Catalyst deterioration diagnosis system for internal combustion engine
US5640847A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 18, 1995 |
| Grant date | Jun 24, 1997 |
| Priority date | — |
| Expiry date | Oct 18, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A catalyst deterioration diagnosis system for an internal combustion engine having an exhaust gas passageway in which a catalytic converter having a catalyst is disposed. The diagnosis system comprises a first air-fuel ratio sensor disposed in the exhaust gas passageway upstream of the catalytic converter, and a second air-fuel ratio sensor disposed in the exhaust gas passageway downstream of the catalytic converter. The diagnosis system further comprises a control unit connected to the air-fuel ratio sensors and arranged to make an air-fuel ratio feedback control mainly in response to an output signal of the first air-fuel ratio sensor. The control unit includes means for calculating an inversion ratio value relating to an inversion ratio of output signals from the first and second air-fuel ratio sensors when the engine operating condition is within a diagnosis region requiring a diagnosis of deterioration of the catalyst, means for detecting an inversion state value relating to a state of inversion of the output signal of the first air-fuel ratio sensor, means for setting a decision standard value in accordance with the inversion state value from the inversion state value detecti…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.