WO2009088378A1

WO2009088378A1 - Magnetostrictive indicator

Info

Publication number: WO2009088378A1
Application number: PCT/SK2008/050013
Authority: WO
Inventors: Branislav Anwarzai; Stefan Blasko; Vojtech KOLLÁR; Ivan Kneppo; Milan Risko; Zdenko Figura
Original assignee: Psl, A.S.
Priority date: 2008-01-11
Filing date: 2008-09-03
Publication date: 2009-07-16
Also published as: SK500012008A3

Abstract

The aim of the Invention is following-up of angle displacement of mutually rotating parts. In a perimeter groove (71) formed in one of mutually rotating parts (7), a magnetostrictive conductor (6) in an insulating casing (5) is situated, forming a magnetostrictive waveguide (1) that may consist of more segments (Ia, Ib). The magnetostrictive waveguide (1) is provided, on its beginning (11), with a sensing terminal (2), and on its end (12), with a reference terminal (3). In the casing (21) of the sensing terminal (2), a magnetostrictive waveguide (1) is fixed, its beginning (11) fitting to the indicator (22) of mechanical oscillations, to which contacts (23) for connecting of converter (41) of evaluating module (4) fit, to the output of which a correlation unit (42) is connected, having on its output an unit (43) for evaluating of propagation time of mechanical oscillations and for displaying an actual angle displacement.

Description

Magnetostrictive indicator

Technical Field

The present application relates to a magnetostrictive indicator suitable for following-up of an angle displacement of mutually rotating parts, particularly of bearing rings. Background Art

Various designs aimed on the following-up the angle displacement of mutually rotating parts are known, that function on the resistive, electrooptical, inductive and magnetic principle. The disadvantages of these designs are the error, occuring in the conversion and the incompactness with rotating parts. The known designs forming un compact system together with rotating parts function in the incremental mode, consequently they do not enable the absolute measuring of an displacement angle. Their disadvantage consists also in that, that in case of an interrupted electric energy supply, in case of an accidental interference etc., the whole scanning process must be returned to the beginning of the measuring. From the US 6,863,442 , an incremental sensor is known, consisting of a corrugated strip of the non-retentive material fixed on the outer perimeter of the inner bearing ring, and of a measuring head, fixed on the inner perimeter of the outer bearing ring and being sensitive to the change of the magnetic flux caused by the alternating of tops and valleys of the corrugated strip moving under the measuring head during the rotating of the inner bearing ring. From the US 5073711, a design of an sensor is known, according to which the angular scale in the binary code, fixed on the rotating part, is formed by an optically readable medium. The measuring head scans data in corresponding channels of the encoded scale by means of several optical rays. The output indicating the angular displacement is done in the digital form. From the optical principle follows the limited applicability in measuring of the mutual displacement of two parts in the polluted environment.

From US 4,238,844 and US 6,906,512, designs of sensors for following-up the mutual position of two objects are known based on the magnetostrictive principle. These designs concern however only the following-up of the mutual position of two linearly moving objects. Their use in the metallic surroundings, where the scanned rotary parts are made of metal, complicates the arrangement of the magnetic circuit in the place of the permanent magnet which determinates the angular displacement of one of the parts, and the electric current supply to the end of an ultrasonic waveguide through the metallic covering tube of the sensor is not possible, as it is realized in these known designs. The disadvantage consists also in that, that by a simple turning of the linear sensor, a relatively long ,,idle band" would occure, in which it would not be possible to measure the position of the mutual displacement of two parts. Disclosure of Invention

The said disadvantages are in the considerable part eliminated by the magnetostrictive indicator for the following-up of the displacement angle ot mutually rotating parts, formed by the magnetostrictive waveguide situated on one of the rotating parts, to the beginning of which an impulse generator and an indicator of mechanical oscillations, and on the other rotating part, a permanent magnet is located, whereby signals from the indicator of mechanical oscillations are supplied into an evaluating module, where they are modified by a converter and then processed in an unit for time measurement of mechanical oscillation propagation and for displaying of an actual angle displacement according to this Invention, the disclosure of which consists in that, that the magnetostrictive waveguide is located in the ring groove, formed in one of the mutually rotating parts, the ring groove being advantageously filled with an insulating compound. In this way, the disadvantageous influence of impurities occuring in the measured surroundings on the measuring accuracy will be prevented, the transfer of oscillations of rotating parts to the magnetostrictive waveguide will be prevented and the position of the magnetostrictive waveguide in the required distance from the permanent magnet, fixed on the other rotating part, will be secured.

