EP0092972B1 - Hydraulisches Steuersystem - Google Patents

Hydraulisches Steuersystem Download PDF

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Publication number
EP0092972B1
EP0092972B1 EP19830302247 EP83302247A EP0092972B1 EP 0092972 B1 EP0092972 B1 EP 0092972B1 EP 19830302247 EP19830302247 EP 19830302247 EP 83302247 A EP83302247 A EP 83302247A EP 0092972 B1 EP0092972 B1 EP 0092972B1
Authority
EP
European Patent Office
Prior art keywords
actuator
control
valve
valves
hydraulic
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.)
Expired
Application number
EP19830302247
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English (en)
French (fr)
Other versions
EP0092972A3 (en
EP0092972A2 (de
Inventor
Frederick James Fuell
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.)
Claverham Holdings Ltd
Original Assignee
Fairey Hydraulics Ltd
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 Fairey Hydraulics Ltd filed Critical Fairey Hydraulics Ltd
Publication of EP0092972A2 publication Critical patent/EP0092972A2/de
Publication of EP0092972A3 publication Critical patent/EP0092972A3/en
Application granted granted Critical
Publication of EP0092972B1 publication Critical patent/EP0092972B1/de
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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
    • F15B18/00—Parallel arrangements of independent servomotor systems

Definitions

  • This invention relates to hydraulic control systems, using valves to control the supply of hydraulic fluid to an actuator.
  • the invention is concerned with the control of such actuators which are to be used in the positioning of movable loads of substantial size with a high degree of accuracy and reliability.
  • a particular but not exclusive application of such hydraulic control systems is in the control of actuators for use in the power operation of control surfaces of an aircraft.
  • actuators In many applications of hydraulic actuators, it is desirable to position a movable load of some several tonnes with a high degree of accuracy while maintaining a high degree of protection against failure. Many such actuators are required to be controlled remotely by way of electrical signals from a remote control point and it is necessary to provide redundancy to accommodate the failure of various components in the hydraulic system itself or the electrical control system and hydraulic valves associated with it, so that control of the actuator may be maintained in the event of such a failure.
  • One particular, but not exclusive, example of such an actuator is a hydraulic actuator used to effect the movement of an aircraft control surface, particularly a high speed aircraft.
  • a hydraulic control system comprises two actuators operating in parallel or tandem each having a separate supply of hydraulic fluid and a primary and a secondary electrohydraulic servo control valve interposed between each actuator and its respective hydraulic supply, each control valve having two operating coils for the electrical operation thereof, the said coils being connected to four electrical control lanes in such manner that each lane is connected to one coil of a primary control valve associated with one actuator and with one coil of a secondary control valve associated with the other actuator, the primary control valves having a linear input current output flow characteristic passing through the zero current flow point and the secondary control valves have an overlap at the zero flow point such that they provide no flow output for a part of the input current range either side of the zero position.
  • the said overlap at zero flow point is preferably such as to provide no flow output for up to 15% on either side of zero of the input current range.
  • the normal flow gain of each of the secondary control valves having overlap may differ from the normal flow gain of each of the primary valves without overlap such that the full control signal in either sense or direction applied to both types of valve achieves substantially the same maximum flow rate to the respective actuators.
  • the system is preferably provided with means to feed an electrical feedback signal to the said control valves in response to a pressure differential across one and/or the other actuator, and in this arrangement the system is preferably such that a first pressure difference feedback signal generator is provided to give a feedback signal in response to a pressure differential across one actuator and a second pressure generator across the other actuator, each generator giving its feedback signal to the two electrical lanes connected to the primary control valve of its associated actuator.
  • the pressure feedback signal magnitude is preferably arranged to be less than 10% of the valve control current.
  • the actuators in each case may control the supply of hydraulic fluid to a main power actuator. r.
  • the hydraulic control system in the present invention therefore comprises four electrical control lanes each serving in series one of the two coils of one of the valves of each actuator.
  • One such valve which can be regarded as the primary valve in each case, has a nominally zero overlap and high pressure gain and the other, the secondary valve, has a significant overlap and a lower pressure gain.
  • the object of the overlap is to ensure that within the null changes which are to be expected in service, the secondary overlapped low gain valve will remain in the overlap region thus eliminating the parasitic flow which would otherwise arise if the primary valve were standing open in one direction and the secondary valve in the other.
  • Each of the four control lanes is wired in series to a high gain primary valve without overlap of one actuator and the low gain secondary valve of the other.
  • the performance of each actuator is based primarily on the performance of its primary valve, its secondary valve being provided for redundancy and failure survival purposes.
  • one valve associated with an actuator fails mechanically, the presence of another valve associated with that actuator enables the effects of the failed valve to be passivated by opening the second valve in the opposite sense to that in which the first valve is jammed therefore setting up parasitic flow. Control of the system output is then maintained by the other sound actuator.
  • pressure feedback sensing means for example a transducer
  • the pressure feedback means may also be used to identify failures for example mechanical failures in the control valves prior to use of the overall system, for example aircraft, relying on use of the hydraulic control system.
  • the control system of the invention thus utilises a dual valve arrangement associated with each of two actuators to enable the seizure or other defect of any valve to be overcome.
  • two valves electrically in series electronic lane tolerances are distributed equally to the valves in both actuators.
  • pressure feedback sensor to feed a pressure feedback signal into the control lanes and thence to the valves associated with the arrangement of primary and secondary valves described above, residual and electronic and/or mechanical tolerances can be overcome, the overlap/no overlap relationship of the secondary and primary valves respectively enabling antiphase fighting arising from tolerances to be washed out by the action of one valve per actuator despite the equal feeding of the feedback signal into the valves of both actuators.
  • a hydraulic piston and cylinder actuator 10 having a body 11 arranged to be mounted on a structure and an output piston rod 12 arranged to be coupled to a movable element carried on that structure.
  • the hydraulic actuator 10 has in fact two actuators 10A and B arranged back to back, coupled through their piston rods and bodies, but controlled independently of one another.
  • a dual hydraulic supply system (not shown per se) is provided, one system. supplying the actuator 10A through a valve system indicated 14A and the other supplying the actuator 10B through a valve system indicated at 14B.
  • Electrical control input signals may be provided to the valve systems 14A and 14B through four electrical control lanes indicated at 15, 16, 17 and 18 which are each independent of each other.
