Aircraft engine mount structure comprising two thrust links with transverse fitting

A mounting structure for an aircraft engine including a rigid structure and a mechanism to mount the engine on the rigid structure. The mounting mechanism includes a thrust load device including two side thrust links each including an aft end mounted on an evener bar of the device, via a mechanical connection. Each connection is formed by a lug provided on the evener bar and passing through an orifice made in the aft end, the lug being arranged so as to extend substantially laterally relative to the mounting structure.

TECHNICAL AREA

The present invention generally relates to an aircraft engine mount intended to be positioned between an aircraft wing and its related engine, and to an engine assembly comprising said mount.

The invention can be used on any type of aircraft equipped with turbo-jet engines or turboprop engines.

This type of mount called “EMS” for Engine Mounting Structure, can be used indifferently to mount an engine below the aircraft wing, to mount this engine above this same wing, or to position this engine on an aft portion of the aircraft fuselage.

STATE OF THE PRIOR ART

Said mounting structure is designed to form a connecting interface between a gas turbine engine and an aircraft wing. It permits the loads generated by its associated gas turbine engine to be transmitted to the frame of this aircraft, and also provides a pathway for fuel lines, electrical, hydraulic and air systems between the engine and the aircraft.

To ensure the transmission of loads, the mounting structure comprises a rigid structure called a primary structure often of “box” type, i.e. formed by the assembly of upper and lower spars and side panels joined together via transverse ribs.

In addition, the device is provided with mounting means placed between the gas turbine engine and the rigid structure, these means globally comprising two engine attachments, and a thrust device to transmit the thrust loads generated by the gas turbine engine.

In the prior art, this thrust transfer device comprises two side links for example, joined firstly to the case of the gas turbine engine and secondly to an evener bar itself being pivot mounted on the rigid structure of the mounting structure.

Similarly, the mounting structure also comprises another series of attachments forming a mounting system positioned between the rigid structure and the aircraft wing, this system usually consisting of two or three attachments.

Finally, the pylon is provided with a secondary structure ensuring segregation and supporting of aircraft systems whilst carrying aerodynamic cowling.

As mentioned above, the solutions proposed in the prior art provide that the thrust load transfer device integrates two side links each having an aft end pivoted on the side end of the evener bar associated therewith, by means of a hinge pin passing through the thrust link and the evener bar.

Generally, this hinge pin extends substantially vertically and parallel to the pin on which the evener bar is hinged on the connecting bracket secured to the rigid structure of the mounting structure, so as to allow good balancing of this evener bar.

If the thrust load device is assembled between the engine and the rigid structure, it is no longer possible to disconnect/reconnect the thrust links on the evener bar, such operations nonetheless being desired, for example for later dismounting of the engine. It is therefore necessary to carry out disconnection/reconnection of the entire evener bar carrying the thrust links by dismounting/mounting the hinge pin of this evener bar on the rigid structure.

However, this manner of proceeding requires the positioning of large-size tooling in an area that is little accessible and much congested. The lower end of the evener bar hinge pin, intended to cooperate with the tooling, effectively lies very close to the gas turbine engine casing which it faces.

Hence the setting up and handling of this tooling generate high risks of deteriorating the engine assembly, and at all events are synonymous with operating difficulties that are penalizing in terms of assembly time. By way of indication, these disadvantages are particularly encountered when the tooling is placed in position between the casing of the gas turbine engine and the underside of the evener bar pivot mounted about the above-mentioned hinge pin.

SUMMARY OF THE INVENTION

The purpose of the invention is therefore to propose a mounting structure and an engine assembly comprising said device with which to overcome the above-described disadvantages related to prior art embodiments.

For this purpose, the subject-matter of the invention is a mounting structure for aircraft engine comprising a rigid structure and means to mount the engine on the rigid structure, the mounting means comprising a thrust load device to transmit loads generated by the engine, this thrust load device comprising two side thrust links each having an aft end mounted on the evener bar of the device, via a mechanical connection. According to the invention, each mechanical connection is achieved by means of a lug provided on the evener bar and passing through an orifice made in the aft end of the associated thrust link, this lug being arranged so as to extend substantially cross-wise relative to the mounting structure.

