EP0961035A1 - Machine à entraínement hydraulique - Google Patents

Machine à entraínement hydraulique Download PDF

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Publication number
EP0961035A1
EP0961035A1 EP98304133A EP98304133A EP0961035A1 EP 0961035 A1 EP0961035 A1 EP 0961035A1 EP 98304133 A EP98304133 A EP 98304133A EP 98304133 A EP98304133 A EP 98304133A EP 0961035 A1 EP0961035 A1 EP 0961035A1
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EP
European Patent Office
Prior art keywords
flow
machine
motor
hydraulic
hydraulically operated
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.)
Withdrawn
Application number
EP98304133A
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German (de)
English (en)
Inventor
Prakash Ratnaparkhi
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to EP98304133A priority Critical patent/EP0961035A1/fr
Publication of EP0961035A1 publication Critical patent/EP0961035A1/fr
Withdrawn legal-status Critical Current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
    • 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
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
    • 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
    • F15B2211/20507—Type of prime mover
    • F15B2211/20515—Electric motor
    • 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
    • F15B2211/255—Flow control functions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/426—Flow 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
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/632—Electronic controllers using input signals representing a flow rate
    • 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
    • F15B2211/632—Electronic controllers using input signals representing a flow rate
    • F15B2211/6326—Electronic controllers using input signals representing a flow rate the flow rate being an output member flow rate
    • 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
    • F15B2211/634—Electronic controllers using input signals representing a state of 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
    • F15B2211/665—Methods of control using electronic components
    • 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
    • F15B2211/6654—Flow rate 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6656—Closed loop control, i.e. control using feedback

Definitions

  • the present invention relates to hydraulic operated machines, particularly plastic injection moulding machines using hydraulic systems for its movements such as clamping and injection.
  • This invention still particularly , relates to a method for attenuating the energy required, in motor driven hydraulically operated machines, typically injection moulding machines.
  • FIG. 1 A scheme of a typical hydraulically operated injection moulding machine is illustrated in Figure 1 of the accompanying drawings.
  • the machine 100 there is a hydraulic tank T which contains hydraulic fluid.
  • a pump P driven by motor M is connected to the tank T and the outlet of the pump P is connected through differential distributor blocks to various hydraulic valves and elements defined in the hydraulic circuit block H of the machine 100. Only for ease of representation the hydraulic element is shown separate from the machine 100 .
  • the total flow TF of pressurized hydraulic fluid is supplied by the pump P to the hydraulic elements H and only the demanded flow DF is supplied to the machine 100 and the excess flow BF is bypassed to the hydraulic tank T via relief valves. Since the electric supply to the machine is continuous, the motor runs at full rpm and generates pressurized hydraulic fluid flow.
  • the various hydraulic elements in the block H require a predetermined flow of pressurized fluid through them any flow in excess of the demand for the various elements generated by the pump P and flowing through the block H is by-passed via the bypass flow BF and collected and returned to the tank T. This bypassed fluid varies upon the operation taking place in the machine 100. Thus different quantities of hydraulic fluid are bypassed during the clamping, injection or cooling operations.
  • Jones U.S. Patent No.4,904,913
  • a motor control system for a plastic forming machine which includes an interface circuit and a phase inverter for sensing the individual operations steps of the machine, thereby producing a time stream of voltage levels each of which are representative of machine functions during such operation steps and thereby varying the speed of the motor through a manually set potentiometer.
  • a major disadvantage of this arrangement is that the output driving signals to adjust the speed of the motor are taken from the machine controller making such an arrangement highly inflexible and impractical for machines of different makes.
  • the scheme envisaged is extremely cumbersome as a large number of signals need to be derived from the control panel and the motor speeds have to be adjusted manually making the whole system cumbersome and inaccurate.
  • Hertzer discloses a machine incorporating a variable speed motor, preferably a DC brushless motor.
  • the machine controller outputs driving signals to adjust the speed of the motor so that the flow delivered by the pump substantially matches the hydraulic demand imposed during each phase of the machine operation cycle.
  • the values of the motor driving signals are are calculated so that the motor/pump combination is operated at or near the maximum efficiency except when the pump control varies the displacement of the pump to effect pressure or flow compensation.
  • the output of the pump can be connected to an accumulator by way of a check valve.
  • the motor control signals which eventually control the flow of the pressurized hydraulic fluid to the machine is in accordance with the pressure signal from the said controller.
  • This scheme has a fundamental limitation because the signals do not truly represent the flow required by the machine as they are based on pressure signals from the controller and are not signals based on the actual flow of the hydraulic fluid.
  • the requirement of the accumulator and check valve makes the whole system costly, bulky and inconvenient.
  • the motor speed is controlled electronically the aim being to minimise the hydraulic fluid collected in the bypass flow in the system and regulate the flow of bypassed fluid around a preset flow rate to give maximum energy saving without significantly affecting the performance of the machine.
  • a hydraulically operated machine typically a plastic injection moulding machine having
  • a characteristic feature of this machine is that the motor speed control signal is proportional to the flow rate and not to the pressure of the hydraulic fluid and is continuously variable in response to hydraulic fluid needs of the various elements of the machine and is not in the form of a train of pulses.
  • the speed control system for the motor is such that a preset minimum flow is always maintained to meet transient flow demand.
  • the motor is an A.C. induction motor or a D.C. brushless motor.
  • an electrically operated proportional flow control valve is mounted between the pump supplying hydraulic fluid to the hydraulic circuit of the machine and the dynamic signal is derived from the signals given to the valve.
  • the control of the motor speed is achieved in a manner that the electrical signal given to the Flow Proportional Valve is monitored, this signal being in proportion to the flow required (which in turn gives the desired speed of the hydraulic elements like Hydraulic Piston at that moment).
  • Flow Proportional Valve signal can be measured by introducing a small resistance in series and tapping the voltage across it.
  • any of known technique may be used such as for example Vector Control (Close loop or Open loop), Variable Frequency Drives.
  • a flowmeter is connected in line with the bypassed flow from the hydraulic circuit and the dynamic signal is derived from signals obtained from the flowmeter.
  • variable speed controller is a voltage to frequency ratio controller or a vector flux controller.
  • variable speed controller and the circuitry for generating and supplying the dynamic signal is retrofitted to a conventional machine to evolve the machine in accordance with this invention.
  • an energy saving device in accordance with this invention is indicated generally by the reference numeral 10.
  • the motor driving the system is indicated by the reference numeral M.
  • the motor drives a pump P which inturn controls hydraulic elements H of the system connected to the output of the pump P .
  • the motor M is supplied current through a suitable electronic motor speed controller SC which receives an electrical signal I which varies depending upon the bypassed/ demanded flow (BF/DF) of the system derived through the signal processing circuit SPC.
  • the motor rpm varies in proportion to the control signal I and consequently the flow of hydraulic fluid from the pump to the hydraulic block H will vary.
  • the idea is to arrive at an optimum signal I for which the bypassed flow BF is minimum for a given state of the machine 100.
  • the flow to the hydraulic block H can be continuously regulated by regulating the signal I .
  • the variance in the signal I can be achieved by various techniques and various schemes for this purpose are shown in Figures 3 and 4.
  • the signal I2 given to the said valve V is sensed and an electric control signal is derived which is in turn fed to the electronic motor speed controller SC as I which drives the motor connected to the hydraulic pump P, thus reducing the flow of bypassed fluid BF around a predetermined preset rate.
  • a typical technique of deriving a signal is shown, whereby a current sensor CS in series with the valve coil CO is introduced.
  • the voltage developed across the current sensor is further processed by a signal processing circuit SPC to derive the requisite control signal I for the speed controller SC.
  • Alternatively other techniques to sense the voltage across the coil of the valve V or to measure the net movement of the controlling elements (spool) (not shown) of the valve V can also be used to derive the required control signal.
  • FIG. 4 Another scheme is shown in Figure 4 in which the total bypassed flow BF generated by the hydraulic circuit H is made to pass through a flowmeter FM which generates an electrical signal I3 proportional to the flow of the bypassed flow BF. Since the electrical signal is proportional to the quantity of fluid bypassed by the hydraulic circuit H, it is further processed by the signal processing circuit SPC and a control signal I is again derived which is fed to the motor speed controller SC which in turn controls the rpm of the motor M and therefore the total flow TF from the pump P, again reducing the bypassed flow BF to at or near the predetermined rate.
  • the arrangement in accordance with this invention does not require prior knowledge of the motor controller and the signal values at various points of the machine the arrangement can be built universally into any hydraulically operated machine or can be used as a retrofit to an existing machine.
  • the electronic motor speed controller SC must be such that the transient response of the controller SC matches the demand of the hydraulic circuit H of the machine 100.
  • Such speed controller include a voltage to frequency ratio control V ⁇ F controller a vector flux controller or a built in device in the motor itself to make it a multispeed motor.
  • a typical injection moulding machine for moulding polypropylene articles was tested with the arrangement in accordance with this invention:
  • the cycle time for forming an article with clamping force of 140 tonnes was 27.5 seconds in the machine without the arrangement of this invention with the arrangement retrofitted onto it the cycle time was 27.4 seconds.
  • the power consumed per hour was 10 KWHr in the standard machine and 4.8 KWHr in the machine in accordance with this invention.
  • the power saving was in the region of 52%.
  • the maximum excess flow of hydraulic fluid during idle time was 25 GPM which was only 5 GPM in the machine in accordance with this invention.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Fluid-Pressure Circuits (AREA)
EP98304133A 1998-05-26 1998-05-26 Machine à entraínement hydraulique Withdrawn EP0961035A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP98304133A EP0961035A1 (fr) 1998-05-26 1998-05-26 Machine à entraínement hydraulique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP98304133A EP0961035A1 (fr) 1998-05-26 1998-05-26 Machine à entraínement hydraulique

