US5691484A — Magnetic flow sensor

Claim 1

Independent Claim 110 words

A flow sensor for measuring a rate of flow of an electrically conductive liquid, the sensor comprising: an electrically insulated flow passage; a permanent magnet providing magnetic flux orthogonal to the liquid flow; a pair of electrodes disposed opposite the passage and contacting the liquid, the electrodes being in line with and orthogonal to the flow passage and generally parallel to the magnetic flux, such that said flow passage forms a generally linear fluid flow path; and a mechanical drive for periodically repositioning the magnet to alternate the magnetic flux polarity to produce an alternating voltage at the electrodes having a magnitude proportional to a flow rate of the liquid.

Claim 2

Dependent Claim 110 words

A flow sensor for measuring a rate of flow of an electrically conductive liquid, the sensor comprising: an electrically insulated flow passage; a permanent magnet providing magnetic flux orthogonal to the liquid flow; a pair of electrodes disposed opposite the passage and contacting the liquid, the electrodes being in line with and orthogonal to the flow passage and generally parallel to the magnetic flux, such that said flow passage forms a generally linear fluid flow path; and a mechanical drive for periodically repositioning the magnet to alternate the magnetic flux polarity to produce an alternating voltage at the electrodes having a magnitude proportional to a flow rate of the liquid.

Claim 3

Dependent Claim 19 words

The flow sensor as in claim 1 wherein the mechanical drive for repositioning the magnets includes an electric motor.

Claim 4

Dependent Claim 31 words

The flow sensor as in claim 2 where the permanent magnet has at least two poles and is rotated in a plane parallel to the liquid flow in the flow passage.

Claim 5

Dependent Claim 41 words

The flow sensor as in claim 1 wherein the mechanical drive for repositioning the magnets comprises an electric motor, and the permanent magnet is fixed to a rotating element of the motor and is acted upon electromagnetically to produce the rotation.

Claim 6

Dependent Claim 31 words

A flow sensor as in claim 4 where the permanent magnet has at least two poles and is rotated in a plane parallel to the liquid flow in the flow passage.

Claim 7

Dependent Claim 37 words

The flow sensor as in claim 1 further comprising a second magnet disposed opposite the flow passage from the first magnet so that mutual magnetic attraction exists between the first and second magnets to effect synchronous rotation.

Claim 8

Dependent Claim 31 words

The flow sensor as in claim 6 where the permanent magnet has at least two poles and is rotated in a plane parallel to the liquid flow in the flow passage.

Claim 9

Dependent Claim 60 words

The flow sensor as in claim 6 further comprising: magnet pairs having at least 4 poles of alternating polarity; a plurality of parallel adjacent flow passages; and a third electrode, the third electrode forming a common element between the two adjacent passages to provide an addition of the alternating voltage signal provided by each one of the pair of electrodes.

Claim 10

Dependent Claim 82 words

The flow sensor as in claim 8 further comprising a plurality of flow sensors, coaxially aligned such that the motor driven magnet magnetically attracts and rotates the magnet on the opposite side of its flow passages, the magnetically coupled magnet being mechanically attached to the mechanically driven magnet of a second flow sensor which magnetically attracts and rotates the magnet on the opposite side of its flow passage so that signals from each of the sensors contribute to the overall flow measurement.

Claim 11

Dependent Claim 94 words

A flow sensor for measuring a flow rate of an electrically conductive liquid, the sensor comprising: an electrically insulated flow passage; an electromagnet having a plurality of adjacent poles of opposite polarity and positioned orthogonally with respect to the flow passage; and a pair of electrodes located on opposite sides of the flow passage and positioned in line with and orthogonal to the magnetic flux such that the flow passage forms a generally linear fluid flow path, the electrodes producing an alternating voltage with a magnitude proportional to a flow rate of the liquid.

Claim 12

Dependent Claim 94 words

A flow sensor for measuring a flow rate of an electrically conductive liquid, the sensor comprising: an electrically insulated flow passage; an electromagnet having a plurality of adjacent poles of opposite polarity and positioned orthogonally with respect to the flow passage; and a pair of electrodes located on opposite sides of the flow passage and positioned in line with and orthogonal to the magnetic flux such that the flow passage forms a generally linear fluid flow path, the electrodes producing an alternating voltage with a magnitude proportional to a flow rate of the liquid.

Claim 13

Dependent Claim 40 words

The flow meter as in claim 10 where magnetic material is placed on the side of the flow passages opposite the electromagnet to reduce the magnetic circuit reluctance thereby increasing the magnetic flux and the output signal from the electrodes.

Claim 14

Dependent Claim 125 words

A flow sensor for measuring the flow rate of an electrically conductive liquid, comprising: a plurality of electrically insulated adjacent flow passages; an electromagnet having a plurality of adjacent poles of opposite polarity and providing substantially the same polarity and magnetic flux orthogonal to the liquid flow in both passages; three electrodes in contact with the liquid, first and second ones of the electrodes being located on the outsides of the flow passages in line with and orthogonal to said magnetic flux, the third electrode being common to the flow passages to effect an addition of voltages from the first and second electrodes which alternate at the frequency of the electromagnetic electrical excitation and with a magnitude proportional to the flow rate of said liquid.

Claim 15

Dependent Claim 125 words

A flow sensor for measuring the flow rate of an electrically conductive liquid, comprising: a plurality of electrically insulated adjacent flow passages; an electromagnet having a plurality of adjacent poles of opposite polarity and providing substantially the same polarity and magnetic flux orthogonal to the liquid flow in both passages; three electrodes in contact with the liquid, first and second ones of the electrodes being located on the outsides of the flow passages in line with and orthogonal to said magnetic flux, the third electrode being common to the flow passages to effect an addition of voltages from the first and second electrodes which alternate at the frequency of the electromagnetic electrical excitation and with a magnitude proportional to the flow rate of said liquid.

Claim 16

Dependent Claim 75 words

The flow sensor as in claim 1, further comprising: a second permanent magnet aligned with the permanent magnet to form a pair of permanent magnets and being disposed on opposite sides of the flow path such that the pair of permanent magnets are magnetically attracted to one another; and the pair of permanent magnets being coupled to the mechanical drive so as to be mechanically rotatable by the mechanical drive in unison with each other.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-11-24	2001-05-26	2001-11-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-11-24	2005-05-26	2005-11-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-11-24	2009-05-26	2009-11-25	$7700.00	Window Closed / Lapsed

Magnetic flow sensor

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