Turbine engine assembly comprising a variable-pitch stator vane equipped with a heating element and a connection housing

Abstract

The invention relates to an assembly of a turbine engine having a longitudinal axis (X), for an aircraft, the turbine engine comprising: - a variable-pitch stator vane (2) including a blade (4) and a pivot (5) which extends radially from the blade (4); - a pitch-change system (3) for changing the pitch of the stator vane; and - a heating element (26) comprising a first portion (26a), which is mounted in the blade (4), and a second portion (26b), which is connected to an electrical power supply source (30) of an electrical connection device (29). According to the invention, the electrical connection device (29) comprises a connection housing (31) which connects the second portion to a power supply harness (32a, 32b) which is coupled to the electrical power supply source, and the pivot comprises a main bore (33) in which the connection housing (31), constrained to rotate with the pivot, and the second portion (26b) are housed.

Description

Description TITLE: TURBOMACHINE ASSEMBLY COMPRISING A VARIABLE-TIMED STATOR VANE EQUIPPED WITH A HEATING ELEMENT AND A CONNECTION BOX Technical field of the invention

[0001] The present invention relates to the aeronautical field, in particular aircraft propulsion. It relates in particular to a variable-pitch stator blade equipped with a heating element and a connection box. Technological background

[0002] Many turbomachines, such as turbojets or turboprops, are equipped with variable-pitch stator blades. The variable-pitch stator blades are arranged around the longitudinal axis of the turbomachine and are generally placed upstream or downstream of the rotor blades, depending on the gas flow in the turbomachine, in order to direct the airflow at the outlet or towards these rotor blades at the correct angle. The pitch allows them to adapt to various speeds of the turbomachine. For this purpose, the variable-pitch stator blades are connected to a pitch-changing system that is configured to vary the pitch or inclination of the stator blades around their pitch axis during flight.

[0003] Stator blades can be fitted to a compressor of the turbomachine. The pitch change system comprises a control ring centered on the longitudinal axis and several levers, each of which is connected to a pivot of a stator blade and to the control ring. Each pivot is mounted in a corresponding housing of a turbomachine casing using bushings.

[0004] Stator blades can be subject to the formation of frost which can impair their operation and thus degrade the performance of the turbomachine. In this case, the variable pitch stator blades have been equipped with heating elements having a portion integrated into each blade of the stator blades. Each heating element is connected to a power cable which extends outside the blade at the base of the pivot and which is connected to a connection device electrical located outside the stator blade in an area near the pitch change system.

[0005] The power cables have an excess length to follow the rotational movement of the stator blades during the pitch change but which can interact with the pitch change system. The electrical connection device can also move during the rotation of the stator blades. Spacers have been considered to avoid interactions, however this results in a significant bulk in an area already constrained in terms of available space. Despite this, mechanical stress and deformation of the power cables between the heating elements in the moving reference, and the electrical connection device in the fixed reference are inevitable. This negatively impacts the durability and reliability of the heating elements.

[0006] Furthermore, the electrical assembly of the heating elements and the electrical connection device is difficult to implement reliably once the stator blades are already installed in the turbomachine due to the restricted space. The assembly of the pitch change system and the adjustment of the timing of the stator blades involve carrying out several operations of tightening and / or loosening of parts which require the stressing of the power cables which can affect their mechanical strength as well as those of electrical connectors, of the fixing between the heating element and the electrical connection device or of the heating element itself. The heating elements comprise over part of their length an insulating sheath which is rigid, fragile and sensitive to repeated or extreme mechanical stresses which can cause them to break.Heating element power cables typically include electrical insulation that is more flexible and offers better resistance to repeated stress than heating elements. Installation is also complex because the power cables must pass through the respective bushings and housings in the turbomachine casing before the pivots are engaged in their housings.

[0007] In addition, the heat transfer from the heating element power cables to the outside is limited by their exposure to the open air; the lack of cooling of their parts in the open air is a limiting factor for the electrical power flowing through the power cables and reduces the power density that can be integrated.

