Anti-free rotation device for an aircraft engine and assembly of an aircraft engine and such a device

Abstract

Anti-free rotation device for aircraft engine and assembly of an aircraft engine and such a device One aspect of the invention relates to an anti-free rotation device (200) for an aircraft engine (100) comprising a fan (110) provided with a plurality of moving blades (115) mounted around a shaft (130), the anti-free rotation device comprising a weighted base (210) capable of being mounted between two consecutive blades (115a, 115b) of the fan of the engine. Another aspect of the invention relates to an assembly of an aircraft engine (100) and at least one anti-free rotation device (200) of the engine, in which the engine comprises a fan (110) upstream of a compressor assembly (120) and a turbine assembly (150) and the anti-free rotation device (200) is mounted between two consecutive blades (115a, 115b) of the fan of the engine to prevent any rotation of said fan. Figure to be published with the abstract: Figure 4

Description

Title of the invention: Anti-free rotation device for an aircraft engine and assembly of an aircraft engine and such a device TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an anti-free rotation device to be mounted in an aircraft engine fan to prevent any rotation of said engine under the effect of the wind. The invention also relates to an assembly formed by an aircraft engine and this anti-free rotation device.

[0002] The invention finds applications in the field of aeronautics and, in particular, in the field of maintenance and handling of aircraft engines when the aircraft are parked on the ground. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] A schematic example of an aircraft engine 100 is shown in [Fig.l]. This [Fig.l] shows a shaft 130 extending along a central axis AA and around which are mounted, in the upstream to downstream direction, a fan 110, a compressor assembly 120, a combustion chamber 140 and a turbine assembly 150. When the engine 100 is in operation, the air flow F, which enters the engine through the fan 110, is compressed by the compressor assembly 120, mixed and combusted with fuel in the combustion chamber 140, then expanded in the turbine assembly 150 before being discharged through the nozzle 160.

[0004] When an aircraft is on the ground, in the transport phase or in the parking phase, the aircraft engines, when stationary, are subject to climatic hazards. Each engine is, in particular, subject to the wind which tends to rush into the engine fan and to cause the moving parts of the engine, such as the fan blades of the low pressure (LP) compressor, to rotate freely, which causes the entire LP rotor line to rotate. This effect of the wind entering the engine fan and causing the blades to rotate freely is called "windmilling", in Anglo-Saxon terms.

[0005] An example of a fan 110, also called a Fan, of an aircraft engine is shown in [Fig. 2]. The fan 110 comprises a retention casing 112, or Fan casing, as well as a plurality of blades 115 fixed on the rotation shaft 130. When the wind rushes into the fan 110, the blades 115 of the fan are driven in a rotational movement, in the clockwise direction or in the counterclockwise direction as shown by the arrow R in [Fig. 2].

[0006] Under the effect of the wind, the rotation of the fan blades, integral with the LP rotor, causes, inside the engine, a free rotation of the moving parts of said engine such as the rotor blades. The free rotation of the rotor blades can cause premature wear and / or damage, by contact, of all the parts of the rotor line and the abradables of the stator opposite each other. Indeed, the rotation of the fan by the wind generates multiple transient phases and movements between parts with each rotation of the fan. As the rotations of the fan can easily reach the number of 60 per minute, the effects of the wind can have a real impact on the lifespan of the rotor parts and the abradables.

[0007] To protect the engines from these effects of the wind, it is possible to cover each engine, when the aircraft is on the ground, in order to prevent the wind from entering the engine fan. However, this technique of covering the engines is long and difficult to implement by an operator alone or without a lifting platform. In addition, due to the time required to install the cover, the latter cannot be installed between two flights of the aircraft.

[0008] In addition to the problem of premature wear of the rotor parts and stator abradables, the free rotation of the rotor under the effect of the wind can generate difficulties in inspecting the motor during its maintenance. Indeed, a maintenance operator can hardly carry out inspection operations, visual or by endoscopy, when the rotor is in free rotation; another operator must intervene to hold the fan and prevent it from rotating. However, since this holding of the fan is carried out with the operator's bare hands, the HSE (Health, Safety, Environment) professional risks are relatively high. Summary of the invention

[0009] To address the above-mentioned problems of premature wear of the rotor parts and stator abradables, the applicant proposes a free anti-rotation device to be mounted between two blades of the engine fan in order to prevent rotation of the fan, and therefore of the moving parts of the engine, under the effect of the wind.

[0010] In the remainder of the description, the terms "internal" and "external" define an element according to its radial position in the engine, an internal element being closer to the central axis AA of the engine than an external element. The terms "upstream" and "downstream" define an element according to its position relative to the circulation of air within the engine, the air circulating from the fan towards the nozzle.

