BUCKET WITH ONE FOOT WITH INTEGRATED PITCH CLIP AND TWO INTEGRATED DAMPER MOUNTS AND ROTOR WITH SUCH A BLADE

Description

[0001] The present invention relates to a blade having a root comprising an integrated pitch attachment and two integrated damper attachments and a rotor having such a blade. For example, the motor may be a main motor of a helicopter

[0002] A rotorcraft is equipped with at least one rotor, and in particular at least one rotor which contributes to the lift, or even the propulsion, of this rotorcraft.

[0003] A rotorcraft may include a rotor that participates in controlling the yaw movement of the rotorcraft. Such a rotor is sometimes arranged at the rear of a rotorcraft, for example on or in a rudder, and is then called a "tail rotor".

[0004] A rotor is usually provided with a head on which at least one blade is arranged.

[0005] A blade may be rotatable relative to the head about a pitch axis. In this case, the rotor may include a pitch rod to adjust the pitch of the blade.

[0006] Furthermore, a blade may be rotatable relative to the head around a drag axis. Therefore, the rotor may include a member usually referred to as a "drag damper" or even a "frequency adapter" or even a "drag elastic return member with incorporated damping". This drag damper may provide stiffness to allow the blade to return to an average position in the absence of alternating forces acting around the drag axis. This drag damper may dampen the movement of the blade around the drag axis, a source of vibrations.

[0007] A blade can further be movable in rotation relative to the head around a flapping axis.

[0008] A blade can then be connected to a rotor head in multiple ways.

[0009] In particular, a blade can be articulated to a rotor head by a member called a “laminated spherical stop” and a connector interposed between the blade and the spherical stop.

[0010] Document FR 2427251 A describes a rotor head comprising one opening per blade. Each opening houses a laminated spherical stop allowing rotations of the blade around a flapping axis, a pitch axis and a concurrent drag axis. The laminated spherical stop comprises a first frame, a laminated central part and a second frame fixed to the rotor head. The root of the blade is then secured to a connector, this connector comprising two branches arranged vertically on either side of the first frame of the laminated stop. Two bolts then pass through the branches of the connector, the first frame and a pitch lever. In addition, an elastic drag return strut is coupled to a fitting attached to the blade and to the rotor head.

[0011] Such an architecture is interesting. This architecture can facilitate the arrangement of at least one drag damper and the pitch rod, by moving the blade away from the rotor head. However, this arrangement requires the use of an intermediate connector with a weakly aerodynamic shape. In addition, this connector can be relatively bulky, massive and moves the blade away from the flapping, drag and pitch axes. In addition, the pitch rod is then articulated to the connector. Finally, this architecture imposes multiple components, and therefore can complicate the rotor production process.

[0012] Document FR 2671050 A1 also describes a rotor equipped with a rotor head and, for each blade, a laminated spherical stop connected by a connector to a blade root, this connector being articulated to a pitch lever and to an elastic drag return member.

[0013] Document FR 2584996 A1 describes a rotor head of this type connecting the blade to the laminated spherical stop using a sleeve in order to make the blades foldable, the sleeve carrying the pitch lever.

[0014] Document FR 2584996 A1 describes another rotor head comprising one opening per blade. Each opening houses a laminated spherical stop. The laminated spherical stop comprises a first frame, a laminated central part and a second frame fixed to the rotor head. The root of each blade is shaped as a forked attachment part with two branches fixed by a bolt to the first frame of the laminated stop. A drag damper is articulated to the rotor head and to an attachment yoke projecting from the root of the blade, on the side of the trailing edge of the blade. This yoke is carried by a spacer engaged between the branches of the forked attachment part, the spacer being fixed by two bolt and nut assemblies. On the side of the leading edge of the blade, a pitch control lever extends the spacer and ends in a yoke in which a pitch control rod is articulated.

[0015] This architecture is interesting. However, this arrangement requires multiple components, including a spacer, which can complicate the rotor production process. In addition, the fork shape is not optimized from an aerodynamic point of view.

[0016] Document FR 2529860 A1 describes a rotor head comprising two plates. For each blade, a laminated spherical stop comprises a first frame and a second frame fixed to the plates by a metal pin. This document also refers to French patent application FR 2516891 filed on November 25, 1981, which indicates that the blade comprises rovings forming a rigid loop which fits into a groove in the first frame of the laminated spherical stop. For each blade, the rotor comprises a pitch control lever fixed to the blade by bolts, and articulated both to a pitch control rod and to an elastic drag return member with incorporated damping.

