Brennkraftmaschine mit NOx-Katalysator für Magergemischverbrennung

摘要

An engine having in an exhaust system a lean NOx catalyst (39) for purifying nitrogen oxide in an oxygen excessive exhaust gas by using a reducing agent, includes an intake air quantity decreasing means (70) for decreasing a quantity of intake air flowing through an intake system when the nitrogen oxide needs to be purified by the lean NOx catalyst, and a combustion heater (17) provided separately from the internal combustion engine (1) also serves as a CO2 adding device for adding carbon dioxide to the intake air when a flowing quantity in the intake system decreases by operating the intake air quantity decreasing means. With this arrangement, the reducing agent such as hydrocarbon and the like can be supplied even when eliminating an auxiliary injection hitherto needed in the internal combustion engine having the lean NOx catalyst.