Device for determining deterioration of a catalyst for an engine
US5983629A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 7, 1997 |
| Grant date | Nov 16, 1999 |
| Priority date | — |
| Expiry date | Aug 7, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A device for determining deterioration of a catalyst having an O.sub.2 storage capability and disposed in an exhaust passage of an engine comprises: upstream and downstream air-fuel ratio sensors disposed in the exhaust passage upstream and downstream of the catalyst respectively for detecting air-fuel ratios of exhaust gas upstream and downstream of the catalyst. The air-fuel ratio of the exhaust gas flowing into the catalyst is controlled on the basis of the output of the upstream air-fuel ratio sensor to make the air-fuel ratio flowing into the catalyst a target air-fuel ratio. A ratio of the length of the response curve of the output of the downstream air-fuel ratio sensor to the length of the response curve of the output of the upstream air-fuel ratio sensor is calculated. A ratio of the frequency of the output of the downstream air-fuel ratio sensor to the frequency of the output of the upstream air-fuel ratio sensor is calculated. It is determined that the catalyst has deteriorated when the length ratio is greater than a first predetermined ratio, or when the length ratio is greater than a second predetermined ratio which is smaller than the first predetermined ratio and the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.