Closed loop bias air/fuel ratio offset to enhance catalytic converter efficiency
US5974785A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 1997 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Jan 16, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/12
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A method and system for reducing time required for a catalyst to reach optimum operating temperature control an air/fuel ratio based on the catalyst temperature to supply excess air to the catalyst during closed loop lambda control. A lambda bias or offset is varied as a function of the catalyst temperature, engine speed, and engine load to bias the air/fuel ratio lean of the stoichiometric ratio. Excess air may be supplied to the catalyst for a predetermined period after a cold engine start or at any time that the catalyst temperature is below its optimum operating temperature for efficient conversion. The bias or offset is reduced to zero after the catalyst reaches a desired operating temperature or the predetermined time period expires.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.