WO2002001161A2 - Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement - Google Patents

Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement Download PDF

Info

Publication number
WO2002001161A2
WO2002001161A2 PCT/US2001/020063 US0120063W WO0201161A2 WO 2002001161 A2 WO2002001161 A2 WO 2002001161A2 US 0120063 W US0120063 W US 0120063W WO 0201161 A2 WO0201161 A2 WO 0201161A2
Authority
WO
WIPO (PCT)
Prior art keywords
signal conditioning
conditioning means
transducer
coupled
terminal block
Prior art date
Application number
PCT/US2001/020063
Other languages
English (en)
Other versions
WO2002001161A3 (fr
Inventor
Paul Rudewicz
Michael Vasquez
Original Assignee
Kaiser Electroprecision
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kaiser Electroprecision filed Critical Kaiser Electroprecision
Priority to EP01948649A priority Critical patent/EP1297312A2/fr
Priority to AU2001270103A priority patent/AU2001270103A1/en
Priority to IL15385401A priority patent/IL153854A0/xx
Priority to CA002416551A priority patent/CA2416551A1/fr
Publication of WO2002001161A2 publication Critical patent/WO2002001161A2/fr
Publication of WO2002001161A3 publication Critical patent/WO2002001161A3/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water 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
    • G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water 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 by measuring variations in capacitance of capacitors
    • G01F23/266—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water 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 by measuring variations in capacitance of capacitors measuring circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water 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
    • G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water 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 by measuring variations in capacitance of capacitors
    • G01F23/268—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water 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 by measuring variations in capacitance of capacitors mounting arrangements of probes