[0017] Patent FR 2 898 581 B1 and document US 2007 / 280828 A1 describe a blade having lower and upper ribbons attached to a support fixed to a frame of a laminated spherical stop, this frame being articulated to a pitch rod.

[0018] Document FR 2 653 405 A1 describes a blade having a foot connected to a hub via a sleeve.

[0019] Document FR 3 053 312 A1 describes a blade attached to a fitting comprising two plates.

[0020] Document EP 2 540 620 B1 describes a blade attached to a fitting, the fitting being connected to a sleeve.

[0021] The previously cited prior documents therefore propose rotors equipped with multiple parts likely to complicate the manufacture of the rotor and / or to generate aerodynamic drag, such as blade connectors, fittings for connection to a blade lever and / or to an elastic drag return member, connectors or others.

[0022] Documents US 2014 / 212293 A1 and EP 3 246 250 B1 are also known.

[0023] The present invention therefore aims to propose an innovative blade aimed in particular at optimizing the production process and / or optimizing the mass of the rotor or its aerodynamic drag.

[0024] Thus, the invention relates to a blade comprising a blade root extended by an aerodynamic running part which extends to a free end. The blade root is configured to be connected to a rotor head. The blade is configured to be movable in rotation relative to the rotor head in use at least around a pitch axis.

[0025] In addition, the blade root comprises a single-piece composite material attachment body, the attachment body being hollow and having an envelope delimiting an empty internal space, said envelope being able to surround the pitch axis around which the blade is rotatable, the attachment body integrating a pitch attachment configured to be traversed by a pitch connecting rod connected to a pitch lever, the attachment body integrating a leading edge attachment configured to be traversed by a leading edge connecting rod connected to a first drag damper, the attachment body integrating a trailing edge attachment configured to be traversed by a trailing edge connecting rod configured to be connected to a second drag damper, the attachment body integrating a connection attachment configured to be traversed by at least two connection rods connected to a first frame of a laminated spherical stop.

[0026] The term "leading edge attachment" means that this attachment is located on the side of the blade including the leading edge of the blade. Conversely, the term "trailing edge attachment" means that this attachment is located on the side of the blade including the trailing edge of the blade.

[0027] The term "fastener" designates one or more parts of the body, and for example an orifice capable of being crossed by a rod and / or a wing of a yoke.

[0028] The term "monobloc" means that the attachment body is made of a single piece, the elements of the attachment body being inseparable from each other without breakage. A monobloc attachment body is therefore not comparable to a device comprising several members fixed to each other with reversible means, such as screws for example.

[0029] The blade thus has a single-piece blade root made of composite materials.

[0030] Furthermore, the running part of the blade and the root also constitute a single piece. The attachment body is connected to the running part, ensuring an aerodynamic transition.

[0031] The composite blade root is provided with a leading edge attachment and a trailing edge attachment for connection to conventional drag dampers, a pitch attachment for connection to a pitch rod, and a connecting attachment for articulation to a rotor head via a laminated spherical stop.

[0032] Such a composite blade root incorporating connections to the pitch rod, drag dampers and rotor head can then be dimensioned through the blade's "composite lug".

[0033] The implementation of a new type of blade integrating connections to the pitch rod, drag dampers and rotor head makes it possible to limit the number of rotor parts. This can result in a gain in terms of mass or even efforts required by operators during maintenance and / or rotor assembly. The manufacture of the blade integrating this blade root equipped with the attachment body can in particular be automated, which can tend to reduce manufacturing costs.

[0034] In addition, the blade can be stretched to improve the rotor life. In particular, the attachment body can have high fatigue resistance.

[0035] Furthermore, the attachment body forms a hollow shell which may tend to generate less aerodynamic drag than a usual connector or a forked part.

[0036] In another aspect, directly connecting the blade to a laminated spherical stop, i.e. without using an intermediate connector, may tend to limit the size of the rotor.

[0037] According to another aspect, the orders to modify the pitch of the blade are furthermore directly transmitted to this blade, without passing through a sleeve for example.

[0038] The blade may further include one or more of the following features.

[0039] Alternatively, the pitch attachment may be closer to the leading edge attachment than to the trailing edge attachment.

