US4425805A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Respiration flowmeter
Assignee: Toshiba Corp
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Filing: 1981-10-29
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Granted: 1984-01-17
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Expires: 2001-10-29
Abstract
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 ΔT 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; θ an angle of the direction of the respiration flow with respect to a line coupling the pair of transducers; ΔT the propagating time difference; and Ta a value obtained by substituting the propagating time difference ΔT from the double (2 T1) of the ultrasonic propagating time T1.
Inventors
- 👤 Ichiro Ogura
- 👤 Ayao Itoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:09
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/66; G01F1/667; A; A61; A61B; A61B5/00; A61B5/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
188 words
A respiration flowmeter comprising: a conduit through which expiration and inspiration flow; a pair of recesses formed on an inner wall of the conduit along a line slanted with respect to a flow direction of the respiration gas; a pair of ultrasonic transducers provided in said recesses with their ultrasonic transmitting and receiving surfaces oppositely faced each other along said line; means simultaneously switching said ultrasonic transducers between a drive mode and a receiving mode; digital counting means for measuring either of the two propagating times taken for ultrasonic wave radiated from one of said pair of driven transducers to reach the other transducer and a difference between said two propagating times; means for judging the flow direction of said respiration gas; means for generating a signal for requesting calculation of a flow velocity of the respiration gas every time said pair of transducers are driven; means for storing said flow direction, said two propagation times and said propagation time difference in response to said calculation request signal; and means for calculating and storing a flow rate of said respiration gas on the basis of said stored values.
Claim 2
Dependent Claim
188 words
A respiration flowmeter comprising: a conduit through which expiration and inspiration flow; a pair of recesses formed on an inner wall of the conduit along a line slanted with respect to a flow direction of the respiration gas; a pair of ultrasonic transducers provided in said recesses with their ultrasonic transmitting and receiving surfaces oppositely faced each other along said line; means simultaneously switching said ultrasonic transducers between a drive mode and a receiving mode; digital counting means for measuring either of the two propagating times taken for ultrasonic wave radiated from one of said pair of driven transducers to reach the other transducer and a difference between said two propagating times; means for judging the flow direction of said respiration gas; means for generating a signal for requesting calculation of a flow velocity of the respiration gas every time said pair of transducers are driven; means for storing said flow direction, said two propagation times and said propagation time difference in response to said calculation request signal; and means for calculating and storing a flow rate of said respiration gas on the basis of said stored values.
Claim 3
Dependent Claim
27 words
A respiration flowmeter according to claim 1, wherein an electric heater for preventing condensation is provided on the periphery of said conduit and around the ultrasonic transducers.
Claim 4
Dependent Claim
34 words
A respiration flowmeter according to claim 1, wherein said switching means include a circuit which supplies a mask pulse for preventing receiving circuits or waveform shapers from receiving signals when drive circuits are driven.
Claim 5
Dependent Claim
114 words
A respiration flowmeter according to claim 1, wherein said means for calculating and storing said flow rate of respiration gas include an arithmetic processor for obtaining a flow velocity V by executing the following operation ##EQU10## where d is a distance between said pair of transducers free from an effect by the flow velocity of said gas; L a distance influenced by the flow velocity of the same; θ an angle of the direction of the respiration flow with respect to a line coupling said pair of transducers; ΔT the propagating time difference; and Ta a value obtained by subtracting said propagating time difference ΔT from the double of the ultrasonic propagating time T1.
Claim 6
Dependent Claim
87 words
A respiration flowmeter according to claim 1, wherein said digital counting means for measuring either of two propagating times and propagating time difference are composed of a first clock means generating a first clock, a second clock means generating a second clock, a first clock counting means for measuring the propagating time difference by counting the first clock and a second clock counting means for mesuring the propagating times by counting the second clock, the second clock having a frequency lower than that of the first clock.
Claim 7
Dependent Claim
22 words
A respiration flowmeter according to claim 1, wherein an electric heater for preventing condensation is provided on the periphery of said conduit.
Claim 8
Dependent Claim
20 words
A respiration flowmeter according to claim 1, wherein an electric heater for preventing condensation is provided around the ultrasonic transducers.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-16 | 1987-07-18 | 1988-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-16 | 1991-07-18 | 1992-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-16 | 1995-07-18 | 1996-01-17 | $7700.00 | Window Closed / Lapsed |