EP0191275B1 - Anti-saturation system for hydraulic control circuits for working members of earth-moving machines - Google Patents

Anti-saturation system for hydraulic control circuits for working members of earth-moving machines Download PDF

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Publication number
EP0191275B1
EP0191275B1 EP85830286A EP85830286A EP0191275B1 EP 0191275 B1 EP0191275 B1 EP 0191275B1 EP 85830286 A EP85830286 A EP 85830286A EP 85830286 A EP85830286 A EP 85830286A EP 0191275 B1 EP0191275 B1 EP 0191275B1
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EP
European Patent Office
Prior art keywords
pressure
valve
working members
distributors
hydraulic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85830286A
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German (de)
French (fr)
Other versions
EP0191275A1 (en
Inventor
Piero Tha
Bernardo Sandrono
Giovanni Maria Testa
Raffaele Sandroni
Gerald Keith Warren
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.)
Vickers Systems GmbH
Trinova SpA
Original Assignee
Vickers Systems GmbH
Trinova SpA
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Filing date
Publication date
Application filed by Vickers Systems GmbH, Trinova SpA filed Critical Vickers Systems GmbH
Priority to AT85830286T priority Critical patent/ATE46940T1/en
Publication of EP0191275A1 publication Critical patent/EP0191275A1/en
Application granted granted Critical
Publication of EP0191275B1 publication Critical patent/EP0191275B1/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • 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
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/166—Controlling a pilot pressure in response to the load, i.e. supply to at least one user is regulated by adjusting either the system pilot pressure or one or more of the individual pilot command pressures
    • 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
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • 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
    • E02F9/226—Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
    • 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
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
    • 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
    • F15B2211/21—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/212—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being accumulators
    • 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed 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
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid 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
    • F15B2211/70—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
    • F15B2211/71—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

