WO2019219599A1 - Apparatus and method for detecting angular position of rotary element - Google Patents

Apparatus and method for detecting angular position of rotary element Download PDF

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Publication number
WO2019219599A1
WO2019219599A1 PCT/EP2019/062197 EP2019062197W WO2019219599A1 WO 2019219599 A1 WO2019219599 A1 WO 2019219599A1 EP 2019062197 W EP2019062197 W EP 2019062197W WO 2019219599 A1 WO2019219599 A1 WO 2019219599A1
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WO
WIPO (PCT)
Prior art keywords
rotary element
detecting
angular position
halves
electric motor
Prior art date
Application number
PCT/EP2019/062197
Other languages
French (fr)
Inventor
Xiaoyun Zang
Alexander Boronka
Original Assignee
Robert Bosch 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 Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO2019219599A1 publication Critical patent/WO2019219599A1/en

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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
    • G01D5/26—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/347—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
    • G01D5/34776—Absolute encoders with analogue or digital scales
    • 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
    • G01D5/26—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • 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
    • G01D5/26—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/40—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 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light specially adapted for use with infrared light
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • H02P25/022—Synchronous motors
    • H02P25/024—Synchronous motors controlled by supply frequency
    • H02P25/026—Synchronous motors controlled by supply frequency thereby detecting the rotor position
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/14—Electronic commutators
    • H02P6/16—Circuit arrangements for detecting position
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2203/00—Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor
    • H02P2203/03—Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation

Definitions

  • the present invention relates to the detection of an angular position of a rotary element, in particular to an apparatus and method for detecting an angular position of a rotary element.
  • a giant magnetoresistance sensor generally requires a rotation shaft of the electric motor to be non-hollow, so that a magnet can be mounted to an end of the rotation shaft, to enable the giant magnetoresistance sensor to detect a magnetic field; in the case of a rotary transformer, a rotor diameter thereof often needs to be greater than a diameter of the electric motor rotation shaft, in order that the rotary transformer can be mounted. It has also been proposed that the angular position of the rotor be detected by arranging an LED lamp on the rotor; this method similarly needs a large space to mount the associated elements, and the level of precision is not high.
  • An object of the present invention is to provide an apparatus and method for detecting an angular position of a rotary element such that, based on the apparatus and method of the present invention, costs can be lowered.
  • Another object of the present invention is to provide an apparatus and method for detecting an angular position of a rotary element such that, based on the apparatus and method of the present invention, only a small space is needed to mount the apparatus for detecting an angular position of a rotary element.
  • Another object of the present invention is to provide an apparatus and method for detecting an angular position of a rotary element such that, based on the apparatus and method of the present invention, the precision of detection of the angular position of the rotary element can be significantly improved.
  • an apparatus for detecting an angular position of a rotary element comprising:
  • the detectable region comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner; a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element.
  • the two halves when opened out in a plane, form a rectangle shape, and the two halves are formed by separation along a diagonal of the rectangle.
  • the two halves are directly formed on the rotary element.
  • the two halves are disposed on a cylindrical shrink ring, and the shrink ring is mounted in a fixed manner on the rotary element.
  • the two halves are a pale-coloured half and a dark-coloured half differentiated by colour.
  • the pale-coloured half is a white half
  • the dark-coloured half is a black half.
  • the rotary element is a rotation shaft of an electric motor.
  • the electric motor is a permanent magnet synchronous electric motor, and a pattern formed by the two halves is disposed within a range of every 360° /N in a circumferential direction of the rotation shaft, wherein N is the number of pairs of magnetic poles disposed on a stator of the electric motor.
  • the detection element is an infrared sensor comprising an emitter and a receiver.
  • the apparatus for detecting an angular position of a rotary element further comprises a light blocking shroud covering the infrared sensor and having a slit.
  • the processing unit further comprises:
  • a power supply line receiving electrical energy from outside and used for supplying power to the detection element; a signal amplifier for amplifying an optoelectrical signal from the detection element; and
  • a signal processor for processing a signal amplified by the signal amplifier, wherein the processed signal is supplied to a microcontroller of the rotary element.
  • the power supply line, the signal amplifier and the signal processor are integrated as a printed circuit board.
  • a method for detecting an angular position of a rotary element comprising:
  • the detectable region comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner, and a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element; detecting the detectable region, to acquire the ratio of areas or lengths of regions, detected by the detection element, of the two halves; and processing a signal representing the ratio.
  • the processed signal is supplied to a microcontroller of the rotary element.
  • the angular position of the rotation shaft can be uniquely determined by the detection element detecting at least one pattern formed by two halves and disposed on the rotation shaft.
  • the apparatus for detecting an angular position of an electric motor rotation shaft has a simple structure, a low cost, and requires little mounting space.
  • Fig. 1 is a simplified schematic diagram, schematically showing an electric motor provided with an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention.
  • Fig. 2 is a three-dimensional schematic diagram of the shrink ring fitted to the rotation shaft of the electric motor in fig. 1.
  • Fig. 3 is a planar schematic diagram of a shrink ring body after opening out the shrink ring in fig. 2.
  • Fig. 4 is a schematic diagram showing the projection of detection light onto the opened-out shrink ring body.
  • Fig. 5 schematically shows a processing unit, for processing a signal from the detection element, of an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention.
  • Fig. 1 is a simplified schematic diagram, schematically showing an electric motor provided with an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention.
  • a housing of the electric motor has been partially omitted in fig. 1.
  • the electric motor 1 in fig. 1 is for example a permanent magnet synchronous electric motor, substantially comprising a stator 5 disposed in a housing 3, and a rotor 7 which is located in a central part of the stator 5 and capable of rotating relative to the stator 5.
  • the rotor 7 comprises a rotation shaft 9 and a rotor core mounted on the rotation shaft 9.
  • an apparatus 11 for detecting an angular position of an electric motor rotation shaft comprises a detectable region 13 disposed on the rotation shaft 9, a detection element 15 for detecting the detectable region, and a processing unit 17 for processing a signal from the detection element.
  • the detectable region 13 disposed on the rotation shaft 9 is a shrink ring 19 fixed to the rotation shaft 9.
  • the shrink ring 19 is a cylindrical sleeve.
  • a shrink ring body 19a should have the rectangular shape shown in fig. 3.
  • the shrink ring body 19a is designed as a pale-coloured half 21a and a dark-coloured half 21b, along a diagonal 19b of the shrink ring body 19a with the rectangular shape shown in fig. 3.
  • the pale-coloured half 21a is coated so as to be white
  • the dark-coloured half 21b is coated so as to be black.
  • the pale colour and the dark colour need not be restricted to white and black, as long as these two parts form regions which can be detected by the detection element in a differentiated manner.
  • the detection element 15 for detecting the detectable region may be any suitable sensor capable of recognizing a pattern formed by the mutually differentiated pale-coloured half 21a and dark-coloured half 21b on the shrink ring 19.
  • the detection element 15 for detecting the detectable region is an infrared sensor comprising an infrared emitter and an infrared receiver.
  • the detection element 15 for detecting the detectable region could also employ a suitable sensor other than an infrared sensor.
  • the detection element 15 for detecting the detectable region may be disposed on a support part 23 fixed to the housing 3 of the electric motor; the distance from the detection element 15 for detecting the detectable region to the shrink ring 19 fixed to the rotation shaft 9 of the electric motor is selected so that the detection element 15 for detecting the detectable region has optimal detection precision.
  • the detection element 15 for detecting the detectable region is covered by a light-blocking shroud 25, and the light-blocking shroud 25 has a slit such that only a narrow infrared light beam is projected onto the shrink ring 19.
  • Fig. 4 is a schematic diagram showing the projection of detection light onto the opened-out shrink ring body, and is intended to explain the operating principles of the apparatus for detecting an angular position of an electric motor rotation shaft according to the present invention.
  • the dotted-line box 27 in the figure represents an infrared light beam emitted by an emitter of the detection element 15 for detecting the detectable region and projected onto the shrink ring 19; the infrared light beam is received by a receiver of the detection element 15 for detecting the detectable region after reflection by the pattern formed by the pale- coloured half 21a and the dark-coloured half 21b on the shrink ring 19.
  • the ratio of a region area of the pale-coloured half 21a detected by the infrared light beam to a region area of the dark-coloured half 21b detected by the infrared light beam is uniquely determined; therefore, once the ratio of the region area of the pale-coloured half 21a detected by the infrared light beam to the region area of the dark- coloured half 21b detected by the infrared light beam has been acquired, the angular position of the electric motor rotation shaft at the corresponding moment can be learnt or tracked.
  • the “lengths” of the two halves detected should be the lengths of the detected regions of the two halves in a direction parallel to the electric motor rotation shaft.
  • one pale-coloured half 21a and one dark-coloured half 21b are arranged symmetrically along the entire circumference of the shrink ring 19, i. e. within a range of 360° in the circumferential direction; correspondingly, the stator of the electric motor is only provided with one pair of magnetic poles. If the stator of the electric motor is provided with two pairs of magnetic poles, one pale-coloured half 21a and one dark- coloured half 21b are arranged symmetrically along half a circumference of the shrink ring 19, i. e. within a range of every 180° in the circumferential direction.
  • one pale-coloured half 21a and one dark-coloured half 21b are arranged symmetrically along 1/N of the circumference of the shrink ring 19, i. e. within a range of every 360° /N in the circumferential direction.
  • a pattern formed by one pale-coloured half 21a and one corresponding dark-coloured half 21b respectively corresponds to a corresponding pair of magnetic poles of the stator of the electric motor.
  • Fig. 5 schematically shows a processing unit, for processing a signal from the detection element, of an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention.
  • the processing unit 17 for processing a signal from the detection element comprises a power supply line 25, which receives electrical energy from outside and is used for supplying power to the detection element 15 for detecting the detectable region.
  • the processing unit 17 for processing a signal from the detection element further comprises a signal amplifier 27 for amplifying an optoelectrical signal from the detection element 15 for detecting the detectable region, and a signal processor 29 for processing a signal amplified by the signal amplifier 27.
  • the signal processor 29 processes the optoelectrical signal by means of control software, and converts the optoelectrical signal into a differential signal receivable by a microcontroller of the electric motor.
  • the microcontroller of the electric motor controls a current or voltage applied to the stator of the electric motor according to the differential signal indicating rotation shaft angular position, and thereby controls the direction of a magnetic field generated by the stator of the electric motor.
  • the power supply line 25, signal amplifier 27 and signal processor 29 of the processing unit 17 for processing a signal from the detection element are all integrated as a printed circuit board.
  • the processing unit 17 for processing a signal from the detection element may be mounted on the housing of the electric motor independently of the detection element 15 for detecting the detectable region, and may also be integrated on a control panel of a control apparatus of the electric motor.
  • the pattern formed by the pale-coloured half 21a and the dark-coloured half 21b is arranged on the shrink ring 19, and the shrink ring 19 is then fixed to the rotation shaft 9 of the electric motor; however, it should be understood that the pattern formed by the pale-coloured half 21a and the dark-coloured half 21b may be arranged on the rotation shaft 9 of the electric motor directly.
  • the pattern formed by the pale- coloured half and the dark-coloured half, which are differentiated from each other by colour may also be replaced by a pattern formed by halves capable of being detected in a mutually differentiated manner by, for example, a smooth half and a rough half, or a protruding half and a depressed half, etc.
  • the pattern in the present invention is not limited to a pattern formed by colour.
  • the region formed by the two halves after being opened out is not restricted to being rectangular.
  • the angular position of the rotation shaft can be uniquely determined by the detection element detecting at least one pattern formed by two halves and disposed on the rotation shaft; not only can the measurement precision be significantly improved, but the apparatus for detecting an angular position of an electric motor rotation shaft has a simple structure, a low cost, and requires little mounting space.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)

Abstract

The present invention provides an apparatus and method for detecting an angular position of a rotary element. The apparatus for detecting an angular position of a rotary element comprises a detectable region disposed on the rotary element, a detection element for detecting the detectable region, and a processing unit for processing a signal from the detection element, characterized in that the detectable region comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner; a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element. According to the present invention, not only can the measurement precision be significantly improved, but the apparatus for detecting an angular position of an electric motor rotation shaft has a simple structure, a low cost, and requires little mounting space.

Description

Description
Apparatus and method for detecting angular position of rotary element
Technical field
The present invention relates to the detection of an angular position of a rotary element, in particular to an apparatus and method for detecting an angular position of a rotary element.
Background art
In electric motors such as permanent magnet synchronous electric motors, in order to drive the permanent magnet synchronous electric motor, it is necessary to detect the angular position of a rotor of the electric motor, in order to perform magnetic field directional control, i. e. determine the direction of the magnetic field which should be applied to a stator according to a magnetic field direction of a rotor permanent magnet in the course of rotation. In order to detect the angular position of the rotor of the electric motor, it is generally necessary to provide a position sensor such as a rotary transformer, a Hall sensor, a giant magnetoresistance sensor or an optical encoder, etc. These position sensors are not only expensive but also require the electric motor to have a specially designated space for their installation. For instance, a giant magnetoresistance sensor generally requires a rotation shaft of the electric motor to be non-hollow, so that a magnet can be mounted to an end of the rotation shaft, to enable the giant magnetoresistance sensor to detect a magnetic field; in the case of a rotary transformer, a rotor diameter thereof often needs to be greater than a diameter of the electric motor rotation shaft, in order that the rotary transformer can be mounted. It has also been proposed that the angular position of the rotor be detected by arranging an LED lamp on the rotor; this method similarly needs a large space to mount the associated elements, and the level of precision is not high.
Thus, it is necessary to improve upon existing apparatuses and methods for detecting an angular position of a rotary element.
Content of the invention
An object of the present invention is to provide an apparatus and method for detecting an angular position of a rotary element such that, based on the apparatus and method of the present invention, costs can be lowered.
Another object of the present invention is to provide an apparatus and method for detecting an angular position of a rotary element such that, based on the apparatus and method of the present invention, only a small space is needed to mount the apparatus for detecting an angular position of a rotary element.
Another object of the present invention is to provide an apparatus and method for detecting an angular position of a rotary element such that, based on the apparatus and method of the present invention, the precision of detection of the angular position of the rotary element can be significantly improved.
According to the present invention, an apparatus for detecting an angular position of a rotary element is provided, comprising:
a detectable region disposed on the rotary element; a detection element for detecting the detectable region; and a processing unit for processing a signal from the detection element; characterized in that the detectable region comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner; a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element.
Preferably, the two halves, when opened out in a plane, form a rectangle shape, and the two halves are formed by separation along a diagonal of the rectangle.
Preferably, the two halves are directly formed on the rotary element.
Preferably, the two halves are disposed on a cylindrical shrink ring, and the shrink ring is mounted in a fixed manner on the rotary element.
Preferably, the two halves are a pale-coloured half and a dark-coloured half differentiated by colour.
Preferably, the pale-coloured half is a white half, and the dark-coloured half is a black half.
Preferably, the rotary element is a rotation shaft of an electric motor.
Preferably, the electric motor is a permanent magnet synchronous electric motor, and a pattern formed by the two halves is disposed within a range of every 360° /N in a circumferential direction of the rotation shaft, wherein N is the number of pairs of magnetic poles disposed on a stator of the electric motor.