[0008] GB-A-2403778 also describes a heating element that is mounted within a turbomachine blade. In particular, this heating element is a heating mat. The heating element is connected to a cable having a significant length so that the blade includes various passages arranged radially below the pivot to make bends in the cable and contain the latter. One end of the cable is coupled to the heating element and another end of the cable is coupled to a power source by passing through a connection box (in two parts) mounted in the pivot. The power source is arranged outside the blade and the pivot. Such a configuration complicates the assembly and promotes energy losses due to the excess length of the elements in the blade and reduces their service life due to the mechanical stresses undergone.

[0009] There is a need to address some or all of the above drawbacks. Summary of the invention

[0010] The objective of the present invention is to provide a simple, robust and economical solution making it possible to reduce, or even eliminate, the mechanical stresses on the means for supplying the heating means of a variable-pitch stator blade in order to prevent the formation of frost while allowing it to be set.

[0011] We achieve this objective in accordance with the invention by means of a longitudinal axis turbomachine assembly, in particular for an aircraft, comprising: - a variable pitch stator vane comprising a blade and a pivot extending radially from one end of the blade, - a pitch change system configured to change the timing of the stator blade about its timing axis, the pivot being connected to the pitch change system, and - a heating element comprising a first portion mounted within the blade and a second portion connected to an electrical power source of an electrical connection device, the electrical connection device comprising a connection box connecting the second portion to at least one power harness which is coupled to the electrical power source and in that the pivot comprises a main bore in which are housed on the one hand the connection box so as to be integral in rotation with the pivot and on the other hand the second portion extending the first portion of the heating element.

[0012] Thus, this solution achieves the aforementioned objective. The arrangement of the connection box connecting the second portion to a power supply source for the heating element reduces the size and the interactions of these with the pitch change system. This integration of at least part of the electrical connections inside the pivot of the variable-pitch stator blade is a simple and inexpensive solution. Assembly and disassembly are also simpler because there is no repeated bending of the second portion of the heating element to install the stator blade in the turbomachine casing and to connect the stator blade to the pitch change system. Installing the second portion of the heating element in the bore of the pivot makes it possible to reduce its length, which allows a saving in mass and manufacturing costs.The heating element's lifespan and reliability are improved, as are those of the electrical connection device. In addition, the entire heating element is located within the stator blade, which means that heat loss is reduced to zero.

[0013] The turbomachine assembly also includes one or more of the following features and / or steps, taken alone or in combination: - the pitch change system comprises a control ring and at least one lever which is secured to a radially external end of the pivot by means of at least one fixing member and which is connected to the control ring, the control ring being intended to be moved in rotation around the longitudinal axis and to cause the change in the pitch of the stator blades. - the power harness extends at least partly into the main bore and passes through an orifice of the lever, the power harness having a cross-section equal to at least twice a maximum cross-section of the second portion of the heating element. - the heating element is a heating wire and the second portion of the heating element comprises the heating wire covered with an electrically conductive material. - the pivot comprises a bore extending along an axis parallel to the axis of the main bore, the fixing member comprising a threaded rod extending at least partly into the bore and a threaded sleeve secured to an internal face of the bore. - the pivot comprises an annular groove centered on the wedging axis in which is engaged a retention ring which is also in radial abutment against the internal face of the lever orifice. - filling material occupies a portion of the main bore extending radially below the connection housing and into which the second portion of the heating element extends. - the lever comprises a groove passing through its wall on either side radially at its first end and which is intended to open into the orifice (36) and to be crossed by the supply harness. - the assembly comprises a plurality of variable-pitch stator vanes arranged around the longitudinal axis, each of the pivots being connected to the control ring and in that the connection device comprises several connection boxes each electrically connecting a second portion of a heating element and to the two power harnesses, each power harness being connected to another power harness of one of the connection boxes via a connector. - the first portion and the second portion of the heating element are fully integrated into the stator blade. - each connection box is cylindrical in shape and includes an outer casing protecting a fastener between the second portion of the heating element and one of the power harnesses, the filler material filling the interior of the casing and protecting the power harness portions, heating elements and the fastener. - - the main bore extending coaxially with the pitch axis of the stator blades. - - the main bore extending inclined relative to the radial axis. - - the main bore extending parallel to the timing axis. - - the main bore opens at the radially external end of the pivot and is arranged opposite the through hole provided at the second end of the lever. - - the second portion of the heating assembly is fully housed in the main bore of the pivot.

