Digital differential pressure measurement apparatus
First Claim
1. Digital pressure differential measurement apparatus comprising:
- a first electromechanical transducer adapted to provide a first series of pulses at a first frequency;
a second electromechanical transducer adapted to provide a second series of pulses at a second frequency, which second frequency is inversely related to a force applied to said second transducer;
force applying means responsive to a pressure differential adapted to apply a force, directly related to said pressure differential, to said second transducer; and
modulator means adapted to receive said first and second series of pulses and to provide a third series of pulses at a third frequency, said third frequency being related to the difference between said first and second frequencies.
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Abstract
Apparatus for measuring a pressure differential in a fluid carrying conduit characterized by a digital representation of the rate of fluid flow and a high degree of accuracy is disclosed. The sensor portion of the apparatus includes two identical electrically driven piezoelectric crystals. One crystal provides a series of pulses at its resonant frequency for use as a reference signal. The second crystal provides a series of pulses at a frequency which is inversely related to a force applied thereto. The sensor further includes two (minimally) arcuately curved stainless steel sealing diaphragms urged in opposing directions by two pressures acting in opposing directions. The movement of the two diaphragms, which are rigidly connected to one another, and which is directly related to the difference in magnitude of the two pressures, is used to apply the force to the second crystal. The pulse trains provided by the first and second crystals are transmitted to a modulator which provides, as its output, a series of pulses at a frequency which is equal to the difference of the frequencies provided by the first and second crystals, this last frequency, which is subsequently provided to utilization apparatus, therefore being directly related to the difference between the first and second pressures.
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Citations
9 Claims
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1. Digital pressure differential measurement apparatus comprising:
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a first electromechanical transducer adapted to provide a first series of pulses at a first frequency; a second electromechanical transducer adapted to provide a second series of pulses at a second frequency, which second frequency is inversely related to a force applied to said second transducer; force applying means responsive to a pressure differential adapted to apply a force, directly related to said pressure differential, to said second transducer; and modulator means adapted to receive said first and second series of pulses and to provide a third series of pulses at a third frequency, said third frequency being related to the difference between said first and second frequencies. - View Dependent Claims (2, 3, 4, 5)
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6. Digital pressure differential measurement apparatus comprising:
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a fluid carrying conduit having a first diameter; constriction means positioned within said conduit, said constriction means having a second diameter smaller than the first diameter, whereby the difference between the fluid pressures at opposite sides of said constriction means is directly related to the flow velocity of said fluids; first pressure responsive means urged in a first direction in response to the fluid pressure at one side of said constriction means; second pressure responsive means urged in a second direction, opposite to said first direction, in response to the fluid pressure at the other side of said constriction means; and means responsive to the location of said first and second pressure responsive means for providing a series of pulses at a frequency directly related to the flow velocity of said fluid, wherein said location responsive means comprises; a first pulse providing means for providing a first series of pulses at a pre-selected frequency; a second pulse providing means for providing a second series of pulses at a frequency related to the location of said first and second pressure responsive means; and modulator means for receiving said first and second series of pulses and for providing a series of pulses at a frequency related to the difference between the frequencies of said first and second series of pulses. - View Dependent Claims (7, 8, 9)
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Specification