EP0222798A1 - Agencement a capteur - Google Patents

Agencement a capteur

Info

Publication number
EP0222798A1
EP0222798A1 EP19860902790 EP86902790A EP0222798A1 EP 0222798 A1 EP0222798 A1 EP 0222798A1 EP 19860902790 EP19860902790 EP 19860902790 EP 86902790 A EP86902790 A EP 86902790A EP 0222798 A1 EP0222798 A1 EP 0222798A1
Authority
EP
European Patent Office
Prior art keywords
coil
measuring
measuring tube
sensor arrangement
arrangement according
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Withdrawn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
EP19860902790
Other languages
German (de)
English (en)
Inventor
Klaus Dobler
Hansjörg Hachtel
Karl Roll
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP0222798A1 publication Critical patent/EP0222798A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
    • G01D5/2013—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
    • G01D5/202—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by movable a non-ferromagnetic conductive element

Definitions

  • the invention is based on a sensor arrangement according to the type of the main claim.
  • the sensor consists of a measuring tube and a coil which is wound in one layer and uniformly on a core and is connected to a voltage divider or bridge circuit.
  • This results in an S-shaped calibration curve.
  • their flattening at the beginning and at the end falsifies the measurement result.
  • It is known to linearize the course of the calibration curve with the aid of amplifiers whose amplification factor changes as a function of the input voltage level.
  • each individual sensor type is assigned a specially adapted electronics unit.
  • the amplification factor in electronic units designed in this way is relatively strongly dependent on the level of the ambient temperature because of the necessary connection with non-linear resistors.
  • the sensor arrangement according to the invention with the characterizing features of the main claim has the opposite partly that the calibration curve is almost linear over the entire measuring range. There is therefore always a proportional relationship between the measurement signal change ( ⁇ U M ) and the change in immersion depth ( ⁇ S) of the coil in the measuring tube. This is possible with the help of simple structural measures. Furthermore, even with a constant amplification factor over the almost entire measuring range, ie over the entire coil length, a sufficiently precise proportional measuring voltage (U M ) can be generated at the output of the evaluation circuit.
  • FIG. 1 shows a circuit representation of the exemplary embodiment
  • FIG. 2 shows a section through a sensor arrangement in a simplified representation
  • FIG. 3 shows a non-linear calibration curve according to the prior art
  • FIGS. 4, 5 and 6 each show a modification of the exemplary embodiment according to FIG. 2.
  • FIG. 1 shows an evaluation circuit in which an alternating current generator 10 feeds a measuring coil 11 with a high-frequency alternating current.
  • the measuring coil 1 1 is connected to the series resistor 13 to form a voltage divider 14.
  • a resistor 12 is connected in parallel with the measuring coil 11.
  • a diode 15 is connected in series with the series resistor 13.
  • a capacitor 16 is connected in parallel with the resistor 12.
  • Low-pass filter 19 is connected to the tap of the voltage divider 14 for smoothing the measured values.
  • a conventionally known amplifier circuit 20, which has two resistors 21, 22 and an operational amplifier 23, is connected in series with the low-pass filter 19.
  • a metallic measuring core 26 is shown, which is movable in a measuring tube 27.
  • the measuring tube 27 consists of a tubular carrier element 28, 28a made of non-electrically conductive material and an external tubular body 29.
  • the measuring coil 11 is wound in one layer on the carrier element 28.
  • the inner wall of the tubular body 29 has a central cylindrical region 29b and then two conically widening end regions 29a, 29c.
  • the end region 29a is longer than the end region 29c. This results in different radial distances Y between the measuring coil 11 and the inner wall of the tubular body 29.
  • the measuring coil 11 and the tubular body 29 are arranged in a fixed position relative to one another.
  • the measuring core 26 plunges into the measuring tube 27 and thus into the measuring coil 11, ie the measuring coil 11 and the measuring core 26 are moved relative to one another. Because of the eddy current effect, the alternating current resistance of the measuring coil 11 changes. Eddy currents are formed on the electrically highly conductive surface of the inner wall of the tubular body 29 facing the measuring coil 11, which change the alternating current resistance of the measuring coil 11 and thus the applied voltage, ie the measuring coil 11 becomes subdued. This eddy current formation is - provided a homogeneous magnetic field of the measuring coil - dependent on the size of the air gap, ie on the size of the distance Y.
  • the S-shaped calibration curve 30 shown in FIG. 3 is obtained without damping the coil by the tubular body 29 and shows the course of the applied measuring voltage U M over the immersion depth S of the measuring core in the measuring coil.
