Engine exhaust purifier
US5771690A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 1997 |
| Grant date | Jun 30, 1998 |
| Priority date | — |
| Expiry date | Jan 16, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A50/20
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
Two catalytic converters are disposed in series midway in an engine exhaust passage, and a by-pass valve selectively introduces exhaust into the upstream converter and a by-pass passage which by-passes the converter. When the catalyst temperature of the upstream catalytic converter exceeds a threshold value A, exhaust is routed to the by-pass passage. The catalyst temperature in the state when exhaust is routed to the upstream catalytic converter under steady state engine running conditions is stored as a convergence temperature depending on the engine running conditions. When exhaust is routed to the by-pass passage, exhaust is re-introduced into the upstream converter only when both the catalyst temperature and the convergence temperature corresponding to the running conditions at that time are less than a threshold value B which is less than the threshold value A. In this way, hunting of the by-pass valve operation is prevented.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.