EP0105473B1 - Hydraulic circuit with two variable flow pumps controlled by excess flow - Google Patents

Hydraulic circuit with two variable flow pumps controlled by excess flow Download PDF

Info

Publication number
EP0105473B1
EP0105473B1 EP83109740A EP83109740A EP0105473B1 EP 0105473 B1 EP0105473 B1 EP 0105473B1 EP 83109740 A EP83109740 A EP 83109740A EP 83109740 A EP83109740 A EP 83109740A EP 0105473 B1 EP0105473 B1 EP 0105473B1
Authority
EP
European Patent Office
Prior art keywords
valve
control
pressure
variable displacement
line
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
Application number
EP83109740A
Other languages
German (de)
French (fr)
Other versions
EP0105473A3 (en
EP0105473A2 (en
Inventor
Raymond Joseph Lobmeyer
James Anton Miller
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.)
Deere and Co
Original Assignee
Deere and 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 Deere and Co filed Critical Deere and Co
Publication of EP0105473A2 publication Critical patent/EP0105473A2/en
Publication of EP0105473A3 publication Critical patent/EP0105473A3/en
Application granted granted Critical
Publication of EP0105473B1 publication Critical patent/EP0105473B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2246—Control of prime movers, e.g. depending on the hydraulic load of work tools
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with two or more pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • 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
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • 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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • 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
    • F15B2211/25—Pressure control functions
    • 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
    • F15B2211/30505—Non-return valves, i.e. check 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
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • 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
    • F15B2211/65—Methods of control of the load sensing 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups
    • 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

Definitions

  • the invention relates to a hydraulic system with two variable displacement pumps, each of which feeds a group of control valves with excess outlet, wherein a pressure medium can be fed from one system to the other.
  • Such a hydraulic system known for example from US-A-4024710, has two hydraulic pumps with variable delivery quantities (variable displacement pumps), the displacement of which is automatically controlled as a function of the requirements of several hydraulic functions, represented by excess oil flows which are determined for the various functions Control valves originate.
  • spool valves with an open center position are mostly used for function control for excess valves.
  • the control spools are closed in the middle position and block the oil flow coming from the pump, resulting in an increase in pressure.
  • the oil flow is divided between the open center position and the work outlets, with the oil flow being directed through the open center position into the excess outlet while the oil return is returned to the reservoir.
  • Current sharing of this type makes it difficult for an operator to control the speed of a function to be performed since changes in the functional load must be compensated for by shifting the slide valve.
  • variable displacement hydraulic pumps that are automatically controlled to meet the fast demands of the system.
  • An example of a system with a variable displacement pump controlled in this way is disclosed in the aforementioned US-A-3,465,519.
  • This previously known system comprises a single variable pump, a multiplicity of functions to be carried out, for which control valves are provided, in which the excess flow of the last control valve is passed to a pressure-dependent displacement control in order to reduce the pump delivery rate as a function of the increasing excess current.
  • This system avoids connecting functions of the same priority in parallel to a common oil supply or, in situations where a second pump is required, supplying the maximum amount of oil that the functions could require.
  • the invention has for its object to add the excess flow of the second variable displacement pump to the flow of the first variable displacement pump when the pressure of the excess flow of the control valve originating from the second variable displacement pump is greater than the pressure of the excess flow of the control valve originating from the first variable displacement pump.
  • this object is achieved in that the first inlet of a pressure selection valve to the excess outlet of a privileged control valve fed by the second variable displacement pump, the second inlet of the pressure selection valve to the excess outlet of a downstream control valve fed by the first variable displacement pump, and to the pressure-dependent displacement control of the first
  • the variable displacement pump and the outlet of the pressure selection valve are connected to the pressure-dependent adjustment control of the second adjustment pump, that the pressure selection valve transmits the lower of the two inlet pressures to the adjustment control of the second adjustment pump, and that a bypass is provided with a bypass line which is the first inlet of the pressure selection valve connects to the inlet of the preferential control valve fed by the first variable displacement pump and has a one-way valve which prevents a flow of flow in the direction of the pressure selection valve.
  • FIG. 1 an exemplary embodiment of the invention is shown.
  • the drawing shows schematically a hydraulic control system for an excavator.
  • the hydraulic system as a whole is designated by the reference number 10 and comprises a plurality of control valves which are pressure-compensated, have an excess outlet and correspond essentially to the embodiment according to US-A-3718159, with the exception that some control valves only comprise a function control part which is provided with a supply part is plugged together, while the patented embodiment control parts open for three functions beard that are plugged together with a supply part.
  • the control system 10 comprises a support foot control valve 12, a control valve 14 for pivoting the cabin, and a right and a left travel control valve 16, 18, all of which are shown in a simplified representation as a block.
  • the support foot control valve 12 comprises a supply part 20 which is connected to a main boom, a bucket boom and a bucket control part 22, 24 and 26.
  • the supply part 20 has an inlet 28 and an excess outlet 30 and encloses an unillustrated pressure-compensated flow control valve, which divides the oil flow entering the inlet between the excess outlet and an outlet leading to the function control part in accordance with the arrangement of corresponding control slide valves in the control parts and the like Need a function to be controlled.
  • the main boom, bucket boom, and bucket control parts each have a pair of outlet ports 32, 34, 36, each for connecting the opposite ends of double-acting hydraulic cylinders.
  • the control valve 14 for pivoting the cabin has a supply part 38 which is plugged together with a swivel control part 40 and approximately corresponds to the supply part 20 of the control valve 12, that is to say also has an inlet 42 and an excess outlet 44.
  • the swing control part 40 includes a pair of outlet ports 45 for connecting the opposite outputs of a reversible swing motor.
  • the right and left travel control valves 16, 18 are of identical design and each include a supply part 46 and 48 and travel control valves 50, 52.
  • the supply parts 46, 48 have inlets 54, 56 and excess outlets 58, 60.
  • the travel control valves 50, 52 each include a pair of outlet ports 62, 64 to which the opposite ports of a reversible right and left travel motor can be connected.
  • a first and a second hydraulic pump 66, 68 with a variable delivery rate (variable pump) are used to apply oil to the control valves, which are each connected to a pressure-dependent adjustment control 70, 72, which increase the delivery rate of the pumps as a function of pressure drop signals.
  • variable displacement pump 66 is connected with its inlet to a pump sump 74 and with its outlet to the inlet 28 of the supply part 20 of the support foot control valve 12 via a flow line 76.
  • a first excess line 78 is connected at one end to the excess outlet 30 of the supply part 20 and at the other forked end to the inlet connections 54, 56 of the travel control valves 16, 18.
  • the excess outlets 58, 60 of the two travel control valves 16, 18 are connected via a second and a third excess line 80, 82 to the first inlet 84 and the second inlet 86 of a pressure selection valve 88, respectively.
  • the latter has an outlet 90 which is connected to the two inlets 84, 86 via a central valve bore 92.
  • a first and a second shut-off ball 94, 96 are arranged on both sides of the connection for the outlet 90 and act together with a first and second valve seat 98, 100 to prevent oil flow from the inlets 84, 86 to the outlet 90.
  • a reciprocating plunger 102 is arranged between the two shut-off balls 94, 96, which is longer than the distance between the two valve seats mentioned, so that only one of the two shut-off balls abuts against the valve seat assigned to them at the same time can (see also Figure 3 of US-A-3 863 449).
  • each pressure increase in the excess lines 80, 82 causes one of the two shut-off balls 94, 96 to be pressed against its valve seat and thereby to lift the other shut-off ball from its valve seat, so that a pressure drop in the lines 80, 82 is transmitted to the outlet 90 .
  • the latter is connected via a control line 104 to the pressure-dependent adjustment control 70 of the adjustment pump 66.
  • the pump 68 is connected with its inlet to a pump sump 74 and with its outlet via a flow line 106 to the inlet 42 of the control valve 14.
  • a fourth excess line 108 connects the excess outlet 44 to a first inlet 110 of a pressure selection valve 112, which is identical in construction to the pressure selection valve 88 described above.
  • the pressure selection valve 112 is connected to the control line 104 with its second inlet 114 and to the control line 104 with its outlet 116 pressure-dependent adjustment control 72 of the adjustment pump 68 is connected, specifically via a control line 118.
  • a central valve bore 120 connects the connections 110, 114 and 116.
  • first and second shut-off balls 122, 124 are provided, that cooperate with first and second valve seats 126 and 128. Between the shut-off balls 122, 124, a plunger 130 is slidably arranged back and forth in the valve bore 120, the length of which is dimensioned in such a way that the shut-off balls do not lie against their valve seats at the same time.
  • the pressure selection valve 112 therefore connects the respectively lower pressure, which exists in the control line 104 or the fourth excess line 108, to the control line 118 and thereby to the adjustment control 72 of the adjustment pump 68.
  • a bypass circuit comprises a bypass line 132 which is connected between the fourth excess line 108 and the flow line 76 and has a one-way valve 134 which only allows the oil flow in the direction from line 108 to line 76.
  • pressure selection valve 112 prevents oil flow from line 108 to the control line 118; the pressure in line 108 then opens valve 134 and thereby connects excess line 108 to flow line 76, so that the delivery volume generated by pump 68 is added to pump 66.
  • a pair of line compensators 136, 138 are provided in the circuit leading to the valve 12 or leading away from this valve.
  • the latter each include stepped cylindrical chambers 140, 142, of which the chamber 140 is connected to the flow line 76 with a small end via a line 144, while the chamber 142 is connected with a small end to the first excess line 78 via a line 146.
  • Both chambers 140, 142 are each connected with their large ends to one another and to the control line 104 via a forked line 148.
  • a small and a large piston 150 and 152 which are connected to one another via a piston rod 154, are displaceably arranged in the small and large sections of the chamber 140.
  • a pair of centering springs 156, 158 are provided which press the piston 152 into a central position in the large section of the chamber 140.
  • the chamber 142 also has a small and a large piston 160, 162, which are arranged such that they can be moved back and forth and are connected to one another via a piston rod 164.
  • a pair of centering springs 166, 168 are provided on the opposite sides of the large piston 162.
  • the excess current in the excess line 78 will decrease and thus reduce the pressure acting on the small piston 160 of the line compensator 138.
  • the piston 160 is then shifted to the left due to the unbalanced forces resulting from an increase in volume in the end of the large section of the chamber 142, which leads to a decrease in pressure in the bifurcated line 148 and, in turn, a pressure drop in the control line 104 .
  • the adjustment control 70 of the adjustment pump 66 will react to this pressure drop by increasing the pump delivery rate.
  • a solenoid actuated pressure relief valve 172 which has its inlet 174 connected to the flow line 76 via a portion of the bypass line 132 downstream of the one-way valve 134.
  • the pressure relief valve 172 is more commonly decayed Position shown in which it prevents a flow connection between the line 132 and the control line 104.
  • the pressure-limiting valve 172 is expediently actuated as a function of the drop in the output speed of the excavator drive motor to a predetermined minimum. Any known speed measurement circuit for said output speed can be used to energize the solenoid of the pressure relief valve 172 when the engine speed drops below a predetermined minimum.
  • the pressure relief valve 172 provides the connection to the line 132 and thus to the outlet of the pump 66 and the oil flow flowing through the one-way valve 134 into the control line 104.
  • the pressure in the adjustment control 70 is increased, which in turn reduces the delivery rate of the pump 66, which in turn takes a partial load on the drive motor and thereby prevents its drop in speed.
  • the control valves 12, 14, 16 and 18 divide the existing oil flow between the function performed in each case and the excess outlet of the valve. For example, the portion of the oil flow arriving at the support foot control valve 12, which is not required for the function, is passed on to the right and left travel control valves 16, 18 via the excess line 78. The proportion of this oil flow arriving at the control valves 16, 18, which is not required to actuate the driving functions, is passed on to the excess lines 80, 82.
  • the pressure selection valve 88 then operates as a function of the pressure increase in the lines 80, 82 in order to pass on pressure drops in the lines 80, 82 to the control line 104 and thus to the adjustment control 70 of the adjustment pump 66.
  • the adjustment control 70 operates in dependence on the pressure prevailing in the control line 104 in order to bring about a pump adjustment which only leads to a slightly larger amount of oil delivered by the pump 66, that is to say it is necessary to actuate the support foot and / or driving functions.
  • the pressure selection valve 112 operates depending on the liquid pressure in the control line 104 and in the over shot line 108 to connect the respectively lower pressure with the control line 118 and thereby with the adjusting device 72 of the variable pump 68. If the pressure in line 108 is greater than in line 132, the one-way valve 134 opens and thereby connects the oil flow of the excess line 108 to the oil quantity delivered by the variable pump 66. As a result, the pump 68 can temporarily support the pump 66 in supplying the support leg and driving functions with unusually high amounts of oil. As a result, the pump 66 manages with a smaller adjustment than would otherwise be the case.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
  • Lifting Devices For Agricultural Implements (AREA)

