Double hydraulic valve of a servo-control for feathering the blades of a rotorcraft rotor

Abstract

A hydraulic valve (3, 3) of a servo-control for feathering the blades (1) of a rotorcraft rotor. The hydraulic valve (3, 3) comprises a main valve member (5) and an emergency valve member (6) blocked relative to a valve cylinder (4) of the hydraulic valve (3, 3) by means of a pin (23) in sliding thrust engagement in a cavity (24) of the emergency valve member (6). Relative movement between the emergency valve member (6) and the valve cylinder (4) initiating sliding movement of the pin (23) inside the cavity (24) and causing mover means (27) for moving the pin (23) to be put into operation, thereby releasing the emergency valve member (6) to move freely.

Claims

1. A double hydraulic valve of a servo-control for feathering the blades of a rotorcraft rotor, the hydraulic valve comprising: a valve cylinder having A ducts dedicated to providing a hydraulic connection between the hydraulic valve and a source of fluid under pressure, the A ducts comprising at least an admission A duct providing fluid admission from the outside to the inside of the hydraulic valve and at least one discharge A duct providing fluid discharge out from the hydraulic valve, the valve cylinder having B ducts dedicated to providing a hydraulic junction between the hydraulic valve and a cylinder of a hydraulic actuator of the servo-control, referred to as the actuator cylinder, the B ducts comprising a pair of B ducts providing fluid flow between the inside and the outside of the hydraulic valve; a main valve member movably mounted inside the valve cylinder and controllable by a control member, the main valve member providing A channels dedicated to fluid flow through the hydraulic valve between the A ducts and the B ducts, the admission A duct and the discharge A duct being in fluid flow communication via A channels selectively with one or the other of the B ducts depending on the respective positions of the main valve member inside the valve cylinder; an emergency valve member interposed between the valve cylinder and the main valve member, the emergency valve member movably housing the main valve member and being movably mounted inside the valve cylinder, the emergency valve member having B channels that are dedicated to fluid flow between the A channels and either the A ducts or the B ducts, selectively depending on the respective positions of the main valve member; and positioning means for positioning the emergency valve member in a predefined position inside the valve cylinder, in which predefined position the emergency valve member, the A channels, and the B channels are in fluid flow communication in pairs, the positioning means making use at least of elastically deformable means bearing against the valve cylinder, the emergency valve member being authorized to move inside the valve cylinder together with the main valve member under the effect of the emergency valve member being entrained by friction from the main valve member in the event of it seizing inside the emergency valve member against thrust exerted by the elastically deformable means; wherein said positioning means are means for blocking the emergency valve member against the valve cylinder by a pin mounted to move relative to the valve cylinder and co-operating by sliding thrust engagement with a cavity of the emergency valve member, the pin being movable between an engaged position in which a head of the pin is received in the cavity under the effect of the thrust exerted against the pin by the elastically deformable means, and a disengaged position in which said head is totally disengaged from the cavity by mover means for causing the pin to move against the thrust exerted on the pin by the elastically deformable means, operation of the mover means depending on relative movement between the emergency valve member and the valve cylinder serving to release at least in part said cavity by the head of the pin sliding inside the cavity; wherein the mover means for moving the pin are means for applying fluid thrust to the pin, which is provided with a piston having applied thereagainst the fluid that is admitted under pressure into the inside of the hydraulic valve.

2. A hydraulic valve according to claim 1, wherein the pin is movably received in a chamber of the valve cylinder and is arranged as a plunger for closing a first fluid passage referred to as a C channel, opening out into the chamber through the cavity and being in fluid flow communication with any one of said A ducts and B ducts, and at least a partial setback in the cavity allowing fluid to be admitted into the inside of the chamber from the C channel.

3. A hydraulic valve according to claim 2, wherein the C channel is in fluid flow communication with the admission A duct.

