GB2105475A - Determining the radial position of a rotating body - Google Patents

Determining the radial position of a rotating body Download PDF

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Publication number
GB2105475A
GB2105475A GB08224568A GB8224568A GB2105475A GB 2105475 A GB2105475 A GB 2105475A GB 08224568 A GB08224568 A GB 08224568A GB 8224568 A GB8224568 A GB 8224568A GB 2105475 A GB2105475 A GB 2105475A
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GB
United Kingdom
Prior art keywords
rotating body
magnetic poles
wound
magnetic
determining
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08224568A
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GB2105475B (en
Inventor
Hisayuki Hirayama
Yuji Tanaka
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Seiko Instruments Inc
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Seiko Instruments Inc
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Filing date
Publication date
Application filed by Seiko Instruments Inc filed Critical Seiko Instruments Inc
Publication of GB2105475A publication Critical patent/GB2105475A/en
Application granted granted Critical
Publication of GB2105475B publication Critical patent/GB2105475B/en
Expired legal-status Critical Current

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    • 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
    • G01B7/004—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points
    • 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
    • G01B7/31—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes

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

Abstract

A device for determining the radial position of a rotating body (200), said device comprising a ring core (220) having at least four angularly spaced apart wound magnetic poles (201, 204, 207, 210) which are symmetrically arranged with respect to two orthogonal axes (X, Y), the ring core (220) having a plurality of angularly spaced apart non-wound magnetic poles (202, 203, 205, 206, 208, 209, 211, 212) which are intercalated with the wound magnetic poles (201, 204, 207, 210) so that, in use, a plurality of magnetic paths are formed each of which comprises a wound pole, a non- wound pole and the rotating body, and position determining means electrically connected to the windings of the wound magnetic poles (201, 204, 207, 210) for determining the radial position of the rotating body (200). <IMAGE>