[0040] The smallest distance between the leading edge of a section and the pitch attachment is then less than the smallest distance between the trailing edge of that section and the pitch attachment.

[0041] In other words, the pitch attachment is arranged on the leading edge side of the blade.

[0042] According to a possibility compatible with the previous ones, the pitch attachment may comprise a pitch yoke provided with two parallel pitch wings inseparable from said envelope, said two pitch wings respectively comprising two pitch orifices aligned along a pitch connection axis and configured to be crossed by the pitch connection rod along said pitch connection axis, said pitch yoke projecting from the envelope into a medium external to the blade.

[0043] The pitch attachment thus comprises a pitch clevis secured to the casing. In addition, the pitch attachment is then arranged outside the internal space of the body so that it can be easily connected to a pitch connecting rod.

[0044] According to a possibility compatible with the previous ones, the leading edge attachment may comprise a leading edge yoke provided with two leading edge wings inseparable from said envelope, said two leading edge wings respectively comprising two leading edge orifices aligned along a leading edge axis and configured to be crossed by the leading edge connecting rod along said leading edge axis, said leading edge yoke projecting from the envelope into a medium external to the blade.

[0045] The leading edge attachment thus comprises a leading edge yoke secured to the envelope. In addition, the leading edge attachment is then arranged outside the internal space of the body. This arrangement can facilitate the connection of an inter-blade drag damper, i.e. one that extends between two adjacent blades.

[0046] If necessary, each step wing of the previously described step attachment can be attached to both leading edge wings.

[0047] The pitch attachment and the leading edge attachment can together form a compact composite material fitting.

[0048] Alternatively, the leading edge attachment may comprise two leading edge orifices provided in the envelope on either side of said internal space along a leading edge axis, the two leading edge orifices being configured to be traversed by the leading edge connecting rod along said leading edge axis.

[0049] In this case, a drag damper extends partially into the internal space through which the leading edge connecting rod passes. This arrangement may tend to reduce the aerodynamic drag of the rotor.

[0050] According to a possibility compatible with the previous ones, the trailing edge attachment may comprise a trailing edge yoke provided with two parallel trailing edge wings inseparable from said envelope, said two trailing edge wings respectively comprising two trailing edge orifices aligned along a trailing edge axis and configured to be crossed by the trailing edge connecting rod along said trailing edge axis, said trailing edge yoke projecting from the envelope into a medium external to the blade.

[0051] The trailing edge attachment then comprises a trailing edge yoke secured to the envelope. In addition, the trailing edge attachment is then arranged outside the internal space of the body. This arrangement can facilitate the connection of an inter-blade drag damper, i.e. one that extends between two blades.

[0052] Alternatively, the trailing edge attachment may comprise two trailing edge orifices provided in the envelope on either side of said internal space along a trailing edge axis, the two trailing edge orifices being configured to be traversed by the trailing edge connecting rod along said trailing edge axis.

[0053] In this case, a drag damper extends partially into the internal space, being crossed by the trailing edge connecting rod. This arrangement may tend to optimize the aerodynamic drag of the rotor.

[0054] In this context, according to a first embodiment the attachment body can comprise: a pitch attachment provided with two parallel pitch wings inseparable from said envelope, said two pitch wings respectively comprising two pitch orifices aligned along a pitch connection axis and configured to be traversed by the pitch connection rod along said pitch connection axis, said pitch yoke projecting from the envelope into a medium external to the blade, a leading edge attachment comprising a leading edge yoke provided with two parallel leading edge wings inseparable from said envelope, said two leading edge wings respectively comprising two leading edge orifices aligned along a leading edge axis and configured to be traversed by the leading edge connection rod along said leading edge axis, said leading edge yoke projecting from the envelope into a medium external to the blade,and a trailing edge attachment comprising a trailing edge yoke provided with two parallel trailing edge wings inseparable from said envelope, said two trailing edge wings respectively comprising two trailing edge orifices aligned along a trailing edge axis and configured to be crossed by the trailing edge connecting rod along said trailing edge axis, said trailing edge yoke projecting from the envelope into a medium external to the blade.

[0055] This first achievement can for example be used to obtain a compact blade foot.

