EP0713818B1 - Système hydraulique de contrÔle de force - Google Patents

Système hydraulique de contrÔle de force Download PDF

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Publication number
EP0713818B1
EP0713818B1 EP95118465A EP95118465A EP0713818B1 EP 0713818 B1 EP0713818 B1 EP 0713818B1 EP 95118465 A EP95118465 A EP 95118465A EP 95118465 A EP95118465 A EP 95118465A EP 0713818 B1 EP0713818 B1 EP 0713818B1
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EP
European Patent Office
Prior art keywords
force
signal
cylinder
hydraulic system
hydraulic
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.)
Expired - Lifetime
Application number
EP95118465A
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German (de)
English (en)
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EP0713818A1 (fr
Inventor
Gualtiero Balossini
Piero Bozzola
Giovanni Jacazio
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Microtecnica SRL
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Microtecnica SRL
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61F—RAIL VEHICLE SUSPENSIONS, e.g. UNDERFRAMES, BOGIES OR ARRANGEMENTS OF WHEEL AXLES; RAIL VEHICLES FOR USE ON TRACKS OF DIFFERENT WIDTH; PREVENTING DERAILING OF RAIL VEHICLES; WHEEL GUARDS, OBSTRUCTION REMOVERS OR THE LIKE FOR RAIL VEHICLES
    • B61F5/00—Constructional details of bogies; Connections between bogies and vehicle underframes; Arrangements or devices for adjusting or allowing self-adjustment of wheel axles or bogies when rounding curves
    • B61F5/02—Arrangements permitting limited transverse relative movements between vehicle underframe or bolster and bogie; Connections between underframes and bogies
    • B61F5/22—Guiding of the vehicle underframes with respect to the bogies
    • B61F5/24—Means for damping or minimising the canting, skewing, pitching, or plunging movements of the underframes
    • B61F5/245—Means for damping or minimising the canting, skewing, pitching, or plunging movements of the underframes by active damping, i.e. with means to vary the damping characteristics in accordance with track or vehicle induced reactions, especially in high speed mode

Definitions

  • the present invention relates to a hydraulic force regulating system.
  • Such a system may be applied to advantage to the active lateral suspensions of railroad cars, to which reference is made herein to give a clear idea of the problem underlying the present invention.
  • FIG. 1 shows a schematic view of a railroad car 1 presenting a truck 2, a body 3, and lateral suspensions 4.
  • the suspensions of most currently operated trains substantially comprise a system of fairly elastic springs and dampers for absorbing shock and preventing stress from being transferred to the body.
  • Such a solution fails to operate correctly when cornering, in which case, the centrifugal force produced shifts the body as far as the limit stops where the suspensions are fully deformed and therefore no longer capable of absorbing lateral stress.
  • pneumatic active suspensions each of which comprises a pneumatic cylinder connected to a supply tank by valves controlled by an electronic regulating unit.
  • the lateral stress on the truck is absorbed by the flexibility of the suspension itself, while the force generated on the body when cornering is compensated by the regulating system.
  • an accelerometer measures the centripetal acceleration of one truck on the train (e.g. that of the engine) correlated to the centrifugal force, and an electronic control unit so controls supply to the pneumatic cylinders as to generate a force in opposition to the centrifugal force.
  • a hydraulic system has therefore been proposed, which, by virtue of its intrinsic characteristics (rapid response and precision), provides for a more accurate cornering acceleration correction, and for more rapidly and accurately recentering the body in relation to the truck. Moreover, as compared with pneumatic systems, hydraulic systems are more suitable for generating large forces, and are more lightweight and compact.
  • Hydraulic systems however, present a poor degree of flexibility, so that they fail to provide for absorbing rapid stress such as the shock generated on the trucks of railroad cars.
  • hydraulic regulating systems are normally used for generating large forces, and when a rapid, precise variation in the regulated force is required.
  • the possibility of safely employing high pressures provides for reducing component weight and size, while the low elasticity of the hydraulic fluid provides for a rapid variation in pressure and hence in the regulated force.
  • the latter property (low elasticity of the hydraulic fluid), however, represents a drawback when regulating a force in the presence of rapid movement of the mechanical member on which the force is exerted, which movement results in an undesired variation in pressure and hence in the regulated force.
  • a force regulating system comprising a hydraulic actuator including a cylinder housing a piston movable in relation to the cylinder to generate an actual force; a hydraulic circuit supplying said hydraulic cylinder and in turn comprising a control element for controlling supply to the cylinder; and a force regulating loop in turn comprising a measuring unit for measuring said actual force, a differential unit receiving an actual force signal from said measuring unit and a nominal force signal, and generating an error signal, and a regulator receiving said error signal and generating a first control signal for controlling said control element; characterized in that it comprises a speed measuring device for measuring the speed of said piston in relation to said cylinder; and compensating means for generating an additional control signal for said control element on the basis of said speed, and in such a manner as to achieve a substantially elastic performance of said hydraulic system.
  • the present invention provides for a regulation which, on the basis of the measured speed of the mechanical element on which the regulated force is exerted, varies the regulating signals so as to eliminate, at each instant, any variation in force produced by the movement of the mechanical element.
  • the regulation according to the present invention provides for rendering a conventional hydraulic system "artificially" flexible.
  • the hydraulic system 10 in Figure 2 comprises a linear actuator 11 connected by a servovalve 12 to a supply conduit 13 and a return conduit 14.
  • Actuator 11 comprises a cylinder 15, and a piston 16 movable inside cylinder 15 and connected to a translating mechanical member 18 (in the case of the railroad car in Figure 1, translating member 18 may comprise truck 2, and cylinder 15 may be fixed to body 3).
  • a conduit 20 with a calibrated orifice 21 connects the two chambers 15a, 15b of cylinder 15; and servovalve 12 regulates the supply of pressurized fluid to and from chambers 15a, 15b on the basis of the sign and amplitude of input current I.
  • System 10 also comprises two pressure transducers 22a, 22b connected to and for measuring the pressure in respective chambers 15a, 15b, and which are connected by respective leads 23a, 23b to an electronic regulating unit 25 comprising:
  • electronic unit 25 receives the required force signal F r (in the example shown of a railroad car, the force required to eliminate the centrifugal force when cornering, and determined, as stated, by means of a processing unit or a table reading) and the signal F m indicating the actual force generated by actuator 11.
  • F r the required force signal
  • F m the signal required to eliminate the centrifugal force when cornering
  • unit 25 On the basis of error E, and using a known regulating principle (e.g. a PID regulator), unit 25 generates a control current signal which is amplified to supply current I to servovalve 12.
  • conduit 20 and calibrated orifice 21 provide for reducing the pressure gain of servovalve 12, which is too high for certain types of application (such as the railroad car in the example shown), and for consequently improving the stability of system 10.
  • System 10 may be provided with other performance-improving components (not shown), e.g. for reducing offset and leakage on the servovalve, and achieving a given performance in the event of a breakdown.
  • system 10 provides for regulating the force accurately and rapidly.
  • a frequency response with a passband up to about 10 Hz, and hence a predominant time constant of 15-20 ms.
  • mechanical member 18 is moving at high (constant or variable) speed, even serious errors in the value of the force applied may arise, depending on the operating conditions involved.
  • hydraulic system 10 is made “artificially” flexible, to permit regulation even in the presence of stress due to the movement of translating member 18.
  • Figure 3 shows a more detailed view of the structure of servovalve 12, and more specifically the structure of slide valve 30 of the servovalve.
  • slide valve 30 For the Figure 3 circuit to achieve a force F in the direction shown (rightwards), slide valve 30 must be moved leftwards in relation to the center position, to permit the passage of a certain amount of fluid from supply line 13 to left chamber 15a, and at the same time permit the passage of the same amount of fluid from right chamber 15b to return line 14.
  • the numerator term AV/G Q constitutes a disturbance which generates an error in the pressure difference and hence in the regulated force; and, since area A of the piston is selected according to the available pressure and the maximum force to be generated, a large flow gain G Q , i.e. a large servovalve, is required to reduce the pressure error produced by the speed of the piston. That is, all other conditions being equal, the larger the servovalve is, the smaller is the error produced by the speed of the piston. For each application, however, there is a limit to the maximum size permissible of the servovalve.
  • FIG. 4 shows a regulating system 10' which, as compared with the known system 10 in Figure 2, also comprises a further regulating loop 35 within regulating unit 25'.
  • Loop 35 in turn comprises a compensating stage 36 supplied with a speed signal V generated by a transducer 37 associated with piston 16; and stage 36 generates a correction current I 1 which is supplied to an adding node 38 by which it is added to the current I generated by regulator 29 to supply a total regulated current I 2 to servovalve 12.
  • multiplication correction factor K A/G Q may be constant and selected according to the average value of G Q , or may vary by following the variations in flow gain with p 1 and p 2 (e.g. using a prememorized table, as shown symbolically by arrow 40 in Figure 4).
  • system according to the present invention may be applied to advantage to the active lateral suspension of a railroad car, to ensure recentering when cornering, by generating a force in opposition to the centrifugal force produced, and also to absorb any shock on the truck capable of producing rapid displacement of the piston, by rendering the system "artificially" elastic as described above.
  • the power unit for generating the current supplied to the servovalve may be separated from regulator 29 and compensating unit 37 and located downstream from adding node 38, in which case, regulator 29 and compensating unit 37 generate respective electronic control signals which are added in node 38 and subsequently amplified.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Servomotors (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Vehicle Body Suspensions (AREA)

Claims (8)

