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
  • G01D5/142—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 using Hall-effect devices
  • G01D5/145—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 using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields

Definitions

• the present invention relates to the field of angular position detection of a rotating element with respect to a non-rotating element.
• the present invention relates to the field of rotary systems in which it is desirable to know the absolute angular position of a rotor with respect to a static element.
• JP.2000-241197 discloses a three-sensor rotation detection device mounted close to each other.
• JP 8-54205, JP 6-58770 and JP 2000-209889 disclose a three-sensor rotation detection device.
• the document FR 2 599 794 relates to a bearing with magnetic information sensors with a ring with a large number of poles.
• US 6,288,533 discloses a method for determining the rotational position of a rotor carrying a magnetic source creating a magnetic field without rotational symmetry.
• the detection means comprise two pairs of detectors, the detectors of each pair being sensitive to the substantially parallel components of the magnetic field.
• the present invention aims to overcome the disadvantages of the devices mentioned above.
• the aim of the present invention is to provide a simple detection system that is not very sensitive to variations in the amplitude of the magnetic signal and to shifts due to mounting or voltage variations.
• a system for detecting the angular position of a rotating element with respect to a non-rotating element comprises an annular encoder provided with a number P of poles greater than or equal to 2 intended to be fixed on one of the rotating elements or not turning and a number
• N of sensors with N odd and greater than or equal to 3, adapted to receive a signal from the encoder and mounted on the other elements not rotating or rotating opposite said rotating or non-rotating element angularly distributed and at least one module subtraction device capable of processing at least two output signals of the sensors to generate a differential signal.
• the system can be tricaptor or hexacapteur.
• the encoder may comprise two poles.
• the encoder can be bipolar with poles of 180 °.
• N is equal to 3, 5 or 7.
• the subtraction module comprises a digitizing circuit of the analog information and an integrated circuit for calculating the output voltage.
• the subtraction module comprises an analog circuit for calculating the output voltage.
• the system includes a bipolar annular encoder for attachment to the rotating member, three circumferentially uniformly distributed magnetic field sensors intended to be fixed on the non-rotating element facing the encoder, and the subtraction module receiving an output signal from each sensor, said signal being representative of the magnetic field measured by the sensor, and outputting a differential signal representative of the angular position ⁇ of the rotating member relative to the non-rotating member.
• the output signal of the calculation module comprises a sine signal and a cosine signal of the angular position ⁇ of the rotating element relative to the non-rotating element.
• the subtraction module comprises amplifiers mounted in summator and / or subtracter.
• a first amplifier is subtractor-mounted to provide a first output signal
• a second amplifier is summator-inverter-mounted
• a third amplifier is summator-mounted to provide a second output signal, the output of the second amplifier being connected to an input of the third amplifier.
• the subassembly comprising the amplifiers can be realized economically by an analog circuit.
• the subtraction module comprises a sensor filter, three amplifiers mounted at the output of the filters and an interpolator mounted at the output of the amplifiers.
• the interpolator can be of analog or digital type.
• the calculation module in operation provides a first output signal equal to (V3 / 2) (B 2 - B 3 ) AA and a second output signal equal to (B 1 - (B 2 - B 3 ) / 2) / A, A being a constant.
• the subtraction module comprises an interpolator receiving as input the sine and cosine of said angular position and outputting said angular position ⁇ .
• the sensors are distributed non-periodically to optimize the errors related to the shape emitted by the annular emitter ring. In one embodiment, the sensors are arranged in the same housing.
• the system comprises a mechanical ratio reduction gearbox.
• the system includes a mechanical counter incremented one notch each turn.
• the system comprises three sensors arranged on an angular sector of 2 ⁇ / 3, and a bipolar encoder.
• the system comprises three sensors arranged on an angular sector of ⁇ / 3 and a quadrupole encoder.
• the system comprises three sensors arranged on an angular sector of 4 ⁇ / 9 and a haphapolar encoder. In one embodiment, the system comprises three sensors arranged on an angular sector of ⁇ / 6 and an octopolar encoder.
• a bearing may comprise two rings, a row of rolling elements arranged between the rings and a system of detection, said system providing the angular position of one ring relative to the other ring.
