US3878764A - Double-hydraulic actuator - Google Patents

Double-hydraulic actuator Download PDF

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Publication number
US3878764A
US3878764A US227889A US22788972A US3878764A US 3878764 A US3878764 A US 3878764A US 227889 A US227889 A US 227889A US 22788972 A US22788972 A US 22788972A US 3878764 A US3878764 A US 3878764A
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United States
Prior art keywords
servomotors
piston rods
control member
common control
movement
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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.)
Expired - Lifetime
Application number
US227889A
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English (en)
Inventor
Hans Zech
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.)
Airbus Defence and Space GmbH
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Messerschmitt Bolkow Blohm AG
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Filing date
Publication date
Priority claimed from DE19712108545 external-priority patent/DE2108545C/de
Application filed by Messerschmitt Bolkow Blohm AG filed Critical Messerschmitt Bolkow Blohm AG
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Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F15B18/00—Parallel arrangements of independent servomotor systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C13/00—Control systems or transmitting systems for actuating flying-control surfaces, lift-increasing flaps, air brakes, or spoilers
    • B64C13/24—Transmitting means

Definitions

  • ABSTRACT Control for a tandem connected, redundant servo motor system.
  • the tandem connected servo motors are each provided with a suitable control valve and independent pressure fluid supplies therethrough.
  • a single control linkage is provided for both control valves and said linkage is connected to each valve by mechanically over-rideable means so that if one valve sticks the other can still be operated.
  • Means are provided normally holding energizing pressure on a selected first motor and off the second motor, said means being responsive to an over-riding of said overrideable means to reverse the pressure conditions on the motors.
  • DOUBLE-HYDRAULIC ACTUATOR Hydraulic actuators particularly those for controls of air and spacecraft, must be constructed redundantly for reasons of safety, that is, at least in duplicate, so that in case one (asthe main) drive breaks down at least one second (auxiliary) drive is able to automatically take over the function of the first one.
  • this objective cannot be fulfilled merely by mechanically coupling two so-called simple hydraulic actuators with the same output and by permitting same to operate a common output member.
  • a further problem is that an actuator as above referred to requires, furthermore, an extremely exact adjustment of its coupled control valves which in turn requires a correspondingly great expenditure of effort during manufacture thereof.
  • control valves of simple servo motors are to be coupled, and thus are designed substantially for use in so-called simple servohydraulics, then it is not possible to make symmetric the hydraulic functions of these control valves over their entire control range. Due to the different valve curves (stroke/flow) one must count both on a considerable reduction of the regulating speeds and also on entirely asymmetric pressure relations in the operating cylinder chambers. It has been proven that for this reason operating piston forces can occur which are partly opposed and thus causes the effective actuating force of the drive to be at least materially reduced.
  • the purpose of the invention is to produce a doublehydraulic actuator which remains operative when one of its mechanically coupled control valves or control valve pistons becomes inoperative or when an energy supply breaks down.
  • a further purpose is to produce an actuator which no longer requires the hydraulic functions of the control valves to be symmetrical and which will not become inoperative. Upon the occurrence of a blocking, or seizing as has already been mentioned, for example, a sticking of a control valve piston.
  • the aforementioned switching element is in active engagement with at least one of the positive connections, advantageously with the one of the control valve piston rod of the servo motor which serves as main drive.
  • a differential cylinder can be provided as switching element, which cylinder on the piston side is loaded by the supply pressure of the first servo motor and on the piston rod side (annular chamber) by the supply pressure of the second servo motor, whereby its piston rod actively engages a shut-off device for the pressure source which supplies the second servo motor.
  • this arrangement has the advantage that the differential cylinder also in case of a breakdown of a hydraulic energy circuit, preferably the main servo motor, automatically switches to a hydraulically active condition the second (auxiliary) servo motor which has been moving along on stand-by.
  • the servo motors are also in case of operation breakdown or damage easily and individually replaceable. At the same time this tends to solve the problem of quickly installing double-hydraulic actuators where needed and to adjust same to the respective requirements (actuating forces and the like). This problem exists particularly in carrying out projects of the air and space flight especially, during the testing phase.
  • FIG. 1 is a schematic view of a control in which only one mechanical linkage is provided for transmitting of control signals to a double-hydraulic actuator.
  • FIG. 2 is a perspective view of details of the connection between a control valve piston rod and a structural part of the linkage according to FIG. 1 and FIG. 2a is a partial view of a detail according to FIG. 2.
  • a control surface 1, for example an elevator of an aircraft, can be pivoted by two mechanically coupled servo motors 2 and 3 which are provided therefore with operating cylinders having piston rods 4 and 5 extending therethrough.
  • the latter are axially fixedly connected by a coupling 6 of the usual type of construction, for example a connecting rod coupling; and they are radially movable, within limits, in order to compensate for angle errors and the like.
  • the servo motors 2 and 3 are simple servo motors with an equal output and they actuate a commmon output member such as a linkage 7 which is connected to the control surface 1 and to new power piston rod 4 of the servo motor 2 which is used as a main drive.
  • the servo motors 2 or 3 which are connected to a separate pressure source 8 or 9 only one is constantly hydraulically active while the second one follows in readiness but without pressure thereon. This will be discussed more in detail below.
  • the control valves 10 and 11 of the servo motors 2 or 3 are coupled by a linkage in which, as in a parallelcrank mechanism, two two-arm levers 12 or 13 are pivotally connected at one respective end of each thereof by a piston rod 14 and at the other respective ends of each thereof the levers 12 or 13 are each hinged to one of the power piston rods 4 or 5.
  • the piston rod 14 can for example be moved by a control stick which acts on its left end 50.
  • the control valves are of the type having so-called by-pass mechanism (by-pass valve) which operates in response to pressure and act during reduction or failure of supply pressure to close an otherwise free passage for the pressure medium which passage normally is provided between the chambers of the associated operating cylinder.
  • Each lever 12 and 13 is provided with a cap screw 15 which is arranged freely movably in a not illustrated axially elongated slot in the associated control valve piston rod 16 or 17 (coupling part 18).
  • the coupling parts 18 are guided through the associated lever 12 or 13 which has therefore an opening 19 in the zone of its axis of rotation.
  • the piston rod 14 it can, in view of an easier adjustment of the coupled levers 12 and 13, be additionally equipped with the usual screw locks or the like.
  • the connections for transmitting control forces between the levers l2, l3 and the associated control valve piston rods 16 or 17 are provided at the outer ends of the coupling parts 18.- Details of these connections, which are the same in both control valve piston rods 16 and 17, are illustrated in FIG. 2 but only in connection with the control valve piston rod 16 of the main servo motor 2. According to such figure the aforementioned cap screw 15 is used as a pivotal connector for two lever elements 20 which extend on both sides of the coupling part 18. The lever elements 20 are at their outer ends 21 hinged pivotably, and at the same time axially movably, to a further pivot means 22 which is fixedly arranged in the coupling part 18. Each lever element 20 has an elongated slot 54 (FIG.
  • each spring 23 holds the pivot 22 in the elongated slot of the associated lever element 20 in a central position through movable sliding members 24.
  • the outer ends 21 of the lever elements 20 are for this purpose constructed as bearing housings for these connecting elements (spring elements 23, sliding members 24).
  • the coupled levers l2 and 13 can be pivoted relative to the associated power piston rod 4 or 5 even if one of the control valve pistons (not illustrated) is blocked.
  • the spring elements 23 which oppose the respective control forces in such case permits an axial shifting of whichever of the lever elements 20 is associated with the blocked piston and do so in each control direction. It is understood that this shifting is possible only if the normal control forces are exceeded and that only the spring elements which belong to these lever elements become effective.
  • a blocked control valve piston thus does not result in blocking the linkage, instead, it is only necessary to produce greater control forces to overcome and override the spring connectors. If the control valve piston of the main servo motor 2 is blocked, then an automatic switch to the second (auxiliary) servo motor 3 or its control valve 11 takes place whereby this motor is switched hydraulically active and the faulty one is depressurized.
  • a differential cylinder 25 is provided which is loaded on its piston side 26 through a pressure line 51 by the supply pressure 8 of the main servo motor 2 and on its piston rod side 27 (annular chamber 28) through a pressure line 52 by the supply pressure 9 of the auxiliary servo motor 3.
  • shut-off device 31 which is connected into a supply line 53 which connects the auxiliary servo motor 3 to its pressure source 9. It can be seen (FIG. 1) that this shut-off device 31 does not influence the loading of the annular chamber 28 by the supply pressure of the last-mentioned motor. Furthermore, a shut-off device 32 is connected into the pressure line 51 between the piston side 26 of the differential cylinder 25 and the pressure source 8 which supplies the main servo motor 2, which shut-off device is operable in response to the spring elements 23 of the connection of control valve piston rod 16 and lever 12. This is indicated by the dash-dotted line 33.
  • the shutoff valve 32 can for example be a magnetic valve the circuit of which is closed or opened by a contact which is operated by the aforementioned spring elements 23.
  • a shut-off device 35 is connected into a supply line 34 which connects the control valve 10 of the main servo motor 2 to its pressure source 8. Said shut-off valve is coupled through a linkage 36 to the first shutoff device 31.
  • shut-off devices 31 and 35 Only one of the two mechanically coupled shut-off devices 31 and 35, for example spool valves, is open while the other one blocks or vice versa. If for example the third shut-off device 35 is open and thus the main servo motor 2 is energized, the pressure medium supply to the auxiliary servo motor 3 or its control valve 11 is blocked through the first shut-off device 31. At the same time the second de-energized (and thus open) shut-off device 32 assures that the piston 37 of the differential cylinder is in its appropriate limit position, that is it is in the extended position which is illustrated in FIG. 1.
  • the piston 37 of the differential cylinder 25 is automatically retracted, that is, it assumes the second limit position as soon as the spring 23 of that control valve piston is overcome.
  • This causes the auxiliary servo motor 3 to become hydraulically energized and the main servo motor 2 to become depressurized.
  • the yielding of the respective spring elements 23, which yielding occurs upon blocking of a control valve piston causes a blocking of the second shut-off device 32 after which only the annular chamber 28 of the differential cylinder 25 is pressurized, namely, by the supply pressure of the auxiliary servo motor 3.
  • the auxiliary servo motor 3 whose control valve 11 (particulary the piston thereof) has the same position as that of the main servo motor 2, can take over automatically the driving function when the other is inoperative.
  • a signalling device to the second shut-off device 32.
  • this device is not energized and greater forces than usual must be produced for the control; then this indicates a blocking of the control valve 11 of the auxiliary servo motor 3.
  • the auxiliary servo motor 3 is switched automatically to a pressurized condition since again the pressure on the greater piston surface of the differential cylinder 25 is lacking and the piston 37, when it changes into its second limit position, opens the first shut-off device 31 through its piston rod 29 and the bent lever 30.
  • the described arrangement is not limited to a double hydraulic drive with two simple servo motors.
  • motors can also be used in which three similar operating cylinders are arranged parallel to one another and are provided with a common valve unit.
  • Such servo motors are usually used for controlling the rotor blades of rotarywing aircraft. In such case it will be understood that then at least the aforedescribed linkage is constructed in triplicate.
  • said common control member comprises a pair of levers and pivot connection means thereon positioned adjacent one end and intermediate the ends of each of said pair of levers, said second piston rods being connected to said common control member at said intermediate position whereby a movement of the other end of said control member in one direction will effect a movement of said second piston rods in said direction.
  • first and second pressure source means for supplying pressurized gas to each of said control valves controlling said servomotors, respectively;
  • said change-over valve means further includes first means for effecting a maintaining of one of said control valves in fluid communication with said first pressure source means in response to the fluid pressure in said first pressure source means and for producing a signal in response to a drop in said gas pressure and wherein said means for preventing the operation of one of said servomotors while permitting an operation of the other of said servomotors includes second means for effecting a shut off of the pressurized fluid supply to said one of said control valves in response to said signal and for simultaneously connecting said second pressure source means to the other of said control valves.
  • first and second pressure source means for supplying pressurized fluid to each of said control valves controlling said servomotors, respectively;
  • said change-over means further includes first means for effecting a maintaining of one of said control valves in fluid communication with said first pressure source means in response to said switching means and for producing a signal in response to said flexing of said i'esilient connection beyond said predetermined limit and wherein said means for preventing the operation of one of said servomotors while permitting an operation of the other of said servomotors includes second means for effecting a shut off of the pressurized fluid supply to said one of said control valves in response to said signal and for simultaneously connecting said second pressure source means to the other of said control valves, and said first means including a shut-off valve and differential pressure responsive actuator means.
  • said resilient connection means comprises a pair of lever elements pivotally secured at one end to each of said second piston rods and said control member, each of said levers having means defining an elongated slotlike opening therethrough, the longitudinal axis intersecting the axis of said pivot connection to the respective one of said second piston rods, pin means secured to said second piston rod and received in said elongated slot-like opening, said pin means being longitudinally slidable in said elongated slot-like opening and leaf spring means for resiliently maintaining said pin means in an approximate centrally located position in said elongated slot-like opening whereby a relative movement between said second piston rod and said levers will be resisted by said leaf spring means.
  • each of said servomotors having a first piston rod mounted for reciprocal movement and a control valve for controlling the movement of said first piston rods, each of said control valves having a second piston rod thereon, means for mechanically coupling each of said first piston rods together, a common control member for controlling both of said servomotors, said common control member including means for mechanically coupling said common control member to each of said first piston rods, means for preventing the operation of one of said servomotors while permitting an operation of the other of said servomotors and means for effecting a change-over in operation from one of said servomotors to the other of said servomotors, at least two pressure source means for supplying pressurized fluid to each of said control valves controlling said servomotors, respectively, said means for effecting said changeover including means defining a resilient connection between each of said second piston rods and said common control member and switching means for

