EP0718496A2 - Système électrohydraulique à assistance variable - Google Patents

Système électrohydraulique à assistance variable Download PDF

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Publication number
EP0718496A2
EP0718496A2 EP95308558A EP95308558A EP0718496A2 EP 0718496 A2 EP0718496 A2 EP 0718496A2 EP 95308558 A EP95308558 A EP 95308558A EP 95308558 A EP95308558 A EP 95308558A EP 0718496 A2 EP0718496 A2 EP 0718496A2
Authority
EP
European Patent Office
Prior art keywords
electro
motor
hydraulic system
current
pump
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Withdrawn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
EP95308558A
Other languages
German (de)
English (en)
Other versions
EP0718496A3 (fr
Inventor
Matthew B. Dernier
Ulisses Duarte Camilo
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.)
Lockheed Martin Corp
Original Assignee
Martin Marietta Corp
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 Martin Marietta Corp filed Critical Martin Marietta Corp
Publication of EP0718496A2 publication Critical patent/EP0718496A2/fr
Publication of EP0718496A3 publication Critical patent/EP0718496A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/02—Motor parameters of rotating electric motors
    • F04B2203/0201—Current
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/02—Motor parameters of rotating electric motors
    • F04B2203/0202—Voltage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2207/00—External parameters
    • F04B2207/01—Load in general