  • the four lanes 15 to 18 couple the actuator 10 to a control input element (not shown) such as the control column in the pilot's cockpit.
  • each of the electrical supply lanes 15 to 18 is connected to both of the control valve systems 14A and 14B.
  • the system In the event of hydraulic failure in one of actuators 10A or B or their respective hydraulic supply systems, the system may continue to operate under the other actuator and supply system. In the event of failure of two or even perhaps three of the electrical signal lanes, control may still be maintained albeit degraded.
  • each of the valve systems 14A and 14B has a primary hydraulic valve 20 and 25 and a secondary hydraulic valve 21 and 24 so that there are two valve elements to control the flow of hydraulic fluid from each fluid source to the respective actuator 10A or 10B.
  • the two electro hydraulic servo control valves 20 and 21 are arranged to supply the actuator 10A with hydraulic fluid from supply lines 22 connected to a first hydraulic supply system (not shown) having an associated return line 23.
  • the valves 20 and 21 are electrically controlled in a servo system having feedback derived from a position sensor (not shown) responsive to the output position of the hydraulic actuator 10A.
  • Two further electro hydraulic control valves 24 and 25 are similarly arranged to supply fluid from supply lines 26 to the actuator 10B with an associated return line 27.
  • FIG 2A illustrates a steady state situation where no actuator displacement is being demanded e.g. by the pilot.
  • the control valve 20 is assumed to be jammed in a fully open condition allowing full hydraulic pressure P to be applied to one side 40 of the actuator 10A. It will be seen in this situation that the valves 21, 24 and 25 only need to take a very small offset to produce a situation with the full pressure P on the opposite side 43 of the actuator 10B in the second hydraulic system thus preventing displacement of the rod 12.
  • valve 21 When movement is required of the actuator rod 12 with the valve 20 still jammed in the same fully open condition the system compensates by movement of valve 21 as shown to equalise the pressure (at approximately 2P) in the two sides 40 and 41 of actuator 10A leaving actuator 10B to operate normally under control of valves 24 and 25.
  • the valves 24 and 25 will under no load or low load conditions settle so as to provide pressure at approximately zP in both sides 42 and 43 of actuator 10B, movement at maximum rate or close to it of the piston 12 being effected by sufficient relative variation from 2P in sides 42 or 43 to overcome friction etc.
  • At higher load requirements e.g. of a wing surface at high speed will require a greater pressure variation delivered again by appropriate movement of valves 24 and/or 25.
  • pressure P may be in the region of 20 to 30 MN/m 2 , but systems utilizing the present invention may operate at whatever pressure required.
  • pressure P may be in the region of 20 to 30 MN/m 2 , but systems utilizing the present invention may operate at whatever pressure required.
  • Figure 2B when a maximum movement rate is demanded of the actuator 10, near maximum rate will be achieved since the valve 21 will be displaced fully in the sense required to neutralise the effect of the jammed valve 20, whilst the full control condition can be achieved by the valves 24 and 25 operating on the actuator portion 10B.
  • means are provided to measure the differential pressure across each actuator and to feed back to the electro hydraulic control system an electrical signal which is proportional to that pressure difference, substantially to equalise the pressures delivered to each side 40 and 41 of actuator 10A and to each side 42 and 43 of actuator 10B.
  • a feedback signal proportion to that pressure differential will be required to be fed to valves 20 or 21 to restore substantially equality of pressure between sides 40 and 41. Since however the required feedback signal e.g. to valves 20 and/or 21 will be fed equally and in the same sense to valves 24 and/or 25 the objective i.e. equalisation to compensate pressure imbalance cannot be achieved without further provision.
  • the system may be provided with the above described two valve per actuator arrangement using primary and secondary electrohydraulic valves of different overlap characteristics within each of the valve systems 14A and 14B associated with the respective actuators 10A and 10B.
  • the primary valves 20 and 25 have subtantially linear electric current/hydraulic flow characteristics across their centre position, while the secondary valves 21 and 24, have a significant overlap at their centre position so that they do not respond to give hydraulic flow, to signals of say less than 15% of full control signal.
  • a pressure difference feedba g k-signal generator 30 is provided to give a feedback to electrical lanes 15 and 16 in response to the pressure differential between the two sides 40 and 41 of the actuator 10A.
  • a second pressure difference feedback signal generator 31 is arranged to give feedback signals to the lanes 17 and 18 in response to the pressure difference on the two sides of the actuator 10B.
  • the pressure feedback signal magnitude is arranged to be less than 10% of the valve control current then one valve (the primary valve) associated with actuator 10A or 10B will respond to the pressure feedback signal while the other (the secondary valve) will not.
  • the interphase hydraulic control conditions can be offset through the action of primary valves having no overlap, 20 and 25, while the other or secondary valves having overlap, 21 and 24 may be utilised to offset a hard-over condition as previously described.
  • the normal flow gain of the primary valves (20 and 25) and secondary valves (21 and 24) are chosen to be different so that the same full signal level of either sense or direction applied to both types of valves will adhieve essentially the same maximum flow rate out of both types of valve into their respective actuators 10A and 10B.
  • a hard-over condition in one direction in say the valve 20 can still be neutralised by displacement of the valve 21 in the opposite direction when movement is demanded.
  • the invention provides a system which retains full electrical lane redundancy even after one of the hydraulic systems has experienced a failure.
  • the system is also able to neutralise the effect of electric lane tolerances by effecting the command identically to valves associated with the two actuators 10A and 10B by wiring the control coils of the valves in one hydraulic system in series with the coils of the valves of the other hydraulic system.
  • the use of more than one valve per hydraulic system enables a hard-over or other fault condition in one valve to be neutralised by the action of the second valve in the same system.
  • a combination of the above features with the provision of equalising pressure difference feedback signals enables the prevention of hydraulic "fighting" between the two portions of the actuator.
  • the use of valves of different characteristics in each of the two hydraulic systems permits all the features mentioned above to be embodied a at one and the same time.
  • the primary valves 20 and 25 will be axis cut i.e. will be linear across centre with no significant overlap.
  • a valve will have a high pressure gain not less than 28 MN/m 2 per milli amp per coil. It would also have a high band width performance unless special action is taken to reduce the flow gain of the first stage to reduce the overall standing leakage within the system.
  • the secondary valves 21 and 24 would have a normal null bias tolerance of plus or minus 2%. This may deteriorate in service without having a significant effect on the overall behaviour of the system.
  • Deviations in use up to perhaps 7% are believed to be likely, the figure of plus or minus 15% overlap proposed herein being to make allowance for a null bias deterioration of up to plus or minus 10%.
  • a 10% signal for a 28 MN/m 2 differential is appropriate. With this the effect of the pressure feedback will not be significant when applied to the secondary valves and only the primary valves will normally contribute to the equalisation process.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Claims (6)

