WO1998027436A1 - Instrument for measuring eddy currents - Google Patents

Instrument for measuring eddy currents Download PDF

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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
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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)
French (fr)
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 JP52724498A priority Critical patent/JP2001506755A/en
Priority to BR9714011-2A priority patent/BR9714011A/en
Publication of WO1998027436A1 publication Critical patent/WO1998027436A1/en

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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.

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  • 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)
  • Investigating Or Analysing Biological Materials (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

The invention relates to an instrument for measuring eddy currents for a tachometer, comprising a radially magnetized permanent magnet (4) and a second axially magnetized permanent magnet (8). The radially magnetized permanent magnet (4) is used to generate eddy currents in an eddy current body (2), which moves a needle (7) placed on a centre arbor (1). The second, axially magnetized permanent magnet (8) is mounted a short distance opposite to a fixed Hall element (10). To generate an especially powerful magnetic field the permanent magnet (4) of the eddy current body (2) is magnetized diametrically. The second permanent magnet (8) comprises several pairs of magnetic poles and permits a high resolution of the angle of rotation of a drive shaft (3).

Description

Beschreibung description
WirbelstrommeßwerkEddy current measuring device
Die Erfindung betrifft ein Wirbelstrommeßwerk, insbesondere für einen Tachometer, mit einem drehfest auf einer Antriebswelle befestigten, radial magnetisierten Permanentmagneten und mit einem glockenförmigen, den Permanentmagneten übergreifenden, drehfest auf einer Zeigerwelle angeordneten Wirbelstromkörper aus einem elektrisch leitenden Material sowie einem Hallelement zur Messung der Drehzahl der Antriebswelle.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.
Solche Wirbelstrommeßwerke werden beispielsweise in Tachometern von Fahrzeugen zur Anzeige einer zu der Drehzahl der Antriebswelle proportionalen Geschwindigkeit und zur Ermittlung der Anzahl der Umdrehungen der Antriebswelle und damit einer zurückgelegten Entfernung eingesetzt und sind damit bekannt. Hierbei erzeugt der Permanentmagnet mit zunehmender Drehzahl der Antriebswelle Wirbelströme in dem Wirbelstromkörper. Das Hallelement steht der dem Wirbelstromkörper abgewandten Seite des Permanentmagneten mit geringem Abstand gegenüber und erzeugt bei einem Vorbeibewegen eines Magnetpolpaares des Permanentmagneten ein elektrisches Signal. Die Anzahl der elektrischen Signale ist proportional zu der Anzahl der Umdrehungen der Antriebswelle.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. Here, 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.
Nachteilig bei dem bekannten Wirbelstrommeßwerk ist, daß der Permanentmagnet in der Regel zylinderförmig gestaltet ist und an seinen Stirnseiten nur ein schwaches magnetisches Feld erzeugt. Die Erfassung von schwachen magnetischen Feldern erfordert den Einsatz von besonders kostenintensiven Hallelementen. Weiterhin ist der Permanentmagnet zur Übertragung eines möglichst starken Magnetfeldes auf den Wirbelstromkörper häufig diametral magnetisiert. Hierdurch läßt sich durch das Hallelement nur eine sehr geringe Auflösung des Drehwinkels der Antriebswelle erzeugen.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. Furthermore, 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.
Der Erfindung liegt das Problem zugrunde, ein Wirbelstrommeßwerk der eingangs genannten Art so zu gestalten, daß es kostengünstig aufgebaut ist und eine möglichst genaue Ermittlung des Drehwinkels der Antriebswelle ermöglicht.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.
Dieses Problem wird erfindungsgemäß dadurch gelöst, daß zumindest ein weiterer Permanentmagnet zur Erregung des Halielementes vorgesehen ist.This problem is solved according to the invention in that at least one further permanent magnet is provided to excite the halo element.