Description

SPECIFICATION Device for determining the radial position of a rotating body This invention concerns a device for determining the radial position of a rotating body.
According to the present invention, there is provided a device for determining the radial position of a rotating body, said device comprising a ring core having at least four angularly spaced apart wound magnetic poles which are symmetrically arranged with respect to two orthogonal axes, the ring core having a plurality of angularly spaced apart non-wound magnetic poles which are intercalated with the wound magnetic poles so that, in use, a plurality of magnetic paths are formed each of which comprises a wound pole, a non-wound pole and the rotating body, and position determining means electrically connected to the windings of the wound magnetic poles for determining the radial position of the rotating body.
Preferably, the position determining means produces a position determining signal by obtaining the difference in the outputs from two radially oppositely disposed wound magnetic poles.
Preferably, there are two non-wound magnetic poles between each pair of adjacent wound magnetic poles.
The invention is illustrated, merely by way of example, in the accompanying drawings, in which: Figure 1 is a diagrammatic view of a known device for determining the radial position of a rotating body, Figure 2 is a diagrammatic view of part of a device according to the present invention for determining the radial position of a rotating body, and Figure 3 is a block diagram of another part of the device shown in Figure 2.
Figure 1 is a view illustrating the principle of operation of a known magnetic type position detector. The position of a rotating body 100 is detected by means of U-shaped magnetic paths 101 to 108. The operation will now be described with reference to the determination of the position of the rotating body 100 with respect to the X-axis. The U-shaped magnetic paths are arranged in pairs which are symmetrical with respect to the X-axis and the Y-axis, respectively, each U-shaped magnetic path making an angle of a radians with respect to the respective axis. The position of the rotating body 100 with respect to the X-axis can be detected by means of the Ushaped magnetic paths 101, 102, 103 and 104.
The signals in the magnetic paths 101, 102 and those in the magnetic paths 103, 104 are added to each other at this time, and the position of the rotating body 100 with respect to the X-axis is determined on the basis of the difference between these two added signals. This operation is also applicable to the determination of the position of the rotating body 100 with respect to the Y-axis.
However, if the rotation of the rotating body is accompanied by vibration, this vibration arises from the harmonics components of the oscillation frequency of the rotating body. Moreover, even if the rotating body rotates without vibration, then if the rotating body is not perfectly round, the oscillation frequency due to the harmonics components depend upon the configuration of the rotating body. However, in such circumstances, it is only necessary to determine the fundamental frequency with high accuracy.
As shown in Figure 1, if the pairs of U-shaped magnetic paths 101 to 108 are arranged so as to be symmetrical with respect to the X-axis and the Y-axis respectively, it is obvious that the evenorder harmonics components cannot be determined by calculation. The odd-order harmonics components are not detected when the following equation is satisfied between the angle a with respect to the axes and the odd number n indicating the odd-order harmonics: 7t cg 2n The relationship between the detected output x along the X-axis, a and n is represented by the following equation: x=K cos na, where K is a constant.
In the case of the detected output y along the Y-axis, the above equation is applicable by changing x to y.
In the prior art, in order to realize the arrangement shown in Figure 1, a separate winding is provided for each of paths 101 to 108 and the angle a is determined by fixing each magnetic circuit in position. In order not to detect the third-order harmonics component of the fundamental vibration frequency, the angle a is selected to be 7r/6. However, this has the disadvantage either that there is little space for the windings if the device is a small one, or the number of magnetic poles has to be increased.
Figure 2 shows an embodiment of a device for determining the radial position of a rotating body according to the present invention. The device has a ring core 220 having magnetic poles 201,207 arranged on the X-axis and magnetic poles 210, 204 arranged on the Y-axis, each of the poles 201,204, 207, 210 being angularly spaced apart and provided with a respective winding. The wound magnetic poles 201,204, 207, 210 are intercalated with non-wound magnetic poles 202, 203, 205, 206, 208, 209, 211,212, there being two non-wound magnetic poles between adjacent wound magnetic poles. The assembly of wound and non-wound magnetic poles 201 to 212 is arranged so as to be symmetrical with respect to the X-axis and to the Y-axis.Moreover, a high frequency current flows through the windings and the directions of the magnetic fluxes appearing at each instant at the magnetic poles 201,207,210, and 204 are the same on each side of a rotating body 200.
The invention will now be described with reference to the determination of the radial position of the rotating body 200 with respect to the X-axis. When the rotating body 200 is placed at a central position, the magnetic fluxes produced from the wound poles 201, 207,210, and 204 pass through the body 200 to the nonwound poles 202, 203, 205, 206, 208, 209, 211 and 212. When determining the displacement of the body 200 with respect to the X-axis, since this determination is based on the difference between the signal in the positive direction and the signal in the negative direction, the detected output concerning the Y direction is not produced.Thus the magnetic poles 201,202, 212, 203 and 211 are to be considered as the poles relevant to determination of the positive direction in the Xaxis and the magnetic poles 207, 208, 209, 206 and 205 are to be considered as the poles relevant to determination of the negative direction in the X-axis. For the positive direction, four magnetic circuits are provided by the pole 201 rotating body 200 and pole 202; the pole 201, rotating body 200 and pole 203; the pole 201, rotating body 200 and pole 212; and the pole 201, rotating body 200 and pole 211. Similarly for the negative direction, four magnetic circuits are provided by the magnetic poles 207, 205, 206, 208 and 209 and the rotating body 200.
Assuming that the angles made between the X-axis and the central axis of each U-shaped magnetic path which is formed by the poles 201 and 202,201 and 212,207 and 208, and 207 and 206 respectively, are a radians, and assuming that the angles made between the Xaxis and the central axis of the U-shaped magnetic paths which are formed by the poles 201 and 203,201 and 211,207 and 209, and 207 and 205 respectively are p radians, then in practice one can consider that there are two magnetic poles in which the angle made by the Xaxis and a central axis of a U-shaped magnetic path formed by the use of the pole 201 is c radians and that these are symmetrical with respect to the positive direction of the X-axis, and thus are radially oppositely disposed. This analysis will also be applicable to the pole 207.After all, there are two sets of the centres between the Ushaped magnetic poles, and each centre makes an angle of c radians about the positive portion of the X axis and is symmetrical about the X axis.
The centres act as if two sets of centres were in the negative direction of the X-axis in a similar way.
The detection signal indicating the position of the rotating body can be obtained by the difference between the added signals for two sets in the positive direction of the X-axis, and the added signals for the two sets in the negative direction of the X-axis. There is the following relationship between a, b and c.
c=(a+b)/2.
Assuming that the magnetic poles are placed as shown in Figure 2 in which a=/1 2 and b=7r/6, then c will be 'r/8. In this case, the angle at which the third harmonic component can be eliminated is 7t/6. Although the elimination of the third harmonic component is not so complete when c=,r/8, since x=K cos 37r/8, the amount of the third harmonic component which is detected is less than 40% thereof. In addition, a harmonics component of at least the fourth harmonics will be detected in accordance with the following equation x=K cos nnr/8.
With regard to the positive direction of the Yaxis, the same theory as that relating to the X-axis is applicable by taking account of the poles 208, 209, 210, 211 and 212, and is also applicable to the negative direction of the Y-axis by taking acount of the poles 202, 203, 204, 205 and 206.
In this system, the X-axis and the Y-axis are not fixed, priority is given to the third harmonics components, and one does not have to provide a number of magnetic poles in a narrow space. That is, in the device of the present invention, the magnetic poles for the X-axis and for the Y-axis are used in common, so that the narrow space is effectively used. Moreover, the decrease in the third harmonics component is not less than 60%, and the even-order harmonics are not detected.
Therefore, a more effective position detector for determining the radial position of a rotating body can be provided, The present invention is particularly useful in connection with determining the radial position of a rotating body constituted by a magnetic bearing or an air bearing. However, the present invention is not limited to this, the foregoing description relating merely to one embodiment of the present invention. Therefore, with regard to the number of the magnetic poles, the angular disposition of the ring core 220, or to other features, the present invention is not limited to the structure of the illustrated embodiment.
In Figure 3 there is shown a circuit block 301 which is electrically connected (by means not shown) to the winding of the magnetic pole whose output is representative of the positive direction of the X or Y-axis, and a circuit block 302 which is electrically connected (by means not shown) to the winding of the magnetic pole whose output is representative of the negative direction of the X or Y-axis. As will be appreciated, these magnetic poles will be radially oppositely disposed.
The difference between the output signals from the blocks 301 and 302 is obtained by a block 303.
Let us assume that the position with respect to the X-axis is to be determined. Assuming that each output from the blocks 301 and 302 when the rotating body is at an initial position is x, the output from the block 301 when the rotating body is moved by Ax is x+Ax, and the output from the block 302 when the rotating body is so moved is x-Ax. Thus the output of the block 303 becomes 2Ax when the difference is calculated between the outputs of the blocks 301 and 302.
At this time, the differential output level of the blocks 301,302 with respect to the Y-axis is zero since the direction of the Y-axis is perpendicular to the direction of movement along the X-axis.
The output from the block 303 is transmitted to an indicator (not shown) which indicates the radial position of the rotating body.
Since the signals concerning the positive and the negative directions of each axis were taken out independently of each other in the known system, there was little output arising from a signal change and the noise level could not be reduced. In the device of the present invention, however, the magnitude of the output arising from the changing component becomes twice as great compared with that of the known system and the same phase components are cancelled.
Therefore, the noise level can be reduced and the changing component in the perpendicular direction is not detected.