Description

Die Erfindung betrifft ein Hydrauliksystem mit zwei Verstellpumpen, die jeweils eine Gruppe von Steuerventilen mit Überschussauslass speisen, wobei eine Einspeisung von Druckmitteln aus dem einen System in das andere möglich ist.The invention relates to a hydraulic system with two variable displacement pumps, each of which feeds a group of control valves with excess outlet, wherein a pressure medium can be fed from one system to the other.

Ein derartiges, beispielsweise aus der US-A-4024710 bekanntes Hydrauliksystem weist zwei Hydraulikpumpen mit veränderlicher Fördermenge (Verstellpumpen) auf, deren Verstellung automatisch gesteuert wird in Abhängigkeit von den Erfordernissen mehrerer Hydraulikfunktionen, dargestellt durch Überschuss-Ölströme, die von für die verschiedenen Funktionen bestimmten Steuerventilen herrühren.Such a hydraulic system, known for example from US-A-4024710, has two hydraulic pumps with variable delivery quantities (variable displacement pumps), the displacement of which is automatically controlled as a function of the requirements of several hydraulic functions, represented by excess oil flows which are determined for the various functions Control valves originate.

Überschuss steht als typische Option bei den meisten Ventilen zur Verfügung, die in offenen oder geschlossenen Hydrauliksystemen Verwendung finden. Wird eine Vielzahl von Steuerventilen in Serie geschaltet, gibt diese Option dem ersten Steuerventil Priorität hinsichtlich des zur Verfügung stehenden Ölstromes, der dann, wenn er nicht benötigt wird, aus dem Überschussauslass dem nächsten Ventil zugeleitet wird, anstatt ihn in den Ölbehälter zurückzuführen, wie es bei üblichen offenen Hydrauliksystemen der Fall ist.Excess is a typical option available on most valves used in open or closed hydraulic systems. If a large number of control valves are connected in series, this option gives priority to the first control valve with regard to the available oil flow, which when it is not required is fed from the excess outlet to the next valve instead of returning it to the oil tank as it is is the case with conventional open hydraulic systems.

In offenen Hydrauliksystemen werden für Überschussventile meist Steuerschieber mit offener Mittelstellung zur Funktionsteuerung verwendet. Die Steuerschieber werden in der Mittelstellung geschlossen und blockieren so den von der Pumpe kommenden Ölfluss, so dass sich ein Druckanstieg ergibt. Der Ölstrom wird geteilt zwischen der offenen Mittelstellung und den Arbeitsauslässen, wobei der Ölstrom durch die offene Mittelstellung in den Überschussauslass geleitet wird, während der Ölrückfluss zum Behälter zurückgeleitet wird. Eine Stromteilung dieser Art macht es für eine Bedienungsperson schwierig, die Geschwindigkeit einer auszuübenden Funktion zu steuern, da Änderungen in der Funktionsbelastung durch Verschiebung des Schieberventils kompensiert werden müssen.In open hydraulic systems, spool valves with an open center position are mostly used for function control for excess valves. The control spools are closed in the middle position and block the oil flow coming from the pump, resulting in an increase in pressure. The oil flow is divided between the open center position and the work outlets, with the oil flow being directed through the open center position into the excess outlet while the oil return is returned to the reservoir. Current sharing of this type makes it difficult for an operator to control the speed of a function to be performed since changes in the functional load must be compensated for by shifting the slide valve.

