EP1007909A1 - Detecteur a resonance magnetique - Google Patents

Detecteur a resonance magnetique

Info

Publication number
EP1007909A1
EP1007909A1 EP96946119A EP96946119A EP1007909A1 EP 1007909 A1 EP1007909 A1 EP 1007909A1 EP 96946119 A EP96946119 A EP 96946119A EP 96946119 A EP96946119 A EP 96946119A EP 1007909 A1 EP1007909 A1 EP 1007909A1
Authority
EP
European Patent Office
Prior art keywords
sensor
magnetic
coil
magnetic field
frequency
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Withdrawn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
EP96946119A
Other languages
German (de)
English (en)
Inventor
Ralf VON SCHÄWEN
Jürgen KOBLITZ
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.)
Bic-Neisse GmbH
Original Assignee
Bic-Neisse 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 Bic-Neisse GmbH filed Critical Bic-Neisse GmbH
Publication of EP1007909A1 publication Critical patent/EP1007909A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G01V3/104—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 using several coupled or uncoupled coils
    • G01V3/105—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 using several coupled or uncoupled coils forming directly coupled primary and secondary coils or loops
    • 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

Definitions

  • the invention includes a magnetic field-sensitive sensor, from whose output signal with speed-independent amplitude information about the distance, the rotational speed (speed) and the direction of rotation (direction of rotation) of a magnetic field can be obtained at the same time.
  • LBE Barkhausen effect
  • the magnetic reversal takes place in a time span of approximately 50 ⁇ s, which results in a cut-off frequency of f gr ⁇ 20 kHz for the LBE. Above f Gr , sensors previously used do not generate a technically usable signal.
  • sensors with LBE materials can be divided into two classes: sensors without a magnetic excitation field and sensors with a magnetic excitation field.
  • Puls without a magnetic excitation field are also referred to as pulse wire sensors (DE Pat. No. 3729949, DE 4107847, DE 3824075, DE 3406871).
  • the BME In sensors with a magnetic excitation field, the BME is constantly magnetized again by the magnetic field of an excitation coil with the excitation frequency f Err ⁇ , the condition for the occurrence of the LBE f Err ⁇ f Gr again having to be observed for the excitation frequency.
  • Sensors with a magnetic excitation field contain a sensor coil.
  • the voltage U s induced in this sensor coil has voltage peaks due to the magnetic reversal of the BME in each half-wave.
  • An external magnetic field can either amplify or weaken the voltage peaks in each half-wave of the sensor signal depending on the orientation of the external magnetic field.
  • the operating point of the sensors can be set by superimposing a constant magnetic field on an operating point coil (DE 3241018, DE 3718857, DE 4037052, DE 421358).
  • the function of the magnetic resonance sensor differs from other magnetic field-sensitive sensors, which also use an oscillating circuit (DE 8227446, DE 8316996, DE 8517733, DE 9010779, DE 9412765), through the use of a BME as the core of the sensor coil and the possibility of simultaneous speed as well as measuring the direction of rotation and distance of the magnetic field from the sensor.
  • an oscillating circuit DE 8227446, DE 8316996, DE 8517733, DE 9010779, DE 9412765
  • the aim of the invention is to develop a sensor whose operating frequency clearly exceeds the limit frequency f Gr of the magnetic sensors with BME as the core, which is shown in the prior art, and whose output signal simultaneously contains information about the distance, speed and direction of rotation of the magnetic field. Since the limit frequency f Gr of the LBE is determined by objective physical processes, a different physical principle must be used for the sensor function.
  • the object is achieved according to the invention by the magnetic resonance sensor and a method for detecting the position and change in position of objects interacting with magnetic fields (FIG. 1).
  • the resonator system (sensor) consists of
  • a bistable magnetic core (1) at least one excitation coil (3),
  • a means for generating a magnetic field consisting either of a permanent magnet and / or a coil,
  • a high-frequency resonant circuit made up of at least one sensor coil (5) and at least one capacitor (6).
  • the high-frequency generator (2) feeds an advantageously sinusoidal AC voltage of the constant ampute voltage U and the constant resonance frequency f Res of the high-frequency resonant circuit into the excitation coil (3). As long as an outside
  • the excitation coil induces via the bistable one magnetic core (1) in the sensor coil a periodic voltage of constant amplitude and the same frequency.
  • a periodic voltage of the resonance frequency f Res with constant amplitude U s is taken off as a sensor output voltage via the high-frequency resonant circuit. The amplitude of the
  • Sensor output voltage is determined by the amplitude U Err of the high-frequency generator (2) and the operating point of the sensor.
