FR3136257A1 - Anti-free rotation device for an aircraft engine and assembly of an aircraft engine and such a device - Google Patents

Abstract

Anti-free rotation device for an 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. aircraft (100) comprising a fan (110) provided with a plurality of movable blades (115) mounted around a shaft (130), the free anti-rotation device comprising a weighted base (210) capable of being mounted between two consecutive blades (115a, 115b) of the engine fan. 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) in 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 engine fan to prevent any rotation of said blower. Figure to be published with the abstract: Figure 4

Description

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

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 of an aircraft engine and this anti-free rotation device.

The invention finds applications in the field of aeronautics and, in particular, in the field of maintenance and handling of aircraft engines when aircraft are parked on the ground.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

A schematic example of an aircraft engine 100 is shown on the . This shows a shaft 130 extending along a central axis AA and around which are mounted, in the upstream to downstream direction, a blower 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 blower 110, is compressed by the compressor assembly 120, mixed and burned with fuel in the combustion chamber 140, then expanded in the turbine assembly 150 before being evacuated through the nozzle 160.

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

An example of a fan 110, also called Fan, of an aircraft engine is shown on the . 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, clockwise or counterclockwise as represented by the arrow R on the .

Under the effect of the wind, the rotation of the fan blades, integral with the LP rotor, generates, 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, to all the parts of the rotor line and the abradables of the stator opposite. In fact, the rotation of the fan by the wind generates multiple transient phases and movements between parts with each rotation of the fan. Since the fan rotations can easily reach 60 per minute, the effects of wind can have a real impact on the lifespan of rotor parts and abradables.

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 rushing into the engine fan. However, this engine covering technique 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 tarpaulin, it cannot be installed between two aircraft flights.

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

To respond to the problems mentioned above of premature wear of 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 moving parts of the engine, under the effect of the wind.

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 in relation to the air circulation within the engine, the air circulating from the fan towards the nozzle.

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 by the fact that it includes a weighted base capable of being mounted between two consecutive blades of the engine fan.

The free anti-rotation device makes it possible to ballast the fan so that the blades of said fan are not rotated by the wind. As the fan blades do not rotate under the effect of the wind, the air does not circulate inside the engine – or with insufficient force – and cannot cause the moving parts of the engine such as the blades to rotate freely. of the compressor assembly or the turbine assembly, which avoids premature wear of the moving parts of the engine and the parts in contact with these moving parts.

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

• l’embase comprend une forme et des dimensions complémentaires d’un espacement entre les deux aubes consécutives de la soufflante.
• l’embase comprend un premier flanc et un second flanc, recouverts chacun d’un revêtement flexible, absorbeur de chocs et/ou vibrations.
• le revêtement flexible est en élastomère.
• l’embase comporte une face amont oblique, équipée d’un système de préhension.
• le système de préhension comporte deux poignées distinctes.

In addition to the characteristics which have just been mentioned in the previous 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 in all technically possible combinations:

• the base comprises a shape and dimensions complementary to 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, absorbing shocks and/or vibrations.
• the flexible covering is made of elastomer.
• the base has an oblique upstream face, equipped with a gripping system.
• the gripping system has two separate handles.

A second aspect of the invention relates to an assembly of an aircraft engine and at least one anti-free rotation device 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 free anti-rotation device is as defined above and mounted between two consecutive blades of the engine fan to prevent any rotation of said fan

This assembly has the advantage, when the aircraft is on the ground, in the parking position, that the engine is blocked in rotation by the free anti-rotation device so that the moving parts of the engine are not rotated under the effect of the wind. As explained above, the fact that the blower is ballasted improves the lifespan 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 ballasted makes it easy to block the rotation of the fan blades, which allows inspection operations, particularly endoscopy, in complete safety.

Advantageously, the anti-rotation device comprises an external surface in contact with a shroud of the fan.

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

• une étape de positionnement, entre deux aubes consécutives de la soufflante du moteur, d’au moins un dispositif d’anti-rotation libre tel que défini ci-dessus, et
• une étape de réparation et/ou de contrôle du moteur dont toute rotation libre de la soufflante est entravée par le dispositif d’anti-rotation.

A third aspect of the invention relates to a method of maintaining an aircraft engine 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 motor in which any free rotation of the fan is hindered by the anti-rotation device.

Advantageously, the control step of the maintenance process includes an inspection, visual or by endoscopy, of the engine.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages and characteristics of the invention will appear on reading the description which follows, illustrated by the figures in which:

There , already described, represents a schematic view in longitudinal section of an example of an aircraft engine;

There , already described, represents a schematic perspective view of an aircraft engine fan subjected to the wind;

There schematically represents several perspective views of an example of a free anti-rotation device according to the invention;

There represents a schematic perspective view of the free anti-rotation device of the mounted between two consecutive blades of an aircraft engine.

DETAILED DESCRIPTION

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

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.

An example of a free anti-rotation device according to the invention is shown on the and the . The free anti-rotation device 200, more simply called 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 fan 110 so that it is maintained between said blades in the presence of wind, without however generating a force of rotation. too much contact on the blades themselves. Indeed, by having a shape complementary to the spacing between two blades 115, the anti-rotation device 200 presents an optimal bearing surface against the fan while limiting the local mechanical forces against this same fan so as not to not damage it and, in particular, not damage its blades.

