US3744243A - Control system - Google Patents

Control system Download PDF

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Publication number
US3744243A
US3744243A US00103476A US3744243DA US3744243A US 3744243 A US3744243 A US 3744243A US 00103476 A US00103476 A US 00103476A US 3744243D A US3744243D A US 3744243DA US 3744243 A US3744243 A US 3744243A
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United States
Prior art keywords
pump
pressure
motor
commensurate
signal
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Expired - Lifetime
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US00103476A
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English (en)
Inventor
J Faisandier
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APPLIC DES MACHINES MATRICES S
SOC D APPLICATIONS DES MACHINES MATRICES FR
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APPLIC DES MACHINES MATRICES S
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    • 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
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • F15B21/087—Control strategy, e.g. with block diagram
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/46—Automatic regulation in accordance with output requirements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/46—Automatic regulation in accordance with output requirements
    • F16H61/472—Automatic regulation in accordance with output requirements for achieving a target output torque

Definitions

  • the present invention is particularly well suited for safely controlling the operation of a fixed cylinder capacity hydraulic motor having a variable delivery pump associated therewith.
  • the cylinder capacity of the pump is regulated or adjusted by an auxiliary power cylinder which is, in turn, controlled by an electrically operated servovalve.
  • Power for the solenoid of the servovalve will typically be provided by an electronic control amplifier.
  • a comparator synchro may be operatively connected to the motor and the voltage developed by the synchro will be compared with a command voltage to generate an error signal which is fed to the control amplifier.
  • a pressure sensor is inserted in each of the hydraulic lines which couple the variable capacity pump to the associated motor.
  • These pressure sensors which preferably are of the threshold type, provide or generate feedback voltages which are returned to the electronic circuitry which generates the control signal for the pump servovalve solenoid.
  • a parameter commensurate with pump cylinder'capacity is also sensed and a signal proportional thereto may also be fed back to the input of the control signal generating circuitry.
  • the feedback signals and a command signal are combined in the servovalve control circuitry and a valve control signal is generated which will appropriately vary pump cylinder capacity if the pressure in one or the other of the fluid supply lines between the pump and motor exceeds a predetermined critical value.
  • the present invention develops a feedback signal proportional to pressure for the purpose of power limitation of the hydraulic control circuit.
  • Performance of the invention may be enhanced if the pump is driven by an electric motor selected on the basis of minimum power requirements.
  • the product of pump power and capacity will be a constant.
  • the return of a signal commensurate with the product of power and capacity as an input to the servovalve control amplifier will result in a reduction in motor speed if the product exceeds the critical or design value.
  • pump drive motor current may be sensed as the regulating variable and employed in the same manner as hydraulic loop pressure to generate a signal which will be employed to reduce the speed of the motor when a critical value of pump drive motor current, and thus load on the hydraulic motor, is exceeded.
  • FIG. 1 is a schematic diagram of a first embodiment of the present invention
  • FIG. 2 is a schematic diagram of a second embodiment of the invention, the embodiment of FIG. 2 being a modification of the FIG. 1 embodiment;
  • FIG. 3 is a schematic diagram of a third embodiment of the present invention, the embodiment of FIG. 3 employing an alternating current motor to drive the hydraulic pump;
  • FIG. 4 is a schematic diagram of a modification of the embodiment of FIG. 3, the embodiment of FIG. 4 employing a direct current motor;
  • FIG. 5 is a schematic diagram of a further embodiment of the present invention.
  • FIG. 1 a hydraulic motor is indicated at 1.
  • Motor 1 is supplied with driving fluid from a variable capacity pump 2.
  • the means by which the capacity of pump 2 may be varied is indicated schematically by lever 3 which forms an angle a with a reference direction.
  • the control of the capacity of pump 2; that is, the positioning of lever 3; is accomplished by means of a double-acting cylinder indicated schematically at 4.
  • the position of the piston in cylinder 4 is controlled by a solenoid operated servovalve S.
  • the solenoid of valve 5 being indicated at 6.
  • Control current for solenoid 6 is provided by amplifier 7 and delivered to the solenoid via conductor 8'.
  • Control amplifier 7 has a plurality of input signals applied thereto.
  • a command signal for example as developed across a potentiometer, is applied to conductor 8 thence delivered to amplifier 7.
  • Feedback voltages are applied to junctions 10 and 20 and thence delivered to the input of amplifier 7.
  • the wiper arm of a potentiometer 9 is mechanically coupled to the lever 3 and thus a signal commensurate with the capacity of pump 2 is developed and fed back to amplifier 7 via junction 10. Signals commensurate with the pressure in hydraulic lines 12 and 13, which complete the fluid circuit between the motor 1 and pump 2, are also generated and delivered, in the manner to be described below, to the input of amplifier 7 via junction 20.
  • a by-pass valve 21 may be connected between lines 12 and 13.
  • By-pass valve 21 is normally closed and will open when the difference in pressure between lines 12 and 13 attains a predetermined critical value.
  • potentiometer 22 The wiper arm of potentiometer 22 is operatively connected to lever 3 and thus a second signal commensurate with the angle a is developed.
  • the potentiometer 22 is shunt-fed from conductor 13 and thus a voltage commensurate with the pressure in hydraulic line 12 is applied across the potentiometer.
  • a signal on the wiper arm 23 of potentiometer 22 will, accordingly, be a voltage which is proportional to Pa
  • This signal is delivered via conductor 25 to a voltage sensitive threshold device 26.
  • Device 26 will be adjustable so as to provide an output signal to amplifier 27 when the critical value of the product P a is exceeded.
  • Amplifier 27 may also perform a filtering function and additional threshold devices 28 and 29 and associated amplifiers 30 and 31 may be inserted in conductors 18 and 19 in place of filters 18' and 19'.
  • FIG. 3 operates with a unidirectional motor driven by pump 2.
  • Pump 2 is, in turn, driven by a three-phase, alternating current motor 32.
  • One of the supply lines 33 for three-phase motor 32 is provided with acurrent transformer 34.
  • the current induced in the secondary winding of transformer 34 is sensed by a threshold device 35.
  • the output of device 35 is applied to preamplifier 36.
  • the output of the preamplifier 36 may be applied to a rectifier device 38' and the output of rectifier 38 will be passed through a filter and limiter circuit 38".
  • the output of filter 38" will be a voltage commensurate with the current being drawn by driving motor 32 and this voltage will be combined, at junction 39, with the command signal 38.
  • the combined signals from junction point 39 are delivered, via junction 41, to power amplifier 37 which is equivalent to amplifier 7 of the embodiment of FIGS. 1 and 2.
  • Amplifier 37 provides control current for the solenoid operated servovalve 40.
  • a feedback signal commensurate with the angle a of lever 3 is also applied to the input of amplifier 37 via junction 41.
  • FIG. 4 is similar to that of FIG. 3 with the exception that alternating current motor 32 has been replaced by a direct current motor 42. Since it is not possible to employ a current transformer, such as transformer 3d of FIG. 3, with d.c. motor 42, amplifier 43 is employed to sense the current drawn by motor 42. It is to be understood that there are numerous commercially available devices which may be employed to sense the current being drawn by dc. motor.
  • the output of amplifier 43 is applied to a threshold device 44 and, if necessary, thereafter to a modulator 44'.
  • the output of device 44 or modulator 44 is combined with the command signal 38 and thereafter ap plied to power amplifier 37.
  • the feedback signal a is also applied to amplifier 37 via junction 41.
  • FIGS. 3 and 4 may be employed only with a unidirectional motor. Restated, if pump 2 is allowed to rotate in both directions, the reduction of speed which would be produced for rotation in one direction would provide a signal which would result in an increase of speed when the pump was rotated in the opposite direction. This, of course, is precisely that opposite result from that which is desired.
  • FIG. 5 illustrates a modification which may be made to the embodiments of FIGS. 3 and 4 in order to permit operation of the pump and its driving motor in either direction.
  • the current transformer 34 and other circuit elements upstream of threshold device 35 of FIG. 3 have not been depicted in FIG. 5 since such circuit elements are in no way modified.
  • the output of preamplifier 36 is delivered to parallel circuits 45 and 46.
  • An inverter circuit is included in circuit 46 and a relay means 47 is employed to connect the appropriate one of the two parallel circuits to amplifier 36.
  • the relay 47 will be in the position shown if a is positive and in the opposite position if a is negative.
  • switch 47 The change over or operation of switch 47 is achieved by providing, along the line which supplies the feedback proportional to a to junction 41, contacts (not illustrated) which are adapted to excite the coil or coils of the relay 47. It is, of course, to be observed that relay 47 may be replaced by an electronic switch of a type well known in the art.
  • Apparatus for exercising control over a fluid driven system said fluid driven system including a variable capacity pump coupled to a motor by conduit means and actuator means connected to the pump for adjusting the capacity thereof, said control apparatus comprising:
  • control signal generating means responsive to electrical signals applied thereto for generating actuator means electrical control signals when one of said signals commensurate with pressure exceeds a predetermined value
  • the apparatus of claim 1 further comprising: means for generating a signal commensurate with pump capacity;
  • a pressure sensor operatively associated with each of said conduits, said sensors including piston means positioned in relation to conduit pressure; and transducer means mechanically connected to each of said sensor piston means for generating electrical signals commensurate with conduit pressure.
  • a pressure sensor operatively associated with each of said conduits, said sensors including piston means positioned in relation to conduit pressure;
  • transducer means mechanically connected to each of said sensor piston means for generating electrical signals commensurate with conduit pressure.
  • potentiometer means having its wiper arm mechanically coupled to said control signal generating means; and v means applying the signal generated by one of said transducer means across said potentiometer means.
  • Apparatus for exercising control over a fluid driven system said fluid driven system including a variable capacity pump coupled to a motor by conduit means and actuator means connected to the pump for adjusting the capacity thereof, said system further including an electric power prime mover for the pump, said control apparatus comprising:
  • the apparatus of claim 6 further comprising: voltage limiter means connected to said current sensing means for limiting the magnitude of the signals applied to the actuator controlling means.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
US00103476A 1970-01-09 1971-01-04 Control system Expired - Lifetime US3744243A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7000970A FR2037306A5 (US06235095-20010522-C00021.png) 1970-01-09 1970-01-09