Dieses Steuerproblem lässt sich etwas verringern durch Verwendung eines Spezialventils mit offener Mittelstellung und Überschussauslass, das einen Strömungsregelschieber umfasst, der als Stromteiler arbeitet in Abhängigkeit vom Ölbedarf einer vom Ventil gesteuerten Funktionsaus- übung. Der Ölstrom ist abhängig von der Verschiebung des Steuerschiebers, wobei der Ölstrom für sich ändernde Lasten konstant gehalten und auch auf einen vorbestimmten Anteil begrenzt wird. Beispiele für druckkompensierte Ventile mit offener Mittelstellung und Überschussauslass lassen sich den US-Patentschriften Nr. 3 455 210 (entspricht DE-C-1650 375), 3465519 (entspricht DE-B-1751 934) und 3718159 (entspricht DE-A-2201 839) entnehmen.This control problem can be reduced somewhat by using a special valve with an open center position and excess outlet, which includes a flow control slide that works as a flow divider depending on the oil requirement of a function controlled by the valve. The oil flow is dependent on the displacement of the control spool, the oil flow being kept constant for changing loads and also being limited to a predetermined proportion. Examples of pressure-compensated valves with an open center position and excess outlet can be found in US Pat. Nos. 3,455,210 (corresponds to DE-C-1650 375), 3465519 (corresponds to DE-B-1751 934) and 3718159 (corresponds to DE-A-2201 839 ) remove.

Aus Gründen der Effizienz werden in Hydrauliksystemen mit Ventilen mit offener Mittelstellung Hydraulikpumpen mit veränderlicher Fördermenge verwendet, die automatisch gesteuert werden, um den schnellen Anforderungen des Systems gerecht zu werden. Ein Beispiel für ein System mit einer in dieser Weise gesteuerten Verstellpumpe ist in der vorstehend erwähnten US-A-3 465 519 offenbart. Dieses vorbekannte System umfasst eine einzige Verstellpumpe, eine Vielzahl von auszuübenden Funktionen, für die Steuerventile vorgesehen sind, bei denen der Überschussstrom des letzten Steuerventils zu einer druckabhängigen Verstellsteuerung geleitet wird, um die Pumpenfördermenge in Abhängigkeit des zunehmenden Überschussstromes zu vermindern. Bei diesem System verzichtet man darauf, Funktionen gleicher Priorität in Parallelschaltung an eine gemeinsame Ölzufuhr anzuschliessen, oder aber bei Situationen, in denen eine zweite Pumpe erforderlich ist, die höchstmögliche Ölmenge zuzuführen, die die Funktionen benötigen könnten.For efficiency reasons, hydraulic systems with open center valves use variable displacement hydraulic pumps that are automatically controlled to meet the fast demands of the system. An example of a system with a variable displacement pump controlled in this way is disclosed in the aforementioned US-A-3,465,519. This previously known system comprises a single variable pump, a multiplicity of functions to be carried out, for which control valves are provided, in which the excess flow of the last control valve is passed to a pressure-dependent displacement control in order to reduce the pump delivery rate as a function of the increasing excess current. This system avoids connecting functions of the same priority in parallel to a common oil supply or, in situations where a second pump is required, supplying the maximum amount of oil that the functions could require.

Der Erfindung liegt die Aufgabe zugrunde, den Überschussstrom der zweiten Verstellpumpe dem Förderstrom der ersten Verstellpumpe zuzufügen, wenn der Druck des von der zweiten Verstellpumpe herrührenden Überschussstromes des Steuerventils grösser ist als der Druck des von der ersten Verstellpumpe herrührenden Überschussstromes des Steuerventils.The invention has for its object to add the excess flow of the second variable displacement pump to the flow of the first variable displacement pump when the pressure of the excess flow of the control valve originating from the second variable displacement pump is greater than the pressure of the excess flow of the control valve originating from the first variable displacement pump.

Diese Aufgabe wird gemäss der Erfindung dadurch gelöst, dass der erste Einlass eines Druckauswahlventils an den Überschussauslass eines von der zweiten Verstellpumpe gespeisten bevorrechtigten Steuerventils, der zweite Einlass des Druckauswahlventils an den Überschussauslass eines von der ersten Verstellpumpe gespeisten nachgeordneten Steuerventils sowie an die druckabhängige Verstellsteuerung der ersten Verstellpumpe und der Auslass des Druckauswahlventils an die druckabhängige Verstellsteuerung der zweiten Verstellpumpe angeschlossen sind, dass das Druckauswahlventil den niedrigeren der beiden Eingangsdrücke an die Verstellsteuerung der zweiten Verstellpumpe übermittelt, und dass ein Bypass mit einer Bypass-Leitung vorgesehen ist, die den ersten Einlass des Druckauswahlventils mit dem Einlass des von der ersten Verstellpumpe gespeisten bevorrechtigten Steuerventils verbindet und ein Einwegventil aufweist, das einen Strömungsfluss in Richtung des Druckauswahlventils verhindert.According to the invention, this object is achieved in that the first inlet of a pressure selection valve to the excess outlet of a privileged control valve fed by the second variable displacement pump, the second inlet of the pressure selection valve to the excess outlet of a downstream control valve fed by the first variable displacement pump, and to the pressure-dependent displacement control of the first The variable displacement pump and the outlet of the pressure selection valve are connected to the pressure-dependent adjustment control of the second adjustment pump, that the pressure selection valve transmits the lower of the two inlet pressures to the adjustment control of the second adjustment pump, and that a bypass is provided with a bypass line which is the first inlet of the pressure selection valve connects to the inlet of the preferential control valve fed by the first variable displacement pump and has a one-way valve which prevents a flow of flow in the direction of the pressure selection valve.

Weitere Merkmale und Vorteile der Erfindung sind Gegenstand der Unteransprüche und werden anhand eines Ausführungsbeispieles erläutert.Further features and advantages of the invention are the subject of the dependent claims and are explained using an exemplary embodiment.

In der Zeichnung ist eine als Beispiel dienende Ausführungsform der Erfindung dargestellt. Die Zeichnung zeigt schematisch ein hydraulisches Steuersystem für einen Bagger.In the drawing, an exemplary embodiment of the invention is shown. The drawing shows schematically a hydraulic control system for an excavator.

Das Hydrauliksystem insgesamt ist mit dem Bezugszeichen 10 bezeichnet und umfasst mehrere Steuerventile, die druckkompensiert sind, einen Überschussauslass aufweisen und im wesentlichen der Ausführungsform gemäss der US-A-3718159 entsprechen mit der Ausnahme, dass einige Steuerventile nur einen Funktionssteuerteil umfassen, der mit einem Versorgungsteil zusammengesteckt ist, während die patentierte Ausführungsform Steuerteile für drei Funktionen offenbart, die mit einem Versorgungsteil zusammengesteckt sind.The hydraulic system as a whole is designated by the reference number 10 and comprises a plurality of control valves which are pressure-compensated, have an excess outlet and correspond essentially to the embodiment according to US-A-3718159, with the exception that some control valves only comprise a function control part which is provided with a supply part is plugged together, while the patented embodiment control parts open for three functions beard that are plugged together with a supply part.

Das Steuersystem 10 umfasst ein Stützfuss-Steuerventil 12, ein Steuerventil 14 zum Verschwenken der Kabine sowie ein rechtes und ein linkes Fahr-Steuerventil 16, 18, die in vereinfachter Darstellung alle als Block dargestellt sind.The control system 10 comprises a support foot control valve 12, a control valve 14 for pivoting the cabin, and a right and a left travel control valve 16, 18, all of which are shown in a simplified representation as a block.

