Pressure sensor
First Claim
1. A pressure sensor for detecting pressure in a high temperature environment, comprising:
- a cylindrical casing having a diaphragm portion, said diaphragm portion including a cylindrical portion and a closed end integrally connected to one axial end of said cylindrical portion, said cylindrical portion having a thin wall such that said cylindrical portion axially expands and contracts together with said closed end upon being exposed to an external pressure;
a transmission rod received in said cylindrical casing, said transmission rod being engaged at one end with said closed end so that said transmission rod is axially moved upon expansion and contraction of said cylindrical portion of the diaphragm portion;
a stopper fixed in said cylindrical casing in such a manner as to define a given clearance between the stopper and the other end of said transmission rod;
a piezoelectric plate member having opposed electrodes;
a dielectric plate member having opposed electrodes, the capacitance characteristic of said dielectric plate member relative to a temperature being opposite to that of said piezoelectric plate member, said dielectric plate member being directly placed on said piezoelectric plate member in such a manner that one of the electrodes of said dielectric plate member is mated with one of the electrodes of said piezoelectric plate member;
said piezoelectric plate member and said dielectric plate member forming a unit, said unit being located in said given clearance in such a manner that when, due to the axial movement of the cylindrical portion of the diaphragm portion, said transmission rod is moved toward and away from said stopper, said unit is compressed and relaxed in a direction along which said piezoelectric plate member and said dielectric plate member are aligned; and
means for establishing both a first electrical connection between the other electrode of said piezoelectric plate member and an external electric device and a second electrical connection between the other electrode of said dielectric plate member and said external electric device.
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Accused Products
Abstract
A pressure sensor comprises a movable structure which is movable in accordance with a pressure applied thereto. A piezoelectric transducer is employed against which a pressure is applied when the movable structure is moved. The transducer has opposed electrodes between which a voltage is generated when the transducer is pressed. The capacitance between the opposed electrodes increases with increase of temperature. A dielectric member is arranged in the vicinity of the piezoelectric transducer. The dielectric member has opposed electrodes the capacitance between which decreases with increase of temperature. The piezoelectric transducer and the dielectric member are electrically connected in series.
41 Citations
21 Claims
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1. A pressure sensor for detecting pressure in a high temperature environment, comprising:
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a cylindrical casing having a diaphragm portion, said diaphragm portion including a cylindrical portion and a closed end integrally connected to one axial end of said cylindrical portion, said cylindrical portion having a thin wall such that said cylindrical portion axially expands and contracts together with said closed end upon being exposed to an external pressure; a transmission rod received in said cylindrical casing, said transmission rod being engaged at one end with said closed end so that said transmission rod is axially moved upon expansion and contraction of said cylindrical portion of the diaphragm portion; a stopper fixed in said cylindrical casing in such a manner as to define a given clearance between the stopper and the other end of said transmission rod; a piezoelectric plate member having opposed electrodes; a dielectric plate member having opposed electrodes, the capacitance characteristic of said dielectric plate member relative to a temperature being opposite to that of said piezoelectric plate member, said dielectric plate member being directly placed on said piezoelectric plate member in such a manner that one of the electrodes of said dielectric plate member is mated with one of the electrodes of said piezoelectric plate member; said piezoelectric plate member and said dielectric plate member forming a unit, said unit being located in said given clearance in such a manner that when, due to the axial movement of the cylindrical portion of the diaphragm portion, said transmission rod is moved toward and away from said stopper, said unit is compressed and relaxed in a direction along which said piezoelectric plate member and said dielectric plate member are aligned; and means for establishing both a first electrical connection between the other electrode of said piezoelectric plate member and an external electric device and a second electrical connection between the other electrode of said dielectric plate member and said external electric device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A sensor operating in a high temperature environment, comprising:
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a piezoelectric plate member having opposed electrodes; a dielectric plate member having opposed electrodes, a capacitance characteristic of said dielectric plate member relative to a temperature being opposite to a capacitance characteristic of said piezoelectric plate member, said dielectric plate member being directly placed on said piezoelectric plate member in such a manner that one of the opposed electrodes of said dielectric plate member is mated with one of the opposed electrodes of said piezoelectric plate member, said piezoelectric plate member and said dielectric plate member forming a unit; and means for establishing both a first electrical connection between the other of the opposed electrodes of said piezoelectric plate member and an external electric device and a second electrical connection between the other of the opposed electrodes of said dielectric plate member and said external electric device. - View Dependent Claims (18, 19, 20, 21)
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Specification