4. A hydraulic valve according to claim 2, wherein the chamber is in fluid flow communication with the discharge A duct via a third fluid comprising an E channel, said E channel opening out into any position of the pin upstream from the piston in the travel direction of the pin from the engaged position towards the disengaged position.

5. A hydraulic valve according to claim 4, wherein the E channel includes a section constriction.

6. A hydraulic valve according to claim 1, wherein the hydraulic valve has means for establishing fluid flow communication between all of the A ducts and the B ducts in the disengaged position of the pin.

7. A hydraulic valve according to claim 6, wherein the valve cylinder has second fluid passages comprising D channels, said D channels being fluid passages respectively for a first D channel between the chamber and the admission A duct, for a second D channel between the chamber and the discharge A duct, for a third D channel between the chamber and one of the B ducts, and for a fourth D channel between the chamber and the other one of the B channels, the outlet to the chamber of the D channels being closed off jointly by the piston in the engaged position of the pin and being uncovered by the piston in the disengaged position of the pin.

8. A hydraulic valve according to claim 7, wherein the D channels open out into the chamber in a common radial plane considered to be inside the chamber relative to the axial travel direction of the pin, fluid flow communication being established between all of the A ducts and the B ducts simultaneously.

9. A hydraulic valve according to claim 7, wherein the D channels open out into the chamber in different radial planes relative to the travel direction of the pin inside the chamber, fluid flow communication being established progressively between all of the A ducts and the B ducts.

10. A hydraulic valve according to claim 1, wherein the hydraulic valve includes means for holding the pin in the disengaged position independently of any interruption in the operation of the mover means, wherein the means for holding the pin comprises the elastically deformable means.

11. A hydraulic valve according to claim 10, wherein the elastically deformable means is arranged as at least one spring blade, said spring blade(s) being fastened to the valve cylinder and being bidirectionally engaged with the pin, the spring blade(s) exerting thrust against the pin in the engaged position and traction on the pin in the disengaged position as a result of its deformation caused by the pin passing into the disengaged position.

12. A hydraulic valve according to claim 10, wherein the holder means are of the resilient engagement type and comprise an elastically deformable clip co-operating with a housing, the clip and the housing being arranged respectively one in or on the valve cylinder and the other in or on the pin.

13. A hydraulic valve according to claim 1, wherein the hydraulic valve is of the slide type, the main valve member and the emergency valve member being mounted to move in translation inside the valve cylinder.

14. A hydraulic valve according to claim 1, wherein the hydraulic valve is of the rotary type, the main valve member and the emergency valve member being mounted to move angularly inside the valve cylinder.

15. A hydraulic valve according to claim 1, wherein the bearing surface of the head of the pin for bearing against the inside of the cavity is a spherical bearing surface.

16. A hydraulic valve according to claim 1, wherein the operation of the mover means depends on detecting relative movement between the main valve member and the emergency valve member.

17. A servo-control for feathering the blades of a rotorcraft rotor the servo-control including at least one hydraulic actuator having at least one double-acting actuator cylinder and at least one hydraulic valve according to claim 1.

18. A servo-control according to claim 17, the servo-control comprising at least one hydraulic actuator having a plurality of double-acting actuator cylinders, each of the actuator cylinders being fed with fluid by a hydraulic valve associated therewith.

19. A servo-control according to claim 18, the servo-control comprising at least one double-acting hydraulic actuator having two actuator cylinders wherein: each actuator cylinder of the hydraulic actuator is in fluid flow communication with a hydraulic valve associated therewith, the B ducts of each of the hydraulic valves being in fluid flow communication with a respective actuator cylinder; one of the B ducts of a first hydraulic valve being in fluid flow communication with a first top passage of a first actuator cylinder and the other B duct of the first hydraulic valve being in fluid flow communication with a first bottom passage of the first actuator cylinder; one of the B ducts of a second hydraulic valve being in fluid flow communication with a second top passage of a second actuator cylinder, and the other B duct of the second hydraulic valve being in fluid flow communication with a second bottom passage of the second actuator cylinder; and the main valve members of each of the hydraulic valves being jointly engaged with a common control member that when operated governs the distribution of fluid through the two hydraulic valves.