Definitions

  • the present invention relates in general to hydraulic control circuits for working members of earth-moving machines.
  • the invention relates to hydraulic circuits with pumps and pressure-compensated distributors, of the type including a supply source of hydraulic fluid under pressure and a plurality of hydraulic working members each of which is associated with a respective hydraulic distributor having a spool which can be set with continuous adjustment by respective pilot means in three positions corresponding to movement of the working member in a first direction, stoppage, and movement in a second direction opposite the first, and pressure compensating means associated with the supply source and the distributors for keeping the difference between the pressure supplied by the source and the pressure of the working members substantially constant.
  • Hydraulic circuits of the above-mentioned type are generally known, for example, from US-A-4,343,152 and US-A-3,543,646.
  • the object of the present invention is to avoid this disadvantage and this object is achieved by providing, in a hydraulic circuit of the type described above, an anti-saturation system characterised in that it includes valve means which, in the event of a decrease in the difference between the pressure supplied by the source and the pressure of the working members, act to reduce the delivery supplied to the working members by the respective distributors.
  • valve means which, in the event of a decrease in the difference between the pressure supplied by the source and the pressure of the working members, act to reduce the delivery supplied to the working members by the respective distributors.
  • Normally such valve means are constituted by depressurising valve means.
  • the anti-saturation system allows a reduction in the delivery taken by the working members by decreasing the passage areas of the various units formed by the spools of the distributors and their respective local compensators.
  • this may be effected by the association of the depressurising valve means with either the pilot means for the distributors or the compensating means for the distributors.
  • the depressurising valve means act conveniently to reduce the maximum pilot pressure transmitted to the distributors by the hydraulic servocontrol devices.
  • the balancing pressures acting on the compensators associated with the distributors are conveniently reduced, unbalancing the compensators in such a way that they close and restrict the delivery taken by these compensators.
  • the depressurising valve means may operate automatically in response to the difference between the pressure supplied by the source and that of the working members, or they may be operated by a voluntary control in order to achieve the conditions of non-saturation of the circuit.
  • FIG. 1 illustrates schematically the essential components of a hydraulic control circuit for the working members of an earth-moving machine.
  • these working members comprise a series of hydraulic linear actuators 1 serving to operate the excavating arm (positioning-raising-penetration-reverse excavation) and a series of rotary actuators 2 for the translational movements of the excavator and rotation of the excavating arm.
  • the actuators 1 and 2 are arranged in two distinct groups in the drawing purely for the convenience of illustration.
  • respective spool distributors 3, 4 of known types are provided, each of which can be set in three conditions corresponding respectively to movement of the respective actuator 1, 2 in a first direction, stoppage, and movement in a second direction opposite the first.
  • the inlet- outlet connections between the distributors 3, 4 and the respective actuators 1, 2 are indicated A 1' 8 1 ?? A 7 , B 7 in the drawing.
  • the settling of the spools of the distributors 3, 4 in the three possible conditions is achieved by the hydraulic piloting effected by a servocontrol valve unit, generally indicated 5, including a series of lever and pedal controls which can be put manually into different positions corresponding to the three conditions of the distributors 3, 4.
  • the outlet-inlet connections between the servocontrols 5 and the respective distributors 3, 4 are indicated a 1' b 1 .... a 7 , b 7 .
  • the pump 6 has a known type of "load sensing" control which employs a control circuit 8 with selector ball valves which make use of the greater of the pressure signals from the distributors 3, 4 in operation.
  • Each of the distributors 3, 4 also has a respective associated compensator 9 constituted, in known manner, by a normally-open, two-way directional control valve which has one side connected to the respective working member 1, 2 downstream of the respective distributor 3, 4 and the opposite side connected to the inlet of the respective distributor 3, 4.
  • the compensator devices 9 have the well-known function of keeping the difference between the pressure supplied by the pump 6 and that of the working members 1, 2 substantially constant in use, in order to ensure simultaneity of the various possible working movements of the machine independently of the loads controlled.
