EP0264408A1 - Detecteur de proximite par induction - Google Patents

Detecteur de proximite par induction

Info

Publication number
EP0264408A1
EP0264408A1 EP19870902488 EP87902488A EP0264408A1 EP 0264408 A1 EP0264408 A1 EP 0264408A1 EP 19870902488 EP19870902488 EP 19870902488 EP 87902488 A EP87902488 A EP 87902488A EP 0264408 A1 EP0264408 A1 EP 0264408A1
Authority
EP
European Patent Office
Prior art keywords
circuit
proximity sensor
transformer
oscillation
damping
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP19870902488
Other languages
German (de)
English (en)
Inventor
Michael FÖRSTER
Gerhard Weber
Hans Peter Hentzschel
Alfred Leiter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wassermesserfabrik Andrae GmbH and Co
Original Assignee
Wassermesserfabrik Andrae GmbH and Co
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 Wassermesserfabrik Andrae GmbH and Co filed Critical Wassermesserfabrik Andrae GmbH and Co
Publication of EP0264408A1 publication Critical patent/EP0264408A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/06—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects using rotating vanes with tangential admission
    • G01F1/075—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects using rotating vanes with tangential admission with magnetic or electromagnetic coupling to the indicating device
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/4815—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals using a pulse wire sensor, e.g. Wiegand wire
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/488—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by variable reluctance detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
    • G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
    • G01V3/101—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil

Definitions

  • the invention is based on an inductive proximity sensor with the features specified in the preamble of claim 1.
  • a proximity sensor is known from DE-OS 33 18 900. It is a proximity sensor with low power consumption, which has an electrical LC resonant circuit, the coil of which can be influenced by the proximity of an electrically conductive object.
  • the oscillating circuit is excited to oscillate by a direct current pulse and the degree of approximation is deduced from the decay process of the damped oscillation thus generated.
  • This proximity sensor therefore has a relative. low power consumption, because its oscillating circuit is not permanently excited to oscillate by an oscillator, but only by short direct current pulses, which occur at periodic intervals, the time interval of which must be so large that even when the excited oscillation decays slowly (if namely, the attenuator has the least influence on the coil of the resonant circuit) the vibration has already subsided when the next DC pulse occurs.
  • the duration of the DC pulse should be long enough to enable the capacitor of the LC resonant circuit to be sufficiently charged, but it should also be short
  • the oscillating circuit begins to oscillate from the energy stored in the capacitor of the oscillating circuit by means of the direct current pulse.
  • the vibration is damped.
  • the decay time depends on the losses of the resonant circuit, in particular on the losses of the coil of the resonant circuit. If the coil is damped from the outside by the attenuator, the decay time is shortened.
  • the decay process of the damped oscillation can be evaluated in various ways by an evaluation circuit.
  • the voltage at the resonant circuit is decoupled galvanically or inductively and rectified.
  • the mean value of the rectified voltage over the period between two successive DC pulses stimulating the resonant circuit is a measure of the decay period and thus of the respective approach.
  • Another evaluation option mentioned in DE-OS 33 18 900 consists in checking at certain points in time between two successive DC pulses that excite the oscillating circuit whether the oscillation is still ongoing or whether it has already subsided.
  • the current consumption of the proximity sensor is so low that operating times of more than one year can be achieved without changing the battery when feeding from small galvanic elements (button cells).
  • small galvanic elements button cells
  • operating times of more than 5 years without changing the battery are desirable: For example, water meters and heat meters require maintenance-free operation for 5 years. So far, this requirement has not been met with button cells as batteries.
  • the invention is therefore based on the object of further reducing the power consumption in the simplest possible manner in a proximity sensor of the type mentioned at the outset.
  • a further increase in sensitivity of the proximity sensor can be achieved by using a shell core for the transformer; this is a cup-shaped core, in particular made of a ferrite material, with a pin arranged coaxially therein, which carries the two transformer windings.
  • a shell core has a pronounced directional dependency in its sensitivity to vapor deposition from outside: the damping effect is particularly strong when the electrically conductive damping element is brought up to the open end of the shell core. The damping has its cause in eddy currents which are induced in the electrically conductive damping element when it approaches the transformer.
  • the proximity sensor according to the invention is quite insensitive to magnetic interference: when a ferrite approaches the windings, the response signal of the sensor practically does not change. This insensitivity to magnetic interference is an advantage of the proximity sensor according to the invention.
  • the oscillation circuit can be excited by short electrical pulses occurring at equal time intervals, the time interval of the pulses being able to be adapted to the respective intended use of the proximity sensor, taking into account that the time interval of the oscillation circuit stimulating impulses should be at least so large that the excited damped vibrations have at least decayed in this period.
  • An adaptation to different evaluation circuits, which may require different input amplitudes, can be done by adapting the transformation ratio of the transformer.
  • the electrical impulses that excite the resonant circuit do not have to occur periodically ? their occurrence can also be controlled externally, for example as a function of movement sequences in machines or devices in connection with which such a proximity sensor is used.
  • a Wiegand pulse generator is disclosed for example in DE-OS 21 57 286. It has the advantage that it does not require an electrical power source to generate the electrical pulses, so that the power consumption of the sensor can be reduced further (only a power supply is then required for the evaluation circuit.)
  • the nature and particular sensitivity of the proximity sensor according to the invention mean that, despite the extremely low power consumption, numerous periods can still be observed in the decaying oscillation of the oscillating circuit. This enables a particularly elegant development of the invention
  • This threshold is set in such a way that any interference pulses that occur do not contribute to the count result.
  • the count result is a direct measure of the decay - duration of the damped oscillation.
  • the evaluation can be carried out, for example, by evaluating and registering a damping that is clear according to the circumstances of the application as a signal for the approach of the damping element, for example the occurrence of a maximum of 5 periods of the decaying oscillation above the predefinable threshold instead of 10 periods in the undamped Case.
  • the proximity sensor can be used not only as a threshold value detector but also as a displacement sensor.
  • a shell core is used as the transformer core, which gives the sensor a pronounced sensitivity in the direction of the longitudinal axis of the shell core.
  • the particular suitability as a displacement measurement sensor is also directly related to the fact that by using a transformer instead of a single winding in the resonant circuit, the sensitivity of the sensor is increased and the number of periods of decaying vibration in the secondary winding of the transformer is increased. (The secondary winding behaves like an energy store; due to lower damping, the decaying oscillation leads to a greater number of periods).
  • Proximity sensors according to the invention are also particularly suitable for use in a speed sensor in which an attenuator rotating with the speed to be determined approaches the core of the transformer as a result of its rotation and moves away from it. Each approach can be determined by the proximity sensor, reported and then registered.
  • a special application of such a speed sensor equipped according to the invention can be found in water meters and heat meters and other flow meters, which like. these measure the flow of a flowing medium, for example by means of an impeller, and convert it into a rotary movement. Because of the extremely low current consumption of a proximity sensor according to the invention, water meters and the like quantity meters can be operated with a button cell over a period of 5 years and more without changing the batteries.
