US2877626A - Electric control system for fluid operated actuators - Google Patents

Electric control system for fluid operated actuators Download PDF

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Publication number
US2877626A
US2877626A US652444A US65244457A US2877626A US 2877626 A US2877626 A US 2877626A US 652444 A US652444 A US 652444A US 65244457 A US65244457 A US 65244457A US 2877626 A US2877626 A US 2877626A
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Prior art keywords
switch
electro
magnet
motor
circuit
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Expired - Lifetime
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US652444A
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English (en)
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Gratzmuller Jean Louis
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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/02—Details
    • H01H33/28—Power arrangements internal to the switch for operating the driving mechanism
    • H01H33/30—Power arrangements internal to the switch for operating the driving mechanism using fluid actuator
    • H01H33/34—Power arrangements internal to the switch for operating the driving mechanism using fluid actuator hydraulic

Definitions

  • limit switches in an electrical circuit or circuits controlling the actuating means of the section switch.
  • limit switches present the serious disadvantage of requiring very precise adjustment to ensure completion of the movement of the mechanical parts without prolonging the effort exerted on and by them after completion of the movement. Should a limit switch be incorrectly adjusted or fail to operate, serious damage to the installation may be caused.
  • This invention is therefore more particularly concerned with a control system for controlling the hydraulic actuator or actuators of a section switch, said actuator or actuators being fed by a pump.
  • the control system therefore comprises an electric motor which drives the pump and means responsive to the pump delivery pressure for isolating the motor from its source of excitation when such pressure attains a predetermined critical value.
  • the section switch will normally be actuated by two single-acting hydraulic jacks, respectively effecting the closing and opening movements of the contact mechanism, or by one double-acting jack, which for presice . 2 ent purposes may be regarded -as a pair of oppositely acting single-acting jacks.
  • the pressure-responsive means comprise an electro-magnet' controlling the switch-gear of the pump motor, a switch controlling the excitation of the electro-magnet and a movable element controlling the switch, said element being subjected to the opposed efforts of the pump delivery pressure and of a calibrated spring.
  • a section switch control system employing electrical circuits and electro-magnetic devices ought to vsatisfy the following conditions:
  • a current failure of the electrical supply of any of the electro-magnetic devices during a movement of the contact mechanism of the section switch should restore the whole electrical system to its original state before such movement was initiated, so that no unintentional resumption of movement can occur when the current is re-established.
  • a further object of the invention is to provide an elec-v trical and electro-magnetic system for actuating the valve.
  • a preferred form of my improved contnol system there fore comprises, in addition to the features previously described, the following further features:
  • valve means controlling the Iactuator or actumeans are excitable through a holding circuit which includes an isolating switch mechanically coupled to the pump motor switch-gear so as to open when the motor' is isolated, and the exciting circuit of the electro-magnet controlling the motor switch-gear includes a switch or; switches sol actuated by the valve-,operating ⁇ electrol.
  • valve-operating electro-magnetic means is/ are initially excitable through a starting circuit or circuits in parallel with the holding circuit and including a controllable starting switch or switches which is/are normally open.
  • Each starting switch is a double-pole switch adapted to isolate its associated electro-magnet on both sides when opened.
  • Each valve-operating electro-magnet when excited closes la holding switch in its holding circuit, such holding switch and the isolating switch mechanically coupled to the motor switch-gear being disposed on opposite sides of the electro-magnet so as to isolate the iatter on both sides when both such switches are open.
  • condition (a) is satisedby features (ii), (iii) 'and (v) in combination
  • condition (b) is satisiied by features (iv) and (v) in combination
  • condition (c) is satised by feature (i).
  • the pump motor is preferably of the three-phase A. C. variety, the exciting circuit of the electro-magnet controlling the motor switch-gear being connected across two of the three-phases of the motor supply.
  • the movable contact mechanism of a section switch is actuated by two hydraulic actuators, such as single-acting jacks (not illustrated), one of which effects the closing movement and the other the opening movement of the contact mechanism.
  • actuators are respectively controlled by valves denoted 1 and 2 each of which can selectively connect a combined feed and exhaust pipe a or b counected to the actuator it controls, either to the delivery pipe c of a pump 3 -or to an exhaust pipe d.
  • Each valve is provided with a ball member which cooperates with a seat in the valve body to constitute an inlet valve means and a fluid pressure responsive valve component which cooperates with outlet ports to define an outlet valve.
  • the arrangement is such that the outlet valve, when moved by its plunger in one direction, opens the inlet valve while maintaining the outlet ports closed, whereas fluid pressure from the conduit a moves the outlet valve in. the other direction to establish a communication between the conduit a and the exhaust pipe d through the outlet ports while the inlet valve remains closed.
  • Pump 3 is driven by a threephase A. C. electric motor 4 supplied from a three-phase current source 5, 6, 7 and is controlled by a switch-gear here represented for the sake of simplicity by a three-blade switch 28, 29, 30 ⁇ actuated by the armature 31 of an electro-magnet 32 so as to close when the, electro-magnet is excited, the switch 28, 29, 30. being biased to the Open position by a spring 34.
  • the motor switch-gear will preferably be of the kind which is standard equipment for three-phase motors.
  • The'el'ectro-magnet 32 is excitable through la circuit 411, 421,43-, 44 containing a switch 39 actuated through a rod 3@ by4 a piston 37l sliding in a cylinder 36 and subjected to the Opposed eiorts of a calibrated spring 40 and the delivery pressure of pump 3 applied through a pipe 35.
  • the pump delivery pressure exceeds a predetermined critical value to which spring 40 is calibrated, lthe latter yields and allows piston 37 to open switch 39 and isolate the electro-magnet 32, thus causing the motor switch 28, 29, 30 to open and isolate the motor 4, thus stopping the pump 3 and preventing further build-up ot pressure in the pump delivery pipe c.