Das Stützfuss-Steuerventil 12 umfasst ein Versorgungsteil 20, das mit einem Hauptausleger-, einem Kübelausleger- und einem Kübel-Steuerteil 22, 24 und 26 zusammengesteckt ist. Das Versorgungsteil 20 weist einen Einlass 28 und einen Überschussauslass 30 auf und umschliesst ein nicht dargestelltes druckkompensiertes Stromsteuerventil, das den in den Einlass eintretenden Ölstrom zwischen dem Überschussauslass und einem zu dem Funktionssteuerteil führenden Auslass aufteilt in Übereinstimmung mit der Anordnung entsprechender Steuerschieberventile in den Steuerteilen und dem Bedarf einer zu steuernden Funktion. Die Hauptausleger-, Kübelausleger- und Kübel-Steuerteile weisen jeweils ein Paar Auslassanschlüsse 32, 34, 36 auf, die jeweils zum Anschluss der entgegengesetzten Enden doppelt wirkender Hydraulikzylinder dienen.The support foot control valve 12 comprises a supply part 20 which is connected to a main boom, a bucket boom and a bucket control part 22, 24 and 26. The supply part 20 has an inlet 28 and an excess outlet 30 and encloses an unillustrated pressure-compensated flow control valve, which divides the oil flow entering the inlet between the excess outlet and an outlet leading to the function control part in accordance with the arrangement of corresponding control slide valves in the control parts and the like Need a function to be controlled. The main boom, bucket boom, and bucket control parts each have a pair of outlet ports 32, 34, 36, each for connecting the opposite ends of double-acting hydraulic cylinders.

Das Steuerventil 14 zum Verschwenken der Kabine weist ein Versorgungsteil 38 auf, das mit einem Schwenk-Steuerteil 40 zusammengesteckt ist und etwa dem Versorgungsteil 20 des Steuerventils 12 entspricht, also ebenfalls einen Einlass 42 sowie einen Überschussauslass 44 aufweist. Das Schwenk-Steuerteil 40 umfasst ein Paar Auslassanschlüsse 45 zum Anschluss der entgegengesetzten Ausgänge eines reversiblen Schwingmotors.The control valve 14 for pivoting the cabin has a supply part 38 which is plugged together with a swivel control part 40 and approximately corresponds to the supply part 20 of the control valve 12, that is to say also has an inlet 42 and an excess outlet 44. The swing control part 40 includes a pair of outlet ports 45 for connecting the opposite outputs of a reversible swing motor.

Das rechte und linke Fahr-Steuerventil 16, 18 sind identisch ausgebildet und umfassen jeweils ein Versorgungsteil 46 und 48 sowie Fahr-Steuerventile 50, 52. Die Versorgungsteile 46, 48 weisen Einlässe 54, 56 und Überschussauslässe 58, 60 auf. Die Fahr-Steuerventile 50, 52 umfassen jeweils ein Paar Auslassanschlüsse 62, 64, an die die entgegengesetzten Anschlüsse eines reversiblen rechten und linken Fahrmotors angeschlossen werden können.The right and left travel control valves 16, 18 are of identical design and each include a supply part 46 and 48 and travel control valves 50, 52. The supply parts 46, 48 have inlets 54, 56 and excess outlets 58, 60. The travel control valves 50, 52 each include a pair of outlet ports 62, 64 to which the opposite ports of a reversible right and left travel motor can be connected.

Zur Beaufschlagung der Steuerventile mit Öl dienen eine erste und eine zweite Hydraulikpumpe 66, 68 mit veränderlicher Fördermenge (Verstellpumpe), die mit jeweils einer druckabhängigen Verstellsteuerung 70, 72 verbunden sind, die in Abhängigkeit von Druckabfallsignalen die Fördermenge der Pumpen erhöhen.A first and a second hydraulic pump 66, 68 with a variable delivery rate (variable pump) are used to apply oil to the control valves, which are each connected to a pressure-dependent adjustment control 70, 72, which increase the delivery rate of the pumps as a function of pressure drop signals.

Die Verstellpumpe 66 ist mit ihrem Einlass an einen Pumpensumpf 74 und mit ihrem Auslass an den Einlass 28 des Versorgungsteils 20 des Stützfuss-Steuerventils 12 über eine Vorlaufleitung 76 angeschlossen. Eine erste Überschussleitung 78 ist mit ihrem einen Ende an dem Überschussauslass 30 des Versorgungsteils 20 und mit ihrem anderen gegabelten Ende an die Einlassanschlüsse 54, 56 der Fahr-Steuerventile 16, 18 angeschlossen. Die Überschussauslässe 58, 60 der beiden Fahr-Steuerventile 16, 18 sind über eine zweite und eine dritte Überschussleitung 80, 82 an den ersten Einlass 84 bzw. den zweiten Einlass 86 eines Druckauswahlventils 88 angeschlossen. Letzteres weist einen Auslass 90 auf, der mit den beiden Einlässen 84, 86 über eine zentrale Ventilbohrung 92 in Verbindung steht. In letzterer sind eine erste und eine zweite Absperrkugel 94, 96 beidseitig des Anschlusses für den Auslass 90 angeordnet und wirken zusammen mit einem ersten und zweiten Ventilsitz 98, 100, um einen Ölstrom von den Einlässen 84, 86 zum Auslass 90 zu verhindern. In der Ventilbohrung 92 ist ein hin und her beweglicher Stössel 102 zwischen den beiden Absperrkugeln 94, 96 angeordnet, der länger ist als der Abstand zwischen den beiden genannten Ventilsitzen, so dass jeweils nur eine der beiden Absperrkugeln zur gleichen Zeit an dem ihr zugeordneten Ventilsitz anliegen kann (siehe auch Figur 3 der US-A-3 863 449). Daher führt jeder Druckanstieg in den Überschussleitungen 80, 82 dazu, eine der beiden Absperrkugeln 94, 96 gegen ihren Ventilsitz zu drücken und dadurch die andere Absperrkugel von ihrem Ventilsitz abzuheben, so dass ein Druckabfall in den Leitungen 80, 82 an den Auslass 90 übermittelt wird. Letzterer ist über eine Steuerleitung 104 an die druckabhängige Verstellsteuerung 70 der Verstellpumpe 66 angeschlossen.The variable displacement pump 66 is connected with its inlet to a pump sump 74 and with its outlet to the inlet 28 of the supply part 20 of the support foot control valve 12 via a flow line 76. A first excess line 78 is connected at one end to the excess outlet 30 of the supply part 20 and at the other forked end to the inlet connections 54, 56 of the travel control valves 16, 18. The excess outlets 58, 60 of the two travel control valves 16, 18 are connected via a second and a third excess line 80, 82 to the first inlet 84 and the second inlet 86 of a pressure selection valve 88, respectively. The latter has an outlet 90 which is connected to the two inlets 84, 86 via a central valve bore 92. In the latter, a first and a second shut-off ball 94, 96 are arranged on both sides of the connection for the outlet 90 and act together with a first and second valve seat 98, 100 to prevent oil flow from the inlets 84, 86 to the outlet 90. In the valve bore 92, a reciprocating plunger 102 is arranged between the two shut-off balls 94, 96, which is longer than the distance between the two valve seats mentioned, so that only one of the two shut-off balls abuts against the valve seat assigned to them at the same time can (see also Figure 3 of US-A-3 863 449). Therefore, each pressure increase in the excess lines 80, 82 causes one of the two shut-off balls 94, 96 to be pressed against its valve seat and thereby to lift the other shut-off ball from its valve seat, so that a pressure drop in the lines 80, 82 is transmitted to the outlet 90 . The latter is connected via a control line 104 to the pressure-dependent adjustment control 70 of the adjustment pump 66.

