Patent ID: 9724643
Date: 2017-08-08
CPC Classifications: B01D,F01N,F02D,Y02T

Claim:
1. An exhaust gas purification system for an engine that includes a diesel particulate filter (DPF) for collecting particulate matter (PM) in an exhaust gas exhausted from the engine to an exhaust passage, the exhaust gas purification system comprising: a central processing unit (CPU) and a memory storing instructions that causes the CPU to: classify a PM accumulation state of the DPF into multiple evaluation stages based on a plurality of evaluation indices, said PM accumulation state classifying step includes: determining a current evaluation stage; and determining whether to move up the current evaluation stage to an evaluation stage of a next rank when a value of each of a prescribed number of the evaluation indices is greater than each threshold value; repeatedly performing determination of the current evaluation stage and determination of whether to move up the current evaluation stage to the evaluation stage of the next rank; and said instructions further cause the CPU to: detect a defect of different types of sensors used for calculating each of the plurality of evaluation indices; and redetermine the current evaluation stage without using, among the different types of sensors, a sensor of which a defect is detected by the defect detection step; and newly redetermine the current evaluation stage as a substitute for the current evaluation stage upon detection of a defect of the sensor, by using an evaluation index other than an evaluation index based on an output value of the sensor of which a defect is detected, wherein a regeneration treatment of the PDF is executed based on the newly determined current evaluation stage when the defect of the sensor is detected.