Publications (1)

Publication Number Publication Date
EP0961035A1 true EP0961035A1 (fr) 1999-12-01

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Family Applications (1)

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EP98304133A Withdrawn EP0961035A1 (fr) 1998-05-26 1998-05-26 Machine à entraínement hydraulique

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012143938A2 (fr) 2011-04-11 2012-10-26 Mehta Piyush A Système de conservation d'énergie pour machine hydraulique
FR3049995A1 (fr) * 2016-04-12 2017-10-13 Kuhn-Audureau Sa Dispositif de gestion de la distribution hydraulique d'un verin

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777492A (en) * 1971-02-17 1973-12-11 Dowty Technical Dev Ltd Hydraulic apparatus including variable delivery pumps
US3914939A (en) * 1973-07-11 1975-10-28 Case Co J I Pressure compensated pump
US4904913A (en) 1988-07-18 1990-02-27 Power Saving Devices, Inc. Motor control system for a plastic forming machine
US5052909A (en) 1990-01-19 1991-10-01 Cincinnati Milacron Inc. Energy-conserving injection molding machine
EP0644335A1 (fr) * 1993-03-23 1995-03-22 Hitachi Construction Machinery Co., Ltd. Moteur hydraulique pour engin de chantier hydraulique
US5580585A (en) * 1993-10-18 1996-12-03 Battenfeld Gmbh Hydraulic operational system for an injection molding machine

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777492A (en) * 1971-02-17 1973-12-11 Dowty Technical Dev Ltd Hydraulic apparatus including variable delivery pumps
US3914939A (en) * 1973-07-11 1975-10-28 Case Co J I Pressure compensated pump
US4904913A (en) 1988-07-18 1990-02-27 Power Saving Devices, Inc. Motor control system for a plastic forming machine
US4904913B1 (en) 1988-07-18 1996-06-18 Power Saving Devices Inc Motor control system for a plastic forming machine
US4904913B2 (en) 1988-07-18 1998-06-09 Power Saving Devices Inc Motor control system for a plastic forming machine
US5052909A (en) 1990-01-19 1991-10-01 Cincinnati Milacron Inc. Energy-conserving injection molding machine
EP0644335A1 (fr) * 1993-03-23 1995-03-22 Hitachi Construction Machinery Co., Ltd. Moteur hydraulique pour engin de chantier hydraulique
US5580585A (en) * 1993-10-18 1996-12-03 Battenfeld Gmbh Hydraulic operational system for an injection molding machine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
MURRENHOFF H: "ENTWICKLUNGSTRENDS IN DER FLUIDTECHNIK TEIL 1: KOMPONENTEN UND FLUIDTECHNISCHE ANTRIEBE", KONSTRUKTION, vol. 48, no. 11, 1996, pages 347 - 356, XP000195426 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012143938A2 (fr) 2011-04-11 2012-10-26 Mehta Piyush A Système de conservation d'énergie pour machine hydraulique
WO2012143938A3 (fr) * 2011-04-11 2013-03-21 Mehta Piyush A Système de conservation d'énergie pour machine hydraulique
FR3049995A1 (fr) * 2016-04-12 2017-10-13 Kuhn-Audureau Sa Dispositif de gestion de la distribution hydraulique d'un verin

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