Oxygen concentration sensing apparatus
US4818362A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 1987 |
| Grant date | Apr 4, 1989 |
| Priority date | — |
| Expiry date | Mar 19, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/4065
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for sensing the concentration of oxygen in a gas such as engine exhaust gas includes an oxygen concentration sensor formed of an oxygen pump element and a sensor cell element, each based on a solid electrolytic member formed of a material such as ZrO.sub.2, and is provided with a limiter circuit which functions to reduce the level of current supplied to the oxygen pump element when a voltage produced by the sensor cell element indicates that this current level is such as to produce a "blackening" phenomenon whereby deterioration of the oxygen pump element will occur and oxygen concentration sensing reliability will be lowered. The apparatus also includes a delay circuit which functions such that a reduction of the oxygen pump element current level is delayed by a predetermined time interval, after an increase of the sensor cell element voltage to the "blanking" region is detected, thereby preventing fluctuations in the oxygen pump element current level due to transient increases in sensor cell element voltage and increasing the sensing reliability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.