Die Pumpe 68 ist mit ihrem Einlass an einen Pumpensumpf 74 und mit ihrem Auslass über eine Vorlaufleitung 106 an den Einlass 42 des Steuerventils 14 angeschlossen. Eine vierte Überschussleitung 108 verbindet den Überschussauslass 44 mit einem ersten Einlass 110 eines Druckauswahlventils 112, das in seinem Aufbau identisch übereinstimmt mit dem vorstehend beschriebenen Druckauswahlventil 88. Das Druckauswahlventil 112 ist mit seinem zweiten Einlass 114 an die Steuerleitung 104 und mit seinem Auslass 116 an die druckabhängige Verstellsteuerung 72 der Verstellpumpe 68 angeschlossen und zwar über eine Steuerleitung 118. Eine zentrale Ventilbohrung 120 verbindet die Anschlüsse 110, 114 und 116. Zur Steuerung des Ölstroms von den Einlässen 110 und 114 zum Auslass 116 sind erste und zweite Absperrkugeln 122, 124 vorgesehen, die mit ersten und zweiten Ventilsitzen 126 und 128 zusammenwirken. Zwischen den Absperrkugeln 122,124 ist in der Ventilbohrung 120 ein Stössel 130 hin und her verschieblich angeordnet, dessen Länge so bemessen ist, dass ein gleichzeitiges Anliegen der Absperrkugeln an ihren Ventilsitzen ausschliesst. Das Druckauswahlvetil 112 verbindet daher den jeweils geringeren Druck, der in der Steuerleitung 104 bzw. der vierten Überschussleitung 108 besteht, mit der Steuerleitung 118 und dadurch mit der Verstellsteuerung 72 der Verstellpumpe 68.The pump 68 is connected with its inlet to a pump sump 74 and with its outlet via a flow line 106 to the inlet 42 of the control valve 14. A fourth excess line 108 connects the excess outlet 44 to a first inlet 110 of a pressure selection valve 112, which is identical in construction to the pressure selection valve 88 described above. The pressure selection valve 112 is connected to the control line 104 with its second inlet 114 and to the control line 104 with its outlet 116 pressure-dependent adjustment control 72 of the adjustment pump 68 is connected, specifically via a control line 118. A central valve bore 120 connects the connections 110, 114 and 116. To control the oil flow from the inlets 110 and 114 to the outlet 116, first and second shut-off balls 122, 124 are provided, that cooperate with first and second valve seats 126 and 128. Between the shut-off balls 122, 124, a plunger 130 is slidably arranged back and forth in the valve bore 120, the length of which is dimensioned in such a way that the shut-off balls do not lie against their valve seats at the same time. The pressure selection valve 112 therefore connects the respectively lower pressure, which exists in the control line 104 or the fourth excess line 108, to the control line 118 and thereby to the adjustment control 72 of the adjustment pump 68.

Eine Bypass-Schaltung umfasst eine Bypass-Leitung 132, die zwischen die vierte Überschussleitung 108 sowie die Vorlaufleitung 76 geschaltet ist und ein Einwegventil 134 aufweist, das den Ölstrom lediglich in Richtung von der Leitung 108 zur Leitung 76 zulässt. Wenn also der Druck in der Leitung 108 grösser ist als der in der Steuerleitung 104, verhindert das Druckauswahlventil 112 einen Ölstrom von der Leitung 108 zu der Steuerleitung 118; der Druck in der Leitung 108 öffnet dann das Ventil 134 und verbindet dadurch die Überschussleitung 108 mit der Vorlaufleitung 76, so dass sich die von der Pumpe 68 erzeugte Fördermenge mit der Pumpe 66 addiert.A bypass circuit comprises a bypass line 132 which is connected between the fourth excess line 108 and the flow line 76 and has a one-way valve 134 which only allows the oil flow in the direction from line 108 to line 76. Thus, if the pressure in line 108 is greater than that in control line 104, pressure selection valve 112 prevents oil flow from line 108 to the control line 118; the pressure in line 108 then opens valve 134 and thereby connects excess line 108 to flow line 76, so that the delivery volume generated by pump 68 is added to pump 66.

Um eine schnellere Anpassung der Verstellpumpe 66 an die Bedarfswechsel der von dem Ventil 12 bedienten Stützfussfunktionen zu ermöglichen, ist in der zu dem Ventil 12 führenden bzw. von diesem Ventil wegführenden Schaltung ein Paar Leitungskompensatoren 136, 138 vorgesehen. Letztere umfassen jeweils abgesetzte zylindrische Kammern 140, 142, von denen die Kammer 140 mit einem kleinen Ende über eine Leitung 144 an die Vorlaufleitung 76 angeschlossen ist, während die Kammer 142 mit einem kleinen Ende über eine Leitung 146 an die erste Überschussleitung 78 angeschlossen ist. Beide Kammern 140, 142 sind jeweils mit ihren grossen Enden miteinander sowie mit der Steuerleitung 104 über eine gegabelte Leitung 148 verbunden. In den kleinen und grossen Abschnitten der Kammer 140 ist jeweils ein kleiner sowie ein grosser Kolben 150 und 152 hin und her verschiebbar angeordnet, die über eine Kolbenstange 154 miteinander verbunden sind. An gegenüberliegenden Seiten des grossen Kolbens 152 ist ein Paar von Zentrierfedern 156, 158 vorgesehen, die den Kolben 152 in eine Mittelstellung im grossen Abschnitt der Kammer 140 drücken. Entsprechend hat auch die Kammer 142 einen kleinen und einen grossen Kolben 160,162, die hin und her verschieblich angeordnet und über eine Kolbenstange 164 miteinander verbunden sind. Ein Paar von Zentrierfedern 166, 168 ist auf den gegenüberliegenden Seiten des grossen Kolbens 162 vorgesehen.In order to enable the variable displacement pump 66 to be adapted more quickly to the changes in the support foot functions operated by the valve 12, a pair of line compensators 136, 138 are provided in the circuit leading to the valve 12 or leading away from this valve. The latter each include stepped cylindrical chambers 140, 142, of which the chamber 140 is connected to the flow line 76 with a small end via a line 144, while the chamber 142 is connected with a small end to the first excess line 78 via a line 146. Both chambers 140, 142 are each connected with their large ends to one another and to the control line 104 via a forked line 148. A small and a large piston 150 and 152, which are connected to one another via a piston rod 154, are displaceably arranged in the small and large sections of the chamber 140. On opposite sides of the large piston 152, a pair of centering springs 156, 158 are provided which press the piston 152 into a central position in the large section of the chamber 140. Correspondingly, the chamber 142 also has a small and a large piston 160, 162, which are arranged such that they can be moved back and forth and are connected to one another via a piston rod 164. A pair of centering springs 166, 168 are provided on the opposite sides of the large piston 162.