Claims (6)

Claims
1. A device for determining the radial position of a rotating body, said device comprising a ring core having at least four angularly spaced apart wound magnetic poles which are symmetrically arranged with respect to two orthogonal axes, the ring core having a plurality of angularly spaced apart non-wound magnetic poles which are intercalated with the wound magnetic poles so that, in use, a plurality of magnetic paths are formed each of which comprises a wound pole, a non-wound pole and the rotating body, and position determining means electrically connected to the windings of the wound magnetic poles for determining the radial position of the rotating body.
2. A device as claimed in claim 1 in which the position determining means produces a position determining signal by obtaining the difference in the outputs from two radially oppositely disposed wound magnetic poles.
3. A device as claimed in claim 1 or 2 in which there are two non-wound magnetic poles between each pair of adjacent wound magnetic poles.
4. A device for determining the radial position of a rotating body substantially as hereinbefore described with reference to and as shown in Figures 2 and 3.
5. A device for detecting a position in the radial direction of a rotating body characterized in that there are provided four magnetic poles with windings provided on orthogonal two axes, Ushaped magnetic path composed of the windingless magnetic pole, the magnetic pole with winding and ring core which is formed at least four magnetic poles at the place symmetry with respect to the orthogonal axes, a magnetic path is formed by the use of said U-shaped magnetic path and a rotating body.
6. A device as claimed in claim 5 wherein a position detecting signal is differentially detected from the winded magnetic poles which are faced with respect to the radial direction each other.
GB08224568A 1981-09-04 1982-08-26 Determining the radial position of a rotating body Expired GB2105475B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13955281A JPS5841304A (en) 1981-09-04 1981-09-04 Device for detecting position in direction of radius of rotary body

