US3885432A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vortex-type mass flowmeters
Assignee: Fischer and Porter Co
•
Filing: 1973-08-02
•
Granted: 1975-05-27
•
Expires: 1993-08-02
Abstract
Abstract A vortex-type mass flowmeter for accurately measuring the mass of fluid passing through a flow tube, the meter being insensitive to background noise resulting from turbulence in the fluid admitted into the flow tube. A bluff body or other means disposed within the tube acts to create a pulsatory fluidic vortex therein whose frequency varies as a function of the volumetric flow rate of the fluid being measured. Placed within the flow tube is a pressure-responsive transducer adapted to generate an electrical signal whose fundamental frequency is proportional to the fluidic pulse rate and whose amplitude is a function of the kinetic energy contained in the vortex. The transducer signal is processed by an operational amplifier, the gain of which is inversely proportional to frequency, thereby effectively dividing the transducer signal by frequency throughout the operating range of the meter to yield an output signal whose amplitude represents mass flow. The output signal is applied to an electronic signal recovery system to filter out all but the fundamental frequency whereby the indicator reading accurately indicates mass flow.
Inventors
- 👤 Peter J Herzl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:01
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/05; G01F1/20; G01F1/32; G01F1/3236
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
186 words
Apparatus for measuring the mass flow of a fluid, said apparatus comprising: A. a vortex meter provided with a flow tube having an obstacle disposed in the flow path of fluid passing through the tube to produce a pulsatory fluidic vortex at a frequency which is a function of flow rate, and a pressure-responsive sensor detecting said fluidic pulses to produce an electrical signal at the same frequency, the amplitude of said signal being a function of the kinetic energy contained in said vortex, B. amplifier means coupled to said sensor and responsive to said electrical signal, said amplifier means having a gain which is inversely proportional to frequency, thereby dividing the electrical signal by frequency to produce an output signal having a fundamental frequency whose amplitude is indicative of mass flow, said output signal having a noise component representing turbulence introduced into said fluid before it enters said flow tube, and C. a signal recovery system coupled to said amplifier means to reject said noise component and to pass only said fundamental frequency to an indicator, whereby an accurate reading of mass flow is obtained.
Claim 2
Dependent Claim
186 words
Apparatus for measuring the mass flow of a fluid, said apparatus comprising: A. a vortex meter provided with a flow tube having an obstacle disposed in the flow path of fluid passing through the tube to produce a pulsatory fluidic vortex at a frequency which is a function of flow rate, and a pressure-responsive sensor detecting said fluidic pulses to produce an electrical signal at the same frequency, the amplitude of said signal being a function of the kinetic energy contained in said vortex, B. amplifier means coupled to said sensor and responsive to said electrical signal, said amplifier means having a gain which is inversely proportional to frequency, thereby dividing the electrical signal by frequency to produce an output signal having a fundamental frequency whose amplitude is indicative of mass flow, said output signal having a noise component representing turbulence introduced into said fluid before it enters said flow tube, and C. a signal recovery system coupled to said amplifier means to reject said noise component and to pass only said fundamental frequency to an indicator, whereby an accurate reading of mass flow is obtained.
Claim 3
Dependent Claim
75 words
A system as set forth in claim 1, wherein said means to reject said noise component is constituted by a phase-sensitive full-wave demodulator coupled to said amplifier means and responsive to said output signal, said demodulator operating in conjunction with a reference frequency source whose frequency corresponds to said fundamental frequency and varies therewith throughout the range of said meter whereby said demodulator rejects said noise component and passes said fundamental frequency to said indicator.
Claim 4
Dependent Claim
51 words
A system as set forth in claim 2, wherein said demodulator includes a pair of electronic switches having separate inputs and a common output which are rendered conductive in phase opposition by said reference frequency source, said output signal being applied to the separate inputs of said switches in phase opposition.
Claim 5
Dependent Claim
29 words
A system as set forth in claim 3, wherein said common output of said switches is coupled to a filter to produce a D-C output voltage representing mass flow.
Claim 6
Dependent Claim
51 words
A system as set forth in claim 4, wherein said reference frequency source includes a voltage-controlled high-frequency oscillator whose output frequency is divided down to produce a reference frequency corresponding to said fundamental frequency, the frequency of said oscillator being governed by a control voltage derived from said flowmeter output signal.
Claim 7
Dependent Claim
70 words
A system as set forth in claim 4, wherein said control voltage is yielded by a mixer, one input of which is a coarse control voltage derived from said output signal through a loop including a Schmitt trigger, the other input of which is a fine control voltage derived from a phase detector which compares the phase of the flowmeter output signal with the phase of the reference frequency source.
Claim 8
Dependent Claim
22 words
A system as set forth in claim 5, wherein the division of said high-frequency is effected by a series of counter stages.
Claim 9
Dependent Claim
27 words
A system as set forth in claim 7 further including a control logic coupled to said stages to produce a reference frequency for operating said phase detector.
References Cited (Backward Citations)
US2897379A
Cited
US3138955A
Cited
US3251226A
Cited
US3355944A
Cited
US3478602A
Cited
US3553566A
Cited
US3659210A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |