Adaptively-twistable blade, and an aircraft including such a blade

Abstract

A blade (1) having an outer covering (2) defining a cavity (8). A carriage (20) is arranged in said cavity (8), the carriage (20) being provided with a torsion bar (21) and at least two arms (22) secured to the torsion bar (21). The blade has one connection per arm provided both with an upstream guide gallery and with a downstream guide gallery, each arm extending transversely from an upstream end that slides in an upstream guide gallery to a downstream end that slides in a downstream guide gallery. At least one connection is a helical connection (40) obtained with the help of an upstream guide gallery (33) and the downstream guide gallery (34) of the segment (101) presenting distinct orientations, giving rise to movement in rotation (ROT1) of the segment (101) under the effect of the carriage (20) moving in translation.

Claims

1. An adaptively-twistable rotor blade provided with a lift element having an outer covering extending spanwise in a longitudinal direction from a first end zone to a second end zone, and transversely from a leading edge to a trailing edge, the outer covering defining an internal cavity, wherein said blade includes at least one adaptive twister system provided with: a carriage arranged in said cavity, said carriage having a torsion bar extending along said longitudinal direction and at least two arms that are secured to the torsion bar and that extend transversely on either side of the torsion bar, said carriage being movable in translation in said cavity along said longitudinal direction; a connection on each arm for connecting said carriage to the outer covering, each connection including a segment including an upstream guide gallery arranged in the cavity between the leading edge of the blade and the torsion bar and a downstream guide gallery arranged in the cavity between the trailing edge of the blade and the torsion bar, each arm extending transversely from an upstream end that slides in an upstream guide gallery to a downstream end that slides in a downstream guide gallery; and at least one of said connections being a helical connection such that the segment associated therewith is a twister segment and the upstream guide gallery and the downstream guide gallery for the twister segment present distinct orientations, and impart movement in rotation to the twister segment under the effect of the carriage moving in translation.

2. A blade according to claim 1, wherein said torsion bar extends along a geometrical twist line of the blade.

3. A blade according to claim 1, wherein at least one arm of the at least two arms extends symmetrically on either side of the torsion bar and is perpendicular to the torsion bar.

4. A blade according to claim 1, wherein, for at least one of the segments, the upstream guide gallery associated therewith is arranged against the leading edge of the blade and the downstream guide gallery associated therewith is arranged against the trailing edge of the blade.

5. A blade according to claim 1, wherein at least one of the upstream and downstream guide galleries associated with the helical connection and the twister segment includes a plurality of inclined planes.

6. A blade according to claim 1, wherein at least one of the upstream and downstream guide galleries associated with the helical connection the twister segment includes a curved slope.

7. A blade according to claim 1, wherein at least one end of an arm of the at least two arms includes running means facilitating sliding of the arm in a corresponding guide gallery.

8. A blade according to claim 1, wherein said carriage includes the at least two arms co-operating with guide galleries by moving in rotation in opposite directions.

9. A blade according to claim 1, wherein each of said segments comprises a frame defining the upstream and downstream guide galleries associated therewith together with an orifice allowing the carriage to move in translation through the segment, said frame being covered by said outer covering.

10. A blade according to claim 1, wherein said carriage includes at least three arms.

11. A blade according to claim 1, wherein said blade includes at least two adaptive twister systems.

12. A blade according to claim 1, wherein said adaptive twister system includes an actuator connected to said carriage for moving said carriage in translation in at least one direction, said actuator being arranged in said cavity.

13. A blade according to claim 12, wherein said actuator comprises a motor and a wormscrew co-operating with a nut.

14. A blade according to claim 12, wherein said adaptive twister system includes a force-amplifying mechanical advantage device interposed between the actuator and the carriage.

15. A blade according to claim 14, wherein said mechanical advantage device comprises a hydraulic member having a main piston of large area in hydraulic communication with a plurality of intermediate pistons of small area, the main piston being constrained to move in translation with said carriage, each intermediate system being controlled by an actuator.

16. A blade according to claim 14, wherein said mechanical advantage device comprises an elongate tie connected to the carriage and to an actuator, the tie forming a loop around at least two pulleys.

17. A blade according to claim 14, wherein said mechanical advantage device comprises a cam connected to an actuator and to the carriage.

18. A blade according to claim 1, wherein the blade includes an actuator located outside the lift element and connected to the carriage by a tie.

