Aircraft engine unit comprising an improved front engine attachment

An aircraft engine unit comprising an engine, a mast and an engine connection connecting the engine and the mast. The aircraft engine unit includes a front engine attachment of the engine connection which comprises at least one front rod connecting the primary structure of the mast and the core of the engine and which assures the take-up of vertical forces, and at least one connection connecting the primary structure of the mast and the fan casing of the engine and which assures the take-up of forces that are horizontal and perpendicular to the axis of rotation of the engine and/or a torque about the axis of rotation of the engine.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 15 58137 filed on Sep. 2, 2015, the entire disclosures of which are incorporated herein by way of reference.

BACKGROUND OF THE INVENTION

The present invention relates to an aircraft engine unit comprising an improved front engine attachment.

As illustrated inFIGS. 1 and 2, an aircraft10comprises a plurality of engine units12which are positioned below the wing14of the aircraft10in accordance with a configuration.

As illustrated inFIG. 2, an engine unit12comprises an engine15, a nacelle16positioned around the engine15and a mast18which assures the connection between the engine15and the rest of the aircraft10, in particular the wing14.

As illustrated inFIGS. 3A and 3B, the mast18comprises a rigid primary structure20which assures, amongst other things, the transmission of forces between the engine15and the rest of the aircraft10, and a secondary structure21which surrounds the primary structure20and which limits the drag of the mast.

The present invention is aimed more particularly at aircraft engines of the bypass turbojet type. As illustrated inFIGS. 3A and 3B, this type of engine15comprises a core22which, in particular, comprises a rotor that pivots relative to a stator about an axis of rotation24, and a fan casing26which has an approximately cylindrical shape and in which there is positioned a fan connected to the rotor of the core22of the engine.

Throughout the description, the terms front and rear refer to the direction of the flow of gases, the front corresponding to the intake of gases (air) into the engine and the rear corresponding to the exhaust of gases (combustion gases). In addition, an intermediate part of an element corresponds to a part disposed between a front part and a rear part. The terms top and bottom refer to the connections between the mast and the rest of the aircraft, the top corresponding to the connection between the mast and the wing of the aircraft and the bottom corresponding to the connection between the mast and the engine.

The core22extends from a front casing28comprising an air intake to a rear casing30comprising a combustion gas exhaust.

In accordance with one design, the primary structure20of the mast18is connected to the engine15by a connection which comprises a rear engine attachment32, a front engine attachment34, and a pair of thrust rods36which assure a take-up of the thrust forces.

In accordance with a first variant illustrated byFIG. 3Aand described in document FR-2.963.320, the rear engine attachment32connects an intermediate part38of the primary structure20of the mast18and the rear casing30of the core22of the engine15, the front engine attachment34connects the front end40of the primary structure20of the mast18and the front casing28of the core22of the engine15, and the thrust rods36connect the intermediate part38of the primary structure20and the front casing28of the core22of the engine. In accordance with a first disadvantage associated with this variant, the zone situated between the core22of the engine and the primary structure20is reduced and does not allow the integration of additional pieces of engine equipment, which are consequently positioned above the primary structure20of the mast. This arrangement leads to an increase in the volume of the secondary structure21and affects the drag of the aircraft.

In accordance with another disadvantage, this variant results in a relatively significant distance between the core22of the engine and the wing14.

In accordance with a second variant illustrated byFIG. 3B, the front engine attachment34connects the front end40of the primary structure20of the mast18and the fan casing26. This solution increases the zone situated between the core22of the engine and the primary structure20, which makes it possible to house additional pieces of engine equipment there. This variant also results in a reduction of the distance between the core22of the engine and the wing14. However, because the front end40of the primary structure20is positioned above the fan housing26, this second variant limits the diameter of the fan housing26. This diameter is tending to grow more and more due to the rise in the dilution ratio of new engines.

SUMMARY OF THE INVENTION

The present invention aims to overcome the disadvantages of the prior art.

To this end, the invention relates to an aircraft engine unit comprising an engine, a mast and a nacelle in which there is positioned the engine, the engine comprising:a core which comprises a stator and a rotor, the rotor pivoting about an axis of rotation relative to the stator,a fan connected to the rotor and positioned in a fan housing,

the mast comprising a primary structure connected to the engine by an engine connection which comprises:a rear engine attachment which connects an intermediate part of the primary structure and the core of the engine,a front engine attachment which connects a front end of the primary structure and the engine, andat least two thrust rods.

In accordance with the invention, the aircraft engine unit is characterized in that the front engine attachment comprises at least one connection which connects the primary structure of the mast and the fan casing of the engine, and at least one front rod which connects the primary structure of the mast and the core of the engine, and in that each front rod is connected at a first end to a front end of the primary structure of the mast by a connection pivoting about a horizontal axis perpendicular to the axis of rotation of the engine and is connected at a second end to the core of the engine by a connection pivoting about a horizontal axis perpendicular to the axis of rotation of the engine.

In accordance with a first advantage, this configuration makes it possible to be able to house at least one additional piece of equipment in a zone situated between the core of the engine and the primary structure of the mast.

In accordance with another advantage, because the front end is offset vertically relative to the rear engine attachment, the distance separating the core of the engine and the wing is reduced.

In accordance with another advantage, the diameter of the fan housing determining the dilution ratio of the engine is not limited by the distance separating the front end of the primary structure of the mast and the ground.

In accordance with another advantage, the forces associated with the weight of the engine are taken up by the front rod at the core of the engine, which tends to reduce the stresses on the fan casing.

The front rod is preferably connected to a part of the stator, and the orientation of the front rod is convergent with the axis of rotation in a plane perpendicular to the axis of rotation, the plane containing a front bearing assuring the guidance in rotation of the rotor relative to the stator and positioned further to the front of the engine.

In accordance with a further feature, the connection which connects the primary structure of the mast and the fan casing comprises at least one pair of connection elements disposed in a plane perpendicular to the axis of rotation, each connection element of the pair being symmetrical to the other connection element with respect to the primary structure, each connection element being connected on the one hand to the primary structure and on the other hand to the fan casing or to at least one element of the nacelle rotationally fixed about the axis of rotation relative to the fan casing.

In accordance with a first variant, the connection comprises two lateral rods, each of which comprises a first end connected to the primary structure by a connection pivoting about an axis parallel to the axis of rotation and a second end connected to the fan casing by a connection pivoting about an axis parallel to the axis of rotation.

In accordance with a second variant, the connection comprises at least one first connection element connecting a first cowling of the nacelle to the primary structure of the mast and at least one second element connecting a second cowling of the nacelle to the primary structure of the mast, the first and second cowlings being rotationally fixed about the axis of rotation relative to the fan casing.

In accordance with a first embodiment, the first and second connection elements are present in the form of at least one bracket disposed in a plane perpendicular to the axis of rotation, comprising a central part fixed to the primary structure of the mast and extending on either side of the primary structure, symmetrically, the bracket comprising ends connected to the first and second cowlings of the nacelle.

In accordance with a second embodiment, the first and second connection elements are lateral rods disposed on either side of the primary structure, each lateral rod comprising a first end connected by means of a joint to the primary structure and a second end connected to one of the cowlings. Each joint is preferably a pivot connection with a vertical pivot axis.

The invention also relates to an aircraft comprising at least one engine unit according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

InFIGS. 4, 8 and 9, reference sign50denotes an engine unit of an aircraft, which engine unit comprises an engine52, a mast54and a nacelle56(only visible in part inFIGS. 8 and 9).

In accordance with one embodiment, the engine52is a bypass turbojet. It comprises:

a core58which comprises a rotor60pivoting about an axis of rotation62relative to a stator64which comprises a front casing66with an air inlet and a rear casing68with a combustion gas exhaust,

a fan connected to the rotor60and positioned in a fan casing70connected to the front casing66by radial arms.

The front casing66, rear casing68and fan casing70are approximately concentric with the axis of rotation62. In addition, the engine52comprises bearings assuring the guidance in rotation of the rotor60relative to the stator64. One of the bearings is positioned further to the front of the engine52, inside the front casing66, and is referred to as the front bearing72.

For the following description, an axis X coincides with the axis of rotation62of the engine52, an axis Y is perpendicular to the axis X and horizontal, and an axis Z is perpendicular to the axis X and vertical. A vertical longitudinal plane contains the axis X and the axis Z, a horizontal longitudinal plane contains the axis X and the axis Y, and a transverse plane is a plane perpendicular to the axis X.

In accordance with a configuration illustrated byFIG. 4, the mast54makes it possible to connect the engine unit50to a wing74, the engine unit50being positioned below the wing74.

The mast54comprises a primary structure76positioned in a fairing (not shown) which confers aerodynamic properties to the mast54. In accordance with one embodiment, the primary structure76is a box-like structure comprising an upper stringer78, a lower stringer80, side panels84and stiffeners86.

The primary structure76is connected by a wing connection94to the wing74and is connected by an engine connection to the engine52.

