EP0027743A1 - Control system for a hydraulic circuit including a plurality of parallel variable-delivery pumps - Google Patents

Control system for a hydraulic circuit including a plurality of parallel variable-delivery pumps Download PDF

Info

Publication number
EP0027743A1
EP0027743A1 EP19800303741 EP80303741A EP0027743A1 EP 0027743 A1 EP0027743 A1 EP 0027743A1 EP 19800303741 EP19800303741 EP 19800303741 EP 80303741 A EP80303741 A EP 80303741A EP 0027743 A1 EP0027743 A1 EP 0027743A1
Authority
EP
European Patent Office
Prior art keywords
pumps
delivery
state
maximum
pressure fluid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19800303741
Other languages
German (de)
French (fr)
Other versions
EP0027743B1 (en
Inventor
Kiyoshi Gotoda
Masayuki Eguma
Akira Asari
Masaru Takeda
Yasuhiro Nakashima
Tatsuhiko Noyori
Munenori Soejima
Masanobu Aoki
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.)
Kobe Steel Ltd
Original Assignee
Kobe Steel Ltd
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 Kobe Steel Ltd filed Critical Kobe Steel Ltd
Publication of EP0027743A1 publication Critical patent/EP0027743A1/en
Application granted granted Critical
Publication of EP0027743B1 publication Critical patent/EP0027743B1/en
Expired legal-status Critical Current

Links

Images

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
    • 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
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/30575—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve in a Wheatstone Bridge arrangement (also half bridges)
    • 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
    • F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/50518—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
    • F15B2211/505—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
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a 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
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a 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
    • F15B2211/50—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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/615—Filtering 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6336—Electronic controllers using input signals representing a state of the output member, e.g. position, speed or acceleration
    • 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
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
    • 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
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6653—Pressure control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—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
    • F15B2211/7051—Linear output members
    • F15B2211/7052—Single-acting 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
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting 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
    • 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
    • F15B2211/7107—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being mechanically linked
    • 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
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel
    • 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
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/88—Control measures for saving energy

