EP0051603A1 - Selecteur serie-parallele pour la direction et l'outil. - Google Patents

Selecteur serie-parallele pour la direction et l'outil.

Info

Publication number
EP0051603A1
EP0051603A1 EP81900682A EP81900682A EP0051603A1 EP 0051603 A1 EP0051603 A1 EP 0051603A1 EP 81900682 A EP81900682 A EP 81900682A EP 81900682 A EP81900682 A EP 81900682A EP 0051603 A1 EP0051603 A1 EP 0051603A1
Authority
EP
European Patent Office
Prior art keywords
circuit
flow
flow path
pressure
source
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
EP81900682A
Other languages
German (de)
English (en)
Other versions
EP0051603A4 (fr
EP0051603B1 (fr
Inventor
Larry W Lorimor
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.)
Caterpillar Inc
Original Assignee
Caterpillar Tractor Co
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 Caterpillar Tractor Co filed Critical Caterpillar Tractor Co
Publication of EP0051603A1 publication Critical patent/EP0051603A1/fr
Publication of EP0051603A4 publication Critical patent/EP0051603A4/fr
Application granted granted Critical
Publication of EP0051603B1 publication Critical patent/EP0051603B1/fr
Expired legal-status Critical Current

Links

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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F15B2211/3053—In combination with a pressure compensating valve
    • F15B2211/30535—In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and directional control valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/351—Flow control by regulating means in feed line, i.e. meter-in control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6055—Load sensing circuits having valve means between output member and the load sensing circuit using pressure relief valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/78—Control of multiple output members
    • F15B2211/781—Control of multiple output members one or more output members having priority

