WO1998027436A1 - Systeme de mesure de courants de foucault - Google Patents

Systeme de mesure de courants de foucault Download PDF

Info

Publication number
WO1998027436A1
WO1998027436A1 PCT/EP1997/006772 EP9706772W WO9827436A1 WO 1998027436 A1 WO1998027436 A1 WO 1998027436A1 EP 9706772 W EP9706772 W EP 9706772W WO 9827436 A1 WO9827436 A1 WO 9827436A1
Authority
WO
WIPO (PCT)
Prior art keywords
permanent magnet
eddy current
hall element
drive shaft
measuring mechanism
Prior art date
Application number
PCT/EP1997/006772
Other languages
German (de)
English (en)
Inventor
Klaus-Jürgen Neidhardt
Original Assignee
Mannesmann Vdo Ag
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 Mannesmann Vdo Ag filed Critical Mannesmann Vdo Ag
Priority to BR9714011-2A priority Critical patent/BR9714011A/pt
Priority to JP52724498A priority patent/JP2001506755A/ja
Publication of WO1998027436A1 publication Critical patent/WO1998027436A1/fr

Links

Classifications

    • 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
    • G01P3/49—Devices characterised by the use of electric or magnetic means for measuring angular speed using eddy currents
    • G01P3/495—Devices characterised by the use of electric or magnetic means for measuring angular speed using eddy currents where the indicating means responds to forces produced by the eddy currents and the generating magnetic field
    • 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
    • G01P3/46—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring amplitude of generated current or voltage
    • G01P3/465—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring amplitude of generated current or voltage by using dynamo-electro tachometers or electric generator
    • 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
    • G01P3/487—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 rotating magnets