Definitions

  • This invention relates to a control system for use in a hydraulic circuit supplying pressurized oil or fluid from a plurality of parallel-connected variable-delivery pumps to a hydraulic appliance.
  • a control system for use in a hydraulic circuit including a plurality of parallel variable-delivery pumps; said control system comprising means for bringing one of said pumps into a loaded state for delivering a required volume of pressure fluid and the other pumps into an unloaded state when the required volume of pressure fluid is less than the maximum volume of pressure fluid deliverable from one of said pumps, and for bringing one or more of said pumps into a loaded scate under its substantially maximum delivery state, one of the other pumps into some intermediate delivery state and the remaining pumps into an unloaded state when the required volume of pressure fluid exceeds the maximum deliverable from one or more pumps.
  • the invention also provides a control system for use in a hydraulic circuit including a plurality of parallel variable-delivery pumps; said control system comprising a sensor for sensing a demanded quantity of pressure fluid, means for developing control signals in dependence on the operation of the sensor and control valves and regulators for controlling the operation of the pumps in dependence on said control signals whereby when the demanded quantity of pressure fluid is less than the maximum quantity deliverable from one of the pumps, one of the pumps is brought into a loaded state to deliver the demanded quantity of pressure fluid and the other pumps are brought in an unloaded state and when the demanded quantity exceeds the maximum quantity deliverable from one of the pumps at least one of the pumps is brought into a loaded state to deliver its maximum deliverable quantity of fluid, another pump is brought into an intermediate state to deliver a quantity of fluid less than its maximum deliverable quantity of fluid and the remaining pumps are brought into an unloaded state.
  • the quantity of fluid delivered from each of the pump is controlled by the control system dynamically and according to the demanded quantity required by the appliance which may be an extrusion press.
  • the system ensures the pumps operate i.n an optimum manner to reduce energy loses and power consumption.
  • Figure 1 shows a hydraulic circuit of an extrusion press, which comprises variable -delivery pumps (11,12,13 and 14), pump driving motors (21,22,23 and 24), delivery regulators (31, 32, 33 and 34) one for each of the pumps, loading control valves (41, 42, 43 and 44) for loading and unloading the respective pumps, relief valves (45, 46, 47 and 48), direction switching solenoid valves (51, 52, 53, 54, 55 and 56), a full oil valve (57), relief valves ( 58 and 59), an extrusion press (60) having a main cylinder (61), side cylinders (62 and 63) and a stem (64), and pilot pumps (71 and 72). These hydraulic component parts are interconnected as shown in Figure 1.
  • variable-delivery pumps 11, 12, 13 and 14
  • the volume of pressure fluid e.g. oil
  • the volume of pressure fluid e.g. oil
  • programmed electric signals are fed from a control panel not shown to actuate one or more of the solenoid valves (51, 52, 53, 54, 55 and 56), thus establishing flow paths between the respective cylinders (61, 62 and 63) and the pumps or an oil reservoir and actuating the respective cylinders (61, 62 and 63)according to the control program.
  • the operation speed of the stem (64,) that is, the volume of oil supplied to each of the cylinders (61, 62 and 63) is controlled by switching on and off the loading control valves (41, 42, 43 and 44) which in turn govern the delivery of each of the respective pumps (11, 12, 13 and 14).
  • the operation speed of the stem (64) (this is referred to as "extrusion speed” hereinafter) is monitored with a sensor (81) operatively associated with a stem speed setting (80) installed on the extrusion press (6).
  • the function of the sensor is to detect the actual extrusion speed in terms of percentage wherein rated maximum speed is denoted as 100%.
  • the output of the sensor (81) is converted into an AC or DC signal and supplied to a controller (82) which in turn provides individual signals (C1, C2, C3 and C4) for the delivery regulators (31, 32, 33 and 34) and individual signals (Cl', C2', C3' and C4') for the loading control solenoid valves (41, 42, 43 and 44 in response to a previously programmed extrusion start signal.
  • a controller which in turn provides individual signals (C1, C2, C3 and C4) for the delivery regulators (31, 32, 33 and 34) and individual signals (Cl', C2', C3' and C4') for the loading control solenoid valves (41, 42, 43 and 44 in response to a previously programmed extrusion start signal.