Preferably, the detection element is an infrared sensor comprising an emitter and a receiver.
Preferably, the apparatus for detecting an angular position of a rotary element further comprises a light blocking shroud covering the infrared sensor and having a slit.
Preferably, the processing unit further comprises:
a power supply line, receiving electrical energy from outside and used for supplying power to the detection element; a signal amplifier for amplifying an optoelectrical signal from the detection element; and
a signal processor for processing a signal amplified by the signal amplifier, wherein the processed signal is supplied to a microcontroller of the rotary element.
Preferably, the power supply line, the signal amplifier and the signal processor are integrated as a printed circuit board.
According to another aspect of the present invention, a method for detecting an angular position of a rotary element is provided, comprising:
disposing a detectable region on the rotary element, wherein the detectable region comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner, and a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element; detecting the detectable region, to acquire the ratio of areas or lengths of regions, detected by the detection element, of the two halves; and processing a signal representing the ratio. Preferably, the processed signal is supplied to a microcontroller of the rotary element.
According to the present invention, the angular position of the rotation shaft can be uniquely determined by the detection element detecting at least one pattern formed by two halves and disposed on the rotation shaft. Thus, not only can the measurement precision be significantly improved, but the apparatus for detecting an angular position of an electric motor rotation shaft has a simple structure, a low cost, and requires little mounting space.
Description of the accompanying drawings
In the drawings:
Fig. 1 is a simplified schematic diagram, schematically showing an electric motor provided with an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention.
Fig. 2 is a three-dimensional schematic diagram of the shrink ring fitted to the rotation shaft of the electric motor in fig. 1.
Fig. 3 is a planar schematic diagram of a shrink ring body after opening out the shrink ring in fig. 2.
Fig. 4 is a schematic diagram showing the projection of detection light onto the opened-out shrink ring body. Fig. 5 schematically shows a processing unit, for processing a signal from the detection element, of an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention.
Particular embodiments
Preferred embodiments of the present invention are described in detail below with reference to examples. Those skilled in the art should understand that these demonstrative embodiments do not imply that any limitation is applied to the present invention.
Fig. 1 is a simplified schematic diagram, schematically showing an electric motor provided with an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention. For simplicity, a housing of the electric motor has been partially omitted in fig. 1. The electric motor 1 in fig. 1 is for example a permanent magnet synchronous electric motor, substantially comprising a stator 5 disposed in a housing 3, and a rotor 7 which is located in a central part of the stator 5 and capable of rotating relative to the stator 5. The rotor 7 comprises a rotation shaft 9 and a rotor core mounted on the rotation shaft 9.
In order to drive the electric motor 1, it is necessary to detect the angular position of the rotor 7 of the electric motor, in order to determine the direction of the magnetic field which should be applied to the stator according to a magnetic field direction of a rotor permanent magnet in the course of rotation. To this end, an apparatus 11 for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention comprises a detectable region 13 disposed on the rotation shaft 9, a detection element 15 for detecting the detectable region, and a processing unit 17 for processing a signal from the detection element. According to a preferred embodiment, the detectable region 13 disposed on the rotation shaft 9 is a shrink ring 19 fixed to the rotation shaft 9. Fig. 2 is a three-dimensional schematic diagram of the shrink ring fitted to the rotation shaft of the electric motor in fig. 1; fig. 3 is a planar schematic diagram of a shrink ring body after opening out the shrink ring in fig. 2. As shown in fig. 2, the shrink ring 19 is a cylindrical sleeve. When the shrink ring 19 has been opened out, a shrink ring body 19a should have the rectangular shape shown in fig. 3. The shrink ring body 19a is designed as a pale-coloured half 21a and a dark-coloured half 21b, along a diagonal 19b of the shrink ring body 19a with the rectangular shape shown in fig. 3. In a preferred embodiment, the pale-coloured half 21a is coated so as to be white, and the dark-coloured half 21b is coated so as to be black. However, it should be understood that the pale colour and the dark colour need not be restricted to white and black, as long as these two parts form regions which can be detected by the detection element in a differentiated manner.