  1. Dispositif de régulation d'effort hydraulique (10') comprenant un actionneur hydraulique (11) comportant un cylindre (15) contenant un piston (16) mobile par rapport au cylindre (15) afin de produire un effort réel; un circuit hydraulique (12 à 14) alimentant ledit cylindre et comprenant lui-même un élément de commande (12) destiné à commander l'alimentation vers le cylindre; et une boucle de régulation d'effort comprenant elle-même une unité de mesure (22a, 22b, 26, 27) afin de mesurer ledit effort réel, une unité différentielle (28) recevant un signal d'effort réel (Fm), provenant de ladite unité de mesure, et un signal d'effort nominal (Fr) et produisant un signal d'erreur (E), et un régulateur (29) recevant ledit signal d'erreur et produisant un premier signal de commande (I) afin de commander ledit élément de commande (12); caractérisé en ce que la boucle de régulation d'effort comprend un dispositif de mesure de vitesse (37) destiné à mesurer la vitesse (V) dudit piston (16) par rapport audit cylindre (15); et un moyen de compensation (36) destiné à produire un signal de commande supplémentaire (I1) pour ledit élément de commande (12) en fonction de ladite vitesse, et de manière à obtenir un fonctionnement sensiblement élastique dudit dispositif hydraulique (10').
  2. Dispositif hydraulique selon la revendication 1, caractérisé en ce que ledit moyen de compensation (36) comprend un élément de multiplication destiné à multiplier un signal de vitesse (V), produit par ledit dispositif de mesure de vitesse (37), par un facteur proportionnel (K).
  3. Dispositif hydraulique selon la revendication 2, caractérisé en ce que ledit facteur proportionnel (K) est égal à A/GQ, où A représente la surface dudit piston (16), et GQ le gain en débit dudit élément de commande (12).
  4. Dispositif hydraulique selon la revendication 3, caractérisé en ce que ledit facteur proportionnel (K) est constant.
  5. Dispositif hydraulique selon la revendication 3, caractérisé en ce que ledit facteur proportionnel (K) est variable, et dépend de la différence de pression (Δp) dans ledit cylindre (15) dudit actionneur (11).
  6. Dispositif hydraulique selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend un élément d'addition (38) recevant ledit premier signal de commande (I) et ledit signal de commande supplémentaire (I1), et produisant un signal cumulé (I2) qui est délivré audit élément de commande (12).
  7. Dispositif de commande selon l'une quelconque des revendications précédentes, caractérisé en ce que ledit élément de commande comprend une vanne asservie (12).
  8. Dispositif de commande selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il constitue une suspension latérale active (4) d'un véhicule ferroviaire (1).
EP95118465A 1994-11-25 1995-11-23 Système hydraulique de contrÔle de force Expired - Lifetime EP0713818B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO940957 1994-11-25
IT94TO000957A IT1267627B1 (it) 1994-11-25 1994-11-25 Sistema idraulico di regolazione di una forza.

Publications (2)

Publication Number Publication Date
EP0713818A1 EP0713818A1 (fr) 1996-05-29
EP0713818B1 true EP0713818B1 (fr) 1999-04-07

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP95118465A Expired - Lifetime EP0713818B1 (fr) 1994-11-25 1995-11-23 Système hydraulique de contrÔle de force

Country Status (4)

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EP (1) EP0713818B1 (fr)
DE (1) DE69508888T2 (fr)
ES (1) ES2131746T3 (fr)
IT (1) IT1267627B1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6679565B2 (en) * 2001-10-26 2004-01-20 Delphi Technologies, Inc. Gain scheduling for controlled force application
ITMI20032379A1 (it) * 2003-12-04 2005-06-05 Isocomp S P A Dispositivo di smorzamento dinamico semiattivo elettroidraulico perfezionato per mezzi di locomozione.
US8079310B2 (en) * 2009-11-25 2011-12-20 LTK Consulting Services, Inc. Vertical position compensating device for a vehicle
DE102017002926A1 (de) 2017-03-27 2018-09-27 Liebherr-Transportation Systems Gmbh & Co. Kg Aktuator zum Steuern eines Radsatzes eines Schienenfahrzeugs

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2689475A1 (fr) * 1992-04-01 1993-10-08 Faiveley Transport Suspension transversale pour véhicule ferroviaire.
AT408975B (de) * 1992-10-08 2002-04-25 Siemens Sgp Verkehrstech Gmbh Anordnung zur regelung einer querfederung zwischen drehgestell und wagenkasten eines schienenfahrzeuges
DE4234535A1 (de) * 1992-10-14 1994-04-21 Abb Henschel Waggon Union Laufwerk für Schienenfahrzeuge

Also Published As

Publication number Publication date
ES2131746T3 (es) 1999-08-01
EP0713818A1 (fr) 1996-05-29
DE69508888T2 (de) 1999-09-09
ITTO940957A1 (it) 1996-05-25
DE69508888D1 (de) 1999-05-12
ITTO940957A0 (it) 1994-11-25
IT1267627B1 (it) 1997-02-07

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