  • the delivery regulators (31, 32, 33 and 34) are supplied with a given pilot pressure (Pa) from the pilot pump (71).
  • the respective solenoid valves (41, 42, 43 and 44) are switched on and off to load and unload the respective pumps (11, 12, 13 and 14) according to the extrusion speed or the required volume of oil for each of the cylinders (61, 62 and 63) as seen from Figure 3.
  • the solenoid valve (41) is energized to load only the one pump (11) of which the inclination is varied by the delivery regulator (31) to control its delivery output within the range of 0-100%. Ps a result, the only pump which supplies the required volume of oil and actuates the stem (64) is the pump (11). Under these circumstances the remaining solenoid valves (42, 43 and 44) are disenergized to place the corresponding pumps (12, 13 and 14) into no-load state.
  • the solenoid valves (41 and 42) are energizea to load the two pumps (11 and 12).
  • the delivery regulator (31) increases the inclination of one of the two pumps (11) to its maximum (100%) and the delivery of that pump (11) to its maximum (100%).
  • the delivery regulator (32) controls the inclination of the other pump (12) and regulates its delivery within the range of 0-100%. Accordingly, the 100% delivery pump (11;, combined with the other pump (12) which supplies the deficiency of oil, provides exactly the required volume of oil for actuation of the stem (64).
  • the solenoid valves (43 and 44) are disenergized to to unload the remaining pumps (13 and 14) and place the same into no-load state.
  • the pumps (11, 12, 13 and 14) are loaded in the numerical order in this manner (the reverse of order with a decrease in oil requirement).
  • One or more 100% delivery pumps and one supplemental pump under half-load state satisfy exactly the oil requirement, while the remaining pump or pumps are maintained under no-load state with no delivery.
  • This control method ensures up to 40% power ; saving as compared with the conventional method wherein all of the pumps are loaded at one time.
  • a particular pump is adapted to start inclining after 100% inclination of the preceding pump.
  • the particular pump may start inclining subsequent to 95% inclination of the preceding pump, for example, in order to provide smooth and continuous operation as a whole,
  • the relationship between the extrusion speed and the inclination speed is controlled to be one half of that with only one pump.
  • variable-delivery pump the volume efficiency and the overall efficiency vary in dependence on the inclination ( ⁇ ) or the delivery volume of oil delivered as shown in Figure 5 and 6.
  • ⁇ the inclination
  • the characteristic of the variable-delivery pump is that its volume efficiency amount to maximum values when it operates with its rated maximum delivery (maximum inclination).
  • the operation speed of the stem within the extrusion press is varied frequently and within a wide range so that the volume of oil supplied and the delivery of the pump are varied frequently and within a wide range.
  • the respective pumps operate less frequently with its rated maximum speed (the required volume of oil is equal to the total of the maximum deliveries of the overall pumps).
  • the present invention only a minimum number of the pumps are loaded depending upon oil requirement and the remaining pumps are unloaded, thus reducing power consumption. Moreover, only one of the loaded pumps is held in half-load state while all of the remaining pumps operate with full or 100% delivery. This leads to a substantial increase in the total efficiency of the pumps and remarkable energy-saving characteristics.
  • the motor (24) is disenergized when the pump (11) is in 100% delivery state and the pump (12) is in half-load state.
  • the motor (23) is disenergized when the delivery control signal (C2) for the pump (12) is less than 70% and energized when the same exceeds 70%.
  • the pump (13) is maintained in ro-load state.
  • the line (a) depicts power saving when the extrusion speed is 25% of the rated value, while the line (b) power saving when the extrusion speed is 50% of the rated speed. It is clear from Figure 7, that the present invention ensures 20-40% power saving in the case of the line (a) and 8-18% power saving in the case of the line (b). The lower the extrusion pressure (remarkable especially with less than 50 kg/cm )and the extrusion speed, the greater the power saving effect.
  • the present invention provides effective and power-saving actuation of the pumps.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Presses (AREA)
  • Press Drives And Press Lines (AREA)