Therefore, with this configuration particular to the invention, in which each lug extends substantially in transverse direction to the device or slightly at an angle thereto, it becomes easily possible to disconnect/reconnect the aft end of each of the side thrust links e.g. for an engine dismounting/remounting operation. On this account, it is advantageously no longer necessary to dismount/remount the evener bar assembly when carrying out this type of operation.

The setting up and handling of the tooling required to mount/dismount each of the side thrust links generate practically no risk of deteriorating the engine assembly, insofar as the free end of each lug is oriented towards an area of this engine assembly that is little congested. In this respect, it is specified that as a consequence the tooling required is advantageously less voluminous than required in the prior art to ensure dismounting/remounting of the evener bar assembly carrying the aft ends of the side thrust links.

Additionally, the easy mounting provided by said arrangement allows savings in terms of assembly time, this also being optimized by the fact that the aft ends of the side thrust links can henceforth be easily interlocked into their associated lug by a mere substantially lateral movement of these links initially connected to the engine via their forward end.

Preferably, provision is made so that each lug extends along an axis lying in a solid angle in the form of a cone of revolution whose central axis corresponds to a transverse direction of the mounting structure, and having a value equal to or less than 2π·(1−cos(15°)) sr, this characteristic illustrating the notion of substantially transversal extension of the above-mentioned lugs. The value indicated above translates a solid angle in the form of a cone of revolution whose generatrix is distanced away from the central axis by an angle of 15°.

Again to illustrate this notion, provision is preferably made so that, from an overhead view, each lug therefore extends along an axis forming an angle having a value equal to or less than 15° with a transverse direction of the mounting structure and/or so that from a front view each lug extends along an axis having an angle equal to or less than 15° with this transverse direction.

Preferably, for each mechanical connection, the orifice made in the aft end of the thrust link is equipped with a ball joint through which the lug on the evener bar is passed.

Preferably, the evener bar is pivoted about a hinge pin which also passes through a bracket for connection to the rigid structure, the thrust load device also comprising an abutment bracket in the shape of a horse-shoe whose central part is crossed by the hinge pin and which is intended to be fixedly joined to the rigid structure, the horse-shoe shaped abutment bracket having an abutment surface located aftwardly relative to the evener bar so that it is able to stop rotation of this evener bar about its hinge pin in both directions.

Preferably, the engine mount means also comprise a forward engine attachment and an aft engine attachment fixed to the rigid structure, the forward engine attachment being designed to transmit loads exerted along a transverse direction of the device and along the vertical direction of the device, and the aft engine attachment being designed to transmit loads exerted along the transverse and vertical directions of the device and to ensure transmission of the moment exerted along a longitudinal direction of this device.

As is usually the case, the two side thrust links are preferably arranged either side of a vertical, longitudinal median plane of the mounting structure.

A further subject-matter of the invention is an engine assembly comprising an engine such as a gas turbine engine and a mounting structure for this engine, the mounting structure being such as the one just described.

Finally, the invention also relates to an aircraft comprising at least one engine assembly such as indicated above, assembled onto a wing or an aft fuselage part of this aircraft.

Other advantages and characteristics of the invention will become apparent from the detailed, non-limiting, description given below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference toFIG. 1, an aircraft engine assembly1can be seen, intended to be secured below a wing2of this aircraft which is solely illustrated as a dashed outline for reasons of clarity, this assembly1comprising a mounting structure4according to one preferred embodiment of the present invention, an engine6e.g. a turbo-jet engine being mounted below this device4.

Globally, the mounting structure4comprises a rigid structure8carrying means to mount the engine6, these mounting means having a plurality of engine attachments10,12, and a thrust load device14to transmit the thrust loads generated by the engine6.