Publications (2)

Publication Number Publication Date
GB2105475A true GB2105475A (en) 1983-03-23
GB2105475B GB2105475B (en) 1985-07-03

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GB08224568A Expired GB2105475B (en) 1981-09-04 1982-08-26 Determining the radial position of a rotating body

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JP (1) JPS5841304A (en)
DE (1) DE3232870A1 (en)
FR (1) FR2512544A1 (en)
GB (1) GB2105475B (en)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2630542A1 (en) * 1988-04-22 1989-10-27 Mecanique Magnetique Sa Inductive sensor with harmonic rejection for detecting the radial displacements of a rotor
US5194805A (en) * 1989-12-29 1993-03-16 National Aerospace Laboratory, Ebara Research Co., Ltd. Inductance-type displacement sensor for eliminating inaccuracies due to external magnetic fields
EP0589240A1 (en) * 1992-09-12 1994-03-30 SMS HASENCLEVER GmbH Horizontal metal-extrusion press
US5456123A (en) * 1994-01-26 1995-10-10 Simmonds Precision Products, Inc. Static torque measurement for rotatable shaft
US5508609A (en) * 1993-06-30 1996-04-16 Simmonds Precision Product Inc. Monitoring apparatus for detecting axial position and axial alignment of a rotating shaft
US5514952A (en) * 1993-06-30 1996-05-07 Simmonds Precision Products Inc. Monitoring apparatus for rotating equipment dynamics for slow checking of alignment using plural angled elements
US5696444A (en) * 1994-03-04 1997-12-09 Crane Co. Monitoring system for detecting axial and radial movement of a rotating body independent of rotational position
US5955880A (en) * 1996-12-05 1999-09-21 Beam; Palmer H. Sealless pump rotor position and bearing monitor
FR2934895A1 (en) * 2008-08-05 2010-02-12 Thales Sa RADIAL POSITION SENSOR DEVICE EXTENDED BY MORE THAN 90 °
CN106533108A (en) * 2016-12-29 2017-03-22 上海世昱电子技术有限公司 Rotary transformer and rotating body with same
CN106655685A (en) * 2017-03-01 2017-05-10 上海世昱电子技术有限公司 Rotary transformer and rotating body equipped with same
CN106712428A (en) * 2017-01-16 2017-05-24 上海世昱电子技术有限公司 Rotary transformer and rotation body with same
CN106712427A (en) * 2016-12-29 2017-05-24 上海世昱电子技术有限公司 Rotary transformer and rotating body provided with same
CN107276323A (en) * 2017-08-01 2017-10-20 上海世昱电子技术有限公司 A kind of angle sensing device, rotary body and electric motor system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2570488B1 (en) * 1984-09-19 1987-01-09 Europ Propulsion DEVICE FOR MAGNETIC DETECTION OF RADIAL MOVEMENTS OF A ROTOR
US5925951A (en) 1998-06-19 1999-07-20 Sundstrand Fluid Handling Corporation Electromagnetic shield for an electric motor