Abstract

A hydraulic circuit includes a plurality of parallel variable-delivery pumps (11-14) for supplying pressure fluid to an appliance such as an extrusion press (60). A control system is provided to optimize the operation of the pumps. This system utilizes a sensor which senses the quantity of fluid demanded by the appliance and a controller provides control signals which vary in accordance with the sensor function. These control signals in turn control solenoid valves (41-44) and regulators (31-34) which control the individual pumps in accordance with the demanded fluid.

Description

    BACKGROUND OF THE INVENTION Field of the Art;
  • This invention relates to a control system for use in a hydraulic circuit supplying pressurized oil or fluid from a plurality of parallel-connected variable-delivery pumps to a hydraulic appliance.
    • SUMMARY OF THE INVENTION
  • According to the invention there is provided a control system for use in a hydraulic circuit including a plurality of parallel variable-delivery pumps; said control system comprising means for bringing one of said pumps into a loaded state for delivering a required volume of pressure fluid and the other pumps into an unloaded state when the required volume of pressure fluid is less than the maximum volume of pressure fluid deliverable from one of said pumps, and for bringing one or more of said pumps into a loaded scate under its substantially maximum delivery state, one of the other pumps into some intermediate delivery state and the remaining pumps into an unloaded state when the required volume of pressure fluid exceeds the maximum deliverable from one or more pumps.
  • The invention also provides a control system for use in a hydraulic circuit including a plurality of parallel variable-delivery pumps; said control system comprising a sensor for sensing a demanded quantity of pressure fluid, means for developing control signals in dependence on the operation of the sensor and control valves and regulators for controlling the operation of the pumps in dependence on said control signals whereby when the demanded quantity of pressure fluid is less than the maximum quantity deliverable from one of the pumps, one of the pumps is brought into a loaded state to deliver the demanded quantity of pressure fluid and the other pumps are brought in an unloaded state and when the demanded quantity exceeds the maximum quantity deliverable from one of the pumps at least one of the pumps is brought into a loaded state to deliver its maximum deliverable quantity of fluid, another pump is brought into an intermediate state to deliver a quantity of fluid less than its maximum deliverable quantity of fluid and the remaining pumps are brought into an unloaded state.
  • In general the quantity of fluid delivered from each of the pump is controlled by the control system dynamically and according to the demanded quantity required by the appliance which may be an extrusion press. The system ensures the pumps operate i.n an optimum manner to reduce energy loses and power consumption.
  • The invention may be understood more readily, and various other features of the invention may become apparent from consideration of the following description.
  • A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, wherein :
    • Figure 1 is a schematic circuit diagram of a hydraulic circuit for an extrusion press control system constructed in accordance with the present invention;
    • Figure 2 is a schematic electric circuit diagram showing an example of means for developing _control signals;
    • Figure 3 is a table for explaining the relationship between press extrusion speed and the loaded state of the pumps;
    • Figure 4 is a table for explaining the relationship between press extrusion speed and the inclinations of the pumps ;
    • Figure 5 is a characteristic graph showing the volume efficiency of one of the variable-delivery pumps ;
    • Figure 6 is a characteristic graph showing the overall efiiciency of one of the variable-delivery pumps; and
    • Figure 7 is a graph representing the energy-saving effect of the present invention.
    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • Figure 1 shows a hydraulic circuit of an extrusion press, which comprises variable -delivery pumps (11,12,13 and 14), pump driving motors (21,22,23 and 24), delivery regulators (31, 32, 33 and 34) one for each of the pumps, loading control valves (41, 42, 43 and 44) for loading and unloading the respective pumps, relief valves (45, 46, 47 and 48), direction switching solenoid valves (51, 52, 53, 54, 55 and 56), a full oil valve (57), relief valves ( 58 and 59), an extrusion press (60) having a main cylinder (61), side cylinders (62 and 63) and a stem (64), and pilot pumps (71 and 72). These hydraulic component parts are interconnected as shown in Figure 1.
  • In the illustrative embodiment, only the four variable-delivery pumps (11, 12, 13 and 14) are connected in parallel and the volume of pressure fluid, e.g. oil, delivered from each of the pumps is supplied to a respective cylinders (61, 62 and 63) of the extrusion press (6) to actuate the stem (64). When this occurs, programmed electric signals are fed from a control panel not shown to actuate one or more of the solenoid valves (51, 52, 53, 54, 55 and 56), thus establishing flow paths between the respective cylinders (61, 62 and 63) and the pumps or an oil reservoir and actuating the respective cylinders (61, 62 and 63)according to the control program.
  • The operation speed of the stem (64,) that is, the volume of oil supplied to each of the cylinders (61, 62 and 63) is controlled by switching on and off the loading control valves (41, 42, 43 and 44) which in turn govern the delivery of each of the respective pumps (11, 12, 13 and 14). As best shown in Figure 2, the operation speed of the stem (64) (this is referred to as "extrusion speed" hereinafter) is monitored with a sensor (81) operatively associated with a stem speed setting (80) installed on the extrusion press (6). The function of the sensor is to detect the actual extrusion speed in terms of percentage wherein rated maximum speed is denoted as 100%. The output of the sensor (81) is converted into an AC or DC signal and supplied to a controller (82) which in turn provides individual signals (C1, C2, C3 and C4) for the delivery regulators (31, 32, 33 and 34) and individual signals (Cl', C2', C3' and C4') for the loading control solenoid valves (41, 42, 43 and 44 in response to a previously programmed extrusion start signal. It is noted that the delivery regulators (31, 32, 33 and 34) are supplied with a given pilot pressure (Pa) from the pilot pump (71).
  • In order that the inclinations of the respective pumps (11, 12, 13 and 14) may control its delivery as depicted in Figure 4, the respective solenoid valves (41, 42, 43 and 44) are switched on and off to load and unload the respective pumps (11, 12, 13 and 14) according to the extrusion speed or the required volume of oil for each of the cylinders (61, 62 and 63) as seen from Figure 3.