The disclosure of the Invention consists further in that, that the beginning and the end of the magnetostrictive waveguide overlap one another, in that way the so called ,,idle band" , occuring during the exciting of a current impulse, is eliminated, what enables to measure the mutual position of the rotating parts with the angle of their displacement of 360° and more.

In order to prevent the transfer of oscillations of a ferromagnetic conductor of the magnetostrictive waveguide into the surroundings, which would damp the propagation of the ultrasonic impulse, the disclosure of the Invention consists also in that, that the magnetostrictive waveguide is formed by a ferromagnetic magnetostrictive conductor, located in an insulating casing.

For the purpose of preventing the attenuation of the detected signal under the interference level by the parasitic magnetic fields and for the measuring accelerating, the disclosure of the Invention consists further in that, that the magnetostrictive waveguide consists from at least two segments, where the exciting and following-up of the ultrasonic impulse and the evaluation of the position are performed in the parallel mode. In order to eliminate the so called ,,idle band" in case of using the magnetostrictive waveguide consisting of more segments, the disclosure of the Invention consists further in that, that the beginnings of the segments as well as the ends of the segments overlap one another.

In order to fix the position of the ends of the magnetostrictive waveguide in the required distance in the perimeter groove, and in order to detach them from impurities following from the surroundings, the disclosure of the Invention consists further in that, that the magnetostrictive waveguide is provided with a sensing terminal on its beginning, and with a reference terminal on its end.

The disclosure of the Invention consists further in that, that the sensing terminal is formed by a casing, in which the magnetostrictive waveguide is fixed, the beginning of the magnetostrictive waveguide contacting an indicator of mechanical oscillations, against which contacts for the connection of a converter of an evaluating module contact.

The disclosure of the Invention consists also in that, that the reference terminal is formed by a casing, in which the ending of the magnetostrictive waveguide is fixed, by the side of which a reference magnet in the casing is fixed, the purpose of this magnet being - in the defined position from the end of the waveguide - as a result of the magnetic field to generate the reference end impulse, by means of which the influence of the temperature of the surroundings on the segment from the calculation of the mutual position of rotating parts will be eliminated.

At least, the disclosure of the Invention consists in that, that to the output of the converter of the evaluating module, a correlation unit is connected, to the output of which an unit for evaluating of the propagation time of mechanical oscillations and for displaying an actual angle displacement is connected. Through the evaluation of the ultrasonic impulse by means of the correlation circuit, the elimination of disturbing influences of the surroundings, mainly in the area of high voltage distribution networks, during the stormy activities, etc. and the increased measuring accuracy will be achieved.

The advantages of the magnetostrictive indicator according to the Invention consist in that, that they form a compact whole with the rotating part, the angle of displacement of which will be measured, that the magnetostrictive indicator enables the absolute measuring of the angle of displacement of rotating parts, geometrical dimensions of which represent concerning the order of tens to hundreds centimetres, that it is applicable in heavy contaminated surroundings formed by parts made of metal, that it is resistant against mechanical influences of the surroundings and evaluates a number of successive impulses, in order to eliminate accidental erroneous impulses. Brief Description of Drawings