[0014] 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

[0015] 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: - Figure 1 is a perspective view of a stator blade connected to a pitch change system and equipped with de-icing means according to the invention; - Figure 2 is a perspective and transparent view of an exemplary embodiment of a variable-pitch stator blade connected to a pitch change system and equipped with de-icing means according to the invention; - Figure 3 is a cross-sectional view of an example of a member of a pitch change system according to the invention; - Figure 4 illustrates in perspective an example of a variable-pitch stator blade stage according to the invention; - Figure 5 is a perspective, partial and detailed view of a member of an electrical connection device of the icing means equipping at least one stator blade according to the invention. Detailed description of the invention

[0016] Figure 2 represents an assembly for a turbomachine 1 with longitudinal axis X. The turbomachine is intended to be mounted on an aircraft and may be a turboshaft engine, a turbojet, a turbofan, or even comprise moving fan blades or moving blades of at least one propeller which are shrouded or unshrouded.

[0017] The turbomachine assembly 1 comprises at least one variable-pitch stator blade 2 which is connected to a pitch change system 3. In the present example, several stator blades 2 are distributed around the longitudinal axis X. The pitch change system 3 is configured to change the pitch of at least one stator blade 2 depending on the operating mode of the turbomachine.

[0018] 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 rotor or moving blade of the turbomachine. The stator blades and the rotor 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 rotor blades along the longitudinal axis X.

[0019] In the present invention, and generally, the terms "upstream" and "downstream" are defined in relation 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 in relation to the longitudinal axis X. The terms "external", "external", "internal", "internal" and "radial" are defined in relation to a radial axis Z which extends from the longitudinal axis X and with regard to the distance from the longitudinal axis X. The radial axis is perpendicular to the longitudinal axis X.

[0020] In this embodiment, the variable-pitch stator vanes 2 are preferably mounted in a compressor (not shown) or compressor assembly of the turbomachine and are known as a "rectifier" or by the English acronym "VSV" for "Variable Stator Vane". The stator vanes 2 make it possible to straighten the air flow passing through them.

[0021] Referring to Figure 1, each stator blade 2 comprises a blade 4 which extends radially. Each blade 4 comprises a leading edge 4a and a trailing edge 4b ​​which are connected by an extrados surface 4e (see Figure 3) and a intrados surface 4i.

[0022] Each stator blade 2 comprises a pivot 5 which extends radially from an end 4c of the blade 4. The pivot 5 is mounted to pivot about a setting axis A. The setting axis A extends substantially parallel to the radial axis Z. The setting axis A may have an inclination relative to the radial axis Z.

[0023] The blade 4 and the pivot 5 are connected by a plate 6 which may be optional. Advantageously, the pivot 5 is mounted in a corresponding housing 7 of an external casing 8 (shown in FIG. 2) of the turbomachine. The external casing 8 is advantageously centered on the longitudinal axis X. The casing may be formed of at least two sectors around the longitudinal axis (cut along the plane XZ and assembled for example by longitudinal bolted connections) or be formed of a single annular part. The plate 6 here has a circular shape and is intended to be housed in a recess (not shown) of the external casing 8 so that its internal surface is flush with an internal surface of the external casing 8. However, the plate 8 could have another shape which does not hinder the rotation of the blade and its arrangement relative to the external casing 8.

