Volume charge density measuring system
First Claim
1. A sensor for testing a material sample, comprising:
- a housing having an electrically conductive shield;
at least one chamber disposed within the housing for containing the material sample, the at least one chamber formed from an electrically non-conductive material and having at least one inlet and at least one outlet for allowing movement of the material sample through the at least one chamber;
at least two electrical conductors corresponding to and disposed on opposite sides of the at least one chamber;
a measurement circuit within the housing coupled to the at least two electrical conductors for producing a measurement signal having a frequency responsive to a capacitance defined by the at least two electrical conductors and the material sample between the at least two electrical conductors, the measurement circuit comprising;
an oscillator circuit coupled to a first electrical conductor of the at least two electrical conductors; and
a circuit ground potential coupled to a second electrical conductor of the at least two electrical conductors; and
at least one of a first electrically-conductive extension and a second electrically-conductive extension, wherein the first electrically-conductive extension is positioned adjacent the at least one inlet, the first electrically-conductive extension having a first end for contacting the material sample in the at least one chamber, and a second end for connecting to a around potential, the first electrically-conductive extension conducting charges within the material sample to the ground potential; and
wherein the second electrically-conductive extension is positioned adjacent the at least one outlet, the second electrically-conductive extension having a first end for contacting the material sample in the at least one chamber, and a second end for connecting to the ground potential, the second electrically-conductive extension conducting the charges within the material sample to the ground potential.
1 Assignment
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Accused Products
Abstract
A capacitive sensor includes one or more chambers through which a material can flow. Two conductors are located to partially surround the flow chamber so that the material flows between the conductors. Where more than one chamber is used, additional conductors are provided. A measurement circuit connected to the conductors provides an output corresponding to a difference between test and reference frequencies. A display indicates the measured capacitance as a continuous-scale, proportional representation or a binary representation. The sensor system can measure volume charge density of a fluid or parameters responsive to changes in volume charge density, such as flow velocity.
35 Citations
20 Claims
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1. A sensor for testing a material sample, comprising:
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a housing having an electrically conductive shield;
at least one chamber disposed within the housing for containing the material sample, the at least one chamber formed from an electrically non-conductive material and having at least one inlet and at least one outlet for allowing movement of the material sample through the at least one chamber;
at least two electrical conductors corresponding to and disposed on opposite sides of the at least one chamber;
a measurement circuit within the housing coupled to the at least two electrical conductors for producing a measurement signal having a frequency responsive to a capacitance defined by the at least two electrical conductors and the material sample between the at least two electrical conductors, the measurement circuit comprising;
an oscillator circuit coupled to a first electrical conductor of the at least two electrical conductors; and
a circuit ground potential coupled to a second electrical conductor of the at least two electrical conductors; and
at least one of a first electrically-conductive extension and a second electrically-conductive extension, wherein the first electrically-conductive extension is positioned adjacent the at least one inlet, the first electrically-conductive extension having a first end for contacting the material sample in the at least one chamber, and a second end for connecting to a around potential, the first electrically-conductive extension conducting charges within the material sample to the ground potential; and
whereinthe second electrically-conductive extension is positioned adjacent the at least one outlet, the second electrically-conductive extension having a first end for contacting the material sample in the at least one chamber, and a second end for connecting to the ground potential, the second electrically-conductive extension conducting the charges within the material sample to the ground potential. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
an inlet endpiece portion attached to the housing to provide an inlet flow channel into the at least one chamber, the inlet endpiece portion comprising;
an inlet bore formed therethrough to the inlet flow channel;
wherein the first electrically-conductive extension is placed in the inlet bore; and
an outlet endpiece portion attached to the housing to provide an outlet flow channel out from the at least one chamber, the outlet endpiece portion comprising;
an outlet bore formed therethrough to the outlet flow channel;
wherein the second electrically-conductive extension is placed in the outlet bore.
