Magnetic flow sensor
First Claim
1. A flow sensor for measuring a rate of flow of a fluid, the sensor comprising:
- at least one electrically insulated flow passage;
at least a pair of permanent magnets located outside of the flow passage and orthogonal to a direction of the fluid flow and providing magnetic flux orthogonally through the flow passage and the fluid flow;
a drive for mechanically repositioning the magnet to alternate the magnetic flux polarity to produce an alternating voltage having a magnitude proportional to the flow rate of the fluid;
at least two electrically conducting electrodes spaced apart from one another on opposite sides of the flow passage and generally orthogonally to a direction of flow of said fluid, for contacting the fluid and sensing the alternating voltage, said electrodes being located substantially outside the path of magnetic flux generated by said pair of magnets to thereby minimize the generation of voltages at said electrodes, and said electrodes further being symmetrically located with respect to said magnetic flux from said magnets to detect, due to alternation of said magnetic flux through said flow passage, equal voltages of opposite polarity which cancel one another.
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Accused Products
Abstract
Sensors for measuring the flow rate of fluids flowing through or around a chamber. The chamber is formed using electrically insulating material through which there is an orthogonal alternating magnetic field provided by a mechanically repositioned permanent magnet and at least a pair of electrodes in line with and orthogonal to the magnetic field. This provides an electrical potential with a magnitude proportional to flow rate. The alternating magnetic field may also be provided by a stationary multiple electromagnet. Various embodiments are disclosed which make use of electromagnetics, stepper motors and other modifications for adapting the flow sensor to a wide variety of applications and environmental conditions.
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Citations
56 Claims
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1. A flow sensor for measuring a rate of flow of a fluid, the sensor comprising:
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at least one electrically insulated flow passage; at least a pair of permanent magnets located outside of the flow passage and orthogonal to a direction of the fluid flow and providing magnetic flux orthogonally through the flow passage and the fluid flow; a drive for mechanically repositioning the magnet to alternate the magnetic flux polarity to produce an alternating voltage having a magnitude proportional to the flow rate of the fluid; at least two electrically conducting electrodes spaced apart from one another on opposite sides of the flow passage and generally orthogonally to a direction of flow of said fluid, for contacting the fluid and sensing the alternating voltage, said electrodes being located substantially outside the path of magnetic flux generated by said pair of magnets to thereby minimize the generation of voltages at said electrodes, and said electrodes further being symmetrically located with respect to said magnetic flux from said magnets to detect, due to alternation of said magnetic flux through said flow passage, equal voltages of opposite polarity which cancel one another. - View Dependent Claims (3, 4, 5, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 46, 47, 55, 56)
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2. A flow sensor for measuring a rate of flow of a fluid, the sensor comprising:
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at least one electrically insulated flow passage; at least a pair of permanent magnets located outside of the flow passage and orthogonal to a direction of said fluid flow, and providing magnetic flux orthogonally through the flow passage and the fluid flow to generate a voltage in the fluid flow having a magnitude proportional to the flow rate of the fluid flow; at least two electrically conducting electrodes spaced apart from one another on opposite sides of the flow passage and generally orthogonally to a direction of flow of said fluid, for contacting the fluid and sensing the alternating voltage, said electrodes being located substantially outside the path of magnetic flux generated by said pair of magnets to thereby minimize the generation of voltages at said electrodes, and said electrodes further being symmetrically located with respect to said magnetic flux from said magnets to detect, due to alternation of said magnetic flux through said flow passage, equal voltages of opposite polarity which cancel one another, a drive for mechanically repositioning the magnets periodically to prevent the magnetic flux from passing through the flow passage and fluid flow so as to generate a flow related voltage; and means for periodically detecting said electrode voltage and generating an output signal indicative of said fluid flow rate, and for using said detected voltage as a reference in cancelling voltage drifts in said output signal when said electrodes are not sensing said flow related signal. - View Dependent Claims (6, 9)
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41. A flow sensor for measuring a rate of flow of a cyclically flowing fluid, the sensor comprising:
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a housing; at least a pair of permanent magnets associated with said housing and disposed outside of a flow passage of said flowing fluid, and further orthogonal to a direction of said fluid flow, for providing magnetic flux orthogonally through said flowing fluid to generate a voltage in said flowing fluid having a magnitude proportional to the flow rate of said fluid; at least two electrically insulated electrodes associated with said housing which are spaced apart from one another and in contact with said fluid for sensing said voltage, said electrodes being disposed on opposite sides of said flow passage and generally orthogonally to said direction of flow of said flowing fluid, for contacting the fluid and sensing the voltage, said electrodes being located substantially outside the path of magnetic flux generated by said pair of magnets to thereby minimize the generation of voltages at said electrodes, and said electrodes further being symmetrically located with respect to said magnetic flux from said magnets; and means for detecting said voltage and providing an output signal indicative of said fluid flow rate and for detecting said voltage at independently determined said flow rates to be used as a reference for canceling voltage drifts in said output signal. - View Dependent Claims (42)
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43. A flow sensor for measuring the rate of flow of a fluid, the sensor comprising:
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at least one electrically insulated flow passage; at four pairs of alternating polarity magnetic poles disposed around a central rotational axis, and located such that one of each pair of said magnets is disposed on opposite sides of said flow passage and orthogonally to a direction of flow of said fluid flow, and providing magnetic flux orthogonally into the fluid flow; a drive for mechanically repositioning the said magnetic poles to alternate their magnetic polarity across the flow passage to produce an alternating voltage having a magnitude proportional to the flow rate of the fluid; at least two electrically conducting electrodes spaced apart from one another on opposite sides of the flow passage and generally orthogonally to a direction of flow of said fluid, for contacting the fluid and sensing the alternating voltage, said electrodes being located substantially outside the path of magnetic flux generated by said pair of magnets to thereby minimize the generation of voltages at said electrodes, and said electrodes further being symmetrically located with respect to said magnetic flux from said magnets to detect, due to alternation of said magnetic flux through said flow passage, equal voltages of opposite polarity which cancel one another. - View Dependent Claims (44, 45)
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48. A flow sensor for measuring a rate of flow of a fluid, the sensor comprising:
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a housing disposed at least partially within a flow path of said fluid; at least a pair of permanent magnets disposed internally of the sensor for providing magnetic flux orthogonally through said fluid flow; a drive for mechanically repositioning said magnets to alternate the polarity of the magnetic flux to produce an alternating voltage in said fluid having a magnitude proportional to the flow rate of the said fluid; at least two electrically conducting electrodes spaced apart from one another on opposite sides of the flow passage and generally orthogonally to a direction of flow of said fluid, for contacting the fluid and sensing the alternating voltage, said electrodes being located substantially outside the path of magnetic flux generated by said pair of magnets to thereby minimize the generation of voltages at said electrodes, and said electrodes further being symmetrically located with respect to said magnetic flux from said magnets to detect, due to alternation of said magnetic flux through said flow passage, equal voltages of opposite polarity which cancel one another; and a system responsive to said alternating voltage for processing said alternating voltage to produce an electrical signal representative of said rate of flow of said fluid. - View Dependent Claims (49, 50, 51, 52, 53, 54)
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Specification