Thermal type gas flow measuring instrument
US7213455B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Dec 16, 2004 |
| Grant date | May 8, 2007 |
| Priority date | — |
| Expiry date | Dec 16, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/6965
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A thermal type gas flow measuring instrument measures gas flow with high precision by accurately correcting changes in radiation heat characteristics of a heating resistor due to contamination. The instrument comprises a second heating resistor 30 whose resistance value, which changes if contaminated, is calculated by measuring the terminal voltage thereof by calculating means 32, and the calculated value is compared with a temperature detected by a temperature detecting element 31. Based on the result of comparison, the level of contamination of the second heating resistor 30 is determined. The second heating resistor 30 and the first heating resistor 3 are disposed in similar environments such that their levels of contamination can be considered equal. Based on the level of contamination calculated from the result of comparison, a correction value is calculated and the output of the first heating resistor 3 is corrected in accordance with the correction value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.