一种用于内燃发动机的废气净化系统,包括:NOx 储存还原催化剂,其设置于所述内燃发动机的排气通道中;还原添加阀,其设置于所述排气通道中所述NOx 储存还原催化剂的上游侧并且向废气添加还原剂;燃料过量供给控制执行装置,当还原储存于所述NOx 储存还原催化剂中的氧化物时,所述燃料过量供给控制执行装置执行周期性地将流入所述NOx 储存还原催化剂的所述废气的空燃比降低至目标空燃比的燃料过量供给控制,当降低所述废气的空燃比时,所述燃料过量供给控制执行装置通过所述还原剂添加阀多次执行在所属内燃发动机的曲轴转角处于指定范围中时执行的还原添加剂,以及添加阀堵塞判断装置,其判定所述还原添加阀是否已发生堵塞,其中,当所述添加阀堵塞判断装置判定所述还原添加阀已发生堵塞时,增加在所述燃料过量供给控制执行装置执行所述燃料过量供给控制期间降低所述废气的空燃比的次数。
A waste gas purification system, which is used for an explosive motor, comprises that: a NOx storing and reducing catalyst is arranged in an exhaust passage of the explosive motor; a valve for adding reducing agent is arranged at the upstream side of the NOx storing and reducing catalyst in the exhaust passage and adds reducing agent to waste gas; an executive device for controlling fuel oversupply, which executes controlling fuel oversupply, periodically declines the air fuel ratio of the inflowing waste gas in the NOx storing and reducing catalyst to target air fuel ratio, when the oxide stored in the NOx storing and reducing catalyst is reduced, and while the air fuel ratio of the inflowing waste gas is declined, the executive device for controlling fuel oversupply, by the valve for adding reducing agent, repeatedly executes adding reducing agent, which is executed when the Crank Angle of the explosive motor is in specified ranges; and a blocking judge device of the valve for adding reducing agent judges that whether blocking occurs in the valve for adding reducing agent, wherein, when the blocking judge device judges that blocking occurs in the valve for adding reducing agent, the times of declining the air fuel ratio executed by the executive device for controlling fuel oversupply during the period of controlling fuel oversupply, is increased.
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