The Invention will be close explained by means of drawings, from which FIG. 1. schematically demonstrates the magnetostrictive waveguide formed by one segment, FIG. 2. schematically demonstrates the magnetostrictive waveguide formed by two segments, FIG. 3. demonstrates the longitudinal section of the bearing ring with the build-in magnetostrictive waveguide, FIG. 4. demonstrates the close-up view A demonstrated in the FIG. 3., FIG.5. schematically demonstrates the magnetostrictive indicator in the developped form with the block diagram of the evaluating circuit, FIG. 6. demonstrates the axonometric view on the sensing terminal in the closed state,. FIG. 7. demonstrates the axonometric view on the opened body of the sensing terminal, FIG. 8. demonstrates the axonometric view on the opened cover of the sensing terminal, FIG. 9. demonstrates the lateral view on the sensing terminal in the closed state, FIG.10. demonstrates the section B-B demonstrated in the FIG. 9. , FIG. 11. demonstrates the section A-A demonstrated in the FIG. 9., FIG. 12. demonstrates the axonometric view on the reference terminal, FIG. 13. demonstrates the axonometric view on the opened body of the reference terminal , FIG. 14 demonstrates the axonometric view on the opened cover of the reference terminal, FIG. 15. demonstrates the lateral view on the reference terminal, FIG. 16. demonstrates the section B-B demonstrated in the FIG. 15., and FIG.17. demonstrates the section A-A demonstrated in the FIG. 15. Example of Carrying Out the Invention The magnetostrictive indicator is formed by a magnetostrictive waveguide 1 situated on one of the rotating parts, and by the permanent magnet 9, situated on the other of rotating parts. To the beginning JJ_. of the magnetostrictive waveguide 1, a generator JJ) of electric impulses is connected, which is electrically interconnected with the end J_2 of the magnetostrictive waveguide 1. The beginning JJ_. of the magnetostrictive waveguide 1 is provided with an indicator 22, to which the evaluating module 4 is connected, formed by a converter 4J_ of mechanical oscillations, by a correlation unit 42 and by an unit 43 for evaluating of the propagation time of mechanical oscillations and for displaying an actual angle displacement, as demonstrated in the FIG.5. In case that it is necessary to measure the mutual position of the rotating parts with an angle of displacement of 360° and more, the beginning JJ_. and the end J2_. of the magnetostrictive waveguide 1 overlap one another, as demonstrated in the FIG. 1. The magnetostrictive waveguide 1 may consist of more segments Ja, Jb, as demonstrated in the FIG. 2, and in that case, the beginnings 11a. l ib of the segments Ja, Jb overlap one another, as well as the ends 12a. 12b of the segments Ja, Jb overlap one another. The building-in of the magnetostrictive waveguide 1 into the ring 7 of a radial thrust bearing with the practical application of an magnetostrictive indicator for following-up an actual mutual angle displacement of the rings of the radial thrust bearing is demonstrated in the FIG.3 and FIG. 4. The perimeter groove 21, formed in the bearing ring 7, is filled with an insulating compound 8, in which the magnetostrictive waveguide 1 is situated, formed by a ferromagnetic magnetostrictive conductor 6_ which is situated in an insulating casing 5_ , and the perimeter groove TJ_. is covered with the cover 72. In case that the ferromagnetic magnetostrictive conductor 6 has a hollow section, the exciting conductor (A_. is situated in its cavity, as demonstrated in the FIG. 13 and FIG. 16. The magnetostrictive waveguide 1 is provided on its beginning H with the sensing terminal 2 and on its end 12 with the reference terminal 3_. The sensing terminal 2 consists of the casing 21, formed by the body 211 and by the cover 212. that are joint together by a bolt 1_3 and by a nut JA In the body 211. the indicator of mechanical oscillations 22 is situated, to which a ferromagnetic conductor 6 of the magnetostrictive waveguide J_contacts. The ferromagnetic conductor 6 of the magnetostrictive waveguide J_is fixed in the sensing terminal 2 against its angle displacement and shifting in its insulating casing 6 by means of an arresting element 24. In the body 211. contacts 23 for the connection of the converter 41 of the evaluating module 4_ further are situated, contacting the indicator of mechanical oscillations 22, as demonstrated in the FIG. 7 and FIG. 10. The reference terminal 3_. consists of the caising 31, formed by the body 311 and by the cover 312. that are joint together by the bolt J_3 and by the nut J_4. In the reference terminal 3_^ the end J_2 of the magnetostrictive waveguide is fixed 1 , close by which the reference magnet 32 in its casing 31 is situated.