• a rotating machine such as an electric motor, may comprise a rotor, a stator and a detection system, said system providing the angular position of the rotor relative to the stator.
• the position detection is performed reliably and is not very sensitive to external disturbances.
• FIG 1 is a schematic cross-sectional view of a detection system
• FIG 2 is a curve of evolution of the magnetic field seen by a sensor as a function of the angle
• FIG. 3 is a schematic view of an electronic processing circuit
• FIG. 4 is a schematic view in axial section of an electric motor
• FIG. 5 is a diagrammatic cross-sectional view of a bearing
• FIG. 6 is a schematic view from above of a detection assembly
• FIG. 7 is a view from above of a tower counting system for the assembly of FIG. 6;
• FIG 8 is a sectional view along VIII-VIII of Figure 7;
• FIG 9 is a schematic view of an electronic processing circuit
• FIG. 10 is a schematic view from above of a detection system
• FIG 1 1 is a schematic top view of a detection system
• FIG 12 is a schematic sectional view of the detection system of Figure 1 1;
• FIG. 13 is a schematic view from above of a detection system
• FIG. 14 is a diagrammatic sectional view of the detection system of FIG. 13;
• FIG. 15 is a diagrammatic sectional view of a detection system
• FIG. 16 is a schematic view of a detection system
• FIG 17 is a schematic top view of a detection system.
• the detection system comprises three magnetic field sensors 1, 2, 3, for example Hall effect probes, uniformly distributed circumferentially around a coding ring 4.
• Encoder ring 4 comprises a north pole occupying an angular sector of 180 ° and a south pole occupying an angular sector of 180 ° and is rotatable relative to the sensors 1 to 3.
• the precision obtained in the case of a magnetic signal distorted by relative to a sinusoidal signal, for example a triangular magnetic signal, may be 1, 2 °.
• Five sensors can be provided for an accuracy of 0.3 °.
• An odd number of sensors allows a better recomposition of the signal, in particular by an improved suppression of harmonics, in particular harmonics due to a deformation of the signal which tends to become more triangular.
• the encoder ring can be made by magnetization of a magnetic alloy or a plasto-ferrite or an elasto-ferrite.
• the magnetic field B has a constant modulus B max with close external disturbances and the orientation of the magnetic field depends on that of the encoder 4.
• the sensor 1 detects the field B ⁇ of value B max cos ⁇ , ⁇ being the angle between the position angular sensor 1 relative to the center of rotation of the encoder 4 and the field B.
• ⁇ is the angle between two lines both passing through the center of rotation of the encoder 4, one passing through the sensor 1, and the other passing through the center of the north pole of the encoder 4.
• the field Bi evolves as illustrated in FIG. 2.
• the field Bi is equal to B max cos ( ⁇ + 120 °) and the field B 3 is equal to B max cos ( ⁇ + 240 °).
• Bj / B max cos (2 ⁇ (il) / 3 + ⁇ ).
• the detection system comprises an electronic circuit 5 for formatting the results of the measurement.
• the output of each sensor 1 to 3 is connected to a filter 6 to 8, to provide a detected magnetic field signal.
• the electronic circuit 5 comprises, in addition to the filters 6 to 8, two amplifiers 9 and 10.
• the amplifier 9 receives on its inverting input the signal B 3 coming from the filter 8 of the sensor 3 via a resistor 12.
• the resistor 12 comprises in series a fixed resistor 12a and a potentiometer 12b on the one hand, and in parallel with the potentiometer 12b, a fixed resistor 12c on the other hand.
• a resistor 11 is mounted between the inverting input and the output of the amplifier 9.
• the amplifier 9 receives on its non-inverting input, the signal B 2 from the filter 7 of the sensor 2 via a resistor 13.
• a resistor 14 is arranged, on the one hand, between the point common to the non-inverting input of the amplifier 9 and the resistor 13 and, on the other hand, a circuit ground.
• the 15 is arranged, on the one hand, between the point common to the non-inverting input of the amplifier 9 and the resistor 13 and, on the other hand, to a power supply of the circuit, for example + 5v.
• the amplifier 9 outputs a voltage equal to the sine of the angle ⁇ to a constant ready.
• the amplifier 9 thus realizes the difference between the field B 2 and the field B 3 .
