Dual diaphragm differential pressure transducer
First Claim
1. A corrosion proof pressure transducer assembly for measuring the pressure difference between two fluids, comprising:
- a central circular insulating base member having a central opening and two spaced flat sides;
first and second thin circular, flat insulating diaphragms having substantially zero mechanical hysteresis, and each having a diameter substantially equal to that of said base member;
means for mounting said diaphragms, one on each side of said base member and spaced apart from said base member by between 0.0005 and 0.010 inch;
a coupling member having substantially the same coefficient of thermal expansion as said insulating base member, mechanically interconnecting the centers of said pair of diaphragms and extending through the central opening in said base member;
facing conductive means in the form of conductive surfaces on the inner surface of one of at least one of said ceramic diaphragms and the adjacent surface of said base member, for forming a variable capacitor having a capacitance which varies as the diaphragms flex;
housing means having first and second input ports for applying fluid pressures from two different sources directly to the outer surfaces of said first and second diaphragms, respectively; and
resilient means mounted near the peripheries of said first and second diaphragms directing and limiting the fluid path from each of said input ports to the associated diaphragm;
whereby the capacitance between said two conductive surfaces is a function of the difference in the fluid pressures applied to said two diaphragms, and said conductive surfaces are isolated from any possible corrosion from the fluids being measured.
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Accused Products
Abstract
A corrosion proof differential pressure transducer includes a central disk and two thin ceramic diaphragms mounted close to but spaced from the disk on both sides thereof, with the diaphragms being intercoupled to move together. This may be accomplished, for example, by a rod passing through a hole in the center of the central disk which is secured to each of the diaphragms; or by a fluid such as silicone oil between the diaphragms and flowing through one or more holes through the central disk. The diaphragm, and disks and the rod are formed of alumina, quartz, or other inert, insulating material having substantially zero mechanical hysteresis. Conductive plates providing variable capacitance with changes in pressure are mounted on the inner surface one or both of the diaphragms and on the facing surface of the central disk. A housing and associated gaskets direct pressures from two different fluids to the two diaphragms, so that the differential pressure is measured.
20 Citations
25 Claims
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1. A corrosion proof pressure transducer assembly for measuring the pressure difference between two fluids, comprising:
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a central circular insulating base member having a central opening and two spaced flat sides; first and second thin circular, flat insulating diaphragms having substantially zero mechanical hysteresis, and each having a diameter substantially equal to that of said base member; means for mounting said diaphragms, one on each side of said base member and spaced apart from said base member by between 0.0005 and 0.010 inch; a coupling member having substantially the same coefficient of thermal expansion as said insulating base member, mechanically interconnecting the centers of said pair of diaphragms and extending through the central opening in said base member; facing conductive means in the form of conductive surfaces on the inner surface of one of at least one of said ceramic diaphragms and the adjacent surface of said base member, for forming a variable capacitor having a capacitance which varies as the diaphragms flex; housing means having first and second input ports for applying fluid pressures from two different sources directly to the outer surfaces of said first and second diaphragms, respectively; and resilient means mounted near the peripheries of said first and second diaphragms directing and limiting the fluid path from each of said input ports to the associated diaphragm; whereby the capacitance between said two conductive surfaces is a function of the difference in the fluid pressures applied to said two diaphragms, and said conductive surfaces are isolated from any possible corrosion from the fluids being measured. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A corrosion-proof pressure transducer assembly for measuring the pressure difference between two fluids, comprising:
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a central insulating base member having at least one opening and two spaced flat sides, said base member having flat sides extending all of the way across both sides thereof; first and second thin flat insulating diaphragms having substantially zero mechanical hysteresis; means for mounting said diaphragms, one on each side of said base member and spaced apart from said base member by between 0.0005 and 0.010 inch, and peripherally secured to said basemember; means for intercoupling said pair of diaphragms and extending through the opening in said base member; means responsive to the flexing of at least one of said diaphragms for producing an electrical output signal proportional to the differential pressure; housing means having first and second input ports for applying fluid pressures from two different sources directly to the outer surfaces of said first and second diaphragms, respectively; resilient peripheral sealing means for sealing against fluid pressure leakage between said housing and the outer edges of said diaphragms; and said assembly including conductive means for shielding said transducer; whereby the electrical output signal is a function of the difference in the fluid pressures applied to said two diaphragms.