Ergibt sich plötzlich ein hoher Ölbedarf zur Betätigung des Stützfusses, dessen Steuerung über das Stützfuss-Steuerventil 12 erfolgt, so wird der Überschussstrom in der Überschussleitung 78 abnehmen und so den auf den kleinen Kolben 160 des Leitungskompensators 138 wirkenden Druck verringern. Der Kolben 160 wird dann nach links verschoben aufgrund der nicht mehr ausbalancierten Kräfte, die sich aus einer Volumenzunahme im Ende des grossen Abschnitts der Kammer 142 ergeben, was zu einer Druckabnahme in der gegabelten Leitung 148 und dadurch wiederum zu einem Druckabfall in der Steuerleitung 104 führt. Die Verstellsteuerung 70 der Verstellpumpe 66 wird auf diesen Druckabfall durch Erhöhung der Pumpenfördermenge reagieren. Dieser vergrösserte Ölstrom wird zunächst einen Druckanstieg gegenüber dem kleinen Kolben 150 des Leitungskompensators 136 bewirken, worauf die nicht mehr ausbalancierten Kräfte den Kolben nach links schieben, so dass der grosse Kolben 152 Öl aus dem grossen Ende der Kammer 140 drückt. Zu dieser Zeit wird der ursprüngliche Druckabfall in der Überschussleitung 78 vermutlich seinen Weg durch die Schaltung genommen haben und sich in der Steuerleitung 104 bemerkbar machen, so dass jeder Druckanstieg in der Steuerleitung 104 aufgrund der Linksverschiebung des Kolbens 152 überlagert wird durch den Druckabfall; die Fördermenge der Verstellpumpe 66 wird erhöht entsprechend einem etwaigen Netto-Druckabfall in der Steuerleitung 104.If there is suddenly a high oil requirement for actuating the support foot, which is controlled via the support foot control valve 12, the excess current in the excess line 78 will decrease and thus reduce the pressure acting on the small piston 160 of the line compensator 138. The piston 160 is then shifted to the left due to the unbalanced forces resulting from an increase in volume in the end of the large section of the chamber 142, which leads to a decrease in pressure in the bifurcated line 148 and, in turn, a pressure drop in the control line 104 . The adjustment control 70 of the adjustment pump 66 will react to this pressure drop by increasing the pump delivery rate. This increased oil flow will initially cause an increase in pressure relative to the small piston 150 of the line compensator 136, whereupon the unbalanced forces push the piston to the left so that the large piston 152 presses oil out of the large end of the chamber 140. At this time, the initial pressure drop in excess line 78 will likely have made its way through the circuit and become apparent in control line 104 so that any pressure increase in control line 104 due to the left displacement of piston 152 will be overlaid by the pressure drop; the delivery rate of the variable displacement pump 66 is increased in accordance with a possible net pressure drop in the control line 104.

In der gegabelten Leitung 148 liegt der Auslass 170 eines von einem Solenoid betätigten Druckbegrenzungsventils 172, das mit seinem Einlass 174 an die Vorlaufleitung 76 angeschlossen ist und zwar über einen Abschnitt der Bypass-Leitung 132 stromabwärts des Einwegventils 134. Das Druckbegrenzungsventil 172 ist in üblicher abgefallener Stellung dargestellt, in der es eine Strömungsverbindung zwischen der Leitung 132 und der Steuerleitung 104 unterbindet. Die Betätigung des Druckbegrenzungsventils 172 erfolgt zweckmässigerweise in Abhängigkeit des Abfalls der Ausgangsdrehzahl des Baggerantriebsmotors auf ein vorgegebenes Miminum. Es kann jede bekannte Drehzahlmessschaltung für die genannte Ausgangsdrehzahl verwendet werden, um den Elektromagneten des Druckbegrenzungsventils 172 dann zu erregen, wenn die Motordrehzahl ein vorgegebenes Minimum unterschreitet. Bei entsprechender Erregung stellt das Druckbegrenzungsventil 172 die Verbindung mit der Leitung 132 und damit mit dem Ausgang der Pumpe 66 und dem durch das Einwegventil 134 in die Steuerleitung 104 fliessenden Ölstrom. Dadurch wird der Druck in der Verstellsteuerung 70 erhöht, wodurch wiederum die Fördermenge der Pumpe 66 verringert wird, was seinerseits eine Teilbelastung vom Antriebsmotor nimmt und dadurch deren Geschwindigkeitsabfall verhindert.In the bifurcated line 148 is the outlet 170 of a solenoid actuated pressure relief valve 172 which has its inlet 174 connected to the flow line 76 via a portion of the bypass line 132 downstream of the one-way valve 134. The pressure relief valve 172 is more commonly decayed Position shown in which it prevents a flow connection between the line 132 and the control line 104. The pressure-limiting valve 172 is expediently actuated as a function of the drop in the output speed of the excavator drive motor to a predetermined minimum. Any known speed measurement circuit for said output speed can be used to energize the solenoid of the pressure relief valve 172 when the engine speed drops below a predetermined minimum. With appropriate excitation, the pressure relief valve 172 provides the connection to the line 132 and thus to the outlet of the pump 66 and the oil flow flowing through the one-way valve 134 into the control line 104. As a result, the pressure in the adjustment control 70 is increased, which in turn reduces the delivery rate of the pump 66, which in turn takes a partial load on the drive motor and thereby prevents its drop in speed.

Die Arbeitsweise des hydraulischen Steuersystems 10 lässt sich kurz wie folgt beschreiben: Während der Arbeit des Baggers teilen die Steuerventile 12, 14, 16 und 18 vorhandenen Ölstrom zwischen der jeweils ausgeübten Funktion und dem Überschussauslass des Ventils auf. So wird z.B. der Anteil des bei dem Stützfuss-Steuerventil 12 ankommenden Ölstromes, der für die Funktionsausübung nicht benötigt wird, an das rechte und linke Fahr-Steuerventil 16, 18 über die Überschussleitung 78 weitergeleitet. Der Anteil dieses bei den Steuerventilen 16, 18 ankommenden Ölstromes, der nicht zur Betätigung der Fahrfunktionen benötigt wird, wird an die Überschussleitungen 80, 82 weitergeleitet. Das Druckauswahlventil 88 arbeitet dann in Abhängigkeit der Druckzunahme in den Leitungen 80, 82, um Druckabfälle in den Leitungen 80, 82 an die Steuerleitung 104 und damit an die Verstellsteuerung 70 der Verstellpumpe 66 weiterzugeben. Die Verstellsteuerung 70 arbeitet in Abhängigkeit von dem in der Steuerleitung 104 herrschenden Druck, um eine Pumpenverstellung zu bewirken, die nur zu einer geringfügig grösseren von der Pumpe 66 geförderten Ölmenge führt, also zur Betätigung der Stützfuss- und/oder Fahr-Funktionen erforderlich ist.The operation of the hydraulic control system 10 can be briefly described as follows: During the work of the excavator, the control valves 12, 14, 16 and 18 divide the existing oil flow between the function performed in each case and the excess outlet of the valve. For example, the portion of the oil flow arriving at the support foot control valve 12, which is not required for the function, is passed on to the right and left travel control valves 16, 18 via the excess line 78. The proportion of this oil flow arriving at the control valves 16, 18, which is not required to actuate the driving functions, is passed on to the excess lines 80, 82. The pressure selection valve 88 then operates as a function of the pressure increase in the lines 80, 82 in order to pass on pressure drops in the lines 80, 82 to the control line 104 and thus to the adjustment control 70 of the adjustment pump 66. The adjustment control 70 operates in dependence on the pressure prevailing in the control line 104 in order to bring about a pump adjustment which only leads to a slightly larger amount of oil delivered by the pump 66, that is to say it is necessary to actuate the support foot and / or driving functions.

Inzwischen wird derjenige Anteil des beim Steuerventil 14 zum Verschwenken der Kabine ankommenden Ölstromes, der nicht zur Verschwenkung benötigt wird, zu der Überschussleitung 108 weitergeleitet. Das Druckauswahlventil 112 arbeitet in Abhängigkeit von dem Flüssigkeitsdruck in der Steuerleitung 104 und in der Überschussleitung 108, um den jeweils geringeren Druck mit der Steuerleitung 118 und dadurch mit der Verstelleinrichtung 72 der Verstellpumpe 68 zu verbinden. Ist der Druck in der Leitung 108 grösser als in der Leitung 132, öffnet das Einwegeventil 134 und verbindet dadurch den Ölstrom der Überschussleitung 108 mit der von der Verstellpumpe 66 geförderten Ölmenge. Dadurch kann die Pumpe 68 zeitweise die Pumpe 66 bei der Vesorgung der Stützfuss- und Fahr-Funktionen mit ungewöhnlich hohen Ölmengen unterstützen. Dadurch kommt die Pumpe 66 mit einer kleineren Verstellung aus als es sonst der Fall wäre.In the meantime, that portion of the oil flow arriving at the control valve 14 for pivoting the cabin that is not required for pivoting is forwarded to the excess line 108. The pressure selection valve 112 operates depending on the liquid pressure in the control line 104 and in the over shot line 108 to connect the respectively lower pressure with the control line 118 and thereby with the adjusting device 72 of the variable pump 68. If the pressure in line 108 is greater than in line 132, the one-way valve 134 opens and thereby connects the oil flow of the excess line 108 to the oil quantity delivered by the variable pump 66. As a result, the pump 68 can temporarily support the pump 66 in supplying the support leg and driving functions with unusually high amounts of oil. As a result, the pump 66 manages with a smaller adjustment than would otherwise be the case.

Claims (6)

1. Hydraulic system (10) with two variable displacement pumps (66, 68) which each supply a group of control valves (12, 14, 16, 18) with overflow outlets (30, 44, 58, 60), wherein a supply of pressure medium from the one system to the other is possible, characterized in that the first inlet (110) of a pressure selection valve (112) is connected to the overflow outlet (44) of a preferential control valve (14) fed by the second variable displacement pump (68), the second inlet (114) of the pressure selection valve (112) is connected to the overflow outlet (58, 60) of a subordinate control valve (16, 18) fed by the first variable displacement pump (66) as well as to the pressure-dependent displacement control (70) of the first variable displacement pump (66), and the outlet (116) of the pressure selection valve (112) is connected to the pressure-dependent displacement control (72) of the second variable displacement pump (68), in that the pressure selection valve (112) passes the lower of the two input pressures to the displacement control (72) of the second variable displacement pump (68), and in that there is provided a bypass with a bypass line (132), which connects the first inlet (110) of the pressure selection valve (112) to the inlet (28) of the preferential control valve (12) fed from the first variable displacement pump (66) and includes a one-way valve (134) which prevents flow in the direction of the pressure selection valve (112).
2. Hydraulic system according to claim 1, characterized in that the hydraulic system (10) comprises two subordinate control valves (16, 18) fed from the first variable displacement pump (66), whose overflow outlets (58, 60) are connected to the inputs (84, 86) of a further pressure selection valve (88), whose outlet (90) is connected to the pressure-dependent displacement control (70) of the first variable displacement pumpt (66) and to the second inlet (114) of the pressure selection valve (112), and in that the further pressure selection valve (88) conveys the lower of the two inlet pressures to its outlet (90).
3. Hydraulic system according to claim 1 or 2, characterized in that, for the rapid adaptation of the first variable displacement pump (66) to changes in demand of the functions served by the preferential control valve (12) fed from the first variable displacement pump (66), two line compensators (136; 138) are provided which each comprise two cylindrical chambers (140; 142) of different diameters, in which is slideably arranged a piston pair (150, 152; 160, 162) connected by a piston rod (154; 164), whose pistons (152; 162) of greater diameter are held in a balanced middle position in the cylindrical chambers of greater diameter by spring elements (156, 158; 166, 168), which chambers are connected together and also to the control line (104) of the displacement control (70) of the first variable displacement pump (66) by a line (148), while the one cylindrical chamber (140) of smaller diameter is connected (144) to the flow line (76) of the first variable displacement pump (66) and the other cylindrical chamber (142) of smaller diameter is connected (146) to the first overflow line (78) of the preferential control valve (12) fed by the first variable displacement pump (66).
4. Hydraulic system according to claim 3, characterized in that the outlet of a pressure-limiting valve (172) lies in the line (148) connecting the two chambers (140; 142) together and also to the control line (104) of the displacement control (70) of the first variable displacement pump (66), the input (174) of the pressure-limiting valve being connected to the flow line (76) of the first variable displacement pump (66).
5. Hydraulic system according to claim 4, characterized in that the pressure-limiting valve (172) is actuated by a solenoid.
6. Hydraulic system according to claim 1 and 4 or 5, characterized in that the inlet (174) of the pressure-limiting valve (172) is connected via the bypass line (132) downstream of the one-way valve (134) to the flow line (76) of the first variable displacement pump (66).
EP83109740A 1980-06-19 1981-06-11 Hydraulic circuit with two variable flow pumps controlled by excess flow Expired EP0105473B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/161,082 US4335577A (en) 1980-06-19 1980-06-19 Hydraulic system having variable displacement pumps controlled by power beyond flow
US161082 1980-06-19

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
EP81104489.0 Division 1981-06-11

Publications (3)

Publication Number Publication Date
EP0105473A2 EP0105473A2 (en) 1984-04-18
EP0105473A3 EP0105473A3 (en) 1987-01-28
EP0105473B1 true EP0105473B1 (en) 1988-10-05

Family

ID=22579741

Family Applications (2)

Application Number Title Priority Date Filing Date
EP83109740A Expired EP0105473B1 (en) 1980-06-19 1981-06-11 Hydraulic circuit with two variable flow pumps controlled by excess flow
EP81104489A Expired EP0042547B1 (en) 1980-06-19 1981-06-11 Hydraulic circuit with a variable flow pump controlled by excess flow

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP81104489A Expired EP0042547B1 (en) 1980-06-19 1981-06-11 Hydraulic circuit with a variable flow pump controlled by excess flow

Country Status (11)

Country Link
US (1) US4335577A (en)
EP (2) EP0105473B1 (en)
JP (1) JPS5729801A (en)
AR (1) AR227546A1 (en)
AU (1) AU544947B2 (en)
BR (1) BR8103841A (en)
CA (1) CA1148446A (en)
DE (1) DE3167292D1 (en)
ES (1) ES503127A0 (en)
MX (1) MX153742A (en)
ZA (1) ZA814125B (en)

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4479349A (en) * 1981-11-19 1984-10-30 General Signal Corporation Hydraulic control system
DE3513452A1 (en) * 1985-04-15 1986-10-16 Mannesmann Rexroth GmbH, 8770 Lohr HYDRAULIC SYSTEM FOR SUPPLYING A HYDROSTATIC STEERING
DE4100988C2 (en) * 1991-01-15 2001-05-10 Linde Ag Hydraulic drive system
US5540050A (en) * 1994-03-01 1996-07-30 Caterpillar Inc. Hydraulic system providing a positive actuator force
US5615553A (en) * 1995-06-28 1997-04-01 Case Corporation Hydraulic circuit with load sensing feature
US6672399B2 (en) 2001-10-19 2004-01-06 Deere & Company Hydraulic diverting system for utility vehicle
US6735908B2 (en) 2002-04-22 2004-05-18 Inscape Corporation Straddle bin
SE0402233L (en) * 2004-07-26 2006-02-28 Volvo Constr Equip Holding Se Arrangement and procedure for steering a work vehicle
DE102004048684A1 (en) * 2004-10-06 2006-04-13 Bosch Rexroth Ag Hydraulic control arrangement
US7401465B2 (en) * 2005-11-16 2008-07-22 Deere & Company Dual pump dual pressure hydraulic circuit
US7954317B2 (en) * 2007-12-21 2011-06-07 Deere & Company Hydraulic system
US9133837B2 (en) * 2008-04-24 2015-09-15 Caterpillar Inc. Method of controlling a hydraulic system
US8483916B2 (en) 2011-02-28 2013-07-09 Caterpillar Inc. Hydraulic control system implementing pump torque limiting
KR20140074324A (en) 2011-10-07 2014-06-17 볼보 컨스트럭션 이큅먼트 에이비 Priority control system for construction machine
US9347200B2 (en) 2012-06-04 2016-05-24 Cnh Industrial America Llc Fluid control system for work vehicle
GB201419777D0 (en) * 2014-11-06 2014-12-24 Agco Int Gmbh Hydraulic pressure supply system
CN106678099B (en) * 2017-01-20 2018-06-22 徐州徐工施维英机械有限公司 The power hydraulic system of concrete construction machinery and concrete construction machinery
DE102017005479A1 (en) * 2017-06-08 2018-12-13 Hydac Systems & Services Gmbh Pressure supply device
DE102017126505B4 (en) * 2017-11-10 2023-06-15 Syn Trac Gmbh Hydraulic system for a vehicle and a vehicle with such a hydraulic system
JP6917871B2 (en) * 2017-11-22 2021-08-11 キャタピラー エス エー アール エル Hydraulic control circuit for construction machinery
CN113638809B (en) * 2021-07-26 2022-11-18 中国联合重型燃气轮机技术有限公司 Emergency breaking device for heavy combustion engine