[0024] Advantageously, each pivot 5 is connected to a control ring 10 via a lever 11. The lever 11 and the control ring 10 are part of the pitch change system 3. The control ring 10 is intended to be moved in rotation around the longitudinal axis X and to cause the pitch of the stator blades 2 to change. The rotation of the control ring 10 is controlled for example by a control means (not shown) of the pitch change system 3. The control means is optionally an actuator. In the present exemplary embodiment, there is at least one lever 11 for each stator blade 2 and a single control ring 10 for all of the stator blades 2.

[0025] Each lever 11 extends between a first end 11a and a second end 11b. The first end 11a is secured to a radially external end 5a (free end) of a pivot 5. For this purpose, the fixing is achieved by means of at least one fixing member 14. Each fixing member 14 comprises, for example, a threaded rod 15 cooperating with a thread 16 arranged at the radially external end 5a. The thread 16 may be carried by a threaded sleeve 17. The first end 11a is pierced with a first hole 18 passing radially through the wall of the lever 11 on either side and which is crossed by the threaded rod 15. Advantageously, the latter extends radially. The second end 11b is secured to the control ring 10.

[0026] The control ring 10 is centered on the longitudinal axis X. The control ring 10 comprises, for example, several radial orifices 19 or notches (visible in FIGS. 2 and 3) which are each intended to cooperate with fixing elements 20. The second end 11 b of each lever 11 is also pierced with a second hole 21 cooperating with the fixing elements 20. The fixing elements 20 comprise, for example, a cylindrical pin 22 which passes through both the second hole 21 and the corresponding radial orifice 19. Each lever 11 is capable of pivoting around the axis of the cylindrical pin 22.

[0027] Each stator blade 2 is equipped with defrosting means 25 for defrosting and / or preventing the formation of frost. The defrosting means 25 comprise in the present example at least one heating element 26, preferably electric.

[0028] With reference to Figure 3, each heating element 26 advantageously comprises a first portion 26a which is mounted within the blade 4. The blade 4 may comprise an internal cavity 27 which extends radially and in which the first portion 26a of the heating element 26 is housed. The latter advantageously extends over the entire radial height of the blade 4 so as to heat the entire blade 4. According to an exemplary embodiment, the internal cavity 27 has a serpentine or trombone shape in which the first portion 26a is arranged. An electric current flowing in the first portion 26a makes it possible to raise the temperature in the blade 4, which makes it possible to prevent the formation of frost. The first portion 26a has a transverse thickness of, for example, between 0.1 m and 10 mm. The first portion 26a is in the form of a heating wire.

[0029] Each heating element 26 comprises a second portion 26b which extends at least partly outside the blade 4. Advantageously, the second portion 26b is an extension of the first portion 26a. The second portion 26b is advantageously, but not limited to, coated with an electrically conductive material 28 so as to efficiently transmit the heat generated in this second portion 26b of the heating element 26 and to avoid a rise in temperature. The electrically conductive material 28 is arranged so as to increase the diameter or cross-section of the heating element 26 from the junction with the first portion 26a to an opposite end 26ba of the second portion 26b. Each second portion 26b is considered to be the cold part of the heating element 26 and each first portion 26a is considered to be the hot part of the heating element 26.

[0030] For example, the maximum diameter of the second portion 26b (with the coating) may be between 0.3 mm and 10 mm, preferably 3 mm. We understand that the diameter of the second portion 26b (with the coating) is greater than that of the first portion 26a. The electrically conductive material 28 may be magnesia. The latter is in the form of a powder which is compacted and applied to form the electrically conductive material and the insulation of the heating element.

[0031] The heating element 26 is connected to an electrical connection device 29. In particular, the electrical connection device 29 comprises an electrical power source 30 which may be a battery or an electrical machine or an alternator (which operates thanks to the turbomachine). The electrical connection device 29 comprises at least one connection box 31 configured to protect the attachment between the second portion and a power harness described below. The attachment may be achieved by welding for example. In the present example, each second portion 26b is coupled to a connection box 31 which connects it to the electrical power source 30. In other words, there are as many connection boxes 31 as there are stator blades 2. The connection boxes 31 are located outside the stator blades 2.According to an optional arrangement, the second portion 26b of the heating element 26 (in particular its end) is shrunk onto the connection housing 31.

