Respiration flowmeter
US4425805A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1981 |
| Grant date | Jan 17, 1984 |
| Priority date | — |
| Expiry date | Oct 29, 2001 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
At a pair of recesses formed on an inner wall of a conduit along a line slanted with respect to the flow direction of a respiration gas flowing through the measuring conduit, a pair of ultrasonic transducers are provided with their ultrasonic transmitting and receiving surfaces oppositely facing each other along the above line. A propagating time T1 from the time when one of said ultrasonic transducers is driven to produce ultrasonic wave until the other transducer receives the ultrasonic wave, and a propagating time difference .DELTA.T are measured. A digital processor calculates a flow velocity of the respiration gas using the measured values in accordance with the following equation ##EQU1## where d is a distance between the pair of transducers free from an effect by the flow velocity of the gas; L a distance influenced by the flow velocity of the same; .theta. an angle of the direction of the respiration flow with respect to a line coupling the pair of transducers; .DELTA.T the propagating time difference; and Ta a value obtained by substituting the propagating time difference .DELTA.T from the double (2 T1) of the ultrasonic propagating time T1.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.