Hierdurch kann man den Permanentmagneten des Wirbelstromkörpers unabhängig von den Erfordernissen des Halielementes zur Erzeugung eines möglichst starken Magnetfeldes beispielsweise diametral magnetisiert. Da das Hallelement einem eigenen oder mehreren Permanentmagneten gegenübersteht, erzeugt es den vorbeibewegten Magnetpolpaaren eindeutig zuzuordnende elektrische Signale. Eine mit dem erfindungsgemäßen Wirbelstrommeßwerk ermittelte Anzahl der Umdrehungen der Antriebswelle ist damit besonders genau. Zur Ermittlung der Anzahl der Umdrehungen der Antriebswelle oder ihres Stellwinkels ist im einfachsten Fall nur ein einziges, besonders kostengünstig gefertigtes Hallelement erforderlich. Die Auflösung des Drehwinkels ist in diesem Fall abhängig von der Anzahl der Magnetpolpaare des Permanentmagneten des Hallsensors.As a result, 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. Since 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.
Zur Erregung des Hallelementes könnte beispielsweise ein einzelner Permanentmagnet an einem Ausleger der Antriebswelle angeordnet sein. Das Wirbelstrommeßwerk läßt sich jedoch gemäß einer vorteilhaften Weiterbildung der Erfindung konstruktiv besonders einfach montieren, wenn der Permanentmagnet des Hallelementes ringförmig die Antriebswelle umschließend gestaltet ist. Zur Erfassung einer vorgesehenen Auflösung des Drehwinkels kann der Permanentmagnet des Hallsensors beispielsweise mehrere an seiner dem Hallelement zugewandten Seite angeordnete Magnetpolpaare aufweisen.To excite the Hall element, for example, a single permanent magnet could be arranged on a cantilever of the drive shaft. According to an advantageous development of the invention, however, 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. To detect an intended resolution of the angle of rotation, 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.
Eine gegenseitige Überlagerung von magnetischen Feldern der beiden Permanentmagnete wird gemäß einer anderen vorteilhaften Weiterbildung der Erfindung zuverlässig vermieden, wenn der Permanentmagnet des Hallelementes auf der dem Permanentmagneten des Wirbelstromkörpers abgewandten Seite axial magnetisiert ist. Hierdurch verlaufen die Feldlini- en der Permanentmagnete um 90° verdreht zueinander, so daß der Permanentmagnet des Wirbelstromkörpers am Hallelement ein wesentlich schwächeres magnetisches Feld aufbaut als der Permanentmagnet des Hallelementes. Fehlmessungen des Hallelementes durch magnetische Felder des Permanentmagneten des Wirbelstromkörpers werden durch diese Gestaltung zuverlässig vermieden.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. As a result, 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.
Das Wirbelstrommeßwerk weist gemäß einer anderen vorteilhaften Weiterbildung der Erfindung besonders kleine Abmessungen auf, wenn der Permanentmagnet des Hallelementes an dem Permanentmagneten des Wirbelstromkörpers anliegt.According to another advantageous development of the invention, 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.
Fehlmessungen des Hallsensors durch eine gegenseitige Überlagerung der magnetischen Felder der Permanentmagnete werden gemäß einer anderen vorteilhaften Weiterbildung der Erfindung weiter verringert, wenn der Permanentmagnet des Hallelementes mit geringem Abstand zu dem Permanentmagneten des Wirbelstromkörpers angeordnet ist.Incorrect measurements of the Hall sensor by mutual superimposition of the magnetic fields of the permanent magnets are further reduced according to another advantageous development of the invention if the permanent magnet of the Hall element is arranged at a short distance from the permanent magnet of the eddy current body.
Das von Permanentmagneten erzeugte magnetische Feld ist umso schwächer und gleichförmiger, je mehr Magnetpolpaare dieser aufweist. Will man den Drehwinkel der Antriebswelle mit einer besonders hohen Auflösung erfassen, könnte man den Permanentmagneten des Hallelementes mit besonders vielen Magnetpolpaaren versehen. Dies erfordert jedoch den Einsatz eines besonders empfindlichen und damit kostenintensiven Hallelementes. Eine besonders hohe Auflösung des Drehwinkels läßt sich gemäß einer anderen vorteilhaften Weiterbildung der Erfindung auch mit weniger empfindlichen und damit kostengünstigen Hallelementen erzeugen, wenn zur Erfassung der Drehzahl oder des Drehwinkels der Antriebswelle mehrere, mit Abstand zueinander angeordnete Hallelemente vorgesehen sind. Der Abstand zweier Hallelemente könnte beispielsweise dem halben Abstand eines Magnetpolpaares entsprechen.The magnetic field generated by permanent magnets is weaker and more uniform the more magnetic pole pairs it has. If you want to record the angle of rotation of the drive shaft with a particularly high resolution, you could provide the permanent magnet of the Hall element with a particularly large number of magnetic pole pairs. However, this requires the use of a particularly sensitive and therefore cost-intensive Hall element. According to another advantageous development of the invention, 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.