  • This operating point can be determined by at least one of the following means: a) permanent magnet,
  • Peak amplitude of the pulse U p is independent of the change over time
  • the pulse width is proportional to the length of time that the value H Schw is exceeded or undershot.
  • the sensor function is based on the following physical processes:
  • the magnetic domains of the LBE materials are also exposed to the force of the excitation magnetic field with high-frequency external excitation magnetic fields with f Err > f Gr .
  • the domains cannot change their orientation completely, but start to oscillate at the frequency f Err due to their preferred orientation. This collective effect can still be observed at f Err > 1 MHz.
  • the vibration behavior is significantly worse because the domains interfere with each other.
  • the collective oscillation of the magnetic domains in LBE materials leads to an oscillation of the magnetic flux density B with the frequency f Err .
  • the resonance the changes in the signal of the sensor coil are amplified in such a way that they can be evaluated by measurement.
  • the sensor If no external magnetic field acts on the sensor, it delivers a periodic output signal of constant basic amplitude U G with the resonance frequency f Res of the resonant circuit integrated in the sensor.
  • the sensor When exposed to a magnetic field with the field strength H at the sensor location, where H must be greater than a threshold field strength H Scnw that is characteristic of the sensor core , the sensor delivers a pulse signal with exponential edges and the peak amplitude U P for the duration of the exposure to the magnetic field.
  • the speed can be determined from the width of the envelope of the pulse signal, and the distance from the sensor to the center of the magnetic field can be determined from the peak amplitude.
  • the magnetic resonance sensor can be used as a sensor for non-contact speed, direction of rotation and distance measurements as well as for the simultaneous measurement of speed, direction of rotation and distance. Distance, direction of rotation and speed measurements can be carried out using non-magnetic materials with a total thickness of over 5 cm. The total thickness of the non-magnetic materials can be made up of several components (e.g. aluminum housing and oil bath). Speeds up to n ⁇ 10 4 / min common in machine and engine construction can be measured.
  • the sensor can also be used under harsh environmental conditions (eg contamination of the surfaces) where optical sensors are no longer functional. Appropriate constructive measures in the design of the control magnetic field also allow angles of rotation to be measured.
  • the senor compared to pulse wire sensors are the significantly higher working frequency of the sensor, which is not limited by the LBE.
  • the sensor does not require a reset magnetic field.
  • its response time to an external magnetic field can be significantly lower than that for the
  • the invention is also characterized by the higher one
  • the width of the peak signal is inversely proportional to the speed. Therefore, the instantaneous speed can be determined from the width of the peak signal, while in the case of sensors based on the LBE, the speed can only be measured from the chronological sequence of two peaks, which corresponds to an averaging. Best way to carry out the invention
  • Figure 1 shows the circuit diagram of the arrangement according to the invention.
  • the magnetic resonance sensor consists of an excitation coil, a sensor coil and a common core that contains a mechanically fixed BME.
  • the excitation and sensor coils are arranged on the common core so that the excitation coil induces a signal in the sensor coil with a basic amplitude of approximately 3V - 5V.
  • the working point of the sensor can be determined by a working point coil also arranged on the common core, but the sensor can also function without an working point coil.
  • the inductance L s of the sensor coil is determined by the coil structure.
  • a possible design variant of the sensor coil is a cylindrical coil with 1000 windings of a copper wire with 0.1 mm diameter for
  • the inductance of the sensor coil should be between 1mH and 10 mH.
  • the capacitance of the capacitor in the resonant circuit depends on the desired resonant frequency f Res of the sensor and is based on the resonant circuit formula by W.
  • the design of the excitation coil depends on the desired output voltage of the sensor. This is determined by the turns ratio n Err / n s of the excitation coil and the sensor coil.
  • the sinusoidal excitation voltage U Err with the excitation frequency f Err is generated by a high-frequency generator.
  • the time-constant amplitude of the excitation voltage should be in the range 5V -12 V.
  • the sensor output signal must be processed electronically. Demodulation, peak detection and the evaluation of one or more threshold values are possible.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Geophysics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
  • Measuring Magnetic Variables (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