1. Hydraulisches Steuersystem mit zwei Betätigungseinrichtungen (10A; 10B), die parallel oder auf Tandemweise jeweils eine getrennte Versorgungseinrichtung (22; 26) für hydraulisches Strömungsmittel betätigen und mit einem primären (20; 25) und einem sekundären (21; 24) elektrohydraulischen Servosteuerventil, welches zwischen jeder Betätigungseinrichtung (10A; 10B) und der zugehörigen hydraulischen Versorgungseinrichtung (22; 26) angeordnet ist, wobei jedes Steuerventil zwei Betriebsspulen für deren elektrische Betätigung aufweist, welche Spulen an vier elektrische Steuerstreifen (15-18) auf solche Weise angeschlossen sind, daß jeder Streifen mit einer Spule eines mit einer Betätigungseinrichtung zusammenwirkenden primären Steuerventils und mit einer Spule eines mit der anderen Betätigungseinrichtung zusammenwirkenden sekundären Steuerventils verbunden ist, wobei die primären Steuerventile (20; 25) eine lineare Eingangsstrom-Ausgangsfluß-Charakteristik haben, die durch den Nullstrom-Flußpunkt verläuft und wobei die sekundären Steuerventile (22; 24) am Nullflußpunkt eine Überlappung haben, so daß sie keinen Flußausgang für einen Teil des Eingangsstrombereiches an beiden Seiten der Nullstelle vorsehen.
2. System nach Anspruch 1, dadurch gekennzeichnet, daß die Überlappung des sekundären Ventils am Nullflußpunkt so ist, daß kein Flußausgang für bis zu 15% an beiden Nullseiten des Eingangsstrombereiches vorgesehen wird.
3. System nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Normalflußgewinn jedes sekundären Steuerventils (21; 24) sich vom normalen Flußgewinn jedes der primären Steuerventile (20; 25) unterscheidet, so daß das vollständige Steuersignal in beidem Sinn oder Richtung, aufgebracht auf beide Ventiltypen, im wesentlichen dieselbe maximale Flußrate zu den jeweiligen Betätigungseinrichtungen erzielt.
4. System nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß Mittel (30; 31) vorgesehen sind, um ein elektrisches Rückkopplungssignal zu den Steuerventilen (20, 21; 24, 25) vorzusehen, und zwar in Erwiderung auf eine Druckdifferenz an einer und/oder der anderen Betätigungseinrichtung (10A; 10B).
5. System nach Anspruch 4, dadurch gekennzeichnet, daß ein erster Druckdifferenz-Rückkopplungssignal-Generator (30) vorgesehen ist, um ein Rückkopplungssignal aufgrund eines Druckunterschiedes an einer Betätigungseinrichtung (10A) vorzusehen, und daß ein zweiter Druckgenerator (31) an der anderen Betätigungseinrichtung (10B) vorgesehen ist, daß jeder Generator sein Rückkopplungssignal an die beiden elektrischen Streifen (15-18) abgibt, die an das primäre Steuerventil (20; 25) der zugehörigen Betätigungseinrichtung angeschlossen ist.
6. System nach Anspruch 4 oder 5, dadurch gekennzeichnet, daß die Druck-Rückkopplungssignal-Höhe eingerichtet ist auf weniger als 10% des Ventilsteuerstromes.
EP19830302247 1982-04-22 1983-04-20 Hydraulisches Steuersystem Expired EP0092972B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8211628 1982-04-22
GB8211628 1982-04-22

