| 摘要 |
<p>PURPOSE: To reactivate the purifying capacity of exhaust gas purifying catalyst, and control the discharge of nitrogen oxides to be low by providing an unburnt gas increasing means increasing the amount of unburnt gas exhausted to the exhaust gas purifying catalyst from an internal combustion engine. CONSTITUTION: An intake pipe 9 is connected to the intake port 2 of an internal combustion engine 1 through an intake manifold on which a fuel injection valve is mounted. An ECU 23 allows interruption to be executed by mis-firing control every time when a crank angle interlocking signal occurs, which is supplied by a crank angle sensor 18. Every time when the amount of catalyst exhaust NOx exceeds a specified threshold value, ignition for a specified cylinder is thinned at the specified period of mis-firing over a specified number of times, and unburnt gas is intermittently supplied to NOx catalyst 13a. By this constitution, NOx is sufficiently reduced from the NOx catalyst 13a so as to be removed, and the NOx absorption capacity of the NOx catalyst 13a is thereby well reactivated. Thus as mentioned above, the purifying capacity of exhaust gas purifying catalyst can be reactivated, and the discharge of nitrogen oxides can also be controlled to be low at all times.</p> |