Definitions

  • the present invention relates to apparatus to sense status states in a target system and, more particularly, a sensing device capable of operating in temperature environments that are above or below the specified ambient operating temperatures for such a device.
  • the preferred embodiment of the present invention is directed towards fluid level sensors for fluids contained within a closed vessel.
  • the claimed invention is applicable to any sensor apparatus which is required to operate in an environment that is either above or below specified operating temperature limits.
  • Typical prior art approaches include sticks or probes that can be inserted into a container for the fluids. Where the container is not readily accessible or is in a hostile environment, either because of ambient temperatures or because of other environmental challenges, it has been desirable to provide transducers which can determine fluid level and signal such determinations to a remote instrument that displays fluid level or to an alarm system, in the event that the fluid levels are inadequate according to a predetermined criterion.
  • a lubricating, operating or coolant fluid is involved, rather than a fuel which is depleted during normal operation, it is necessary to know when the fluid levels approach levels that cannot sustain adequate operation.
  • fluid levels are checked prior to operation of the machinery.
  • fluid levels might be checked, if accessible, during operation or special level sensors can be employed that can function in hostile environments. The need arises as well for sensors monitoring conditions in other devices.
  • What is needed, and what is provided by the present invention is a sensor that can be targeted to a specific system to be monitored and that includes transducing circuitry coupled to the sensor and subjected to the extreme temperatures of the apparatus and the ambient environment.
  • the circuitry using more or less conventional electronic components that are designed to operate in more temperate environments, is kept within tolerable operating temperature limits by heating/cooling elements. These elements may be located in close proximity to said circuitry or may be applied to a closed environment housing said circuitry that is remotely coupled to the sensors.
  • a rugged sensor that can be placed within a target environment and which relies upon electronic circuits to identify system status states within the selected environment and transmit those states to remote displays or information utilization devices, such as a computer or instrument panel.
  • the electronic circuit modules can be mounted adjacent the sensor but can operate within the normal operating parameters of commercial circuits because of various facets of the invention.
  • a capacitive sensor consisting of concentric conductive cylinders is suspended in a fluid reservoir.
  • the capacitance between the cylinders is a function of the dielectric medium that, in one case would be the fluid whose level is being monitored and air or other atmosphere that exists in the absence of fluid.
  • a reference capacitive element is provided to correct for variations in the dielectric coefficient and temperature of the fluid to be measured. If there is no fluid covering the reference capacitor, the circuitry will signal minimum fluid levels. As the fluid level rises, the reference capacitor is affected by the fluid and a baseline signal is generated.
  • the electronic circuitry be positioned as closely to the cylinders as is possible.
  • the electrical signals produced by the circuitry are much less liable to interference or errors in the transmission of data to display or data processing systems.
  • thermoelectric elements that provide refrigeration or heat, depending upon the flow of electrical current applied thereto.
  • thermoelectric modules are commercially available from several sources throughout the world but the modules selected for the present invention are preferably acquired from TELLUREX Corporation of Traverse
  • the electronic circuits are contained within a closed environment and the temperature within the entire closed environment is maintained within pre-determined reasonable operating limits.
  • the closed environment may be either tightly or loosely coupled to the sensors.
  • the temperature of the oil in the tank was approximately 325° F. (or 163 ° C.) With an ambient air temperature of approximately 250° F. (121 ° C), the normal operating limits for electronic components of -55° C. to 125° C. are challenged in that, at best, there is a 4° C. margin, believed to be inadequate when specifying components for an application.
  • thermo electric (Peltier effect) modules is able to lower the temperature of the components by approximately 30° C. bringing operating conditions well within the operational range for reliable operation.
  • thermo electric modules could employ more or larger thermo electric modules to achieve greater temperature reductions.
  • Typical applications in which the present invention would be useful include large diesel engines in earth moving and construction equipment, trucks, busses, locomotives, marine engines, and power generating plants.
  • thermo-electric elements can be used in heating as well as cooling operations, it is also possible to utilize the present invention in conjunction with equipment that must operate in extremely low temperatures such as are found at high altitudes or in the polar regions where temperatures routinely fall below the lower operating temperature limits for electronic components.
  • FIG. 1 is a sectional view of a tank fitted with a level sensor according to the present invention
  • FIG. 2 is a side view of a capacitive sensor useful in the present invention
  • FIG. 3 is a side sectional view of the sensor of FIG. 2
  • FIG. 4 is side sectional view of a printed circuit board with an incorporated thermo electric element
  • FIG. 4A is side sectional view of a printed circuit board and a thermo electric element contained within a closed environment and remotely coupled to sensor(s)
  • FIG. 5 is a block diagram of an electronic circuit useful in the present invention
  • FIG. 6 including FIGS. 6A and 6B shows typical waveforms with an empty tank
  • FIG. 7, including FIGS. 7A and 7B shows typical waveforms with a full tank.
  • FIG. 1 there is shown, in side section, a tank 10 into which the fluid level sensor 12 of the present invention is installed.
  • the sensor 12 includes a cylindrical capacitive transducer assembly 14 which is located in the interior of the tank 10 and adapted to be in contact with the fluid 16 whose level is to be measured.
  • housing 18 which encloses a printed circuit board assembly 20 that includes a thermo electric element 22.
  • the circuit board assembly 20 is explored in greater detail in FIG.4, below.
  • the transducer assembly 14 includes an inner cylindrical element 26 which includes a lower portion 28 that is insulated and isolated from an upper portion 30 by an insulating collar 32.
  • the transducer assembly 14 also includes an outer cylindrical element 34 that is continuous and uninterrupted.
  • a first conductor 36 is connected to the lower portion 28 and a second conductor 38 is connected to the upper portion 30. Both the first and second conductors are connected to a terminal block 40 that permits electrical connection to the electronic signaling circuits.
  • the sensor system 12 is seen from a side view.
  • An electrical connector 24 is provided so that signals generated within the sensor assembly 12 can be transmitted and power can be applied to the electrical components within the sensor assembly 12.
  • a mounting collar 42 cooperates with mounting elements on the tank structure to install the sensor system 10 in the tank 12.
  • An end cap 44 maintains the spacing between the inner and outer cylindrical elements 26, 34 and admits fluid to the interior of the sensor assembly 10.
  • FIG. 3 the interrelationship between the inner and outer cylindrical elements 26, 34 can be seen in somewhat greater detail.
  • the outer cylindrical element 34 is connected through the mounting collar 42 to a common reference potential source indicated by the ground symbol.
  • the shield of the coaxial cable to the inner cylindrical element 26 is also connected to the source of common reference potential. Accordingly, as the fluid level within the cylindrical elements rises, the capacitance between the inner and outer cylindrical elements changes, as the dielectric value of the fluid is different from that of air.
  • FIG. 4 there is shown in side section, a view of the printed circuit board 50.
  • the printed circuit board components 52 are mounted adjacent a thermally conductive plate 54 to which is mounted the thermo electric elements 56.
  • the cavity 58 between the board 50 and the plate 56 is filled with a compound 60 of high thermal conductivity.
  • the printed circuit board 50 is mounted within a closed environment.
  • Thermo electric elements within the environment are mounted so as to maintain the environment at a temperature that is within the specific normal operating parameters of the circuit board components 52 and the printed circuit board 50.
  • thermo electric elements 56 are connected for cooling so that the circuit board components 52 are kept at a temperature that is well below the ambient temperature of the tank and the fluid contained therein. Knowing the expected ambient temperatures, the thermo electric elements can be selected to provide the desired temperature differential to assure that the components 52 are operating well within their rated temperature ranges.
  • thermo electric elements could function as heaters. This operational mode would increase the temperature of the electronic components to a value that is comfortably within safe operating temperature parameters.
  • FIG. 5 is a block diagram of the electronics that enables the signaling of the fluid levels of the tank 10.
  • a power supply 62 is a source of electrical energy for the system.
  • a voltage regulator 64 reduces the voltage for those circuit elements whose operational requirements mandate a lower voltage.
  • the inner cylindrical sensor element 26 is electrically subdivided into a lower portion 28 and an upper portion 30.
  • the lower portion 28 is connected to a first capacitance driven frequency to voltage converter 66 and the upper portion 30 is connected to a second capacitance driven frequency to voltage converter 68. Both frequency to voltage converters 66, 68 are controlled by a frequency generator 70.
  • the first and second frequency to voltage converters 66, 68 have their outputs applied to an output device 72 which is connected to a differential amplifier 74 which provides an output representative of an accurate oil level reading.
  • the differential amplifier 74 is connected to an output amplifier 76 that transmits a signal to the data management equipment, signaling the fluid level in the tank.
  • FIG. 6 is a graph of typical waveforms for the tank when empty.
  • FIG. 6A is the waveform representing the pulse width input into an averaging filter and
  • FIG. 6B represents the output of the averaging filter.
  • approximately 1/3 or 12.5 microseconds were the duration of a pulse over a period of 40 microseconds.
  • the peak-to-peak voltage was 12.887 volts with an average voltage of 1.1074 volts.
  • the comparable wave forms are shown for a full tank condition.
  • the pulse width is 25 microseconds with the same 40-microsecond period.
  • the 12.5 microsecond difference in pulse width represents the difference between a full and empty tank.
  • the output waveform had a peak to peak voltage of 12.776 volts and an average voltage of 2.1328 volts.
  • the difference of approximately 1.0 volt at the output can be the basis for calibrating the display in that the output voltage represents the volume of fluid in the tank.
  • Known circuits can convert the capacitance value to a pulse width within each period. By averaging the signal, the voltage is proportional to the volume of fluid in the tank.
  • This analog information can be transmitted either in analog or digital form to the information handling systems that will display a reading representative of the amount of fluid in the tank.
  • a sensor designed in the preferred embodiment to sense target states in a system and to work in extreme conditions of heat or cold.
  • a novel capacitive sensor has been disclosed together with a thermo electric module that maintains the electronic circuits at a temperature within normal operating ranges for the electronic components, notwithstanding the extreme ambient temperatures.
  • Signal conditioning means were originally designed.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Or Calibration Of Command Recording Devices (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
  • Measuring Fluid Pressure (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

