Patent Application
20110296676
The present invention relates to a system for attaching two components together, including an aircraft engine and an engine mounting pylon integral with the structure (wing or fuselage) of the aircraft, and with a view to treating, at least partially, even completely, the vibrational phenomena generated by the operation of the engines.
It is known that the junctions between the engine(s) and the mounting pylons are achieved by attaching systems of the front and rear trunnion type, inter alia arranged according to the longitudinal axis of the engine and contained in planes being perpendicular to said longitudinal axis.
In airliners provided with turbojets, the trunnions of the attaching systems are rigid taking up stresses and torque issued from engines. In addition, with such trunnions, vibrations generated by the latter propagate up to the fuselage inside which the crew and passengers are located. However, thanks to the elasticity inherent to the wings, vibrations are essentially filtered, so that vibrations are hardly experienced by passengers and the crew and thus acceptable. Nevertheless, such vibrations exist and could, in the end, cause a structural wear of some parts and be amplified mainly at particular frequency ranges and become a nuisance for passengers and crew members.
If vibrational problems on turbojet airplanes are less obvious, although present, on the other hand, on airplanes provided with turbopropellers, the vibrations are amplified, in particular, at low frequencies, all the more as, in some airplanes designs, the turbopropellers are directly mounted in the wings.
In order to overcome such vibrational phenomena, the trunnions of attaching systems use elastomers so that the latter are less rigid but have a more significant damping than rigid trunnions, allowing for a partial filtration of vibrations, but nevertheless unsatisfactory at low frequency. Indeed, such “flexible” trunnions are submitted to high static loads, involving a high rigidity, in order to limit the movements and the “flutter” phenomena. A high rigidity directly results in a high resonance frequency (depending on the mass as well).
Dampers could also be provided on the attaching systems between the engine and the structure. However, the use thereof does not allow to act on the vibration modes, but to attenuate the effects thereof. In order to be efficient, a damper requires a minimum of movement speed. The current vibrations do not allow such a kind of implantation.
The present invention aims at overcoming such drawbacks and relates to a system for attaching two components together such as an aircraft engine to its mounting pylon, the design of which allows to efficiently counteract the transmission of vibrations and efforts associated with the engine toward the structure of the aircraft, to filter the efforts issued from the engine whether of the turbopropeller, turbojet type or other, so as to reduce the vibrational levels toward the structure of the aircraft, and not to alter the latter nor the comfort of passengers and crew members.
To this end, the system for attaching two components together, such as an aircraft engine and a mounting pylon of said engine integral with the structure of said aircraft, of the type comprising, in particular, front trunnions and rear trunnions with respect to the longitudinal axis X of said engine according to an orthonormal reference point XYZ, and contained in planes YZ perpendicular to said axis X, is remarkable according to the invention:
Thus, thanks to this invention, the associated vibrations and efforts resulting from the operation of the engine and transmitted by the shackles to the suspension assemblies are taken up by the elastic elements, the deformation of which causes the suspension assemblies being rotated and the associated resonant masses located at the opposite of the elastic elements, being driven. At a defined excitation frequency, the mass assemblies, acting as resonators, become anti-resonant while counteracting the vibrational phenomena.
Consequently, as opposed to rigid systems allowing vibrations to be transmitted or to elastomer systems absorbing some vibrations, the system of this invention filters the efforts and all the vibrations generated by the integrated resonator suspension assemblies producing a frequency opposed to that of the elastic elements, while ensuring the attaching rigidity of the engine on the pylon.
According to a preferred embodiment, the two shackles of said trunnions are arranged approximately according to directions parallel to the axis Y and symetrically to the axis X and a third rigid trunnion is provided between said pylon and said engine and comprises a shackle jointed to them and arranged approximately according to a direction parallel to the axis Z.
Thus, the efforts according to Y and the torque around X are taken up by the shackles of the assemblies, whereas the efforts according to Z are taken up by the shackle of the third trunnion.
Preferably all said three trunnions are front trunnions of said engine on said pylon. However, all said three trunnions could be rear trunnions of said engine on said pylon.
Advantageously, each suspension assembly could have the shape of an arm being bent according to the periphery of said engine and bearing, at its ends, said elastic element and said resonant mass, whereas said jointing axis of said arm to said pylon is located in the vicinity of said elastic element. Thus, the mass is remote at most from the elastic element and at a defined excitation frequency, the arm and the mass of each assembly then form a substantial and efficient resonator becoming anti-resonant, thereby protecting the structure of the airplane from vibrations.
In order to increase the distance between the elastic element and the mass of each arm and to thereby limit the weight of the latter, the bent arm of each assembly could extend around said engine on about half of its periphery and tapers in the direction of its free end.