Definitions

  • the present invention relates to electro-hydraulic systems and, more particularly, to a novel electro-hydraulic system in which pump pressure is determined by a variable motor speed responsive to hydraulic load effects upon a motor parameter internally sensed in the motor controller.
  • hydraulic fluid is provided under pressure by a pump driven by an electric motor; the motor is often run at a fixed RPM rate.
  • the motor is often run at a fixed RPM rate.
  • some energy will be drawn from an electrical supply; that energy will not be used to provide any useful function.
  • electrical components will experience undue voltage and current levels and mechanical components will be required to operate at higher stress levels resulting in elevated temperatures and, ultimately, lower reliability.
  • an electro-hydraulic system has at least one hydraulic load receiving pressurized fluid from a pump energized by an electric motor; the fluid flow/pressure characteristics are determined by motor speed, which is set by an electronic controller responsive to a motor/pump parameter sensed within the controller itself. No system parameter external to the electronic controller is required to be sensed to maintain system operation.
  • the sensed parameter is motor current, which increases if pump load has increased.
  • the sole Figure is a schematic block diagram of a presently preferred embodiment of our novel variable-assist electro-hydraulic system.
  • a variable-assist electro-hydraulic system 10 has at least one hydraulic load 11, such as the plurality of loads 11a, 11b, ..., 11n, each connected to a source 12 (such as a pump driven by a shaft 12a) of pressurized hydraulic media, flowing in conduit means 14 interconnecting the pump source 12 and the various loads 11.
  • a source 12 such as a pump driven by a shaft 12a
  • each sensor would provide a separate signal for feedback to a control means 16, which provides at least one electric power signal (e.g. the three-phase power signals ⁇ a , ⁇ b and ⁇ c , respectively at control means outputs 16a-1, 16a-2 and 16a-3)to a motor means 18 serving to rotate pump shaft 12a at a rotational speed determined in response to the feedback sensor signals.
  • a control means 16 which provides at least one electric power signal (e.g. the three-phase power signals ⁇ a , ⁇ b and ⁇ c , respectively at control means outputs 16a-1, 16a-2 and 16a-3)to a motor means 18 serving to rotate pump shaft 12a at a rotational speed determined in response to the feedback sensor signals.
  • Control means 16 includes a power switching means 20, such as a full-bridge switch means and the like, providing the respective first, second and third phase signals at its respective 20a, 20b and 20c outputs, responsive to a characteristic of a control signal applied at a control input 20d; an operating potential V++ is applied to input 20e (from means input 16b-1), with respect to a return RTN potential at input 20f terminal 20f (from means input 16b-2).
  • a power switching means 20 such as a full-bridge switch means and the like, providing the respective first, second and third phase signals at its respective 20a, 20b and 20c outputs, responsive to a characteristic of a control signal applied at a control input 20d; an operating potential V++ is applied to input 20e (from means input 16b-1), with respect to a return RTN potential at input 20f terminal 20f (from means input 16b-2).
  • the control signal at input 20d is provided at the control output 22a of a loop control means 22, responsive to the magnitude of a variable reference VAR REF signal at a first input 22b and a sensed current signal provided at a second input 22c by a current sensing means 24; another operating potential V+ is applied to an input 22de (from means input 16b-3), with respect to a return RTN potential at input terminal 22e (from means input 16b-4).
  • each of the three different phase currents ⁇ a , ⁇ b and ⁇ c is sampled by an associated one of current sensor (transformer) means 26a/26b/26c and the sensor means pairs of leads provide an associated signal at each associated input 24a/24b/24c, to generate the single system-current signal at output 24d, in manner well-known to the art.
  • current sensor transformer
  • signals internal to means 16 are used to obtain the hydraulic-load-responsive motor current signal to be provided at loop control input 22c, without need for any sensor external to means 16.
  • the other loop control means signal (the VAR REF signal at input 22b) is also generated internal to means 16.
  • the controller 16 includes a variable reference generator means 28 receiving at an input 28a only one selected one of the motor current sensing means 26 outputs (e.g. the output of the phase ⁇ a current sensor 26a) for connection to the input 30a of a current-to-voltage conversion means 30.
  • the resulting motor-current-analog voltage V m related to the hydraulic load magnitude, and appearing at the conversion means output 30b, is connected to the input 32a of a rectification means 32.
  • the rectified voltage V r at means output 32b is coupled to one input 34a of a comparison means 34, receiving a selectable trip signal V trip at another input 34b.
  • the comparator output 34c signal V c will be at a first level (e.g. a high level) if V r ⁇ V trip , and will be at another level (e.g. a low level) if V r > V trip . If the first V C level is present, as when the pump is providing adequate fluid pressure and flow, then the motor can be controlled to/kept in a low/idle state; if the second V C level is output, indicative of the motor having to work harder to turn the pump to provide higher fluid pressure and flow, then the motor should be controlled to a more active/faster state.
  • the comparator output signal is applied to the input 36a of a driver means 36, to generate the VAR REF signal at output 36b/28b, for application to input 22b.