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3455210A (en) * 1966-10-26 1969-07-15 Eaton Yale & Towne Adjustable,metered,directional flow control arrangement
US3465519A (en) * 1967-08-18 1969-09-09 Webster Electric Co Inc Hydraulic flow controlling apparatus
US3718159A (en) * 1971-01-20 1973-02-27 Hydraulic Industries Control valve
US3863449A (en) * 1973-08-27 1975-02-04 Trw Inc Hydraulic motor fluid flow circuitry
US4024710A (en) * 1976-03-25 1977-05-24 Koehring Company Load sensing hydraulic circuit having power matching means

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2716995A (en) * 1950-09-23 1955-09-06 Gen Motors Corp Valve for reversible fluid pump
US2892311A (en) * 1958-01-08 1959-06-30 Deere & Co Hydraulic apparatus
LU52175A1 (en) * 1965-10-21 1966-12-19
US3760689A (en) * 1972-02-24 1973-09-25 Harnischfeger Corp Control system for automatically sequencing operation of a plurality of hydraulic pumps for supplying a plurality of hydraulic actuators
DE2435602C3 (en) * 1974-07-24 1980-06-12 International Harvester Company Mbh, 4040 Neuss Automatic control device for distributing the pressure medium to two hydraulic systems
US3987623A (en) * 1976-01-23 1976-10-26 Caterpillar Tractor Co. Controlled priority fluid system of a crawler type vehicle
US3998053A (en) * 1976-03-15 1976-12-21 Caterpillar Tractor Co. Three-pump - three-circuit fluid system of a work vehicle having controlled fluid-combining means
US3991571A (en) * 1976-03-15 1976-11-16 Caterpillar Tractor Co. Fluid system of a work vehicle having fluid combining means and signal combining means
US4023364A (en) * 1976-07-19 1977-05-17 Caterpillar Tractor Co. Swing flow supplemental travel for an excavator
US4044786A (en) * 1976-07-26 1977-08-30 Eaton Corporation Load sensing steering system with dual power source
US4055046A (en) * 1976-12-22 1977-10-25 Caterpillar Tractor Co. Control system having override for fluid operated work elements
US4116001A (en) * 1977-08-01 1978-09-26 International Harvester Company Simplified load sensitive hydraulic system for use with a vehicle steering system
US4286502A (en) * 1979-10-15 1981-09-01 Caterpillar Tractor Co. Hydraulic load lifting system with automatic blocking valve
DE3071279D1 (en) * 1980-04-07 1986-01-16 Caterpillar Tractor Co Control for load sharing pumps

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3455210A (en) * 1966-10-26 1969-07-15 Eaton Yale & Towne Adjustable,metered,directional flow control arrangement
US3465519A (en) * 1967-08-18 1969-09-09 Webster Electric Co Inc Hydraulic flow controlling apparatus
US3718159A (en) * 1971-01-20 1973-02-27 Hydraulic Industries Control valve
US3863449A (en) * 1973-08-27 1975-02-04 Trw Inc Hydraulic motor fluid flow circuitry
US4024710A (en) * 1976-03-25 1977-05-24 Koehring Company Load sensing hydraulic circuit having power matching means

Also Published As

Publication number Publication date
JPS5729801A (en) 1982-02-17
US4335577A (en) 1982-06-22
EP0042547A3 (en) 1982-08-04
EP0105473A3 (en) 1987-01-28
MX153742A (en) 1986-12-30
ES8300959A1 (en) 1982-11-01
EP0042547B1 (en) 1984-11-21
BR8103841A (en) 1982-03-09
JPH0213164B2 (en) 1990-04-03
EP0042547A2 (en) 1981-12-30
DE3167292D1 (en) 1985-01-03
CA1148446A (en) 1983-06-21
AU544947B2 (en) 1985-06-27
AU7026181A (en) 1981-12-24
ZA814125B (en) 1983-01-26
AR227546A1 (en) 1982-11-15
ES503127A0 (en) 1982-11-01
EP0105473A2 (en) 1984-04-18

Similar Documents

Publication Publication Date Title
EP0105473B1 (en) Hydraulic circuit with two variable flow pumps controlled by excess flow
DE69019379T2 (en) COMBINED LOAD AND LOAD PRESSURE COMPENSATION VALVE.
DE69128882T3 (en) Hydraulic control system and direction switch valves
DE2733054C2 (en) Device for supplying pressurized fluid
DE69705498T2 (en) VALVE SYSTEM FOR PRESSURE COMPENSATING HYDRAULIC CONTROL
DE2457451C2 (en)
DE4005967A1 (en) LOAD-INDEPENDENT VALVE CONTROL FOR MULTIPLE SIMULTANEOUSLY CONTROLLABLE HYDRAULIC CONSUMERS
DE69132071T2 (en) Hydraulic system
DE3513582C2 (en) Proportionally operating hydraulic valve with information acquisition regarding the strongest pressures in the consumer circles
DE2651325A1 (en) LOAD-CONTROLLED FLOW SYSTEM
DE2514624B2 (en) Control device for at least one hydraulically operated double-acting consumer
DE2208842C2 (en) Drive of a steering device and several accessories for vehicles by a hydrostatic transmission
DE2440099C2 (en) Hydraulic arrangement
DE4137963A1 (en) Valve arrangement for load-independent control of several hydraulic user units - involves ratio of adjusted part flows remaining the same in supply of system with pressure medium
DE1810509B2 (en) HYDRAULIC CONTROL DEVICE FOR MULTIPLE CONSUMERS
WO1998034031A1 (en) Hydraulic control circuit for a priority and for a secondary hydraulic consumer
DE4129508C2 (en) Valve arrangement for supplying a consumer from two pressure medium sources
DE2542809A1 (en) LOAD CONTROLLED COMPENSATION DEVICE FOR PRESSURE AND FLOW RATE IN A HYDRAULIC SYSTEM
DE3219730C2 (en)
DE1951429B2 (en) HYDRAULIC CONTROL SYSTEM, IN PARTICULAR FOR MULTIPLE HYDRAULIC MOTORS
DE3823892C2 (en) Hydraulic system with two pumps
DE3504744C2 (en)
DE69216055T2 (en) HYDRAULIC CIRCUIT FOR SWIVELING WORKING DEVICE
DE102006032908A1 (en) Multi-way valve block with mechanical and electro-hydraulic actuators,
DE19646427A1 (en) Valve arrangement for control of hydraulic equipment of e.g. lifting gear of land cultivator

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AC Divisional application: reference to earlier application

Ref document number: 42547

Country of ref document: EP

AK Designated contracting states

Designated state(s): DE FR GB IT SE

ITCL It: translation for ep claims filed

Representative=s name: LENZI & C.

EL Fr: translation of claims filed
PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR GB IT SE

17P Request for examination filed

Effective date: 19870113

17Q First examination report despatched

Effective date: 19871005

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

ITF It: translation for a ep patent filed

Owner name: LENZI & C.

AC Divisional application: reference to earlier application

Ref document number: 42547

Country of ref document: EP

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT SE

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
REF Corresponds to:

Ref document number: 3176898

Country of ref document: DE

Date of ref document: 19881110

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19930518

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19930616

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19930628

Year of fee payment: 13

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19940611

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19940612

ITTA It: last paid annual fee
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19940714

Year of fee payment: 14

EUG Se: european patent has lapsed

Ref document number: 83109740.7

Effective date: 19950110

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19940611

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19950228

EUG Se: european patent has lapsed

Ref document number: 83109740.7

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19960301