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US3744243A true US3744243A (en) 1973-07-10

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US00103476A Expired - Lifetime US3744243A (en) 1970-01-09 1971-01-04 Control system

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US (1) US3744243A (US06235095-20010522-C00021.png)
DE (1) DE2057457A1 (US06235095-20010522-C00021.png)
FR (1) FR2037306A5 (US06235095-20010522-C00021.png)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4139987A (en) * 1977-01-04 1979-02-20 Tadeusz Budzich Load responsive system pump controls
US4355506A (en) * 1977-08-26 1982-10-26 Leonard Willie B Pump-motor power limiter and pressure relief
US4510750A (en) * 1980-06-04 1985-04-16 Hitachi Construction Machinery Co., Ltd. Circuit pressure control system for hydrostatic power transmission
US4528813A (en) * 1980-08-06 1985-07-16 Hitachi Construction Machinery Co., Ltd. Control system for hydrostatic power transmission
US4537364A (en) * 1982-12-15 1985-08-27 Sundstrand Corporation Constant tension cable reel drive
US5569156A (en) * 1993-09-10 1996-10-29 Ottawa Heart Institute Research Corporation Electrohydraulic ventricular assist device
US5865602A (en) * 1995-03-14 1999-02-02 The Boeing Company Aircraft hydraulic pump control system
US6623247B2 (en) * 2001-05-16 2003-09-23 Caterpillar Inc Method and apparatus for controlling a variable displacement hydraulic pump
US6848254B2 (en) 2003-06-30 2005-02-01 Caterpillar Inc. Method and apparatus for controlling a hydraulic motor
US20080294098A1 (en) * 2007-05-22 2008-11-27 Medtronic, Inc. End of stroke detection for electromagnetic pump
US20100154400A1 (en) * 2008-12-23 2010-06-24 Caterpillar, Inc. Hydraulic control system utilizing feed-foward control
US20100154401A1 (en) * 2008-12-23 2010-06-24 Caterpillar Inc. Hydraulic control system having flow force compensation
US20110000203A1 (en) * 2008-03-10 2011-01-06 Parker Hannifin Corporation Hydraulic system having multiple actuators and an associated control method
US9234532B2 (en) 2008-09-03 2016-01-12 Parker-Hannifin Corporation Velocity control of unbalanced hydraulic actuator subjected to over-center load conditions

