To provide a catalyst degradation determination device capable of detecting sulfur concentration in fuel.
According to output reversion of a catalyst-posterior sensor 18, active air-fuel ratio control of alternately switching air-fuel ratio on the upstream of a catalyst 11 to rich and lean is performed, the oxygen storage capacity of the catalyst 11 is measured according to the execution thereof, and degradation of the catalyst 11 is determined based on the measurement value. A storage-reduction NOx catalyst 21 having a relatively small capacity is disposed between the catalyst 11 and the sensor 18, and an NOx sensor 22 is disposed on the downstream of the NOx catalyst 21. The sulfur concentration in fuel is detected based on the output of the NOx sensor during lean control. Since the output behavior of the NOx sensor during lean control is varied according to the sulfur concentration in fuel, this characteristic can be used to detect the sulfur concentration in fuel.
COPYRIGHT: (C)2010,JPO&INPIT
Toru Kisho
岩▲崎▼ 靖志
Hiroshi Miyamoto
Kimura Koichi
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| JP2001074727A |
Kazuo Abe