20. A servo-control according to claim 19, in which servo-control the actuator cylinders of the hydraulic actuator are mounted in tandem, together housing a common rod.

21. A servo-control according to claim 19, in which servo-control the actuator cylinders of the hydraulic actuator are mounted in parallel, the actuator cylinders housing respective rods that are mechanically connected together.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Embodiments of the present invention are described with reference to the figures of the accompanying sheets, in which:

(2) FIG. 1 shows a servo-control for feathering the blades of a rotorcraft rotor, the servo-control incorporating a hydraulic valve in accordance with the present invention;

(3) FIGS. 2 to 4 illustrate respective embodiments of a servo-control incorporating at least one hydraulic valve in accordance with the present invention;

(4) FIGS. 5 to 8 are diagrams showing successive ways of operating a hydraulic valve included in the various servo-controls shown in FIGS. 2 to 4; and

(5) FIGS. 9 and 10 show respective variant embodiments of a hydraulic valve in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) In FIGS. 1 to 4, a servo-control is arranged to feather the blades 1 of a main rotor of a rotorcraft, the rotor being of substantially vertical axis.

(7) The servo-control conventionally associates at least one hydraulic actuator 2 of operation governed by at least one hydraulic valve 3, 3 comprising a valve cylinder 4 housing a main valve member 5 and an emergency valve member 6.

(8) The hydraulic actuator 2 comprises at least one actuator cylinder 7, 8 housing a rod 9 that is axially movable along the general direction in which the actuator cylinder 7, 8 extends. Each actuator cylinder 7, 8 is a double-acting cylinder, having for this purpose a top passage 10 and a bottom passage 11 to allow a fluid to flow inside the actuator cylinder(s) 7, 8.

(9) The fluid is brought under pressure to the actuator cylinder(s) 7, 8 and is potentially admitted into the actuator cylinder(s) 7, 8 either via the top passage 10 or via the bottom passage 11. Conversely, fluid is discharged from the actuator cylinder(s) 7, 8 through the bottom passage 11 or through the top passage 10.

(10) The flow of fluid inside the actuator cylinder(s) 7, 8 causes the rod 9 to move relative to the actuator cylinder(s) 7, 8, which rod is slidably mounted inside at least one of the actuator cylinder(s) 7, 8 to move in two opposite directions. Relative movement between the actuator cylinder(s) 7, 8 and the rod 9 is used for feathering the blades 1.

(11) To this end, the actuator cylinder(s) 7, 8 and the rod(s) 9 of the hydraulic actuator(s) 2 are each provided with respective attachment members 12, 13 enabling them to be engaged respectively on a structure of the rotorcraft and/or on a blade feathering member 14.

(12) In FIGS. 1 to 3, the rod 9 has an attachment member 13 for attaching to the structure of the rotorcraft and the actuator cylinder 7 is fitted with an attachment member 12 for attaching to the blade feathering member 14.

(13) In FIG. 4, the rods 9 co-operating with respective actuator cylinders 7, 8 are jointly fitted with a common attachment member 12 for attaching to the blade feathering member 14. The actuator cylinders 7, 8 are fitted with respective attachment members 13 for attaching to the structure of the rotorcraft.

(14) Furthermore, in FIGS. 1 and 2, the servo-control has a hydraulic actuator 2 with a single actuator cylinder 7. In FIG. 3, the servo-control has a hydraulic actuator 2 with two actuator cylinders 7, 8 connected in tandem and housing a common rod 9. In FIG. 4, the servo-control has a hydraulic actuator 2 with two actuator cylinders 7, 8 arranged in parallel, with their respective rods 9 being operated jointly and being connected together by means of the common attachment member 12 with which they are fitted.

