TURBOMACHINE MODULE COMPRISING VARIABLE PITCH BLADES

Abstract

The invention relates to a turbomachine module with a longitudinal axis, comprising a plurality of variable-pitch blades (2) and a pitch-changing system (20) for changing the pitch of said blades, each blade comprising a pad mounted so as to be movable about a pitch axis in a support member, the pitch-changing system comprising at least one control means connected to the pad of at least one of the blades to control its pitch. According to the invention, the pitch-changing system comprises rocker assemblies (32) arranged regularly alternating with blades around the longitudinal axis and separated by at least one blade, each rocker assembly being connected by articulated links to the adjacent blades, being secured to the support member of at least one of the blades, and being configured to transmit the rotational movement of the blade controlled by the control means to at least one other variable-pitch blade. Figure for the abstract: Fig.5

Description

Title of the invention: TURBOMACHINE MODULE COMPRISING VARIABLE PITCH BLADES Technical field of the invention

[0001] The present invention relates to the aeronautical field, in particular aircraft propulsion. It relates to a turbomachine module comprising variable-pitch blades and more particularly to a system for changing the pitch of the variable-pitch blades. Technological background

[0002] Many turbomachines, such as turbojets or turboprops, are equipped with variable-pitch blades. The different operating modes and positions of the variable-pitch blades allow them to adapt to various turbomachine speeds.

[0003] These pitched vanes may be, for example, stator vanes which are known by the English acronym "OGV" for Outlet Guide Vane and which are arranged around the longitudinal axis of the turbomachine. These stator vanes radially cross a flow and are placed downstream of moving vanes in order to straighten the flow at the outlet of these moving vanes. For this purpose, the variable pitch vanes are connected to a pitch change system which is configured so as to vary the pitches or inclinations of these around their pitch axis during a flight.

[0004] The pitch change system generally comprises a jack which is connected to the variable-pitch blades by means of connecting means. These connecting means can transmit a torque to all of the blades so that they have the same pitch during a given operating mode. These connecting means comprise, for example, a control ring movable in translation or in rotation, levers, bell cranks, a gear device, or a chain of connecting rods.

[0005] These connecting means, however, have drawbacks. For example, in the case of a control ring pivoting around the longitudinal axis and associated with bell cranks which are mounted in an articulated manner on a casing of the turbomachine and on the control ring, it is necessary to provide an annular zone to house the control ring, which can complicate the assembly. Furthermore, it is necessary to provide a degree of freedom in translation on the ball joint which is located at the level of the bell crank and the control ring or on the bell crank.

[0006] In the case of a control ring moving in translation and associated with connecting rods which connect the control ring to the foot of at least one blade, the guidance in translation must be precise. Indeed, the root of each blade is integral with a guide column which slides in a socket of the control ring. This configuration also requires a clean environment around the control ring to obtain precise guidance.

[0007] A gear device equipping a pitch change system requires high lubrication. On the other hand, the contact between the different teeth generates metal filings, i.e. wear of the gear device. Furthermore, the gear device can impact the mass of the pitch change system by arranging numerous wheels or pinions equipped with teeth.

[0008] When the pitch change system is equipped with a chain of connecting rods, adjustment can be tedious and misadjustment could occur during operation. Indeed, the connecting rods are arranged around the longitudinal axis and are connected to each other as well as to the blade roots by means of fixing rods. In order to reduce premature wear at the metal-metal contacts, for example between the rods and the connecting rods, a sliding ball joint must be considered.

[0009] In most cases, the pitch change system is installed in an area where the pylon is located, allowing the turbomachine to be suspended under the wing of the aircraft. The presence of the pylon can complicate the arrangement of the pitch change system and does not allow the installation of the connecting means described above.

[0010] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0011] The objective of the present invention is to provide a simple, economical and robust solution, which makes it possible to safely and efficiently integrate setting means providing uniform and simultaneous setting on all the variable-pitch blades.

[0012] We achieve this objective in accordance with the invention by means of a longitudinal axis turbomachine module, in particular an aircraft module, the module comprising a plurality of variable-pitch blades about the longitudinal axis and a system for changing the pitch of the variable-pitch blades, each variable-pitch blade comprising a stud mounted so as to move about a pitch axis in a support member, the pitch change system comprising at least one control means connected to the stud of at least one of the variable-pitch blades so as to control its rotation about its pitch axis, the pitch change system further comprising rocker assemblies which are regularly arranged alternating with variable-pitch blades about the longitudinal axis and which are separated by at least one variable-pitch blade, each rocker assembly being connected by articulated links to the adjacent variable-pitch blades, each assembly rocker being secured to the support member of at least one of the variable-pitch blades, each rocker assembly being configured to transmit the rotational movement of the variable-pitch blade controlled by the control means to at least one other variable-pitch blade.

[0013] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, this configuration provides identical and simultaneous angular setting from one variable-pitch blade to another; the kinematics are perfect, that is to say that it retransmits to the theoretical exactly the same angle from one variable-pitch blade to another without any dispersion. With such a configuration, there is also no need for an additional flexible part or additional degree of freedom such as sliding ball joints. Added to this is the fact that the arrangement of the rocker assembly makes it possible to free up certain spaces which make it possible to reduce the mass of the system, or to provide in a simple manner the passage of services.

[0014] The turbomachine module also comprises one or more of the following features and / or steps, taken alone or in combination:

[0015] - the variable-pitch blade whose support member is connected to a rocker assembly is different from the variable pitch vane which is controlled by the control means.

[0016] - each rocker assembly comprises a rocker finger extending along a radial axis, two first levers each pivotally mounted on the tilting finger and two second levers each articulated with a first lever, each second lever being rotationally secured to a variable-pitch blade stud.

[0017] - the articulated connection between a first lever and a second lever is a connection kneecap.

[0018] - each support member is connected to a stator of the turbomachine and in that a connecting element connects the tilting finger to the support member, the tilting finger being mounted to be able to rotate relative to said connecting element along the radial axis.

[0019] - each tilting finger is angularly arranged equidistantly between two adjacent variable-pitch blades.

[0020] - the tilting fingers are arranged at a radial distance from the longitudinal axis identical or at least one of the tilting fingers is arranged at a different radial distance.

[0021] - the pitch change system comprises a plate mounted integral in rotation on the pad of each variable-pitch blade and on which each second lever is pivotally mounted.

[0022] - the first levers and the second levers each have a general shape in Y.

[0023] - the pitch change system comprises a linkage mechanism comprising a control arm which is on the one hand secured to the variable-pitch vane block controlled by the control means and which is on the other hand connected to the movable body of the control means.

[0024] - the pitch change system comprises several control means distributed around the longitudinal axis and in that each control means is connected to the pad of a single variable-pitch blade via the control arm and each rocker assembly which is arranged between two variable-pitch blades is connected to a single support member of a variable-pitch blade different from the variable-pitch blade controlled by the control means.

[0025] - a control means is intended to control via one or more follower assemblies at least three variable pitch blades.

[0026] - - the plate is formed in one piece with the blade stud.

[0027] The invention relates to a turbomachine, in particular for an aircraft, comprising at least one turbomachine module having any one of the aforementioned characteristics. Brief description of the figures

[0028] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0029] - [Fig.l] is a perspective view of an annular row of pitched vanes variable according to the invention;

[0030] - [Fig.2] is a perspective and detail view of an example of a system of change of pitch of variable-pitch blades according to the invention;

[0031] - [Fig.3] is an axial sectional view of an example of a blade root with shim variable according to the invention;

[0032] - [Fig.4] is a top and partial view of a pair of variable pitch vanes cooperating with a pitch change system according to the invention; and

[0033] - [Fig.5] is a perspective and partial view of a gear change system not comprising at least one control means according to the invention. Detailed description of the invention

[0034] [Fig.l] represents a turbomachine module 1 with longitudinal axis X. The turbomachine is intended to be mounted on an aircraft. The turbomachine may be a turbo-engine, a turbojet, a turbofan, or may comprise moving fan blades or moving blades of at least one propeller which are shrouded or unfaired.

[0035] The turbomachine module 1 comprises variable-pitch blades 2 which are distributed around the longitudinal axis X. These variable-pitch blades 2 may be moving blades or stator blades.

[0036] In the present invention, the term "stator blade" or "fixed blade" means a blade that is not driven in rotation about the longitudinal axis X of the turbomachine. In other words, the stator blade is distinct from and opposite a moving or rotor blade of the turbomachine. The stator blades and the moving blades are generally arranged in the form of an annular row and the annular rows of stator blades are arranged upstream and / or downstream of the annular rows of moving blades along the longitudinal axis X.

[0037] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to the circulation of gases or air flows in the turbomachine and here along the longitudinal axis X. The terms "axial" and "axially" are defined with respect to the longitudinal axis X. The terms "external", "external", "internal", "internal" and "radial" are defined with respect to a radial axis Z which extends from the longitudinal axis X and with respect to the distance from the longitudinal axis X. The radial axis is perpendicular to the longitudinal axis X.

[0038] In an exemplary embodiment, the moving blades are fan blades or propeller blades and the stator blades are outlet guide vanes, known by the English acronym “OGV” for Outlet Guide Vane which are placed downstream of the moving blades.

[0039] In another exemplary embodiment, the turbomachine 1 comprises a compressor assembly (not shown) and a turbine assembly (not shown) which are placed on either side of a combustion chamber (not shown) along the longitudinal axis X. The compressor assembly and the turbine assembly each comprise several rows of moving blades and stator blades which are alternated along the longitudinal axis X. The stator blades are known by the term "straightener" or by the English acronym "VSV" for Variable Stator Vane. These make it possible to straighten the flow which passes through them. The stator blades of the compressor assembly or of the turbine can be of variable pitch.

[0040] With reference to [Fig. 2], each variable-pitch blade 2 comprises a blade 4 that can pivot about a pitch axis A. Advantageously, but not limitatively, each variable-pitch blade 2 comprises a root 5a that is provided with a platform 5b. Each platform 5b is arranged between the blade 4 and a stud 3 allowing the rotation of each variable-pitch blade 2. Each stud 3 is mounted to move about the pitch axis. The platform 5b extends generally transversely relative to the pitch axis A of the variable-pitch blades 2.

[0041] Each blade 4 comprises a leading edge 4a and a trailing edge 4b ​​which are connected by an extrados surface 4e and an intrados surface 4i (visible in [Fig.l]). The pitch axis A extends substantially parallel to the radial axis Z. The pitch axis A may have an inclination of between 5° and 10° relative to the radial axis Z. The pivoting of the variable-pitch blades 2 makes it possible to modify their pitch angle and for one of the intrados surfaces 4i and extrados surface 4e to be more or less exposed to the air flow depending on the speed of the turbomachine.

[0042] [Fig.2] illustrates variable pitch blades 2 which are adjacent in the circumferential direction around the longitudinal axis X.

[0043] The turbomachine module comprises a plurality of support members 6 which each receive a pad 3. Each pad 3 is mounted movably around the setting axis A in a support member 6. The support members 6 are distinct from one another. The support members 6 are also distributed regularly around the longitudinal axis X. This configuration makes it possible to reduce the size between the blades 2, which makes it possible to install other members therein such as at least part of a pitch change system described later.

[0044] With reference to Figures 2, 3 and 4 which illustrate a part of the turbomachine module, the support members 6 are each connected to a stator 7 of the turbomachine. That is to say that these are fixed in rotation and in translation. The turbomachine 1 comprises an annular casing 8 centered on the longitudinal axis X. The annular casing 8 comprises an annular flange 9 which extends radially outwards. Each support member 6 comprises at least one lug 10 which is fixed on the annular flange 9 using fixing members (not shown). These fixing members can be screws, nuts, bolts, etc.

[0045] More precisely illustrated in Figures 2 and 3, each support member 6 comprises an annular wall 11 having an axis of revolution B which is centered on a wedging axis A. Each annular wall 11 extends between a first end 11a and a second end 11b along the axis of revolution B. The first end 11a is closed at least in part by a bottom wall 17. The second end 11b has an opening which is delimited by an annular edge 13. The opening opens into an internal housing 14 formed by the annular wall 11.

[0046] At least one bearing 16 is mounted in the housing 14 to ensure the centering and guiding of a stud 3. Preferably, two bearings 16 are mounted in each housing 14. In particular, each bearing 16 comprises an inner ring 16a and an outer ring 16b between which rolling members 16c are arranged. The latter may be balls or rollers. The inner ring 16a may be secured to an outer surface of the stud 3 and the outer ring 16b may be secured to the inner surface of the annular wall 11. The securing of the inner and outer rings 16a, 16b can be made by shrink-fitting. Alternatively, the annular wall 11 can act as an outer ring for each bearing 16. In this case, the inner surface of the annular wall 11 defines a rolling track for the rolling members 16c.

[0047] In the example of [Fig.3], each stud 3 is carried by a plate 27 described later in this description. Each stud 3 extends radially from a lower surface 27b of the plate 27. Advantageously, the plate 27 is formed in a single piece with the stud 3. Each platform 5b of the root 5a of a blade 2 is fixed to an upper surface 27a of the plate 27. The fixing can be carried out by bolt-type members or other suitable means at the platform 5b. Each stud 3 comprises a blind hole which opens at its free end (at a distance from the lower surface 27b).The bottom wall 17 comprises a radial section, centered on the wedging axis, which is inserted into the blind hole. The bottom wall 17 comprises a collar extending radially from the section and which is configured to cover the free end of the stud 3.

[0048] Alternatively, the plate 27 comprises a bore which passes through it radially on either side and which is passed through by the stud 3 which is formed in a single piece with the blade. In this case, the stud is housed in the housing 14 of the support member 6.

[0049] In the remainder of the description, the pad 3 carried by the plate 27 or the pad 3 carried by the blade 4 is considered to be the foot of the blade.

[0050] With reference to Figures 4 and 5, the turbomachine module comprises a pitch change system 20 configured to change the pitch of the blades 2 depending on the operating mode of the turbomachine. The pitch change system 20 comprises at least one control means 21 which is connected to the pad 3 of at least one of the variable-pitch blades 2 so as to control its rotation about its pitch axis A.

[0051] The control means 21 comprises a fixed body 23 and a body 24 that is movable relative to the fixed body 23. The control means 21 is connected to a fluid supply source (not shown) for supplying pressurized oil to chambers (not shown) that are formed between the fixed body 23 and the movable body 24. The movable body 24 here moves in translation along the longitudinal axis X. The movable body 24 comprises a rod 25 that extends along the longitudinal axis X. The rod 25 is arranged circumferentially between two adjacent variable-pitch vanes 2.

[0052] Advantageously, the fixed body 23 is connected to a stator 7 of the turbomachine so as to be immobile in rotation and in translation. In the present example, the stator is the annular casing 8. According to an example of assembly, the casing 8 comprises two panels 15 which extend axially from the flange 9. The control means 21 is arranged between these two panels 15 in order to maintain the control means 21 in position and make the assembly more reliable. Advantageously, but not limitingly, the flange 9 comprises an opening which passes through its wall on either side along the longitudinal axis X. A portion of the fixed body passes through the opening and is held on the flange 9.

[0053] In the example illustrated in [Fig.5], the pitch change system 20 comprises at least one connecting mechanism 22 which makes it possible to connect the or each control means 21 to at least one blade stud 3.

[0054] The connecting mechanism 22 comprises at least one control arm 26 which is integral with a stud 3 connected to a variable-pitch blade 2. The control arm 26 is also connected to the movable body 24 of the control means. In other words, the control arm 26 is integral with the stud 3 of the blade 2 which is controlled (directly) by the control means 21. The control arm 26 extends between a first end 26a and a second end 26b.

[0055] Advantageously, but not limitatively, the plate 27 is mounted integral in rotation with the stud 3 driving in rotation each variable-pitch blade 2. Each plate 27 is arranged radially between the support member 6 and the platform 5b of the blade 2. The plates 27 also each have a section (in a plane perpendicular to the setting axis A) which is rectangular. Of course, the section can be of different shape as long as the rotation of the stud 3 is not hindered and the plate 27 is not bulky.

[0056] In [Fig. 5], the movable body 24 of the control means 21 is connected to the plate 27 mounted on one of the pads 3 of the blade 2, here of the first blade 41 which is shown in [Fig. 5] and whose pad 3 is connected to the movable body 24 of the control means 21. The first end 26a of the control arm 26 is fixed to the plate 27 mounted on the pad 3 of the first variable-pitch blade 4L. Advantageously, but not limitingly, the control arm 26 is formed from a single piece (made of material) with the plate 27. This makes it easier to manufacture and assemble. The second end 26b of the control arm 26 is connected to a free end 25a of the rod 25 of the movable body 24 of the control means 21.

[0057] Advantageously, but not limitingly, the second end 26b of the control arm 26 comprises a fixing yoke 28 formed of two mounting lugs 28a, 28b. Alternatively, the second end 26b may comprise a single mounting lug. In this example, the two mounting lugs 28a, 28b are parallel to each other. Each mounting lug 28a, 28b is pierced with an orifice passing through it on either side. The axis of the orifices is here parallel to the radial axis. Here the free end 25a of the rod 25 is also pierced by an orifice with a radial axis. The holes of the ears 28a, 28b and of the free end 25a are crossed by a fixing pin 29. In this way, when the mobile body 24 moves in translation, a rotational movement is transmitted to the plate 27 via the control arm 26. The pin 3 of the first blade 41 which is carried by this plate 27 pivots in the corresponding support member 6.

[0058] According to this exemplary embodiment, the control arm 26 further comprises two bars 30a, 30b which extend on either side of the main body 31 of the control arm 26. The two bars 30a, 30b are fixed on the one hand to the plate 27 and on the other hand towards the second end 26 of the control arm 26.

[0059] According to an advantageous characteristic, the pitch change system 20 comprises several control means 21 which are distributed around the longitudinal axis X. Each control means 21 is arranged along the longitudinal axis X and acts directly on the pads 3 of the variable-pitch blades 2. However, the number of control means 21 is less than that of the variable-pitch blades 2. In the present example, there are three control means 21. Each control means 21 is connected to a variable-pitch blade pad 2 via a control arm 26. Each pad 3 of a variable-pitch blade 2 which is connected to a control means 21 is considered to be a controlled blade pad or a master pad. In other words, not all the blades 2 are connected to the control means via control arms 26 but only some of them.The other blade plots 2 not directly connected to the control means 21 via the control arm 26 are considered to be follower blade plots or slave plots. In particular, the number of controlled blade plots is equal to the number of control means 21 installed in the turbomachine module.

[0060] The pitch change system 20 further comprises at least one rocker assembly 32 which is arranged between two adjacent variable-pitch blades 2. Advantageously, rocker assemblies 32 are regularly arranged alternating with variable-pitch blades 2 around the longitudinal axis. More precisely, the rocker assemblies 32 are separated by a variable-pitch blade 2. Each rocker assembly is configured to transmit the rotational movement of the variable-pitch blade controlled by the control means to at least one other variable-pitch blade.

[0061] In [Fig. 5], a rocker assembly 32 is arranged between the first variable-pitch vane 41 (partially shown) and a second variable-pitch vane 42 (partially shown) adjacent to the plurality of variable-pitch vanes. The rocker assembly 32 is configured to transmit the rotation of at least the first vane 41 (controlled by the control means 21) to the adjacent second vane 42. In other words, the rocker assembly 32 makes it possible to transmit the rotation of the master vane pad to the follower vane pad. For this, each rocker assembly 32 is connected by articulated links to the adjacent variable-pitch vanes 2 between which it is arranged.

[0062] According to an advantageous, but not limiting, characteristic, each rocker assembly 32 is arranged radially outside the fixing yoke 28 of the control arm 26. In other words, the rocker assembly 32 extends radially outside the rod 25 of the mobile body.

[0063] Each rocker assembly 32 is connected to at least one support member 6 of the plurality of variable-pitch blades. For this, each rocker assembly 32 comprises a rocker finger 33 which extends along an axis C. This axis C is parallel to the radial axis Z. Each rocker finger 33 is angularly arranged equidistantly between two adjacent blades 2 around the longitudinal axis X. The axis of each rocker finger 33 is for example arranged at approximately 30° from the pitch axis A of each variable-pitch blade (the longitudinal axis being the center). The pitch of the blades 2 is then precise. However, the variable-pitch blades 2 which are located at midday (around the longitudinal axis) can be spaced by approximately 27° from the axis of a tilting finger 33 so as to take into account the installation of a pylon of the turbomachine. The pylon (not shown) connects the nacelle of the turbomachine to the aircraft, for example.

[0064] Advantageously, the tilting fingers 33 may be arranged at radial distances from the longitudinal axis X which are identical. Alternatively, the radial distances are different. For example, the inner end 33a of a tilting finger 33 of a tilting assembly 32 may be arranged 710 mm from the longitudinal axis X while the tilting finger 33 of another tilting assembly 32 may be located 720 mm from the longitudinal axis X. The tilting fingers 33 all have the same radial height. The angle transmitted to all the variable-pitch blades 2 remains identical. Such a configuration may be advantageous for the installation of utilities (not shown).

[0065] A connecting element 34 connects the tilting finger 33 to the support member 6. In particular, the support member 6 which is connected to the tilting assembly 32, in particular the tilting finger 33 in this exemplary embodiment, is the one which carries the stud of a variable-pitch blade not controlled by the control means 21, i.e. the second variable-pitch blade 42. In other words, the support member 6 which is connected to a tilting assembly 32 is different from the variable-pitch blade 2 which is controlled by a control means 21. The connection between the support member 6 and the tilting assembly 32 is a rigid connection, for example by embedding. In this case, the tilting finger 33 is fixed in position since the support members 6 are fixed because they are connected to the stator.

[0066] Advantageously, the connecting element 34 extends between a first end 34a and a second end 34b. The first end 34a comprises a ring 35 crossed by the tilting finger 33. The tilting finger 33 is advantageously mounted movably in the ring 35 of each rocker assembly 32. The rocker finger 33, fixed in position, is movable in rotation in other words relative to the support member 6. For this purpose, a bearing (not shown) is mounted in the ring 35. A self-lubricating bushing can also be provided in the ring 35. According to the example shown, the ring 35 is located in the lower part (close to the longitudinal axis X) of the rocker finger 33. The second end 34b of the connecting element 34 is fixed to the annular wall 11 of the support member 6.

[0067] According to an advantageous, but not limiting, characteristic, the connecting element 34 is formed in a single piece with the support member 6.

[0068] Each connecting element 34 has a determined length which makes it possible to place the tilting finger 33 at a predetermined distance (preferably equidistant) between two adjacent blades 2.

[0069] Each rocker assembly 32 comprises two first levers 36 and two second levers 37. The second levers 37 are mounted on either side of each blade stud 3. The first levers 36 are carried by the rocking finger 33, arranged between two adjacent blades 2, and are connected in an articulated manner to the second levers 37. More precisely, each first lever 36 is pivotally mounted on the rocking finger 33 and is articulated relative to a second lever 37. Each second lever 37 is pivotally mounted on the plate 27 integral in rotation with a blade stud. Advantageously, the articulation between a first lever 35 and a second lever 36 is a ball joint.

[0070] Advantageously, but not limitatively, the first levers 36 comprise a general Y shape. The first levers 36 comprise for example two branches 36a, 36b connected to a leg 36c. The free end 36aa, 36ba of each branch 36a, 36b of a first lever 36 is crossed by a pivot axis D which is transverse to the axis C of the tilting finger 33 (here parallel to the radial axis). The pivot axis D is perpendicular to the axis C of the tilting finger 33. More precisely still, the axis C of the tilting finger 33 is defined in the pivot plane of each first lever 36.

[0071] The second levers 37 also have a general Y shape. Each second lever 37 comprises, for example, two branches 37a, 37b connected to a leg 37c. The free end 37aa, 37ba of each branch of a second lever 37 is crossed by a pivot axis E which is transverse to the setting axis A of the blade studs. The setting axis A is defined in the pivot plane of each second lever 37.

[0072] The leg 37c of each second lever 37 comprises at its free end an orifice 38 passing through on either side along an axis perpendicular to the axis of pi vote E of the two branches 37a, 37b. The free end 36ca of the leg 36c of each first lever 36 is mounted in the orifice 38 of the free end 37ca of the leg 37c according to a ball joint. In other words, the first levers 36 are male levers and the second levers 37 are female levers. Alternatively, the leg 36c of each first lever 36 comprises an orifice and the free end of the leg 37c of each second lever 37 is mounted according to a ball joint in the orifice.

[0073] The directions of elongation of the legs 36c, 37c of the first lever 36 and of the second lever 37 which are linked by a ball joint form an obtuse angle. When the tilting finger 33 is positioned closer to the setting axes A (for example of the order of 27°), the angle formed by the legs 36c, 37c of a first and second lever 36, 37 is more closed and can be between 45° and 90°. The directions of the legs always form an angle in operation.

[0074] We will now describe the kinematic operation of the pitch change system 20. When each control means 21 is controlled to change the pitch of the blades 2, the movable body 24 moves in translation which causes the control arm 26 and thus the controlled blade stud 3 to pivot. The pivoting of the controlled blade stud 2 about its pitch axis A simultaneously causes the movement of the first and second levers 36, 37 arranged between two variable-pitch blades 2. The two first and second levers 36, 37 transmit the movement and the angular pitch to the studs of the other variable-pitch blades (follower blade studs).

[0075] A single control means 21 makes it possible to directly control (via the control arm 26) a single blade block 2 and to control via one or more rocker assemblies 32 at least two variable-pitch blade blocks 2 arranged adjacently around the longitudinal axis. Advantageously, a control means 21 can control via one or more rocker assemblies 32 at least three variable-pitch blades 2.

[0076] In this way, the rocker assemblies 32 make it possible to obtain a setting of all the variable-pitch blades in the same direction.

Claims

Claims

1. A turbomachine module with a longitudinal axis (X), in particular for an aircraft, the module comprising a plurality of variable-pitch blades (2) around the longitudinal axis (X) and a pitch-changing system (20) for the variable-pitch blades (2), each variable-pitch blade (2) comprising a stud (3) mounted so as to be movable around a pitch axis (A) in a support member (6), the pitch-changing system (20) comprising at least one control means (21) connected to the stud (3) of at least one of the variable-pitch blades so as to control its rotation around its pitch axis (A), characterized in that the pitch-changing system (20) further comprises rocker assemblies (32) which are regularly arranged alternating with the variable-pitch blades (2) around the longitudinal axis (X) and which are separated by at least one variable-pitch blade,each rocker assembly (32) being connected by articulated links to the adjacent variable-pitch blades (2), each rocker assembly (32) being secured to the support member (6) of at least one of the variable-pitch blades (2), each rocker assembly (32) being configured to transmit the rotational movement of the variable-pitch blade (2) controlled by the control means (21) to at least one other variable-pitch blade (2).,

2. Turbomachine module according to the preceding claim, characterized in that the variable-pitch blade (2) whose support member (6) is connected to a rocker assembly (32) is different from the variable-pitch blade (2) which is controlled by the control means (21).

3. Turbomachine module according to one of the preceding claims, characterized in that each rocker assembly (32) comprises a rocker finger (33) extending along a radial axis, two first levers (36) each pivotally mounted on the rocker finger (33) and two second levers (37) each articulated with a first lever (36), each second lever (37) being rotationally secured to a pad (3) of a variable-pitch blade (2).

4. Turbomachine module according to the preceding claim, characterized in that the articulated connection between a first lever (36) and a second lever (37) is a ball joint connection.

5. Turbomachine module according to one of claims 3 and 4, characterized in that each support member (6) is connected to a stator (7) of the turbomachine and in that a connecting element (34) connects the tilting finger (33) to the support member (6), the tilting finger (33) being mounted to be movable in rotation relative to said connecting element (34) along the radial axis.

6. Turbomachine module according to one of claims 3 to 5, characterized in that each tilting finger (33) is arranged angularly equidistant between two adjacent variable-pitch blades (2).

7. Turbomachine module according to one of claims 3 to 6, characterized in that the tilting fingers (33) are arranged at an identical radial distance from the longitudinal axis (X) or at least one of the tilting fingers (33) is arranged at a different radial distance.

8. Turbomachine module according to one of claims 2 to 6, characterized in that the pitch change system (20) comprises a plate (27) mounted integral in rotation on the stud (3) of each variable-pitch blade (2) and on which each second lever (37) is pivotally mounted.

9. Turbomachine module according to one of claims 3 to 8, characterized in that the first levers (36) and the second levers (37) each have a general Y shape.

10. Turbomachine module according to one of the preceding claims, characterized in that the pitch change system (20) comprises a connecting mechanism (22) comprising a control arm (26) which is on the one hand integral with the pad (3) of the variable-pitch blade (2) controlled by the control means (21) and which is on the other hand connected to the movable body (24) of the control means (21).

11. Turbomachine module according to claim 10, characterized in that the pitch change system (20) comprises several control means (21) distributed around the longitudinal axis (X) and in that each control means (21) is connected to the stud (3) of a single variable-pitch blade (2) via the control arm (26) and each rocker assembly (32) which is arranged between two variable-pitch blades is connected to a single support member (6) of a variable-pitch blade (2) different from the variable-pitch blade (2) controlled by the control means (21).

12. Turbomachine module according to any one of the preceding claims, characterized in that a control means (21) is intended to control via one or more follower assemblies (32) at least three blades

13. with variable timing (2). Turbomachine (1) comprising a turbomachine module according to any one of the preceding claims.

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