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6. The sensor of claim 5,
wherein the first electrically-conductive extension is a first conductive button disposed within the inlet bore for contacting the material sample, the first conductive button comprising: -
an inlet conductor having a first end connected to the first conductive button, and a second end connected to the ground potential, the inlet conductor for conducting the charges within the material sample to the ground potential through the first conductive button; and
wherein the second electrically-conductive extension is a second conductive button disposed within the outlet bore for contacting the material sample, the second conductive button comprising outlet conductor having a first end connected to the second conductive button, and a second end connected to the ground potential, the outlet conductor for conducting the charges within the material sample to the ground potential through the second conductive button.
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7. The sensor of claim 6, wherein one of the first conductive button and the second conductive button is a thermally-conductive button having a hollow interior, the thermally-conductive button further comprising:
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a thermistor disposed within the hollow interior of the thermally-conductive button, the thermistor having a first end and a second end comprising connecting wires;
a thermally-conducting material disposed within the hollow interior of the thermally-conductive button for retaining the first end of the thermistor therein; and
a thermally-insulating material disposed on top of the thermally-conducting material for thermally isolating the first end of the thermistor from the second end;
wherein the second end of the thermistor is connected to the measurement circuit for providing a signal representative of a temperature of the material sample.
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8. The sensor of claim 1, wherein the at least one chamber comprises two chambers, and wherein the at least two electrical conductors comprises three conductors comprising an inner conductor disposed between the two chambers and outer conductors disposed outside of the two chambers.
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9. The sensor of claim 8, wherein the at least one inlet and the at least one outlet of the two chambers are connected to an inlet endpiece and an outlet endpiece, the inlet endpiece and the outlet endpiece each having an axial bore for allowing movement of the material sample through the two chambers.
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10. The sensor of claim 9, wherein the inlet endpiece has an inlet bore formed therethrough for accepting the first electrically-conductive extension, and the outlet endpiece has an outlet bore formed therethrough for accepting the second electrically-conductive extension, wherein each of the first and second electrically-conductive extensions further comprises:
a conductor having a first end connected to the each of the first and second electrically-conductive extensions and a second end connected to the ground potential, the conductor for conducting the charges within the material sample to the ground potential.
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11. The sensor of claim 10, wherein at least one of the first and second electrically-conductive extensions is a thermally-conductive extension, the sensor further comprising:
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a thermistor disposed within a hollow interior of the thermally-conductive extension, the thermistor having a first end and a second end comprising connecting wires;
a thermally-conducting material disposed within the hollow interior of the thermally-conductive extension for retaining the first end of the thermistor therein; and
a thermally-insulating material disposed on top of the thermally-conducting material for thermally isolating the first end of the thermistor from the second end;
wherein the second end of the thermistor is connected to the measurement circuit for providing a signal representative of a temperature of the material sample.
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12. The sensor of claim 8, further comprising a support structure disposed within the housing for supporting each of the two chambers and the three conductors, the support structure comprising axial sidewalls with a plurality of rib structures extending therebetween for providing lateral support, each rib structure of the plurality of rib structures having a cut-out portion for receiving the two chambers and the three conductors.
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13. The sensor of claim 12, further comprising an epoxy material filling at least a portion of the housing and the support structure.