(15) In general in FIGS. 1 to 4, the flow of fluid through at least one actuator cylinder 7, 8 is governed by a hydraulic valve 3, 3 that is associated therewith.

(16) The operation of at least one hydraulic valve 3, 3 depends on a control member 15 that is operable by a pilot of the rotorcraft, which pilot may be a human or an autopilot. The control member 15 is engaged on the main valve member 5 of at least one hydraulic valve 3, 3 in order to govern the flow of fluid between said at least one actuator cylinder 7, 8 and a fluid source 16.

(17) The valve cylinder 4 of a hydraulic valve 3, 3 of the invention has A ducts 17, 17 dedicated to making a hydraulic connection between the hydraulic valve 3, 3 and the fluid source 16. A pipe referred to as the go A pipe 18 acts via a pump 16 to convey the fluid under pressure from the fluid source 16 to an admission A duct 17 of the hydraulic valve 3, 3. Another pipe, referred to as the return A pipe 18 conveys fluid under pressure from discharge A ducts 17 of the hydraulic valve 3, 3 to the fluid source 16.

(18) The valve cylinder 4 of a hydraulic valve 3, 3 of the invention also has B ducts 19, 19 for providing a hydraulic connection between the hydraulic valve 3, 3 and an actuator cylinder 7, 8 with which it is associated. The B ducts are in hydraulic communication via pipes 20, 20, referred to as B pipes, respectively with the top and bottom passages 10, 11 of the hydraulic cylinder 7, 8 with which the hydraulic valve 3, 3 is associated.

(19) There can also be seen a first B pipe referred to as a top B pipe 20 and a second B pipe referred to as a bottom B pipe 20, the top and bottom B pipes 20 and 20 being in fluid flow communication respectively with the top passage 10 and the bottom passage 11 of the actuator cylinder 7, 8 with which the B pipes are associated.

(20) The main valve member 5 of a hydraulic valve 3, 3 is mounted to slide inside the emergency valve member 6, which is itself mounted to slide inside the valve cylinder 4.

(21) In the event of the main valve member 5 seizing inside the emergency valve member 6, then the main valve member 5 entrains the emergency valve 6 by friction so that it slides inside the valve cylinder 4 in order to keep the hydraulic valve 3, 3 in operation.

(22) The main valve member 5 has first channels 21, 21 that are referred to as A channels, being dedicated to conveying fluid through the hydraulic valve 3, 3 between the A ducts 17, 17 and the B ducts 19, 19.

(23) In the embodiment shown, the A channels 21, 21 are formed by respective enclosures opening out to the periphery of the main valve member 5 via the recess in the emergency valve member 6 that houses the main valve member 5.

(24) Furthermore, the emergency valve member 6 has second channels 22-22d (22, 22a, 22b, 22c, 22d) referred to as B channels. The B channels 22-22d are for conveying fluid flow between the A ducts 17, 17 and the B ducts 19, 19 via the A channels 21, 21. The flow of fluid between the A ducts 17, 17 and the B ducts 19, 19 is obtained selectively depending on the various respective positions of the main valve member 5 operated by the control member 15.

(25) Other than in the event of the main valve member 5 seizing, the emergency valve member 6 is held in a predefined position inside the valve cylinder 4. For this purpose, the emergency valve member 6 is blocked relative to the valve cylinder 4 by means of a pin 23. The pin 23 is mounted to move axially inside the valve cylinder 4 and it co-operates by sliding thrust engagement with a cavity 24 formed in the emergency valve member 6.

(26) The direction in which the pin 23 moves axially extends transversely, and more specifically orthogonally, relative to the axis along which the emergency valve member 6 moves so that the forced blocking the emergency valve member 6 relative to the valve cylinder 4 is optimized.