The detection element 15 for detecting the detectable region may be any suitable sensor capable of recognizing a pattern formed by the mutually differentiated pale-coloured half 21a and dark-coloured half 21b on the shrink ring 19. As an example, the detection element 15 for detecting the detectable region is an infrared sensor comprising an infrared emitter and an infrared receiver. Of course, the detection element 15 for detecting the detectable region could also employ a suitable sensor other than an infrared sensor. The detection element 15 for detecting the detectable region may be disposed on a support part 23 fixed to the housing 3 of the electric motor; the distance from the detection element 15 for detecting the detectable region to the shrink ring 19 fixed to the rotation shaft 9 of the electric motor is selected so that the detection element 15 for detecting the detectable region has optimal detection precision. Preferably, the detection element 15 for detecting the detectable region is covered by a light-blocking shroud 25, and the light-blocking shroud 25 has a slit such that only a narrow infrared light beam is projected onto the shrink ring 19. Thus, only very small regions on the shrink ring 19 can be detected, and adjacent regions will not affect detection, therefore the precision of detection can be further improved.
Fig. 4 is a schematic diagram showing the projection of detection light onto the opened-out shrink ring body, and is intended to explain the operating principles of the apparatus for detecting an angular position of an electric motor rotation shaft according to the present invention. The dotted-line box 27 in the figure represents an infrared light beam emitted by an emitter of the detection element 15 for detecting the detectable region and projected onto the shrink ring 19; the infrared light beam is received by a receiver of the detection element 15 for detecting the detectable region after reflection by the pattern formed by the pale- coloured half 21a and the dark-coloured half 21b on the shrink ring 19. Suppose that, when the electric motor is rotating, the pattern formed by the pale-coloured half 21a and the dark-coloured half 21b on the shrink ring 19 moves from left to right relative to the infrared light beam represented by the dotted-line box 27; then, at each moment during rotation of the electric motor rotation shaft through one revolution, i. e. 360° , region areas of the pale-coloured half 21a and the dark-coloured half 21b detected by the infrared light beam both have definite corresponding values, i. e. the ratio of a region area of the pale-coloured half 21a detected by the infrared light beam to a region area of the dark-coloured half 21b detected by the infrared light beam is uniquely determined; therefore, once the ratio of the region area of the pale-coloured half 21a detected by the infrared light beam to the region area of the dark- coloured half 21b detected by the infrared light beam has been acquired, the angular position of the electric motor rotation shaft at the corresponding moment can be learnt or tracked. Of course, it should be understood that, as an alternative to determining the angular position of the electric motor rotation shaft by acquiring the ratio of the region area of the pale-coloured half 21a detected by the infrared light beam to the region area of the dark-coloured half 21b detected by the infrared light beam, it is also possible to determine the angular position of the electric motor rotation shaft by acquiring the ratio of the length of the region of the pale-coloured half 21a detected by the infrared light beam to the length of the region of the dark- coloured half 21b detected by the infrared light beam. In the present application, the “lengths” of the two halves detected should be the lengths of the detected regions of the two halves in a direction parallel to the electric motor rotation shaft.
In the preferred embodiments above, one pale-coloured half 21a and one dark-coloured half 21b are arranged symmetrically along the entire circumference of the shrink ring 19, i. e. within a range of 360° in the circumferential direction; correspondingly, the stator of the electric motor is only provided with one pair of magnetic poles. If the stator of the electric motor is provided with two pairs of magnetic poles, one pale-coloured half 21a and one dark- coloured half 21b are arranged symmetrically along half a circumference of the shrink ring 19, i. e. within a range of every 180° in the circumferential direction. Extending this principle, if the stator of the electric motor is provided with N pairs of magnetic poles, one pale-coloured half 21a and one dark-coloured half 21b are arranged symmetrically along 1/N of the circumference of the shrink ring 19, i. e. within a range of every 360° /N in the circumferential direction. Thus, a pattern formed by one pale-coloured half 21a and one corresponding dark-coloured half 21b respectively corresponds to a corresponding pair of magnetic poles of the stator of the electric motor.