  • the damping element With a suitable design of the damping element, it is also possible to distinguish between forward and reverse running in such a speed sensor if the damping element is designed asymmetrically with respect to the reversal of the direction of rotation. You could, for example, form the attenuator triangular and lead such that it moves with one of its corners when moving in one direction of rotation approaches the sensitive side of the proximity sensor, while in the opposite direction of rotation it approaches one side of the sensitive side of the proximity sensor. In the first case, the damping starts slower than in the second case, so that in the first case more periods can be counted in the decaying oscillation than in the second case, from which the direction of rotation can be seen.
  • the damping element could be designed in two parts and a first, weakly damping area and a second, strongly damping area could be provided and the two areas separated by an air gap.
  • a first, weakly damping area and a second, strongly damping area could be provided and the two areas separated by an air gap.
  • FIG. 1 shows a longitudinal section through the sensor
  • FIG. 2 shows a view of the opened sensor from the rear
  • Figure 3 shows the arrangement of such a sensor in a water meter
  • Figure 4 shows a block diagram for such a sensor.
  • a transformer with a shell core 2 which has two windings L. and L 2 on top of one another on its central pin 3, one of which is the secondary winding L. has a larger number of windings than the primary winding L,.
  • the pot-type core 2 is arranged so that its open end in the same direction as the Ge 'housing 1 of the sensor with its front end.
  • the shell core 2 is fixed in the housing 1 and protected from the outside by a synthetic resin casting compound 4. In the middle part of the case
  • a circuit board 5 is arranged, which carries the excitation circuit for the oscillator.
  • the excitation circuit are shown in FIG. 1 and in plan view
  • a quartz oscillator 6 with its two connection points 7 and 8; an integrated circuit 9, which forms a pulse signal with a suitable frequency and current strength from the signal of the quartz oscillator by frequency division and signal amplification; the connection points 10 and 11 for a DC voltage source; the connection points 12 and 13 for the primary winding L, and the connection points 14 and
  • the response signal of the proximity sensor is present in the form of a damped oscillation, which is an evaluation circuit is supplied, which can be accommodated on a second circuit board (not shown) in the housing 1, but can also be located outside the housing. In the latter case, a line 15 leads from the connection point 14 to the rear of the housing 1. Above the circuit board 5 there is also space for a button cell 16 for the current supply of the sensor.
  • the button cell 16 is only indicated by dashed lines in FIG. 1.
  • FIG. 1 also shows the connecting lines 17 between the transformer and the printed circuit board 5.
  • the proximity sensor is provided on its front section with an external thread 18, with the aid of which it can be screwed into a suitable bore of a device, for example into the housing of a water meter, as shown in FIG. 3, on a collar surface 19.
  • the water meter shown in FIG. 3 has a housing 20 with an inlet connection 21 and an outlet connection 22.
  • An impeller 23 which is driven by the water flow, is freely rotatably mounted in a measuring chamber lying between these two connections.
  • the impeller is located under a partition wall 24 and is therefore only shown in broken lines.
  • a damping member 25 is freely rotatable about an axis 26 which extends coaxially to the axis of the impeller 23.
  • the damping member 25 rotates synchronously with the impeller 23 and is coupled to it, for example, by means of a contactless magnetic clutch.
  • a proximity sensor 27 according to the invention is also installed in the housing partition 24, in such a way that its longitudinal axis, which coincides with the winding axis, runs parallel to the axis of rotation 26 of the damping element 25.
  • the proximity sensor 27 is arranged in such a way that the damping member 25 is moved once over the front of the proximity sensor during each revolution and damps it in the process.
  • Each passage of the attenuator 25 is recognized on the basis of the damping of the decaying vibration in the proximity sensor and can be registered.
  • the attenuator In order to be able to recognize whether the attenuator runs to the right or to the left, it is designed as a rotating triangular plate which, in the direction of rotation to the right with a tip ahead, approaches the proximity sensor 27, while when it is turned to the left with a radially running side of the triangle the proximity sensor 27 is approximated.
  • the attenuator runs to the right or to the left, it is designed as a rotating triangular plate which, in the direction of rotation to the right with a tip ahead, approaches the proximity sensor 27, while when it is turned to the left with a radially running side of the triangle the proximity sensor 27 is approximated.
  • FIG. 4 shows a block diagram for a proximity sensor as shown in FIGS. 1 and 2 and can be used in a water meter according to FIG.
  • the sensor is operated from a direct current source, in particular from a battery with the battery voltage U ".
  • the excitation circuit for the primary winding L 1 of the transformer comprises a quartz oscillator 30 (shown in FIGS. 1 and 2 and designated by the reference number 6), the output signal of which is fed to a divider circuit 31, which results in a pulse train with a lower pulse frequency forms, which is matched to the respective application of the sensor.
  • the DC voltage pulses coming from the frequency divider circuit 31 are fed after amplification in an amplifier circuit 32 to an LC series resonant circuit consisting of a capacitor C and the winding L ⁇ , which is excited by each of the pulses to a damped oscillation.
  • the damped vibration is transmitted inductively into the secondary winding L 2 of the transformer, the primary winding of which is L.
  • the decay behavior of the damped oscillation occurring in the secondary winding L 2 is observed by an evaluation circuit, which consists of a discriminator circuit 33 and a counter circuit 34.
  • the discriminator circuit 33 gives the U
  • a counter circuit 34 which counts the pulses occurring during each damped oscillation and compares their number with the number of pulses occurring with the undamped sensor and from this comparison concludes the existing or nonexistent damping.
  • the damping events determined by the counter circuit 34 can be fed in a manner known per se to a display or registration device 35, for example a roller counter or a liquid crystal display.
  • a quartz oscillator 30 with a frequency of 32 kHz with low power consumption was selected; a pulse train with a frequency of 256 Hz was formed from the output signal of the quartz crystal 30 by the divider circuit 31. After amplification by the amplifier circuit 32, these pulses had a height of 1 volt at a current of almost 1 ⁇ A.
  • a capacitance of 400 pF was chosen for the capacitor C.
  • the primary winding L. was carried out with 140 turns, the secondary winding L 2 with 800 turns.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Electronic Switches (AREA)

