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US 9,810,567 B2Granted
Calibration-free continuous bin level sensor
AssigneeDickey-john Corporation
InventorBarry C. Mears
Life of this patent
Estimating the term…
Abstract
A sensor assembly is described herein that can automatically calibrate itself upon installation into an empty bin, eliminating the need to actually fill the bin to calibrate the level reading. The sensor will provide consistent measurement regardless of material properties (permittivity, density, temperature or moisture content). The capacitive nature of the sensor means that in some circumstances, it will sense the material through plastic/glass/fiber glass thereby allowing the sensor assembly to be mountable on the outside of a bin or container. The electrodes of the sensor system are designed to provide a continuous level reading.
Claims9
A sensor assembly for measuring the level of a material or fluid in a container or vessel comprising:
- a sensing capacitive element configured from two parallel sensing electrodes positioned adjacent the container or vessel such that changes in a material level cause a proportionate change in a first capacitance of the sensing electrodes, the sensing capacitive element including a first ground electrode and a driven electrode coupled to a first oscillator, wherein said sensing first ground and driven electrodes have a length LL and a nominal capacitance per unit length C0;
- a reference capacitive element configured from two parallel reference electrodes positioned adjacent to a bottom of the container or vessel, the reference capacitive element including a second ground electrode and a second driven electrode coupled to a second oscillator, said reference second ground and driven electrodes having a length LR and a capacitance per unit length C0, wherein said reference electrodes are in contact with the material or fluid within the container;
- and
- an electronics module configured to measure a material or fluid level of the container, said electronics module having at least first and second oscillators, each of said oscillators coupled to a respective amplifier, said electronics module including a processor to process frequency signals received from each of the sensing and reference capacitive elements, each signal of which is a function of electrode capacitance, to be processed by said processor to determine a capacitance for each of said sensing and reference electrodes in each of an empty container and the container having the material or fluid therein, the processor multiplying a ratio of a sensing capacitance to a reference capacitance to a ratio of a length of the reference electrode to the sensing electrode to thereby calculate a level measurement of the material or fluid in the container.
1 more element
A sensor assembly for measuring the level of a material or fluid in a container or vessel comprising:
- a sensing capacitive element configured from two parallel sensing electrodes positioned adjacent the container or vessel such that changes in a material level cause a proportionate change in a first capacitance of the sensing electrodes, wherein said sensing electrodes have a length LL and a nominal capacitance per unit length C0;
- a reference capacitive element configured from two parallel reference electrodes positioned adjacent to a bottom of the container or vessel, said reference electrodes having a length LR and a capacitance per unit length C0, wherein said reference electrodes are in contact with the material or fluid within the container;
- and
- an electronics module configured to measure a material or fluid level of the container, said electronics module having a plurality of oscillators, a plurality of amplifiers and a processor to process signals received from the sensing and reference capacitive elements, wherein said oscillators are configured to be electrically coupled to said sensing and reference electrodes so as to generate a frequency signal to be processed by said processor thereby determining a capacitance of said sensing and reference electrodes to thereby calculate a level measurement of the material or fluid in the container,
- wherein each of the sensing capacitive and reference capacitive elements using multi-frequency measurements are used to determine an empty container capacitance;
- and wherein a total capacitance is determined of the sensing capacitive element and a total reference capacitance of the reference capacitive elements when the reference capacitive element is immersed in the fluid or material;
- and wherein the level of the fluid or material within the container is generated from a product of:
- a ratio of LR (reference electrode length) and LL (sensing electrode length) and
- a ratio of:
- a. a difference of the total capacitance and the empty capacitance of the sensing element as a numerator;
- b. a difference of the total reference capacitance and the empty capacitance of the reference element as a denominator.
8 more elements
A sensor assembly for measuring the level of a material or fluid in a container or vessel comprising:
- a sensing capacitive element configured from two parallel sensing electrodes positioned adjacent the container or vessel such that changes in a material level cause a proportionate change in a first capacitance of the sensing electrodes, wherein said sensing electrodes have a length LL and a nominal capacitance per unit length C0;
- a reference capacitive element configured from two parallel reference electrodes positioned adjacent to a bottom of the container or vessel, said reference electrodes having a length LR and a capacitance per unit length C0, wherein said reference electrodes are in contact with the material or fluid within the container;
- and
- an electronics module configured to measure a material or fluid level of the container, said electronics module having a plurality of oscillators, a plurality of amplifiers and a processor to process signals received from the sensing and reference capacitive elements, wherein said oscillators are configured to be electrically coupled to said sensing and reference electrodes so as to generate a frequency signal to be processed by said processor thereby determining a capacitance of said sensing and reference electrodes to thereby calculate a level measurement of the material or fluid in the container,
- wherein the sensor assembly also determines an empty container capacitance wherein a level measurement (H1/LR) is determined for a non-empty fill level wherein the sensing and reference capacitance at frequency (f1) are determined;
- and wherein a second level measurement (H2/LR) for some non-empty fill level differing from (H1/LR) by at least 10% using the multi-frequency method which includes determination of sensing and reference capacitance at frequency (f2) are determined;
- and
- wherein the empty container reference electrode capacitance is generated from a ratio of:
- a. a difference of the measured capacitance of the sensing element at the first frequency and the measured capacitance of the sensing element at the second frequency as a numerator added to the product of H2/LR and the measured capacitance of the reference element at the second frequency less the product of H1/LR and the measured capacitance of the reference element at the first frequency as a numerator;
- b. a difference of H2/LR and H1/LR as a denominator;
- thereby generating the empty container sensing electrode capacitance from a sum of the total capacitance at the first frequency and the product of H1/LR and the difference of the empty container reference electrode capacitance and the reference capacitance at the first frequency.
8 more elements
Dependencies are inferred from the claim text.