Fig. 5 schematically shows a processing unit, for processing a signal from the detection element, of an apparatus for detecting an angular position of an electric motor rotation shaft according to a preferred embodiment of the present invention. As shown in fig. 5, the processing unit 17 for processing a signal from the detection element comprises a power supply line 25, which receives electrical energy from outside and is used for supplying power to the detection element 15 for detecting the detectable region. The processing unit 17 for processing a signal from the detection element further comprises a signal amplifier 27 for amplifying an optoelectrical signal from the detection element 15 for detecting the detectable region, and a signal processor 29 for processing a signal amplified by the signal amplifier 27. The signal processor 29 processes the optoelectrical signal by means of control software, and converts the optoelectrical signal into a differential signal receivable by a microcontroller of the electric motor. The microcontroller of the electric motor controls a current or voltage applied to the stator of the electric motor according to the differential signal indicating rotation shaft angular position, and thereby controls the direction of a magnetic field generated by the stator of the electric motor. In a preferred embodiment, the power supply line 25, signal amplifier 27 and signal processor 29 of the processing unit 17 for processing a signal from the detection element are all integrated as a printed circuit board. The processing unit 17 for processing a signal from the detection element may be mounted on the housing of the electric motor independently of the detection element 15 for detecting the detectable region, and may also be integrated on a control panel of a control apparatus of the electric motor.
In the preferred embodiments above, the pattern formed by the pale-coloured half 21a and the dark-coloured half 21b is arranged on the shrink ring 19, and the shrink ring 19 is then fixed to the rotation shaft 9 of the electric motor; however, it should be understood that the pattern formed by the pale-coloured half 21a and the dark-coloured half 21b may be arranged on the rotation shaft 9 of the electric motor directly. In addition, as long as the ratio of areas of regions, detected by the detection element, of two mutually differentiated halves is uniquely determined in the circumferential direction, the pattern formed by the pale- coloured half and the dark-coloured half, which are differentiated from each other by colour, may also be replaced by a pattern formed by halves capable of being detected in a mutually differentiated manner by, for example, a smooth half and a rough half, or a protruding half and a depressed half, etc. Thus, the pattern in the present invention is not limited to a pattern formed by colour. Moreover, the region formed by the two halves after being opened out is not restricted to being rectangular.
According to the present invention, the angular position of the rotation shaft can be uniquely determined by the detection element detecting at least one pattern formed by two halves and disposed on the rotation shaft; not only can the measurement precision be significantly improved, but the apparatus for detecting an angular position of an electric motor rotation shaft has a simple structure, a low cost, and requires little mounting space.
The present invention has been described in detail above with reference to specific preferred embodiments. Clearly, the description above and the embodiments shown in the drawings are demonstrative, and should not constitute a restriction of the present invention. For example, although the case of measuring an angular position of an electric motor rotation shaft is taken as an example in the preferred embodiments to describe the present invention, it should be understood that the present invention may be used to measure an angular position of any rotary element. Those skilled in the art should understand that various amendments and changes may be made without departing from the spirit of the present invention, and that such amendments and changes shall not depart from the scope of protection of the present invention.

Claims

Claims
1. Apparatus (11) for detecting an angular position of a rotary element, comprising:
a detectable region (13) disposed on the rotary element; a detection element (15) for detecting the detectable region (13) ; and a processing unit (17) for processing a signal from the detection element (15) ; characterized in that the detectable region (13) comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner; a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element.
2. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the two halves, when opened out in a plane, form a rectangle shape, and the two halves are formed by separation along a diagonal of the rectangle.
3. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the two halves are directly formed on the rotary element.
4. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the two halves are disposed on a cylindrical shrink ring (19), and the shrink ring (19) is mounted in a fixed manner on the rotary element.
5. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the two halves are a pale-coloured half (21a) and a dark-coloured half (21b) differentiated by colour.
6. Apparatus (11) for detecting an angular position of a rotary element according to Claim 5, characterized in that the pale- coloured half (21a) is a white half, and the dark-coloured half (21b) is a black half.
7. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the rotary element is a rotation shaft of an electric motor.
8. Apparatus (11) for detecting an angular position of a rotary element according to Claim 7, characterized in that the electric motor is a permanent magnet synchronous electric motor, and a pattern formed by the two halves is disposed within a range of every 360° /N in a circumferential direction of the rotation shaft, wherein N is the number of pairs of magnetic poles disposed on a stator of the electric motor.
9. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the detection element (15) is an infrared sensor comprising an emitter and a receiver.
10. Apparatus (11) for detecting an angular position of a rotary element according to Claim 9, characterized by further comprising a light-blocking shroud (25) covering the infrared sensor and having a slit.
11. Apparatus (11) for detecting an angular position of a rotary element according to Claim 1, characterized in that the processing unit (17) comprises:
a power supply line (25), receiving electrical energy from outside and used for supplying power to the detection element (15) ; a signal amplifier (27) for amplifying an optoelectrical signal from the detection element (15) ; and
a signal processor (29) for processing a signal amplified by the signal amplifier (27), wherein the processed signal is supplied to a microcontroller of the rotary element.
12. Apparatus (11) for detecting an angular position of a rotary element according to Claim 11, characterized in that the power supply line (25), the signal amplifier (27) and the signal processor (29) are integrated as a printed circuit board.
13. Method for detecting an angular position of a rotary element, comprising:
disposing a detectable region (13) on the rotary element, wherein the detectable region (13) comprises at least one pattern, disposed on the rotary element in a circumferential direction and formed by two halves capable of being detected by the detection element in a differentiated manner, and a ratio of areas or lengths of regions, detected by the detection element, of the two halves is uniquely determined within a range of each said pattern in the circumferential direction of the rotary element; detecting the detectable region (13), to acquire the ratio of areas or lengths of regions, detected by the detection element, of the two halves; and processing a signal representing the ratio.
14. Method for detecting an angular position of a rotary element according to Claim 13, characterized in that the processed signal is supplied to a microcontroller of the rotary element.
15. Method for detecting an angular position of a rotary element according to Claim 13, characterized in that the two halves, when opened out in a plane, form a rectangle shape, and the two halves are formed by separation along a diagonal of the rectangle.
16. Method for detecting an angular position of a rotary element according to Claim 13, characterized in that the two halves are directly formed on the rotary element.
17. Method for detecting an angular position of a rotary element according to Claim 13, characterized in that the two halves are disposed on a cylindrical shrink ring (19), and the shrink ring (19) is mounted in a fixed manner on the rotary element.
18. Method for detecting an angular position of a rotary element according to Claim 13, characterized in that the two halves are a pale-coloured half (21a) and a dark-coloured half (21b) differentiated by colour.
19. Method for detecting an angular position of a rotary element according to Claim 13, characterized in that the rotary element is a rotation shaft of an electric motor.
20. Method for detecting an angular position of a rotary element according to Claim 19, characterized in that the electric motor is a permanent magnet synchronous electric motor, and a pattern formed by the two halves is disposed within a range of every 360° /N in a circumferential direction of the rotation shaft, wherein N is the number of pairs of magnetic poles disposed on a stator of the electric motor.
PCT/EP2019/062197 2018-05-17 2019-05-13 Apparatus and method for detecting angular position of rotary element WO2019219599A1 (en)

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