Deteriorated condition detecting apparatus for an oxygen sensor
US4121548A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 8, 1977 |
| Grant date | Oct 24, 1978 |
| Priority date | — |
| Expiry date | Jul 8, 1997 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF01N2550/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A deteriorated condition detecting apparatus for an oxygen concentration sensor used in an air-fuel ratio feedback control for an internal combustion engine comprises a reference oxygen concentration sensor mounted in proximity to the oxygen concentration sensor used for the air-fuel ratio feedback control and a discriminator for comparing duty factors of output signals from those two sensors to determine a deteriorated condition of the oxygen sensor. The discriminator determines the deteriorated condition when the duty factor of the sensor under test deviates from the duty factor of the output signal of the reference sensor by a predetermined amount. It converts the outputs of the respective sensors to square wave signals and integrates one of the levels of the square wave signals to determine the duty factors, and differentially amplifies the integrated signal to produce a differential output signal, which is then compared with a predetermined level to determine whether there exists a deviation of the duty factor corresponding to the deteriorated condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.