Die Erfindung läßt zahlreiche Ausführungsformen zu. Zur weiteren Verdeutlichung ihres Grundprinzips sind zwei davon in der Zeichnung dargestellt und werden nachfolgend beschrieben. Diese zeigt in Figur 1 eine Schnittdarstellung durch ein erfindungsgemäßes Wirbelstrommeßwerk,The invention allows numerous embodiments. To further clarify its basic principle, two of them are shown in the drawing and are described below. This shows in FIG. 1 shows a sectional view through an eddy current measuring device according to the invention,
Figur 2 eine Schnittdarstellung des Wirbelstrommeßwerks aus Fig.1 entlang der Linie II - II,FIG. 2 shows a sectional illustration of the eddy current measuring mechanism from FIG. 1 along the line II-II,
Figur 3 eine weitere Ausführungsform des Wirbelstrommeßwerks.Figure 3 shows another embodiment of the eddy current measuring mechanism.
Die Figur 1 zeigt ein Wirbelstrommeßwerk mit einem auf einer Zeigerwelle 1 befestigten, glockenförmigen Wirbelstromkörper 2. Der Wirbel ström Körper 2 übergreift einen auf einer Antriebswelle 3 befestigten, radial magnetisierten Permanentmagneten 4. Auf der dem Permanentmagneten 4 abgewandten Seite des Wirbelstromkörpers 2 ist ein Rückschlußring 5 angeordnet. Die Zeigerwelle 1 wird von einer Drehfeder 6 in eine Grundstellung vorgespannt und trägt auf ihrem dem Wirbelstromkörper 2 abgewandten Ende einen Zeiger 7. Auf der Unterseite des radial magnetisierten Permanentmagneten 4 ist ein zweiter Permanentmagnet 8 angeordnet, der auf seiner dem radial magnetisierten Permanentmagneten 4 abgewandten Seite mehrere in Figur 2 dargestellte Magnetpolpaare 9 aufweist. Mit geringem Abstand vor dem zweiten Permanentmagneten 8 ist ein Hallelement 10 angeordnet, das bei einem Vorbeibewegen eines der Magnetpolpaare 9 ein elektrisches Signal erzeugt.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. On the side of the eddy current body 2 facing away from the permanent magnet 4 there is a return ring 5 arranged. 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.
Eine Drehung der Antriebswelle 3 und damit des radial magnetisierten Permanentmagneten 4 erzeugt der Winkelgeschwindigkeit des Permanentmagneten 4 entsprechend starke Wirbelströme in dem Wirbelstromkörper 2. Diese Wirbelströme lenken die Zeigerwelle 1 gegen die Kraft der Drehfeder 6 aus. Die Auslenkung des Zeigers 7 ist hierbei abhängig von der Drehzahl der Antriebswelle 3. Die Anzahl der von dem Hallelement 10 erzeugten elektrischen Signale ist das Produkt der Anzahl der Umdrehungen der Antriebswelle 3 und der Anzahl der Magnetpolpaare 9 des zweiten Permanentmagneten 8.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.
Die Figur 2 zeigt in einer Schnittdarstellung des Wirbelstrommeßwerks aus Figur 1 entlang der Linie II - II, daß der zweite Permanentmagnet 8 eine Vielzahl von Magnetpolpaaren 9 trägt und damit eine besonders ho- he Auflösung des Drehwinkels der Antriebswelle 3 ermöglicht. Der Permanentmagnet 4 des Wirbelstromkörpers 2 ist diametral magnetisiert und weist damit nur ein Magnetpolpaar auf. Hierdurch werden in dem Wirbelstromkörper 2 besonders starke Wirbelströme erzeugt.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.
Bei einer in Figur 3 dargestellten Ausführungsform des Wirbelstrommeßwerks ist der zweite Permanentmagnet 8 mit einem geringen Abstand zu dem Permanentmagneten 4 des Wirbelstromkörpers 2 angeordnet. Hierdurch wird eine gegenseitige Überlagerung der magnetischen Felder der Permanentmagnete 4, 8 besonders gering gehalten. Weiterhin hat das Wirbelstrommeßwerk zwei Hallelemente 11 , 12, die mit einem Versatz von einem halben Abstand der Magnetpolpaare des zweiten Permanentmagneten 8 zueinander angeordnet sind. Hierdurch wird die Auflösung des Drehwinkels der Antriebswelle 3 bei gleicher Anzahl der Magnetpolpaare verdoppelt. In an embodiment of the eddy current measuring mechanism shown in FIG. 3, the second permanent magnet 8 is arranged at a short distance from the permanent magnet 4 of the eddy current body 2. As a result, a mutual superimposition of the magnetic fields of the permanent magnets 4, 8 is kept particularly low. Furthermore, 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.