Abstract

Le détecteur de proximité par induction possède un circuit oscillant à cristaux liquides excité par des impulsions électriques et pouvant être amorti par l'approche d'un objet électriquement conducteur, ainsi qu'un circuit d'évaluation (33, 34) permettant de déterminer l'amortissement des oscillations provoqué par l'élément d'amortissement. L'inductance du circuit oscillant à cristaux liquides est produite par l'enroulement primaire (L1) d'un transformateur dont l'enroulement secondaire (L2) présente un nombre de spires supérieur à l'enroulement primaire (L1). Le circuit d'évaluation (33, 34) est situé dans le circuit de l'enroulement secondaire (L2).
EP19870902488 1986-04-09 1987-04-08 Detecteur de proximite par induction Withdrawn EP0264408A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863611862 DE3611862A1 (de) 1986-04-09 1986-04-09 Induktiver naeherungssensor
DE3611862 1986-04-09

Publications (1)

Publication Number Publication Date
EP0264408A1 true EP0264408A1 (fr) 1988-04-27

Family

ID=6298266

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870902488 Withdrawn EP0264408A1 (fr) 1986-04-09 1987-04-08 Detecteur de proximite par induction

Country Status (3)

Country Link
EP (1) EP0264408A1 (fr)
DE (1) DE3611862A1 (fr)
WO (1) WO1987006354A1 (fr)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH672383A5 (fr) * 1986-10-29 1989-11-15 Baumer Electric Ag
DE58903449D1 (de) * 1988-10-27 1993-03-18 Gas & Wassermesserfab Ag Induktiver umdrehungssensor fuer fluegelrad-durchflussmesser.
DE3903278C2 (de) * 1989-02-03 1995-09-28 Rexroth Mannesmann Gmbh Induktive Wegaufnehmeranordnung
DE3923398C1 (fr) * 1989-07-14 1991-01-03 Ziegler, Horst, Prof. Dr., 4790 Paderborn, De
DE4137695C2 (de) * 1991-11-15 1994-12-01 Texas Instruments Deutschland Sensoranordnung zur Feststellung des Bewegungszustandes eines Rotors
DE4239635C2 (de) * 1992-11-23 1998-02-12 Hartmann & Braun Ag Einrichtung zur Wegerfassung von Ventilstangenbewegungen elektropneumatischer Stellungsregler
DE4326030A1 (de) * 1993-08-03 1995-02-09 Klaus Ebinger Verfahren zur elektromagnetischen Detektion von Objekten
US5952822A (en) * 1996-10-24 1999-09-14 Allen-Bradley Company, Llc Method and apparatus for proximity sensing in the presence of an external field
DE19946917A1 (de) * 1999-09-30 2001-04-12 Abb Research Ltd Näherungssensor mit geringer Leistungsaufnahme
DE10125278C2 (de) * 2001-05-23 2003-04-10 Cherry Gmbh Induktive Positionsschaltvorrichtung
EP1296160A1 (fr) * 2001-09-21 2003-03-26 Senstronic (Société Anonyme) Commutateur de proximité inductif
DE102005046331A1 (de) * 2005-09-27 2007-03-29 Endress + Hauser Flowtec Ag Vorrichtung zur Bestimmung und/oder Überwachung einer Prozessgröße
DE102008039377A1 (de) * 2008-08-22 2010-02-25 Hengstler Gmbh Vorrichtung zur Abtastung der Teilstriche eines mechanischen Rollenzählwerks bei Zählern aller Art
DE102010005231A1 (de) 2010-01-21 2011-07-28 M & FC Holding LLC, N.C. Verfahren zum Detektieren der Rotationen eines Rotors
AT510531A1 (de) * 2010-10-05 2012-04-15 Kral Ag Durchflussmesseinrichtung
WO2019210459A1 (fr) * 2018-05-02 2019-11-07 Bently Nevada, Llc Détection d'inversion de sens pour machine rotative

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Publication number Priority date Publication date Assignee Title
US3328680A (en) * 1964-09-11 1967-06-27 Hancock Telecontrol Corp Magnetic detector for sensing the proximity of a metallic object
DE1762565A1 (de) * 1968-07-09 1970-07-02 Bosch Gmbh Robert Elektronischer Naeherungsschalter
FR2048859A5 (fr) * 1969-06-13 1971-03-19 Solvay
FR2181174A7 (fr) * 1972-04-18 1973-11-30 Crouzet Sa
JPS54177960U (fr) * 1978-06-02 1979-12-15
DE2826608A1 (de) * 1978-06-19 1980-01-03 Bosch Gmbh Robert Einrichtung zur abgabe von impulsen bei der vorbeibewegung von zwei relativ zueinander bewegbaren teilen
US4309628A (en) * 1980-02-22 1982-01-05 The Echlin Manufacturing Company Pulse generation by changing magnetic field
GB2102129A (en) * 1981-07-17 1983-01-26 Flight Refueling Ltd Fluid flow meters using Wiegand effect devices
DE3244507C2 (de) * 1981-12-08 1986-02-27 Werner Turck Gmbh & Co Kg, 5884 Halver Magnetfeldabhängiger induktiver Näherungsschalter
DE3318900A1 (de) * 1983-05-25 1984-11-29 Werner Turck Gmbh & Co Kg, 5884 Halver Annaeherungsschalter mit minimalem strombedarf

Non-Patent Citations (1)

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Title
See references of WO8706354A1 *

Also Published As

Publication number Publication date
DE3611862A1 (de) 1987-10-15
WO1987006354A1 (fr) 1987-10-22

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Inventor name: FOERSTER, MICHAEL