  • In particular, when the extrusion speed is within the range from 0% to 25% of the rated maximum speed or when the volume of oil necessary for the cylinder is within the range from 0% to 25% of the total of the maximum delivery volumes of the respective pumps (11, 12, 13 and 14) (i.e., the rated maximum flow rate), the solenoid valve (41) is energized to load only the one pump (11) of which the inclination is varied by the delivery regulator (31) to control its delivery output within the range of 0-100%. Ps a result, the only pump which supplies the required volume of oil and actuates the stem (64) is the pump (11). Under these circumstances the remaining solenoid valves (42, 43 and 44) are disenergized to place the corresponding pumps (12, 13 and 14) into no-load state.
  • With the extrusion speed within the range of 25 to 50% of the rated maximum speed or the required volume of oil within the range of 25 to 50% of the total of the rated maximum delivery volumes, the solenoid valves (41 and 42) are energizea to load the two pumps (11 and 12). The delivery regulator (31) increases the inclination of one of the two pumps (11) to its maximum (100%) and the delivery of that pump (11) to its maximum (100%). The delivery regulator (32), on the other hand, controls the inclination of the other pump (12) and regulates its delivery within the range of 0-100%. Accordingly, the 100% delivery pump (11;, combined with the other pump (12) which supplies the deficiency of oil, provides exactly the required volume of oil for actuation of the stem (64). In this instance, the solenoid valves (43 and 44) are disenergized to to unload the remaining pumps (13 and 14) and place the same into no-load state.
  • Similarly, with the extrusion speed within the range of 50-75% of the rated maximum speed, two of the pumps (11 and 12) are loaded with 100% delivery and one of the remaining pumps (13) is placed into half-load state with its delivery within the range of 0-100% so as to compensate for the deficiency of oil, thus exactly the required volume of oil. The remaining one pump (14) is unloaded under these circumstances. When the extrusion speed is within the range of 75-100% of the rated maximum speed, there are three of the pumps (11,12 and 13) loaded with 100% delivery and the remaining one of the pumps (14) whose delivery is controlled within the range of 0-100% under half-load state so as to compensate for deficient oil.
  • With an increase in the required volume of oil the pumps (11, 12, 13 and 14) are loaded in the numerical order in this manner (the reverse of order with a decrease in oil requirement). One or more 100% delivery pumps and one supplemental pump under half-load state satisfy exactly the oil requirement, while the remaining pump or pumps are maintained under no-load state with no delivery. This control method ensures up to 40% power ; saving as compared with the conventional method wherein all of the pumps are loaded at one time.
  • In Figure 4, a particular pump is adapted to start inclining after 100% inclination of the preceding pump. However, in the case where speed should vary during one operation stroke, the particular pump may start inclining subsequent to 95% inclination of the preceding pump, for example, in order to provide smooth and continuous operation as a whole, In this case, the relationship between the extrusion speed and the inclination speed is controlled to be one half of that with only one pump.
  • For the variable-delivery pump the volume efficiency and the overall efficiency vary in dependence on the inclination (α) or the delivery volume of oil delivered as shown in Figure 5 and 6. The characteristic of the variable-delivery pump is that its volume efficiency amount to maximum values when it operates with its rated maximum delivery (maximum inclination).
  • As discussed with regard to the illustrative embodiment, the operation speed of the stem within the extrusion press is varied frequently and within a wide range so that the volume of oil supplied and the delivery of the pump are varied frequently and within a wide range. As a result, the respective pumps operate less frequently with its rated maximum speed (the required volume of oil is equal to the total of the maximum deliveries of the overall pumps).
  • In the past, all of the pumps were loaded at one time according to the extrusion speed (the required volume of oil) to supply constantly the same volume of pressurized oil so as to supply exactly the required volume of oil while the inclinations of all of the pumps in the extrusion press were controlled to the same extent. All of the pumps were therefore held in half-load state with poor volume efficiency a.nd poor overall efficiency at all times. In other words, all of the pu.nps operated with low efficiency and consumed wastefully power or energy.
  • According to the present invention, only a minimum number of the pumps are loaded depending upon oil requirement and the remaining pumps are unloaded, thus reducing power consumption. Moreover, only one of the loaded pumps is held in half-load state while all of the remaining pumps operate with full or 100% delivery. This leads to a substantial increase in the total efficiency of the pumps and remarkable energy-saving characteristics.
  • Further energy-saving effected is ensured if the hydraulic circuit is unloaded in conjunction with the unloaded pumps and the drive motors (21, 22, 23 and 24) are disenergized. Under the circumstance it is easy to incorporate an automatic sequence as follows : For example, the motor (24) is disenergized when the pump (11) is in 100% delivery state and the pump (12) is in half-load state. The motor (23) is disenergized when the delivery control signal (C2) for the pump (12) is less than 70% and energized when the same exceeds 70%. The pump (13) is maintained in ro-load state.
  • Assume now that the four main pumps are used and the extrusion speed is selected at 25% and 50% of the rated speed. Power-saving effect can be evaluated and compared as follows . In the conventional pump uniform control method all of the pumps are loaded with 25% delivery and 50% delivery, respectively, whereas according to the present invention only one of the pumps is energized with 100% delivery and the remaining three pumps are unloaded when the extrusion speed is desired to be 25% of the rated speed. Moreover, when the extrusion is 50% of the rated speed, two of the pumps are loaded under 100% delivery state and the remaining two pumps are unloaded. Under these circumstances the present invention exhibits outstanding energy-effects as depicted in Figure 7. Figure 7 shows estimated ratios of percentages of power saving by the present invention wherein power saving by the conventional method is 100%. The line (a) depicts power saving when the extrusion speed is 25% of the rated value, while the line (b) power saving when the extrusion speed is 50% of the rated speed. It is clear from Figure 7, that the present invention ensures 20-40% power saving in the case of the line (a) and 8-18% power saving in the case of the line (b). The lower the extrusion pressure (remarkable especially with less than 50 kg/cm )and the extrusion speed, the greater the power saving effect.
  • As noted earlier, the present invention provides effective and power-saving actuation of the pumps.
  • Whereas in the above illustrated embodiment of the present invention the power-saving effect is ensured in the extrusion press wherein the extrusion speed (the required volume of oil) is varied frequently and within a wide range, it is obvious that the concept of the present invention is equally applicable to any hydraulic actuators including an extrusion press.