[0056] According to a second embodiment, the attachment body can comprise: a pitch attachment provided with two parallel pitch wings inseparable from said envelope, said two pitch wings respectively comprising two pitch orifices aligned along a pitch connection axis and configured to be traversed by the pitch connection rod along said pitch connection axis, said pitch yoke projecting from the envelope into a medium external to the blade, a leading edge attachment comprising two leading edge orifices arranged in the envelope on either side of said internal space along a leading edge axis, the two leading edge orifices being configured to be traversed by the leading edge connection rod along said leading edge axis, and a trailing edge attachment comprising two trailing edge orifices arranged in the envelope on either side of said internal space along a trailing edge axis,the two trailing edge orifices being configured to be crossed by the trailing edge connecting rod along said trailing edge axis.

[0057] This second embodiment can, for example, be used to obtain an aerodynamically optimized blade root.

[0058] According to a possibility compatible with the previous ones, the connection attachment may comprise, for each connection rod, a set of two connection orifices provided in the casing, for example on either side of said internal space, along a connection axis configured to be merged with a connection rod.

[0059] Where appropriate, the trailing edge axis, the leading edge axis and the connecting axis may be parallel to each other. The pitch connecting axis may then lie in a plane perpendicular to these trailing edge, leading edge and connecting axes.

[0060] According to a possibility compatible with the previous ones, the envelope may comprise a layer of composite materials surrounding said internal space and extending the running part, said envelope comprising a laminated reinforcement at least at the level of the trailing edge attachment and the leading edge attachment.

[0061] The laminated reinforcement can strengthen the envelope, particularly at the parts forming the trailing edge attachment and the leading edge attachment.

[0062] In addition to a blade, the invention relates to a rotor provided with a rotor head, the rotor comprising at least one laminated spherical stop, the laminated spherical stop comprising a laminated central part inserted between a first frame and a second frame, the second frame being fixed to the rotor head.

[0063] This rotor then comprises at least one blade according to the invention, said rotor comprising at least two said connecting rods passing through the connecting attachment and the second frame, the rotor comprising a pitch connecting rod passing through the pitch attachment and a pitch articulation of a pitch rod, the rotor comprising a leading edge connecting rod passing through the leading edge attachment and a leading edge articulation of a first drag damper, the rotor comprising a trailing edge connecting rod passing through the trailing edge attachment and a trailing edge articulation of a second drag damper.

[0064] According to one possibility, the rotor may comprise at least three blades according to the invention, the trailing edge attachment of a particular blade may be connected by a drag damper to the leading edge attachment of the blade which follows according to a direction of rotation of the rotor and the leading edge attachment of the particular blade is connected by another drag damper to the trailing edge attachment of the blade which precedes according to said direction of rotation.

[0065] Each damper can act as a first drag damper with respect to one blade and a second drag damper with respect to an adjacent blade.

[0066] Furthermore, an aircraft may comprise a rotor according to the invention.

[0067] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent: there figure 1 , a perspective view of a blade according to the invention, the figure 2 , a perspective view of a blade according to the invention, the figure 3 , a partial view of a rotor having a blade according to the invention, and the figure 4 , a local section of a rotor having a blade according to the invention.

[0068] Elements present in several distinct figures are assigned a single reference.

[0069] Three directions X, Y and Z orthogonal to each other are attached to the blades of the figures 1 à 4 .

[0070] The X direction is called longitudinal and extends along the blade span. Another Y direction is called transverse and extends along a direction parallel to the blade sections. The third Z direction is called vertical and extends along the blade thickness.

[0071] THE figures 1 et 2 present examples of blades 1 according to the invention.

[0072] Whatever the realization and with reference to the figure 1 , this blade 1 comprises longitudinally, namely along its span, a blade root 10 which is extended by an aerodynamic running part 5. The running part 5 extends to a free end 6.

[0073] The blade foot 10 comprises an attachment body 20 made of single-piece composite materials, namely a single piece.

[0074] The attachment body 20 is hollow which tends to optimize its mass.

[0075] The attachment body 20 comprises in particular an envelope 25 delimiting an empty internal space INT. This envelope 25 surrounds the internal space, possibly radially relative to the pitch axis AXPAS of the blade. This envelope 25 therefore completely surrounds a section of the pitch axis AXPAS of the blade 1. In other words, the pitch axis AXPAS passes through the internal space INT.

[0076] The envelope 25 made of composite materials may comprise a stack of several composite plies of different orientations. Plies of the attachment body 20 may extend into the current portion 5.

