Gas flow measuring system
US4271701A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 15, 1978 |
| Grant date | Jun 9, 1981 |
| Priority date | — |
| Expiry date | Mar 15, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The pressure difference across a pneumotach restriction is sampled with a gas chopper connected across a pressure difference detecting transducer. The gas chopper alternates the pressures backward and forward in application to the transducer so that the latter develops an AC sampling signal, the strength of which is related to flow. This AC signal is sampled in synchronism over intervals having a duration related to the power line frequency to develop an integrated value of the pressure difference free of drift caused by power line interference. The resultant signal is smoothed and summed in alternating response at double the gas chopper sampling rate to give a smooth output which is then multiplied by a linearizing circuit to obtain a flow signal which is proportional to the pressure difference. Specific gas flow structures and electronic sampling circuitry are disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.