[0011] According to a first aspect, the invention relates to an anti-free rotation device for an aircraft engine comprising a fan provided with a plurality of moving blades mounted around a shaft. It is characterized in that it comprises a weighted base capable of being mounted between two consecutive blades of the engine fan.

[0012] The free anti-rotation device allows the blower to be ballasted so that the blades of said blower are not rotated by the wind. Since the blades of the blower do not rotate under the effect of the wind, the air does not circulate inside the engine - or with insufficient force - and cannot freely rotate the moving parts of the engine such as the blades of the compressor assembly or the turbine assembly, which prevents premature wear of the moving parts of the engine and the parts in contact with these moving parts.

[0013] The free anti-rotation device constitutes a quick blocking tool for the fan, easily deployable between two flights.

[0014] In addition to the characteristics which have just been mentioned in the preceding paragraph, the free anti-rotation device according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations: • the base includes a complementary shape and dimensions of a spacing between the two consecutive blades of the fan. • the base comprises a first side and a second side, each covered with a flexible coating, shock and / or vibration absorber. • the flexible coating is made of elastomer. • the base has an oblique upstream face, equipped with a gripping system. • the gripping system has two separate handles.

[0015] A second aspect of the invention relates to an assembly of an aircraft engine and at least one device for preventing free rotation of the engine, the engine comprising a fan provided with a plurality of blades mounted around a shaft, upstream of a compressor assembly and a turbine assembly, characterized in that the device for preventing free rotation is as defined above and mounted between two consecutive blades of the engine fan to prevent any rotation of said fan.

[0016] This assembly has the advantage, when the aircraft is on the ground, in the parking position, that the engine is locked in rotation by the free anti-rotation device so that the moving parts of the engine are not driven in rotation under the effect of the wind. As explained above, the fact that the fan is weighted makes it possible to improve the service life of the moving parts of the engine as well as the fixed parts in contact with these moving parts. In addition, the fact that the fan is weighted makes it possible to easily block the rotation of the fan blades, which allows inspection operations, in particular endoscopy, in complete safety.

[0017] Advantageously, the anti-rotation device comprises an external surface in contact with a shell of the fan.

[0018] Advantageously, the assembly comprises a plurality of free anti-rotation devices, each mounted between two separate consecutive blades so as to distribute the ballast over the surface of the fan.

[0019] A third aspect of the invention relates to a method of maintaining an engine of an aircraft comprising a fan provided with a plurality of blades mounted around a shaft, upstream of a compressor assembly and a turbine assembly, said method comprising: • a step of positioning, between two consecutive blades of the engine fan, at least one free anti-rotation device as defined above, and • a step of repairing and / or checking the engine in which any free rotation of the blower is hindered by the anti-rotation device.

[0020] Advantageously, the control step of the maintenance method comprises an inspection, visual or by endoscopy, of the engine. BRIEF DESCRIPTION OF THE FIGURES

[0021] Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which:

[0022] [Fig.l], already described, represents a schematic view in longitudinal section of an example of an aircraft engine;

[0023] [Fig. 2], already described, represents a schematic perspective view of a aircraft engine fan exposed to wind;

[0024] [Fig. 3] schematically represents several perspective views of an example of free anti-rotation device according to the invention;

[0025] [Fig.4] represents a schematic perspective view of the anti-rotation device free of [Fig.3] mounted between two consecutive blades of an aircraft engine. DETAILED DESCRIPTION

[0026] An exemplary embodiment of a free anti-rotation device, configured to prevent rotation of an aircraft engine fan, is described in detail below, with reference to the accompanying drawings. This example illustrates the characteristics and advantages of the invention. It is however recalled that the invention is not limited to this example.

[0027] In the figures, identical elements are identified by identical references. For reasons of readability of the figures, the size scales between elements represented are not respected.

[0028] An example of a free anti-rotation device according to the invention is shown in [Fig. 3] and [Fig. 4]. The free anti-rotation device 200, more simply called an anti-rotation device, is designed to be installed in the fan 110 of the aircraft engine, between two consecutive blades 115a, 115b. It has a relatively high mass, called ballast, determined according to the engine, to stabilize the fan and prevent it from rotating under the effect of the wind, in particular a wind with a speed less than or equal to 15m / s. The shape of the anti-rotation device is adapted to match the spacing 116 between the two consecutive blades 115a, 115b of the blower 110 so that it is maintained between said blades in the presence of wind, without however generating too great a contact force on the blades themselves. Indeed, by having a shape complementary to the spacing between two blades 115, the anti-rotation device 200 has an optimal bearing surface against the fan while limiting the local mechanical forces against this same fan so as not to damage it and, in particular, not to damage its blades.