  • the excitation of the electro-magnet 32 is derived from two of the phases 6, "I, of the three-phase supply for the motor 4, so that a temporary failure of this supply will not only stop the motor but by stopping the excitation of electro-magnet 32 will cause the motor to be isolated.
  • the electromagnet 32 will not be re-ex-cited to start the motor again because, as hereinafter explained, the opening of the motor switch 28, 29, 30 causes the exciting circuit of the electro-magnet 32 to be interrupted at another point, and it can only be re-established by a purposive action of the operator.
  • the control valves 1, 2 are operated by electro-magnetic means excitable from an independent D. C. supply 49, S4. Each valve 1, 2 has an operating plunger 8 or 14 carried by an extension of the armature 9 or 15 of an electro-magnet 10 or 16. Excitation of either of theseelectro-magnets causes its armature 9 or 15 and plunger 8 or 14 to be depressed and set the valve 1 or 2 to connect the pump delivery pipe c to the feed pipe a or b of the corresponding hydraulic actuator and energize the same to move the Contact mechanism of the section switch, in the closing or opening sense according to which of the electro-magnets 10, 16 is excited.
  • Electro-magnet 10 is initially excitable through a starting circuit 49, S0, 51, 52, 53, 54 closable by a doublepol'e starting switch 24, 25 which is normally kept open by a spring 22 and can be closed by a push-button 20.
  • switch 2li, 25 isolates electro-magnet 10 on both sides since the contact 24 is in the positive branch 49, 50, 51 of the starting circuit, the contact 25 being in its negative branch 52, 53, 54.
  • electro-magnet 16 is initially excitable through a starting circuit 49,. 55, 56, 50, 57, 58, 59, 69, 54 containing a double-pole starting switch 26, 27 normally held open by a spring 23 to interrupt both the positive and negative branches of the starting circuit and closable by a push-button 21.
  • each electro-magnet 10, 16 further carries the movable Contact members of three switches, viz 11, 12, 13 and 17, 18, 19 respectively.
  • Switch 12 is an isolating switch in the negative branch 58, 59 of the starting circuit of electro-magnet 16 and is closed except when electro-magnet 1t) is excited.
  • switch 18 is an isolating switch in the negative branch 52, 53 o the starting circuit of electro-magnet 1t) and is closed except when electromagnet 16 is excited.
  • excitation of either electro-magnet 10 or 16 opens the starting circuit of the other and renders its starting switch inoperative to excite it.
  • Switches 11, 17 are holding switches for their respective electro-magnets.
  • electro-magnet 10 when electro-magnet 10 is rst excited it closes Switch 11, previously open, and establishes its holding circuit through conductors 62, 63, Sil, S1, 52, 64, 65, 61.
  • initial excitation of electro-magnet 16 closes its holding circuit 62, 63, 57, 58, 66, 61 when switch 17 is closed.
  • Switch 33 is mechanically coupled' to the motor switch 28, 29, 3l) and is ⁇ opened when the latter opens. Therefore, when the pump delivery pressure rises above the critical f-Lilue on completion of the stroke of either actuator and opens the switch 39, not only is the motor switch opened as previously explained but switch 33 is likewise opened, thereby opening the holding circuit and terminating the excitation or" the electro-magnet lil or 16 concerned,
  • the type of switch-gear which is standard equipment for a three-phase motor usually includes, in addition to various protective relays, a holding switch, which closes when the main motor switch closes to maintain the main switch in closed lposition.
  • this holding switch may he utilized as the switch 33 labove mentioned, by disconnecting it from its normal circuit and connecting it to the conductors 62, 63 as illustrated.
  • the switch-gear includes a spare switch which opens and closes with the main motor switch and has terminals for connecting an external circuit, e. g. a signalling circuit, such spare switch may be used as the switch 33, its terminals being connected to conductors 62, 63.
  • Switches 13 and 19 are connected in parallel branches 47, 48 and 45, 46 respectively of the exciting circuit 41-44 of electro-magnet 32. They are open when electro-magnets lil and 16 are not excited, but when one of these electro-magnets is excited, say 10, the associated switch 13 closes and completes the exciting circuit 41-44 of electro-magnet 32.
  • An electric control system for a pressure lluid operated actuator comprising, in co-mbination, a pump, an electric motor for operating the pump, a switch-gear for controlling the circuit to said motor, an electro-magnet connected to said circuit for operating said switch-gear, pressure operated means to break the circuit of said electro-magnet when the delivery pressure of said pump reaches a predetermined value to thereby allow said switch-gear to break the circuit to said motor, a valve device for controlling the ilow of liquid from said pump to said actuator or from the latter to the exhaust, electromagnetic means for operating said valve device and including a holding circuit, an isolating switch in said holding circuit movable with said switch-gear so as to interrupt said holding circuit when said switch-gear is moved into open position, and switch means in the circuit of said electro-magnet so actuated by said electro-magnetic means as to close only when said electro-magnetic means are energized.
  • valve-operating electro-magnetic means is initially ⁇ excitable through a starting circuit in parallel with the holding circuit, said starting circuit including a controllable starting switch which is normally open.
  • a control system as claimed in claim 2 for controlling two lluid operated actuators comprising a valve device controlling each actuator and an electro-magnetic means operating each valve device, a separate starting circuit for each electro-magnetic means, each starting circuit including a starting switch and also an isolating switch so actuated by the electro-magnetic means controlled by the other starting circuit as to ⁇ be opened when said last mentioned electro-magnetic means is excited.
  • each starting switch is a double pole switch adapted when opened to isolate the electro-magnet controlled thereby on both sides.
  • each electromagnetic means when excited closes a holding switch in its holding circuit, the isolating switch movable with said switch-gear and said holding switch being disposed on opposite sides of the electro-magnetic means, so as to isolate the latter on both sides when both such switches are open.
  • a control system as claimed in claim l in whichsaid electric motor is of the three-phase alternating current type, the circuit of said electro-magnet being connected across two of the three conductors of the threephase source from which the motor is excited.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)
US652444A 1956-04-18 1957-04-12 Electric control system for fluid operated actuators Expired - Lifetime US2877626A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR1244276X 1956-04-18