  • the hydraulic servocontrol devices 5 are supplied by the pump 7 under the control of a maximum pressure valve 11.
  • the maximum pressure valve 11 has an associated depressurising valve (vent valve), indicated 10, the function of which is to prevent the hydraulic circuit becoming saturated.
  • the valve 10 is constituted by an automatically-piloted, two-way control valve having one side sensitive to the pressure supplied by the pump 6 and the opposite side sensitive to the pressure in the circuit 8, that is, to the greatest of the pressures of the working members 1, 2.
  • vent valve 10 allows the maximum pilot pressure of the distributors 3, 4 to be reduced as a result of the opening of the maximum pressure valve 11 as soon as the difference between the pressure delivered by the pump 6 and the pressure of the working members 1, 2 plus the elastic load acting on the valve 10 in the same sense as the pressure of the working members 1, 2 tends to fall, that is, when the circuit tends to become saturated.
  • the reduction in the pilot pressure involves a reduction in the delivery taken up and hence ensures the simultaneity of the various movements of the working members 1 and 2 in every case.
  • FIG. 2 illustrates a circuit similar to that described above and therefore only the differences will be explained in detail, the same reference numerals being used for parts identical or similar to those of Figure 1.
  • the circuit differs from that described above solely in that the servocontrol devices 5 are supplied by the same pump 6 through a pressure reduction valve 12.
  • the vent valve 10 acts on the pressure reduction valve 12, with an effect entirely similar to that described above.
  • vent valve 10 could be operated voluntarily by the operator instead of automatically. This operation, which can be carried out mechanically, hydraulically, electrically or even pneumatically, must be effected so as to bring the pilot pressure of the distributors 3, 4 to a value such as to satisfy the non-saturated conditions of the circuit.
  • pilot pressure could be achieved by systems different from the vent valve 10, for example by means of a pressuring valve or by means of control systems in parallel with the existing pilot pressure control system and actuated by the reduction of the difference between the delivered pressure and that of the working members 1, 2 below a calibrated value.
  • the two-way control valve 10 sensitive on one side to the pressure of the main pump 6 and on the opposite side to the pressure of the working members 1, 2, is placed in parallel to the maximum pressure valve 11 through which the maximum pilot pressure of the distributors 3, 4 is shutted.
  • an accumulator 13 is provided on the line connecting such pump 7 and the valve 11.
  • the accumulator can have a capacity of 0.70 liter and a pre-loading pressure in the range of 13 bar.
  • a second accumulator 14 is provided for stabilizing the rate of flow controlled by the valve 10 and for making up the rate of flow requests of the servocontrol devices 5.
  • the accumulator 14 has a capacity corresponding to a half of that of accumulator 13, i.e. of 0.35 liter, and a pre-loading pressure also of about 13 bar.
  • valve 15 having the function of preventing fluid reflow towards the pump 7, and a restriction 16 for the calibration of the rate of flow towards the valve 10 are provided between valve 10 and pump 7.
  • the circuit of Figure 4 further comprises a twoways and two-positions valve 17 placed downstream the valve 10 and hydraulically piloted by means of a pressure signal of the pump 7, the function of which is that of allowing no-load maneuvers of the working member in case of stop of the heat engine of the machine.
  • an anti-stall circuit of the valve 10 having the function of avoiding that the latter intervene so as to prevent any action by the working members 1, 2 in the situation in which one of the working members (for instance one of the cylinders 1) is at the end of stroke, and thus the pressure supplied by the pump 6 and the load signal pressure are equal and same to the maximum pressure of the circuit.
  • the said anti-stall circuit comprises a pressure reduction valve 18 placed in the piloting line of the valve 10 by the working members pressure.
  • the valve 18 is calibrated so as to prevent the intervention of the valve 10 in the above mentioned conditions, and to calibrated restrictions 19, 20 are associated thereto, the function of which is that of avoiding influences by the valve 18 on the load signal.
  • the invention also provides for acting on the restriction of the delivery taken up by the working members 1, 2 rather than on the maximum pilot pressure, by operating on the compensating device 9. This possibility is illustrated in Figure 3, in which parts identical or similar to those already described above are indicated by the same reference numerals.
  • vent valve 10 acts in such a way as to effect closure of the compensators 9, so as to reduce the delivery to the working members 1, 2 in a manner proportional to the respective control areas of the distributors 3, 4, until equilibrium between the delivery supplied and that taken up is re-established.
  • vent valve 10 could be controlled voluntarily.