  • the current-to-voltage converter means 30 has a transformer means 38, with a primary winding 38a of relative few turns N p , connected between the two input conductors 30a-1 and 30a-2, from the selected motor phase current sensor 26a.
  • the transformer secondary winding 38b having relatively many turns N s > > N P (say, 200:1), has a first end coupled to circuit common (RTN) potential through a first resistance element 40, and another end connected to a first, inverting (-) input 42a of a first operational amplifier 42.
  • the other, non-inverting (+) op-amp input 42b is coupled to common potential through a second resistance element 44.
  • a conversion-factor-setting feedback resistance element 46 is connected between input 42a and op-amp output 42c, which is connected to means output 30b, at which the signal V m is generated responsive to the ⁇ a motor current. Signal V m is then applied to means 32 input 32a.
  • Rectification means 32 includes a first resistance element 48 coupled from input 32a to a first, inverting (-) input 50a of another operational amplifier 50.
  • the other, non-inverting (+) op-amp input 50b is coupled to common potential through a second resistance element 52.
  • a gain-setting feedback resistance element 54 is connected between input 50a and op-amp output 50c, which is connected to the anode of a rectifier diode 56, having its cathode connected to means output 32b, to which are also connected one terminal of each of a load resistance element 58 and filter capacitance element 60, having their other terminals connected to common potential; the signal V r is generated at output 32b responsive to the peak of the ⁇ a motor current.
  • Signal V r is then applied through means 34 input 34a to a first, inverting (-) input 62a of a comparator 62.
  • a trip voltage V trip from input 34b is applied to the other, non-inverting (+) input 62b of the comparator.
  • a resistance element 66 is connected between the operating potential V+ source and the comparator output 62c, which output is also the means output 34c.
  • the driver means input 36a is coupled through a resistance element 68 to a control (base) device electrode of a switching device (transistor) 70; a common (source) device electrode is connected to common potential and a controlled (collector) device electrode is coupled to output 36b/28b through another resistance element 72; a pair of series-connected resistance elements 74 is connected from operating potential V+ to the output, which is coupled through yet another resistance element 76 to common potential.
  • a ramping/smoothing capacitor 78 is connected in parallel with resistor 76.
  • a maximum-voltage (V max )-establishing zener diode 80 is connected at the junction between resistors 74a and 74b.
  • system 10 eliminates the need for multiple separate sensors and interfaces by extracting inherent information from the electronic control signals which are always present in the system. Since the pressure in the hydraulic lines 14 is a function of the total loading presented by the hydraulic means 11a-11n, hydraulic pressure is an inherent indication of the load. Generally, when the load increases, there is a corresponding requirement for additional hydraulic flow with a resultant increase in pressure. The converse is true for a decrease in load.
  • the variations in hydraulic pressure relate back to quantities in the electronic control means 16 through the hydraulic pump 12 and electric motor 18, as follows: an increase in hydraulic pressure will create an increase in torque at pump input shaft 12a; the increased load torque applied to electric motor 18 by pump 12 will result in an increased current draw by motor 18.
  • an inherent indication of load demand is present within the electronic control means 16, by monitoring one or more phase currents by means of a current sensor 26.
  • This inherent, or “load proportional” (control drive derived from load demand), load indicator can be used to control the system so as to reduce fixed power losses and increase system reliability.
  • the hydraulic flow rate is directly proportional to motor speed and by commanding the motor to run at high speeds only when the load demands it, all of the advantages described above can be achieved.
  • the electronic control will command the motor to run at a speed proportional to the variable "VAR REF' voltage.
  • the control circuitry 28 will change the "VAR REF" voltage level and motor 18 will then be commanded to servo from one speed to another.
  • VAR REF voltage will then increase to a maximum set by the zener voltage of diode 80 and the ratio of resistors 76 and 74b. Motor 18 will then servo up to a higher speed (with timing dependent upon capacitor 78), to provide increased hydraulic flow and pressure. Resistors 74b and 76 (and capacitor 78) are selected to limit motor acceleration, in order to minimize excessive motor current.
  • the standby current draw (when no power steering boost is required) was typically 3A DC.
  • the load-proportional control of our novel system the standby current draw was reduced to only 0.3A DC. Assuming an 80% system efficiency, the load proportional system dissipated only 10 watts as opposed to 100 watts in the conventional system; the resultant temperature decrease in some electrical and mechanical components can be significant.
  • the filter set up by resistors 74 and capacitor 78, allows proper state changes of comparator output V c without hysteresis. In the no-load condition, VAR REF tends to stabilize at 2.0 VDC, to implement a motor speed of about 800 RPM.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
EP95308558A 1994-12-19 1995-11-28 Système électrohydraulique à assistance variable Withdrawn EP0718496A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US35850694A 1994-12-19 1994-12-19
US358506 1994-12-19