(27) More particularly, the pin 23 has a head 25 of spherical or analogous shape providing said sliding thrust engagement between the head 25 and the inside of the cavity 24. The pin 23 is held in the engaged position by close co-operation between the head 25 and the cavity 24, as shown in FIGS. 1 to 5.

(28) The pin 23 is held in the engaged position under the effect of thrust exerted by elastically deformable means 26 thrusting in opposite directions against the valve cylinder 4 and against the pin 23. Said opposite thrust acts axially along the general axis along which the pin 23 extends and moves inside the valve cylinder 4.

(29) In the event of the main valve member 5 seizing inside the emergency valve member 6, the emergency valve member 6 being entrained by the main valve member 5 causes the head 25 to slide inside the cavity 24.

(30) Such relative sliding between the head 25 and the cavity 24 is representative of the main valve member 5 seizing inside the emergency valve member 6 and it takes place at a predetermined force threshold for relative movement between the emergency valve member 6 and the valve cylinder 4.

(31) Said force threshold is predetermined depending on the friction forces between the emergency valve member 6 and the valve cylinder 4, depending on the thrust force exerted against the pin 23 by the elastically deformable means 26, and depending on the surface state of the shape of the sliding thrust surface of the head 25 against the cavity 24, said thrust surface preferably being a spherical bearing surface.

(32) Once movement of the emergency valve member 6 has been initiated, mover means 27 for moving the pin 23 are put into operation. The pin 23 is moved inside the valve cylinder 4 from the engaged position to a disengaged position in which the pin 23 is completely released from any engagement with the cavity 24.

(33) In FIGS. 1 and 10, the pin 23 is held in the engaged position inside the cavity 24 by elastically deformable means 26 formed by a compression spring, for example. In FIGS. 2 to 9, the pin 23 is held in the engaged position inside the cavity 24 by elastically deformable means 26 formed by spring blade(s).

(34) In FIG. 1, a movement of the emergency valve member 6 inside the valve cylinder 4 gives rise to relative sliding between the head 25 and the cavity 24, and this movement is detected by detector means 28 that cause the mover means 27 to be put into operation.

(35) By way of example, the detector means 28 are means for detecting the beginning of relative movement between the emergency valve member 6 and the valve cylinder 4 under the effect of the main valve member 5 seizing and entraining the emergency valve member 6 by friction. The mover means 27 may potentially be any type of means suitable for moving the pin 23, e.g. means of the mechanical type, of the electromagnetic type, of the pneumatic type, or of the chemical type.

(36) In FIGS. 2 to 10, advantage is advantageously taken of the flow of fluid under pressure inside the valve to constitute the mover means 27. More particularly, the cavity 24 is formed at the outlet of a channel 29 referred to as a C channel, forming a first fluid passage between any of the A ducts 17, 17 or B ducts 19, 19 and a chamber 30 arranged inside the valve cylinder 4. The pin 23 has a piston 31 and said chamber 30 is a chamber for guiding the pin 23 in sliding towards the disengaged position, with the sliding of the pin 23 being caused under the effect of the fluid under pressure being admitted into the inside of the chamber 30 via the C channel 29, and preferably via the A channels 21, 21 in order to simplify the structural layout of the hydraulic valve 3, 3.

(37) More particularly in FIG. 5, the pin 23 is held in the engaged position by the elastically deformable means 26 formed by the spring blade(s) applying axial thrust against the pin 23 towards the emergency valve member 6. The head 25 is held pressed against the cavity 24 by closing the C channel 29. Other than in the event of the main valve member 5 seizing, the emergency valve member 6 is blocked in position by the head 25 and the cavity 24 co-operating by mutual engagement.

(38) In FIG. 6, in the event of the main valve member 5 seizing, the emergency valve member 6 tends to be entrained to slide inside the valve cylinder 4 by the main valve member 5. Regardless of how small the amplitude of such a movement of the emergency valve member 6 might be, this movement causes the head 25 to slide inside the cavity 24 into an intermediate position of the pin 23.