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  • 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)

Abstract

An anti-saturation system for hydraulic control circuits with pumps and pressure-compensated distributors (3, 4) for working members (1, 2) of earth-moving machines, including depressurising valve means (10) which, in the event of a decrease in the difference between the pressure delivered by the pump (6, 7) and that of the working members (1, 2), act to reduce the delivery supplied to the working members (1, 2) by the respective distributors (3, 4).

Description

  • The present invention relates in general to hydraulic control circuits for working members of earth-moving machines.
  • In particular, the invention relates to hydraulic circuits with pumps and pressure-compensated distributors, of the type including a supply source of hydraulic fluid under pressure and a plurality of hydraulic working members each of which is associated with a respective hydraulic distributor having a spool which can be set with continuous adjustment by respective pilot means in three positions corresponding to movement of the working member in a first direction, stoppage, and movement in a second direction opposite the first, and pressure compensating means associated with the supply source and the distributors for keeping the difference between the pressure supplied by the source and the pressure of the working members substantially constant.
  • Hydraulic circuits of the above-mentioned type are generally known, for example, from US-A-4,343,152 and US-A-3,543,646.
  • It is known that such pressure compensating means also have the function of ensuring the simultaneity of all the movements of the working members (boom, bucket, depper, swing) independently of the controlled loads.
  • In hydraulic circuits of this type, whenever the total delivery taken up by the working members tends to be equal to or greater than the delivery supplied by the pump, the system finds itself under saturation conditions. In other words, the pump can no longer increase its delivery to establish a constant pressure difference between the pressure of the load and the supplied pressure, and this pressure difference tends to diminish when the demand of the working members which are being operated increases at the moment of saturation or if new working members are actuated. In this situation, the pressure compensating means associated with the distributors are fully open and are unable to restrict the deliveries to the respective working members. In short, the delivery goes to the working member at the lower pressure and the simultaneity of the movement is consequently lost.
  • The object of the present invention is to avoid this disadvantage and this object is achieved by providing, in a hydraulic circuit of the type described above, an anti-saturation system characterised in that it includes valve means which, in the event of a decrease in the difference between the pressure supplied by the source and the pressure of the working members, act to reduce the delivery supplied to the working members by the respective distributors. Normally such valve means are constituted by depressurising valve means.
  • In practice, the anti-saturation system according to the invention allows a reduction in the delivery taken by the working members by decreasing the passage areas of the various units formed by the spools of the distributors and their respective local compensators.
  • According to the invention, this may be effected by the association of the depressurising valve means with either the pilot means for the distributors or the compensating means for the distributors.
  • In the first case, whenever the pilot means for the distributors include hydraulic servocontrol devices, the depressurising valve means act conveniently to reduce the maximum pilot pressure transmitted to the distributors by the hydraulic servocontrol devices.
  • In the second case, the balancing pressures acting on the compensators associated with the distributors are conveniently reduced, unbalancing the compensators in such a way that they close and restrict the delivery taken by these compensators.
  • In each case, the depressurising valve means may operate automatically in response to the difference between the pressure supplied by the source and that of the working members, or they may be operated by a voluntary control in order to achieve the conditions of non-saturation of the circuit.
  • The invention will be described in detail with reference to the appended drawings provided purely by way of non-limiting example, in which:
    • Figure 1 is a diagram of a hydraulic control circuit provided with an anti-saturation system .according to the invention, Figure 2 illustrates a first variant of Figure 1,
    • Figure 3 shows a second variant of Figure 1, and
    • Figure 4 shows a further variant of a part of the circuit of Figure 1.
  • Figure 1 illustrates schematically the essential components of a hydraulic control circuit for the working members of an earth-moving machine. In the example illustrated, these working members comprise a series of hydraulic linear actuators 1 serving to operate the excavating arm (positioning-raising-penetration-reverse excavation) and a series of rotary actuators 2 for the translational movements of the excavator and rotation of the excavating arm. The actuators 1 and 2 are arranged in two distinct groups in the drawing purely for the convenience of illustration.
  • For supplying and discharging the actuators 1 and 2, respective spool distributors 3, 4 of known types are provided, each of which can be set in three conditions corresponding respectively to movement of the respective actuator 1, 2 in a first direction, stoppage, and movement in a second direction opposite the first. The inlet- outlet connections between the distributors 3, 4 and the respective actuators 1, 2 are indicated A 1' 81 ..... A7, B7 in the drawing.
  • The settling of the spools of the distributors 3, 4 in the three possible conditions is achieved by the hydraulic piloting effected by a servocontrol valve unit, generally indicated 5, including a series of lever and pedal controls which can be put manually into different positions corresponding to the three conditions of the distributors 3, 4. The outlet-inlet connections between the servocontrols 5 and the respective distributors 3, 4 are indicated a1' b1.... a7, b7.
  • The supply of the distributors 3,4 (and hence of the working members 1, 2) and that of the servocontrols 5 is effected, in the case of Figure 1, by two separate hydraulic pumps 6, 7.
  • The pump 6 has a known type of "load sensing" control which employs a control circuit 8 with selector ball valves which make use of the greater of the pressure signals from the distributors 3, 4 in operation.
  • Each of the distributors 3, 4 also has a respective associated compensator 9 constituted, in known manner, by a normally-open, two-way directional control valve which has one side connected to the respective working member 1, 2 downstream of the respective distributor 3, 4 and the opposite side connected to the inlet of the respective distributor 3, 4. The compensator devices 9 have the well-known function of keeping the difference between the pressure supplied by the pump 6 and that of the working members 1, 2 substantially constant in use, in order to ensure simultaneity of the various possible working movements of the machine independently of the loads controlled.
  • The hydraulic servocontrol devices 5 are supplied by the pump 7 under the control of a maximum pressure valve 11. According to the invention, the maximum pressure valve 11 has an associated depressurising valve (vent valve), indicated 10, the function of which is to prevent the hydraulic circuit becoming saturated. The valve 10 is constituted by an automatically-piloted, two-way control valve having one side sensitive to the pressure supplied by the pump 6 and the opposite side sensitive to the pressure in the circuit 8, that is, to the greatest of the pressures of the working members 1, 2.
  • It will become apparent that the vent valve 10 allows the maximum pilot pressure of the distributors 3, 4 to be reduced as a result of the opening of the maximum pressure valve 11 as soon as the difference between the pressure delivered by the pump 6 and the pressure of the working members 1, 2 plus the elastic load acting on the valve 10 in the same sense as the pressure of the working members 1, 2 tends to fall, that is, when the circuit tends to become saturated. Clearly, the reduction in the pilot pressure involves a reduction in the delivery taken up and hence ensures the simultaneity of the various movements of the working members 1 and 2 in every case.
  • Figure 2 illustrates a circuit similar to that described above and therefore only the differences will be explained in detail, the same reference numerals being used for parts identical or similar to those of Figure 1.
  • The circuit differs from that described above solely in that the servocontrol devices 5 are supplied by the same pump 6 through a pressure reduction valve 12. In this case the vent valve 10 acts on the pressure reduction valve 12, with an effect entirely similar to that described above.
  • It should be noted that the vent valve 10 could be operated voluntarily by the operator instead of automatically. This operation, which can be carried out mechanically, hydraulically, electrically or even pneumatically, must be effected so as to bring the pilot pressure of the distributors 3, 4 to a value such as to satisfy the non-saturated conditions of the circuit.
  • It is also clear that the reduction in the pilot pressure could be achieved by systems different from the vent valve 10, for example by means of a pressuring valve or by means of control systems in parallel with the existing pilot pressure control system and actuated by the reduction of the difference between the delivered pressure and that of the working members 1, 2 below a calibrated value.
  • A control system of this kind is shown in Figure 4, wherein parts corresponding to those of Figure 1 are indicated with the same reference numerals.
  • In this case the two-way control valve 10, sensitive on one side to the pressure of the main pump 6 and on the opposite side to the pressure of the working members 1, 2, is placed in parallel to the maximum pressure valve 11 through which the maximum pilot pressure of the distributors 3, 4 is shutted. In order to stabilize the pressure generated by the maximum pressure valve 11 and the rate of flow pulsated by the pump 7, an accumulator 13 is provided on the line connecting such pump 7 and the valve 11. For example, the accumulator can have a capacity of 0.70 liter and a pre-loading pressure in the range of 13 bar.
  • A second accumulator 14 is provided for stabilizing the rate of flow controlled by the valve 10 and for making up the rate of flow requests of the servocontrol devices 5. For example, the accumulator 14 has a capacity corresponding to a half of that of accumulator 13, i.e. of 0.35 liter, and a pre-loading pressure also of about 13 bar.
  • Moreover, a check valve 15, having the function of preventing fluid reflow towards the pump 7, and a restriction 16 for the calibration of the rate of flow towards the valve 10 are provided between valve 10 and pump 7.
  • The circuit of Figure 4 further comprises a twoways and two-positions valve 17 placed downstream the valve 10 and hydraulically piloted by means of a pressure signal of the pump 7, the function of which is that of allowing no-load maneuvers of the working member in case of stop of the heat engine of the machine.
  • To the valve 17 is further added an anti-stall circuit of the valve 10, having the function of avoiding that the latter intervene so as to prevent any action by the working members 1, 2 in the situation in which one of the working members (for instance one of the cylinders 1) is at the end of stroke, and thus the pressure supplied by the pump 6 and the load signal pressure are equal and same to the maximum pressure of the circuit. Just in order to avoid the intervention of the valve 10 in such situation, the said anti-stall circuit comprises a pressure reduction valve 18 placed in the piloting line of the valve 10 by the working members pressure. The valve 18 is calibrated so as to prevent the intervention of the valve 10 in the above mentioned conditions, and to calibrated restrictions 19, 20 are associated thereto, the function of which is that of avoiding influences by the valve 18 on the load signal.
  • The invention also provides for acting on the restriction of the delivery taken up by the working members 1, 2 rather than on the maximum pilot pressure, by operating on the compensating device 9. This possibility is illustrated in Figure 3, in which parts identical or similar to those already described above are indicated by the same reference numerals.
  • In this case, the vent valve 10 acts in such a way as to effect closure of the compensators 9, so as to reduce the delivery to the working members 1, 2 in a manner proportional to the respective control areas of the distributors 3, 4, until equilibrium between the delivery supplied and that taken up is re-established.
  • Again in this case, the vent valve 10 could be controlled voluntarily.
  • It should also be noted that, as an alternative to a single vent valve 10 connected to the control circuit 8, a series of such valves could be used, each associated with a respective distributor 3, 4.

Claims (11)

1. Anti-saturation system for hydraulic control circuits for working members (1, 2) of earth-moving machines, comprising a supply source of hydraulic fluid under pressure (6), a plurality of hydraulic working members (1, 2) each of which is associated with a respective hydraulic distributor (3, 4) having a spool which can be set with continuous adjustment by respective pilot means (5) in three positions corresponding to movement of the working member in a first direction, stoppage, and movement in a second direction opposite to the first, and pressure compensating means (9) associated with the supply source (6) and the distributors (3, 4) for keeping the difference between the pressure supplied by the source and the pressure of the working members substantially constant, characterised in that it includes valve means (10) which in the event of a decrease in the pressure difference, act to reduce the delivery supplied to the working members (1, 2) by the respective distributors (3, 4).
2. Anti-saturation system according to Claim 1, characterised in that the said valve means are constituted by depressurizing valve means (10) which are sensitive to the pressure difference and act automatically in response to decrease therein.
3. System according to Claim 2, characterised in that the depressurising valve means (10) are associated with pilot means (5) for the distributors (3, 4).
4. System according to Claim 2, characterised in that the depressurising valve means (10) act on the compensating means (9).
5. System according to Claim 3, in which the pilot means for the distributors (3, 4) include hydraulic servocontrol devices (5), characterised in that the depressurising valve means (10) act to reduce the maximum pilot pressure transmitted to the distributors (3, 4) by the hydraulic servo- control devices (5).
6. System according to Claim 5, having a secondary source of pressurised fluid (7) connected under the control of a maximum pressure valve (11) to the said hydraulic servocontrol devices (5) for transmitting pilot pressure to the distributors (3, 4), characterised in that the depressurising valve means (10) include a directional control valve sensitive on one side to the pressure of the primary supply source (6) and on the other to the pressure of the working members (1, 2), and arranged to control the opening of the maximum pressure valve (11).
7. System according to Claim 5, in which the servocontrol devices (5) are supplied by the supply source through a pressure reduction valve (12), characterised in that the depressurising valve means (10) include a control valve sensitive on one side to the pressure of the supply source (6) and on the other to the pressure of the working members (1, 2) plus an elastic load acting on the valve means (10) in the same sense as the pressure of the working members (1, 2), and arranged to control the opening of the pressure reduction valve (12).
8. System according to Claim 5, having a secondary source of pressurised fluid (7) connected under the control of a maximum pressure valve (11) to the said hydraulic servo-control devices (5) for transmitting pilot pressure to the distributors (3, 4), characterised in that the depressurising valve means comprise:
a directional control valve (10) sensitive on one side to the pressure of the primary supply source (6) and on the other to the pressure of the working members (1, 2), the said directional control valve being placed in parallel to the said maximum pressure valve and being adapted to effect opening thereof,
an anti-stall circuit of the said directional control valve (10) including a pressure reduction valve (18) calibrated for preventing the intervention of the directional control valve .(10) in the conditions in which the pressure supplied by the said primary supply source is equal to the pressure of the working members (1, 2) and same to the maximum pressure of the circuit.
9. System according to Claim 8, characterised in that it further comprises a first accumulator (13) for stabilising the rate of flow of the said secondary supply source (7) and the pressure generated by the said maximum pressure valve (11), and a second accumulator (14) for stabilising the pressure controlled by the said directional control valve (10).
10. System according to Claim 4, characterised in that the depressurising valve means include a directional control valve (10) sensitive on one side to the pressure of the supply source (6) and on the other to the pressure of the working member (1, 2) plus an elastic load acting on the valve means 10) in the same sense as the pressure of the working members (1, 2), and arranged to control the closure of the pressure compensating means (9) associated with the distributors (3, 4).
11. System according to Claim 2, characterised in that the depressurising valve means are controlled voluntarily.
EP85830286A 1985-02-14 1985-11-20 Anti-saturation system for hydraulic control circuits for working members of earth-moving machines Expired EP0191275B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85830286T ATE46940T1 (en) 1985-02-14 1985-11-20 ANTI-SATURATION SYSTEM FOR HYDRAULIC CONTROL CIRCUITS OF WORK EQUIPMENT OF EARTH-MOVING MACHINERY.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT8567149A IT1234937B (en) 1985-02-14 1985-02-14 ANTI-SATURATION SYSTEM FOR HYDRAULIC CONTROL CIRCUITS WITH PUMPS AND PRESSURE-CONTROLLED DISTRIBUTORS FOR WORKING PARTS OF EARTH-MOVING MACHINES
IT6714985 1985-02-14

