Exhaust purification control device and exhaust purification system

Abstract

An exhaust purification control device is provided for an exhaust purification system that includes an exhaust treatment device located in an outlet passage of an internal combustion engine and a fuel addition valve. The control device includes an actual air-fuel (A/F) ratio detecting means for detecting an actual A/F ratio based on an output signal of an A/F ratio sensor, an estimated A/F ratio calculating means for calculating an estimated A/F ratio, an addition valve controlling means for instructing the fuel addition valve to add fuel into the outlet passage, and an addition valve abnormality determining means for determining whether the fuel addition valve is abnormal based on the actual A/F ratio and the estimated A/F ratio. The exhaust purification control device can thereby determine normal and abnormal operation of the fuel addition valve.

1 . An exhaust purification control device capable of placement in an exhaust purification system that includes an exhaust treatment device located in an outlet passage of an internal combustion engine and a fuel addition valve, the exhaust purification control device comprising:
 an actual air-fuel (A/F) ratio detecting means for detecting an actual A/F ratio based on an output signal from an A/F ratio sensor located downstream of the fuel addition valve;   an estimated A/F ratio calculating means for calculating an estimated A/F ratio based on a fuel injection amount of fuel injected into the internal combustion engine from a fuel injection valve, a fuel addition amount of the fuel to be added into the outlet passage from the fuel addition valve, and an inlet air amount supplied into the internal combustion engine;   an addition valve controlling means for instructing the fuel addition valve to add the fuel addition amount into the outlet passage; and   an addition valve abnormality determining means for determining whether the fuel addition valve is abnormal based on the actual A/F ratio and the estimated A/F ratio.   
   
   
       2 . The exhaust purification control device according to  claim 1 , wherein
 the addition valve abnormality determining means determines whether the fuel addition valve is abnormal based on the actual A/F ratio and the estimated A/F ratio in a non-driven state in which the addition valve controlling means does not instruct the fuel addition valve to add the fuel addition amount.   
   
   
       3 . The exhaust purification control device according to  claim 1 , wherein
 the addition valve abnormality determining means determines whether the fuel addition valve is abnormal based on the actual A/F ratio and the estimated A/F ratio in a driven state in which the addition valve controlling means instructs the fuel addition valve to add the fuel addition amount.   
   
   
       4 . The exhaust purification control device according to  claim 1 , further comprising:
 an A/F ratio sensor abnormality determining means for determining whether the A/F ratio sensor is abnormal, wherein   the addition valve abnormality determining means stops an abnormality determination with respect to the fuel addition valve when the A/F ratio sensor is determined to be abnormal.   
   
   
       5 . The exhaust purification control device according to  claim 1 , wherein
 the exhaust treatment device includes a NO x  catalyst configured to reduce NO x  removed from the exhaust by the fuel addition amount added from the fuel addition valve.   
   
   
       6 . The exhaust purification control device according to  claim 5 , wherein
 the exhaust treatment device further includes a filter configured to remove a particulate from the exhaust.   
   
   
       7 . The exhaust purification control device according to  claim 6 , wherein
 the particulate removed by the filter is burned by a second fuel injection amount of the fuel from of a post injection performed by the fuel injection valve, and   the addition valve abnormality determining means stops an abnormality determination with respect to the fuel addition valve in the post injection.   
   
   
       8 . The exhaust purification control device according to  claim 6 , wherein
 the particulate removed from the exhaust is burned by the fuel addition amount added from the fuel addition valve so that the filter is regenerated.   
   
   
       9 . An exhaust purification system comprising:
 an exhaust treatment device provided in an outlet passage of an internal combustion engine and configured to remove a component in an exhaust discharged from the internal combustion engine;   a fuel addition valve configured to purify the harmful component removed by the exhaust treatment device by adding an fuel addition amount of fuel into the outlet passage;   an A/F ratio sensor located downstream of the fuel addition valve; and   the exhaust purification control device including:   an actual air-fuel (A/F) ratio detecting means for detecting an actual A/F ratio based on an output signal from an A/F ratio sensor located downstream of the fuel addition valve;   an estimated A/F ratio calculating means for calculating an estimated A/F ratio based on a fuel injection amount of the fuel injected into the internal combustion engine from a fuel injection valve, the fuel addition amount of fuel to be added into the outlet passage from the fuel addition valve, and an inlet air amount supplied into the internal combustion engine;   an addition valve controlling means for instructing the fuel addition valve to add the fuel addition amount of the fuel into the outlet passage; and   an addition valve abnormality determining means for determining whether the fuel addition valve is abnormal based on the actual A/F ratio and the estimated A/F ratio.