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 varied shapes as long as its width L corresponds substantially to the distance between two consecutive blades 115a, 115b and its height H is less than the height of a blade 115, i.e. that is to say the distance between the shroud 112 of the fan and the rotation shaft 130 of the motor. The base 210 can, for example, have a cubic shape, a triangular prism shape, a straight block or 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.

• une face externe 250 adaptée pour être en contact avec la surface interne de la virole 112 ; la face externe 250 peut être plane de préférence, la face externe 250 est légèrement cintrée afin d’épouser la forme arrondie de la surface interne de la virole 112 ;
• une face aval 270 s’étendant sensiblement radialement entre les deux aubes consécutives 115a, 115b ; cette face aval 270 s’étend de façon sensiblement perpendiculaire à la face externe 250 ;
• deux faces latérales 220, 230, appelées flancs, s’étendant radialement de part et d’autre de la face externe 250 et de la face aval 270 ; chacune des faces latérales 220, 230 s’étend partiellement le long d’une des aubes 115a et 115b, de façon sensiblement parallèle à ladite aube 115a ou 115b ;
• une face amont 240, oblique, s’étendant entre les deux faces latérales 220, 230 avec un angle, par rapport à la face externe 250, inférieur à un angle droit.

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 can 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 sides, extending radially on either side of the external face 250 and the downstream face 270; each of the side 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.

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, in a dense material and weighing as , for example, plastic materials such as polypropylene/polyethylene or exotic woods such as teak, or any other material with a density of around 1000 kg/m³ . It can for example be formed by molding or cutting in one of these materials. It can, alternatively, include only a heavy base ensuring great stability to the base in its part closest to the ferrule 112.

When the base 210 is installed in the engine fan, the external face 250 of the base 210 extends substantially in the plane ZX of the mark XYZ represented in , the downstream face 270 extends substantially in the XY plane and the flanks 220, 230 extend substantially in the YZ plane. 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 Figures 3 and 4, the upstream face 240 extends along a slope (that is to say 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.

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

In certain embodiments, the first and second sides 220, 230 are each covered with a flexible, or soft, coating. This flexible covering forms, with the adjacent blade, an interface capable of absorbing 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 can be a layer of elastomer or any other flexible or elastic material, absorbing vibrations and shocks.

The anti-rotation device 200 may include 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 can, for example, be positioned on the upstream face 240 of the base 210, this face being easy to access for the operator at any time. In the example of Figures 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 both hands to install it in the blower or remove it from the blower. 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 can be close to each other and/or at different radial heights.

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 each time the engine is stopped or each engine inspection operation.

In certain 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 orange or red, so that the anti-rotation device is clearly visible from the ground, when under-wing checks, in order to avoid forgetting the fan when departing the aircraft.

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 different wind configurations. Alternatively, it can be planned to install several anti-rotation devices of lower mass simultaneously, on the same fan, the number of devices installed depending on the wind configurations.

For example, for a continuous wind of 15m/s in the direction of the fan, the mass necessary to prevent the fan from rotating is estimated at 24kg. It can then be considered 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 can be installed between two separate pairs of fan blades or three anti-rotation devices of 8 kg each can be installed between three separate pairs of blades, the pairs of blades can 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, makes it possible not only to improve the stability of the blower but also to facilitate handling by the operator (due to a mass by lightweight anti-rotation device) and, thus, offer great installation flexibility.

The anti-rotation device(s) 200 as described above can be mounted between two consecutive blades 115a, 115b of the engine fan as often as necessary. It can, for example, be mounted in anticipation of a maintenance operation, in order to allow a maintenance operator to check the engine in complete safety, that is to say while being sure that the fan is not rotating. A maintenance operator can therefore control the motor alone, without the assistance of a third person to prevent the fan from rotating. To do this, the maintenance operator begins by positioning at least one anti-rotation device 200. Once the anti-rotation device is in place between two consecutive blades, the operator can carry out checks of the engine, for example by visual inspection or by endoscopy, as well as necessary repairs.

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

Claims (10)

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. Device according to claim 1, characterized in that the base (210) comprises a shape and dimensions complementary to a spacing (116) between the two consecutive blades (115a, 115b) of the fan. Device according to claim 1 or 2, characterized in that the base (210) comprises a first side (220) and a second side (230), each covered with a flexible coating, absorbing shocks and/or vibrations. Device according to claim 3, characterized in that the flexible coating is made of elastomer. Device according to any one of claims 1 to 4, characterized in that the base (210) has an oblique upstream face (240), equipped with a gripping system (260). Device according to claim 5, characterized in that the gripping system (260) comprises two distinct handles (261, 262). 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 free anti-rotation device (200) conforms to any one of the preceding claims and mounted between two consecutive blades (115a, 115b) of the engine fan to prevent any rotation of said fan. Assembly according to claim 7, characterized in that the anti-rotation device (200) comprises an external surface (250) in contact with a shroud (112) of the fan. Assembly according to claim 7 or 8, characterized in that it comprises a plurality of free anti-rotation devices (200), each mounted between two distinct consecutive blades (115a, 115b) so as to distribute the ballast over the circumference of the blower (110). 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 6, and
• a step of repairing and/or checking the motor in which any free rotation of the fan is hindered by the anti-rotation device.