[0029] The anti-rotation device 200 comprises a weighted base 210, the shape of which at least partially matches the spacing 116 between two blades 115 of the fan. This base 210 forms a central body which can take various shapes provided that its width L corresponds substantially to the distance between two consecutive blades 115a, 115b and that its height H is less than the height of a blade 115, that is to say the distance between the shroud 112 of the fan and the rotation shaft 130 of the engine. The base 210 can, for example, have a cubic shape, a triangular prism shape, a right block shape or a polyhedron shape, whole or truncated, etc. In the examples of figures 3 and 4, the base 210 generally has the shape of a straight block truncated by an oblique plane.

[0030] In this example of figures 3 and 4, the base 210 comprises: • an external face 250 adapted to be in contact with the internal surface of the ferrule 112; the external face 250 may preferably be flat, the external face 250 is slightly curved in order to match the rounded shape of the internal surface of the ferrule 112; • a downstream face 270 extending substantially radially between the two consecutive blades 115a, 115b; this downstream face 270 extends substantially perpendicular to the external face 250; • two lateral faces 220, 230, called flanks, extending radially on either side of the external face 250 and the downstream face 270; each of the lateral faces 220, 230 extends partially along one of the blades 115a and 115b, substantially parallel to said blade 115a or 115b; • an upstream face 240, oblique, extending between the two lateral faces 220, 230 with an angle, relative to the external face 250, less than a right angle.

[0031] Whatever its overall shape, the base 210 is weighted so as to ensure its stability when it is mounted in the blower 110. In other words, the base 210 is made, partially or totally, from a dense and heavy material such as, for example, plastic materials of the polypropylene / polyethylene type or exotic woods of the teak type, or any other material having a density of around 1000 kg / m3. It can, for example, be formed by molding or cutting from one of these materials. It can, alternatively, comprise only a heavy base ensuring great stability for the base in its part closest to the shell 112.

[0032] When the base 210 is installed in the fan of the engine, the external face 250 of the base 210 extends substantially in the plane ZX of the XYZ reference frame shown in [Fig. 3], the downstream face 270 extends substantially in the plane XY and the flanks 220, 230 extend substantially in the plane YZ. The upstream face 240 extends obliquely between one end of the external face 250 and the top 280 of the base. In the embodiment of FIGS. 3 and 4, the upstream face 240 extends along a slope (i.e. it extends along an intermediate plane between the radial plane XY and the longitudinal plane XZ) so as to limit wind resistance. This slope is preferably regular between the upstream face 240 and the downstream face 270. Thus, the stability of the base 210 in the fan is obtained not only by its weight, but also by its low wind resistance.

[0033] The first flank 220 and the second flank 230 of the base 210 each have a shape adapted to match the shape of the adjacent blade 115. These flanks 220, 230 each have a non-planar surface, complementary to the surface of the adjacent blade 115. This complementary shape of the adjacent blade allows the base 210 to fit between the two consecutive blades 115a, 115b of the fan. In the example of FIGS. 3 and 4, the surface of each of the flanks 220, 230 comprises a radial projection designed to follow the profile of the adjacent blade. This projection preferably has a spherical or semi-spherical section in order to ensure linear contact facilitating the positioning of the anti-rotation device while limiting the contact zones.

[0034] In certain embodiments, the first and second flanks 220, 230 are each covered with a flexible, or supple, covering. This flexible covering forms, with the adjacent blade, an interface capable of absorbing the shocks and vibrations likely to be generated during the installation of the anti-rotation device 200 in the fan or by its removal or also by the wind rushing along said anti-rotation device. This flexible covering may be a layer of elastomer or any other flexible or elastic material, which absorbs vibrations and shocks.

[0035] The anti-rotation device 200 may comprise a gripping system 260 allowing an operator on the ground to easily install the anti-rotation device, after stopping the engine, and to easily remove it before starting the engine. This gripping system 260 may, for example, be positioned on the upstream face 240 of the base 210, this face being easily accessible to the operator at all times. In the example of FIGS. 3 and 4, the gripping system 260 comprises two handles 261, 262 positioned at a distance from each other, at the same radial height h. A single operator can thus take the anti-rotation device 200 with two hands to install it in the fan or remove it from the fan. The positioning of the handles is chosen so as to best balance the mass of the anti-rotation device to be moved, between the hands of the operator. In a variant, not shown in the figures, the two handles may be close to each other and / or at different radial heights.

[0036] The anti-rotation device as described above has the advantage of being easy to install and remove. It can therefore be installed as often as necessary, for example at each engine stop or at each engine inspection operation.

[0037] In some embodiments, the anti-rotation device 200 is made of a colored material or is painted at least partially in a colored color. In the example of Figures 3 and 4, the upstream face 240 is painted in a colored color, such as for example orange or red, so that the anti-rotation device is highly visible from the ground, during under-wing checks, in order to avoid forgetting it in the fan when the aircraft takes off.

[0038] The mass, or weight, of the anti-rotation device 200 can be defined according to the type of engine and / or for each wind configuration. In particular, several anti-rotation devices can be provided, for the same engine, with different masses in order to respond to the different wind configurations. Alternatively, it can be provided to install simultaneously, on the same fan, several anti-rotation devices, of lower mass, the number of devices installed depending on the wind configurations.

[0039] For example, for a continuous wind of 15m / s in the direction of the blower, the mass necessary to prevent the blower from rotating is estimated at 24kg. It may then be envisaged to install a single anti-rotation device of 24 kg or several anti-rotation devices whose total weight is equal to 24 kg. For example, two anti-rotation devices of 12 kg each may be installed between two separate pairs of fan blades or three anti-rotation devices of 8 kg each may be installed between three separate pairs of blades, the pairs of blades being able to be side by side or, on the contrary, at a distance from each other.The use of several anti-rotation devices, distributed over part of the circumference of the blower, not only improves the stability of the blower but also facilitates handling by the operator (due to the reduced mass of each anti-rotation device) and thus offers great flexibility of installation.

[0040] The anti-rotation device(s) 200 as described above may be mounted between two consecutive blades 115a, 115b of the engine fan as often as necessary. It may, for example, be mounted in anticipation of a maintenance operation, in order to allow a maintenance operator to control the engine in complete safety, i.e., being sure that the fan is not rotating. A maintenance operator can therefore control the engine, alone, without the assistance of a third party to prevent the fan from rotating. For this, the maintenance operator begins by positioning at least one anti-rotation device 200. A Once the anti-rotation device is in place between two consecutive blades, the operator can undertake engine checks, for example by visual inspection or endoscopy, as well as any necessary repairs.

[0041] Although described through a certain number of examples, variants and embodiments, the free anti-rotation device according to the invention includes various variants, modifications and improvements which will be obvious to those skilled in the art, it being understood that these variants, modifications and improvements are part of the scope of the invention.

Claims

Claims

1. Anti-free rotation device (200) for an aircraft engine (100) comprising a fan (110) provided with a plurality of moving blades (115) mounted around a shaft (130), characterized in that it comprises a weighted base (210), capable of being mounted between two consecutive blades (115a, 115b) of the engine fan, said base (210) comprising a shape and dimensions complementary to a spacing (116) between the two consecutive blades (115a, 115b) of the fan.

2. Device according to claim 1, characterized in that the base (210) comprises a first flank (220) and a second flank (230), each covered with a flexible coating, shock and / or vibration absorber.

3. Device according to claim 2, characterized in that the flexible coating is made of elastomer.

4. Device according to any one of claims 1 to 3, characterized in that the base (210) comprises an oblique upstream face (240), equipped with a gripping system (260).

5. Device according to claim 4, characterized in that the gripping system (260) comprises two separate handles (261, 262).

6. An assembly of an aircraft engine (100) and at least one anti-free rotation device (200) of the engine, the engine comprising a fan (110) provided with a plurality of blades (115) mounted around a shaft (130), upstream of a compressor assembly (120) and a turbine assembly (150), characterized in that the anti-free rotation device (200) is in accordance with any one of the preceding claims and mounted between two consecutive blades (115a, 115b) of the fan of the engine to prevent any rotation of said fan.

7. Assembly according to claim 6, characterized in that the anti-rotation device (200) comprises an external surface (250) in contact with a shroud (112) of the fan.

8. Assembly according to claim 6 or 7, characterized in that it comprises a plurality of free anti-rotation devices (200), each mounted between two separate consecutive blades (115a, 115b) so as to distribute the ballast over the circumference of the fan (110).

9. A method of maintaining an aircraft engine comprising a fan (110) provided with a plurality of blades (115) mounted around a shaft (130), upstream of a compressor assembly (120) and a turbine assembly (150), said method comprising: - a step of positioning, between two consecutive blades (115a, 115b) of the engine fan, at least one free anti-rotation device (200) according to any one of claims 1 to 5, and - a step of repairing and / or checking the engine in which any free rotation of the fan is hindered by the anti-rotation device.

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