• the amplifier 10 comprises a non-inverting input Bi signal from the filter 6 of the sensor 1 through a resistor 17.
• the resistor 17 includes in series a resistor fixed 17a and a potentiometer 17b on the one hand, and in parallel with the potentiometer 17b, a fixed resistor 17c on the other hand.
• a resistor 11 is mounted between the inverting input and the output of the amplifier 9.
• a resistor 18 is disposed, on the one hand, between the point common to the non-inverting input of the amplifier 10 and the resistor 17 and, on the other hand, to a circuit ground.
• a resistor 19 is arranged, on the one hand, between the point common to the non-inverting input of the amplifier 10 and the resistor 17 and, on the other hand, to a supply of the circuit, for example + 5v.
• the amplifier 10 comprises an inverting input receiving, on the one hand, the signal B 2 via a resistor 20 and, on the other hand, the signal B 3 via a resistor 21.
• Resistor 21 comprises in series a fixed resistor 21a and a potentiometer 21b on the one hand, and in parallel with the potentiometer 21b, a fixed resistor 21c on the other hand.
• a resistor 22 is mounted between the inverting input and the output of the amplifier 9.
• the amplifier 10 performs the addition of the signal Bi and the inverse of the sum of the signals B 2 and B 3 .
• the output signal of the amplifier 10 is equal to the cosine of the angle ⁇ at a constant ready.
• the sinus ⁇ and cosine ⁇ respectively output signals of the amplifier 9 and of the amplifier 10, are sent to an interpolator 23 configured to calculate tg ⁇ , that is to say the division of the sine by the cosine and to apply an arc-tangent function to provide the angle ⁇ at the output.
• the angle ⁇ is thus calculated reliably while being insensitive to variations of the modulus B max of the magnetic field, as well as initial offsets, including mechanical offsets.
• the differential detection system may be applied to an electric motor illustrated in FIG. 4 and comprising a stator 23, and a rotor 24 mounted on a shaft 25 supported by bearings 26 and 27.
• the circuit 5 is mounted in the immediate vicinity of the sensor 1.
• the sensors and the processing circuit 5 are supported by the stator 23, while the encoder 4 is supported by the rotor 24.
• the detection system is mounted in a rolling bearing referenced 28 as a whole.
• the rolling bearing 28 comprises an outer ring 29 and an inner ring 30 supporting the encoder 4.
• the inner ring 29 supports the sensors 1 to 3 and the processing circuit 5.
• a device for differential position detection of a rotating element with respect to a non-rotating element may comprise a bipolar encoder intended to be fixed on the rotating element, three, five or seven magnetic field sensors. circumferentially regularly distributed, with an air gap with respect to the encoder and intended to be fixed on the non-rotating element, and a calculation circuit receiving an output signal of each sensor, said signal being representative of the magnetic field measured by the sensor.
• the calculation module is configured to output a signal representative of the angular position ⁇ of the rotating element relative to the non-rotating element.
• the calculation module may comprise a subset consisting of three amplifiers associated with resistors.
• the detection system comprises a small diameter gear 3 1 linked to a rotating element, not shown, the position of which is desired to be known, a double gear provided with a large-diameter toothing. 32 meshing with the small diameter gear 31 and a small diameter toothing 33, and a large diameter gear 34 meshing with the small diameter toothing 33 of the double gear.
• the large-diameter gear 34 comprises a spur 35 offset axially with respect to the gearing. and provided to cooperate with a gear wheel 36 axially offset from the large diameter gear 34.
• the gear wheel 36 is driven intermittently at each pass of the gear. ergot 35 nearby.
• Each angular displacement of the toothed wheel 36 corresponds to one turn of the large-diameter gear 34, in one direction or the other.
• the toothed wheel 36 is provided with an angular displacement sensor 37 which can be low-resolution economic type.
• the electronic processing circuit 38 comprises an analog digital converter 39 receiving as input the output signals of the sensors 1 to 3, a calculation module 40 comprising an input connected to the output of the converter 39, in particular configured to divide, for example, the signal sin ⁇ by the signal cos ⁇ to obtain at the output tan ⁇ , a calculation module 41 comprising an input connected to the output of the calculation module 40, notably configured to perform the tangent arc operation and obtaining the angle of exit ⁇ , and a shaping module 42 receiving as input the angle ⁇ and applying shaping, for example by pulse width modulation or by digital-to-analog conversion.
