Method of controlling exhaust gas purification system, and exhaust gas purification system

Abstract

In an exhaust gas temperature raising control for recovering purification ability of an exhaust gas purification device of an internal combustion engine, the exhaust gas temperature is efficiently raised to a target level without producing white smoke. In recovery control of the exhaust gas purification device, when the temperature of the exhaust gas flowing into the exhaust gas purification device is lower than a predetermined judgment value, a first exhaust gas temperature raising control that does not include post injection but includes intake air restriction is performed, and when equal to or higher than the predetermined judgment value, a second exhaust gas temperature raising control that includes both the post injection and the intake air restriction is performed to set an intake air restriction amount in the first exhaust gas temperature raising control greater than an intake air restriction amount in the second exhaust gas temperature raising control.