In accordance with one configuration, the engine connection comprises a rear engine attachment88which connects an intermediate part90of the primary structure76and the core58of the engine52, more particularly the rear casing68. The engine connection also comprises a front engine attachment92which connects a front end102of the primary structure76and the engine52. Lastly, the engine connection also comprises at least two thrust rods96disposed symmetrically with respect to the vertical longitudinal plane and which connect the intermediate part90of the primary structure76and the core58of the engine52, more particularly the front casing66.

In accordance with one embodiment, the primary structure76of the mast has an approximately triangular section in a vertical longitudinal plane, a substantially horizontal first side of said section forming the upper stringer78, the lower stringer80forming a second side of the triangle positioned to the front, a rear stringer98(visible inFIG. 4) connecting the upper stringer78and lower stringer80. The lower stringer80and the rear stringer98are connected at a bottom edge100offset downwardly relative to the upper stringer78.

The upper stringer78and the lower stringer80are joined or are separated by a short distance at the front end102.

In accordance with one embodiment, in a view from above the side edges of the upper stringer78and lower stringer80are convergent toward the front, such that the front end102forms a point oriented toward the front.

The front engine attachment92is positioned at the front end102of the primary structure76of the mast54, and the rear engine attachment88is positioned at the lower stringer80in the proximity of the bottom edge100.

In accordance with one feature of the invention, the front engine attachment92comprises at least one front rod104which connects the primary structure76of the mast54and the core58of the engine52, and at least one connection106which connects the primary structure76of the mast54and the fan casing70.

In accordance with this configuration, the front end102of the primary structure76of the mast54is spaced from the core58of the engine52, which makes it possible to house at least one additional piece of equipment108in a zone situated between the core58of the engine and the primary structure76. Thus, this configuration tends to reduce the volume enclosed by the fairing of the mast54and therefore tends to limit the impact on the aerodynamic properties of the engine unit50.

In accordance with another advantage, because the front end102is offset vertically relative to the rear engine attachment88, the distance separating the core58of the engine52and the wing74is reduced.

In accordance with another advantage, the front end102of the primary structure76of the mast54is offset toward the rear relative to the fan casing70and is no longer positioned above said fan casing70. Consequently, the diameter of the fan casing70determining the dilution ratio of the engine52is no longer limited by the distance separating the front end102of the primary structure76of the mast54and the ground S.

In accordance with another advantage, the forces along the axis Z are taken up by the front rod104at the core58of the engine52, which tends to reduce the stresses on the fan casing70. In accordance with one embodiment, the front engine attachment92comprises a sole front rod104connected to the front end102of the primary structure76of the mast54and disposed in the vertical longitudinal plane. With the presence of a plurality of front rods104, these are disposed symmetrically with respect to the vertical longitudinal plane.

Each front rod104is preferably connected at each of its ends either to the primary structure76or to the engine52by a joint allowing at least 1° of freedom in the direction of the axis Y. The front rod104thus assures the take-up of forces in the direction of the axis Z.

Each end of each front rod104advantageously pivots relative to an axis of rotation110,110′ parallel to the axis Y.

In accordance with an embodiment visible inFIGS. 6 and 7, the front end102of the primary structure76of the mast54comprises a clevis112with two tabs disposed on either side of the front rod104, and a first end of the front rod104comprises a bore through which the axis of rotation110passes supported by the clevis112.

In accordance with another embodiment visible inFIG. 10, the front end102comprises a connection plate114disposed in the vertical longitudinal plane. The connection plate114comprises a bore through which an axis of rotation110passes which is supported by a clevis116connected to the front bore104.

In accordance with an embodiment visible inFIGS. 10 and 11, a clevis118connected to the core58of the engine52comprises two tabs which support an axis of rotation110′, a second end of the front rod104comprising a bore through which the axis of rotation110′ passes.

The front rod104is preferably connected to part of the stator64such that the orientation of the front rod104is convergent with the axis X in a transverse plane containing the front bearing72. Thus, the flexion between the rotor60and the stator64is reduced.

In accordance with a first variant visible inFIGS. 5 to 7, the connection106of the front engine attachment92directly connects the primary structure76and the fan casing70.

The connection106preferably comprises two lateral rods120,120′ disposed in a transverse plane, on either side of the primary structure76.

Each lateral rod120,120′ is connected at a first end to the front end102of the primary structure76of the mast54and at a second end to the fan casing70. Each end of each lateral rod120,120′ is connected either to the front end102or to the fan casing70by a joint.