[0032] Advantageously, each connection box 31 is a single piece, which makes it easier to mount in the pivot 5 and makes the flow of the electric current more reliable.

[0033] According to an exemplary embodiment, each connection box 31 is cylindrical in shape, preferably straight, and comprises an outer casing made for example from a metallic material. The casing protects the attachment between the heating element 26 and the power cables or harnesses. The connection box connection includes a filler material, for example magnesia (which is in compacted powder form) which fills the interior of the casing and protects the cable portions, heating elements and the fixing. The filler material may include resin disposed at the ends of each connection housing 31.

[0034] Each connection box 31 is coupled to at least one power harness 32a, 32b in which the electric current flows. The harness is for this purpose coupled to the power source 30. Preferably, there are two power harnesses 32a, 32b which each comprise a first end 32aa coupled to the second end 26ba of the second portion 26b of a heating element 26 in the same connection box 31. Each power harness 32a, 32b has a cross-section which is greater than a cross-section of the heating element 26, and in particular of the second portion 26b. The harnesses are “folded” on longer radii. Indeed, each power harness 32a, 32b comprises a protective sheath which provides rigidity to the harnesses. Indeed, each harness comprises for example within it a conductive element enveloped by metal layers which form the protective sheath.The metal layers act as a mechanical reinforcement (prevents the conductor in the center from being overstressed) and as a shield against electrical discharges (current leakage). For example, the diameter or cross-section of the power harness is at least twice the diameter of the maximum diameter of the heating element.

[0035] Each pivot 5 comprises a main bore 33 which extends radially inside it. In the present example, each main bore 33 comprises an axis coaxial with the setting axis A of the blade. Alternatively, the axis of each main bore 33 may be inclined relative to the setting axis A or even be parallel to the setting axis A. The configuration of the main bore will depend for example on several design elements and / or the attachment of the pitch change system. Advantageously, but not limitingly, the main bore 33 opens at the radially external end 5a of each pivot 5. The main bore 33 also opens in this example into the internal cavity 27 formed in the blade 4 which allows the heating element 26 to pass into and outside the blade 4 (in the pivot).

[0036] As can be seen in Figure 1, the or each connection box 31 is housed in a main bore 33 so as to be rotationally integral with the pivot 5. Advantageously, but not limitingly, each connection box 31 is fixed to the internal face 33a of the main bore 33 by means of an adhesive, or a weld. This makes it possible to preserve the physical integrity of the connection box 31 and its electrical connections with the heating element 26 and the or each power harness 32a, 32b. This configuration also makes it possible to reduce the bulk outside the stator blades 2 and the interactions with the pitch change system 3. Each connection box 31 has a complementary shape and matches that of the internal face 33a of the main bore 33. The main bore 33 here has a circular radial section which is not limiting.Advantageously, each connection box 31 has a cylindrical body which extends between a first end 31a and a second end 31b.

[0037] The second portion 26b extending the first portion 26a of the heating element 26 is also housed in the main bore 33. Preferably, and as shown in FIG. 1, the second portion 26b of the heating assembly is entirely housed in the main bore 33 of the pivot. In this way, the first portion 26a and the second portion 26b of a heating element 26 are fully integrated into each stator vane 2, which prevents the heating element 26 from being mechanically stressed when the timing of the stator vane 2 is changed. In addition, the total integration of the heating element 26 in the stator vane 2 improves the heat transfer to the first portion 26a of the heating element 26, which alleviates the limitation imposed on the electrical power of the entire heating element 26.This configuration also further reduces the bulk outside the stator blades 2 and the interactions with the pitch change system 3.

