WO1981000742A1 - Controlled pressure upstaging and flow reduction - Google Patents

Controlled pressure upstaging and flow reduction Download PDF

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Publication number
WO1981000742A1
WO1981000742A1 PCT/US1979/000735 US7900735W WO8100742A1 WO 1981000742 A1 WO1981000742 A1 WO 1981000742A1 US 7900735 W US7900735 W US 7900735W WO 8100742 A1 WO8100742 A1 WO 8100742A1
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WO
WIPO (PCT)
Prior art keywords
circuit
pressure level
pressure
response
upstaged
Prior art date
Application number
PCT/US1979/000735
Other languages
English (en)
French (fr)
Inventor
D Bianchetta
S Rhodes
Original Assignee
Caterpillar Tractor Co
D Bianchetta
S Rhodes
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Caterpillar Tractor Co, D Bianchetta, S Rhodes filed Critical Caterpillar Tractor Co
Priority to JP50059080A priority Critical patent/JPS56501133A/ja
Priority to PCT/US1979/000735 priority patent/WO1981000742A1/en
Priority to CA000356034A priority patent/CA1141265A/en
Priority to EP80105575A priority patent/EP0025609B1/en
Priority to DE8080105575T priority patent/DE3063346D1/de
Publication of WO1981000742A1 publication Critical patent/WO1981000742A1/en

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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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/022—Systems essentially incorporating special features for controlling the speed or actuating force of an output member in which a rapid approach stroke is followed by a slower, high-force working stroke
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2282—Systems using center bypass type changeover valves
    • 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
    • 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
    • F15B2211/20538—Type of pump constant capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-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
    • F15B2211/3116—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
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3138—Directional control characterised by the positions of the valve element the positions being discrete
    • 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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
    • 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
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—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
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5157—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a 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
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure 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
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief 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
    • F15B2211/50—Pressure control
    • F15B2211/575—Pilot pressure control
    • F15B2211/5756—Pilot pressure control for opening a 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
    • F15B2211/60—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
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/67—Methods for controlling pilot 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
    • 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
    • F15B2211/7135—Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
    • 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

  • This invention relates to a control system which will allow upstaging of one of a plurality of working circuits fed from ⁇ a variable displacement pump with concomitant flow reduction.
  • a number of vehicles have a plurality of work circuits each supplied in interrupted series or in parallel from a single pressure compensated variable displacement pump. It is known to have some of the work circuits operable at higher pressures than other of the work circuits. For example, the track -drive of an excavator may be required to operate at higher pressure than the hydraulic motor which controls the stick or the boom. To accomplish this, the prior art has provided hydraulic control circuitry which will supply a higher pressure, and at times a lower flow rate as well, to a track drive working circuit and a relatively lower pressure to a stick motor or a boom motor.
  • U.S. Patent 4,107,924, issued August 22, 1978 to J..E. Dezelin illustrates a hydraulic circuit for an earthworking vehicle having such characteristics.
  • an operator it is desirable for an operator to be able to supply additional pressure to one of the hydraulic motors, for example, to the boom motor of an excavator when the boom is being raised. In fact, in such a situation it is desirable to be able to supply a higher pressure to the boom motor than is normally supplied even to the track drive.
  • an improvement is provided in a hydraulic system having a variable displacement pump and means for delivering pressurized fluid from the pump to selectively engage at least three work circuits, a first of the circuits being normally operable up to a first pressure and a second of the circuits being normally operable up to a second pressure which is less than the first pressure.
  • the improvement of the invention comprises means for selectively operating a third of the circuits at an upstaged pressure which exceeds the first pressure.
  • the single figure of the drawing is a diagramatic view, partially in section, of a hydraulic circuit which includes an improvement in accordance with an embodiment of the present invention.
  • a hydraulic system 10 which is particularly adapted for use with an earthworking vehicle such as an excavator.
  • the hydraulic system 10 includes a conventional pressure compensated variable displacement pump 12 for pumping hydraulic fluid from a sump via pressurized fluid delivery means 16 to selectively engage at least three work circuits 18.
  • the three work circuits 18 are a first work circuit 20, a second work circuit 22 and a third work circuit 24.
  • the first work circuit 20 is normally operable up to a first pressure, e.g., 28,000 kPa (4,061 psi) and the second work circuit 22 is normally operable up to a second pressure, e.g., 25,000 kPa (3,626 psi), which is less than the first pressure.
  • the pump 12 conventionally internally adjusts displacement dependent upon its output pressure.
  • the first work circuit 20 might typically be a track drive circuit of an excavator
  • the second circuit 22 might be a stick control circuit
  • the third circuit 24 might be a boom control circuit.
  • the pressurized fluid delivery means 16 delivers the fluid in interrupted series flow to main control valves 26c, 26b and 26a, respectively of work circuits 24, 22 and 20. That is, the valve 26c controls flow therethrough to the valve 26b, which in turn controls flow therethrough to the valve 26a. Hence, even if the valve 26c is partially shifted downwardly or upwardly, flow still passes therethrough to the valve 26b, and therethrough to the valve 26a.
  • the main control valves 26a, 26b and 26c are controlled respectively by pilot control valves 28a, 28b and 28c which receive pressurized fluid flow from a pilot pump 30.
  • pilot control valves 28a, 28b and 28c which receive pressurized fluid flow from a pilot pump 30.
  • pilot pump 30 When flow from pilot pump 30 is being supplied via pilot control valve 28a to first work circuit 20, either line 32a or line 34a is pressurized.
  • the pressure of the hiqher pressure of lines 32a and 34a is supplied by a resolver 36 to a pressure control line 38. This pressure is later utilized, in a manner which will become apparent, for limiting the pressure delivered by the pressurized fluid delivery means 16 to the work circuits 20, 22 and 24.
  • the pilot control valve 28b When the pilot control valve 28b is operated, either line 32b or line 34b. is pressurized.
  • a resolver 40 delivers the higher of these pressures to a conduit 42.
  • the pressure in the conduit 42 and the pressure in the pressure control line 38 are both fed to a resolver 44.
  • the higher of these pressures is delivered to an upstaged pressure blocking conduit 46 and utilized in a manner which will be explained below.
  • pressure relief valve circuitry 48 limits the pressure supplied by the pressurized fluid delivery means 16. Fluid from the pump 12 passes into a main conduit 50 from whence it flows to a first end 52 of a bore 54 in a body 56.
  • a main dump spool 58 sits in reciprocal relationship within the bore 54.
  • a spring 60 acts between a second end 62 of the bore 54 and the spool 58.
  • the spring 60 serves as means for biasing a first end 64 of the spool 58 into blocking relation with the first end 52 of the bore 54.
  • a restricted orifice 66 communicates the first end 64 of the spool 58 with a second end 68 thereof. As pressure builds up in the main conduit 50, pressurized fluid passes via the restricted orifice 66 through the dump spool 58. Thereby, a similar pressure builds up at the second end 62 of the bore 54.
  • a first relief valve 70 e.g., a poppet relief valve, is provided which is set to open at the first pressure (e.g., 28,000 kPa) .
  • the first relief valve 70 communicates via a conduit 72.with the second end 62 of the bore 54.
  • the first relief valve 70 is exposed to the pressure in the main conduit 50.
  • the first relief valve 70 thereby serves as a first pilot stage of the main dump spool 58.
  • a second relief valve 74 e.g., a poppet relief valve, is set to open at the second pressure (e.g., 25,000 kPa) .
  • the second relief valve 74 communicates with the second end 62 of the bore 54 via a conduit 76 and a continuation conduit 78.
  • the second relief valve 74 thereby serves as a second pilot stage of the main relief dump spool 58.
  • An upstaged pressure (e.g., 31,000 kPa or 4,496 psi) opening relief valve 80 communicates with the second end 62 of the bore 54 via the conduit 76 and a continuation conduit 82.