In accordance with one embodiment, the front end102of the primary structure76of the mast54comprises a plate122with ears124on either side, each of which is connected to a lateral rod120,120′ via an axis of rotation126parallel to the axis X. In accordance with this embodiment, each lateral rod120,120′ can pivot about the axis of rotation126in a transverse plane. The plate122preferably comprises the clevis112connected to the front rod104.

Each lateral rod120,120′ comprises, at each end, bores128,128′ oriented in accordance with the axis X, one bore128accommodating the axis of rotation126connected to the primary structure76and one bore128′ accommodating an axis of rotation130connected to the fan casing70.

In accordance with a second variant visible inFIGS. 8 to 11, the connection106of the front engine attachment indirectly connects the primary structure76and the fan casing70.

The nacelle56is on the one hand connected to the mast54, more particularly to the primary structure76of the mast54, and on the other hand is rotationally fixed about the axis X relative to the fan casing70.

In accordance with one embodiment, the nacelle56comprises two cowlings132and132′ approximately symmetrical with respect to the vertical longitudinal plane. Each cowling132,132′ has a semi-cylindrical shape and comprises a first edge136,136′ connected by a connection134,134′ to the mast54, and a second edge opposite the first edge136,136′.

In accordance with one embodiment, the connection between each cowling132and132′ and the mast54is a pivot connection, each cowling132,132′ being movable relative to the mast54about a pivot axis138,138′ between an open position, in which the second edges of the cowlings132,132′ are spaced apart, and a closed position, in which the second edges are joined, a locking/unlocking system ensuring that the cowlings132,132′ are held in the closed position. In this closed position, the cowlings132,132′ are rotationally fixed about the axis X relative to the fan casing70.

The connection134,134′ preferably comprises, for each cowling132,132′, at least one connection element140,140′ disposed in a transverse plane, connected on the one hand to the primary structure76of the mast54and on the other hand to the cowling132,132′.

The connection elements140connecting the first cowling132to the primary structure76of the mast54are advantageously aligned with the connection elements140′ of the second cowling132′ in order to limit the occurrence of moments in the primary structure76.

In accordance with a first configuration, the connection elements140,140′ are fixed relative to the primary structure76. In accordance with one embodiment, the connection elements140,140′ are present in the form of at least one bracket142disposed in a transverse plane, of which the central part is fixed to the upper stringer78of the primary structure76and which extends on either side of the primary structure76, symmetrically, the bracket142comprising a bore144,144′ at each end, a first bore144assuring the guidance of the pivot axis138of the first cowling132, and the second bore144′ assuring the guidance of the pivot axis138′ of the second cowling132′.

In accordance with a second configuration, the connection elements140,140′ are hinged relative to the primary structure76of the mast54. In accordance with one embodiment, the connection elements140,140′ are lateral rods146,146′ disposed on either side of the primary structure76, each lateral rod146,146′ comprising a first end connected, thanks to a joint148, to a plate150fixed on the upper stringer78of the primary structure76and a second end which comprises a bore152,152′ assuring the guidance of one of the pivot axes138,138′ of the cowlings132,132′.

Depending on the situation, the joint148is a pivot connection with a pivot axis oriented along the axis Z as illustrated inFIGS. 9 and 10or with a pivot axis oriented along the axis X.

In accordance with the second variant, the connection elements140,140′ are symmetrical with respect to the vertical longitudinal plane. As illustrated inFIGS. 9 and 10, some connection elements140,140′ can be fixed and others hinged relative to the primary structure76of the mast54.

Regardless of the variant, the connection106of the front engine attachment which directly or indirectly connects the primary structure76and the fan casing70comprises at least one pair of connection elements disposed in a transverse plane, symmetrically with respect to the primary structure76, each connection element being connected on the one hand to the primary structure76and on the other hand to the fan casing70or to at least one nacelle element rotationally fixed about the axis X with respect to the fan casing70. Thus, these connection elements120,140,140′ assure the take-up of forces along the axis Y and/or a torque along the axis X. The connection of the connection elements to the fan casing makes it possible to space these apart from the axis of rotation62of the engine52and to increase their ability to take up the forces along the axis Y and/or a torque along the axis X.

In accordance with the invention, forces oriented vertically along the axis Z are taken up by the front rod(s)104and not by the connection106, and forces along the axis Y and/or a torque along the axis X are taken up by the connection106and not by the front rod(s)104. Separating the take-up of forces or torques between the engine and the mast makes it possible to optimize the configuration of the front rod(s)104, which are designed to take up forces along the axis Z, and the configuration of the connection106, which is designed to take up forces along the axis Y and/or a torque along the axis X.