[0038] A filling material 34 is provided to fill a portion 33a of the main bore 33 located radially below the connection housing 31 which does not occupy the main bore 33 in its entirety. Advantageously, the junction of the second portion 26b and the first portion 26a, and the end of the second portion 26b of the heating element 26 which is coupled with the harnesses in the housing connection housing 31 extend into the portion 33a of the main bore 33. In other words, the filling material coats each second portion 26b in the portion 33a of the main bore 33 and comes into contact with the second end of the connection housing 31 and a portion of the inner face of the main bore 33. According to an exemplary embodiment, the filling material 34 is conductive. The filling material may comprise an alumina-filled glue in the form of micro particles. The micro particles form, for example, thermal bridges and greatly improve the conductivity of the glues. In this way, the dissipation of heat to the outside is amplified to its maximum to avoid a rise in temperature of the heating element and the filling material 34 inside the stator blade 2.

[0039] At least a portion of the or each harness 32a, 32b extends at least partly into the main bore 33. The interactions of the or each harness 32a, 32b with the pitch change system 3 are also reduced due to their at least partial integration. The mechanical force during the change of timing of the stator blades 2 is transferred to the harness(es) 32a, 32b which are much more robust than the heating element 26, in particular of the second portion 26b despite its electrically conductive material 28.

[0040] In the present example and in Figure 1, each pivot 5 also comprises a bore 35 which has an axis B parallel to the axis of the main bore 33. In other words, the bore 35 is offset relative to the main bore 33. Each bore 35 is blind and opens at the radially external end 5a of the pivot 5. The threaded rod 15 of each fixing member 14 extends into the bore 35. Furthermore, each threaded sleeve 17 which is intended to be screwed onto the threaded rod 15 is crimped to the internal face 35a of the bore 35. The threaded rod 15 extends at least partly into the bore 35 as well as the threaded sleeve 17. The offset of the fixing of each lever 11 to a pivot 5 allows the main bore 33 to be put in place and the connection box 31 to be installed in the pivot 5.

[0041] Each lever 11 further comprises an orifice 36 which passes through the wall of the lever 11 on either side radially. The orifice 36 is intended to be positioned opposite the main bore 33. The or each harness 32a, 32b extends through the orifice 36.

[0042] Advantageously, each lever 11 advantageously comprises, but not limited to, a recess 37 which opens onto an internal surface 23 of the lever 11. The first hole 18 and the orifice 36 open for example into this recess 37. In other words, the recess 37 is located at the first end 11a of each lever 11. Each recess 37 forms a stop surface 38 against which the edge 39 of the radially external end 5a of the pivot 5 abuts. Each radially external end 5a of the pivot 5 is housed and surrounded at least in part by the recess 37. This allows better centering, positioning precision, and holding in position of the pivots on the levers 11.

[0043] Figure 2 illustrates another embodiment of the connection between the pitch change system 3 and each pivot 5. This embodiment differs from that of Figure 1 in that it is devoid of a bolted connection and the first hole 18. In particular, each fixing member 14 here comprises a retention ring 40, such as a circlip, engaged in an annular groove 41 of a pivot 5. The annular groove 41 is centered on the setting axis A of the pivot 5 and opens onto the external surface 5c of the pivot 5. Advantageously, the retention ring 40 comes into radial abutment against the internal face 36a of the orifice 36 of each lever 11. This configuration makes it possible to secure each pivot 5 in rotation to a lever 11. Furthermore, the retention ring 40 makes it possible to limit the radial size of the pivot and / or of the first end 11a of the lever.

