EXHAUST GAS PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust gas purification device has: a catalyst to purify exhaust gas by reduction of nitrogen oxide included in the exhaust gas discharged from a combustion chamber of the engine, which catalyst has a purification efficiency of the nitrogen oxide varying depending on a temperature of the catalyst; a supply means capable of supplying a reduction agent for the reduction of the nitrogen oxide to the exhaust gas guided to the catalyst; and a control means having a configuration capable of controlling the temperature of the catalyst depending on an operating condition of the engine. The device has a configuration to prohibit controlling the temperature of the catalyst when a condition of being incapable of supplying the reduction agent in an amount corresponding to the temperature of the catalyst is satisfied, even if the temperature of the catalyst needs to be controlled.