Exhaust emission control device of internal combustion engine
US6233923A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 21, 2000 |
| Grant date | May 22, 2001 |
| Priority date | — |
| Expiry date | Mar 21, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A primary deterioration diagnosis of a front catalyst (8) is performed based on the air-fuel ratio of the exhaust gas downstream of the front catalyst (8) detected in a first period each time the first period elapses when the engine (1) is running in a diagnosis region. A secondary deterioration diagnosis of the front catalyst (8) is performed based on the air-fuel ratio of the exhaust gas downstream of the front catalyst (8) detected in a second period longer than the first period each time the second period elapses when the engine (1) is running in the diagnosis region. When SOx discharge control is performed, primary diagnosis and secondary diagnosis are prohibited, and if it is determined in the primary diagnosis that the front catalyst (8) has deteriorated, SOx discharge control is prohibited to provide an opportunity for secondary diagnosis. In this way, the deterioration diagnosis of the front catalyst (8) can be precisely performed even if there are few opportunities for diagnosis due to lean air-fuel ratio running or SOx discharge control.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.