US3901078A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ultrasonic system for fluid flow measurement
Assignee: Rosemount Inc
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Filing: 1973-09-07
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Granted: 1975-08-26
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Expires: 1993-09-07
Abstract
Abstract A simplified ultrasonic flowmeter system in which transmit pulses are applied to each transducer of a pair of transducers aligned with a component of fluid flow in response to a received signal at that transducer. Flip-flop means triggered by successive pulses produces complementary waveforms whose average voltages are subtracted and modified to provide output signals proportional to velocity, Mach number and mass flow rate. The system incorporates automatic speed of sound correction when fluid velocity and mass flow rate are being determined.
Inventors
- 👤 James L Mcshane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:14
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/66; G01F1/667; G01F1/668
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
217 words
In an ultrasonic flowmeter, the combination of at least one pair of transducer means located in acoustic contact with a fluid stream, facing each other and spaced in the path of travel of said fluid stream: first means coupled to a first one of said transducer means located downstream relative to the second one of said transducer means for triggering said first transducer means to transmit an ultrasonic signal upstream in response to a downstream ultrasonic signal received from said second transducer means by said first transducer means. second means coupled to said second transducer means for triggering said second transducer means to transmit an ultrasonic signal downstream in response to an upstream ultrasonic signal received from said first transducer means by said second transducer means. means responsive alternately to said first and second triggering means for deriving a signal representation of a first time interval between the transmission of said upstream ultrasonic signal by said first transducer means and the reception thereof by said second transducer means and of a second time interval between the transmission of said downstream ultrasonic signal by said second transducer means and the reception thereof by said first transducer means; and means responsive to said signal representation deriving means for generating a signal representative of the velocity of said fluid stream.
Claim 2
Dependent Claim
217 words
In an ultrasonic flowmeter, the combination of at least one pair of transducer means located in acoustic contact with a fluid stream, facing each other and spaced in the path of travel of said fluid stream: first means coupled to a first one of said transducer means located downstream relative to the second one of said transducer means for triggering said first transducer means to transmit an ultrasonic signal upstream in response to a downstream ultrasonic signal received from said second transducer means by said first transducer means. second means coupled to said second transducer means for triggering said second transducer means to transmit an ultrasonic signal downstream in response to an upstream ultrasonic signal received from said first transducer means by said second transducer means. means responsive alternately to said first and second triggering means for deriving a signal representation of a first time interval between the transmission of said upstream ultrasonic signal by said first transducer means and the reception thereof by said second transducer means and of a second time interval between the transmission of said downstream ultrasonic signal by said second transducer means and the reception thereof by said first transducer means; and means responsive to said signal representation deriving means for generating a signal representative of the velocity of said fluid stream.
Claim 3
Dependent Claim
97 words
The combination of claim 1 with said signal representation deriving means being responsive to said first and second triggering means for deriving a first signal representative of said first time interval initiated by a pulse transmission concurrently with said first transducer means, and being responsive to said first and second triggering means for deriving a second signal representative of said second time interval initiated by a pulse transmission concurrently with said second transducer means, and with said fluid velocity signal generating means being responsive to said first and second signals for providing said fluid velocity representative signal.
Claim 4
Dependent Claim
104 words
The combination of claim 2 wherein said first and second signals are mutually complementary rectangular waveforms each denoting a succession of rectangular pulses having a width proportional to the one of said first and second time intervals represented by the respEctive signal; wherein said signal representation deriving means include means for deriving signal representations of said pulse widths and wherein said fluid velocity signal generating means include means for subtracting said signal representations to provide a signal whose magnitude is proportional to the difference between the widths of said pulses in the complementary waveforms representing the difference between said first and second time intervals.
Claim 5
Dependent Claim
24 words
The combination of claim 3 with means for correcting said fluid velocity representative signal as a function of sound velocity within said fluid stream.
Claim 6
Dependent Claim
30 words
The combination of claim 3 wherein each of said signal representations is provided by deriving the magnitude of the average value of the corresponding rectangular waveform over a cycle thereof.
Claim 7
Dependent Claim
18 words
The combination of claim 5 with means responsive to said velocity representative signal for indicating the Mach number.
Claim 8
Dependent Claim
81 words
The combination of claim 5 with means for generating a third signal of rectangular waveform denoting a succession of rectangular pulses having a predetermined width, said rectangular pulses of said third signal being recurrently initiated by a selected one of said first and second triggering means; with means responsive to said third signal for deriving a representation of the inverse of the sum of said first and second time intervals, said third signal being applied to said signal representation deriving means.
Claim 9
Dependent Claim
47 words
The combination of claim 7 with said means for deriving a representation of the inverse of the sum of said first and second time intervals comprising means for deriving the magnitude of the average value of the rectangular waveform of said third, signal over a cycle thereof.
Claim 10
Dependent Claim
99 words
The combination of claim 3 with said signal representation deriving means including flip-flop means responsive to triggering of said first and second transducer means to change from one stable state to another when an acoustic signal is transmitted from one of said first and second transducer means and to change from said another state to said one state when an acoustic signal is transmitted from the other of said first and second transducer means thereby to provide at least one signal having a rectangular waveform characterized by said first and second time intervals, as said time interval signal representation.
Claim 11
Dependent Claim
49 words
The combination of claim 9 with said flip-flop means providing two signals in response to triggering of the respective transducer means, said flip-flop means signals having mutually complementary rectangular waveforms, said velocity signal generating means being responsive to the respective first and second time interval characteristics of said waveforms.
Claim 12
Dependent Claim
96 words
The combination of claim 10 with said signal representation deriving means including means for producing a third rectangular waveform of predetermined width each time an ultrasonic signal is transmitted from one of said transducer means, means for producing a voltage whose magnitude is proportional to the average value of said third waveform over a cycle thereof, and means for applying said voltage to said flip-flop means as a source of driving potential, whereby the magnitude of said mutually complementary flip-flop means signals will vary as a function of the speed of sound within said fluid steam.
Claim 13
Dependent Claim
21 words
The combination of claim 11 wherein said fluid velocity signal generating means includes means for providing a voltage Ev proportional to
Claim 14
Dependent Claim
29 words
The combination of claim 10 wherein said signal whose magnitude is proportional to the difference between the widths of the pulses in the complementary waveforms is Em equal to:
Claim 15
Dependent Claim
53 words
The combination of claim 13 including a conduit through which the fluid stream flows, wherein a velocity meter is provided responsive to said velocity representative signal, said velocity meter being calibrated to show directly the volume flow rate Q where Q vA, with A equal to the cross-sectional area A of said conduit.
Claim 16
Dependent Claim
66 words
The combination of claim 1 wherein each of said first and second triggering means includes an amplifier, a pulse generator, a trigger circuit and an hold-off circuit, said trigger circuit being responsive to a received amplified ultrasonic wave for triggering the associated pulse generator and for triggering the associated hold-off circuit to prevent the associated pulse generator from being triggered again for a specific time interval.
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 |