Definitions

  • the invention relates to an eddy current measuring mechanism, in particular for a tachometer, with a radially magnetized permanent magnet attached to a drive shaft in a rotationally fixed manner and with a bell-shaped eddy current body made of an electrically conductive material and encompassing the permanent magnets and arranged in a rotationally fixed manner on a pointer shaft, as well as a Hall element for measuring the speed of the Drive shaft.
  • Such eddy current measuring devices are used, for example, in tachometers of vehicles to indicate a speed proportional to the speed of the drive shaft and to determine the number of revolutions of the drive shaft and thus a distance traveled, and are therefore known.
  • the permanent magnet generates eddy currents in the eddy current body with increasing speed of the drive shaft.
  • the Hall element is at a short distance from the side of the permanent magnet facing away from the eddy current body and generates an electrical signal when a pair of magnetic poles of the permanent magnet moves past.
  • the number of electrical signals is proportional to the number of revolutions of the drive shaft.
  • a disadvantage of the known eddy current measuring mechanism is that the permanent magnet is generally cylindrical in shape and generates only a weak magnetic field on its end faces.
  • the detection of weak magnetic fields requires the use of particularly costly Hall elements.
  • the permanent magnet is often diametrically magnetized to transmit the strongest possible magnetic field to the eddy current body. As a result, the Hall element can only produce a very low resolution of the angle of rotation of the drive shaft.
  • the invention is based on the problem of designing an eddy current measuring mechanism of the type mentioned at the outset in such a way that it is constructed inexpensively is and enables the most accurate determination of the angle of rotation of the drive shaft.
  • the permanent magnet of the eddy current body can be diametrically magnetized, for example, independently of the requirements of the halo element in order to generate the strongest possible magnetic field.
  • the Hall element faces its own or several permanent magnets, it generates electrical signals that can be clearly assigned to the magnetic pole pairs that are moving past.
  • a number of revolutions of the drive shaft determined with the eddy current measuring mechanism according to the invention is thus particularly precise. In the simplest case, only a single, particularly inexpensive Hall element is required to determine the number of revolutions of the drive shaft or its actuating angle. In this case, the resolution of the angle of rotation depends on the number of magnetic pole pairs of the permanent magnet of the Hall sensor.
  • the Hall element for example, a single permanent magnet could be arranged on a cantilever of the drive shaft.
  • the eddy current measuring mechanism can be structurally particularly easily installed if the permanent magnet of the Hall element is designed to surround the drive shaft in a ring shape.
  • the permanent magnet of the Hall sensor can have, for example, a plurality of magnetic pole pairs arranged on its side facing the Hall element.
  • a mutual superimposition of magnetic fields of the two permanent magnets is reliably avoided according to another advantageous development of the invention if the permanent magnet of the Hall element is axially magnetized on the side facing away from the permanent magnet of the eddy current body.
  • the field lines en of the permanent magnets rotated by 90 ° to each other, so that the permanent magnet of the eddy current body on the Hall element builds up a much weaker magnetic field than the permanent magnet of the Hall element. Incorrect measurements of the Hall element by magnetic fields of the permanent magnet of the eddy current body are reliably avoided by this design.
  • the eddy current measuring mechanism has particularly small dimensions when the permanent magnet of the Hall element bears against the permanent magnet of the eddy current body.
  • a particularly high resolution of the angle of rotation can also be produced with less sensitive and therefore inexpensive Hall elements if a plurality of Hall elements arranged at a distance from one another are provided for detecting the speed or the angle of rotation of the drive shaft.
  • the distance between two Hall elements could, for example, correspond to half the distance of a pair of magnetic poles.
  • FIG. 1 shows a sectional view through an eddy current measuring device according to the invention
  • FIG. 2 shows a sectional illustration of the eddy current measuring mechanism from FIG. 1 along the line II-II,
  • Figure 3 shows another embodiment of the eddy current measuring mechanism.
  • FIG. 1 shows an eddy current measuring mechanism with a bell-shaped eddy current body 2 attached to a pointer shaft 1.
  • the eddy current body 2 engages over a radially magnetized permanent magnet 4 attached to a drive shaft 3.
  • the pointer shaft 1 is biased into a basic position by a torsion spring 6 and carries a pointer 7 on its end facing away from the eddy current body 2.
  • a second permanent magnet 8 is arranged on the underside of the radially magnetized permanent magnet 4, on its side facing away from the radially magnetized permanent magnet 4 has a plurality of magnetic pole pairs 9 shown in FIG.
  • a Hall element 10 is arranged at a short distance in front of the second permanent magnet 8 and generates an electrical signal when one of the magnetic pole pairs 9 moves past.
  • Rotation of the drive shaft 3 and thus of the radially magnetized permanent magnet 4 generates strong eddy currents in the eddy current body 2 corresponding to the angular velocity of the permanent magnet 4. These eddy currents deflect the pointer shaft 1 against the force of the torsion spring 6. The deflection of the pointer 7 is dependent on the speed of the drive shaft 3.
  • the number of electrical signals generated by the Hall element 10 is the product of the number of revolutions of the drive shaft 3 and the number of magnetic pole pairs 9 of the second permanent magnet 8.
  • FIG. 2 shows in a sectional view of the eddy current measuring mechanism from FIG. 1 along the line II-II that the second permanent magnet 8 carries a multiplicity of magnetic pole pairs 9 and thus a particularly high he resolution of the angle of rotation of the drive shaft 3 enables.
  • the permanent magnet 4 of the eddy current body 2 is magnetized diametrically and thus has only one pair of magnetic poles. As a result, particularly strong eddy currents are generated in the eddy current body 2.
  • the second permanent magnet 8 is arranged at a short distance from the permanent magnet 4 of the eddy current body 2.
  • a mutual superimposition of the magnetic fields of the permanent magnets 4, 8 is kept particularly low.
  • the eddy current measuring mechanism has two Hall elements 11, 12 which are arranged with an offset of half a distance between the magnetic pole pairs of the second permanent magnet 8 from one another. As a result, the resolution of the angle of rotation of the drive shaft 3 is doubled with the same number of magnetic pole pairs.