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US3124271A (en) * 1964-03-10 Timer controlled pressure operated dispenser
CH251155A (en) * 1945-07-27 1947-10-15 Intercito Holding Device for detecting the eccentricity of covered metal rods and wires with respect to the covering.
GB641674A (en) * 1947-11-24 1950-08-16 Laszlo Urmenyi Device for measuring the eccentricity of coated or covered cables, wires and rods
US2805677A (en) * 1953-04-23 1957-09-10 Curtiss Wright Corp Detector for misalinement of rotating body
US4114960A (en) * 1973-01-18 1978-09-19 Societe Europeenne De Propulsion Radial displacement detector device for a magnetic bearing
DE2537597A1 (en) * 1975-08-23 1977-03-03 Padana Ag ELECTROMAGNETIC STORAGE DEVICE
DE2732024C3 (en) * 1977-07-15 1980-09-04 Deutsche Forschungs- Und Versuchsanstalt Fuer Luft- Und Raumfahrt E.V., 5000 Koeln Circuit arrangement for the digital display of the angular position of the rotor of a resolver
US4245869A (en) * 1978-08-07 1981-01-20 Padana Ag Magnetic bearings
FR2440574A1 (en) * 1978-10-05 1980-05-30 Artus POSITION SERVO DEVICE

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2630542A1 (en) * 1988-04-22 1989-10-27 Mecanique Magnetique Sa Inductive sensor with harmonic rejection for detecting the radial displacements of a rotor
US5194805A (en) * 1989-12-29 1993-03-16 National Aerospace Laboratory, Ebara Research Co., Ltd. Inductance-type displacement sensor for eliminating inaccuracies due to external magnetic fields
EP0589240A1 (en) * 1992-09-12 1994-03-30 SMS HASENCLEVER GmbH Horizontal metal-extrusion press
US5421181A (en) * 1992-09-12 1995-06-06 Sms Hasenclever Gmbh Horizontal metal extrusion press
US5508609A (en) * 1993-06-30 1996-04-16 Simmonds Precision Product Inc. Monitoring apparatus for detecting axial position and axial alignment of a rotating shaft
US5514952A (en) * 1993-06-30 1996-05-07 Simmonds Precision Products Inc. Monitoring apparatus for rotating equipment dynamics for slow checking of alignment using plural angled elements
US5456123A (en) * 1994-01-26 1995-10-10 Simmonds Precision Products, Inc. Static torque measurement for rotatable shaft
US5696444A (en) * 1994-03-04 1997-12-09 Crane Co. Monitoring system for detecting axial and radial movement of a rotating body independent of rotational position
US6107794A (en) * 1994-03-04 2000-08-22 Crane Co. Monitoring system for detecting axial and radial movement of a rotating body independent of rotational position
US5955880A (en) * 1996-12-05 1999-09-21 Beam; Palmer H. Sealless pump rotor position and bearing monitor
FR2934895A1 (en) * 2008-08-05 2010-02-12 Thales Sa RADIAL POSITION SENSOR DEVICE EXTENDED BY MORE THAN 90 °
EP2154486A1 (en) * 2008-08-05 2010-02-17 Thales Angular position sensor with a detection angle larger than 90°
US8032325B2 (en) 2008-08-05 2011-10-04 Thales Device for sensing a radial position spread over more than 90 degrees
CN106533108A (en) * 2016-12-29 2017-03-22 上海世昱电子技术有限公司 Rotary transformer and rotating body with same
CN106712427A (en) * 2016-12-29 2017-05-24 上海世昱电子技术有限公司 Rotary transformer and rotating body provided with same
CN106533108B (en) * 2016-12-29 2024-04-26 苏州昱泽智能科技有限公司 Resolver and rotating body having the same
CN106712428A (en) * 2017-01-16 2017-05-24 上海世昱电子技术有限公司 Rotary transformer and rotation body with same
CN106655685A (en) * 2017-03-01 2017-05-10 上海世昱电子技术有限公司 Rotary transformer and rotating body equipped with same
CN107276323A (en) * 2017-08-01 2017-10-20 上海世昱电子技术有限公司 A kind of angle sensing device, rotary body and electric motor system
CN107276323B (en) * 2017-08-01 2024-04-19 苏州昱泽智能科技有限公司 Angle detection equipment, rotating body and motor system

Also Published As

Publication number Publication date
FR2512544A1 (en) 1983-03-11
GB2105475B (en) 1985-07-03
JPS5841304A (en) 1983-03-10
JPH0221521B2 (en) 1990-05-15
DE3232870A1 (en) 1983-03-24

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Date Code Title Description
PE20 Patent expired after termination of 20 years

Effective date: 20020825