Definitions

  • This invention relates to a hydraulic control system for supplying pressurized fluid to two work circuits, one of which has priority over the other.
  • the steering motor In many vehicles which have a hydraulic steering motor and a hydraulic implement circuit which receive flow from a single pump, the steering motor is connected upstream of and in series relation with the implement system. As a. result, the pump is working against the sum of the load pressures of the steering motor and the implement circuits. The pump, however, can only operate up to its rated operating pressure and can only supply its maximum rated flow rate. Hence, if the implement circuit is experiencing a high load pressure, only a relatively low pressure (a portion .of the pump rated operating pressure) is available across the steering motor for operating it. This can lead to low torque stalling of the steering motor.
  • Prior art load sensitive hydraulic systems suffer from the disadvantage that the return flow from the priority work circuit is passed to tank regardless of the pressure requirements of subsequent circuits. This requires the use of a wastefully large pump.
  • the present invention is directed to overcome one or more of the problems set forth above.
  • an improvement is provided in a hydraulic system having a pressurized fluid source, a first work circuit having an output flow, a second work circuit, an input flow path connected to deliver flow of pressurized fluid from the source to the first circuit, and a series flow path connected to receive the output flow from the first circuit and to deliver the output flow to the second circuit.
  • the improvement comprises a parallel flow path connected to receive a portion of the flow from the source and to deliver it to the second circuit.
  • a valving structure is in the series flow path and means are provided for opening the valving structure to direct flow to the second circuit in response to load pressure in the second circuit being below a selected value. The valving structure blocks flow to the second circuit when the load pressure in the
  • OMPI second circuit is above that value.
  • motor discharge flow is supplied via series flow to the low pressure implement hydraulic f nctions, which thereby provides high speed cornering of the vehicle carrying the system and high speed implement correction at relatively lower pressures. Further, discharge from the vehicle steering motor is dumped to tank when implement pressures are high. The system thereby prevents low torque motor stall due to insufficient differential pressure across the steering motor. Also, the system provides underspeed-type engine protection whereby utilization of vehicle horsepower is enhanced.
  • the drawing consists of a single figure which schematically illustrates an embodiment of the present invention.
  • the drawing illustrates a hydraulic control system 10.
  • the system 10 includes a pressurized fluid source or pump 12.
  • the pump 12 supplies fluid to a first work circuit 14 of primary (higher) priority and to a second work circuit 16 of secondary (lower) priority.
  • the first work circuit 14 includes a motor 18, for example, a steering motor.
  • the second work circuit 16 also includes a motor, for example, a hydraulic cylinder 20, which would typically serve for operating an implement of a vehicle, for example, for controlling the position of a dozer blade, or for controlling any of a number of other implements carried by a vehicle.
  • An input flow path 22 is connected to receive pressurized fluid from the pump 12 and to deliver it to the first work circuit 14 in a manner which will shortly become apparent.
  • a series flow path 24 is connected to receive an output flow from the first work circuit 14 and to deliver the output flow to the second circuit 16.
  • a parallel flow path 26 is provided which is connected to receive a portion of the flow from the pump 12 and to deliver that portion to the second circuit 16.
  • the parallel flow path 26 communicates with the input flow path 22 via a modulating priority valve 28.
  • Priority valve 28 modulates between being in the position shown in the drawing wherein flow from;path 22 is directed through priority valve 28 to the first work circuit 14 and being shifted leftwardly in the drawing, wherein the input flow path 22 connects to the parallel flow path 26 via an appropriate passage 30 defined by the priority valve 28.
  • the portion of flow through passage 30 of the modulating priority valve 28 can be varied from zero flow up to the entire output of the pump 12 as will be described below.
  • the priority valve 28 delivers flow to a conduit 34 and thereby to a steering valve 36.
  • Priority valve 28 also serves as means 32 for blocking a part (fraction) of the flow through the parallel flow path 26 in response to a predetermined pressure differential being established across the steering valve 36 (in the embodiment shown, a pilot controlled steering valve) .
  • the steering valve 36 controls the speed and direction of operation of the motor 18.
  • the pressure differential is established by a spring 31. For a given displacement of steering valve 36, the pump flow increases until the pressure differential (line 38 minus line 33) exceeds the force of spring 31, causing the priority valve 28 to move leftwardly opening parallel flow path 26.
  • the pressure * in parallel flow path 26 rises toward, for example, 200 psi, to dump over an unloading valve -39 which is spring loaded with a force equivalent to 200 psi.
  • the pump 12 then destrokes to satisfy steering requirements. If circuit 16 requires flow, the parallel and/or series flow paths 24 and 26 supply flow as the pump 12 increases flow trying to build up, for example, 200 psi, above load.
  • a valving structure 42 is provided in the series flow path 24.
  • the valving structure 42 serves as a series-parallel selector valve having an open position to direct flow from the series flow path 24 to the second circuit 16 and a closed position to block flow from the series flow path 24 to the second circuit 16.
  • Means 44 are provided for opening the valving structure 42 in response to system pressure in the second circuit 16 being below a selected value and for closing the valving structure 42 in response to system pressure in the second circuit 16 being above that selected value. While hydraulic means 44 are shown in the drawing, equivalent electronic means, including pressure sensors and solenoid operated valves, may be substituted for the illustrated hydraulic means 44.
  • a pressure representative of the pressure in a flow path 45 is delivered via a line 46 to a first end 48 of the valving structure 42.
  • the pressure in the flow path 45 is the same as that in the parallel flow path 26 and is determined by the pressure in the second work circuit 16, whenever an implement control valve 50 is shifted either leftwardly or rightwardly from the center position shown in the drawing or by the unloading valve 39 connected to flow path 45.
  • the pressure in line 46 which opens valving structure 42 is determined by the load pressure in the second work circuit 16.
  • the valving structure 42 When the pressure in the second work circuit 16 is below the aforementioned selected value, the valving structure 42 is in the position shown in the drawing. In that position, the series flow path 24 connects with the parallel flow path 26 at a junction, 52, from which the flow path 45 proceeds to the implement control valve 50.
  • the valving structure 42 When load pressure in the second work circuit 16, and thereby pressure in the line 46, is above the selected value, the valving structure 42 is shifted upwardly from the position shown in the drawing, thereby dumping flow from the series flow path 24 to a tank 54. This prevents series connection of the circuits 14.and 16 when the second work circuit 16 is working at high pressure. Hence, sufficient flow, at needed working pressure, is provided at all times to the steering motor 18.
  • One of the advantages of the present invention is, thus, that the pump 12 can be sized to primarily provide the steering function, although the pump 12 can be sized slightly larger so as to provide
  • the pump 12 is preferably of the variable displacement type wherein the rate of fluid flow from the pump 12 can be controlled as needed.
  • means 56 are provided for controlling the rate of fluid flow from the pump 12, in response to the greater of the load * pressures in the first circuit 14 and the second circuit 16. That is, whichever of the load pressures is greater, whether it be in the first circuit 14 or in the second circuit 16, that pressure is delivered via a line 58 to a conventional pump displacement control 60 which controls the pump 12 to provide the needed flow at the pressure needed to satisfy the load requirements up to some predetermined level.
  • the load pressure from the first circuit 14 is resolved in steering valve 36 and delivered to a line 64.
  • the load pressure in the second work circuit 16 is resolved in valve 50 and delivered to a line 68.
  • the load pressures from the lines 64 and 68 are introduced to a resolver 70 which resolves the greater of these pressures into the line 58 for delivery to the pump displacement control 60.
  • steering valve 36 illustrated is of the pilot controlled variety, being controlled by a pilot control valve 72, it is clear that the invention is not so limited in that a manually controlled steering valve can be used in place of the pilot controlled valve 36.
  • the present invention is particularly useful with earth working equipment such as dozers and the like.
  • the primary priority circuit is the circuit which powers the steering of the dozer and the secondary priority circuit is a hydraulic cylinder which controls an implement.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