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Actuator (AREA)
US227889A 1971-02-23 1972-02-22 Double-hydraulic actuator Expired - Lifetime US3878764A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19712108545 DE2108545C (de) 1971-02-23 Doppelhydraulischer Stellantrieb

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US3878764A true US3878764A (en) 1975-04-22

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US227889A Expired - Lifetime US3878764A (en) 1971-02-23 1972-02-22 Double-hydraulic actuator

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US (1) US3878764A (en:Method)
JP (1) JPS5654280B1 (en:Method)
FR (1) FR2126223B1 (en:Method)
GB (1) GB1386652A (en:Method)
IT (1) IT947773B (en:Method)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4112824A (en) * 1974-10-23 1978-09-12 Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung Double-hydraulic actuator
US4698973A (en) * 1983-08-04 1987-10-13 Johnston Barry W Closed loop solar collector system powering a self-starting uniflow engine
US5701801A (en) * 1995-10-18 1997-12-30 Mcdonnell Douglas Corporation Mechanically redundant actuator assembly

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108343647B (zh) * 2018-01-30 2019-07-26 太原理工大学 一种抗偏载液压滚切式金属板剪切机液压系统

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597419A (en) * 1949-06-02 1952-05-20 Hobson Ltd H M Hydraulic servomotor and the like
US2947285A (en) * 1957-03-20 1960-08-02 Bell Aerospace Corp Manual and automatic hydraulic servomechanism
US3272062A (en) * 1965-10-07 1966-09-13 Ltv Electrosystems Inc Servo valve synchronizer
US3338139A (en) * 1965-12-23 1967-08-29 Bell Aerospace Corp Redundant control system
US3426650A (en) * 1965-12-23 1969-02-11 Bell Aerospace Corp Triple channel redundant hydraeric control system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597419A (en) * 1949-06-02 1952-05-20 Hobson Ltd H M Hydraulic servomotor and the like
US2947285A (en) * 1957-03-20 1960-08-02 Bell Aerospace Corp Manual and automatic hydraulic servomechanism
US3272062A (en) * 1965-10-07 1966-09-13 Ltv Electrosystems Inc Servo valve synchronizer
US3338139A (en) * 1965-12-23 1967-08-29 Bell Aerospace Corp Redundant control system
US3426650A (en) * 1965-12-23 1969-02-11 Bell Aerospace Corp Triple channel redundant hydraeric control system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4112824A (en) * 1974-10-23 1978-09-12 Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung Double-hydraulic actuator
US4698973A (en) * 1983-08-04 1987-10-13 Johnston Barry W Closed loop solar collector system powering a self-starting uniflow engine
US5701801A (en) * 1995-10-18 1997-12-30 Mcdonnell Douglas Corporation Mechanically redundant actuator assembly

Also Published As

Publication number Publication date
FR2126223B1 (en:Method) 1975-02-14
FR2126223A1 (en:Method) 1972-10-06
DE2108545A1 (de) 1972-09-07
DE2108545B2 (de) 1973-01-11
IT947773B (it) 1973-05-30
JPS5654280B1 (en:Method) 1981-12-24
GB1386652A (en) 1975-03-12

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