[0077] In another aspect, the fastener body 20 incorporates various fasteners 30, 40, 50, 60. The term "integrates" means that the fasteners are integral parts of the fastener body 20, and not fasteners attached to the fastener body 20 by separable screwing or other means.

[0078] Thus, the attachment body 20 incorporates a pitch attachment 30 to be connected to a pitch lever 36 capable of rotating the blade around a pitch axis AXPAS. The pitch lever 36 is shown schematically so as not to weigh down the figure 1 . This pitch attachment 30 may be crossed along a pitch connection axis AXLP by a pitch connection rod 35 connected to a pitch lever 36, and for example to an articulation of the pitch lever 36. For example, such a pitch connection rod 35 comprises a screw, or even a nut, a pin or the like. According to one example, the pitch lever 36 comprises a pitch ball joint, the pitch connection rod 35 passing through a first part of the pitch attachment 30, the pitch ball joint and a second part of the pitch attachment 30.

[0079] Optionally, the pitch attachment 30 can be positioned on the leading edge BA side of the blade 1.

[0080] According to one possibility, the pitch attachment 30 may comprise a pitch yoke 37. This pitch yoke 37 may be a female yoke comprising two parallel pitch wings 31, 32 inseparable from the casing 25. A pitch lever 36 may extend between the two pitch wings 31, 32 to be articulated by the pitch connecting rod 35 to the blade 1. For this purpose, the two pitch wings 31, 32 respectively comprise two pitch orifices 33, 34 aligned along the pitch connecting axis AXLP and configured to be crossed by the pitch connecting rod 35.

[0081] Furthermore, the pitch clevis 37 projects from the envelope 25 in an EXT medium outside the blade 1.

[0082] In addition, the attachment body 20 incorporates a connection attachment 60 to be connected to a rotor head, and for example to a laminated spherical stop 95 fixed to the rotor head. This connection attachment 60 may be crossed by at least two connection rods 65, 75 connected to a first frame 96 of a laminated spherical stop 95 along a connection axis AXLC1, AXLC2. For example, each connection rod 65, 75 comprises a screw, or even a nut, a pin or the like. According to one example, each connection rod 65, 75 passes through a first part of the connection attachment 60, the first frame 96 and then a second part of the connection attachment 60.

[0083] The connecting clip 60 may comprise a respective connecting rod connection set 67, 77 for connection to the rotor head.

[0084] Regardless of the number of sets, each set 67, 77 comprises two connection holes 63-64, 73-74. The two connection holes 63-64, 73-74 of the same connection set 67, 77 are provided in the casing 25, for example on either side of the internal space INT or being offset outside the internal space parallel to the pitch axis as illustrated. Each connection hole 63-64, 73-74 passes right through a portion of the casing 25. The two connection holes 63-64, 73-74 of the same connection set 67, 77 are aligned along a connection axis AXLC1, AXLC2 configured to allow a connection rod 65, 75 to pass through.

[0085] For example, the casing 25 comprises a first upper bearing surface 61 provided with a first upper connection orifice 63 and a first lower bearing surface 62 provided with a first lower connection orifice 64 located in line with the first upper connection orifice 63 along a first connection axis AXLC1. In addition, the casing 25 comprises a second upper bearing surface 71 provided with a second upper connection orifice 73 and a second lower bearing surface 72 provided with a second lower connection orifice 74 located in line with the second upper connection orifice 73 along a second connection axis AXLC2. A first connection rod 65 can thus pass through the first upper connection orifice 63, a frame of a laminated spherical stop 95, then the first lower connection orifice 64.In addition, a second connecting rod 75 can thus pass through the second upper connecting orifice 73, the aforementioned frame of the laminated spherical stop 95, then the second lower connecting orifice 74.

[0086] In addition, the attachment body 20 incorporates a leading edge attachment 40 for connection to a first drag damper 81. The first drag damper 81 is shown schematically so as not to weigh down the figure 1 . The leading edge attachment 40 is positioned on the leading edge BA side of the blade 1.

[0087] This leading edge attachment 40 may be traversed along a leading edge axis AXLBA by a leading edge connecting rod 45 connected to a first drag damper 81, and for example to an articulation of the first drag damper 81. For example, such a leading edge connecting rod 45 comprises a screw or even a nut, a pin or the like. According to one example, this articulation comprises a leading edge ball joint, the leading edge connecting rod 45 passing through a first part of the leading edge attachment 40, the leading edge ball joint and a second part of the leading edge attachment 40.