[0044] Each fixing member 14 also comprises a bearing surface 42 carried by the pivot 5 and intended to be a plane bearing connection with the stop surface 38 of the lever 11. In the present example, each pivot 5 comprises a shoulder 43 which defines the bearing surface 42 which is also defined in a plane perpendicular to the wedging axis A. The shoulder 43 also defines a change in section of the pivot 5 at its radially external end 5a. In this way, each pivot 5 comprises for example a first part 44a having a first diameter and a second part 44b having a second diameter different (preferably smaller) from the first diameter. The annular groove 41 is hollowed out in the wall of the second part 44b. The bearing surface 42 bears against the stop surface 38 when the lever 11 and the pivot are fixed. 5. In this embodiment, only the orifice 36 opens into the recess 37. This configuration makes it possible to hold the lever 11 in place on the pivot 5.

[0045] Figure 3 illustrates in more detail stator blades 2 arranged around the longitudinal axis X and which extend radially from an annular shroud 45 preferably centered on the longitudinal axis X. The outer casing 8 (not shown in this figure) radially opposite the annular shroud 45 comprises the housings receiving the pivots 5 of the stator blades 2.

[0046] The pivots 5 can each be mounted in a cylindrical sleeve 46. For this, each cylindrical sleeve 46 comprises a bore 47 (visible in FIG. 1) which is coaxial with the wedging axis A in the installation situation. Each pivot 5 passes through the corresponding bore 47. Advantageously, but not limitingly, there is a clearance between the external diameter of the pivot and the internal diameter of the sleeve. In the example shown, each cylindrical sleeve 46 is formed of two parts. Of course, each cylindrical sleeve 46 can be formed in a single piece. Each sleeve part extends between a first end 48a and a second end 48b. Each part comprises a collar 49a, 49b which extends radially outward from one of the first and second ends. Each cylindrical sleeve 46 is also mounted in the housing of the external casing 8.In this way, the collar 49a of the first part rests on an external surface of the wall of the external casing while the collar 49b of the second part rests on an external surface (opposite the internal surface) of the plate 6. As a variant, the sockets 46 are without a collar.

[0047] As stated previously and illustrated in Figures 3 and 4, there are two harnesses 32a, 32b that are electrically connected to a connection box 31 housed in each pivot 5 of a stator blade. Each pair of harnesses 32a, 32b extends outwardly from the stator blade 2 through the orifice 36 of the lever 11. Each harness is also connected to another harness of one of the other connection boxes 31 via a connector 50. In particular, the second end of a first harness 32a1 coupled to a first connection box 31 is coupled to a first connector 501. The second end of a second harness 32b1 coupled to a second connection box is coupled to the same first connector 501. A third harness coupled to the second connection box is connected to a second connector coupled to the fourth harness coupled to a third connection box, and so on. The harnesses of two adjacent stator blades 2 are connected by a connector. However, adjacent stator blades 2 are not necessarily connected to each other. Generally, stator blades are connected to each other in series or in a loop. By connecting the stator blades in series (e.g., stator blade i connected to stator blade i+3 ), and in the event of a failure on one of the loops, the formation of ice mass on a significant part of the stator blade grid 2 is avoided. Each failed / "non-anti-iced" stator blade 2 will be surrounded by two "anti-iced (with the heating elements working)" stator blades.

[0048] According to one embodiment, each connector 50 comprises a male part and a female part which comprise complementary coupling means.

[0049] According to the embodiment of Figure 4, each connector 50 is a single piece. The harnesses are connected to each of its ends 50a, 50b.

[0050] Figure 5 illustrates an embodiment of a lever 11. The lever 11 comprises a groove 55 which passes transversely through the wall of the lever 11 on either side. Each groove 55 opens on the one hand onto a peripheral lateral surface 56 of the lever 11 and into the orifice 36. In other words, each groove 55 is provided at the first end of the lever 11. The groove 55 also opens onto the internal surface and an external surface 24 opposite along the radial axis. Such a groove 55 makes it easier to insert the harnesses through the orifice 36 when mounting the assembly.

[0051] In this way, the integration of the majority of the connections (heating element and connection box) in a bore 33 hollowed out inside the pivots 5 makes it possible to greatly limit the stresses in the heating element 26 which is integral with the stator blade 2 during its rotational movement. There is a better thermal junction in the heating element 26 and the size of the connections with respect to the pitch change system is reduced. The assembly is more easily mounted and dismounted on the casing.

