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 invention relates to a magnetic encoder ring of a rotor position sensor of an electrically commutated motor, which is rotatably connected to a rotor of the electrically commutated motor and which has a predetermined number of magnets with an alternating direction of magnetization.
• the rotor of the electric motor has only a limited number of pole pairs, from which a predetermined number of edges can be used for position determination.
• a magnetic encoder ring is non-rotatably connected to a rotor hollow shaft, for example, at a shaft end, which is why the magnetic encoder ring is mounted on-axis.
• the sensor which detects a spanned by the magnetic encoder ring magnetic field, for example, attached to the stator of the motor (off-axis) and thus does not rotate with the rotor shaft.
• switch halls there is the disadvantage with switch halls that the electric motor can not be positioned at will and that a resolution of the sensor signals is limited. Nevertheless, switch Halls widely used for commutation determination for block commutations. In linear sensors, the transmission of the analog signal is very sensitive to interference, with a signal transmission at a level at high speeds is too slow. High-resolution incremental encoders have the disadvantage that, after switching on the supply voltage, there is no assignment of the increments to the commutation times of the electrically commutated motor.
• the problem is in the determined by the number of poles and the ring diameter Pole length.
• the pole length is very limited, since the field profile is not optimally designed for the sensor. This creates a conflict between the ideal slope in the zero crossing of the output signal and the longest possible linear range.
• pole lengths of up to approximately 6 mm can be displayed as an evaluable sinewave. Due to the design, however, a pole length of 9 mm is required. In the zero crossing of the output signal in the known embodiments, no sufficient slope is ensured, so that a switching point of the switch Hall can not be determined accurately.
• the invention is thus based on the object of specifying a magnetic encoder ring of a rotor position sensor system of an electrically commutated motor in which the switching point of the sensor can be determined precisely on the basis of the smallest possible tolerance of the sensor hysteresis.
• each magnetic pole pair has at least one indentation.
• These indentations have the advantage that an approximately linear range of the magnetic flux density is set between two commutation steps and at the same time the slope of the output signal at the zero crossing of the sensor output signal does not become smaller than a predetermined application-dependent value, for example 2 mT / ° electrical. This ensures that at the zero crossing of the output signal from the sensor, a minimum slope is ensured, whereby the switching point of the sensor due to the sensor hysteresis has not too large tolerance.
• the indentation is formed by two adjacent magnetic poles of the magnetic pole pair, each magnetic pole having at least one partial indentation, which are brought together in the region of a preferably gap-free magnetic boundary.
• This embodiment allows the use of magnetic poles with greater pole length to, for example, 10 mm. Due to the size of the magnetic poles, the Generalinbuchtitch can be easily realized. By changing the geometry of the magnetic poles, the output characteristic of the sensor can be easily changed because the magnetic field is changed by this indentation.
• the indentation is trapezoidal.
• the trapezoidal shape of the indentation allows the flux characteristics of the magnetic field to become sufficiently linear around the zero point of the sensor signal. A too flat output signal is thereby reliably prevented, which is why a reliable evaluation of the output signal of the sensor is ensured.
• the indentation can also be formed approximately round, whereby likewise the flux density of the magnetic field is shaped so that a sufficiently evaluable linear course of the output signal of the sensor can be detected at the zero crossing.
• the geometry of the recesses to be selected can be varied and depends on the position of the sensor and the width of the magnets.
• the magnetic poles are arranged with the alternating direction of magnetization perpendicular to the magnetic encoder ring.
• the magnetic field can be influenced particularly well via the indentation, so that the evaluation device can accurately recognize the commutation point when the output signal of the sensor is evaluated.
• the magnetic poles having the alternating magnetization direction are arranged axially with respect to an axis of the rotor of the motor.
• the magnetic poles with the alternating direction of magnetization are arranged radially with respect to the axis of the rotor of the electrically commutated motor. This is particularly advantageous whenever the magnetic encoder ring is designed as a flat cylinder ring with magnets. Since the magnetic poles are attached to the front of the magnetic encoder ring, the evaluation of the output signal of the sensor, which is arranged off-axis improves.
• a development of the invention relates to an electrically commutated motor, comprising a rotor which is rotatably connected to a magnetic encoder ring, wherein on the magnetic encoder ring a predetermined number of magnetic poles is arranged with an alternating direction of magnetization, and a stator to which a sensor outside the axis of rotation of the Rotor is arranged.
• the magnetic encoder ring is formed according to one of the features of the present patent application.
• FIG. 1 a magnetic encoder ring fastened to a rotor
• FIG. 2 magnetic transmitter ring
• FIG. 3 section of the magnetic encoder ring according to FIG. 2 with optimized geometry of the magnetic poles
• FIG. 4 signal course with and without geometry optimization of the magnetic poles
• FIG. 5 Signal curve with geometry optimization of the magnetic poles. Identical features are identified by the same reference numerals.
• a rotor 1 is shown, which is designed as a hollow shaft.
• the rotor 1 of the commutated motor not shown further, has a magnetic encoder ring 2 designed as a hollow cylinder on a front side facing a sensor arranged on a stator and having a predetermined number of magnetic poles N, S which are arranged in an alternating manner.
