Method for measuring NOx concentration and NOx concentration sensor
US6344134B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 1999 |
| Grant date | Feb 5, 2002 |
| Priority date | — |
| Expiry date | Jan 15, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/417
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus and method using a two-serial space sensor (having first and second internal spaces 2,3) for accurately measuring NOx concentration in gas, e.g., exhausted from an internal combustion engine. Both NOx (nitrogen oxide) and oxygen are forced to be partially dissociated in the first space 2 to an oxygen concentration level of 2×10−7 to 2×10−10 atm by pumping out oxygen from the first space 2. The NOx concentration is determined based on the second current measured in the second space 4 and based on the NO dissociation percentage in the first chamber which is 0.5-50%, or preferably 2-20%. The NOx measurement accuracy is further improved when the above oxygen concentration level is maintained from 2×10−8 to 2×10−9 and the temperature drift of the sensor is maintained within ±5° C. under a sensor temperature range of 700-900° C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.