Claims

Claims [1] Longitudinal axis (X) turbomachine assembly, in particular for an aircraft, comprising: - a variable-pitch stator vane (2) comprising a blade (4) and a pivot (5) extending radially from one end (4c) of the blade (4), - a pitch change system (3) configured to change the timing of the stator blade (2) around its timing axis (A), the pivot (5) being connected to the pitch change system (3), and - a heating element (26) comprising a first portion (26a) mounted within the blade (4) and a second portion (26b) connected to an electrical power source (30) of an electrical connection device (29), characterized in that the electrical connection device (29) comprises a connection box (31) connecting the second portion (26b) to at least one power harness (32a, 32b) which is coupled to the electrical power source (30) and in that the pivot (5) comprises a main bore (33) in which are housed on the one hand the connection box (31) so as to be integral in rotation with the pivot (5) and on the other hand the second portion (26b) extending the first portion (26a) of the heating element (26). [2] Assembly according to claim 1, characterized in that the pitch change system (3) comprises a control ring (10) and at least one lever (11) which is secured to a radially external end (5a) of the pivot (5) by means of at least one fixing member (14) and which is connected to the control ring (10), the control ring (10) being intended to be moved in rotation around the longitudinal axis X and to cause the change in the pitch of the stator blades (2). [3] Assembly according to the preceding claim, characterized in that the power harness (32a, 32b) extends at least partly in the main bore (33) and passes through an orifice (36) of the lever (11), the power harness (32a, 32b) having a cross-section equal to at least twice a maximum cross-section of the second part (26b) of the heating element (26). [4] Assembly according to one of the preceding claims, characterized in that the heating element (26) is a heating wire and the second portion (26b) of the heating element comprises the heating wire covered with an electrically conductive material (28). [5] Assembly according to one of claims 2 to 4, characterized in that the pivot [5] comprises a bore (35) extending along an axis parallel to the axis of the main bore (33), the fixing member (14) comprising a threaded rod (15) extending at least partly in the bore (35) and a threaded sleeve (17) secured to an internal face (35a) of the bore (35). [6] Assembly according to one of claims 3 to 4, characterized in that the pivot (5) comprises an annular groove (41) centered on the wedging axis (A) in which is engaged a retention ring (40) which is also in radial abutment against the internal face (36a) of the orifice (36) of the lever (11). [7] Assembly according to any one of the preceding claims, characterized in that a filling material (34) occupies a portion (33a) of the main bore (33) extending radially below the connection housing (31) and in which the second portion (26b) of the heating element (26) extends. [8] Assembly according to any one of claims 3 to 7, characterized in that the lever (11) comprises a groove (55) passing through its wall on either side radially at the level of its first end (11 a) and which is intended to open into the orifice (36) and to be passed through by the supply harness (32a, 32b). [9] Assembly according to any one of the preceding claims, characterized in that it comprises a plurality of stator vanes (2) with variable pitch arranged around the longitudinal axis (X), each of the pivots (5) being connected to the control ring (10) and in that the connection device (29) comprising several connection boxes (31) each electrically connecting a second portion (26b) of a heating element (26) and to the two power supply harnesses (32a, 32b), each power supply harness being connected to another power supply harness of one of the connection boxes (31) via a connector (50). [10] Assembly according to any one of the preceding claims, characterized in that the first portion (26a) and the second portion (26b) of the heating element (26) are fully integrated into the stator vane (2). [11] An assembly according to any one of claims 7 to 10, characterized in that each connection box (31) is cylindrical in shape and comprises an outer casing protecting a fixing between the second portion (26b) of the heating element (26) and one of the power harnesses (32a, 32b), the filling material filling the interior of the casing and protecting the power harness portions, heating elements and the fixing. [12] Turbomachine (1) comprising an assembly according to any one of the preceding claims.

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