TURBOMACHINE KIT INCLUDING A LIGHTNING SENSOR SYSTEM

Abstract

An assembly (1) of variable-pitch blades for an unfaired aircraft turbomachine, the assembly comprising a rotor (3) movable about a radial axis (X) of the turbomachine, a stator (4) fixed about said radial axis (X), and at least one lightning arrester (5). The lightning arrester (5) comprises a pin (6), at least one face of said pin (6) being in contact by friction with the rotor (3), a screw (7) radially extending from said pin (6), and a means (8) for connecting the pin (6) and the screw (7), said means (8) comprising a spring interposed between the pin (6) and the screw (7). Figure for the abbreviation: Fig 1

Description

Title of the invention: TURBOMACHINE ASSEMBLY COMPRISING A LIGHTNING SENSOR SYSTEM technical field

[0001] The invention relates to the dimensioning of a turbomachine in particular for the purpose of managing a lightning strike on a turbomachine.

[0002] The invention relates to a variable-pitch bladed turbomachine comprising a rotor and a stator and in particular to an unshrouded turbomachine in which the rotor includes a blade root rotating relative to the stator.

[0003] The blade of an unfaired turbomachine is susceptible to being struck by the lightning, unlike enclosed turbomachinery which includes a protective nacelle.

[0004] An unshrouded turbomachine must therefore include a lightning recovery system comprising a grounding connection for the recovered current. The lightning recovery system creates a preferential short-circuit path for lightning. This prevents potentially dangerous structural damage to the turbomachine.

[0005] Today, lightning grounding connections for turbomachinery generally include an electrically conductive braid comprising copper or aluminum cables. The braid provides a secure path that rapidly dissipates the electrical current induced by lightning.

[0006] The braid is connected at one end to the turbomachine rotor and at the other end to the turbomachine stator. If lightning strikes the turbomachine blade, the current induced by the lightning is directly transmitted through the braid, which directs it towards the aircraft.

[0007] However, this solution is not optimal because the braid induces significant frictional forces, particularly when the rotor is rotating relative to the turbomachine's stator. Furthermore, the braid is difficult to integrate into a locally congested environment such as the turbomachine's stator / rotor assembly. In addition, the lightning recovery system must include a braid of considerable length so that it can be wound around the rotor while it is in motion.

[0008] The aforementioned disadvantages cause architectural and space problems at the level of the turbine blades of the turbomachine. Description of the invention

[0009] The present invention aims to overcome the aforementioned problems and, in particular, to limit frictional forces and optimize the architecture within the turbomachine.

[0010] The invention therefore relates to a blade assembly, in particular a variable pitch blade for an unfaired turbomachine, the assembly comprising a rotor movable relative to a radial axis of the turbomachine, a stator fixed relative to the radial axis and at least one lightning recovery system.

[0011] The lightning recovery system includes a pin, at least one face of said pin being in contact by friction with the rotor, a screw radially extending said pin and a means of connecting the pin and the screw, said connecting means comprising a spring interposed between the pin and the screw.

[0012] Advantageously, the rotor includes a blade foot and variable pitch blades fixed on the blade foot.

[0013] According to one embodiment, the screw of the lightning recovery system passes through the stator along a longitudinal axis of the turbomachine and in which the pin is in contact with the external lateral surface of the rotor.

[0014] Advantageously, the external lateral surface of the rotor includes a radial groove into which the pin is inserted.

[0015] According to one embodiment, the pawl comprises graphite.

[0016] Advantageously, at least the face of the pin in contact with the rotor has a coating comprising a low coefficient of friction.

[0017] According to one embodiment, the screw includes a thread in which the spring and part of the pin are inserted.

[0018] Advantageously, the face of the pin in contact with the rotor comprises a concave profile conforming to the shape of the rotor.

[0019] According to one embodiment, the assembly comprises two lightning recovery systems distributed radially around the rotor.

[0020] The invention also relates to an unfaired turbomachine comprising an assembly as defined above. Brief description of the drawings

[0021] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0022] - Figure [Fig. 1] is a schematic view of a variable pitch blade assembly including a lightning recovery system;

[0023] - Figure [Fig.2] is a schematic view of a recovery system for the lightning ;

[0024] - Figure [Fig.3] is a schematic top view of a pitched blade assembly variable including a lightning recovery system. Detailed description

[0025] Figure 1 shows a variable-pitch blade assembly of an aircraft turbomachine, the assembly being designated by the numerical reference 1. The assembly is in an orthonormal X, Y, Z frame, in which the X axis designates a radial direction of the turbomachine, the Y axis designates another radial direction of the turbomachine, the Y axis being transverse to the X axis of the turbomachine, and the Z axis designates a longitudinal direction of the turbomachine, which is substantially parallel to a longitudinal direction of the aircraft when the turbomachine is installed on the latter.

[0026] Assembly 1 comprises a main structure, a rotor 3 movable relative to the radial axis X of the turbomachine, a stator 4 fixed relative to the radial axis X of the turbomachine and a lightning recovery system 5.

[0027] The rotor 3 comprises a blade base 3a, variable-pitch blades not shown in the figures fixed to the blade base 3a, and a pivot 3b. The stator 4 surrounds the rotor 3; more particularly, said stator 4 surrounds the pivot 3b of the rotor 3 and is fixed to the main structure of the turbomachine.

[0028] As illustrated in [Fig.2], the lightning recovery system 5 comprises a pin 6, a screw 7 and a means of connecting the pin 6 and the screw 7. At least one face of said pin 6 is in contact by friction with the rotor 3 and the screw 7 is located in the radial extension of said pin 6. The screw 8 passes through the stator 4 along the longitudinal axis Z of the turbomachine.

[0029] According to the embodiment shown in the figures, the pin 6 has substantially a cylindrical shape, one of whose lateral bases is in contact by friction with an external lateral surface of the pivot 3b of the rotor 3. The pin 6 thus extends radially towards the stator 4 the external lateral surface of the pivot 3b of the rotor 3. The pin 6 and the screw 7 form an elongated element in contact with the pivot 3b of the rotor 3 and passing through the stator 4 to an exit point 9. Advantageously, the pin 6 comprises graphite.

[0030] The means for connecting the pin 6 and the screw 7 includes a spring interposed between said pin 6 and said screw 7. More specifically, the screw 7 includes a threaded hole 7a into which the spring and a portion of the pin 6 are inserted. The spring thus connects the screw 7 and the pin 6 and creates a mechanical force compelling the pin 6 to make contact with the rotor 3. The pin 6 is in contact with the screw 7, and more specifically with the threaded hole 7a of the screw 7, in order to facilitate the transmission of current when lightning strikes assembly 1.

[0031] In addition, the external lateral surface of the rotor 3 includes a radial groove 3c in which at least part of the lightning recovery system 5 is inserted, and in particular in which the pin 6 and part of the screw 7 are inserted. The groove 3c of the rotor 3 makes it possible not to locally obstruct the variable pitch blade assembly 1, the lightning recovery system 5 thus being directly embedded in the variable pitch blade assembly 1.

[0032] As illustrated in [Fig.1], the lightning-induced current passes through the blade foot 3a and the pivot 3b of the rotor 3 and is attracted by the graphite pin 6, passes through the spring and the screw 7 and goes to the exit point 9 of the lightning recovery system 5. The exit point 9 of the lightning recovery system 5 then directs the current to the aircraft structure.

[0033] Figure 3 shows a top view of the pivot 3b of the rotor 3 and the pin 6 in contact with the outer lateral surface of said pivot 3b. The face of the pin 6 in contact with said pivot 3b has a concave profile 10. The concave profile 10 of the pin 6 is complementary in shape to the outer lateral surface of the pivot 3b, thus improving the contact between the pin 6 and the pivot 3b. In particular, the concave profile 10 of the pin 6 follows the cylindrical shape of the pivot 3b of the rotor 3.

[0034] This feature also makes it possible to enlarge the contact area between the rotor 3 and the pin 6 and increase the efficiency of the lightning recovery system 5 when the current to be recovered is high. If the current to be recovered is rather low, a simple point contact between the rotor 3 and the pin 6 may suffice.

[0035] At least the face of the pin 6 in contact with the rotor 3 has a coating 11 comprising a low coefficient of friction, preferably between 0.02 micrometers and 0.1 micrometers. Similarly, the outer lateral face of the rotor 3 or the inner face of the groove 3c in contact with the pin 6 comprises a coating comprising a low coefficient of friction.

[0036] Furthermore, the pin 6, the screw 7, and the connecting means 8 for the pin 6 and the screw 7 are capable of withstanding the charge of the recovered lightning current. The pin 6, the screw 7, and the connecting means 8 for the pin 6 and the screw 7 comprise electrically conductive materials.

[0037] Of course, the invention remains within the scope of the invention even if the assembly 1 has a different composition. It is thus possible to design a lightning recovery system 5 comprising several pins 6 and / or several screws 7 and / or several means of connecting the pin 6 and the screw 7. It is also possible to consider that the lightning recovery system 5 is positioned axially between the blade root 3a and the stator 4, the pin 6 thus being in contact by friction with the underside of the blade root 3a. Furthermore, a variable-pitch blade assembly 1 can comprise several lightning recovery systems 5 as described above.

[0038] Finally, a lightning recovery system 5 applies to any system comprising a part rotating with respect to a fixed part, said system being liable to be struck by lightning.

[0039] The lightning recovery system 5 provides electrical continuity between the rotor 3 and the stator 4 of a turbomachine without generating excessive friction in assembly 1. The lightning recovery system 5 is easy to manufacture and install and does not obstruct the turbomachine locally. Furthermore, the lightning recovery system 5 is easily accessible for maintenance on the turbomachine.

Claims

Demands

1. Variable pitch blade assembly (1) for an unfaired aircraft turbomachine, the assembly comprising a rotor (3) movable about a radial axis (X) of the turbomachine, a stator (4) fixed about said radial axis (X) and at least one lightning recovery system (5), characterized in that the lightning recovery system (5) comprises a pin (6), at least one face of said pin (6) being in contact by friction with the rotor (3), a screw (7) radially extending said pin (6) and a means of connecting (8) the pin (6) and the screw (7), said means of connecting (8) comprising a spring interposed between the pin (6) and the screw (7).

2. Assembly (1) according to claim 1, wherein the rotor (3) comprises a blade foot (3a) and variable pitch blades fixed on the blade foot (3a).

3. Assembly (1) according to any one of claims 1 and 2, wherein the screw (7) of the lightning recovery system (5) passes through the stator (4) along a longitudinal axis (Z) of the turbomachine and wherein the pin (6) is in contact with the external lateral surface of the rotor (3).

4. Assembly (1) according to any one of claims 1 to 3, wherein the external lateral surface of the rotor (3) comprises a radial groove (3c) into which the pin (6) is inserted.

5. Assembly (1) according to any one of claims 1 to 4, wherein the pin (6) comprises graphite.

6. Assembly (1) according to any one of claims 1 to 5, wherein at least the face of the pin (6) in contact with the rotor (3) has a coating (11) comprising a low coefficient of friction, preferably between 0.02 micrometer and 0.1 micrometer.

7. Assembly (1) according to any one of claims 1 to 6, wherein the screw (7) comprises a thread (7a) into which the spring and a part of the pin (6) are inserted.

8. Assembly (1) according to any one of claims 1 to 7, wherein the face of the pin (6) in contact with the rotor (3) comprises a concave profile (10) conforming to the shape of the rotor (3).

9. Assembly (1) according to any one of claims 1 to 8, comprising two lightning recovery systems (5) distributed radially around the rotor (3).

10. unfaired turbomachine comprising an assembly (1) according to any one of claims 1 to 9.

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