EP0618373B1 - Indicateur de position - Google Patents

Indicateur de position Download PDF

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Publication number
EP0618373B1
EP0618373B1 EP19940200818 EP94200818A EP0618373B1 EP 0618373 B1 EP0618373 B1 EP 0618373B1 EP 19940200818 EP19940200818 EP 19940200818 EP 94200818 A EP94200818 A EP 94200818A EP 0618373 B1 EP0618373 B1 EP 0618373B1
Authority
EP
European Patent Office
Prior art keywords
profiling
piston rod
sensors
magnetic field
circuit
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.)
Revoked
Application number
EP19940200818
Other languages
German (de)
English (en)
Other versions
EP0618373A1 (fr
Inventor
Ymker Lefert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hydraudyne Cylinders BV
Original Assignee
Hydraudyne Cylinders BV
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
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Application filed by Hydraudyne Cylinders BV filed Critical Hydraudyne Cylinders BV
Publication of EP0618373A1 publication Critical patent/EP0618373A1/fr
Application granted granted Critical
Publication of EP0618373B1 publication Critical patent/EP0618373B1/fr
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/28—Means for indicating the position, e.g. end of stroke
    • F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
    • F15B15/2861—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using magnetic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/28—Means for indicating the position, e.g. end of stroke
    • F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
    • F15B15/2846—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using detection of markings, e.g. markings on the piston rod

Definitions

  • the invention relates to a device for determining the position of a metal piston rod in relation to a chosen reference point.
  • the invention relates to an apparatus for determining the position of a piston rod relative to a reference point, in which the circumference surface of the piston rod comprises a substantially tangentially directed profiling with a pattern repeating itself in the axial direction, comprising a magnetic member which has been fixed relative to the reference point for generating a magnetic field which is affected by the profiling, at least two sensors fixed relative to the reference point for sensing the strength of the magnetic field, and a processing circuit for processing the signals generated by the sensors, in which the sensors have a mutual distance in the axial direction, which equals an integer multiple of the pitch of the profiling plus or minus a quarter of the pitch.
  • the means for generating a magnetic field comprise coils, located concentrically relative to the piston rod. Consequently these coils generate a magnetic field, which extends substantially axially relative to the piston rod. Axial displacement of the piston rod will lead to a change in the position of the profiling. However, this change will have a minimal effect on the actual part of the magnetic field. Further, this change is only measurable in a limited extend due to the also axial position of the measuring coils. Expressed differently, the coupling between the generating coil and the measuring coil is only affected in a limited way by the positioning of the piston rod. Consequently the sensibility and the resolution of this known apparatus are limited.
  • the aim of the invention is to provide such a position sensing apparatus, in which a greater sensitivity and a greater resolution are possible.
  • magnetoresistive sensors allows a greater freedom in the determination of the direction of the magnetic field, so that is can be directed such, that the sensors are subject to a greater change in the strength of the magnetic field, when the position of the piston rod is changed.
  • the magnetic field can be directed tangentially or radially relative to the piston rod. In both cases the magnetic field at the circumference of the piston rod will be strongly affected by the position of the profiling. Further, such a direction of the magnetic field allows a greater freedom in the position of the magnet for generating the magnetic field.
  • the profiling comprises ridges and grooves and the ridges and the grooves have the same width.
  • Figure 1 shows a metal piston rod 1 provided with a longitudinal surface profiling 2 of tangentially and successively arranged grooves and which is enveloped with an electrically non-conducting cover layer 3.
  • a cylinder 4 with a sensor 6 fixed in the cylinder head 5 serves to determine the position of piston rod 1.
  • Sensor 6 is situated between the piston rod 1 and means 7 for correctly positioning a magnetic field.
  • the figure further shows means 8 for adapting and processing the changes in the magnetic field converted by sensor 6 into electrical signals.
  • the sensor 6 comprises essentially two bridge circuits 9, 10 respectively, each being composed of two magnetoresistive elements 11, 12, 13, 14 respectively and two normal resistors 15, 16, 17, 18 respectively. Both bridge circuits have been positioned such, that the distance between the centre of both bridge circuits is equal to an integer multiple of the pitch of the profiling to plus or minus a quarter of the pitch. In the present case the distance is 13 ⁇ 4 times the pitch. As consequence of this feature it is ensured, that always one of the sensors is in a transient part of the substantially sinusoidal magnetic field, so that the resolution is as large as possible.
  • the edges of the profiling are chamfered. This causes an aproximate sinusoidal effect on the magnetic field generated by the magnet by the profiling, which is an advantage in the processing of the signals thus generated.
  • Both bridge circuits 9, 10 respectively are supplied by a generator 19.
  • the generator 19 generates a sinusoidal signal with a frequency of several tenths of kHz.
  • the phase of both signals to be supplied to the bridge circuits 9, 10 is equal.
  • the signals coming from the bridge circuits 9, 10 respectively are fed an amplifier circuit 21, 22 respectively, being integrated in the sensor 6. Further, they are supplied to a processing circuit 8 through a common cable 23.
  • the sine generators 19, 20 can be present in the sensor 6, but that they can also be incorporated into the processing circuit 8.
  • the magnetoresistive elements 11-14 together with the resistors 15-18 and the amplifier circuits 21, 22 are incorporated into the sensor 6. It is however, also possible to provide the magnetoresistive elements 11-14 in the sensor 6. It is also possible, departing from the depicted situation, to integrate the processing circuit 24-35 into the sensor.
  • the processing circuit 8 comprises a circuit 24 for generating a signal representing an angle ⁇ .
  • the output signal is supplied to a sine signal generator 25, the cosine signal generator 26 respectively.
  • the output signal of the circuit 25 is a sine function of the an angle ⁇ representing signal
  • the output signal of the cosine circuit 26 is a signal representing the cosine of the angle ⁇ .
  • the output signal of the circuit 25 is supplied to a comparator circuit 27, together with the output signal of the circuit 21, and the output signal of the signal 26 is together with the output of the circuit 22 supplied to a comparator circuit 28. It is noted, that the output signal of the circuit 21 varies cosine shaped as a function of the replacement of the piston rod, whereas the output signal of the circuit 22 varies as a sine shaped signal of said relocation.
  • both comparator circuits 27, 28 are added, taking the signs of said signals into account in an adding circuit 29 and are supplied to control circuit 30. It is remarked, that both output signals of the circuit 27, 28 respectively, can be expressed as, A . cos ( x p . 2 ⁇ ) sin ⁇ t . sin ⁇ or respectively A . sin ( x p . 2 ⁇ ) sin ⁇ t . cos ⁇
  • the circuit uses the property by having the control circuit 30 generating a control signal which is supplied to the angle ⁇ generator 24 through an intergrating circuit 31, in which the control signal is determined such by the control loop, that the above mentioned condition is satisfied.
  • the output signal of the angle ⁇ generator is an indication for the position of the piston rod 1.
  • This output signal is in analoge format available on the output signal 32, and is also in digital format available on an output signal 34 through an A/D converter 33.
  • the circuit comprises an output 35, for the control circuit 30, on which an output signal in the format of a speed signal is available.
  • the output signal of the angle ⁇ generator in binary format is converted into incremental counting pulses after an adjustable resolution coding circuit 32 by means of pulse shapers 33.
  • these pulses are available on output circuit 34.
  • these pulses are added in a bi-directional binary counter 36, and the counting value is available in binary format on the output circuit 34.
  • the binary counting value is converted into a Gray-format, after which this information is available on the output circuit 34.
  • the already mentioned second embodiment is supplied with a D/A converter 38, after the position information in analoge format is available on the output 39.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Actuator (AREA)

Claims (6)

  1. Dispositif permettant de déterminer la position d'une tige de piston (1) par rapport à un point de référence, dans lequel la surface circonférentielle de la tige de piston (1) comprend un profilage (2) dirigé de manière sensiblement tangentielle avec un motif se répétant dans le sens axial, comprenant un élément magnétique (7) qui est fixe par rapport au point de référence pour générer un champ magnétique qui est affecté par le profilage (2), au moins deux capteurs (9, 10) fixes par rapport au point de référence pour détecter la force du champ magnétique, et un circuit de traitement (8) pour traiter les signaux générés par les capteurs (9, 10), dans lequel les capteurs (9, 10) sont séparés par une distance mutuelle dans le sens axial, qui est égale à un multiple entier du pas du profilage (2) plus ou moins un quart du pas, caractérisé en ce que
    l'élément magnétique (7) est prévu pour générer un champ magnétique s'étendant de manière sensiblement tangentielle ou radiale;
    les capteurs (9, 10) comprennent chacun un élément magnétorésistif (11-18) intégré dans un circuit en pont (9, 10);
    le profilage (2) est chanfreiné; et
    le profilage (2) est recouvert d'une couche continue (3) en une seule pièce d'un matériau céramique qui est lisse sur sa surface extérieure et qui est adjacent à et s'insère sur le profilage (2) de la tige de piston (1) et dont les propriétés magnétiques sont différentes de celles de la tige de piston (1).
  2. Dispositif selon la revendication 1, caractérisé en ce que le profilage (2) comprend des arêtes et des gorges et en ce que les arêtes et les gorges présentent la même largeur.
  3. Dispositif selon la revendication 1 ou 2, caractérisé en ce que les circuits en ponts (9,10) sont connectés chacun à une source de tension de courant alternatif (19, 20) et en ce que les phases des signaux générés par chacune des sources de tension de courant alternatif (19, 20) présentent une différence de pi/2.
  4. Dispositif selon la revendication 3, caractérisé en ce que le circuit de traitement (8) est prévu pour comparer les signaux de sortie de chacun des circuits en ponts (9, 10) avec, respectivement, un cosinus et un sinus du signal représentant un angle qui est fonction de cette comparaison.
  5. Dispositif selon la revendication 4, caractérisé en ce que le circuit de traitement (8) est prévu pour générer un signal incrémental numérique.
  6. Dispositif selon la revendication 4 ou 5, caractérisé en ce que le circuit de traitement (8) est prévu pour générer un signal numérique et un signal analogique, représentant chacun la position de la tige de piston (1).
EP19940200818 1993-03-30 1994-03-28 Indicateur de position Revoked EP0618373B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL9300565A NL9300565A (nl) 1993-03-30 1993-03-30 Positie-indicator.
NL9300565 1993-03-30