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14. A sensor for measuring a volume charge density of a fluid, the sensor comprising:
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a conductive housing for providing a shield against outside electric fields;
at least one chamber inside of the conductive housing and held by a support structure, the at least one chamber formed from an electrically non-conductive material and providing a flow channel for the fluid;
at least two conductive plates placed on opposite sides of the at least one chamber and held by the support structure;
a measurement circuit coupled to the at least two conductive plates for producing a measurement signal having a frequency responsive to a capacitance defined by the at least two conductive plates and the fluid contained in the flow channel of the at least one chamber, the measurement circuit comprising;
excitation circuitry coupled to a first conductive plate of the at least two conductive plates; and
a circuit ground coupled to a second conductive plate of the at least two conductive plates;
an inlet end piece connected to a first end of the at least one chamber for receiving the fluid into the flow channel;
an outlet end piece connected to a second end of the at least one chamber for discharging the fluid from the flow channel; and
at least one electrically-conductive extension connected to one of the inlet end piece and the outlet end piece, the at least one electrically-conductive extension having a first end for contacting the fluid in the at least one chamber, and a second end for connecting to a ground potential, the at least one electrically-conductive extension conducting a charge within the fluid to the around potential. - View Dependent Claims (15, 16, 17, 18)
wherein at least one of the inlet end piece and the outlet end piece comprises: - a bore extending therethrough to the flow channel; and
wherein the at least one electrically-conductive extension is an electrically-conductive button for placement in the bore, the electrically-conductive button having a first end for contacting the fluid in the flow channel, and a second end for connection to the ground potential, the electrically-conductive button conducting the charge within the fluid to the ground potential.
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16. The sensor of claim 15, wherein the electrically-conductive button is a thermally-conductive button having a hollow interior, the sensor further comprising:
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a thermistor disposed within the hollow interior of the thermally-conductive button, the thermistor coupled to the measurement circuit for providing a signal representative of a temperature of the fluid;
a thermally-conducting material disposed within the hollow interior of the thermally-conductive button for retaining the thermistor therein; and
a thermally-insulating material disposed within said bore on top of the thermally-conducting material for thermally isolating the thermistor from the measurement circuit.
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17. The sensor of claim 14 wherein each of the inlet end piece and the outlet end piece have an interior surface in contact with the fluid in the flow channel and an exterior surface, and wherein at least one of the inlet end piece and the outlet end piece comprises:
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a bore extending from the exterior surface to the interior surface; and
wherein the at least one electrically conductive extension is an electrically-conductive button for placement in the bore, the electrically-conductive button having a first end for contacting the fluid in the flow channel of the at least one chamber, and a second end for connection to the ground potential, the electrically-conductive button conducting the charge within the fluid to the ground potential.
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18. The sensor of claim 17, wherein the electrically-conductive button of at least one of the inlet end piece and the outlet end piece has a hollow interior, the sensor further comprising:
a thermistor disposed within the hollow interior of the electrically-conductive button, the thermistor coupled to the measurement circuit for providing a signal representative of a temperature of the fluid.
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19. A sensor for testing a fluid, the sensor comprising:
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a conductive housing for providing a shield against outside electric fields;
at least one chamber inside of the conductive housing and held by a support structure, the at least one chamber formed from an electrically non-conductive material and providing a flow channel for the fluid;
at least two conductive plates placed on opposite sides of the at least one chamber and held by the support structure;
a measurement circuit coupled to the at least two conductive plates for producing a measurement signal having a frequency responsive to a capacitance defined by the at least two conductive plates and the fluid contained in the flow channel of the at least one chamber;
an inlet end piece connected to a first end of the at least one chamber for receiving the fluid into the flow channel, and an outlet end piece connected to a second end of the at least one chamber for discharging the fluid from the flow channel, each of the inlet end piece and the outlet end piece comprising;
an exterior surface;
an interior surface in contact with the fluid in the flow channel;
a bore extending from the exterior surface to the interior surface; and
an electrically-conductive button for placement in the bore, the electrically-conductive button having a first end for contacting the fluid in the flow channel, and a second end for connection to a ground potential, the electrically-conductive button conducting a charge within the fluid to the ground potential; and
a thermistor disposed within a hollow interior of the electrically-conductive button of at least one of the inlet end piece and the outlet end piece, the thermistor having a lower end adjacent the first end of the electrically conductive button and an upper end comprising connecting wires, wherein the upper end of the thermistor is connected to the measurement circuit for providing a signal representative of a temperature of the fluid. - View Dependent Claims (20)
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Specification