By way of indication, it is noted that the assembly1is intended to be surrounded by a nacelle (not shown) and the mounting structure4comprises another series of attachments16for the mounting of this assembly1below the wing2of the aircraft.

In the remainder of the following description, X designates the longitudinal direction of the device4which is comparable to the longitudinal direction of the gas turbine engine6and of device14, this direction X being parallel to a longitudinal axis5of the turbo-jet engine6. Y is used to designate the transverse-oriented direction relative to the device4and is comparable to the transverse direction of the turbo-jet engine6and of device14, and Z designates the vertical direction or height, these three directions, X, Y and Z lying orthogonal to each other.

Also the terms “forward” and “aft” are to be considered relative to the direction of travel of the aircraft subsequent to the thrust exerted by the turbo-jet engine6, this direction being schematically represented by arrow7.

FIG. 1illustrates the two engine attachments10,12, the series of attachments16, the thrust load device14and the rigid structure8of the mounting structure4. The other constituent elements of this device4that are not shown, such as the secondary structure ensuring segregation and supporting of the systems whilst carrying the aerodynamic cowling, are conventional elements identical or similar to those found in the prior art and known to those skilled in the art. They are therefore not described in detail.

Also, it is indicated that the turbo-jet engine6is equipped forwardly with a large-size fan case18delimiting an annular fan duct20, and aftwardly comprises a central casing22of smaller size, enclosing the core of this turbo-jet engine. The casings18and20are evidently secured to one another.

As can be seenFIG. 1, the engine attachments10,12of the device4are designed to be two in number and are respectively called the forward engine attachment and the aft engine attachment.

In this preferred embodiment of the present invention, the rigid structure8is in the form of a box extending from aft to forward substantially along direction X.

The box is then in the form of a pylon of similar design to that usually seen for mounting pylons of turbo-jet engines, particularly in that it is formed of the assembly of an upper spar15, a lower spar17and two side spars/panels19(only one being visible since this is a side view), these parts15,17,19being connected together via transverse ribs21each globally assuming the form of a rectangle. Therefore the ribs21extend along planes YZ, the spars15,17roughly extend along planes XY, and the side panels19along planes XZ.

The mounting means in this preferred embodiment firstly comprise the forward engine attachment10positioned between a forward end of the of the rigid structure8, also called a pyramid, and an upper portion of the fan case18. Nevertheless, it would also be possible to provide for the forward engine attachment10to be fixed to a connecting case between the central casing and the fan case as is known to those skilled in the art. The forward engine attachment10, of conventional design and known to persons skilled in the art, is attached to a first point P1of the rigid structure8, this structure also being called a primary structure.

Also, the aft engine attachment12, also of conventional design known to those skilled in the art, is positioned between the rigid structure8and the central casing22, and is attached to a second point P2of the rigid structure8positioned aftward relative to point P1.

In this preferred embodiment, the thrust load device14is attached to a third point P3of the rigid structure8, point P3being located between points P1and P2.

Globally the thrust load device14has two side thrust links26(only one being visible inFIG. 1) each of these links comprising a forward end26ajoined to the fan case18, for example on or close to a horizontal median plane of the gas turbine engine6.

The aft portion of this thrust load device14will now be described with reference toFIGS. 2 and 3.

In these figures, it can be seen that the two side links26, arranged either side of the vertical, longitudinal median plane24of the mounting structure, also corresponding to a vertical median plane of the gas turbine engine, each have an aft end26bconnected to an evener bar28, as will be detailed below.

The evener bar28is coupled to a hinge pin32, preferably of dual pin type, positioned so that the longitudinal vertical median pane24passes through it. This hinge pin of the evener bar therefore passes through an orifice34made in the evener bar28itself, and through a clevis36whose two sides are arranged either side of the evener bar28, this clevis36belonging to a connecting bracket38to the rigid structure.

