EP1201934A2 - Unité cylindre-piston avec dispositif pour déterminer la position du piston - Google Patents

Unité cylindre-piston avec dispositif pour déterminer la position du piston Download PDF

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Publication number
EP1201934A2
EP1201934A2 EP01203962A EP01203962A EP1201934A2 EP 1201934 A2 EP1201934 A2 EP 1201934A2 EP 01203962 A EP01203962 A EP 01203962A EP 01203962 A EP01203962 A EP 01203962A EP 1201934 A2 EP1201934 A2 EP 1201934A2
Authority
EP
European Patent Office
Prior art keywords
cylinder
piston
unit
sensor
piston rod
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.)
Withdrawn
Application number
EP01203962A
Other languages
German (de)
English (en)
Other versions
EP1201934A3 (fr
Inventor
Claudio c/o Ognibene S.P.A. Ognibene
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.)
Ognibene SpA
Original Assignee
Ognibene SpA
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 Ognibene SpA filed Critical Ognibene SpA
Publication of EP1201934A2 publication Critical patent/EP1201934A2/fr
Publication of EP1201934A3 publication Critical patent/EP1201934A3/fr
Withdrawn legal-status Critical Current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
    • F15B15/2892—Means for indicating the position, e.g. end of stroke characterised by the attachment 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
    • F15B15/2861—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using magnetic means

Definitions

  • This invention relates generally to a device for measuring the position of the piston rod in a hydraulic cylinder.
  • An applicational sector in which the problem of measuring the axial position of the piston rod is particularly felt is that of steering cylinders for operation with hydrostatic guide units, where the position of the piston rod determines the position of the wheels.
  • inductive system in which a series of grooves or notches corresponding to a determined binary code is provided on the piston rod. Said grooves are then read by an inductive sensor positioned external to the cylinder.
  • This solution has proved not totally satisfactory, mainly because of problems of cost.
  • Another solution consists of providing on the piston rod a particular surface machining effect forming a sort of knurling which is read by an optical sensor. This solution presents problems of sealing between the cylinder and piston rod, and has proved unsuitable if the cylinder-piston unit is used in unfavourable environmental conditions.
  • the object of the present invention is to overcome the drawbacks of the known art within the framework of a simple, rational, reliable and low-cost solution.
  • the invention attains this object by providing a cylinder-piston unit provided with a device for measuring the axial position which the piston assumes within the cylinder, said piston being connected to the piston rod, at least one end of which emerges from said cylinder.
  • said measuring device comprises a fixed sensor element positioned outside the cylinder shell and able to sense the position of a movable element rigid with the piston.
  • the piston position has to be determined by more than one sensor to ensure detection of any individual fault in the measuring devices and to possibly enable the system to operate notwithstanding the fault.
  • said measuring system therefore comprises several fixed sensor elements associated with the cylinder in order to measuring the position of several movable sensor elements rigid with the piston.
  • said movable sensor element is a magnet
  • said fixed sensor element comprises a wave guide which is fixed onto the outer shell of the cylinder, and is connected to a transducer/sensor.
  • the movable sensor elements are magnets, whereas said fixed sensor elements each comprise a wave guide, which is inserted into a respective axial hole provided in the outer shell of the cylinder, and is connected to a respective transducer/sensor.
  • the signals sensed by the transducer/sensors are then fed to one or more control units which execute a series of predetermined operations on the basis of the axial position of the piston.
  • said movable sensors are magnets of annular shape inserted into a respective suitable circumferential seat in the piston.
  • the solution in which the at least one wave guide is located in at least one axial hole provided in the wall of the cylinder satisfies the precise functional requirement of minimizing the distance between the wave guide and the movable sensor, in order to free the apparatus from disturbances which could be created by extraneous magnetic fields, and also to maximize the magnetic signal picked up by the wave guide.
  • the preferential solution of locating at least one wave guide in at least one axial hole in the cylinder wall also satisfies the requirement of protecting the wave guide from damage.
  • the said wave guide location also satisfies precise cost requirements in that it avoids the cost of applying an outer protective tube to the cylinder.
  • the provision of holes in the wall for receiving the wave guide is virtually of zero cost, considering that the cylinders are produced by extrusion.
  • the cylinders obtained in this manner are also suitable for use with or without the invention.
  • the measuring device of the invention can be used in combination either with cylinder-piston units with a through piston rod or with cylinder-piston units in which only one end of the piston rod emerges from the cylinder.
  • Figure 1 is an axial section through the invention.
  • Figure 2 is the section II-II of Figure 1.
  • Figure 3 is a view from III of Figure 1.
  • Figure 4 is a partial view of Figure 1.
  • FIG. 1 shows the cylinder-piston unit 1, comprising a cylinder 2 containing a through piston rod 3.
  • the ends of the piston rod 3 emerge from two end caps 20 and 21 of the cylinder 2, suitable seal gaskets 200 being interposed therebetween.
  • a piston 4 which can slide sealedly within the cylinder 2.
  • the piston 4 divides the interior volume of the cylinder into two chambers 40 and 41, each of which is supplied with fluid via a conduit indicated by 400 and 410 respectively.
  • the piston 4 presents in its lateral surface three annular seats indicated by the reference numerals 5, 6, 7 respectively.
  • the central annular seat 6 houses a seal gasket 60
  • the annular seat 5 houses a guide shoe 50
  • the annular seat 7 houses a magnetic sensor element 9 of annular shape.
  • the sensor element 9 is a magnet forming part of the device for measuring the position of the piston with which the invention is provided.
  • said device comprises a fixed second sensor element 10, consisting of a wave guide 100 inserted into an axial hole 201 provided in the wall of the cylinder 2.
  • the wave guide 100 is connected to a transducer/sensor 102 connected in its turn to a control unit, not shown.
  • the purpose of said transducer/sensor 102 is both to generate current pulses and to sense voltage pulses.
  • the axial position of the piston 4 is measured by virtue of the interaction of two magnetic fields, one of which is generated by the sensor element 9 and the other by a current pulse which is induced in the wave guide 100 and flows through it.
  • the interaction of said magnetic fields produces in the wave guide 100 a mechanical torsion which propagates along the wave guide and is sensed by the transducer/sensor 102 fixed to one end of the wave guide 100.
  • the axial position of the piston 4 can be determined.
  • the transducer/sensor 102 feeds said pulse to the control unit, which executes a series of predetermined operations based on the axial position assumed by the piston 4 within the cylinder.
  • a typical applicational variant given by way of non-limiting example, comprises 3 fixed sensors and 2 movable sensor elements.

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)
  • Means For Warming Up And Starting Carburetors (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)
EP01203962A 2000-10-23 2001-10-16 Unité cylindre-piston avec dispositif pour déterminer la position du piston Withdrawn EP1201934A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITRE000100 2000-10-23
IT2000RE000100A IT1319435B1 (it) 2000-10-23 2000-10-23 Gruppo cilindro-pistone con dispositivo rilevatore della posizionedello stelo

Publications (2)

Publication Number Publication Date
EP1201934A2 true EP1201934A2 (fr) 2002-05-02
EP1201934A3 EP1201934A3 (fr) 2003-12-03

Family

ID=11453975

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01203962A Withdrawn EP1201934A3 (fr) 2000-10-23 2001-10-16 Unité cylindre-piston avec dispositif pour déterminer la position du piston

Country Status (2)

Country Link
EP (1) EP1201934A3 (fr)
IT (1) IT1319435B1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2473869C2 (ru) * 2007-01-29 2013-01-27 Испано Сюиза Устройство измерения положения поршня в цилиндре, узел, содержащий цилиндр, поршень и такое устройство, и авиационный двигатель, содержащий такой узел
RU199474U1 (ru) * 2020-04-24 2020-09-02 Общество с ограниченной ответственностью "Уральский инжиниринговый центр" Гидравлический цилиндр двустороннего действия с гидростатическими направляющими
RU218232U1 (ru) * 2022-12-08 2023-05-17 Общество с ограниченной ответственностью "Уральский инжиниринговый центр" Гидравлический цилиндр двустороннего действия с гидростатическими направляющими

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63238415A (ja) * 1987-03-26 1988-10-04 Hitachi Constr Mach Co Ltd シリンダ装置のストロ−ク検出装置
WO1993014371A1 (fr) * 1992-01-13 1993-07-22 Caterpillar Inc. Appareil de detection de la position d'un piston dans un cylindre
DE4334811A1 (de) * 1993-10-13 1995-04-20 Festo Kg Positionserfassungsvorrichtung an einem Linearantrieb
US5717330A (en) * 1996-03-07 1998-02-10 Moreau; Terence J. Magnetostrictive linear displacement transducer utilizing axial strain pulses

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2473869C2 (ru) * 2007-01-29 2013-01-27 Испано Сюиза Устройство измерения положения поршня в цилиндре, узел, содержащий цилиндр, поршень и такое устройство, и авиационный двигатель, содержащий такой узел
RU199474U1 (ru) * 2020-04-24 2020-09-02 Общество с ограниченной ответственностью "Уральский инжиниринговый центр" Гидравлический цилиндр двустороннего действия с гидростатическими направляющими
RU218232U1 (ru) * 2022-12-08 2023-05-17 Общество с ограниченной ответственностью "Уральский инжиниринговый центр" Гидравлический цилиндр двустороннего действия с гидростатическими направляющими

Also Published As

Publication number Publication date
EP1201934A3 (fr) 2003-12-03
ITRE20000100A0 (it) 2000-10-23
ITRE20000100A1 (it) 2002-04-23
IT1319435B1 (it) 2003-10-10

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