Catalytic converter efficiency monitoring
US5157919A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 22, 1991 |
| Grant date | Oct 27, 1992 |
| Priority date | — |
| Expiry date | Jul 22, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
An on-board catalytic converter efficiency monitoring system uses an exhaust gas oxygen sensor downstream of a converter to enable closed loop air-fuel ratio control. The period of the air-fuel limit cycle is used to determine a time constant parameter of the feedback loop. A parameter in the fuel controller is changed to induce another air-fuel limit cycle frequency. The period of this new air-fuel limit cycle provides additional information with respect to the time constant of the feedback loop. Because it is possible to make other changes to the parameters of the fuel controller, different frequencies can be induced and additional parameters of the feedback loop time constant can be determined. With n different frequencies produced by n different fuel controller parameters it is possible to solve for n different time constants. The system can be used with either one or two EGO sensors depending upon the desired parameter to be solved. It is particularly advantageous to use one EGO sensor downstream of a converter to determine the catalytic efficiency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.