Exhaust gas purification system for an internal combustion engine
US5201802A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 1992 |
| Grant date | Apr 13, 1993 |
| Priority date | — |
| Expiry date | Jan 31, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
An exhaust gas purification system for an internal combustion engine includes an engine capable of fuel combustion at lean air-fuel ratios, a catalyst constructed of zeolite carrying at least one metal selected from the transition metals and noble metals to reduce NOx under oxidizing gas conditions and in the presence of HC. The exhaust gas purification system also includes a device for determining degradation of the catalyst, and a device for increasing the amount of HC or changing a catalyst temperature to a higher side when it is determined that the catalyst has been degraded. The NOx purification rate of the catalyst is maintained high even after the catalyst has been degraded.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.