Claims (2)

1. A control system for use in a hydraulic circuit including a plurality of parallel variable-delivery pumps; said control system comprising means for bringing one of said pumps into a loaded state for delivering a required volume of pressure fluid and the other pumps into an unloaded state when the required volume of pressure fluid is less than the maximum volume of pressure fluid deliverable from one of said pumps, and for bringing one or more of said pumps into a loaded state under its substantially maximum delivery state, one of the other pumps into some intermediate delivery state and the remaining pumps into an unloaded state when the required volume of pressure fluid exceeds the maximum volume deliverable from one or more pumps.
2. A control system for use in a hydraulic circuit including P plurality of parallel variable-delivery pumps; said control system comprising a sensor for sensing a demanded quantity of pressure fluid, means for developing control signals in dependence on the operation of the sensor and control valves and regulators for controlling the operation of the pumps in dependence on said control signals whereby when the demanded quantity of pressure fluid is less than the maximum quantity deliverable from one of the pumps , one of the pumps is brought into a loaded state to deliver the demanded quantity of pressure fluid and the other pumps are brought in an unloaded state and when the demanded quantity exceeds the maximum quantify deliverable from one of the pumps at least one of the pumps is brought into a loaded state to deliver its maxin.um deliverable quantity of fluid, another pump is brought into an intermediate state to deliver a quantity of fluid less than its maximum deliverable quantity of fluid and the remaining pumps are brought into an unloaded state.
EP19800303741 1979-10-22 1980-10-22 Control system for a hydraulic circuit including a plurality of parallel variable-delivery pumps Expired EP0027743B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP13661879A JPS5659005A (en) 1979-10-22 1979-10-22 Controller for hydraulic circuit including plural variable-capacity pumps in parallel
JP136618/79 1979-10-22

Publications (2)

Publication Number Publication Date
EP0027743A1 true EP0027743A1 (en) 1981-04-29
EP0027743B1 EP0027743B1 (en) 1985-05-15

Family

ID=15179505

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19800303741 Expired EP0027743B1 (en) 1979-10-22 1980-10-22 Control system for a hydraulic circuit including a plurality of parallel variable-delivery pumps

Country Status (3)

Country Link
EP (1) EP0027743B1 (en)
JP (1) JPS5659005A (en)
DE (1) DE3070650D1 (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3614967A1 (en) * 1986-05-02 1987-11-05 Paals Packpressen Fabrik Gmbh Baling press
US5128335A (en) * 1990-10-15 1992-07-07 Merck & Co., Inc. 2-heteroarylphenyl-carbapenem antibacterial agents
US6128900A (en) * 1998-01-28 2000-10-10 Case Corporation Hydraulic fluid supply system
AT411784B (en) * 2000-05-03 2004-05-25 Weber Walter CONTROL DEVICE FOR DOUBLE-ACTING HYDRAULIC WORKING CYLINDERS
WO2013167111A1 (en) * 2012-05-10 2013-11-14 Sms Meer Gmbh Hydraulic extrusion press and method for operating a hydraulic extrusion press
US20140096581A1 (en) * 2011-06-15 2014-04-10 Ube Machinery Corporation, Ltd. Extrusion press
US9506480B2 (en) 2013-04-11 2016-11-29 Hitachi Construction Machinery Co., Ltd. Apparatus for driving work machine
CN111572083A (en) * 2020-04-17 2020-08-25 江苏国力锻压机床有限公司 Hydraulic press for glass fiber reinforced plastic products