More precisely, to ensure a so-called Fail-Safe function, the evener bar28preferably consists of two superimposed brackets28a,28bas shownFIG. 2, the above-mentioned orifice34therefore being jointly defined by the two orifices34a,34bprovided on brackets28a,28brespectively.

The connecting bracket38has one aft end fixedly attached underneath the lower spar17with which it is preferably in contact, the assembly means used (not shown) of bolt type for example cooperating with a reinforcement bracket40housed inside the box, and preferably being in contact with the inner surface of the lower spar17. In this respect, provision may be made for this reinforcement bracket40to have two side walls42intended to be respectively attached to two fins (not shown) of the lower spar17of the box, its lower sidewall therefore following the contour of the inner surface of this same lower spar17. Therefore the reinforcement bracket40is similar to the transverse ribs of the box, with the difference that it does not extend over the entire height of the rigid structure.

To ensure the assembly of the aft end26bof each link26, a mechanical connection44is provided forming the connection via which thrust loads are intended to be normally transmitted. It essentially consists of a lug48provided on the associated side end of the evener bar28, this lug48having the particular aspect of extending substantially cross-wise relative to the device14, namely substantially in direction Y even if it may lie at a slight angle to this direction, as will be described below. In this respect, provision is made so that the lug extends preferably orthogonally relative to the axis of the side link26through which it passes.

Here again, owing to the dual nature of the bracket used to form the evener bar28, each of the two lugs48is preferably defined by two semi-cylinders48a,48brespectively belonging to brackets28a,28band lying in contact with one another along their diametrical face. Each lug48is effectively preferably provided with a circular section and optionally comprises an extension of smaller section to receive the securing means (not shown) as can be seenFIGS. 2 and 3.

The lug48enters into the orifice50provided on the aft end26bof the thrust link26concerned, the axis of this orifice then substantially merging with the axis of the above-mentioned lug48. Also, a ball joint52is provided between the orifice50and the lug48, this lug passing through an inner ring of the ball joint, whilst the outer ring thereof is housed fixedly in orifice50.

With reference now toFIGS. 4ato4c, it can be seen that each pin48can be oriented not only along direction Y, but also alternatively it can lie slightly at an angle thereto, the objective being to maintain a substantially transverse orientation for these lugs at all times, so that the mounting of the associated mechanical connection44remains easy without any risk of deteriorating the engine assembly1. Additionally, it is preferably sought to give the lug an orthogonal direction relative to the axis of the thrust link26through which it passes.

Therefore, as shownFIG. 4a, provision may be made so that each lug48extends along an axis60lying in a solid angle62in the form of a cone of revolution whose central axis64corresponds to direction Y, the value of this solid angle62then being equal to or less than 2π·(1−cos(15°)) sr.

Also, with reference toFIG. 4b, provision is made so that from an overhead view such as shown, each lug48extends along an axis60forming an angle66having a value equal to or less than 15° with the transverse direction Y. Similarly provision is made so that from a front view such as shownFIG. 4c, each lug48extends along an axis60forming an angle68of value equal to or less than 15° with the transverse direction Y.

At all events, as shownFIGS. 4ato4c, provision is preferably made so that each lug48extends slightly aftward away from the centre of the thrust load device, and optionally so that each lug48extends slightly upward away from the centre of this same thrust load device.

Again with reference toFIGS. 2 and 3, it can be seen that the thrust load device14also comprises an abutment bracket70that is horse-shoe shaped, which is arranged at a forward central portion of a clevis72through which the hinge pin32also passes. More precisely, the two sidewalls of this clevis72are arranged either side of the evener bar28and more specifically are each inserted between this evener bar28and one of the two sidewalls of the clevis36of the connecting bracket38.

The horseshoe-shaped abutment bracket70, preferably arranged so that the median plane24passes symmetrically through it, comprises two free ends substantially oriented aftwardly, each one being fixed to the box in similar manner to the connecting bracket38, namely by following the outer contour of the lower spar17and being assembled thereto via conventional assembly means (not shown) cooperating with the reinforcement bracket40.