Landscapes

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

Abstract

L'invention concerne un système de mesure de courants de Foucault pour un tachymètre, qui comprend un aimant permanent (4) magnétisé dans le sens radial et un second aimant permanent (8) magnétisé dans le sens axial. L'aimant permanent (4) magnétisé dans le sens radial sert à produire des courants de Foucault dans un corps à courants de Foucault (2) qui dévie une aiguille (7) placée sur un chevillot (1). Le second aimant permanent (8) magnétisé dans le sens axial est placé de manière opposée à un élément à effet Hall (10) fixe, à faible distance. Pour produire un champ magnétique particulièrement important, l'aimant permanent (4) du corps à courants de Foucault (2) est magnétisé diamétralement. Le second aimant permanent (8) comporte plusieurs paires de pôles magnétiques et permet de parvenir à une haute résolution de l'angle de rotation d'un arbre d'entraînement (3).
PCT/EP1997/006772 1996-12-14 1997-12-04 Systeme de mesure de courants de foucault WO1998027436A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
BR9714011-2A BR9714011A (pt) 1996-12-14 1997-12-04 Mecanismo de medição de correntes parasitas
JP52724498A JP2001506755A (ja) 1996-12-14 1997-12-04 渦電流測定機構

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1996152082 DE19652082A1 (de) 1996-12-14 1996-12-14 Wirbelstrommesswerk
DE19652082.7 1996-12-14

Publications (1)

Publication Number Publication Date
WO1998027436A1 true WO1998027436A1 (fr) 1998-06-25

Family

ID=7814726

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1997/006772 WO1998027436A1 (fr) 1996-12-14 1997-12-04 Systeme de mesure de courants de foucault

Country Status (7)

Country Link
JP (1) JP2001506755A (fr)
KR (1) KR100733162B1 (fr)
CN (1) CN1120374C (fr)
BR (1) BR9714011A (fr)
DE (1) DE19652082A1 (fr)
MY (1) MY128316A (fr)
WO (1) WO1998027436A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150035517A1 (en) * 2013-07-30 2015-02-05 Delphi Technologies, Inc. Vehicle instrument panel with magnet equipped pointer

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1527350A1 (fr) * 2002-08-01 2005-05-04 Sentron Ag Capteur de champ magnetique et procede pour faire fonctionner un tel capteur
JP2004219383A (ja) * 2003-01-17 2004-08-05 Central Japan Railway Co 車輪速度検知システム
DE102006047896A1 (de) * 2006-10-10 2008-04-17 Volkswagen Ag Anzeigeeinrichtung mit einer bewegbaren Zeigereinrichtung und einem Antrieb für die Zeigereinrichtung
CA2980257C (fr) * 2015-03-25 2023-01-24 Daniel Rudolph KRUGEL Procede et dispositif de detection d'un materiau
KR20230053391A (ko) 2021-10-14 2023-04-21 현대자동차주식회사 영구자석 와전류 손실 측정장치 및 방법

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2079473A (en) * 1980-07-03 1982-01-20 Borletti Spa Improvements in a tachometer device controlled by an electric motor
DE4440214A1 (de) * 1994-11-10 1996-05-15 Itt Ind Gmbh Deutsche Drehgeber mit Hallsensoren

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR0108468Y1 (en) * 1993-07-26 1995-02-18 Jung Young Choon Brushless dc motor
DE4339599A1 (de) 1993-11-20 1995-06-01 Vdo Schindling Wirbelstrom-Meßwerk

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2079473A (en) * 1980-07-03 1982-01-20 Borletti Spa Improvements in a tachometer device controlled by an electric motor
DE4440214A1 (de) * 1994-11-10 1996-05-15 Itt Ind Gmbh Deutsche Drehgeber mit Hallsensoren

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150035517A1 (en) * 2013-07-30 2015-02-05 Delphi Technologies, Inc. Vehicle instrument panel with magnet equipped pointer

Also Published As

Publication number Publication date
MY128316A (en) 2007-01-31
JP2001506755A (ja) 2001-05-22
CN1120374C (zh) 2003-09-03
BR9714011A (pt) 2000-05-09
KR100733162B1 (ko) 2007-06-27
DE19652082A1 (de) 1998-06-18
CN1240513A (zh) 2000-01-05
KR20000057320A (ko) 2000-09-15

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