  • the upstaged pressure opening relief valve 80 thereby serves as an upstaged pilot stage of the main relief dump spool (58) .
  • a pressure differential is created across the dump spool 58 which lifts it upwardly in the drawing against the force of the spring 60.
  • a plurality of holes 84 through the side of the dump spool 58 adjacent the first end 64 thereof and a conduit 86 then serve as means for communicating the first end 52 of the bore 54 with the sump 14 responsive to upward movement of dump spool 58.
  • Means 90 are provided for blocking off communication of the second end 62 of the bore 54 with the second check valve 74 responsive to engagement of the first circuit 20.
  • pressure from the pressure control line 38 is delivered via a resolver 92 and a pressure delivery conduit 94 to a first end 96 of a blocking spool 98 which fits in a bore 100.
  • a spring 102 acts against a second end 104 of the blocking spool 98 to force it upwardly into the position shown in the drawing.
  • the dump spool 58 does not dump pressure from the main conduit 50 at the lower pressure, i.e., at the aforementioned second pressure (e.g. 25000 kPa). Instead, when the pressure in the main conduit 50 reaches the first pressure (e.g., 28,000 kPa) , the first relief valve 70 opens which causes the dump spool 58 to limit the pressure delivered by the pump 12 to the first pressure.
  • the first pressure e.g., 28,000 kPa
  • Means 106 are provided for blocking flow from the second end 62 of the bore 54 past both the first relief valve 70 and the second relief valve 74 responsive to engagement of the third circuit 24 at the upstaged pressure.
  • the pilot control valve 28c is shifted upwardly which in turn shifts the main control valve 26c upwardly.
  • a solenoid actuated valve 108 is shifted rightwardly from the position shown, on operator activation of a switch.
  • the pressure in line 34c is delivered via a branch conduit 110 against a first side 112 of a two position valve 114.
  • the first relief valve 70 is likewise incapacitated. Flow can still, however, occur from the second end 62 of the bore 54 to the upstage pressure opening relief valve 80. And, when pressure reaches its upstage value (e.g., 31,000 kPa) , the upstage relief valve 80 opens, whereby the dump spool 58 opens, thereby regulating pressure in the main conduit 50 to be the upstage pressure.
  • its upstage value e.g., 31,000 kPa
  • Pressure in the conduit 122 is also supplied via a displacement control conduit 128 to a conventional pump displacement control 130. Responsive to the pressure in the displacement control conduit 128, the variable displacement pump 12 shifts to a lower displacement and thereby supplies pressurized fluid at a lower flow rate. This assures that when upstaged pressure operation, is taking place in the third circuit 24, it is taking place at a relatively slow rate so that the various structural components being moved by third circuit 24 are not strained beyond their limits.
  • a two position valve 132 is positioned in the pressure control line 38.
  • the two position valve 132 serves to assure that when the second circuit 22 is engaged, the pressure delivered by the pump 12 to the main conduit 50 is limited to the second pressure. If, for example, the first circuit 20 is engaged, the main line 50 will be limited to the first pressure (e.g., 28,000 kPa) as has been previously explained. If the pilot control valve 28b is now moved to engage the second circuit 22, pressure from the conduit 42 is applied via a branch conduit 134 against the two position valve 132, in opposition to the biasing thereof by a spring 136. The pressure in the branch conduit 134 overcomes the force of the spring 136 and forces the two position valve 132 upwardly.
  • the solenoid actuated valve 108 in combination with the two position valve 114 and various conduits as previously described, serves as means for selectively operating the third circuit 24 at an upstaged pressure which exceeds the first pressure. Further, the displacement control conduit 128 then serves as means for reducing the displacement of the pump 12, in response to the third circuit 24 being operated at the upstaged pressure. It also follows that the two position valve
  • the 114 serves as means for preventing operation of the third circuit 24 at the upstaged pressure when either the first circuit 20 or the second circuit 22 is engaged. That is, whenever there is pressure in the upstaged pressure blocking conduit 46, which corresponds to either the first circuit 20 or the second circuit 22 being enqaqed, the two position valve 114 is blocked, thus preventing upstaged operation of the third circuit 24. Furthermore, the third circuit 24 is normally operated only up to a third pressure, which is generally no greater than the aforementioned first pressure and usually no greater than the aforementioned second pressure.
  • the pilot control valve 28c motivates the main control valve 26c, which receives pressurized fluid at a pressure determined by either first relief valve 70 or second relief valve 74 in the absence of shifting of solenoid valve 108 rightwardly and shifting of main control valve 26c upwardly, to place third circuit 24 in the upstaged mode of operation. If it is desired to limit operation of the third circuit 24 to the second pressure, this can be accomplished by duplicating two position valve 132 or providing an appropriate resolver from line 32c and from conduit 42 to branch conduit 134.
  • the aforementioned and described improved hydraulic system is particularly useful with an excavator and wherein the first circuit is a track drive circuit, the second circuit is a stick control circuit and the third circuit is a boom control circuit. Further, in such an excavator the upstaged operation of the boom control circuit is normally selectable only on boom raising operation.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
PCT/US1979/000735 1979-09-17 1979-09-17 Controlled pressure upstaging and flow reduction WO1981000742A1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
JP50059080A JPS56501133A (ru) 1979-09-17 1979-09-17
PCT/US1979/000735 WO1981000742A1 (en) 1979-09-17 1979-09-17 Controlled pressure upstaging and flow reduction
CA000356034A CA1141265A (en) 1979-09-17 1980-07-11 Controlled pressure upstaging and flow reduction
EP80105575A EP0025609B1 (en) 1979-09-17 1980-09-17 Hydraulic system with selective pressure upstaging
DE8080105575T DE3063346D1 (en) 1979-09-17 1980-09-17 Hydraulic system with selective pressure upstaging

