US3901077A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ultrasonic flowmeter
Assignee: National Research Development Corp UK
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Filing: 1974-07-09
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Granted: 1975-08-26
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Expires: 1994-07-09
Abstract
Abstract An ultrasonic flowmeter for measurement of liquid flow volume in a duct, particularly for transcutaneous measurement of blood flow rates, employs a signal of linearly varying frequency to measure the diameter of the blood vessel and the direction of blood flow, and employs a signal of constant frequency to measure the flow velocity. The signal of linearly varying frequency may also be used to determine the flow profile. From this information, the flow volume rate is obtained.
Inventors
- 👤 Kenneth Mccarty
- 👤 John Patrick Woodcock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:26
CPC Classifications
A; A61; A61B; A61B8/00; A61B8/06; G; G01; G01F; G01F1/00; G01F1/66; G01F1/663; Y; Y10; Y10S; Y10S367/00; Y10S367/906
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
108 words
An ultrasonic flowmeter comprising a transmitting transducer, a variable frequency oscillator having its output connected to the input of the transmitting transducer, a receiving transducer arranged to receive reflections and scattering of signals from the transmitting transducer, an audio spectrum analyzer, difference signal means responsive to the receiving transducer for supplying to said audio spectrum analyzer difference signals of frequency equal to the difference between the frequency of the signal transmitted by the transmitting transducer and the reflected and scattered signals received by the receiving transducer, and control means for generating a control signal for the variable frequency oscillator, such control signal comprising periods of linearly varying level.
Claim 2
Dependent Claim
108 words
An ultrasonic flowmeter comprising a transmitting transducer, a variable frequency oscillator having its output connected to the input of the transmitting transducer, a receiving transducer arranged to receive reflections and scattering of signals from the transmitting transducer, an audio spectrum analyzer, difference signal means responsive to the receiving transducer for supplying to said audio spectrum analyzer difference signals of frequency equal to the difference between the frequency of the signal transmitted by the transmitting transducer and the reflected and scattered signals received by the receiving transducer, and control means for generating a control signal for the variable frequency oscillator, such control signal comprising periods of linearly varying level.
Claim 3
Dependent Claim
52 words
An ultrasonic flowmeter as claimed in claim 1 in which the receiving transducer is arranged to receive a signal direct from said transmitting transducer, said difference signal means comprising a filter arranged to reject frequencies in the range of frequencies produced by the variable frequency oscillator and to pass said difference signals.
Claim 4
Dependent Claim
83 words
An ultrasonic flowmeter as claimed in claim 1, in which the difference signal means comprises a mixer having a first input connected to the output of the variable frequency oscillator and a second input connected to the output of the receiving transducer and a filter connecting the output of the mixer to the input of the audio spectrum analyzer and arranged to reject signals of frequency in the range of frequencies produced by the variable frequency oscillator and to pass said difference signals.
Claim 5
Dependent Claim
31 words
An ultrasonic flowmeter as claimed in claim 1, in which the control means is arranged to generate a control signal comprising periods of constant level and periods of linearly varying level.
Claim 6
Dependent Claim
53 words
An ultrasonic flowmeter as claimed in claim 4, in which the receiving transducer is arranged to receive a direct signal from the transmitting transducer and the difference signal means comprises a filter arranged to reject signals in the range of frequencies produced by the variable frequency oscillator and to pass said difference signals.
Claim 7
Dependent Claim
81 words
An ultrasonic flowmeter as claimed in claim 4, in which the difference signal means comprises a mixer having a first input connectEd to the output of the variable frequency oscillator and a second input connected to the output of the receiving transducer and a filter connecting the output of the mixer to the input of the audio spectrum analyzer and arranged to reject signals in the range of frequencies produced by the variable frequency oscillator and to pass said difference signals.
Claim 8
Independent Claim
121 words
A method of measuring the volume flow through a duct employing an ultrasonic flowmeter having a transmitting transducer, a receiving transducer disposed to receive reflection and scattering of signals from said transmitting transducer, an audio spectrum analyzer and means for supplying to said audio spectrum analyzer a difference signal of frequency equal to the difference between the frequency of the signal transmitted by the transmitting transducer and the reflected and scattered signals received by the receiving transducer, comprising successively applying an ultrasonic signal of constant frequency to the transmitting transducer to measure the velocity of flow of liquid in the duct and applying an ultrasonic signal of linearly varying frequency to the transmitting transducer to measure the diameter of the duct.
Claim 9
Independent Claim
121 words
A method of measuring the volume flow through a duct employing an ultrasonic flowmeter having a transmitting transducer, a receiving transducer disposed to receive reflection and scattering of signals from said transmitting transducer, an audio spectrum analyzer and means for supplying to said audio spectrum analyzer a difference signal of frequency equal to the difference between the frequency of the signal transmitted by the transmitting transducer and the reflected and scattered signals received by the receiving transducer, comprising successively applying an ultrasonic signal of constant frequency to the transmitting transducer to measure the velocity of flow of liquid in the duct and applying an ultrasonic signal of linearly varying frequency to the transmitting transducer to measure the diameter of the duct.
Claim 10
Dependent Claim
76 words
A method of measuring the rate of volume flow through a duct as claimed in claim 7, employing a transmitting transducer having a beam width narrower than that diameter of the duct, comprising measuring the range of distances from the transducer over which the flow velocity in the duct is close to maximum while the linearly varying ultrasonic signal is applied to the transmitting transducer, to determine the flow profile of the liquid in the duct.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |