TURBOMACH ASSEMBLY COMPLIMENTING WITH AN ADJUSTABLE STATOR BLADE EQUIPPED WITH A HEATING ELEMENT, AND TURBOMACH

Description

Technical field of the invention

[0001] The present invention relates to the aeronautical field, particularly aircraft propulsion. It specifically concerns a turbomachine assembly comprising a variable-pitch stator blade equipped with a heating element. Technological background

[0002] Many turbomachines, such as turbojets and turboprops, are equipped with variable-pitch stator blades. These variable-pitch stator blades are arranged around the turbomachine's longitudinal axis and are generally positioned upstream or downstream of rotor blades, following the gas flow within the turbomachine, to direct the airflow towards or from the rotor blades at the correct angle. Their pitch allows them to adapt to various turbomachine operating conditions. To achieve this, the variable-pitch stator blades are connected to a pitch control system configured to vary their pitch or inclination around their pitch axis during flight.

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

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

[0005] The power cables have extra length to accommodate the rotation of the stator blades during pitch changes, but this can interfere with the pitch change system. The electrical connection device can also move during stator blade rotation. Spacers have been considered to prevent these interactions; however, this results in significant bulk in an area already constrained by available space. Despite this, mechanical stress and deformation of the power cables between the heating elements in the moving position and the electrical connection device in the fixed position are unavoidable. 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 limited space. The assembly of the pitch control system and the adjustment of the stator blade pitch involve several tightening and / or loosening operations, which put stress on the power cables, potentially affecting their mechanical strength, as well as on the electrical connectors, the connection between the heating element and the electrical connection device, and the heating element itself. The heating elements have an insulating sheath along part of their length, which is rigid, fragile, and susceptible to repeated or extreme mechanical stresses that can cause them to break.The heating element power cables typically include electrical insulation that is more flexible and offers better resistance to repeated stress than the heating elements themselves. Installation is also complex, as the power cables must pass through the respective bushings and housings in the turbomachine casing before the pivots are engaged in their slots.

[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 exposed parts is a limiting factor for the electrical power flowing through the power cables and reduces the power density that can be integrated.

[0008] Document GB-A-2403778 describes a turbomachine comprising variable-pitch stator blades equipped with heating elements. The heating elements comprise a first section integrated into the blade and a second, connected section of considerable length extending through passages formed in the blade. These passages are arranged radially below the blade pivot. The second section of the heating element passes through a junction box housed in the blade pivot and extends outside the blade to a power source. The arrangement of this heating element is complex due to the excess length that must be handled and positioned within the various passages and cavities. The second section of the heating element is also subject to various mechanical stresses during stator blade pitch adjustment.

[0009] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0010] The objective of the present invention is to provide a simple, robust and economical solution to reduce or even eliminate the mechanical stresses on the power supply means of the heating means of a variable pitch stator blade in order to avoid the formation of frost, while allowing the latter to be pitched.

[0011] We achieve this objective in accordance with the invention by means of a longitudinally axis turbomachine assembly, in particular for aircraft, comprising: a variable-pitch stator blade comprising a blade and a pivot extending radially from one end of the blade, the pivot comprising a main bore, a pitch-changing system configured to change the pitch of the stator blade about its pitch axis, and a heating element comprising a first portion mounted within the blade and a second portion, extending outside the blade, connected to an electrical connection device, the pivot comprising a bore which passes through the wall of the pivot so as to open on one side into the main bore and on the other side into an external surface of the pivot, and a radial groove formed in the wall of the pivot which opens onto the external surface and into an outlet of the bore, the second portion extending from the first portion and the second portion extending into the main bore, into the bore and then into the radial groove towards the electrical connection device.

[0012] Thus, this solution achieves the aforementioned objective. Positioning part of the second section both inside and outside the pivot reduces its length and minimizes interactions with the pitch control system. Mechanical stresses are transferred to other, more robust components of the electrical connection device. Reducing the length of the second section also results in weight savings and lower manufacturing costs. The overall dimensions are further improved, as the second section outside the pivot is positioned as close as possible to the pivot diameter by being mounted in the groove. Assembly and disassembly are also simpler, as there are no repeated bends required for the shorter second section of the heating element to install the stator blade in the turbomachine housing and to connect the stator blade to the pitch control system.The lifespan and reliability of the heating element are improved, as are those of the electrical connection device. The central drilling and bore configuration is a simple and cost-effective solution. Furthermore, the connection between the stator blade pivot and the pitch change system can be simplified yet remains robust, thus ensuring reliable blade pitch adjustment.

[0013] The turbomachine assembly also includes one or more of the following features, taken alone or in combination with each other: The electrical connection device comprises at least one connection box and at least one harness coupled to the first portion of the heating element via the connection box and to a power supply, the harness extending outside the pivot. The pitch change system comprises a control ring and at least one lever secured to a radially external end of the pivot by means of at least one fastener and connected to the control ring, which is intended to be rotated about the longitudinal axis and to change the stator vane pitch. The assembly includes a support member rotatably fixed to the lever and configured to carry and retain the connection box. The support member is fixed to the lever with the same fastener.The lever includes a groove running radially through its wall on both sides at its first end, designed to receive at least part of the second portion of the heating element. The assembly includes a cylindrical sleeve with a bore for the pivot to pass through, the second portion of the heating element running radially above the cylindrical sleeve. The assembly includes a cylindrical sleeve with a bore for the pivot to pass through, the second portion of the heating element running between the cylindrical sleeve and the pivot.The assembly comprises a plurality of variable-pitch stator blades arranged around the longitudinal axis, each pivot being connected to the control ring, and the connection device comprising several junction boxes, each electrically connecting a second portion of a heating element and at least two harnesses, each harness being connected to another harness of one of the junction boxes via a connector. - - The main bore extending coaxially to the pitch axis of the stator blades. - - The main bore extending inclined with respect to the radial axis. - - The main bore extending parallel to the pitch axis.

[0014] The invention relates to a turbomachine, in particular for 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 objects, details, features and advantages thereof will become more apparent upon reading the detailed explanatory description that follows, of embodiments of the invention given by way of purely illustrative and non-limiting examples, with reference to the accompanying schematic drawings in which: There figure 1 is a partial perspective view of an annular row of variable-pitch stator blades according to the invention; The figure 2 is a perspective view of stator blades connected to a pitch-changing system and equipped with de-icing means according to the invention; The figure 3 is an axial cross-sectional view of an example of a variable-pitch stator blade equipped with de-icing means according to the invention; The figure 4 is a cross-sectional view of another embodiment of a stator blade equipped with de-icing means according to the invention; The figure 5illustrates an example of the realization of a linking element between a variable-pitch stator blade and a control element according to the invention. Detailed description of the invention

[0016] There figure 1 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 turboengine, a turbojet, a turbofan, or include movable fan blades or movable blades of at least one propeller, whether shrouded or unshrouded.

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

[0018] In the present invention, the term "stator blade" or "fixed blade" refers to 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 unlike a rotor or moving blade of the turbomachine. Stator blades and rotor blades are generally arranged in annular rows, and the annular rows of stator blades are positioned 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 with respect to the flow of gases or air within the turbomachine, specifically along the longitudinal axis X. The terms "axial" and "axially" are defined with respect to the longitudinal axis X. The terms "external," "outer," "internal," "internal," and "radial" are defined with respect to a radial axis Z extending 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.

[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 "straightener" or by the English acronym "VSV" for "Variable Stator Vane". The stator vanes 2 allow the airflow passing through them to be straightened.

[0021] With reference to the figure 2 , 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 and an intrados surface 4i (cf. figure 1 ).

[0022] Each stator blade 2 includes a pivot 5 extending radially from one end 4c of the blade 4. The pivot 5 is mounted to pivot about a shim axis A. The shim axis A extends substantially parallel to the radial axis Z. The shim axis A may be inclined with respect 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 in an external casing 8 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 XZ plane and assembled, for example, by longitudinal bolted connections) or be formed of a single annular piece. The plate 6 has a circular shape and is designed to be housed in a recess 9 (visible on the figure 3 ) of the outer casing 8 so that its internal surface 6a is flush with an internal surface 8a of the outer casing 8. However, the plate 8 could have another shape which does not hinder the rotation of the blade and its arrangement with respect to the outer 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 form part of the pitch-changing system 3. The control ring 10 is designed to rotate about the longitudinal axis X and to change the pitch of the stator vanes 2. The rotation of the control ring 10 is controlled, for example, by a control means (not shown) of the pitch-changing system 3. The control means is optionally an actuator. In this embodiment, there is at least one lever 11 for each stator vane 2 and a single control ring 10 for all the stator vanes 2.

[0025] Each lever 11 extends between a first end 11a and a second end 11b. The first end 11a is fixed 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 supported by a threaded bushing 17. The first end 11a of each lever 11 is drilled, for example, with a first hole 18 passing radially through the wall of the lever 11 and through which the threaded rod 15 passes. The second end 11b is fixed to the control ring 10.

[0026] The control ring 10 is centered on the longitudinal axis X. The control ring 10 includes, for example, several radial holes 19, each intended to cooperate with fastening elements 20. The second end 11b of each lever 11 also has a second hole 21 that cooperates with the fastening elements 20. The fastening elements 20 include, for example, a cylindrical pin 22 that passes through both the second hole 21 and the corresponding radial hole 19. Each lever 11 is able to pivot about the axis of the cylindrical pin 22.

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

[0028] With reference to the figure 3Each heating element 26 advantageously comprises a first portion 26a mounted within the blade 4. The blade 4 may include an internal cavity 27 extending radially, in which the first portion 26a is housed. This first portion 26a advantageously extends along the entire radial height of the blade 4 so as to heat the entire blade 4. In one embodiment, the internal cavity 27 has a serpentine or paperclip shape in which the first portion 26a is arranged. An electric current flowing through the second portion 26b raises the temperature in the blade 4, thus preventing frost formation. The first portion 26a has a transverse thickness, for example, between 0.1 mm and 10 mm. The first portion 26a is shaped like a heating wire.

[0029] Each heating element 26 comprises a second portion 26b that extends at least partially 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 exclusively, 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 prevent a temperature rise. The electrically conductive material 28 is arranged such 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 diameter of the second portion 26b can be between 0.3 mm and 10 mm, preferably 3 mm. The electrically conductive material 28 can be magnesia. This 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 connection device 29 includes a power supply 30, which can be a battery, an electric machine, or an alternator (powered by the turbomachine). The connection power supply device 29 includes at least one connection box 31 configured to protect the connection between the second portion and a power harness described below. The connection can be made by welding, for example. In this example, each second portion 26b is coupled to a connection box 31. 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 each heating element 26 (in particular its end) is shrink-fitted onto the connection box 21.

[0032] According to one embodiment, each connection box 31 is cylindrical, preferably straight, and comprises an outer casing made, for example, of a metallic material. The casing protects the connection between the heating element 26 and the power cables or harnesses. The connection box 31 includes a filling material, for example, magnesium oxide (which is in the form of compacted powder), which fills the interior of the casing and protects the cable, heating element, and connection portions. The filling material may include resin located at the ends of each connection box 31.

[0033] Each connection box 31 is coupled to at least one harness 32a, 32b through which the electric current flows. The harness is connected to the power supply 30 for this purpose. Preferably, there are two power harnesses 32a, 32b, each comprising a first end 32aa coupled to the second end 26ba of the second portion 26b of a heating element 26 within the same connection box 31. Each power harness 32a, 32b has a cross-section that is greater than the cross-section of the heating element 26, and in particular of the second portion 26b. The harnesses are folded along longer radii. Each power harness 32a, 32b includes a protective sheath that provides rigidity to the harnesses. Each harness, for example, includes a conductive element surrounded by metallic layers that form the protective sheath.The metallic layers act as mechanical reinforcement (preventing excessive stress on the central conductor) and as shielding against electrical discharges (current leakage). For example, the diameter or cross-section of each power harness 32a, 32b is at least twice the maximum diameter of the heating element.

[0034] On the Figures 1 And 2Each pair of harnesses 32a, 32b extends outside the stator blade 2. Each harness 32a, 32b is also connected to another harness from 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 311 is mated to a first connector 501. The second end of a second harness 32b1 coupled to a second connection box 312 is mated to the same first connector 501. A third harness 32a2 coupled to the second connection box 312 is connected to a second connector 502 mated to a 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. In general, stator blades are connected to each other in series or in a loop.By connecting the stator blades in series (for example, 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 on a significant portion of the stator blade grid 2 is prevented. Each failed / "non-anti-icing" stator blade 2 will be surrounded by two "anti-icing" stator blades (with the heating elements functioning).

[0035] Advantageously, each 50 connector comprises a male and a female part, each of which includes complementary mating means. Alternatively, each 50 connector is a single piece.

[0036] Following an example embodiment, the assembly may include a support ring 43 (visible on the figure 1) which is intended to support the connector(s) 50 and the power harnesses 32a, 32b. The support ring 43 can be centered on the longitudinal axis. It is made in one piece, but could be segmented.

[0037] Each pivot 5 includes a main bore 33 extending radially within it. In this example, each main bore 33 has an axis coaxial with the blade's pitch axis A. Alternatively, the axis of each main bore 33 may be inclined relative to the pitch axis A or parallel to it. The configuration of the main bore will depend, for example, on various design elements and / or the mounting of the pitch-change system. Advantageously, but not exclusively, the main bore 33 opens at the radially external end 5a of each pivot 5. The main bore 33 here has a circular radial cross-section, which is not a limiting factor. The main bore 33 also opens in this example into the internal cavity 27 provided in the blade 4, which allows the path of the heating element 26 in and out of the blade 4.

[0038] In this example, each threaded sleeve 17 is intended to be screwed onto the threaded rod 15 and is crimped to the inner face 33a of the main bore 33. The threaded rod 15 extends at least partially into the main bore 33, as does the threaded sleeve 17.

[0039] As illustrated on the figure 2Each pivot 5 includes a bore 34 that passes through the wall of the pivot 5. Each bore 34 opens, for example, on one side into the main bore 33 and on the other side onto an external surface 5c of the pivot 5. Advantageously, but not exclusively, each bore 34 has an axis that is inclined with respect to the radial axis or the axis of the main bore 33. The angle of inclination is, for example, between 25° and 70° with respect to the radial axis Z. In this way, the second portion 26b of the heating element 26 travels through a part of the main bore 33 and is then oriented towards the bore 34. Upon exiting the bore 34, the second portion 26b is oriented towards the radially external end 5a of the pivot 5. The second portion 26b quickly regains a radial orientation, which helps to limit its radial footprint while respecting the minimum acceptable radius of curvature by the second portion 26b of the heating element 26.This configuration also allows bypassing the fixing member 14 which occupies part of the main bore 33. Furthermore, the routing of at least part of the second portion 26b of the heating element 26 outside the pivot 5 and not in the center of the pivot 5 makes it easier to fix the lever 11 on the radially external end 5a of the pivot 5.

[0040] Each pivot 5 advantageously includes a radial groove 35 which is formed in the wall of the pivot 5. Each radial groove 35 opens onto the external surface 5c of the pivot 5. Each radial groove 35 has a radial cross-section substantially in the shape of a U, C. The radial grooves 35 each open onto an outlet 34b of the holes 34. Advantageously, each radial groove 35 opens onto the radially external end 5a of the pivot 5 and preferably onto an edge 36 of the radially external end. A portion of each second portion 26b is housed and guided in the radial groove 35. The routing of the second portion 26b in the radial groove 35 further reduces the radial space at the pivot 5 and enables the electrical connection of the heating element 26 and the connection box 31 to be made before the mounting of the stator blades 2 on the external housing 8 of the turbomachine.The second portion 26b of the heating element 26 curves horizontally at the radially external end 5a of the pivot 5 with a smaller overhang. This facilitates the attachment of the levers 11 to the pivots 5.

[0041] The pivots 5 can each be mounted in a cylindrical sleeve 37. For this purpose, each cylindrical sleeve 37 includes a bore 38 which is coaxial with the mounting axis A in the installed position. Each pivot 5 passes through the corresponding bore 38. Advantageously, but not exclusively, there is a clearance between the external diameter of the pivot and the internal diameter of the sleeve 37. In the example shown, each cylindrical sleeve 37 is formed of two parts 37a, 37b. Of course, each cylindrical sleeve 37 can be formed in one piece. Each part 37a, 37b extends between a first end 39a and a second end 39b. Each part includes a flange 40a, 40b which extends radially outwards from one of the first and second ends. Each cylindrical sleeve 37 is also mounted in the housing 7 of the outer casing.Thus, the collar 40a of the first part 37a rests on an external surface of the wall of the external housing 8 while the collar 40b of the second part rests on an external surface (opposite to the internal surface) of the plate 6. Alternatively, the sockets 37 are without a collar. The first end 39a of the first part 37a is located at a height that is greater than the height of the outlet of the bore 34. In other words, the outlet of the bore 34 can open inside the cylindrical sleeve part 37. In this way, the second portion 26b of the heating element 26 runs between the sleeve 37 and the pivot 5. Alternatively, the first end 38a of the first part 37a of the cylindrical sleeve 37 is lower than the height of the outlet 34a of the bore 34 so that the outlet of the bore 34 opens above the collar 40a.In this way, the second portion 26b of the heating element 26 runs radially above the socket 37.

[0042] With reference to the figure 3 Each lever 11 advantageously, but not exclusively, comprises a recess 41 that opens onto an internal surface 23 of the lever 11. The first hole 18 opens into this recess 41. In other words, the recess 41 is located at the first end 11a of each lever 11. Each recess 41 forms a stop surface 42 against which the edge 36 of the radially external end 5a of the pivot 5 abuts. Each radially external end 5a of the pivot 5 is housed and at least partially enclosed by the recess 41. This allows for better centering and retention of the pivots in position on the levers 11.

[0043] There figure 4This illustrates another embodiment of the turbomachine assembly. This embodiment differs from the previous one in that a support member 45 is configured to carry and retain the connection housing 31. In this example, each support member 45 is rotationally fixed to one of the levers 11. To this end, each support member 45 is attached to a lever 11 with the same fastening member 14 located at the radially external end 5a of the pivot 5. Each support member 45 comprises, for example, an arm 46, one end 46a of which is fixed to the lever 11. The arm 46 comprises, at a second opposite end 46b, two lateral faces 47 which are positioned opposite each other and spaced apart in the circumferential direction to create a gap. Each connection box 31 rests on the arm 46 and is arranged between the two lateral panels 47.Advantageously, each connection box 31 is fixed to the support 45, for example, by clipping or gluing. The support member 45 keeps the connection box fixed relative to the lever 11. Relative movement between the connection boxes 31 and the heating elements 26 is thus eliminated. This prevents any stress being transferred during operation to the heating elements (first and second sections) or to the connection / fixing between the heating elements and the connection boxes, both of which are fragile.

[0044] In this embodiment, the first end 11a of the lever 11 comprises an external surface 24 radially opposed to the internal surface 23. The external surface 24 is defined in a first plane extending radially above a second plane in which the external surface of the rest of the lever body 11 is defined. Here, the second end 11b extends at a distance and radially below the support member 45. This configuration facilitates the attachment of each lever 11 with the control ring 10.

[0045] On the figure 4 We can also see the second portion 26b of the heating element in dotted line which is not yet connected to the connection box 31 and the second portion 26b connected to the connection box 31. When the second portion is connected it forms a curve and passes over the fixing member 14.

[0046] There figure 5This illustrates an embodiment of a lever 11. The lever 11 includes a groove 55 intended to receive at least part of the second portion 26 of the heating element 26. The groove 55 passes through its wall on both sides along the radial axis. In other words, the groove 55 opens onto both the external surface 24 and the internal surface 23, which are opposite along the radial axis. In this example, the external surface 24 of the lever 11 is defined in the same plane, but could be defined in two different parallel planes. The groove 55 also opens onto a peripheral lateral surface 51 of the lever 11. Advantageously, this latter surface connects the external and internal surfaces 23, 24. Advantageously, the groove 55 is formed at the first end 11a of the lever 11. The groove 55 has a radial cross-section in the shape of a U or a C.Optionally, the groove 55 is aligned or substantially aligned with the groove 35 (the axis of the groove may be parallel to the axis of the groove 55). Positioning the groove 55 on the lever 11 further reduces the overall size of the power supply device, and in particular of the second portion 26b of the heating element 26.

Claims

1. An assembly of a turbine engine having a longitudinal axis (X), 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), the pivot (5) comprising a main bore (33), - a pitch change system (3) configured to change the pitch of the stator vane (2) about its pitch axis (A), and - a heating element (26) comprising a first portion (26a) mounted within the blade (4) and a second portion (26b), extending outside the blade (4), connected to an electrical connection device (29), characterized in that the pivot (5) comprises a drilled hole (34) which passes through the wall of the pivot (5) so as to open, on the one hand, into the main bore (33) and, on the other hand, onto an external surface (5c) of the pivot (5), and a radial groove (35) formed in the wall of the pivot (5) which opens onto the external surface (5c) and into an outlet of the drilled hole (34), the second portion (26b) continuing the first portion (26a) and the second portion (26b) extending into the main bore (33), into the drilled hole (34), and then into the radial groove (35) towards the electrical connection device.

2. The assembly according to the preceding claim, characterized in that the electrical connection device (29) comprises at least one connection box (31) and at least one harness (32a, 32b) which is coupled to the first portion (26a) of the heating element (26) via the connection box (31) and to a source of electrical power supply (30), the harness (32a, 32b) extending outside the pivot (5).

3. The assembly according to one of the preceding claims, characterised 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 of the pivot (5) by means of at least one fastening member (14) and connected to the control ring (10) which is configured to be rotated about the longitudinal axis X and to bring about the change in pitch of the stator vanes (2).

4. The assembly according to the preceding claim, characterised in that it comprises a support member (45) rotationally secured to the lever (11) and which is configured so as to carry and retain the connection box (31).

5. The assembly according to the preceding claim, characterized in that the support member (45) is fixed to the lever (11) with the same fastening member (14).

6. The assembly according to any one of claims 3 to 4, characterised in that the lever (11) comprises a channel (55) passing through its wall on either side radially at its first end (11a) and which is configured to receive at least part of the second portion (26b) of the heating element (26).

7. The assembly according to the preceding claim, characterized in that it comprises a cylindrical socket (37) provided with a bore (38) configured to be passed through by the pivot (5), the second portion (26b) of the heating element (26) running radially above the cylindrical socket (37).

8. The assembly according to claim 6, characterized in that it comprises a cylindrical socket (37) provided with a bore (38) configured to be passed through by the pivot (5), the second portion (26b) of the heating element (26) travelling between the cylindrical socket (37) and the pivot (5).

9. The assembly according to any one of the preceding claims, characterized in that it comprises a plurality of stator vanes (2) with variable pitch arranged about the longitudinal axis (X), each of the pivots (5) being connected to the control ring (10), and in that the connection device (29) comprises several connection boxes (31) each electrically connecting a second portion (26b) of a heating element (26) and at least two harnesses, each harness being connected to another harness of one of the connection boxes (31) via a connector (50).

10. The assembly according to any one of the preceding claims, characterized in that the main bore (33) extends coaxially with the pitch axis of the stator vanes.

11. The assembly according to any one of claims 1 to 10, characterised in that the main bore (33) extends at an angle to the radial axis.

12. The assembly according to any one of claims 1 to 11, characterized in that the main bore (33) extends parallel to the pitch axis.

13. A turbine engine (1) comprising an assembly according to any one of the preceding claims.