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/US1979/000735 WO1981000742A1 (en) 1979-09-17 1979-09-17 Controlled pressure upstaging and flow reduction
WOUS79/00735 1979-09-17

Publications (1)

Publication Number Publication Date
WO1981000742A1 true WO1981000742A1 (en) 1981-03-19

Family

ID=22147703

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1979/000735 WO1981000742A1 (en) 1979-09-17 1979-09-17 Controlled pressure upstaging and flow reduction

Country Status (4)

Country Link
EP (1) EP0025609B1 (ru)
JP (1) JPS56501133A (ru)
DE (1) DE3063346D1 (ru)
WO (1) WO1981000742A1 (ru)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4864822A (en) * 1987-01-23 1989-09-12 Hydromatik Gmbh Control device for a hydrostatic drive for at least two actuators
US5079919A (en) * 1989-03-30 1992-01-14 Hitachi Construction Machinery Co., Ltd. Hydraulic drive system for crawler mounted vehicle
US5323687A (en) * 1991-10-28 1994-06-28 Danfors A/S Hydraulic circuit
US5575148A (en) * 1993-11-30 1996-11-19 Hitachi Construction Machinery Co., Ltd. Hydraulic pump control system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481770A (en) * 1982-03-22 1984-11-13 Caterpillar Tractor Co. Fluid system with flow compensated torque control
DE3321484A1 (de) * 1983-06-14 1984-12-20 Linde Ag, 6200 Wiesbaden Hydraulische anlage mit zwei verbrauchern hydraulischer energie
EP0564939B1 (de) * 1992-04-04 1995-12-13 Mannesmann Rexroth AG Hydraulische Steuereinrichtung für mehrere Verbraucher

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3788401A (en) * 1972-07-17 1974-01-29 Caterpillar Tractor Co Hydraulic circuit with valve to provide semi-float control of a dozer blade
US3922855A (en) * 1971-12-13 1975-12-02 Caterpillar Tractor Co Hydraulic circuitry for an excavator
US4020862A (en) * 1973-12-15 1977-05-03 Idra-Pressen G.M.B.H. Apparatus for controlling the volume and pressure of a pressure medium in a die-casting machine
US4024797A (en) * 1975-10-28 1977-05-24 Caterpillar Tractor Co. Spring centered balanced resolver valve
US4107924A (en) * 1977-04-28 1978-08-22 Caterpillar Tractor Co. Pump upgrading system
US4123907A (en) * 1977-04-19 1978-11-07 Caterpillar Tractor Co. Hydraulic system having selective simultaneous pressure and flow control

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030623A (en) * 1971-12-13 1977-06-21 Caterpillar Tractor Co. Hydraulic circuitry for an excavator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922855A (en) * 1971-12-13 1975-12-02 Caterpillar Tractor Co Hydraulic circuitry for an excavator
US3788401A (en) * 1972-07-17 1974-01-29 Caterpillar Tractor Co Hydraulic circuit with valve to provide semi-float control of a dozer blade
US4020862A (en) * 1973-12-15 1977-05-03 Idra-Pressen G.M.B.H. Apparatus for controlling the volume and pressure of a pressure medium in a die-casting machine
US4024797A (en) * 1975-10-28 1977-05-24 Caterpillar Tractor Co. Spring centered balanced resolver valve
US4123907A (en) * 1977-04-19 1978-11-07 Caterpillar Tractor Co. Hydraulic system having selective simultaneous pressure and flow control
US4107924A (en) * 1977-04-28 1978-08-22 Caterpillar Tractor Co. Pump upgrading system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4864822A (en) * 1987-01-23 1989-09-12 Hydromatik Gmbh Control device for a hydrostatic drive for at least two actuators
US5079919A (en) * 1989-03-30 1992-01-14 Hitachi Construction Machinery Co., Ltd. Hydraulic drive system for crawler mounted vehicle
US5323687A (en) * 1991-10-28 1994-06-28 Danfors A/S Hydraulic circuit
US5575148A (en) * 1993-11-30 1996-11-19 Hitachi Construction Machinery Co., Ltd. Hydraulic pump control system

Also Published As

Publication number Publication date
EP0025609A1 (en) 1981-03-25
DE3063346D1 (en) 1983-07-07
EP0025609B1 (en) 1983-05-18
JPS56501133A (ru) 1981-08-13

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