Publications (1)

Publication Number Publication Date
US2877626A true US2877626A (en) 1959-03-17

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Family Applications (1)

Application Number Title Priority Date Filing Date
US652444A Expired - Lifetime US2877626A (en) 1956-04-18 1957-04-12 Electric control system for fluid operated actuators

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US (1) US2877626A (enrdf_load_stackoverflow)
BE (1) BE556800A (enrdf_load_stackoverflow)
CH (1) CH342625A (enrdf_load_stackoverflow)
DE (1) DE1244276B (enrdf_load_stackoverflow)
FR (1) FR1149930A (enrdf_load_stackoverflow)
GB (1) GB831888A (enrdf_load_stackoverflow)
NL (2) NL272080A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3630025A (en) * 1970-06-01 1971-12-28 Allis Chalmers Mfg Co Control system for hydraulic devices

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3932930A1 (de) * 1989-10-03 1991-04-11 Pistor & Boss Gmbh Gegen mikrowellen abgeschirmte elektrische leuchte

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1711565A (en) * 1926-04-12 1929-05-07 Hatfield Crabbe Company Automobile jack
US2457467A (en) * 1945-03-08 1948-12-28 Cons Vultee Aircraft Corp Electrically and hydraulically operated extensible strut

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE301145C (enrdf_load_stackoverflow) *
US2736009A (en) * 1956-02-21 Lilzlj
DE522738C (de) * 1929-06-21 1931-04-14 Explosionssicherer Gefaesse Sa Brennstoffzapf- und Messeinrichtung mit motorisch betriebener Foerderpumpe
FR1073119A (fr) * 1953-03-20 1954-09-20 Merlin Gerin Dispositif de compensation de fuites

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1711565A (en) * 1926-04-12 1929-05-07 Hatfield Crabbe Company Automobile jack
US2457467A (en) * 1945-03-08 1948-12-28 Cons Vultee Aircraft Corp Electrically and hydraulically operated extensible strut

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3630025A (en) * 1970-06-01 1971-12-28 Allis Chalmers Mfg Co Control system for hydraulic devices

Also Published As

Publication number Publication date
CH342625A (fr) 1959-11-30
FR1149930A (fr) 1958-01-03
NL272080A (enrdf_load_stackoverflow)
GB831888A (en) 1960-04-06
BE556800A (enrdf_load_stackoverflow)
DE1244276B (de) 1967-07-13
NL216441A (enrdf_load_stackoverflow)

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