Publications (2)

Publication Number Publication Date
EP0191275A1 EP0191275A1 (en) 1986-08-20
EP0191275B1 true EP0191275B1 (en) 1989-10-04

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EP85830286A Expired EP0191275B1 (en) 1985-02-14 1985-11-20 Anti-saturation system for hydraulic control circuits for working members of earth-moving machines

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AT (1) ATE46940T1 (en)
DE (1) DE3573453D1 (en)
IT (1) IT1234937B (en)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3546336A1 (en) * 1985-12-30 1987-07-02 Rexroth Mannesmann Gmbh CONTROL ARRANGEMENT FOR AT LEAST TWO HYDRAULIC CONSUMERS SUPPLIED BY AT LEAST ONE PUMP
IT1187892B (en) * 1986-02-04 1987-12-23 Chs Vickers Spa HYDRAULIC CONTROL CIRCUIT FOR WORKING BODIES OF EARTH-MOVING MACHINES WITH CENTRALIZED ACTUATOR BRAKING
IT1195178B (en) * 1986-09-24 1988-10-12 Chs Vickers Spa FLOW RATE RECOVERY SYSTEM FOR HYDRAULIC CIRCUITS WITH PUMPS AND PRESSURIZED PRESSURE INSTRUMENTS FOR WORKING PARTS OF EARTH-MOVING MACHINES
IT1208866B (en) * 1987-04-14 1989-07-10 Chs Vickers Spa HYDRAULIC CONTROL CIRCUIT FOR EARTH-MOVING MACHINE WORKING BODIES WITH ABOVE MENTION CIRCUIT
JP2582266B2 (en) * 1987-09-29 1997-02-19 新キヤタピラー三菱株式会社 Fluid pressure control system
GB2251232B (en) * 1990-09-29 1995-01-04 Samsung Heavy Ind Automatic actuating system for actuators of excavator
DK0515608T3 (en) * 1990-12-15 1995-06-12 Barmag Barmer Maschf Hydraulic System
JPH05504820A (en) * 1990-12-15 1993-07-22 バルマーク　アクチエンゲゼルシヤフト hydraulic system
DE4140423A1 (en) * 1991-12-07 1993-06-09 Mannesmann Rexroth Gmbh, 8770 Lohr, De System for regulating pressure of hydraulic working fluid in machine - has hydraulically operated control valve and pressure transducers for signalling pressure to comparator in electronic controller
FR2807118B1 (en) * 2000-03-28 2002-07-05 Mannesmann Rexroth Sa HYDRAULIC CIRCUIT FOR OPERATING MULTIPLE HYDRAULIC RECEIVERS
JP2007255506A (en) * 2006-03-22 2007-10-04 Komatsu Ltd Operation control circuit of construction machine
CN103062144B (en) * 2012-12-30 2015-08-12 徐工集团工程机械股份有限公司江苏徐州工程机械研究院 A kind of load sensing multi-way valve with anti-saturation function
JP6698199B1 (en) * 2019-07-24 2020-05-27 芝浦機械株式会社 Local pressure device

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3156098A (en) * 1959-11-20 1964-11-10 Ford Motor Co Hydraulic power system
US3146593A (en) * 1960-04-18 1964-09-01 Parker Hannifin Corp Dual pump system and control valve assembly therefor
DE1484743B1 (en) * 1963-04-24 1970-09-10 Orenstein & Koppel Ag Circuit for hydrostatically operated hydro devices
SE342871B (en) * 1967-11-24 1972-02-21 Mitsubishi Heavy Ind Ltd
FR2250908B3 (en) * 1973-11-14 1977-08-12 Massey Ferguson Services Nv
US4074529A (en) * 1977-01-04 1978-02-21 Tadeusz Budzich Load responsive system pump controls
US4343152A (en) * 1980-05-16 1982-08-10 Caterpillar Tractor Co. Load sensing porting arrangement

Also Published As

Publication number Publication date
IT1234937B (en) 1992-06-02
DE3573453D1 (en) 1989-11-09
ATE46940T1 (en) 1989-10-15
EP0191275A1 (en) 1986-08-20
IT8567149A0 (en) 1985-02-14

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