The magnetostrictive indicator measures, in a contactless mode, the position of the permanent magnet, situated on one of the rotating parts, by means of the propagation time of the mechanical impulse, caused by the interaction between magnetic fields in the magnetostrictive conductor 6 of the magnetostrictive waveguide 1. To the ferromagnetic magnetostrictive conductor 6, a short current impulse by means of the generator JJ) is supplied, this impulse exciting the magnetic field on the whole length of the magnetostrictive conductor 6. By now, in certain place, the axial magnetic field of the permanent magnet actions, which is placed near to the surface of the magnetostrictive waveguide 1. The interaction of the magnetic field of the permanent magnet and of the the magnetic field of the magnetostrictive conductor 6_excites in the ferromagnetic magnetostrictive conductor 6 a torsion magnetostrictive impulse, that propagates - as a mechanical oscillation with an accustic velocity - from the place of its formation to both ends of the magnetostrictive conductor 6. By the indicator 22, which is situated on the beginning JJ_. of the magnetostrictive waveguide 1, the mechanical oscillation will be intercepted, and from the time lag from the pulsing of the exciting current impulse and from the known propagation velocity of the mechanical oscillation in the respective ferromagnetic material of the magnetostrictive conductor O₄ the position of the place of the mechanical oscillation formation and - in that way - the position of the permanent magnet towards the beginning JJ_. of the magnetostrictive waveguide 1 - can be determined. Signals from the indicator 22 of the ultrasonic impulse 9 are adjusted - by means of the converter 41- and are conducted through the correlation unit 42 into the unit 43 for evaluating the proagation time of mechanical oscillations and for displaying of the actual displacement angle.

Claims

1. Magnetostrictive indicator for following-up of an angle displacement of mutually rotating parts, formed by a magnetostrictive waveguide situated on one of the rotating parts, to which a generator of electric impulses and an indicator of mechanical oscilations are connected and on the other of rotating parts, a permanent magnet is situated, whereby signals from the indicator of mechanical oscillations are supplied into an evaluating module, where they are transformed by a converter and subsequently processed in an unit for time measurement of mechanical oscillation propagation and for displaying of an actual angle displacement, ch a ra cte rize d by th at , that the magnetostrictive waveguide (1) is situated in a perimeter groove (71) formed in one of mutually rotating parts

(7), the perimeter groove (71) being advantageously filled with an insulating compound (8).

2. Magnetostrictive indicator according to the claim 1, c h ar a ct erize d by th at , that the beginning (11) and the end (12) of the magnetostrictive waveguide (1) overlap one another.

3. Magnetostrictive indicator according to the claim 1 or 2, ch a ra cte rize d by th at , that the magnetostrictive waveguide (1) is formed by a ferromagnetic magnetostrictive conductor (6) which is disposed in the insulating casing (5).

4. Magnetostrictive indicator according to the claim 1 or 2, ch a ra cte rize d by th at , that the magnetostrictive waveguide (1) consists of at least two segments (Ia, Ib).

5. Magnetostrictive indicator according to some of the previous claims, c h a r acte riz e d by t h at , that the beginnings (Ha, 1 Ib) of the segments (Ia, Ib) overlap one another, as well as the ends (12a, 12b) of the segments (Ia, Ib) overlap one another.

6. Magnetostrictive indicator according to some of the previous claims, c h a r acte riz e d by th at , that the magnetostrictive waveguide (1) is provided, on its beginning (11), with a sensing terminal (2) and on its end (12) with a reference terminal (3).

7. Magnetostrictive indicator according to some of the previous claims, c h a r acte riz e d by th at , that the sensing terminal (2) is formed by a casing (21) , in which the magnetostrictive waveguide (1) is fixed, its beginning (11) contacting the indicator (22) of mechanical oscillations, to which contacts (23) for the connection of converter (41) of the evaluating module (4) fit.

8. Magnetostrictive indicator according to some of the previous claims, c h a r acte riz e d by th at , that the reference terminal (3) is formed by a casing (31), in which the end (12) of the magnetostrictive waveguide (1) is fixed , by the side of which the reference magnet (32) in a casing (31) is fixed.

9. Magnetostrictive indicator according to some of the previous claims, c h a r acte riz e d by th at , that to the output of the converter (41) of the evaluating module (4), a correlation unit (42) is connected, to the output of which an unit (43) for the evaluating of the propagation time of mechanical oscillations and for displaying an actual angle displacement is connected.