Sensor for detecting the level of a medium

Patent metadata

Field	Value
Publication number	US-2017191861-A1
Application number	US-201515315225-A
Country	US
Kind code	A1
Filing date	May 28, 2015
Priority date	May 30, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

A level sensor for detecting the level of a medium contained in a vessel comprises:
an array of capacitive elements designed to be associated with the vessel ( 1 ), comprising a plurality of electrodes (J 1 -J n ), spaced apart from each other along an axis of detection (X), an insulation layer ( 16 ) for electrically insulating the electrodes (Ji-L) with respect to the inside of the vessel ( 1 ), a controller ( 24 ) having a plurality of inputs.

Each capacitive element comprises at least one of a single electrode and a group of electrodes connected in common to each other, the single electrode or the group of electrodes being connected to a respective input of the plurality of inputs.
The controller ( 24 ) is prearranged for discriminating a value of electrical capacitance associated with each electrode (J 1 -J n ) to deduce the level of the medium present in the vessel.

First claim

1 . A level sensor for detecting the level of a medium contained in a vessel, the sensor comprising
an array of capacitive elements designed to be associated with the vessel, in particular to extend according to an axis of detection of the level of the medium, the array of capacitive elements comprising a plurality of electrodes, in particular on a face of an electrically insulating substrate having a generally elongated shape, the electrodes being spaced apart from each other, in particular along the axis of detection, and preferably being essentially coplanar to each other, at least one insulation layer for electrically insulating the electrodes with respect to the inside of the vessel, a controller having a plurality of inputs, wherein each capacitive element comprises at least one of a single electrode and a group of electrodes connected in common to each other particularly in parallel, the single electrode or the group of electrodes being connected to a respective input of the plurality of inputs, and wherein the controller is prearranged for discriminating a value of electrical capacitance associated with each electrode to deduce the level of the medium present in the vessel.

2 . The level sensor according to claim 1 , wherein each capacitive element consists of at least one of a single electrode and a group of electrodes connected in common to each other, particularly in parallel, in such a way that each electrode or group of electrodes realizes an armature of a virtual capacitor, whose other armature is realized by the medium contained in the vessel and wherein the insulation layer realizes the dielectric between the armatures of the aforesaid virtual capacitor,
and wherein the controller is prearranged for carrying out a sequential sampling of the values of electrical capacitance present at the inputs and discriminating thereby a value of electrical capacitance associated to each electrode for deducing the level of the medium present in the vessel.

3 . The level sensor according to claim 1 , wherein each electrode is capable of attaining at least
a first capacitive configuration or structure having a first value of electrical capacitance when the electrode faces the medium, or when the level of the medium in the vessel is at or above the electrode, and a second capacitive configuration or structure having a second value of electrical capacitance when the electrode does not face the medium, or when the level of the medium in the vessel is below the electrode.

4 . The level sensor according to claim 1 , wherein the controller is prearranged for discriminating the value of electrical capacitance associated with each electrode from at least one first and one second value of electrical capacitance, to identify a transition between the medium and air or gas in the vessel, which represents the level of the medium.

5 . The level sensor according to claim 1 , wherein
with each input of the plurality of inputs a circuit, including a controllable switch and a capacitor, is operatively associated, the controllable switch being switchable between a first position, in which the capacitor is connected to a voltage source, and a second position, in which the capacitor is connected to the respective single electrode or group of electrodes and the controller has switching means, for switching the switch from the first position to the second position, in order to discharge the capacitor in a manner proportional to the value of electrical capacitance associated with the corresponding single electrode or group of electrodes.

6 . The level sensor according to claim 2 , wherein
with each input of the plurality of inputs a circuit, including a controllable switch and a capacitor, is operatively associated, the controllable switch being switchable between a first position, in which the capacitor is connected to a voltage source, and a second position, in which the capacitor is connected to the respective single electrode or group of electrodes, and the controller has switching means, for switching the switch from the first position to the second position, in order to discharge the capacitor a manner proportional to the value of electrical capacitance associated with the corresponding single electrode or group of electrodes, where preferably
the controller has:
measuring means, to determine a voltage at said input with the switch in the second position, and
comparator means, to compare the voltage determined at said input with at least one corresponding reference threshold, to deduce if the medium faces or does not face the single electrode or an electrode of the group of electrodes,

each group of electrodes comprises at least one first electrode and one second electrode connected in parallel to each other, and
the comparator means are prearranged to compare the voltage determined at said input with at least two corresponding reference thresholds, in order to deduce if the medium faces or does not face the first electrode and/or the second electrode.

7 . The level sensor according to claim 5 , wherein the controller has:
measuring means, to determine a voltage at said input with the switch in the second position, and comparator means, to compare the voltage determined at said input at least one corresponding reference threshold, to deduce if the medium faces or does not face the single electrode or an electrode of the group of electrodes.

8 . The level sensor according to claim 7 , wherein
each group of electrodes comprises at least one first electrode and one second electrode connected in parallel to each other, and the comparator means are prearranged to compare the voltage determined at said input with at least two corresponding reference thresholds, in order to deduce if the medium faces or does not face the first electrode and/or the second electrode.

9 . The level sensor according to claim 7 , wherein
the reference thresholds are of a number corresponding to the number of electrodes of one said group increased by one, or else of a number corresponding to the number of electrodes of one said group, and the comparator means are prearranged to compare the voltage determined at said input with each of the reference thresholds, to deduce if each one of the electrodes of the said group faces or does not face the medium.

10 . The level sensor according to claim 6 , wherein
the voltage determined at said input is a differential voltage, the measuring means being prearranged for calculating the difference between the voltage value detected at said input and the voltage value detected at an input of the plurality of inputs, which is connected to at least one reference electrode, and the comparator means are prearranged to compare the voltage differential value with said reference threshold or with each of said reference thresholds.

11 . The level sensor according to claim 1 , wherein the electrodes of respective groups form, on a corresponding electrically insulating substrate, respective sub-arrays of electrodes arranged in a sequence along an axis of detection.

12 . The level sensor according to claim 11 , wherein, given a number y of first electrodes connected in parallel to second electrodes between each first electrode and the corresponding second electrode, y−1 electrodes are interposed.

13 . The level sensor according to claim 1 , wherein at least one portion of an electrically insulating substrate (leans against the insulation layer at a face thereof provided with the plurality of electrodes, preferably at least partially in contact with the insulation layer, even more preferably at least at a front of the corresponding electrodes

Assignees

• Eltek Spa

Inventors

• Rondano Matteo
• Chiesa Enrico
• Zorzetto Mauro
• Cantarelli Domenico

Classifications

• G01F23/263

  by measuring variations in capacitance of capacitors · CPC title

• G01F23/26 Primary

  by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields · CPC title

• G01F23/268

  mounting arrangements of probes · CPC title

• G01F23/266

  measuring circuits therefor · CPC title

• G01F23/265 Primary

  for discrete levels · CPC title