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1204983A (en) * 1982-12-13 1986-05-27 Richard Beck, Jr. Anti-plug control

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE412816C (de) * 1925-04-28 Siemens Schuckertwerke G M B H Hydraulische Kupplung
US3186170A (en) * 1962-06-26 1965-06-01 Sigma Variable ratio hydraulic transmissions
US3537363A (en) * 1968-07-17 1970-11-03 Long George Servo-controlled hydraulic system
US3609971A (en) * 1968-02-27 1971-10-05 Ludwig Maurer & Co Fa Method and apparatus for controlling the drive of pressure-fluid actuated machine elements

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE412816C (de) * 1925-04-28 Siemens Schuckertwerke G M B H Hydraulische Kupplung
US3186170A (en) * 1962-06-26 1965-06-01 Sigma Variable ratio hydraulic transmissions
US3609971A (en) * 1968-02-27 1971-10-05 Ludwig Maurer & Co Fa Method and apparatus for controlling the drive of pressure-fluid actuated machine elements
US3537363A (en) * 1968-07-17 1970-11-03 Long George Servo-controlled hydraulic system

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4139987A (en) * 1977-01-04 1979-02-20 Tadeusz Budzich Load responsive system pump controls
US4355506A (en) * 1977-08-26 1982-10-26 Leonard Willie B Pump-motor power limiter and pressure relief
US4510750A (en) * 1980-06-04 1985-04-16 Hitachi Construction Machinery Co., Ltd. Circuit pressure control system for hydrostatic power transmission
US4528813A (en) * 1980-08-06 1985-07-16 Hitachi Construction Machinery Co., Ltd. Control system for hydrostatic power transmission
US4537364A (en) * 1982-12-15 1985-08-27 Sundstrand Corporation Constant tension cable reel drive
US5569156A (en) * 1993-09-10 1996-10-29 Ottawa Heart Institute Research Corporation Electrohydraulic ventricular assist device
US5704891A (en) * 1993-09-10 1998-01-06 Ottawa Heart Institute Research Corporation Electrohydraulic ventricular assist device
US5865602A (en) * 1995-03-14 1999-02-02 The Boeing Company Aircraft hydraulic pump control system
US6623247B2 (en) * 2001-05-16 2003-09-23 Caterpillar Inc Method and apparatus for controlling a variable displacement hydraulic pump
US6848254B2 (en) 2003-06-30 2005-02-01 Caterpillar Inc. Method and apparatus for controlling a hydraulic motor
US20080294098A1 (en) * 2007-05-22 2008-11-27 Medtronic, Inc. End of stroke detection for electromagnetic pump
US8007247B2 (en) * 2007-05-22 2011-08-30 Medtronic, Inc. End of stroke detection for electromagnetic pump
US8657587B2 (en) 2007-05-22 2014-02-25 Medtronic, Inc. End of stroke detection for electromagnetic pump
US20110000203A1 (en) * 2008-03-10 2011-01-06 Parker Hannifin Corporation Hydraulic system having multiple actuators and an associated control method
US8726646B2 (en) 2008-03-10 2014-05-20 Parker-Hannifin Corporation Hydraulic system having multiple actuators and an associated control method
US9234532B2 (en) 2008-09-03 2016-01-12 Parker-Hannifin Corporation Velocity control of unbalanced hydraulic actuator subjected to over-center load conditions
US20100154400A1 (en) * 2008-12-23 2010-06-24 Caterpillar, Inc. Hydraulic control system utilizing feed-foward control
US20100154401A1 (en) * 2008-12-23 2010-06-24 Caterpillar Inc. Hydraulic control system having flow force compensation
US8511080B2 (en) 2008-12-23 2013-08-20 Caterpillar Inc. Hydraulic control system having flow force compensation
US8522543B2 (en) 2008-12-23 2013-09-03 Caterpillar Inc. Hydraulic control system utilizing feed-forward control

Also Published As

Publication number Publication date
FR2037306A5 (US06235095-20010522-C00021.png) 1970-12-31
DE2057457A1 (de) 1971-07-15

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