L'invention concerne un détecteur sensible à un champ magnétique, à partir duquel des signaux de sortie peuvent être obtenus pour fournir simultanément des informations relatives à la distance, à la vitesse de rotation (nombre de tours-minute) et au sens de rotation d'un champ magnétique. Le champ magnétique peut être produit par un aimant permanent ou/et par action d'un courant électrique. L'invention a pour but de développer un détecteur, dont la fréquence de fonctionnement dépasse notablement la fréquence limite fGr que l'on relève, dans l'état de la technique, pour des détecteurs magnétiques à éléments magnétiques bistables (BME) comme noyau, et dont le signal de sortie renferme simultanément des informations relatives à la distance, à la vitesse de rotation et au sens de rotation d'un champ magnétique. Etant donné que la fréquence limite fGr du grand effet de Barkhausen (LBE) est déterminée par des processus physiques objectifs, il y a lieu d'utiliser, pour la fonction de détecteur selon l'invention, un autre principe physique. Le détecteur à résonance magnétique se différencie, dans sa fonction, des autres détecteurs sensibles au champ magnétique utilisant également un circuit oscillant, par le fait qu'il utilise un BME comme noyau de la bobine du détecteur et qu'il offre la possibilité de mesurer simultanément la vitesse de rotation, la distance et le sens de rotation.
EP96946119A 1996-12-27 1996-12-27 Detecteur a resonance magnetique Withdrawn EP1007909A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/DE1996/002513 WO1998029712A1 (fr) 1996-12-27 1996-12-27 Detecteur a resonance magnetique

Publications (1)

Publication Number Publication Date
EP1007909A1 true EP1007909A1 (fr) 2000-06-14

Family

ID=6918440

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96946119A Withdrawn EP1007909A1 (fr) 1996-12-27 1996-12-27 Detecteur a resonance magnetique

Country Status (4)

Country Link
US (1) US6304075B1 (fr)
EP (1) EP1007909A1 (fr)
JP (1) JP2001527641A (fr)
WO (1) WO1998029712A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10259223B3 (de) * 2002-11-20 2004-02-12 Mehnert, Walter, Dr. Positionsdetektor
US10634741B2 (en) 2009-12-04 2020-04-28 Endomagnetics Ltd. Magnetic probe apparatus
US9427186B2 (en) * 2009-12-04 2016-08-30 Endomagnetics Ltd. Magnetic probe apparatus
JP6351639B2 (ja) 2013-03-11 2018-07-04 エンドマグネティクス リミテッド リンパ節検出のための低浸透圧溶液
US9239314B2 (en) 2013-03-13 2016-01-19 Endomagnetics Ltd. Magnetic detector
WO2014140566A1 (fr) * 2013-03-13 2014-09-18 Endomagnetics Ltd. Détecteur magnétique
US9234877B2 (en) 2013-03-13 2016-01-12 Endomagnetics Ltd. Magnetic detector
EP3302338B1 (fr) 2015-06-04 2020-09-30 Endomagnetics Ltd. Matériaux et formes de marqueur pour localisation à marqueur magnétique

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2237203A1 (en) * 1973-07-13 1975-02-07 Mishima Kosan Co Ltd Detection and measurement of weak magnetic fields - involves detecting phase characteristics of voltage at detector
US4236093A (en) * 1978-05-18 1980-11-25 General Signal Corporation Speed insensitive wheel detector
JPS57173716A (en) * 1981-04-20 1982-10-26 Toshiba Corp Position detecting system
JPH03255380A (ja) * 1990-03-05 1991-11-14 Aichi Steel Works Ltd 透磁率測定装置
WO1995024571A1 (fr) 1994-03-07 1995-09-14 Klaus Michel Dispositif de surveillance et de commande pour systemes convertisseurs d'energie a commande magnetique
DE9412381U1 (de) 1994-08-01 1994-09-22 Siemens AG, 80333 München Magnetischer Näherungsdetektor
DE19523373C2 (de) 1995-06-29 1999-08-26 Hochschule Fuer Technik Magnetischer Resonanzsensor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9829712A1 *

Also Published As

Publication number Publication date
JP2001527641A (ja) 2001-12-25
WO1998029712A1 (fr) 1998-07-09
US6304075B1 (en) 2001-10-16

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