[0088] Finally, the attachment body 20 incorporates a trailing edge attachment 50 to be connected to a second drag damper 82. The second drag damper 82 is shown schematically so as not to weigh down the figure 1 . This trailing edge attachment 50 may be traversed along a trailing edge axis AXLBF by a trailing edge connecting rod 55 connected to the second drag damper 82, and for example to an articulation of the second drag damper 82. For example, such a trailing edge connecting rod 55 comprises a screw or even a nut, a pin or the like. According to one example, this articulation hinge comprises a trailing edge ball joint, the trailing edge connecting rod 55 passing through a first part of the trailing edge attachment 50, the trailing edge ball joint and a second part of the trailing edge attachment 50.

[0089] Optionally, the pitch attachment 30 may be closer to the leading edge attachment 40 than to the trailing edge attachment 50.

[0090] Furthermore, the trailing edge axis AXLBF, the leading edge axis AXLBA and the connecting axes AXLC1, AXLC2 may be parallel. The pitch connecting axis AXLP may then lie in a plane perpendicular to these trailing edge axes AXLBF, leading edge axis AXLBA and connecting axes AXLC1, AXLC2.

[0091] According to another characteristic independent of the previous ones, the envelope 25 is made of composite materials. The envelope 25 may comprise a layer 26 made of composite materials, this layer 26 may surround the internal space INT. In addition, this layer 26 may extend the current part 5, for example by having common folds with the current part 5.

[0092] The envelope 25 may further comprise at least one laminated reinforcement 27 secured to the layer 26, for example at least at the level of the trailing edge attachment 50 and / or the leading edge attachment 40.

[0093] There figure 1 illustrates in this context a first example of the embodiment of the leading edge 40 and trailing edge 50 attachments.

[0094] According to this first example, the leading edge attachment 40 comprises two leading edge orifices 43, 44 arranged in the casing 25 on either side of the internal space INT along a leading edge axis AXLBA. Each leading edge orifice 43, 44 passes through a part of the casing 25 from one side to the other. The leading edge connecting rod 45 can thus pass successively, along the leading edge axis AXLBA, through a leading edge orifice 43, a first drag damper 81 present in the internal space INT and then the other leading edge orifice 44.

[0095] Likewise, the trailing edge attachment 50 comprises two trailing edge orifices 53, 54 provided in the casing 25 on either side of the internal space INT along a trailing edge axis AXLBF. Each trailing edge orifice 53, 54 passes through a portion of the casing 25 from one side to the other. The trailing edge connecting rod 55 can thus pass successively, along the trailing edge axis AXLBF, through a trailing edge orifice 53, a second drag damper 82 present in the internal space INT and then the other trailing edge orifice 54.

[0096] There figure 2 illustrates a second example of embodiment of the leading edge 40 and trailing edge 50 attachments.

[0097] The leading edge attachment 40 comprises a leading edge yoke 47. This leading edge yoke 47 may be a female yoke comprising two parallel leading edge wings 41, 42 inseparable from the envelope 25. A first drag damper 81 may extend between the two leading edge wings 41, 42 to be articulated by a leading edge connecting rod 45 to the blade 1. For this purpose, the two leading edge wings 41, 42 respectively comprise two leading edge orifices 43, 44 aligned along a leading edge axis AXLBA and configured to be traversed by the leading edge connecting rod 45.

[0098] Furthermore, the leading edge yoke 47 projects from the envelope 25 in the middle EXT outside the blade 1.

[0099] Optionally, each step wing 31, 32 is attached to the two leading edge wings 41, 42.

[0100] Likewise, the trailing edge attachment 50 comprises a trailing edge yoke 57. This trailing edge yoke 57 may be a female yoke comprising two parallel trailing edge wings 51, 52 inseparable from the envelope 25. A second drag damper 82 may extend between the two trailing edge wings 51, 52 to be articulated by a trailing edge connecting rod 55 to the blade 1. For this purpose, the two trailing edge wings 51, 52 respectively comprise two trailing edge orifices 53, 54 aligned along a trailing edge axis AXLBF and configured to be traversed by the trailing edge connecting rod 55.

[0101] Furthermore, the trailing edge cap 57 projects from the envelope 25 in the middle EXT outside the blade 1.

[0102] THE figures 1 et 2 illustrate two examples of implementation. However, it is possible to obtain other implementations by combining the examples of the figures 1 et 2 . Thus, one of the leading edge 40 and trailing edge 50 attachments of the figure 1 could be replaced by the corresponding attachment of the figure 2 .

[0103] There figure 3 has a rotor 90 provided with a blade 1 previously described. Optionally, this rotor 90 can be arranged on an aircraft 100. The blade illustrated is of the type of the figure 1 , but could be of the type of the figure 2 or of an alternative type.

[0104] The rotor 90 is provided with a rotor head 91 carrying at least one blade 1. The reference 1 is used to name any blade according to the invention, the references 101, 102 and 103 being used to designate particular blades.

[0105] The rotor 90 may comprise a laminated spherical stop 95 per blade 1, each blade 1 then being articulated to the rotor head 91 by a corresponding laminated spherical stop 95. Such a blade 1 may then have, relative to the rotor head 91, freedom of rotational movement around a concurrent pitch axis AXPAS, a flapping axis AXBAT and a drag axis AXTRA.

[0106] In reference to the figure 4 , the rotor head 91 may comprise a cell 92 per blade 1 housing a laminated spherical stop 95. This laminated spherical stop 95 may comprise a laminated central part 97 inserted between a first frame 96 and a second frame 98. The second frame 98 may be secured to the rotor head 91 by conventional means 88, 89. In addition, the first frame 96 is secured to the root 10 of the blade 1 via the connection rods 65, 75.

[0107] In reference to the figure 3, a connecting rod of pitch 35 passes through the attachment of pitch 30 of the blade 1 and a pitch articulation of a connecting rod of pitch 36.

[0108] Additionally, a leading edge connecting rod 45 passes through the leading edge attachment 40 and a leading edge hinge of a first drag damper 81. Similarly, a trailing edge connecting rod 55 passes through the trailing edge attachment 50 and a trailing edge hinge of a second drag damper 82.

[0109] Optionally, the rotor 90 may comprise at least three blades 101, 102, 103. In this case, the second drag damper 82 of a particular blade 101 may be articulated to the leading edge attachment 40 of the blade 102 which follows according to the direction of rotation 104 of the rotor 90. In addition, the first drag damper 81 of the particular blade 101 may be articulated to the trailing edge attachment 50 of the blade 103 which precedes according to the direction of rotation 104.

[0110] Naturally, the present invention is subject to numerous variations in its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes. It is of course conceivable to replace a means described by another means without departing from the scope of the present invention, which is defined by the appended claims.

Claims

1. Blade (1) comprising a blade root (10) extended by an aerodynamic running part (5) which extends up to a free end (6), characterized in that the blade root (10) comprises a single-piece attachment body (20) made of composite materials, the attachment body (20) being hollow and having an envelope (25) delimiting an empty internal space (INT), the attachment body (20) integrating a pitch attachment (30) configured to be passed through by a pitch connecting rod (35) connected to a pitch lever (36), the attachment body (20) integrating a leading edge attachment (40) configured to be passed through by a leading edge connecting rod (45) connected to a first lead-lag damper (81), the attachment body (20) integrating a trailing edge attachment (50) configured to be passed through by a trailing edge connecting rod (55) configured to be connected to a second lead-lag damper (82), the attachment body (20) integrating a connecting attachment (60) configured to be passed through by at least two connecting rods (65, 75) connected to a first frame (96) of a laminate spherical abutment (95).

2. Blade according to claim 1, characterized in that said pitch attachment (30) is closer to the leading edge attachment (40) than to the trailing edge attachment (50).

3. Blade according to either one of claims 1 to 2, characterized in that said pitch attachment (30) includes a pitch yoke (37) provided with two parallel pitch vanes (31, 32), inseparable from said envelope (25), said two pitch vanes (31, 32) respectively comprising two pitch orifices (33, 34) aligned about a pitch connecting axis (AXLP) and configured to be passed through by the pitch connecting rod (35) about said pitch connecting axis (AXLP), said pitch yoke (37) projecting from the envelope (25) into an environment (EXT) outside of the blade (1).

4. Blade according to any one of claims 1 to 3, characterized in that said leading edge attachment (40) includes a leading edge yoke (47) provided with two parallel leading edge vanes (41, 42), inseparable from said envelope (25), said two leading edge vanes (41, 42) respectively comprising two leading edge orifices (43, 44) aligned about a leading edge axis (AXLBA) and configured to be passed through by the leading edge connecting rod (45) about said leading edge axis (AXLBA), said leading edge yoke (47) projecting from the envelope (25) into an environment (EXT) outside of the blade (1).

5. Blade according to claims 3 and 4, characterized in that each pitch vane (31, 32) is coupled with the two leading edge vanes (41, 42).

6. Blade according to any one of claims 1 to 3, characterized in that said leading edge attachment (40) includes two leading edge orifices (43, 44) provided in the envelope (25) on either side of said internal space (INT) about a leading edge axis (AXLBA), the two leading edge orifices (43, 44) being configured to be passed through by the leading edge connecting rod (45) about said leading edge axis (AXLBA).

7. Blade according to any one of claims 1 to 6, characterized in that said leading edge attachment (50) includes a trailing edge yoke (57) provided with two parallel trailing edge vanes (51, 52), inseparable from said envelope (25), said two trailing edge vanes (51, 52) respectively comprising two trailing edge orifices (53, 54) aligned about a trailing edge axis (AXLBF) and configured to be passed through by the trailing edge connecting rod (55) about said trailing edge axis (AXLBF), said trailing edge yoke (57) projecting from the envelope (25) into an environment (EXT) outside of the blade (1).

8. Blade according to any one of claims 1 to 6, characterized in that said trailing edge attachment (50) includes two trailing edge orifices (53, 54) provided in the envelope (25) on either side of said internal space (INT) about a trailing edge axis (AXLBF), the two trailing edge orifices (53, 54) being configured to be passed through by the trailing edge connecting rod (55) about said trailing edge axis (AXLBF).

9. Blade according to claims 3, 4 and 7, characterized in that the attachment body (20) includes a pitch attachment (30) according to claim 3, a leading edge attachment (40) according to claim 4, and a trailing edge attachment (50) according to claim 7.

10. Blade according to claims 3, 6 and 8, characterized in that the attachment body (20) comprises a pitch attachment (30) according to claim 3, a leading edge attachment (40) according to claim 6, and a trailing edge attachment (50) according to claim 8.

11. Blade according to any one of claims 1 to 10, characterized in that said connecting attachment (60) includes, for each connecting rod (65, 75), a clearance (67, 77) of two connecting orifices (63-64, 73-74), provided in the envelope (25) about a connecting axis (AXLC1, AXLC2) configured to be combined with a connecting rod (65, 75).

12. Blade according to any one of claims 1 to 11, characterized in that said envelope (25) includes a layer (26) made of composite materials surrounding said internal space (INT) and extending the running part (5), said envelope (25) including a stratified reinforcement (27) at least at the trailing edge attachment (50) and at the leading edge attachment (40).

13. Rotor (90) provided with a rotor head (91), the rotor (90) comprising at least one laminate spherical abutment (95), the laminate spherical abutment (95) comprising a laminate central part (97) inserted between a first frame (96) and a second frame (98), the second frame (98) being fixed to the rotor head (91), characterized in that the rotor (90) comprises at least one blade (1) according to any one of claims 1 to 12, said rotor (90) comprising at least two said connecting rods (65, 75) passing through said connecting attachment (60) and said second frame (98), said rotor (90) comprising a pitch connecting rod (35) passing through said pitch attachment (30) and a pitch joint of a pitch connecting rod (36), said rotor (90) comprising a leading edge connecting rod (45) passing through said leading edge attachment (40) and a leading edge joint of a first lead-lag damper (81), said rotor (90) comprising a trailing edge connecting rod (55) passing through said trailing edge attachment (50) and a trailing edge joint of a second lead-lag damper (82).

14. Rotor according to claim 13, characterized in that the rotor (90) comprising at least three blades (101, 102, 103) according to any one of claims 1 to 12, the trailing edge attachment of a particular blade (101) is connected by a lead-lag damper (82) to the leading edge attachment of the blade (102), which follows along a direction of rotation (104) of the rotor (90) and the leading edge attachment of the particular blade (101) is connected by another lead-lag damper (81) to the trailing edge attachment of the blade (103) which precedes along said direction of rotation (104).

15. Aircraft (100), characterized in that the aircraft (100) includes a rotor (90) according to either one of claims 13 to 14.