L'invention concerne un capteur pouvant fonctionner dans des températures ambiantes supérieures ou inférieures à celles comprises dans les spécifications des systèmes de fonctionnement. Ce capteur comprend un transducteur conçu pour être couplé à une alimentation et destiné à générer des signaux correspondant à l'état du système cible et représentatifs de celui-ci. Des dispositifs de mise en forme du signal sont couplés au transducteur et sont sensibles aux signaux générés. Le dispositif de mise en forme du signal produit des signaux d'état dans un format compatible avec un dispositif d'exploitation d'informations. Un module thermoélectrique relié au dispositif de mise en forme du signal permet de modifier la température du dispositif de mise en forme du signal. Dans un autre mode de réalisation, le module thermoélectrique est connecté de façon à réguler l'environnement dans lequel le dispositif de mise en forme du signal fonctionne. Les dispositifs de mise en forme du signal sont alors capables de fonctionner dans des températures ambiantes différentes de celles comprises dans les paramètres de fonctionnement normal, températures pour lesquelles le dispositif de mise en forme du signal à été conçu au départ.
PCT/US2001/020063 2000-06-23 2001-06-22 Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement WO2002001161A2 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP01948649A EP1297312A2 (fr) 2000-06-23 2001-06-22 Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement
AU2001270103A AU2001270103A1 (en) 2000-06-23 2001-06-22 Sensor capable of operating outside of ambient operating temperature limits
IL15385401A IL153854A0 (en) 2000-06-23 2001-06-22 Sensor capable of operating outside of ambient operating temperature limits
CA002416551A CA2416551A1 (fr) 2000-06-23 2001-06-22 Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US21340000P 2000-06-23 2000-06-23
US60/213,400 2000-06-23

