Method and apparatus for flow measurement with temperature and density compensation
US6390999B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 1997 |
| Grant date | May 21, 2002 |
| Priority date | — |
| Expiry date | Jun 26, 2017 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61M2205/3375
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A transit time ultrasonic flow meter includes a pair of ultrasonic transducers transmitting an ultrasonic signal through a fluid flowing in a conduit and receiving the transmitted ultrasonic signal. An exclusive-OR (XOR) phase comparator then detects a difference in phase between the received ultrasonic signal and a reference signal having a selected phase shift (e.g., 0°, 90°, 180°, or 270°) with respect to the transmitted ultrasonic signal. Control circuitry selects the phase shift of the reference signal based on outputs of the XOR phase comparator in order to maintain the phase shifts detected by the XOR phase comparator within a range in which the comparator has relatively accurate detection (e.g., 45° to 135°). By adjusting the phase of the reference signal and thereby maintaining the XOR phase comparator in its relatively high accuracy region, the present invention enhances the accuracy of detection by the phase comparator. Since the outputs of the phase comparator are correlated to fluid flow, adjusting the phase of the reference signal also enhances the inventive flow meter's measurement of fluid flow. The present invention also provides what is com…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.