Publications (2)

Publication Number Publication Date
EP0618373A1 EP0618373A1 (fr) 1994-10-05
EP0618373B1 true EP0618373B1 (fr) 1999-09-01

Family

ID=19862234

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19940200818 Revoked EP0618373B1 (fr) 1993-03-30 1994-03-28 Indicateur de position

Country Status (3)

Country Link
EP (1) EP0618373B1 (fr)
DE (1) DE69420299T2 (fr)
NL (1) NL9300565A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10119941A1 (de) * 2001-04-23 2002-10-24 Mannesmann Rexroth Ag Druckmittelzylinder mit einem Meßsystem zur Bestimmung der Absolutposition der Kolbenstange bezüglich eines Bezugspunkts
DE102014212382A1 (de) 2014-06-27 2015-12-31 Robert Bosch Gmbh Verfahren zur Fertigung eines Bauteils mit einem Wegmesssystem

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19939497C2 (de) * 1999-08-20 2001-09-27 Samson Ag Antrieb eines Stellventils mit Sensiereinheit zur Ventilpositionserfassung
US7116097B2 (en) * 2004-10-27 2006-10-03 Deere & Company System and method for detecting the axial position of a shaft or a member attached thereto
DE102006010780A1 (de) 2006-03-08 2007-09-13 Liebherr-France Sas Positionsmeßsystem für Hydraulikzylinder
US8058867B2 (en) 2008-08-18 2011-11-15 Deere & Company System for determining the position of a movable member
CN102011763A (zh) * 2010-06-05 2011-04-13 常州液压成套设备厂有限公司 用于驱动自安装采油平台升降的液压缸

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3956973A (en) * 1972-07-11 1976-05-18 Basic Aluminum Castings Company Die casting machine with piston positioning control
DE2855681A1 (de) * 1978-12-21 1980-06-26 Kracht Pumpen Motoren Mit einem fluid zu betreibender antriebszylinder
DE3241525A1 (de) * 1982-11-10 1984-05-10 Wabco Westinghouse Steuerungstechnik GmbH & Co, 3000 Hannover Einrichtung zum erfassen der position oder/und der geschwindigkeit des kolbens eines arbeitszylinders
JPS59117902A (ja) * 1982-12-23 1984-07-07 S G:Kk 流体圧シリンダの位置決め制御装置
JPS601514A (ja) * 1983-06-17 1985-01-07 Copal Co Ltd 変位量検出器

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10119941A1 (de) * 2001-04-23 2002-10-24 Mannesmann Rexroth Ag Druckmittelzylinder mit einem Meßsystem zur Bestimmung der Absolutposition der Kolbenstange bezüglich eines Bezugspunkts
WO2002086330A1 (fr) 2001-04-23 2002-10-31 Bosch Rexroth Ag Cylindre de pression comprenant un systeme de mesure pour determiner la position absolue d'une tige de piston par rapport a un point de reference
DE102014212382A1 (de) 2014-06-27 2015-12-31 Robert Bosch Gmbh Verfahren zur Fertigung eines Bauteils mit einem Wegmesssystem

Also Published As

Publication number Publication date
EP0618373A1 (fr) 1994-10-05
DE69420299D1 (de) 1999-10-07
DE69420299T2 (de) 1999-12-30
NL9300565A (nl) 1994-10-17

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