• the magnetic poles N, S of the magnetic encoder ring 2 are arranged radially to the axis of the rotor 1.
• Rotor magnets 3 are fastened within the rotor 1 designed as a hollow shaft, the rotor magnets 3 having the same number of pole pairs N, S as the magnetic encoder ring 2.
• a pole pair N, S is formed by two magnetic poles N, S whose magnetization direction is in the opposite direction.
• the number of rotor magnets 3 is determined by the electrically commutated motor, whereby the number of magnetic poles N, S is determined on the magnetic encoder ring 2.
• a sensor system is to be understood as meaning a unit of sensor and evaluation device.
• Figure 2 shows the magnetic encoder ring 2 according to Figure 1 in a plan view.
• S On the magnetic encoder ring 2 extends between each magnetic pole N, S a recess 4, which constricts the magnetic poles N, S in their Magnetangrenzung 7.
• these indentations 4 are formed and limited only on the side of the magnetic encoder ring 2 facing the sensor system.
• Figure 3 shows a section through a magnetic pole pair of the magnetic encoder ring 2, wherein two adjacent magnetic poles N, S are shown. This section through the magnetic poles N, S is guided parallel to the axis of the rotor 1.
• the magnetization direction of the magnetic poles N and S is illustrated by the arrows 5 and 6, wherein the magnetic pole N forms a north pole, while the magnetic pole S forms a south pole.
• Each magnetic pole pair N, S is joined approximately gap-free in a magnetic boundary 7, wherein this magnetic limit 7 represents the zero crossing in the electrical output signal of the sensor.
• the indentation 4 is designed in the direction of the magnetization of the individual magnetic poles N, S and is formed by a first partial recess 8 of the magnetic pole N and a first partial recess 9 of the magnetic pole S.
• the merging of the two partial recesses 8 and 9 forms the indentation 4, wherein the partial recesses 8 and 9 are formed such that material is removed from the magnetic poles N and S at this point, without the magnetic poles N, S to separate.
• This flat indentation 4 on the top Area of the magnetic poles N, S has the consequence that the magnetic flux density changes at this position of the magnetic encoder ring 2.
• the partial recesses 8, 9 are formed in particular at the corner regions of the radial extension of the magnetic poles N, S. In order to form further indentations 4 in the region adjacent to magnetic poles N, S, both the magnetic pole N and the magnetic pole S have a further partial recess 10 or 1 1.
• FIG. 4 shows the signal curve of the axial magnetic flux density over the rotational angle P of the rotor 1 of the electrically commutated motor.
• the electrically commutated motor is driven with a block commutation, wherein the perpendicular lines at 60 °, 120 °, 180 °, 240 ° and 300 ° each represent a commutation point K.
• two Hall sensors detect a magnetic flux of a magnetic field which varies as a result of the magnetic transmitter ring 2 attached to the rotor 1.
• the curve H1 is detected by a first Hall sensor not shown in detail. Between magnetic encoder ring 2 and sensors there is a nominal decency of 1 mm.
• the curve H2 shows the output signal of a second Hall sensor.
• the geometry optimization the magnetic field is changed so that its Flux density, which is detected by the sensors in different positions of the magnetic encoder ring 2, in the region of the zero crossing of the output signal has approximately a slope of 45 °.
• a linear slope allows a highly accurate determination of the commutation point of the motor.
• the depth Ti and the dimensioning of the indentation 4 must also be specified. This must be done in close coordination with the sensors used and must be left to the expert, taking into account the individual technical case.
• Such magnetic encoder rings 2 with indentations 4 can by means of conventional Production process can be generated.
• the described magnetic encoder ring 2 is designed such that a largely linear region of the axial magnetic flux density between two Kommutleitersuzeen arises and at the same time the slope of the magnetic flux density at the zero crossing is not smaller than a predetermined application-dependent value, for example 2 mT / ° electrical.
• FIG. 5 shows an exemplary profile of the magnetic flux density over the angle of rotation of the rotor 1 with different distances between the magnetic encoder ring 2 and the sensor system.
• the dashed curve A shows a straight line with an application-specific minimum slope of the magnetic flux density of 2 mT / ° electrically in this case, while the dashed curve B indicates an application-specific desired slope, in this case, for example, 4 mT / ° electrically the magnetic flux density.
• the curve C shows the course of the sensor output signal without geometry optimization of the magnetic encoder ring 2, wherein the distance is 0.75 mm.
• the curve D represents a sensor output signal, which was recorded with uncorrected geometry of the magnetic poles N, S of the magnetic encoder ring 2 at a distance of 1, 25 mm.
• the magnetic poles N, S provided with a trapezoidal recess 4 with a depth Ti of 0.4 mm results in a curve, as shown in the curve E.
• this curve E can be compared with the curve C, in which no influence on the geometry of the magnetic poles N, S was made.
• the curve E around the zero point of 90 ° electrically has a slope which runs approximately linearly.
• Magnetic poles N, S with a trapezoid-like indentation 4 of a depth Ti of 0.4 mm were also used in the recording of the curve F, the curve F having a linear gradient which comes very close to the desired gradient of the curve B.
• the curve F thus corresponds to the desired geometry-influenced output signal of the Hall sender, in contrast to the curve D, which was recorded without geometry influence.

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

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• 2013
  • 2013-05-15 CN CN201380029570.7A patent/CN104335014B/zh not_active Expired - Fee Related
  • 2013-05-15 DE DE102013208986A patent/DE102013208986A1/de not_active Withdrawn
  • 2013-05-15 WO PCT/EP2013/060040 patent/WO2013186001A1/fr not_active Ceased
  • 2013-05-15 DE DE112013002888.3T patent/DE112013002888A5/de not_active Withdrawn

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