Publications (2)

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EP0718496A2 true EP0718496A2 (fr) 1996-06-26
EP0718496A3 EP0718496A3 (fr) 1998-12-02

Family

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EP95308558A Withdrawn EP0718496A3 (fr) 1994-12-19 1995-11-28 Système électrohydraulique à assistance variable

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998002282A1 (fr) * 1996-07-17 1998-01-22 Applied Power Inc. Unite de pompage a transducteur de vitesse
DE19842565A1 (de) * 1998-09-03 2000-03-09 Ksb Ag Automatische Ermittlung der PID-Reglerparameter für einen Druckregelkreis in Mehrpumpenanlagen
US6863502B2 (en) 2000-04-14 2005-03-08 Actuant Corporation Variable speed hydraulic pump
US6935639B1 (en) * 2004-02-18 2005-08-30 Visteon Global Technologies, Inc. Mean pressure estimation for compressible fluid strut
EP1598555A1 (fr) * 2004-05-21 2005-11-23 Koyo-Hpi Système de groupe électro-pompe pourvu de moyens de limitation de la pression du fluide hydraulique fourni par la pompe
US10125841B2 (en) 2010-07-05 2018-11-13 Fluid Ride, Ltd. Suspension strut for a vehicle
EP3501734A1 (fr) * 2008-03-26 2019-06-26 Quantum Servo Pumping Technologies Pty Ltd Pompe ultra-haute pression à mécanisme d'entraînement à déplacement de rotation/linéaire alternatif
EP3789612A1 (fr) 2019-09-06 2021-03-10 Weber-Hydraulik GmbH Appareil hydraulique portable fonctionnant sur accumulateur pour outils de sauvetage hydraulique

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9574582B2 (en) 2012-04-23 2017-02-21 Fluid Ride, Ltd. Hydraulic pump system and method of operation

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4145161A (en) * 1977-08-10 1979-03-20 Standard Oil Company (Indiana) Speed control
DE3210082A1 (de) * 1981-04-02 1982-10-21 IWE Ingenieurgesellschaft für wirtschaftliche Energienutzung mbH, 6078 Neu-Isenburg Verfahren und schaltungsanordnung zur regelung der drehzahl eines pumpenmotors
JPH0742056B2 (ja) * 1989-06-15 1995-05-10 三菱電機株式会社 流体圧エレベータ制御装置
US5126642A (en) * 1991-01-31 1992-06-30 Ranco Incorporated Of Delaware Variable speed motor control
DE4301581A1 (de) * 1993-01-21 1994-07-28 Still Gmbh Hydraulische Lenkregelung bei einem Elektrofahrzeug
US5467281A (en) * 1993-03-13 1995-11-14 Toyoda Koki Kabushiki Kaisha Controller for power steering apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998002282A1 (fr) * 1996-07-17 1998-01-22 Applied Power Inc. Unite de pompage a transducteur de vitesse
US5792967A (en) * 1996-07-17 1998-08-11 Applied Power Inc. Pumping unit with speed transducer
DE19842565A1 (de) * 1998-09-03 2000-03-09 Ksb Ag Automatische Ermittlung der PID-Reglerparameter für einen Druckregelkreis in Mehrpumpenanlagen
DE19842565B4 (de) * 1998-09-03 2005-08-25 Ksb Ag Automatische Ermittlung der PID-Reglerparameter für einen Druckregelkreis in Mehrpumpenanlagen
US6863502B2 (en) 2000-04-14 2005-03-08 Actuant Corporation Variable speed hydraulic pump
US6935639B1 (en) * 2004-02-18 2005-08-30 Visteon Global Technologies, Inc. Mean pressure estimation for compressible fluid strut
EP1598555A1 (fr) * 2004-05-21 2005-11-23 Koyo-Hpi Système de groupe électro-pompe pourvu de moyens de limitation de la pression du fluide hydraulique fourni par la pompe
FR2870570A1 (fr) * 2004-05-21 2005-11-25 Koyo Hpi Soc Par Actions Simpl Systeme de groupe electro-pompe pourvu de moyens de limitation de la pression du fluide hydraulique fourni par la pompe
EP3501734A1 (fr) * 2008-03-26 2019-06-26 Quantum Servo Pumping Technologies Pty Ltd Pompe ultra-haute pression à mécanisme d'entraînement à déplacement de rotation/linéaire alternatif
US10125841B2 (en) 2010-07-05 2018-11-13 Fluid Ride, Ltd. Suspension strut for a vehicle
EP3789612A1 (fr) 2019-09-06 2021-03-10 Weber-Hydraulik GmbH Appareil hydraulique portable fonctionnant sur accumulateur pour outils de sauvetage hydraulique

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Publication number Publication date
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