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10. A corrosion-proof pressure transducer assembly for measuring the pressure difference between two fluids, comprising:
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a central circular insulating base member having a central opening and two spaced flat sides; first and second thin circular, flat insulating diaphragms having substantially zero mechanical hysteresis, and each having a diameter substantially equal to that of said base member; means for mounting said diaphragms, one on each side of said base member and spaced apart from said base member by between 0.005 and 0.010 inch; a coupling member having substantially the same coefficient of thermal expansion as said insulating base member, mechanically interconnecting the centers of said pair of diaphragms and extending through the central opening in said base member; facing conductive means in the form of conductive surfaces on the inner surface of one of at least one of said diaphragms and the adjacent surface of said base member, for forming a variable capacitor having a capacitance which varies as the diaphragms flex; housing means having first and second input ports for applying fluid pressures from two different sources to the outer surfaces of said first and second diaphragms, respectively; said transducer assembly including an inner metal housing extending around at least the periphery of said diaphragms and base member; whereby the capacitance between said two conductive surfaces is a function of the difference in the fluid pressures applied to said two diaphragms, and said conductive surfaces are isolated from any possible corrosion by the fluids being measured.
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11. A corrosion-proof pressure transducer assembly for measuring the pressure difference between two fluids, comprising:
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a central insulating base member having at least one opening and two spaced flat sides; first and second thin flat insulating diaphragms having substantially zero mechanical hysteresis; means for mounting said diaphragms, one on each side of said base member and spaced apart from said base member by between 0.0005 and 0.010 inch, and peripherally secured to said base member; means for intercoupling said pair of diaphragms and extending through the opening in said base member; facing conductive means in the form of conductive surfaces on the inner surface of one of at least one of said diaphrams and the adjacent surface of said base member, for forming a variable capacitor having a capacitance which varies as the diaphragms flex; enclosing means having first and second input ports for applying fluid pressures from two different sources to the outer surfaces of said first and second diaphragms, respectively; and resilient gasket means for directing fluid pressure from said first and second input ports to the surfaces of the respective first and second diaphragms; whereby the capacitance between said two conductive surfaces is a function of the difference in the fluid pressures applied to said two diaphragms, and said conductive surfaces are isolated from any possible corrosion by the fluids being measured. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A corrosion-proof pressure transducer assembly for measuring the pressure difference between two fluids, comprising:
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a central circular insulating base member having a central opening and two spaced flat sides; first and second thin circular, flat insulating diaphragms having substantially zero mechanical hysteresis, and each having a diameter substantially equal to that of said base member; means for mounting said diaphragms, one on each side of said base member and spaced apart from said base member by between 0.0005 and 0.010 inch; a coupling member having substantially the same coefficient of thermal expansion as said insulating base member, mechanically interconnecting the centers of said pair of diaphragms and extending through the central opening in said base member; facing conductive means in the form of conductive surfaces on the inner surface of one of at least one of said diaphragms and the adjacent surface of said base member, for forming a variable capacitor having a capacitance which varies as the diaphragms flex; housing means having first and second input ports for applying fluid pressures from two different sources to the outer surfaces of said first and second diaphragms, respectively; and first and second resilient rings mounted near the peripheries of said first and second diaphragms directing and limiting the fluid path from each said input ports to the associated diaphragm; whereby the capacitance between said two conductive surfaces is a function of the difference in the fluid pressures applied to said two diaphragms, and said conductive surfaces are isolated from any possible corrosion by the fluids being measured. - View Dependent Claims (25)
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Specification