  • the flattenings at the beginning and at the end of the calibration curve 30 are caused by the linearity error of the voltage divider 14 or bridge circuit and by the inhomogeneous magnetic field of the measuring coil. This inhomogeneous magnetic field of the measuring coil is due to the lower formation of the magnetic field at the two ends of the measuring coil.
  • the windings of the left and right half of the coil work together to generate the alternating magnetic field, whereas, at the end of the measuring coil, either the windings on the left or right thereof are missing. These deviations from the homogeneity are greater the closer you get to the two coil ends. If the air gap to the measuring tube 27 is enlarged in the two end regions of the measuring coil compared to the central region, the eddy current formation in the end regions is reduced, so that the measuring coil is less damped by the tubular body 29 in the end regions. The measuring coil 11 is therefore less damped in the end regions 29a, 29c with the low magnetic field than in the middle region 29b with the high magnetic field.
  • the magnetic field of the measuring coil 11 can be influenced to such an extent that both the linearity errors of the voltage divider 14 or bridge circuit and the measuring errors of the coil 11 caused by the usually inhomogeneous magnetic field are compensated for.
  • FIG. 4 shows a modification of the exemplary embodiment according to FIG. 2.
  • the measuring coil 11 is wound on a sleeve 35 made of non-electrically conductive material, which is movable in a metallic measuring tube 36.
  • the meas tube 36 has a uniform inner diameter over its entire length.
  • the sleeve 35 has a central region 35b with the same wall thickness and two end regions 35a, 35c which reinforce conically towards the ends of the sleeve 35, so that the openings of the sleeve 35 are reduced.
  • the end region 35c which is first inserted into the measuring tube 36, is shorter than the other end region 35a and has a larger diameter at the end of the sleeve 35.
  • the sleeve 35 is arranged on a metallic core 37, which has the same function as the tubular body 29 in FIG. 2.
  • the measuring coil 11 If the measuring coil 11 is immersed in the measuring tube 36 with the sleeve 35 and the core 37 arranged fixed to it, the measuring coil 11 generates eddy currents on the surface of the core 37 which change the AC resistance of the measuring coil 11. Since in the area 35a, 35c this surface of the core 37 is further away from the measuring coil 11, the eddy current formation in these areas is also less than in the area 35b. As already described above, the measuring coil 11 is damped differently, so that a linear calibration curve is produced at the output of the evaluation circuit.
  • the measuring coil 11 is preferably wound in one layer on a core 40, preferably made of non-electrically conductive material, which is movable in a metal measuring tube 41.
  • the measuring tube 41 itself has a uniform inner diameter over its entire length.
  • a sleeve 42 or 43 made of metallic material is arranged on the inner wall of the measuring tube 41.
  • 3 eide sleeves 42, 43 are conical and each taper towards the opening of the measuring tube 41.
  • the opening diameter of the measuring tube is smaller than its inner diameter in the area Ula between the two sleeves k 2, 43.
  • the sleeve 42 can be made shorter than the sleeve 43. Both Sleeves 42, 43 have approximately the same opening diameter.
  • the S-shaped characteristic curve shown in FIG. 3 is based on the change in the AC resistance of the measuring coil due to the known eddy current effect.
  • the formation of the eddy currents on the metallic inside of the measuring tube 41 can be changed by the sleeves 42, 43 so that the calibration curve in FIG. 3 is almost linear. If the measuring core 40 with the measuring coil 11 is now immersed in the measuring tube 41, the distance Y between the measuring coil 11 and the inside of the measuring tube 41 increases due to the sleeve 42, the deeper the measuring core 40 penetrates into the measuring tube 41. Corresponding to this change in the distance Y, based on the eddy current formation in the measuring tube 41 with a constant inner diameter, more eddy currents are generated.
  • the measuring coil 11 is damped differently and thus the calibration curve is linearized. If the measuring core 40 is located in the region 41a of the measuring tube 41 with a constant inner diameter, i.e. Without an additional sleeve 42, 43, a linear calibration curve is also generated.
  • FIG. 6 shows a reversal of the embodiment of Figure 5.
  • B. PVC, Plexiglas tubular body 45, the measuring coil 11 is wound.
  • a metallic sleeve 47 or 48 is arranged on the metallic measuring core 46 at both ends. Both sleeves 47, 48 are designed to expand conically towards the respective ends of the measuring core 1 + 6.
  • the sleeve 47 which first dips into the tubular body 45, can be shorter than the sleeve 48. Between the two sleeves 47, 48 there is again a region 46a with a constant diameter.
  • the mode of operation when the measuring core 46 is immersed in the tubular body 45 is described analogously to that in FIG. 5.
  • the sleeve 47 corresponds to the sleeve 42 and the sleeve 48 corresponds to the sleeve 43 in their mode of operation.
  • the sensor arrangement can also be operated using the inductive method. The same conditions apply accordingly.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)