19. A blade according to claim 1, wherein said carriage includes a device of variable mass in order to vary a centrifugal force exerted on the carriage.

20. A blade according to claim 1, wherein at least one arm of the at least two arms includes means for setting its length.

21. An aircraft having a rotor, wherein said rotor includes at least one blade according to claim 1.

22. An aircraft according to claim 21, wherein said aircraft includes a system for setting the speed of rotation of the rotor in order to set the centrifugal force applied to each carriage.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail from the following description of embodiments given by way of illustration with reference to the accompanying figures, in which:

(2) FIGS. 1 and 2 are views of an aircraft having a blade shown diagrammatically for explaining the operation of the invention;

(3) FIG. 3 is a plan view showing a carriage sliding in guide galleries;

(4) FIGS. 4-5 and 6-7 are sections in side view showing a carriage sliding respectively in upstream and downstream guide galleries;

(5) FIG. 8 is an exploded view of the system showing in particular a frame of a twister segment of the blade;

(6) FIGS. 9 to 13 show various embodiments of an actuator co-operating with a carriage;

(7) FIGS. 14 to 15 show various versions of guide galleries;

(8) FIG. 16 is a view of a carriage having at least three arms;

(9) FIG. 17 is a diagram showing an arm of variable length; and

(10) FIG. 18 is a view of a blade shown diagrammatically with two adaptive twister systems.

DETAILED DESCRIPTION OF THE INVENTION

(11) Elements that are shown in more than one of the figures are given the same references in each of them.

(12) It should be observed that three mutually orthogonal directions X, Y, and Z are shown in some of the figures.

(13) The first direction X is said to be longitudinal. The term “longitudinal” relates to any direction parallel to the first direction X.

(14) The second direction Y is said to be transverse. The term “transverse” relates to any direction parallel to the second direction Y.

(15) Finally, the third direction Z is said to be in elevation. The expression “in elevation” relates to any direction parallel to the third direction Z.

(16) FIG. 1 is a diagrammatic view of an aircraft 5. This aircraft 5 includes a rotor 6 having a plurality of blades. In order to avoid pointlessly overcrowding FIG. 1, only one blade 1 of the invention is shown.

(17) The blade 1 includes a lift element 9. The lift element 9 extends along a longitudinal direction X from a first end zone 3 secured to a root 9′ that is movable relative to a hub 7 of the rotor 6, towards a second end zone 4. The lift element 9 also extends in an elevation direction from a pressure side towards a suction side, and in a transverse direction from a leading edge BA towards a trailing edge BF.

(18) The lift element has an outer covering 2 defining the pressure side and the suction side. This outer covering 2 thus has a suction side skin 2′ and a pressure side skin 2″ that together define a cavity 8 inside the outer covering 2.

(19) The inside volume of the outer covering 2 is thus hollow, at least in part.

(20) The blade 1 is also provided with at least one twister system 10 for twisting the blade between two segments 101 and 102 of the blade 1 by exerting torque on the outer covering 2 over these two segments 101 and 102.

(21) The twister system 10 is provided with a carriage 20 that is arranged inside the cavity 8 of the outer covering 2. The carriage is provided in particular with a torsion bar 21 extending along the longitudinal direction X, e.g. along a geometrical twist line AX of the blade 1. The carriage can also be named “slider” or “chariot” in French language.

(22) The carriage is connected to the outer covering 2 by at least two connections including at least one helical connection 40. One such helical connection connects the carriage to one of the segments 101 of the blade 1 that is referred to as the “twister segment”.

(23) The carriage can thus be connected to the outer covering 2 by at least two helical connections, or via at least one helical connection 40 and a slideway connection 40′ in the example of FIG. 1.

(24) Under such circumstances, the carriage is movable in translation along first and second opposite directions S1 and S2 within the cavity 8. The carriage may be moved in translation under the effect of the centrifugal force FC that is applied to the carriage during rotation of the blade 1. As centrifugal force increases, the carriage moves in the first direction S1 away from the hub 7. Conversely, as centrifugal force decreases (such that it is opposed by the resilient return of the blade) the carriage moves in the second direction S2 towards the hub 7.

(25) For this purpose, the aircraft 5 may have a system for setting the speed of rotation of the rotor 6 in order to set/adjust the centrifugal force FC applied to each carriage 20.

(26) The carriage may also present mass that is adjustable in order to adjust the value of the centrifugal force that is applied to the carriage. Thus, the position of the carriage varies as a function of its mass at each instant, where this mass is adjustable.

(27) In addition or as an alternative, the carriage may move in the cavity 8 in at least one of the directions S1, S2 under drive from an actuator. For example, the actuator may move the carriage in both directions S1 and S2. In another alternative, the actuator comprises return means serving to move the carriage in the second direction S2 only, with the carriage being moved in the first direction S1 under the effect of centrifugal force.

(28) Such an actuator may be an electromechanical actuator.

(29) The actuator may also present mass that is adjustable in order to adjust the value of the centrifugal force applied to the actuator. Thus, the positions of the actuator in the blade and consequently of the carriage vary as a function of the mass of the actuator at each instant, where this mass is adjustable.

(30) With reference to FIG. 2, an actuator 60 may comprise a motor 63 for driving rotation of a wormscrew 61, the wormscrew 61 causing a nut 62 that is secured to the carriage 20 to move in translation.

(31) Movement in translation of the carriage 20 imparts movement in rotation ROT1 to each twister segment via a helical connection. This movement in rotation ROT1 causes torque to be created that twists the outer covering 2 between the two segments 101 and 102.

(32) With reference to FIG. 3, the carriage has at least two arms 22 that are secured to the torsion bar 21. At least one arm extends transversely, and possibly symmetrically, on either side of the torsion bar 21.

(33) At least one arm 22 may also extend perpendicularly to the torsion bar so as to form a T-shaped structure. A carriage with two arms 22 may thus be H-shaped.

(34) With reference to FIG. 16, the carriage may nevertheless include at least three arms.

(35) In accordance with the teaching of FIG. 3, each arm 22 may extend from an upstream end 23 towards a second end 24 that is downstream. Each end may carry running means 25. Such running means may comprise at least one wheel, at least one ball-bearing or roller-bearing, or at least one smooth bearing, for example.

(36) Under such circumstances, each connection of the carriage 20 to the outer covering 2 includes for each arm:

(37) an upstream guide gallery 31, 33 arranged in the cavity 8 between the leading edge BA of the blade 1 and the torsion bar 21; and

(38) a downstream guide gallery 32, 34 arranged in the cavity 8 between the trailing edge BF of the blade 1 and the torsion bar 21.

(39) The upstream end 23 of each arm thus slides in an upstream guide gallery 31, 33, and the downstream end 34 of each arm slides in a downstream guide gallery 32, 34.

(40) At least one segment includes an upstream guide gallery 31, 33 arranged against the leading edge BA of the blade 1 and a downstream guide gallery 32, 34 arranged against the trailing edge BF of the blade 1 in order to maximize the length of the corresponding arm 22.

(41) FIGS. 4 and 5 show respectively the upstream guide galleries 31 and 33 and downstream guide galleries 32, 34 at two distinct segments of the blade.

(42) As can be seen in FIGS. 4 and 5, the twister system 10 is provided with a helical connection 40 and with a slideway connection 40′.

(43) Under such circumstances, the upstream and downstream guide galleries 31 and 32 of the slideway connection 40′ are plane and parallel to each other.

(44) Conversely, the upstream and downstream guide galleries 33 and 34 of the helical connection 40 present different orientations and they are therefore not parallel to each other.

(45) Moving an arm in translation in these upstream and downstream guide galleries 33 and 34 of the helical connection 40 generates torsion in the torsion bar 21, and movement in rotation of the blade segment connected to these upstream and downstream guide galleries 33 and 34 of the helical connection 40. This results in torsion of the outer covering 2 between the helical connection 40 and the slideway connection 40′.

(46) In FIGS. 6 and 7, the twister system may comprise two helical connections 40 that present pitches that are different, or indeed opposite.

(47) When the pitches are opposite, as shown in FIGS. 6 and 7, the carriage 20 has two arms 22 that move in rotation in opposite directions ROT1 and ROT2 as they move in translation along the guide galleries.

(48) With reference to FIG. 14, at least one guide gallery 32, 34 of a helical connection comprises a plurality of inclined planes 35, 36.

(49) In FIG. 15, at least one guide gallery 32, 34 of a helical connection presents a curved slope 37.

(50) FIG. 8 shows a portion of a lift element extending between two segments 101, 102 fitted with guide galleries co-operating with a carriage 20. The term “segment” is used herein to designate a part of the blade extending in the span direction and fitted with upstream and downstream guide galleries. The term “portion” is used to designate a part of the blade extending in the span direction from one segment to another segment.

(51) The segments 101, 102 may comprise respective rigid frames 50 that are shown in particular in the detail views Z1 and Z2 of FIG. 8. Such a frame is a rigid frame secured to the outer covering 2.

(52) Under such circumstances, each frame presents an upstream guide gallery 33 and a downstream guide gallery 34 together with an orifice 51 enabling the carriage 20 to move in translation through the frame.

(53) Consequently, when the carriage moves in translation, the arms of the carriage slide in the guide galleries. At twister segments provided with guide galleries that are not mutually parallel, an arm also moves in rotation. This movement in rotation thus gives rise to movement in translation of the frame in which the arm is sliding, and consequently to twisting of the blade.

(54) Furthermore, the twister system may include an electromechanical actuator or a mass that is variable, e.g. for causing the carriage to move in at least one direction.

(55) Such an actuator 60 may be arranged outside the lift element of a blade, as shown in the embodiment of FIG. 9.

(56) For example, the actuator 60 may be connected to at least one carriage 20 by a filamentary tie 81. The actuator 60 may then be a jack arranged in the mast 82 that drives rotation of the hub 7 of the rotor 6.

(57) The actuator may possibly control all of the carriages of all of the blades of the rotor 6 simultaneously in order to make the twisting of the blades uniform.

(58) An actuator may also be arranged in the cavity 8 of a blade. In order to optimize the characteristics of such an actuator and make it as compact as possible, the twister system may then include a force-amplifying mechanical advantage device interposed between the carriage and the actuator.

(59) FIGS. 10 to 13 show various mechanical advantage devices 70.

(60) FIGS. 10 and 11 disclose a first mechanical advantage device.

(61) This mechanical advantage device 70 includes an elongate tie 75 connected to the carriage 20 and to an actuator 60. The mechanical advantage device 70 also includes at least pulleys 76, the tie 75 being looped around the two pulleys 76.

(62) The carriage and the actuator can then be arranged one above the other.

(63) Although FIGS. 10 and 11 show an electromechanical actuator, other types of actuator can be envisaged.

(64) FIG. 12 discloses a second mechanical advantage device 70 that is of hydraulic type.

(65) The mechanical advantage device 70 includes a casing 71 defining a hydraulic chamber 71 that is filled with an incompressible fluid 72.

(66) The mechanical advantage device 70 also includes a main piston 73 and at least two intermediate pistons sliding in the casing and in contact with the incompressible fluid. Each intermediate piston possesses a small area, i.e. a small area of contact with the incompressible fluid. Conversely, the main system possesses a large area, i.e. a large area of contact with the incompressible fluid, which area is greater than said small area.

(67) Each intermediate piston is then caused to move by an actuator, which actuator may control all of the intermediate pistons, for example.

(68) FIG. 13 shows a third mechanical advantage device 70 using a cam.

(69) Thus, the mechanical advantage device 70 may comprise a pinion 78 that is rotated by an actuator. The pinion then meshes with a rack connected to a carriage 20.

(70) FIG. 17 shows an arm having means for setting its length 100. This length 100 is the distance between the ends of the arm sliding in the guide galleries.

(71) For example, the arm comprises a fixed-length portion 22′ and two movable portions 22″ each carrying respective running means 25. The length 100 of the arm is thus variable.

(72) By way of example, the arm may include conventional hydraulic, pneumatic, or electrical means for moving the movable portions relative to the fixed-length portion.

(73) 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.

(74) For example, the blades shown have only one twister system. Nevertheless, a blade could have a plurality of portions, each provided with a respective twister system. For example, as shown in FIG. 18, the blade 1 may include at least two adaptive twister systems 10. A blade may have a plurality of such twister systems 10 along its span in order to adapt its twisting more accurately.

(75) Likewise, the figures show rectilinear arms extending perpendicularly to a torsion bar. Nevertheless, each arm may for example be V-shaped, with the ends of the arm nevertheless lying on a geometrical line extending perpendicularly to the torsion bar.