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5821505U (en) * 1981-08-04 1983-02-09 富士レビオ株式会社 bottle
JPS58174704A (en) * 1982-04-07 1983-10-13 Uchida Yuatsu Kiki Kogyo Kk Flow control method in confluence circuit
JPS60208605A (en) * 1984-03-31 1985-10-21 Ishikawajima Harima Heavy Ind Co Ltd On-deck machinery control equipment for ship
JPS60245806A (en) * 1984-05-18 1985-12-05 Nissei Plastics Ind Co Converging circuit
JPS60245805A (en) * 1984-05-18 1985-12-05 Nissei Plastics Ind Co Converging circuit
JPS6353002U (en) * 1986-09-24 1988-04-09
DE3901475C2 (en) * 1989-01-19 1994-07-14 Danfoss As Fluid controlled servo assembly
JPH0752390Y2 (en) * 1989-11-27 1995-11-29 油研工業株式会社 Hydraulic supply device
JP2580999Y2 (en) * 1990-10-30 1998-09-17 三菱重工業株式会社 Injection molding machine having hydraulic pressure supply device
US6004264A (en) 1994-07-04 1999-12-21 Asahi Kogaku Kogyo Kabushiki Kaisha Portable endoscope system
JP2010164086A (en) * 2009-01-13 2010-07-29 Isuzu Motors Ltd Plunger mechanism for combining multiple thrust
JP2011224644A (en) * 2010-04-23 2011-11-10 Ube Machinery Corporation Ltd Extrusion press device
JP5846483B2 (en) * 2011-10-25 2016-01-20 宇部興産機械株式会社 Extrusion press control method
JP5769859B1 (en) * 2014-11-03 2015-08-26 日本エアロフォージ株式会社 Hydraulic forging press apparatus and control method thereof
WO2017075411A1 (en) 2015-10-28 2017-05-04 Acera LLC Embeddable module for high output led
JP6704716B2 (en) * 2015-11-26 2020-06-03 株式会社モリタ環境テック Cutting processing apparatus and method of operating cutting processing apparatus
EP3311997A1 (en) * 2016-10-18 2018-04-25 Automation, Press and Tooling, A.P. & T AB Servo hydraulic press
JP6834508B2 (en) * 2017-01-17 2021-02-24 宇部興産機械株式会社 Main ram extrusion speed control method and extrusion press in extrusion press
JP7375603B2 (en) * 2020-02-20 2023-11-08 Ｕｂｅマシナリー株式会社 extrusion press equipment

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2811838A (en) * 1954-06-15 1957-11-05 American Steel Foundries Hydraulic press circuit
US2947317A (en) * 1953-06-12 1960-08-02 Electraulic Presses Ltd Unloading valves for hydraulic pumps
FR1410250A (en) * 1964-06-16 1965-09-10 Compteurs Comp D Automatic control device of a pumping station
US3744932A (en) * 1971-04-30 1973-07-10 Prevett Ass Inc Automatic sequence control system for pump motors and the like

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5091010A (en) * 1973-12-17 1975-07-21
JPS526890A (en) * 1975-07-07 1977-01-19 Hitachi Ltd Speed control device for an apparatus driven by oil pressure
JPS5364241A (en) * 1976-11-19 1978-06-08 Denki Kagaku Kogyo Kk Adhesive compositions
JPS5432806U (en) * 1977-08-08 1979-03-03

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2947317A (en) * 1953-06-12 1960-08-02 Electraulic Presses Ltd Unloading valves for hydraulic pumps
US2811838A (en) * 1954-06-15 1957-11-05 American Steel Foundries Hydraulic press circuit
FR1410250A (en) * 1964-06-16 1965-09-10 Compteurs Comp D Automatic control device of a pumping station
US3744932A (en) * 1971-04-30 1973-07-10 Prevett Ass Inc Automatic sequence control system for pump motors and the like