Publications (2)

Publication Number Publication Date
WO2002001161A2 true WO2002001161A2 (fr) 2002-01-03
WO2002001161A3 WO2002001161A3 (fr) 2002-04-25

Family

ID=22794972

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/020063 WO2002001161A2 (fr) 2000-06-23 2001-06-22 Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement

Country Status (5)

Country Link
EP (1) EP1297312A2 (fr)
AU (1) AU2001270103A1 (fr)
CA (1) CA2416551A1 (fr)
IL (1) IL153854A0 (fr)
WO (1) WO2002001161A2 (fr)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1578935A (en) * 1976-06-07 1980-11-12 Bunker Ramo Pressure sensor
US4404459A (en) * 1981-10-19 1983-09-13 The Bendix Corporation Housing and mounting assembly providing a temperature stabilized environment for a microcircuit
US4806847A (en) * 1986-12-09 1989-02-21 Caterpillar Inc. Dielectric liquid level sensor and method
US4850227A (en) * 1987-12-22 1989-07-25 Delco Electronics Corporation Pressure sensor and method of fabrication thereof
EP0635137A4 (fr) * 1992-11-13 1995-04-19 Western Atlas Int Inc Base de temps stabilisee par rapport aux temperatures elevees.
US5808206A (en) * 1996-01-16 1998-09-15 Mks Instruments, Inc. Heated pressure transducer assembly
US5659270A (en) * 1996-05-16 1997-08-19 Motorola, Inc. Apparatus and method for a temperature-controlled frequency source using a programmable IC
US5729181A (en) * 1996-08-23 1998-03-17 Hewlett-Packard Company High thermal gain oven with reduced probability of temperature gradient formation for the operation of a thermally stable oscillator

Also Published As

Publication number Publication date
AU2001270103A1 (en) 2002-01-08
EP1297312A2 (fr) 2003-04-02
WO2002001161A3 (fr) 2002-04-25
IL153854A0 (en) 2003-07-31
CA2416551A1 (fr) 2002-01-03

Similar Documents

Publication Publication Date Title
US6973828B2 (en) Liquid level sensor
US9400204B2 (en) Fuel level sensor
CA2280272C (fr) Detecteur capacitif de la contamination et de la deterioration d'une huile de lubrification
CN102183283B (zh) 电容式液位测量探针
US5097703A (en) Capacitive probe for use in a system for remotely measuring the level of fluids
US5449234A (en) Air temperature sensor
US9316543B2 (en) Temperature transmitter transient protector
EP0125366B1 (fr) Capteurs de température
EP0807245B1 (fr) Sonde de temperature
US4713612A (en) Method and apparatus for determination of junction-to-case thermal resistance for a hybrid circuit element
EP2330035A2 (fr) Entrave de sonde de congélation avec socle d'isolation thermique
JP2001524682A (ja) 高感度容量性オイル劣化およびレベルセンサ
US5136998A (en) Automotive control unit with internal sensor
US20040129074A1 (en) Sensor capable of operating outside of ambient operating temperature limits
WO2002001161A2 (fr) Capteur pouvant fonctionner au-dela de ses limites de temperature ambiante de fonctionnement
EP0635137A1 (fr) Base de temps stabilisee par rapport aux temperatures elevees
US20140050248A1 (en) I/o connector incorporating a cold junction
US20160123272A1 (en) Power generator for piston instrumentation
CN212059014U (zh) 一种可测量多个液位耐高温磁致伸缩液位计
Barna et al. An infrared telemetry technique for making piston temperature measurements
JPS58501393A (ja) 液位及び温度センサ
CN210603659U (zh) 一种新型多用温度传感器
CN211527654U (zh) 一种铠装热电阻温度传感器
CN210664813U (zh) 一种防退丝矿用温度传感器
CN110579292A (zh) 一种多用温度传感器

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AU CA IL JP US

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 153854

Country of ref document: IL

WWE Wipo information: entry into national phase

Ref document number: 2416551

Country of ref document: CA

WWE Wipo information: entry into national phase

Ref document number: 2001948649

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2001270103

Country of ref document: AU

WWP Wipo information: published in national office

Ref document number: 2001948649

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 2001948649

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: JP