amount, the target exhaust gas temperature is calculated by adding a reference temperature difference to a detected exhaust gas control catalyst temperature, and an increase amount of the fuel injection quantity is reduced as the target opening amount of the exhaust throttle valve is reduced.