System for detection of air/fuel ratio in IC engine by using oxygen sensor operated with supply of current
US4440621A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 2, 1982 |
| Grant date | Apr 3, 1984 |
| Priority date | — |
| Expiry date | Dec 2, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/4065
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An air/fuel ratio detection system for an IC engine, using an oxygen sensor element of the concentration cell type which has a laminate of a measurement electrode layer exposed to the exhaust gas, a porous layer of oxygen ion conductive solid electrolyte and a reference electrode layer and requires the supply of a small DC current thereto to produce a reference oxygen partial pressure at the reference electrode by a balance between migration of oxygen ions to the reference electrode and diffusion of oxygen molecules therefrom. To prevent excessive rise in the reference oxygen partial pressure even when the engine continues to discharge exhaust gas high in the content of oxygen, the detection system has a control circuit which controls the intensity and flow direction of the current for the sensor element with reference to a voltage which is produced by adding a definite voltage to, or subtracting the definite voltage from, the sensor output voltage depending on the level of oxygen content in the exhaust gas indicated by the sensor output voltage and smoothing the voltage resulting from the addition or subtraction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.