Publications (3)

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EP0092972A2 EP0092972A2 (de) 1983-11-02
EP0092972A3 EP0092972A3 (en) 1984-05-16
EP0092972B1 true EP0092972B1 (de) 1986-07-30

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EP19830302247 Expired EP0092972B1 (de) 1982-04-22 1983-04-20 Hydraulisches Steuersystem

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DE (1) DE3364878D1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102021214388A1 (de) 2021-12-15 2023-06-15 Zf Friedrichshafen Ag Hydrauliksystem mit wenigstens zwei vorgesteuerten Druckregelventilen

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8426486D0 (en) * 1984-10-19 1984-11-28 Lucas Ind Plc Electro-hydraulic actuator systems
ES2185502B1 (es) * 2001-09-28 2004-08-01 Industria De Turbo Propulsores, S.A. Sistema principal de servo-actuacion de piston con sistema de autocontencion de fallos.
FR2915536B1 (fr) * 2007-04-25 2009-06-05 Michel Cluzeau Dispositif de commande a deux positions "deux sur quatre", 2004.
US20230151829A1 (en) * 2021-11-12 2023-05-18 Woodward, Inc. Hydraulic force fight mitigation
WO2023086556A1 (en) * 2021-11-12 2023-05-19 Woodward, Inc. Hydraulic force fight mitigation

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB940942A (en) * 1960-09-30 1963-11-06 American Brake Shoe Co Hydraulic control apparatus
US3257911A (en) * 1963-08-15 1966-06-28 Moog Inc Fluid powered servomechanism of a redundant, majority voting type
US3915427A (en) * 1973-08-24 1975-10-28 Ltv Aerospace Corp Fluid control system
GB2082799B (en) * 1980-08-27 1983-11-23 Elliott Brothers London Ltd Hydraulic actuator systems

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102021214388A1 (de) 2021-12-15 2023-06-15 Zf Friedrichshafen Ag Hydrauliksystem mit wenigstens zwei vorgesteuerten Druckregelventilen

Also Published As

Publication number Publication date
DE3364878D1 (en) 1986-09-04
EP0092972A3 (en) 1984-05-16
EP0092972A2 (de) 1983-11-02

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