Exhaust gas purifying system of internal combustion engine
US6539709B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 20, 2001 |
| Grant date | Apr 1, 2003 |
| Priority date | — |
| Expiry date | Apr 20, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/12
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A first NOx-trapping catalyzer unit is disposed on an upstream part of an exhaust passage. A second NOx-trapping catalyzer unit is disposed on a downstream part of the exhaust passage. A structure is provided that causes the first NOx-trapping catalyzer unit to be exposed to a relatively high temperature environment and causes the second NOx-trapping catalyzer unit to be exposed to a relatively low temperature environment. Each of the first and second NOx-trapping catalyzer units traps NOx when the exhaust gas applied thereto shows a leaner air/fuel ratio and releases and reduces NOx when the exhaust gas applied thereto shows a stoichiometric or richer air/fuel ratio. The first NOx-trapping catalyzer unit shows the basicity that is higher than that of the second NOx-trapping catalyzer unit or the first NOx-trapping catalyzer shows the reducing ability that is lower than that of the second NOx-trapping catalyzer unit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.