DUPLICATED HYDRAULIC CIRCUIT WITH PRESSURE REGULATION

Abstract

The present invention relates to A device for supplying hydraulic power, the device comprising two hydraulic circuits jointly feeding multi-cylinder hydraulic power transmission means in which each cylinder is connected to a single one of the hydraulic circuits independently of the others. Each hydraulic circuit includes a hydraulic pressure and flow rate generator and a pressure control module controlling said hydraulic pressure and flow rate generator so as to regulate the pressure of said fluid flowing in said hydraulic circuit as a function of said pressure of said fluid flowing in each hydraulic circuit and possibly as a function of one or more parameters external to said device.

Claims

1. A hydraulic circuit for feeding at least one hydraulic receiver, the hydraulic circuit comprising: a fluid; a hydraulic pressure and flow rate generator for generating hydraulic pressure and flow rate in the fluid; pipes for connecting the hydraulic pressure and flow rate generator with the hydraulic receiver; and a pressure control module controlling the hydraulic pressure and flow rate generator to regulate the pressure of the fluid flowing in the hydraulic circuit as a function of the pressure of the fluid flowing in the hydraulic circuit and of one or more parameters external to the hydraulic circuit so that a pressure of the fluid flowing in the hydraulic circuit is equal to a setpoint pressure; wherein the pressure control module comprises a first actuator that is hydraulic and controlled at least in part as a function of the pressure of the fluid flowing in the hydraulic circuit, at least one second actuator that is controlled by one or more parameters external to the hydraulic circuit, and calibration means.

2. A hydraulic circuit according to claim 1, wherein the hydraulic first actuator has a first movable element on which the pressure of the fluid flowing in the hydraulic circuit is applied at least in part in order to generate a first force F1 balanced by a second force F2 generated by the calibration means, each second actuator enabling the setpoint pressure to be modified.

3. A hydraulic circuit according to claim 1, wherein a second actuator modifies the calibration setting of the calibration means.

4. A hydraulic circuit according to claim 1, wherein a second actuator generates a third force F3 and drives movement of the first movable element of the first actuator.

5. A hydraulic circuit according to claim 1, wherein a second actuator is a hydraulic actuator fed by a second fluid external to the hydraulic circuit, the second actuator being connected to a hydraulic system external to the hydraulic circuit by a pipe of the hydraulic circuit in which there flows the fluid external to the hydraulic circuit.

6. A hydraulic circuit according to claim 1, wherein a second actuator is an electric actuator controlled by a control signal corresponding to one or more parameters external to the hydraulic circuit, the hydraulic circuit having an electrical connection connecting the second actuator to a control device external to the hydraulic circuit and in which the control signal passes.

7. A hydraulic circuit according to claim 1, wherein the second actuator is movement controlled.

8. A hydraulic circuit according to claim 1, wherein the second actuator is force controlled.

9. A hydraulic circuit according to claim 1, wherein the calibration means comprise resilient means.

10. A hydraulic circuit according to claim 1, wherein each second actuator includes braking and damping means for stabilizing the operation of the pressure control module.

11. A hydraulic circuit according to claim 1, wherein a parameter external to the hydraulic circuit is selected from a list comprising: a second pressure of a second fluid flowing in another hydraulic circuit; an operating characteristic of a hydraulic receiver fed by the hydraulic circuit; and an order to modify the setpoint pressure.

12. A hydraulic power supply device comprising at least one hydraulic receiver and at least two hydraulic circuits, the hydraulic circuits jointly feeding the hydraulic receiver with fluid under pressure, wherein each hydraulic circuit is a circuit according to claim 1.

13. A device according to claim 12, wherein the hydraulic receiver includes multi-cylinder hydraulic power transmission means comprising a plurality of cylinders, each cylinder of the hydraulic power transmission means being connected to a single hydraulic circuit independently of every other hydraulic circuit, the pressure of the fluid flowing in each hydraulic circuit acting on a respective one of the cylinders, the hydraulic power transmission means being capable of supplying an operating force as a function of the pressures of the hydraulic circuits and equal to a setpoint force Fc, the setpoint pressure of each hydraulic circuit being defined as a function of the setpoint force Fc.

14. A device according to claim 12, wherein the hydraulic circuits are segregated both hydraulically and mechanically, firstly so as to prevent any exchange of fluid between the hydraulic circuits, and secondly so that the hydraulic circuits are structurally distinct.

15. A device according to claim 12, wherein a second hydraulic actuator of a first hydraulic circuit includes braking and damping means, and the braking and damping means characterize a pressure threshold applied to a second pressure of a second fluid flowing in a second hydraulic circuit and feeding the second actuator so as limit the effects of the second actuator on the modification of the setpoint pressure of the first fluid flowing in the first hydraulic circuit.

16. A device according to claim 12, wherein the hydraulic power transmission means comprise control means for controlling a movable airfoil element of an aircraft, and a parameter external to a first hydraulic circuit is selected from the list comprising: a second pressure of a second fluid flowing in a second hydraulic circuit of the hydraulic power supply device; a type of mission being undertaken by the aircraft; a region of a flight envelope of the aircraft; an action of a pilot of the aircraft on a flight control of the aircraft; a control order from the pilot seeking to modify the setpoint pressure of the first fluid flowing in the first hydraulic circuit; and a parameter external to the aircraft (50) and likely to vary.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0099] The invention and its advantages appear in greater detail from the context of the following description of embodiments given by way of example and with reference to the accompanying figures, in which:

[0100] FIG. 1 shows a rotary wing aircraft having a hydraulic power supply device of the invention;

[0101] FIGS. 2 to 9 show various embodiments of such a hydraulic power supply device; and

[0102] FIGS. 10 and 11 show a hydraulic circuit of the invention.

[0103] Elements present in more than one of the figures are given the same references in each of them.