Les systemes hydrauliques de charge du type interrompu en serie de l'art anterieur etaient incapables d'assurer a la fois simultanement la direction du vehicule a pleine vitesse dans les virages et la correction de l'outil tout en les empechant lorsque les outils fonctionnent a haute pression, tout en empechant le calage du moteur a bas couple. A cet effet, une conduite d'entree (22) envoie du fluide sous pression depuis une source (12) vers un premier circuit (de direction) prioritaire (14). Une conduite d'ecoulement en serie (24) envoie le debit de sortie provenant des circuits (14) vers un circuit de l'outil (16). Une conduite d'ecoulement en parallele (26) envoie une partie du debit provenant de la source (12) vers le circuit d'outil (16). Une structure a soupape (42) est montee dans la conduite d'ecoulement en serie (24). La structure a soupape (42) est ouverte en reponse a la pression de charge dans le circuit d'outil (16) lorsque cette pression est egale ou inferieure a une valeur selectionnee et est fermee en reponse a la pression de charge dans le circuit d'outil lorsque cette pression de charge est superieure a cette valeur selectionnee. En general, l'ecoulement par la canalisation d'ecoulement en parallele (26) est bloque lorsque la pression differentielle dans le circuit de direction (14) est inferieure a une valeur specifique. La conduite en virage a haute vitesse et la correction d'outil sont assurees a des faibles pressions et sont empechees lorsque l'outil fonctionne a haute pression. On empeche le moteur de caler lorsque le couple est bas. L'utilisation de la puissance du vehicule est amelioree avec les reseaux de circuit en serie/parallele selectionnables.
EP19810900682 1980-05-16 1980-05-16 Selecteur serie-parallele pour la direction et l'outil Expired EP0051603B1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1980/000577 WO1981003364A1 (fr) 1980-05-16 1980-05-16 Selecteur serie-parallele pour la direction et l'outil

Publications (3)

Publication Number Publication Date
EP0051603A1 true EP0051603A1 (fr) 1982-05-19
EP0051603A4 EP0051603A4 (fr) 1983-04-06
EP0051603B1 EP0051603B1 (fr) 1986-03-19

Family

ID=22154347

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810900682 Expired EP0051603B1 (fr) 1980-05-16 1980-05-16 Selecteur serie-parallele pour la direction et l'outil

Country Status (4)

Country Link
EP (1) EP0051603B1 (fr)
JP (1) JPS57500601A (fr)
DE (1) DE3071511D1 (fr)
WO (1) WO1981003364A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481770A (en) * 1982-03-22 1984-11-13 Caterpillar Tractor Co. Fluid system with flow compensated torque control
JP2830525B2 (ja) * 1991-07-08 1998-12-02 日産自動車株式会社 流体作動系のポンプ容量制御装置
FR2754571B1 (fr) * 1996-10-16 1998-12-24 Rexroth Sigma Dispositif de distribution hydraulique multiple
JP2003097510A (ja) * 2001-09-27 2003-04-03 Toshihito Okamoto 油圧作業機械用増設油圧回路

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1516814A (fr) * 1966-11-18 1968-02-05 Ckd Praha Narodni Podnik Dispositif pour la commande de la vitesse d'un mécanisme de rotation automatique, en particulier pour grues et excavateurs à mécanisme d'entraînement hydraulique
GB1111637A (en) * 1966-03-05 1968-05-01 Danfoss As Hydraulic circuit for hydrostatic steering devices
DE2159766A1 (de) * 1971-12-02 1973-06-07 Rexroth Gmbh G L Druckregelung mit verstellpumpe
US3960284A (en) * 1972-10-02 1976-06-01 American Hoist & Derrick Company Hydraulic backhoe circuitry

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE24892E (en) * 1956-11-23 1960-10-25 Flow divider valve with relief valve and variable orifice
US3073123A (en) * 1961-09-27 1963-01-15 New York Air Brake Co Hydraulic system
US3641879A (en) * 1970-04-16 1972-02-15 Gen Motors Corp Central hydraulic system for a vehicle
US4043419A (en) * 1976-06-04 1977-08-23 Eaton Corporation Load sensing power steering system
US4089169A (en) * 1976-08-19 1978-05-16 The Scott & Fetzer Company Pressure actuated signal fluid control for load responsive systems

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1111637A (en) * 1966-03-05 1968-05-01 Danfoss As Hydraulic circuit for hydrostatic steering devices
FR1516814A (fr) * 1966-11-18 1968-02-05 Ckd Praha Narodni Podnik Dispositif pour la commande de la vitesse d'un mécanisme de rotation automatique, en particulier pour grues et excavateurs à mécanisme d'entraînement hydraulique
DE2159766A1 (de) * 1971-12-02 1973-06-07 Rexroth Gmbh G L Druckregelung mit verstellpumpe
US3960284A (en) * 1972-10-02 1976-06-01 American Hoist & Derrick Company Hydraulic backhoe circuitry

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8103364A1 *

Also Published As

Publication number Publication date
EP0051603A4 (fr) 1983-04-06
EP0051603B1 (fr) 1986-03-19
JPS57500601A (fr) 1982-04-08
WO1981003364A1 (fr) 1981-11-26
DE3071511D1 (en) 1986-04-24

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