• the electronic processing circuit 38 thus provides digital processing which is desired in certain applications.
• the detection system comprises three sensors 1 to 3 arranged with an axial gap with respect to the bipolar encoder 4.
• the radial size is defined by the encoder 4 and is reduced with respect to the radial size of the system illustrated in FIG. 1.
• the sensors 1 to 3 are arranged radially between the two circles delimiting the encoder 4.
• the detection system comprises three sensors 1 to 3 arranged with an axial gap with respect to the encoder 43 and three permanent magnets 44,
• the encoder 43 comprises a flat plate of non-magnetic material, for example non-ferrous, of elliptical periphery and pierced with an elliptical opening whose axis formed by the foci is perpendicular to the axis formed by the foci of the peripheral ellipse for forming a bulge 47 relatively broad radially.
• the periphery of the encoder is centered on the axis of rotation of the encoder 43.
• the magnets 44, 45 and 46 are arranged on the side of the encoder 43 opposite to the sensors 1 to 3 and facing them. In other words, an axial air gap is provided between the magnets 44, 45 and 46 and the sensors 1 to 3. The axial air gap is sufficient to allow the encoder 43 to come between the magnets 44, 45 and 46 and the sensors 1 to 3.
• the bulge 47 of the encoder 43 is situated between the magnet 44 and the sensor 1, which strongly weakens the magnetic field perceived by the sensor.
• the encoder 43 is absent between the magnet 45 and the sensor 2 and between the magnet 46 and the sensor 3.
• the sensors 1 to 3 therefore provide signals similar to those provided in the previous embodiments.
• the embodiment illustrated in FIGS. 13 and 14 is similar to that of FIGS. 11 and 12, except that the magnets 44 to 46 and the sensors 1 to 3 are arranged on the same side of the encoder 43.
• the encoder 43 is then able to modify the magnetic field perceived by the sensors 1 to 3 according to its angular position.
• the embodiment illustrated in FIG. 15 is similar to that of FIGS. 13 and 14, except that the encoder 48 is inclined with respect to its axis of rotation.
• the encoder 48 comprises a flat plate of magnetic material, for example ferrous, circular periphery and pierced with a circular opening concentric to the periphery. During the rotation of the encoder 48, the distance between the encoder 48 and the sensors 1 to 3 varies sinusoidally. The encoder 48 modifies the magnetic field perceived by the sensors 1 to 3 according to the angular position of said encoder 48.
• the embodiment illustrated in FIG. 16 is similar to that of FIG. 15, except that the encoder 49 comprises an annular bipolar ring 50, for example based on magnetized plastoferrite.
• the encoder 49 inclined with respect to its axis of rotation, moves closer and cyclically away from each sensor 1 to 3 and generates a magnetic field 51 whose perception by each sensor 1 to 3 depends on the distance separating them and therefore of the angular position of the encoder 49.
• the encoder 52 comprises an annular bipolar ring with radial magnetization.
• one of the poles 53 is formed on the bore of the encoder and the other pole 54 on the periphery.
• the center 55 of the encoder 52 is shifted radially with respect to the axis of rotation 56.
• a sensor disposed with a radial air gap thus sees a north pole or a south pole as a function of the angular position of the encoder 51.
• the output signal of the sensors 1 to 3 is therefore representative of the angular position of the encoder 51.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)

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• 2006
  • 2006-01-06 FR FR0600120A patent/FR2896036B1/fr not_active Expired - Fee Related
• 2007
  • 2007-01-03 EP EP07712628A patent/EP1969319A2/fr not_active Withdrawn
  • 2007-01-03 WO PCT/FR2007/000001 patent/WO2007077389A2/fr active Application Filing
  • 2007-01-03 CN CNA2007800082739A patent/CN101400971A/zh active Pending
  • 2007-01-03 JP JP2008549038A patent/JP2009522567A/ja active Pending
  • 2007-07-03 US US12/087,425 patent/US20090219016A1/en not_active Abandoned

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