In addition, the abutment bracket70has an abutment surface74lying aftward relative to the evener bar28, and being more precisely defined at the bottom part of the above-mentioned clevis72. It is designed so that it can, in both directions, stop rotation of the evener bar about its hinge pin32.

The abutment surface74, which may optionally consist of two separate surfaces arranged symmetrically relative to the vertical median plane24as shownFIG. 2, is effectively positioned judiciously so that in the event of failure of the thrust load device14, possibly occurring as rupture of one of the thrust links26or rupture of one of the two connections44, the rotation of the evener bar28is stopped by this surface74. It is to be noted that under normal operation this abutment surface74evidently remains inactive, since the evener bar28then lies away from it.

Therefore, when failure of the above-mentioned type occurs, the evener bar28which is then only connected via a single thrust link26, pivots about its hinge pin32until one of its side ends contacts the abutment surface74lying in the vicinity. It is therefore to be appreciated that the positioning of the abutment surface74is chosen so as to impose a maximum angle of rotation of this evener bar about the hinge pin32, this maximum angle preferably being identical for both directions of rotation and evidently being determined so that the thrust load transmitting function is able to be ensured by the thrust load device14at least for a determined time.

With said arrangement, as can be schematically seenFIG. 5, the forward engine attachment10attached to point P1is designed so as to transmit loads exerted chiefly in the vertical direction Z, and also in the transverse direction Y, but is not adapted to transmit loads exerted in the longitudinal direction X.

The aft engine attachment12is designed to transmit loads chiefly exerted in the transverse direction Y, and its chosen design is preferably of a known type called “semi-attachment” type enabling each of the two semi-attachments (not shown) to transmit the loads exerted chiefly in the vertical direction Z. The aft attachment is additionally capable of ensuring transmittal of the moment exerted in direction X.

Finally, the thrust load device14is able to transmit loads exerted chiefly in the longitudinal direction X.

In this way, the loads exerted along the longitudinal direction X are solely transmitted by the thrust load device, the loads exerted in the transverse direction Y are jointly transmitted by the forward10and aft12attachments, and the loads exerted in the vertical direction Z are also jointly transmitted by the forward attachment10and the two semi-attachments of the aft attachment12.

Also, transmitting of the moment exerted in direction X is ensured solely by the two semi-attachments of the aft attachment12, whilst transmitting of the moments exerted in directions Y and Z is jointly ensured by these two engine attachments10,12.

With reference toFIGS. 6ato6e, different successive steps are illustrated of an assembly method for the mounting structure14, the views globally being underside views.

First, with reference toFIG. 6a, it can be seen that one of the specificities of the method lies in the fact that, prior to mounting the aft ends of the thrust links onto their respective associated lugs, the evener bar28has already been fixed to the rigid structure8via the connecting bracket38. Evidently, before starting to engage the aft end26bof the first link26onto its associated lug48such as shownFIG. 6b, the engine is suitably positioned relative to the rigid structure8of the pylon.

As mentioned previously, the engaging of the aft end26bof the thrust link26can be made by a mere substantially lateral movement of the link lying close to the lug concerned. Also, since the front end26aof the thrust link26is already mounted on the engine, this movement can roughly be compared to slight rotation of the thrust link about its front end26a, so as to achieve full engagement of the aft end26bonto the lug48, as shownFIG. 6c.

Next, the same operations are carried out for the other thrust link26, such as shownFIGS. 6dand6e, although the mounting of the two links26could evidently be performed simultaneously without departing from the scope of the invention.

Evidently, various modifications could be made by persons skilled in the art to the mounting structure4and engine assembly1just described solely as non-limiting examples. In this respect, it can notably be indicated that while the engine assembly1has been presented in a configuration adapted for mounting below the aircraft wing, this assembly1could also have a different configuration allowing it to be mounted above this same wing, even on an aft portion of the fuselage of this aircraft.