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
  • G01D5/244—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 characteristics of pulses or pulse trains; generating pulses or pulse trains
  • G01D5/245—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 characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/30—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes
• • 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
• • 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
  • G01D5/244—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 characteristics of pulses or pulse trains; generating pulses or pulse trains
  • G01D5/245—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 characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
  • G01D5/2454—Encoders incorporating incremental and absolute signals
  • G01D5/2455—Encoders incorporating incremental and absolute signals with incremental and absolute tracks on the same encoder
  • G01D5/2457—Incremental encoders having reference marks
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R33/00—Arrangements or instruments for measuring magnetic variables
  • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
  • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
  • G01R33/09—Magnetoresistive devices
  • G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors

Definitions

• Multipolar encoder for position sensors and detection device comprising such an encoder associated with at least one position sensor
• the present invention relates to the technical field of the detection of movements and positions of elements within mechanical systems. It particularly relates to the field of magnetic detection devices comprising an encoder element moving in proximity to a sensor cell or sensor and adapted to detect the position and / or speed of a moving target in the general sense.
• the object of the invention relates more particularly to the production of a magnetic encoder equipped with a series of north poles and of south poles mounted alternately to serve as a magnetized target for a GMR type detection cell (Giant Magneto- Resistance) differential.
• the object of the invention finds a particularly advantageous application in the automotive field where this sensor can be used, for example, in the context of injection functions.
• a sensor capable of providing information corresponding to the position of the moving target.
• a sensor cooperates traditionally with a moving target made for example of a soft magnetic material and having at least one, and generally, a series of teeth separated by recesses.
• a sensor also comprises a permanent magnet defining an air gap with the moving target.
• a sensor sensitive to the direction and the intensity of a magnetic induction. The displacement of the moving target causes, for each passage of a tooth in front of the probe, a variation of the magnetic induction crossing the probe which thus delivers an electrical signal as a function of the direction and amplitude of the magnetic induction.
• This sensitive probe is associated in particular with a hysteresis level comparator whose output takes a first logic state when the electrical signal delivered by the probe is greater than a predetermined threshold and a second logic state when the electrical signal is below a predetermined threshold.
• the disadvantage of such a sensor is its sensitivity to the variation of the parameters such as the temperature and the gap between the target and the sensor.
• a position or speed sensor device comprising a magnetic encoder passing in front of a detection cell.
• Such an encoder is constituted by a multipole magnetic ring provided on its circumference with north poles and alternating south poles.
• the disadvantage of such a sensor is its high sensitivity to the variation of the gap between the measuring cell and the encoder.
• Magnetic encoders including a so-called singular peripheral magnetization or marking zone are also known. This singular zone traditionally consists of a magnetic pole of greater angular width than the other poles of the encoder.
• This larger magnetization pole provides a variation in the period and amplitude of the output signal of the detection cell serving as a switching or reference signal to determine the rotational position of the element on which the encoder is fixed.
• Such encoders have the same disadvantage of sensitivity to the gap variation as the aforementioned encoders, and a high sensitivity to noise generated by the mechanical system in which the encoder and the position sensor are integrated.
• EP 0 611 952 A1 Another solution has been proposed in EP 0 611 952 A1 and which consists in providing a magnetic encoder comprising a singular zone comprising two north and south poles respectively strongly magnetized and separated from each other by an area with little or no magnetism.
• an encoder always provides an output signal whose switching area is extended, which therefore alters the accuracy of the detection device.
• an encoder comprising a zone with little or no magnetism in the marking zone tends to provide an imbalance between the two magnetic poles of the marking zone and the poles outside this zone, which prevents stability of the electrical front in the middle. of the zone and a stability of the periods on the range of gap.
• the object of the invention is therefore to overcome the drawbacks of the state of the art by proposing an encoder for position and / or velocity sensor, being insensitive to the variation of gap while being able to provide a useful signal with good measurement accuracy.
• the present invention first proposes a coder for a position sensor, of the type comprising a multipolar magnetic ring provided, on its circumference, poles with polarities of opposite signs, arranged alternately and being intended for scroll past a measuring cell delivering a differential periodic signal corresponding to the change in the intensity of the magnetic field delivered by the poles.
• This encoder comprises, in known manner, at least one marking zone having an angular width greater than the angular width of each of the alternating poles situated outside this zone on the circumference of the ring.
• the marking zone of the encoder of the invention comprises two contiguous singular poles having polarities of opposite signs arranged in the continuity of alternating poles of the ring and whose angular width is greater than that of the poles located out of the marking zone, the magnetization within the singular poles gradually evolving continuously between the two ends of the marking zone.
• the junction between the two singular poles is located in the middle of the angular width covered by the marking zone.
