Patent ID: 7150144
Filing Date: 2006-12-19
Classification: F01N,F02B,F02D,Y02T

Abstract:
1. A control apparatus of an engine wherein lean NOx catalyst having a function of storing the NOx discharaed from a combustion chamber in the lean operation mode, and desorbing and cleaning said stored NOx in the rich operation mode is provided in an exhaust path, said control apparatus comprising: a sensor for detecting the amount or concentration of the NOx downstream from said lean NOx catalyst; calculation means A for calculating the amount of NOx downstream from the lean NOx catalyst in the lean operation mode, based on the output from said sensor; calculation means B for calculating the amount of NOx stored in the lean NOx catalyst; means for calculating the NOx storage capacity of said lean NOx catalyst, based on the results of calculations by the calculation means A and B setting means for setting a reference value A relative to the amount of NOx downstream from the lean NOx catalyst in the lean operation mode; setting means for setting a reference value B relative to the stored amount of NOx; comparison means A for comparing between the amount of NOx downstream from the lean NOx catalyst as a result of calculation by the calculation means A, and said reference value A; comparison means B for comparing between the amount of NOx stored in the lean NOx catalyst as a result of calculation by the calculation means A, and said reference value B; and diagnostic means for evaluating that: the amount of NOx discharged from the combustion chamber has reduced when the result of calculation by the calculation means A is smaller than the reference value A in the comparison means A, and the result of calculation by calculation means B is smaller than the reference value B in the comparison means B; the amount of NOx discharged from the combustion chamber has increased when the result of calculation by calculation means A is greater than the reference value A in the comparison means A, and the result of calculation by calculation means B is greater than the reference value B in the comparison means B; and the NOx storage capacity of the lean NOx catalyst has reduced when the result of calculation by calculation means A is smaller than the reference value A in the comparison means A, and the result of calculation by calculation means B is greater than the reference value B in the comparison means B.