(39) In the intermediate position of the pin 23, the head 25 is held engaged inside the cavity 24 being partially released from the engagement between the cavity 24 and the pin 23. Since the pin 23 is slidably engaged inside the cavity 24 via the head 25, the emergency valve member 6 is held in the intermediate position of the pin 23 while it is prevented from moving in part relative to the valve cylinder 4. Such partial prevention of movement is considered to be floating because of the relative sliding caused between the cavity 24 and the head 25.

(40) In the intermediate position of the pin 23, admission of fluid from the C channel 29 into the inside of the chamber 30 is allowed. The fluid admitted into the inside of the chamber 30 pushes the pin 23 back into the disengaged position, in which disengagement position the head 25 is placed totally outside the cavity 24, as shown in FIG. 7.

(41) In FIGS. 7 and 8, blocking of the emergency valve member 6 relative to the valve cylinder 4 is inhibited because the pin 23 has passed into the disengaged position.

(42) With reference to FIGS. 2 to 10 as a whole, the valve cylinder 4 includes a fluid passage referred to as an E channel 33 that opens out upstream from the piston 31 in the travel direction of the pin 23 from the engaged position towards the disengaged position. The E channel 33 is a channel providing connection between the chamber 30 and the discharge A duct 17 so as to allow fluid from the C channel 29 in the engaged position of the pin 23 inside the cavity 24 to escape, should that be necessary. Such an escape of fluid might be the result of an unwanted source of leakage between the cavity 24 and the head 25.

(43) It should also be observed that the fluid flowing inside the discharge A duct 17 is at a pressure lower than the pressure of the fluid flowing in the admission A duct 17. Such a pressure difference is induced, for example, by the return A pipe 18 towards the fluid source 16 being connected to the open air, or at least by the discharge A duct being pressurized at a pressure lower than that of the fluid admitted under pressure into the hydraulic valve 3, 3 by means of the pump 14.

(44) Admitting fluid into the chamber 30 via the E channel 33 serves to lubricate the chamber 30 and avoids any excessive rise in pressure inside the chamber 30 upstream from the piston 31 in the flow direction of the fluid admitted into the chamber 30 from the C channel 29.

(45) Furthermore, D channels 32 are arranged in the valve cylinder 4 between the chamber 30 and respective ones of the A ducts 17, 17 and the B ducts 19, 19. In the engaged position of the pin 23, as shown in FIGS. 2 to 5, the D channels 32 are shut off by the piston 31 so that the admission of fluid into the inside of the D channels 32 is not effective.

(46) In FIGS. 2 to 8, the D channels 32 open out into the chamber 30 in a common radial plane R. In FIG. 9, the D channels 32 in communication with the A ducts 17, 17 and the D channels in communication with the B ducts open out into the chamber 30 in respective radial planes R1 and R2.

(47) More particularly, the D channels 32 in communication with the A ducts 17, 17 open out into the chamber 30 in a first radial plane R1 and the D channels 32 in communication with the B ducts 19, 19 open out into the chamber 30 in a second radial plane R2. The first radial plane R1 is preferably upstream from the second radial plane R2 in the flow direction of the fluid admitted into the chamber 30 from the C channel 29.

(48) Each hydraulic valve 3, 3 is fitted with holder means for holding the pin 23 in the disengaged position independently of any interruption in the operation of the mover means 27.

(49) In FIGS. 2 to 9, said holder means are formed by the spring blade(s) 26. In the disengaged position of the pin 23, the spring blade(s) 26 is/are put back by the pin 23 causing it to become deformed with curvature that is the reverse of its initial curvature in the engaged position of the pin 23. In this inverted curvature position, the spring blade(s) exert(s) a traction force on the pin 23 in the direction opposite to the thrust direction in which force was exerted on the pin 23 when in the engaged position.

(50) In FIG. 10, said holder means are formed by an elastically deformable clip 34 arranged on the valve cylinder 4, the clip 34 controlling by engaging in a housing 35 formed in the pin 23.

(51) In FIGS. 5 to 10, the E channel 33 is in fluid flow communication with the chamber 30 and it is appropriate to prevent the fluid admitted under pressure into the chamber 30 being admitted into the E channel 33 via the C channel 29 in the disengaged position of the pin 23. For this purpose, it is proposed to provide a constriction 36 in the E channel 33.

(52) Such a constriction 36 allows the escape of any fluid that might be admitted accidentally into the inside of the chamber 30 under the effect of a said leakage source between the head 25 and the cavity 24. Nevertheless, the constriction 36 serves to increase the head loss needed for discharging from the chamber 30 any fluid that is admitted under pressure from the admission A channel into the chamber 30 via the E channel 33.

(53) In the disengaged position of the pin 23, the D channels 32 are in fluid flow communication with the chamber 30. As a result, the A ducts 17, 17 and the B ducts 19, 19 are in fluid flow communication with one another, thereby having the effect of rendering inoperative the fluid pressure exerted on either side of the rod 9 co-operating with the actuator cylinder 7, 8 associated with hydraulic valve 3, 3.

(54) In the event of a servo-control including a hydraulic actuator 2 having a single actuator cylinder 7, as shown in FIGS. 1 and 2, mechanical connection means 37 provide direct mechanical connection between the valve control member 15 and the blade feathering member 14, such that the blade 1 can be controlled directly by the valve control member 15 so as to avoid making use of a faulty servo-control.

(55) Such mechanical connection means 37 may potentially be operated by the human pilot of the rotorcraft, or they may be put into operation spontaneously, depending on a sensor 38 for sensing that the fluid pressure exerted on either side of the rod 9 is ineffective. By way of example, such a sensor 38 may be formed by means for measuring the pressure of fluid flowing through the B pipes 20, 20.

(56) With a servo-control having a hydraulic actuator 2 with multiple actuator cylinders 7, 8, failure of the fluid pressure exerted on either side of the rod 9 co-operating with one of the actuator cylinders 7, 8 does not prevent a movement being performed by the control member 15 of the main valve member 5 of another hydraulic valve associated with another actuator cylinder 7, 8. It should be understood that these arrangements are applicable regardless of the arrangement of the hydraulic actuator 2, i.e. regardless of whether the actuator cylinders 7, 8 are mounted in tandem as shown in FIG. 3 or are mounted in parallel as shown in FIG. 4.

(57) The ways in which the pin is moved as shown in FIGS. 5 to 10 in the context of the hydraulic type mover means making use of the fluid admitted under pressure into the inside of the hydraulic valve 3, 3 can be transposed by substitution without any particular effort to a hydraulic valve as shown in FIG. 1, in which the mover means are of any other type.

(58) The hydraulic valves 3, 3 shown by way of example in the figures are of the slider type, with the main valve member 5 and the emergency valve member 6 being mounted to slide inside the valve cylinder 4. Nevertheless, it should be understood that the rules set out for the present invention can be transposed without any particular effort to hydraulic valves 3, 3 of the rotary type, in which the main valve member 5 and the emergency valve member 6 are mounted to turn inside the valve cylinder 4.

(59) The general axis along which the pin 23 extends and moves, and by way of corollary the direction of the thrust and/or fraction exerted by the elastically deformable means 26 on the pin 23 extend transversely to the axis along which the main valve member 5 and the emergency valve member 6 move.

(60) Arranging for the pin 23 to move in this way makes it easy to apply the invention to a hydraulic valve of any slide type or of any rotary type. The ways in which the main valve member 5 and the emergency valve member 6 move in sliding or in turning inside the valve cylinder 4 of the hydraulic valve 3, 3 have no effect on the conditions for using and moving the pin 23 either to block the emergency valve member 6 relative to the valve cylinder 4 by pin engagement, or on the contrary to inhibit such blocking.