DETAILED DESCRIPTION OF THE INVENTION

[0104] FIG. 1 shows a rotary wing aircraft 50 comprising a fuselage 51 and a tail boom 57 fastened at a first end to the fuselage 51. The rotary wing aircraft 50 also has a main rotor 52 arranged above the fuselage 51 and provided with main blades 54, together with an anti-torque secondary rotor 53 arranged at a second end of the tail boom 57 and provided with secondary blades 55. The main blades 54 and the secondary blades 55 constitute movable airfoil elements of the aircraft 50. Finally, the aircraft 50 has a hydraulic power supply device 1 provided with two hydraulic circuits 10 and 20 and with a hydraulic receiver 3. The hydraulic receiver 3 has two valves 31 and 32, and control means 4 for controlling the pitch of the main blades 54 so as to modify their pitch.

[0105] Various examples of hydraulic power supply devices 1 are shown in FIGS. 2 to 9.

[0106] In common manner, these hydraulic power supply devices 1 have one hydraulic receiver 3 and two hydraulic circuits 10 and 20 jointly feeding the hydraulic receiver 3 with fluid under pressure. Each hydraulic circuit 10, 20 comprises a generator 11, 21 of hydraulic pressure and flow rate in a fluid, pipes 12, 22 and a pressure control module 13, 23. The pipes 12, 22 connect the hydraulic pressure and flow generator 11, 21 to the hydraulic receiver 3 and they feed it with fluid under pressure.

[0107] The pressure control module 13, 23 of a first hydraulic circuit 10, 20 controls the hydraulic pressure and flow rate generator 11, 12 of the first hydraulic circuit 10, 20 in order to regulate the pressure of the fluid flowing in the first hydraulic circuit 10, 20 as a function of the pressure of the fluid flowing in this first hydraulic circuit 10, 20 and of one or more parameters external to the first hydraulic circuit 10, 20 so that the pressure of the fluid flowing in the first hydraulic circuit 10, 20 is equal to a setpoint pressure.

[0108] The hydraulic receiver 3 has two valves 31, 32 and control means 4 serving to modify the pitch of the main blades 54 of the main rotor 52. Each valve 31, 32 is connected to a hydraulic circuit 10, 20 and controls the feed of fluid to the control means 4 as a function of a control order. By way of example, the control order may come from a flight control present in the aircraft 50 and operated by a pilot.

[0109] The control means 4 comprise two-cylinder hydraulic power transmission means, such as a duplex servo. Each valve 31, 32 feeds a single cylinder 41, 42 of the control means 4. Both of the valves 31, 32 are controlled simultaneously and the two cylinders 41, 42 are fed simultaneously by the two hydraulic circuits 10 and 20 so as to cause an operating force F.sub.SV to appear on the rod 45 of the control means 4. The operating force F.sub.SV serves to modify the pitch of the main blades 54. This operating force F.sub.SV is a function firstly of the pressure P.sub.10, P.sub.20 of the fluid flowing respectively in each hydraulic circuit 10, 20 and of the surface area S.sub.43, S.sub.44 of a piston 43, 44 arranged respectively in each cylinder 41, 42 and secured to the rod 45. It is thus possible to write:

F.sub.SV=P.sub.10.Math.S.sub.43+P.sub.20.Math.S.sub.44

[0110] Furthermore, this operating force F.sub.SV is equal to a setpoint force Fc in order to guarantee that this operating force F.sub.SV is greater than or equal to the force needed to change the pitch of the main blades 54. Consequently, the setpoint pressures Pc.sub.10, Pc.sub.20 of the fluids flowing respectively in each hydraulic circuit 10, 20 are determined as a function of the setpoint force Fc that the control means 4 is to supply and a function of the surface areas S.sub.43, S.sub.44. These setpoint pressures Pc.sub.10, Pc.sub.20 are thus defined by the following relationship:

F.sub.SV=Pc.sub.10.Math.S.sub.43+Pc.sub.20.Math.S.sub.44

[0111] Furthermore, the valves 31 and 32 may be integrated in the control means 4 as shown in FIGS. 2 and 3 or else they may be distinct from the control means 4, as shown in FIGS. 4 to 9.

[0112] The two hydraulic circuits 10 and 20 are independent. The hydraulic circuits 10 and 20 have their own respective fluid tanks 19, 29 respectively feeding distinct cylinders 41 and 42 of the control means 4 via different valves 31, 32. No fluid exchange takes place between the two hydraulic circuits 10, 20.

[0113] A first embodiment of a hydraulic power supply device 1 is shown in FIGS. 2 to 7. A second embodiment of the device 1 is shown in FIG. 8. A third embodiment of such a device 1 is shown in FIG. 9, which combines the first and second embodiments.

[0114] The first embodiment of a hydraulic power supply device 1 has two variants that are shown respectively in FIGS. 2 to 5 and in FIGS. 6 and 7.

[0115] Whatever the embodiment, the pressure control module 13, 23 of each hydraulic circuit 10, 20 has a first hydraulic actuator 14, 24 controlled at least in part as a function of the pressure of the fluid flowing in the hydraulic circuit 10, 20, at least one second actuator 15, 25, and calibration means 16, 26.

[0116] Within a hydraulic power supply device 1, the first actuators 14, 24 of two hydraulic circuits 10, 20 are identical, as are the second actuators 15, 25, the calibration means 16, 26, and the hydraulic pressure and flow rate generators 11, 21.

[0117] The first actuator 14, 24 has a first movable element 141, 241 on which the pressure of the fluid flowing in the hydraulic circuit 10, 20 to which the first actuator 14, 24 belongs is applied, at least in part. A first force F1 is thus generated on the first movable element 141, 241. A second force F2 generated by the calibration means 16, 26 opposes this first force F1. The calibration means 16, 26 comprise resilient means constituted by a spring working in compression.

[0118] In the first embodiment, each first actuator 14, 24 is fed solely with the fluid flowing in the hydraulic circuit 10, 20 to which the first hydraulic actuator 14, 24 belongs. The first force F1 generated by a first actuator 14, 24 thus makes it possible to characterize the pressure of the fluid flowing in the hydraulic circuit 10, 20 to which the first actuator 14, 24 belongs.

[0119] Furthermore, each pressure control module 13, 23 has a single second hydraulic actuator 15, 25 fed with the fluid flowing in one of the two hydraulic circuits 10, 20. The second actuator 15, 25 has a second movable element 152, 252 on which the pressure of this fluid feeding the second actuator 15, 25 is applied.

[0120] In a first variant of the first embodiment, the second hydraulic actuator 15, 25 is fed with the fluid flowing in the other hydraulic circuit 10, 20 to which the second actuator 15, 25 does not belong.

[0121] A first example of the first variant of this first embodiment is shown in FIGS. 2 and 3. Each hydraulic pressure and flow rate generator 11, 21 comprises a tank 19, 29 containing the fluid, a constant flow rate pump 17, 27, and pipes. These pipes are constituted firstly by feed pipes 121, 221 connecting the constant flow rate pump 17, 27 to the tank 19, 29, and secondly tank return pipes 122, 222 connecting the pressure control module 13, 23 to the tank 19, 29. The pressure control module 13, 23 of this hydraulic circuit 10, 20 then modifies the return flow rate of the tank 19, 29 of the fluid flowing in the tank return pipe 122, 222 in order to regulate the pressure of the fluid flowing in the hydraulic circuit 10, 20.

[0122] The constant flow rate pumps 17, 27 are identical and they deliver the same fluid flow rate into each hydraulic circuit 10, 20.

[0123] Each second actuator 15, 25 includes a spring 151, 251 acting on the second movable element 152, 252 and opposing the action of the fluid feeding the second actuator 15, 25. A third force F3 is then generated on each second movable element 152, 252, combining the actions of the spring 151, 251 and of the fluid feeding the second actuator 15, 25. The third force F3 serves to characterize the pressure of the fluid flowing in this other hydraulic circuit 10, 20.

[0124] The third force F3 acts on the calibration means 16, 26 that is integrated in the first actuator 14, 24 by means of an independent part 142, 242. The third force F3 thus serves to modify the calibration setting of the calibration means 16, 26 and thus modify the second force F2 applied by the calibration means 16, 26 on the first movable element 141, 241. This second force F2 is thus a function of the pressure of the fluid flowing in the other hydraulic circuit 10, 20 to which the second hydraulic actuator 15, 25 does not belong, and it opposes the first force F1.

[0125] The calibration setting corresponds to a prestress that is to be applied to the calibration means 16, 26.

[0126] The first movable element 141, 241 then acts as a valve member and enables the return flow rate of the fluid flowing in the tank return pipe 122, 222 leading to the tank 19, 29 to be modified as a function of the pressures of these fluids flowing in the two hydraulic circuits 10, 20. The first force F1 tends to cause the first movable element 141, 241 to move so as to increase this return flow rate, while the second force F2 tends to cause the first movable element 141, 241 to move so as to reduce this return flow rate.

[0127] Each pressure control module 13, 23 thus enables the pressure P.sub.10, P.sub.20 of the fluid flowing in a hydraulic circuit 10, 20 to be regulated as a function of the pressures P.sub.10 and P.sub.20 of the fluids flowing in the two hydraulic circuits 10 and 20.

[0128] When the pressures P.sub.10, P.sub.20 of the fluids flowing in the two hydraulic circuits 10, 20 are equal, as shown in FIG. 2, the first forces F3, F′3 applied to each second movable element 152, 252 are equal. Consequently, the second forces F2, F′2 generated respectively by the calibration means 16, 26 are likewise equal, as are the first forces F1, F′1 generated respectively on each first movable element 141, 241 and opposing the second forces F2, F′2.

[0129] Consequently, the movement of the first movable element 141, 241 of each hydraulic circuit 10, 20 balances the second force F2, F′2, which is equal to a calibration force of the calibration means 16, 26, with the pressure of the fluid of the hydraulic circuit 10, 20 and the first force F1, F′1. This movement of the first movable element 141, 241 is the same for each hydraulic circuit 10, 20. Consequently, the return flow rates of the fluid flowing respectively in the tank return pipes 122, 222 of the two hydraulic circuits 10, 20 are the same.

[0130] This operation of the hydraulic circuits 10, 20 with equal pressures P.sub.20, P.sub.20 for the fluids constitute nominal and balanced operation between the two hydraulic circuits 10, 20. These pressures F.sub.10, P.sub.20 of the fluid flowing in the two hydraulic circuits 10, 20 are equal to the setpoint pressures Pc.sub.10, Pc.sub.20. These setpoint pressures Pc.sub.10, Pc.sub.20 are characterized by a calibration force of each of the calibration means 16, 26.

[0131] Nevertheless, these setpoint pressures Pc.sub.10, Pc.sub.20 can be different for each hydraulic circuit 10, 20, in particular when the surface areas S.sub.43, S.sub.44 of the pistons 43, 44 arranged in the cylinders 41, 42 are different.

[0132] When one of the pressures P.sub.20, P.sub.20 decreases, e.g. the second pressure P.sub.20, as a result of a malfunction of the second hydraulic circuit 20 as shown in FIG. 3, then the third force F3 applied to the second movable element 152 of the first hydraulic circuit 10 and generated by this second pressure P.sub.20 increases. The calibration setting of the first calibration means 16 of the first hydraulic circuit 10 is then modified as a result of the increase of the third force F3 and of the second force F2, as generated by the first calibration means 16 then increases, as does the first force F1 opposing the second force F2.

[0133] Consequently, the first movable element 141 of the first hydraulic circuit 10 moves so as to reduce the return flow rate of the fluid flowing in the first hydraulic circuit 10 to the tank 19, 29 and to increase the first pressure P.sub.10 of the fluid flowing in the first hydraulic circuit 10. This modification of the third force F3 thus leads to a modification of the first setpoint pressure Pc.sub.10. The first pressure control module 13 of the first hydraulic circuit 10 thus controls the movement of the first movable element 141 and the return flow rate so that the first pressure P.sub.10 is equal to a new first setpoint pressure Pc.sub.10.

[0134] The increase in the first pressure P.sub.10 then acts on the second actuator 25 of the second hydraulic circuit 20 and reduces the third force F′3 applied on the second movable element 252 of the second hydraulic circuit 20. Consequently, the calibration setting of the second calibration means 26 of the second hydraulic circuit 20 is modified as a result of the decrease in the third force F3, and the second force F′2 as generated by the second calibration means 26 decreases, as does the first force F′1 opposing the second force F′2.

[0135] This decrease in the first force F′1 leads to a movement of the first movable element 241 of the second hydraulic circuit 20, and consequently to a modification of the second setpoint pressure Pc.sub.20. The second pressure control module 23 of the second hydraulic circuit 20 thus controls movement of the second movable element 241 and reduces the return to the tank 19, 29 so that the second pressure P.sub.20 of the fluid flowing in the second hydraulic circuit 20 becomes equal to the new second setpoint pressure Pc.sub.20.

[0136] A second example of the first variant of this first embodiment is shown in FIGS. 4 and 5. The hydraulic pressure and flow rate generator 11, 21 comprises a tank 19, 29 containing the fluid, a variable flow rate pump 17, 27 of flow rate that is automatically regulated and provided with a pressure regulator 18, 28, and pipes. These pipes are constituted firstly by feed pipes 121, 221 connecting the variable flow rate pump 17, 27 with the tank 19, 29 and secondly by tank return pipes 122, 222 connecting the pressure regulator 18, 28 with the tank 19, 29. The pressure control module 13, 23 controls the pressure regulator 18, 28 so as to adapt the flow rate of the variable flow rate pump 17, 27 and thus regulates the pressure of the fluid flowing in the hydraulic circuit 10, 20, with the tank return pipes 122, 222 enabling the fluid to return to the tank 19, 29.

[0137] Furthermore, the hydraulic pressure and flow rate generator 11, 21 of each hydraulic circuit 10, 20 includes a fluid accumulator 111, 221 constituting a reserve of hydraulic power. Each accumulator 111, 221 serves in particular to respond to a large and rapid need for hydraulic power by supplying an additional flow of fluid in the hydraulic circuit 10, 20.

[0138] The position of the first movable element 141, 241 of each first actuator 14, 24 serves to control a pressure regulator 18, 28 by modifying the flow rate of fluid feeding the pressure regulator 18, 28.

[0139] A third force F3 is generated by the action of the fluid feeding the second actuator 15, 25 on the second movable element 152, 252 of the second actuator 15, 25, and characterizes the pressure of this fluid flowing in this other hydraulic circuit 10, 20. The third force F3 acts directly on the first movable element 141, 241 of the first actuator 14, 24.

[0140] The calibration means 16, 26 apply the second force F2 directly against the first movable element 141, 241 of the first actuator 14, 24. Consequently, the second force F2 opposes the sum of the first force F1 plus the third force F3. The third force F3 thus makes it possible via the first movable element 141, 241 to modify the position of the first movable element 141, 241, and consequently to modify the calibration setting of the calibration means 16, 26. This movement of the first movable element 141, 241 then acts on the pressure regulator 18, 28.

[0141] Each pressure control module 13, 23 thus enables the pressure P.sub.10, P.sub.20 of the fluid flowing in a hydraulic circuit 10, 20 to be regulated as a function of the pressures P.sub.10, P.sub.20 of the fluids flowing in the two hydraulic circuits 10, 20.

[0142] When the pressures P.sub.10, P.sub.20 of the fluids flowing in the two hydraulic circuits 10, 20 are equal, as shown in FIG. 4, the first forces F1, F′1 applied to each first movable element 141, 241 are equal, and the third forces F3, F′3 applied to each second movable element 152, 252 are equal. Consequently, the second forces F2, F′2 generated respectively by one of the calibration means 16, 26 and opposing the sum of the first and third forces F1, F′1, F′1, F3, F′3 are likewise equal.

[0143] Consequently, the first movable element 141, 241 of each hydraulic circuit 10, 20 controls a pressure regulator 18, 28 of a hydraulic pressure and flow rate generator 11, 21 in identical manner so as to maintain the pressure P.sub.10, P.sub.20 in each hydraulic circuit 10, 20 equal respectively to the setpoint pressure Pc.sub.10, Pc.sub.20.

[0144] As in the first example, this operation of the hydraulic circuits 10, 20 with equal pressures P.sub.10, P.sub.20 for the fluids constitute nominal and balance operation between the two hydraulic circuits 10, 20.

[0145] When one of the pressures P.sub.10, P.sub.20 decreases, e.g. the second pressure P.sub.20 as a result of a malfunction of the second hydraulic circuit 20, as shown in FIG. 5, then the third force F3 applied to the second movable element 152 of the first hydraulic circuit 10 and generated by the second pressure P.sub.20 of the fluid flowing in the second hydraulic circuit 20 decreases. Consequently, the sum of the first force F1 plus the third force F3 also decreases, as does the second force F2 generated by the first calibration means 16 and opposing this sum of the first force F1 plus the third force F3. The calibration setting of the first calibration means 16 of the first hydraulic circuit 10 is then modified as a result of the decrease in the third force F3.

[0146] Consequently, the first movable element 141 of the first hydraulic circuit 10 moves to act on the pressure regulator 18 and thus increases the first setpoint pressure Pc.sub.10 so as to compensate for the drop in the second pressure P.sub.20 of the fluid flowing in the second hydraulic circuit 20. This modification to the calibration setting of the first calibration means 16 thus leads to a modification of the first setpoint pressure Pc.sub.10.

[0147] This increase in the first setpoint pressure Pc.sub.10 leads to an increase in the first pressure P.sub.10 of the fluid in the first hydraulic circuit 10, which then acts on the second actuator 25 of the second hydraulic circuit 20. The third force F′3 applied to the second movable element 252 of the second hydraulic circuit 20 increases, modifying the calibration setting of the second calibration means 26 of the second hydraulic circuit 20 so as to reduce the second setpoint pressure Pc.sub.20.

[0148] Thus, for this first variant of this first embodiment, the setpoint pressures Pc.sub.10, Pc.sub.20 are modified as a function of the variations in the pressures P.sub.10, P.sub.20 of the fluids flowing in the two hydraulic circuits 10, 20, with a variation in the pressure P.sub.10, P.sub.20 in one hydraulic circuit 10, 20 being compensated by an opposite variation in the pressure P.sub.10, P.sub.20 in the other hydraulic circuit 10, 20. As a result, the pressures P.sub.10, P.sub.20 are regulated and adapted so that the operating force F.sub.SV supplied by the control means 4 is equal to the setpoint force Fc.

[0149] The setpoint pressures Pc.sub.10, Pc.sub.20 of the fluids flowing in the two hydraulic circuits 10, 20 are defined respectively by a calibration setting of the calibration means 16, 26 of each hydraulic circuit 10, 20 so that the operating force F.sub.SV supplied by the control means 4 is equal to the setpoint force Fc. As a result, variation of a pressure in one circuit leads to a change in the calibration settings of the calibration means 16, 26 and consequently to a modification in the setpoint pressures Pc.sub.10, Pc.sub.20.

[0150] Advantageously, these new setpoint pressures Pc.sub.10, Pc.sub.20 still enable the operating force F.sub.SV supplied by the control means 4 to be equal to the fluid force Fc.

[0151] A second variant of this first embodiment is shown in FIGS. 6 and 7. The hydraulic pressure and flow rate generator 11, 21 comprises a tank 19, 29, a variable flow rate pump 17, 27 of flow rate that is automatically regulated and provided with a pressure regulator 18, 28, together with feed pipes 121, 221, and tank return pipes 122, 222.

[0152] Each second hydraulic actuator 15, 25 is fed with the fluid flowing in the hydraulic circuit 10, 20 to which the second actuator 15, 25 belongs. Each second actuator 15, 25 includes a spring 151, 251 acting on the second movable element 152, 252 so that its action is added to that of the fluid feeding the second actuator 15, 25. A third force F3 is then generated on each second movable element 152, 252 by combining the actions of the springs 151, 251 and of the fluid feeding the second actuator 15, 25. The third force F3 thus serves to characterize the pressure of the fluid flowing in the hydraulic circuit 10, 20 to which the second actuator 15, 25 belongs.

[0153] The two second actuators 15, 25 are axially in alignment and the two second movable elements 152, 252 bear against each other while being structurally distinct. As a result, the third forces F3, F′3 of the second movable elements 152, 252 are applied reciprocally against the second movable element 152, 252 of the other second actuator 15, 25. Furthermore, each second movable element 152, 252 of a second actuator 15, 25 includes pipes 153, 253 enabling the first actuator 14, 24 of the pressure control module 13, 23 to which the second actuator 15, 25 belongs to be fed at least in part with the fluid feeding the second actuator 15, 25. Nevertheless, the position of the second movable element 152, 252 in a second actuator 15, 25 modifies the fluid flow rate feeding the first actuator 14, 24.

[0154] The third forces F3, F′3 of the two second actuators 15, 25 thus serve to modify the flow rate and consequently the pressure of the fluid feeding each first actuator 14, 24. Consequently, each first actuator 14, 24 is fed at least in part with the fluid flowing in the hydraulic circuit 10, 20 to which the first hydraulic actuator 14, 24 belongs via the second actuator 15, 25, and depending on the position of the second movable element 152, 252 of the second actuator 15, 25. A first force F1 is generated by the action of the fluid feeding the first actuator 14, 24 on the first movable element of the first actuator 14, 24.

[0155] This force F1, F′1 is thus generated as a function of the pressure P.sub.10, P.sub.20 of the fluid flowing in the hydraulic circuit 10, 20 to which the first actuator 14, 24 belongs, and as a function of the third forces F3, F′3. Furthermore, the third forces F3, F′3 are defined as a function of the pressures P.sub.10, P.sub.20 of the fluids flowing in each hydraulic circuit 10, 20. As a result, the first force F1, F′1 applied by each first actuator 14, 24 is generated respectively as a function of the pressure P.sub.10, P.sub.20 of the fluid flowing in each hydraulic circuit 10, 20.

[0156] The second force F2, F′2 of the calibration means 16 of a hydraulic circuit 10, 20 opposes the first force F1, F′1 of the same hydraulic circuit 10, 20 and balances it. Consequently, the position of the first movable element 141, 241 of a first actuator 14, 24 serves to regulate the flow rate of fluid feeding the pressure regulator 18, 28.

[0157] Each pressure control module 13, 23 thus serves to regulate the pressure P.sub.10, P.sub.20 of the fluid flowing in a hydraulic circuit 10, 20 as a function of the pressures P.sub.10, P.sub.20 of the fluid flowing in the two hydraulic circuits 10, 20.

[0158] When the pressures P.sub.10, P.sub.20 of the fluids flowing in both hydraulic circuits 10, 20 are equal, as shown in FIG. 6, then the third forces F3, F′3 applied to each second movable elements 152, 252 are equal, and the second movable elements 152, 252 have a similar position in each second actuator 15, 25. Consequently, each second actuator 15, 25 feeds a first actuator 14, 24 with all of the flow of fluid flowing in the hydraulic circuit 10, 20 to which the first actuator 14, 24 belongs.

[0159] The first forces F1, F′1 generated on respective first movable elements 141, 241 are likewise equal, as are the second forces F2, F′2 generated on respective calibration means 16, 26 and opposing the respective first forces F1, F′1.

[0160] Consequently, the position of each first movable element 141, 241 is the same in each hydraulic circuit 10, 20. As a result, the fluid flow rates feeding the pressure regulators 18, 28 are the same, enabling the pressures P.sub.20, P.sub.20 of the fluids flowing in the two hydraulic circuits 10, 20 to be regulated on the basis of setpoint pressures Pc.sub.10, Pc.sub.20 that are equal.

[0161] This operation of the hydraulic circuits 10, 20 with fluid pressures P.sub.20, P.sub.20 that are equal is nominal and balanced operation between the two hydraulic circuits 10, 20. These pressures P.sub.20, P.sub.20 of the fluid flowing in the two hydraulic circuits 10, 20 are respectively equal to the setpoint pressures Pc.sub.10, Pc.sub.20 of the fluids. The setpoint pressures Pc.sub.10, Pc.sub.20 are characterized by a calibration setting of each calibration means 16, 26.

[0162] Nevertheless, these setpoint pressures Pc.sub.10, Pc.sub.20 may be different for each hydraulic circuit 10, 20, in particular when the surface areas S.sub.43, S.sub.44 of the pistons 43, 44 arranged in the cylinders 41, 42 are different.

[0163] When one of the pressures P.sub.10, P.sub.20 decreases, e.g. the second pressure P.sub.20 as a result of a malfunction of the second hydraulic circuit 20, as shown in FIG. 7, the third force F′3 applied to the second movable element 252 of the second hydraulic circuit 20 and generated by the second pressure P.sub.20 of the fluid flowing in the second hydraulic circuit 20 decreases. Consequently, the third force F3 applied to the second movable element 152 of the first hydraulic circuit 10 increases, and both second movable elements 152 and 252 move. As a result of these two second movable elements 152, 252 moving, the fluid flow rate feeding the first hydraulic actuator 241 of the second hydraulic circuit 20 remains unchanged, whereas the fluid flow rate feeding the first hydraulic actuator 141 of the first hydraulic circuit 10 is reduced.

[0164] The pressure of the fluid feeding the first actuator 241 of the second circuit 20 is thus less than the second setpoint pressure Pc.sub.20 of the second hydraulic circuit 20. The second pressure regulator 28 thus controls the second variable flow rate pump 27 so as to increase its flow rate in order to cause this second pressure P.sub.20 of the second hydraulic circuit 20 to increase and approach the second setpoint pressure Pc.sub.20. If the malfunction of the second hydraulic circuit 20 was temporary, then the second pressure P.sub.20 of the second hydraulic circuit 20 will increase and become equal once again to the initial second setpoint pressure Pc.sub.20. If the malfunction of the second hydraulic circuit 20 is permanent, then the second pressure P.sub.20 cannot increase sufficiently and will remain less than the initial second setpoint pressure Pc.sub.20 so as to stabilize on a new second setpoint pressure Pc.sub.20. This second setpoint pressure Pc.sub.20 may be zero if the malfunction of the second circuit is a major leak or a total failure of the second pump 27.

[0165] In parallel, the pressure of the fluid feeding the first actuator 141 of the first circuit 10 is then less than the first pressure P.sub.10 of the fluid flowing in the first hydraulic circuit 10. The first pressure regulator 18 thus controls the first variable flow rate pump 17 so as to increase its flow rate in order to cause the first pressure P.sub.10 to increase and compensate for the decrease in the second pressure P.sub.20. The first pressure P.sub.10 will then stabilize on a new first setpoint pressure Pc.sub.10.

[0166] Consequently, the increase in the first pressure P.sub.10 leads to an increase in the third force F3. The positions of the two second movable elements 152, 252 then stabilize so that each hydraulic circuit 10, 20 operates with a new setpoint pressure Pc.sub.10, Pc.sub.20.

[0167] Advantageously, these new setpoint pressures Pc.sub.10, Pc.sub.20 still enable the operating force F.sub.SV supplied by the control means 4 to be equal to the fluid force Fc.

[0168] In these first and second variants of the first embodiment of the hydraulic power supply device 1, the fluid force Fc is constant and preferably equal to the maximum force that the control means 4 need to be able to supply in its operating range plus a safety margin.

[0169] Furthermore, each second hydraulic actuator 15, 25 includes damping means 60 in order to stabilize the operation of the pressure control module 13, 23. The first actuator 14, 24 can also include damping means 60. The damping means 60 may comprise sealing means 61, e.g. a gasket. Such sealing means 61 constitute braking means during movements of the second movable element 152, 252, as shown in FIGS. 6 and 7. Such damping means 60 and sealing means 61 are also shown in FIGS. 3, 5, 10, and 11.

[0170] In the second embodiment of this device 1 as shown in FIG. 8, the pressure control module 13, 23 of each hydraulic circuit 10, 20 comprises a hydraulic first actuator 14, 24 fed solely by fluid flowing in the hydraulic circuit 10, 20, calibration means 16, 26, an electric second actuator 15, 25, and control means 155, 255. Each control means 155, 255 supplies an electric signal controlling the operation of a second actuator 15, 25.

[0171] The first force F1, F′1 generated by a first actuator 14, 24 thus serves to characterize the pressure of the fluid flowing in the hydraulic circuit 10, 20 to which the first actuator 14, 24 belongs.

[0172] The second actuator 15, 25 is controlled to move by an electric signal supplied by the control means 155, 255. The movement of a second actuator 15, 25 acts on the calibration means 16, 26 and modifies its calibration setting.

[0173] Consequently, for the same first force F1, F′1 generated by the pressure of the fluid applied to the first movable element 141, 241, the position of the first movable element 141, 241 is modified as a result of a change in the calibration setting of the calibration means 16, 26.

[0174] Consequently, the action of the first actuator 14, 24 on a pressure regulator 18, 28 is also modified, thereby having the effect of modifying the setpoint pressure Pc.sub.20, Pc.sub.20 of the hydraulic circuit 10, 20.

[0175] The second actuator 15, 25 of one hydraulic circuit 10, 20 may be controlled by the pressure of the fluid flowing in the other hydraulic circuit 10, 20 of the device 1. Under such circumstances, each hydraulic circuit 10, 20 has a pressure sensor 156, 256 connected to respective control means 155, 255. Thus, a variation in the first pressure P.sub.10 of a first hydraulic circuit 10 leads to action of the second actuator 25 of the second circuit 20 modifying the second setpoint pressure Pc.sub.20 of the second hydraulic circuit 20 so as to compensate for the variation in the first pressure P.sub.10. In parallel, since the second pressure P.sub.20 is modified as a result of the modification to the second setpoint pressure Pc.sub.20, the second actuator 15 of the first hydraulic circuit 10 modifies the first setpoint pressure Pc.sub.10.

[0176] The two hydraulic circuits 10, 20 then stabilize as soon as the pressure P.sub.10, P.sub.20 of each hydraulic circuit 10, 20 is equal to the respective new setpoint pressure Pc.sub.10, Pc.sub.20.

[0177] Advantageously, these new setpoint pressures Pc.sub.10, Pc.sub.20 still enable the operating force F.sub.SV supplied by the control means 4 to be equal to the fluid force Fc, which is constant and preferably equal to a maximum force that the control means 4 needs to be able to supply in its operating range, plus a safety margin.

[0178] The second actuator 15, 25 of a hydraulic circuit 10, 20 may also be controlled by one or more parameters external to the hydraulic circuit 10, circuits 10, 20.

[0179] Each control means 155, 255 is connected to a computer 5 of the aircraft 50. The computer 5 receives information about the type of mission being undertaken by the aircraft 50, about the region of its flight envelope in which the aircraft 50 is operating, or indeed about the actions performed by the pilot on each flight control of the aircraft 50. The computer 5 can then define the setpoint force Fc that is necessary and sufficient for controlling changes to the pitch of the main blades 54. Finally, the computer 5 can supply a signal to each of the control means 155, 255 corresponding to new setpoint pressures Pc.sub.10, Pc.sub.20 that correspond to this setpoint force Fc. Each of the control means 155, 255 then supplies a second actuator 15, 25 with a movement order so as to modify each of the setpoint pressures Pc.sub.10, Pc.sub.20.

[0180] Advantageously, the fluid force Fc is then variable and equal to a current force that the control means 4 needs to be capable of supplying, plus a safety margin. Consequently, the setpoint pressures Pc.sub.10, Pc.sub.20 are also variable and they adapt to the current requirements of the aircraft 50. Consequently, the pressure of each hydraulic circuit 10, 20 is regulated so that the control means 4 provide hydraulic power that is just sufficient for the needs of the aircraft 50, thereby optimizing its energy consumption.

[0181] Each of the control means 155, 255 is also connected to action means 7, such as a switch, that the pilot can actuate when the pilot desires to benefit from additional hydraulic power from the control means 4. Thus, when the pilot actuates the action means 7, each of the control means 155, 255 supplies a second actuator 15, 25 with a movement order so as to increase each of the setpoint pressures Pc.sub.10, Pc.sub.20. The fluid force Fc is increased, and the pilot has greater hydraulic power available for changing the pitch of the main blades 54, e.g. in anticipation of a drop of fluid pressure in a hydraulic circuit 10, 20 during landing under difficult conditions, or indeed during a winching operation.

[0182] The third embodiment of the hydraulic power supply device 1 shown in FIG. 9 combines the first and second embodiments. The pressure control module 13, 23 of each hydraulic circuit 10, 20 comprises a first actuator 14, 24 that is hydraulic, calibration means 16, 26, a first second actuator 15, 25 that is hydraulic, a second second actuator 15′, 25′ that is electric, and control means 155, 255.

[0183] The first hydraulic actuator 14, 24, the hydraulic first second actuator 15, 25, and the calibration means 16, 26 are identical to those of the second example of the first variant of the first embodiment of the invention as shown in FIGS. 4 and 5.

[0184] The electric second second actuator 15′, 25′ is identical to the second actuator of the second embodiment shown in FIG. 8. Each control means 155, 255 supplies an electric signal controlling the operation of a second second actuator 15′, 25′.

[0185] Thus, each first second actuator 15, 25 enables the setpoint pressure Pc.sub.10, Pc.sub.20 of a first hydraulic circuit 10, 20 to be adapted as a function of the pressure of the fluid flowing in the second hydraulic circuit 10, 20 as in the second example of the first variant of the first embodiment. The fluid force Fc is constant.

[0186] Furthermore, each second second actuator 15′, 25′ enables the setpoint pressure Pc.sub.10, Pc.sub.20 of a hydraulic circuit 10, 20 to be adapted as a function of one or more parameters external to the hydraulic circuits 10, 20, such as the type of mission being undertaken by the aircraft 50, the region of its flight envelope in which the aircraft 50 is operating, or indeed an action carried out by the pilot on a flight control of the aircraft 50, as for the second embodiment.

[0187] This third embodiment serves advantageously to dissociate firstly a first second actuator 15, 25 that is hydraulic for modifying the setpoint pressure Pc.sub.10, Pc.sub.20 of each hydraulic circuit 10, 20 depending on the operation of each hydraulic circuit 10, 20 so as to enable the control means 4 to supply a fluid force Fc that is constant, from secondly a second second actuator 15′, 25′ that is electric for modifying the setpoint pressures Pc.sub.10, Pc.sub.20 of each hydraulic circuit 10, 20 depending on one or more parameters, enabling the control means 4 to supply a fluid force Fc that is variable and adapted to the current situation of the aircraft 50.

[0188] Furthermore, a hydraulic receiver 3 can be fed by a single hydraulic circuit 10 as shown in FIGS. 10 and 11. The hydraulic circuit 10 comprises a generator 11 of hydraulic pressure and flow rate in a fluid, pipes 12, and a pressure control module 13. The pipes 12 connect the hydraulic pressure and flow rate generator 11 with the hydraulic receiver 3, and they feed it with fluid under pressure.

[0189] The hydraulic receiver 3 includes control means 4 and a valve 31 controlling the feed of fluid from the control means 4 as a function of a control order. By way of example, this control order comes from a flight control present in the aircraft 50 and operated by a pilot in order to modify the pitch of the main blades 54 of the main rotor 52.

[0190] The control means 4 can cause the pitch of the main blades 54 to be modified by applying an operating force F.sub.SV via the rod 45. This operating force F.sub.SV is equal to a setpoint force Fc so as to guarantee that this operating force F.sub.SV is greater than or equal to the force needed for modifying the pitch of the main blades 54. Consequently, a setpoint pressure Pc.sub.10 of the fluid flowing in the hydraulic circuit 10 is determined as a function of the setpoint force Fc that the control means 4 need to supply and of the surface area S.sub.43 of the piston 43 arranged in the control means 4.

[0191] As in each hydraulic circuit 10, 20 shown in FIGS. 6 to 9, the hydraulic pressure and flow rate generator 11 comprises a tank 19 containing the fluid, a variable flow rate pump 17 of flow rate that is automatically regulated, and provided with a pressure regulator 18, together with feed pipes 121, and tank return pipes 122. The pressure control module 13 controls the pressure regulator 18 so as to adapt the flow rate of the variable flow rate pump 17 and thus regulate the pressure P.sub.10 of the fluid flowing in the hydraulic circuit 10 depending on the initial setpoint pressure Pc.sub.10.

[0192] The pressure control module 13 of the hydraulic circuit 10 comprises a first actuator 14 that is hydraulic and controlled by the pressure of the fluid flowing in the hydraulic circuit 10, a second actuator 15 that is electric and that is controlled by control means 155, and calibration means 16.

[0193] The hydraulic first actuator 14 has a first movable element 141 on which the pressure of the fluid flowing in the hydraulic circuit 10 is applied. A first force F1 is thus generated on this first movable element 141. A second force F2 generated by the calibration means 16 opposes this first force F1. The calibration means 16 comprises resilient means constituted by a spring working in compression.

[0194] The control means 155 is connected to action means 7, such as a switch actuatable by the pilot when the pilot desires to benefit from additional hydraulic power from the control means 4. The second actuator 15 comprises a ferromagnetic element 154 secured to the first movable element 141. When the second actuator 15 is electrically powered, it delivers a magnetic field causing a third force F3 to appear on the ferromagnetic element 154 so as to move the first movable element 141.

[0195] Thus, when the pilot does not actuate the action means 7, the third force F3 is zero, as shown in FIG. 10. Consequently, only the first and second forces F1, F2 are applied to the first movable element 141. As a result, the pressure regulator 18 acts to regulate the pressure P.sub.10 of the fluid flowing in the hydraulic circuit 10 on the initial setpoint pressure Pc.sub.10, this initial setpoint pressure Pc.sub.10 being a function of the calibration setting of the calibration means 16.

[0196] Thereafter, when the pilot actuates the action means 7, as shown in FIG. 11, the control means 155 electrically powers the second actuator 15 so as to generate the magnetic field and moves the first movable element 141. This movement of the first movable element 141 causes the setpoint pressure Pc.sub.10 to increase. The fluid force Fc is also increased and the pilot has greater hydraulic power available for changing the pitch of the main blades 54, thus anticipating a maneuver with high power requirements. When the pressure P.sub.10 of the fluid flowing in the hydraulic circuit 10 increases so as to come close to the new setpoint pressure Pc.sub.10, the first force F1 increases and the movable element 141 moves so that the pressure regulator 18 stabilizes the pressure of the fluid flowing in the hydraulic circuit 10 to a level of this new setpoint pressure Pc.sub.10.

[0197] Finally, when the pilot deactivates the second actuator 15 by acting once more on the action means 7, the first movable element 141 is no longer subjected to the third force F3 and is moved only under the effect of the pressure of the fluid flowing in the first circuit 10, which generates the first force F1, and the second force F2 as generated by the calibration means 16. The setpoint pressure Pc.sub.10 is modified and returns to its initial value. The pressure P.sub.10 of the fluid flowing in the first circuit 10 decreases until it stabilizes on the initial setpoint pressure Pc.sub.10. The fluid force Fc is also modified to return to its initial value.

[0198] The second actuator 15 then supplies a force F3 which is either zero when the second actuator 15 is deactivated, or else equal to a predefined value when the second actuator 15 is activated. Consequently, the setpoint force Fc is variable, but can only take on two different values: a first fluid force Fc1 corresponding to nominal operation of the aircraft, and a second fluid force Fc2 corresponding to operation with “temporary extra power” for enabling the pilot of the aircraft 50 to act safely when performing maneuvers having greater power requirements, such as hovering or landing on a platform under difficult weather conditions, for example.

[0199] It should be observed that whatever the embodiment of the hydraulic power supply device 1 provided with two hydraulic circuits 10, 20, the two hydraulic circuits 10, 20 may be identical or they may be different. Likewise, the cylinders 41, 42 of multi-cylinder control means 4 may be identical or indeed different.

[0200] Naturally, the present invention may be subjected to numerous variations as to its implementation. Although several embodiments are described, it will readily be understood that it is not conceivable to identify exhaustively all possible embodiments. It is naturally possible to envisage replacing any of the means described by equivalent means without going beyond the ambit of the present invention.