Claims

Patentansprüche claims
1. Wirbelstrommeßwerk, insbesondere für einen Tachometer, mit einem drehfest auf einer Antriebswelle befestigten, radial magnetisierten Permanentmagneten und mit einem glockenförmigen, den Permanentmagneten übergreifenden, drehfest auf einer Zeigerwelle angeordneten Wirbelstromkörper aus einem elektrisch leitenden Material sowie einem Hallelement zur Messung der Drehzahl der Antriebswelle, dadurch gekennzeichnet, daß zumindest ein weiterer Permanentmagnet (8) zur Erregung des Hallelementes (10 - 12) vorgesehen ist.1. eddy current measuring mechanism, in particular for a tachometer, with a radially magnetized permanent magnet fixed on a drive shaft in a rotationally fixed manner and with a bell-shaped eddy current body made of an electrically conductive material and overlapping the permanent magnet on a pointer shaft made of an electrically conductive material and a Hall element for measuring the speed of the drive shaft, characterized in that at least one further permanent magnet (8) is provided to excite the Hall element (10 - 12).
2. Wirbelstrommeßwerk nach Anspruch 1 , dadurch gekennzeichnet, daß der Permanentmagnet (8) des Hallelementes (10 - 12) ringförmig die Antriebswelle (3) umschließend gestaltet ist.2. Eddy current measuring mechanism according to claim 1, characterized in that the permanent magnet (8) of the Hall element (10 - 12) is designed annularly surrounding the drive shaft (3).
3. Wirbelstrommeßwerk nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Permanentmagnet (8) des Hallelementes (10 - 12) auf der dem Permanentmagneten (4) des Wirbelstromkörpers (2) abgewandten Seite axial magnetisiert ist.3. Eddy current measuring mechanism according to claim 1 or 2, characterized in that the permanent magnet (8) of the Hall element (10 - 12) on the permanent magnet (4) of the eddy current body (2) is axially magnetized.
4. Wirbelstrommeßwerk nach zumindest einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Permanentmagnet (8) des Hallelementes (10) an dem Permanentmagneten (4) des Wirbelstromkörpers (2) anliegt.4. Eddy current measuring mechanism according to at least one of the preceding claims, characterized in that the permanent magnet (8) of the Hall element (10) abuts the permanent magnet (4) of the eddy current body (2).
5. Wirbelstrommeßwerk nach zumindest einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Permanentmagnet (8) des Hallelementes (11 , 12) mit geringem Abstand zu dem Permanentmagneten (4) des Wirbelstromkörpers (2) angeordnet ist.5. eddy current measuring mechanism according to at least one of the preceding claims, characterized in that the permanent magnet (8) of the Hall element (11, 12) is arranged at a short distance from the permanent magnet (4) of the eddy current body (2).
6. Wirbelstrommeßwerk nach zumindest einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß zur Erfassung der Drehzahl oder des Drehwinkels der Antriebswelle (3) mehrere, mit Abstand zueinander angeordnete Hallelemente (11 , 12) vorgesehen sind. 6. eddy current measuring mechanism according to at least one of the preceding claims, characterized in that for detecting the speed or the angle of rotation of the drive shaft (3) a plurality of spaced-apart Hall elements (11, 12) are provided.
PCT/EP1997/006772 1996-12-14 1997-12-04 Instrument for measuring eddy currents WO1998027436A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP52724498A JP2001506755A (en) 1996-12-14 1997-12-04 Eddy current measurement mechanism
BR9714011-2A BR9714011A (en) 1996-12-14 1997-12-04 Eddy current measurement mechanism

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19652082.7 1996-12-14
DE1996152082 DE19652082A1 (en) 1996-12-14 1996-12-14 Eddy current measuring device

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WO1998027436A1 true WO1998027436A1 (en) 1998-06-25

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KR (1) KR100733162B1 (en)
CN (1) CN1120374C (en)
BR (1) BR9714011A (en)
DE (1) DE19652082A1 (en)
MY (1) MY128316A (en)
WO (1) WO1998027436A1 (en)

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
US7259556B2 (en) * 2002-08-01 2007-08-21 Melexis Technologies Sa Magnetic field sensor and method for operating the magnetic field sensor
JP2004219383A (en) * 2003-01-17 2004-08-05 Central Japan Railway Co Wheel speed detection system
DE102006047896A1 (en) * 2006-10-10 2008-04-17 Volkswagen Ag Displaying device for instrument cluster of motor vehicle, has magnetofluid arranged between indicator device and stationary part of displaying device, where magnetic field holds magnetofluid that dampens oscillations of displaying device
KR20170131527A (en) * 2015-03-25 2017-11-29 다니엘 루돌프 쿠루겔 Material detection method and material detection apparatus
KR20230053391A (en) 2021-10-14 2023-04-21 현대자동차주식회사 Appatus and method for measuring eddy current loss of magnet

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 (en) * 1994-11-10 1996-05-15 Itt Ind Gmbh Deutsche Rotation transmitter using rotatable magnet systems with magnetic North and South poles

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 (en) 1993-11-20 1995-06-01 Vdo Schindling Eddy current operated measuring mechanism for vehicle tachometer

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 (en) * 1994-11-10 1996-05-15 Itt Ind Gmbh Deutsche Rotation transmitter using rotatable magnet systems with magnetic North and South poles

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

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DE19652082A1 (en) 1998-06-18
BR9714011A (en) 2000-05-09
KR20000057320A (en) 2000-09-15
MY128316A (en) 2007-01-31
KR100733162B1 (en) 2007-06-27
JP2001506755A (en) 2001-05-22
CN1240513A (en) 2000-01-05
CN1120374C (en) 2003-09-03

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