Abstract

Une bobine de mesure (11) est incorporée dans un circuit diviseur de tension (14) ou circuit en pont. Elle est enroulée sur un support (28) qui est un bon isolateur électrique et est déplacée par rapport à un noyau de mesure (26). Le support (28) est monté de manière fixe sur la paroi intérieure (29) d'un tube de mesure (27). La paroi intérieure (29), qui est un bon conducteur électrique, possède à ses extrémités des zones évasées (29a, 29c) de sorte que la bobine de mesure (11) est caractérisée par un amortissement différent. La tension enregistrée à la sortie des circuits a ainsi une courbe linéaire caractéristique correspondant au mouvement de la bobine de mesure (11) par rapport au tube de mesure (27). Il est possible de compenser les erreurs de linéarité dans le circuit diviseur de tension (14) ou circuit en pont, ainsi que les erreurs de mesure dans la bobine de mesure (11) dues au champ magnétique non homogène.
EP19860902790 1985-05-24 1986-05-02 Agencement a capteur Withdrawn EP0222798A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3518771 1985-05-24
DE3518771 1985-05-24
DE19853534460 DE3534460A1 (de) 1985-05-24 1985-09-27 Sensoranordnung
DE3534460 1985-09-27

Publications (1)

Publication Number Publication Date
EP0222798A1 true EP0222798A1 (fr) 1987-05-27

Family

ID=25832543

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860902790 Withdrawn EP0222798A1 (fr) 1985-05-24 1986-05-02 Agencement a capteur

Country Status (4)

Country Link
EP (1) EP0222798A1 (fr)
DE (1) DE3534460A1 (fr)
ES (1) ES8704261A1 (fr)
WO (1) WO1986007145A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE141404T1 (de) * 1988-01-22 1996-08-15 Data Instr Inc Linearer weggeber, besonders verwendbar bei hydraulischen und pneumatischen zylindern
GB8809575D0 (en) * 1988-04-22 1988-05-25 Penny & Giles Potentiometers L Linear displacement transducers
GB8810214D0 (en) * 1988-04-29 1988-06-02 Lucas Ind Plc Movement transducer
DE68917314T2 (de) * 1988-10-11 1995-02-23 Radiodetection Ltd Gleichpoliger induktiver verschiebungsfühler.
DE3924327A1 (de) * 1989-04-29 1990-10-31 Teves Gmbh Alfred Wegsensor zur messung mechanischer bewegungsgroessen
DE4328712A1 (de) * 1993-08-26 1995-03-02 Foerster Inst Dr Friedrich Verfahren und Einrichtung zum Prüfen von langgestreckten Gegenständen ggf. mit von der Kreisform abweichendem Querschnitt
DE102010005550A1 (de) 2010-01-22 2011-07-28 Christian-Albrechts-Universität zu Kiel, 24118 Verfahren zur Bestimmung mechanischer Eigenschaften magnetostriktiver Materialien

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3513408A (en) * 1968-08-01 1970-05-19 Tri Metrics Displacement transducer oscillator with movable tapered magnetic core
US3891918A (en) * 1971-03-23 1975-06-24 James F Ellis Linear displacement transducer utilizing an oscillator whose average period varies as a linear function of the displacement
DE2653943C3 (de) * 1976-11-27 1979-05-10 Dieter Hans 8200 Rosenheim Viebach Induktiver Meßwertwandler für Längen- oder WinkelmeBwerte
GB1558206A (en) * 1977-11-02 1979-12-19 Tioxide Group Ltd Position indicator
DE2816596A1 (de) * 1978-04-17 1979-10-25 Vdo Schindling Einrichtung zur beruehrungslosen abnahme eines wegs oder winkels mit einem induktiven stellungsgeber

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8607145A1 *

Also Published As

Publication number Publication date
ES8704261A1 (es) 1987-03-16
WO1986007145A1 (fr) 1986-12-04
DE3534460A1 (de) 1986-11-27
ES555295A0 (es) 1987-03-16

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Inventor name: HACHTEL, HANSJOERG

Inventor name: ROLL, KARL

Inventor name: DOBLER, KLAUS