• the gradual magnetization of the singular poles follows an increasing or decreasing variation, which can be at substantially linear choice or follow a curve.
• the magnetic poles situated on either side of the marking zone also advantageously have a variable angular width which is smaller than that of the singular poles in the marking zone. More particularly, the angular width of the marking zone is between 15 and 20 ° and the angular width of the magnetized poles outside the marking zone is between 2 and 8 °.
• the present invention also provides in accordance with a second object thereof, a device for detecting the position of a movable member or member, in particular in a rotational movement, characterized in that it comprises at least one encoder such as as defined above, integral with said movable member and at least one measuring cell delivering a periodic differential electric signal corresponding to the change in the intensity of the magnetic field generated by the poles of said encoder.
• the measuring cell of the detection device of the invention is chosen to be a GMR type cell (Giant Magneto Resistance).
• the invention also relates to a method for detecting the position of a moving member driven by a rotational movement, wherein said mobile is equipped with an encoder as previously described and the variation of magnetic field generated by the poles of said encoder via a measuring cell delivering a signal differential current whose intensity varies in accordance with the variation of the magnetic field generated by the poles of the encoder according to the movement and the position of the moving body, the measuring cell being advantageously a GMR (Giant Magneto Resistance) type cell.
• GMR Gate Magneto Resistance
• FIG. 1 is a schematic plan view showing an exemplary embodiment of a position detection device according to the invention.
• FIG. 2 is a view, taken in a plane, of an exemplary embodiment of an encoder according to the invention.
• - Fig. 3 illustrates the evolution of the differential magnetic signal obtained during the running of an encoder according to the invention in front of a GMR detection cell as well as the digital signal obtained from the differential output electrical signal of the cell.
• Fig. 1 shows an exemplary embodiment of a position detection device 1 comprising a magnetic encoder 2 mounted for scrolling in front of at least one sensor or magnetic position sensor 3.
• the encoder 2 is constituted in the form of a multipolar magnetic ring , driven in rotation about its center, along an axis A and provided, on its circumference, with north poles N and south poles S alternating, having a preferably radial magnetization.
• the encoder 2 consists of a ring forming a support on which is adhered a ring, made of elastomer, charged with magnetized particles to form North N and South S poles.
• the measuring cell 3 delivers a periodic differential magnetic signal Sb corresponding to the evolution of the intensity of the magnetic field delivered by the poles passing in front of it.
• this detection cell 3 is a differential GMR cell (a giant magnetoresistive giant cell).
• the measuring cell 3 is connected to processing means, not shown but known per se, for obtaining a digital output signal Sd, which in this case is a square signal.
• the encoder 1 comprises a series of south poles S and north poles N, arranged to present a regular pitch spacing between two adjacent poles.
• the angular width I of each so-called regular pole is 3 °.
• the encoder 1 also comprises at least one singular or marking zone Pi having, between two adjacent regular poles Pa, a different spacing from the regular spacing pitch between the south poles S and north N outside this pole.
• the marking area Pi has an angular width Li of at least 18 ° and comprises, in accordance with the invention, a singular pole north Ni and a singular pole south Si adjacent one of the other and arranged in the continuity of alternating poles on the periphery of the coder I.
• the singular pole Ni North is interposed between the adjacent regular pole Pa south and the south singular pole Si which is adjacent to the regular pole North Pa. The singular poles Ni and Si are therefore joined.
• Each of the singular poles Ni, Si present in comparison with the other regular poles North N and south S of the encoder a much greater angular width, and preferably as shown, an angular width Ii approximately three times greater than that of the north and south poles regular N , S, that is to say a width Ii substantially equal to 9 °.
• the angular width Li of the marking zone Pi is between 15 and 20 ° and the angular width I of the regular magnetized poles outside the marking zone is between 2 and 8 °.
• the angular width Li of the marking area Pi is between 15 and 40 ° and the angular width I of the regular magnetized poles outside the marking zone is between 2 and 15. °.
• the marking area Pi of the encoder of the invention makes it possible to obtain a differential magnetic signal Sbi in this zone, which, unlike the signals traditionally obtained with the coders of the prior art, has a significant slope which passes through 0 in a single point, exactly at the junction between the two poles Ni and Si of the marking area Pi.
• each pole Ni, Si of the marking area Pi has an identical angular width Ii substantially equal to 9 °.
• measurements of corrections of the angular width of the north poles N and south S adajcents of the Pi marking area are implemented.
• the poles Ni, Si of the marking zone Pi have, according to the invention, a gradual magnetization between the ends of the marking zone Pi, such that the magnetic signal Gross, obtained by the passage of the poles Ni, Si in front of the measuring cell 3, varies symmetrically. In other words, the magnetization of the singular poles Ni, Si decreases or increases constantly from one end to the other of the marking area Pi.
• This gradual magnetization of the poles in the marking zone Pi is decreasing from the north pole Ni towards the south pole Si, or of course increasing from the south pole Si to the north pole Ni.
• the decay or growth of magnetization can follow any evolution, although a linear variation or a curve is nevertheless preferred.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2008
  • 2008-08-12 FR FR0855547A patent/FR2935045B1/fr active Active
• 2009
  • 2009-07-29 WO PCT/FR2009/051523 patent/WO2010018336A2/fr active Application Filing
  • 2009-07-29 US US13/057,163 patent/US20130187640A1/en not_active Abandoned
  • 2009-07-29 EP EP09740407A patent/EP2313746A2/de not_active Withdrawn
  • 2009-07-29 KR KR1020117005677A patent/KR20110055618A/ko not_active Application Discontinuation

Non-Patent Citations (1)

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