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3614967A1 (en) * 1986-05-02 1987-11-05 Paals Packpressen Fabrik Gmbh Baling press
US5128335A (en) * 1990-10-15 1992-07-07 Merck & Co., Inc. 2-heteroarylphenyl-carbapenem antibacterial agents
US6128900A (en) * 1998-01-28 2000-10-10 Case Corporation Hydraulic fluid supply system
AT411784B (en) * 2000-05-03 2004-05-25 Weber Walter CONTROL DEVICE FOR DOUBLE-ACTING HYDRAULIC WORKING CYLINDERS
US20140096581A1 (en) * 2011-06-15 2014-04-10 Ube Machinery Corporation, Ltd. Extrusion press
US9643225B2 (en) * 2011-06-15 2017-05-09 Ube Machinery Corporation, Ltd. Extrusion press
WO2013167111A1 (en) * 2012-05-10 2013-11-14 Sms Meer Gmbh Hydraulic extrusion press and method for operating a hydraulic extrusion press
CN104428077A (en) * 2012-05-10 2015-03-18 Sms米尔股份有限公司 Hydraulic extrusion press and method for operating a hydraulic extrusion press
US20150090132A1 (en) * 2012-05-10 2015-04-02 Sms Meer Gmbh Hydraulic extrusion press and method for operating a hydraulic extrusion press
US11407192B2 (en) 2012-05-10 2022-08-09 Sms Group Gmbh Hydraulic extrusion press and method for operating a hydraulic extrusion press
US9506480B2 (en) 2013-04-11 2016-11-29 Hitachi Construction Machinery Co., Ltd. Apparatus for driving work machine
CN111572083A (en) * 2020-04-17 2020-08-25 江苏国力锻压机床有限公司 Hydraulic press for glass fiber reinforced plastic products

Also Published As

Publication number Publication date
JPH0258482B2 (en) 1990-12-07
JPS5659005A (en) 1981-05-22
EP0027743B1 (en) 1985-05-15
DE3070650D1 (en) 1985-06-20

Similar Documents

Publication Publication Date Title
EP0027743A1 (en) Control system for a hydraulic circuit including a plurality of parallel variable-delivery pumps
EP0362409A4 (en) Hydraulic driving unit
CN112249985A (en) Potential energy recycling system of combined electric forklift
CN108383039B (en) A kind of energy-saving stepping type lifter structure hydraulic control system
CN108302073A (en) A kind of automobile-used impeller rotating hydraulic system of sand throwing fire extinguishing
CN213679681U (en) Potential energy recycling system of combined electric forklift
CN110953197B (en) Power control hydraulic system and crane
JPH06105075B2 (en) Output controller for hydraulic pump
KR20070068598A (en) Apparatus for controlling power of hydraulic pump in a wheel type excavator
CN107725504B (en) Hydraulic system capable of providing proper performance for load and hydraulic control method
US6712043B2 (en) Actuating fluid control system
CN112879391B (en) Oil supplementing device and closed system
JP2001263304A (en) Fluid pressure circuit device
CN211765848U (en) Emergency steering hydraulic system and steering system of underground carry scraper
CN113928981A (en) Engineering vehicle and hydraulic driving system thereof
JPH0210802Y2 (en)
KR100953807B1 (en) Method of controlling power of hydraulic pump in an excavator and apparatus using the same
CN217502118U (en) Device for maintaining outlet pressure of electric control heavy-load open pump
CN211039209U (en) Overflow valve of manual loading unloading
US20240183352A1 (en) Variable displacement pumps with fixed and active displacement control modes
JPS6215500Y2 (en)
JP2548204Y2 (en) Hydraulic drive
JPH06117410A (en) Oil pressure circuit for construction machine
CN217462693U (en) Hydraulic system with multiple pressure outputs and engineering machinery comprising same
CN115784022A (en) Auxiliary hydraulic system of mobile crawler crane and control method thereof

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

AK Designated contracting states

Designated state(s): CH DE GB

17P Request for examination filed

Effective date: 19810312

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): CH DE GB LI

REF Corresponds to:

Ref document number: 3070650

Country of ref document: DE

Date of ref document: 19850620

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: 19961014

Year of fee payment: 17

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

Ref country code: DE

Payment date: 19961025

Year of fee payment: 17

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

Ref country code: CH

Payment date: 19961104

Year of fee payment: 17

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

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19971022

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

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19971031

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19971031

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

Effective date: 19971022

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

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

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19980701