Furthermore, said jointing axes parallel between said assemblies and said pylon, said shackles and said engine, and said shackles and said assemblies are provided with flexible bearings made of an elastomer or similar. Such an arrangement does not create any friction between the different links so that the vibrations are able to be transmitted “freely” for being absorbed by the suspension assemblies of the attaching system.
In a preferred embodiment, said elastic element of each suspension assembly comprises at least one spring arranged on said pylon and on said assembly by respective supporting plates arranged laterally along said spring and integrating corresponding spiral portions of the latter.
As far as said resonant mass is concerned, it could have the shape of a mass roller mounted on an axis at the end of said free end of each assembly. The manufacturing simplicity and reliability of the elastic element and the resonant mass should be noticed.
Thus, taking into account the large diametral dimension of the engine and the arrangement of the shackles in directions Y for efforts to be taken up according to the latter, respective return small rods are provided, being jointed to said shackles and said suspension assemblies.
According to another feature of the attaching system, a third vibrational damping trunnion, identical to the two other trunnions, could be arranged between said pylon and said engine, so that all said three trunnions are distributed around said engine while being connected on the one hand to the latter and, on the other hand, to a circular cradle surrounding said engine and attached to said pylon.
Thus, the efforts according to the directions Y and Z and the torque around the direction X are taken up by the three trunnions that can be front and rear trunnions.
The figures of the appended drawing will better explain how this invention can be implemented. In these figures, like reference numerals relate to like components.
The attaching system 1 according to the invention, shown on
Such a structure could be the wing or the fuselage of the airplane, and in the configuration as shown on
The mounting pylon 3 comprises usually and briefly a structural casing 6 covered with appropriate skins 7 and ending at the end with a rigid beam 8 according to X, with longeron spars and transversal ribs 9. On such a rigid beam 8, the engine 2 is mounted, with a longitudinal axis X via the attaching system 1.
The latter comprises, as known, front trunnions 10 connecting the body 4 of the compressor of the engine 2 at the front of the beam 8 of the pylon 3 and contained in a plane YZ, rear trunnions 11 connecting the body of the nozzle at the rear of the beam 8 of the pylon and also contained in a plane YZ, and thrust connecting rods, not shown, connecting the engine to the pylon and substantially arranged in directions parallel to X.
Thus arranged, the front trunnions 10 of the attaching system 1 take up, as will be set forth later on, the efforts issued from the engine, according to the axes Y and Z as well as the torque around the axis X, the rear trunnions 11 also taking up the efforts according to the axes Y and Z, whereas the thrust connecting rods take up the efforts according to the axis X.
According to this invention and in this exemplary embodiment, two of the front trunnions 10 of the attaching system 1 are of the vibrational damping type, this means they aim, in addition to ensuring the attachment as such, at filtering the efforts transmitted by the operation of the engine 2 and at, thereby, reducing the vibrational levels in the airplane. It can be seen, on
Structurally, each vibrational damping trunnion comprises a suspension assembly 12 connected to the pylon and having an elastic element 14 and a resonant beating mass 15, and a shackle or a connecting rod 16 arranged between the engine 2 and the suspension assembly 12. In particular, each suspension assembly 12 has the shape of a bent arm or branch 17, the extension of which substantially follows the outline of the engine and being jointed, in the vicinity of a first one 18 of its ends, to a side ear 19 of the beam 8 around an axis 20 parallel to the axis Z. Such a first end 18 is connected to the beam 8 by the elastic element 14, to be described later on, whereas the second end 21 of each arm 17 is free and bears the resonant mass 15.
It can be seen, more specifically, on
The second free ends 21 of the arms bear, as far as they are concerned, mass rollers 26 around axes 27. As each arm 17 surrounds nearly half of the external periphery of the engine, the length of the lever arm created between the joint 20 of the arm to the beam and its second free end 21 is large, so that the roller 26 can have a relatively low mass that does not excessively make heavy that of each assembly 12. Such vibrating masses, as a result of the springs being deformed, will become anti-resonant, opposing the springs.
In this recess 28 of each arm, an end is provided of the shackle 16 connecting the engine 2 to the suspension element 12 and mounted around a jointing axis 30 parallel to X and, thus, to the jointing axis 20 and close to the latter. The other end of each shackle is also jointed around an axis 31 to an anchoring tab 32 of the engine, the axis 31 being parallel to the other jointing axes 20 and 30. It should be further noticed that the position of the axes 30, 31 is such that the shackles 16 issued from the symmetrical anchoring tabs of the engine are substantially parallel to the axis Y of the reference point so as to take up, to the best, the efforts according to this axis. Because of such an arrangement inherent to the large size of the engines, there are provided, between the shackle 16 and the bent arm 17 of each suspension assembly, two identical return small rods 34 being arranged, on the one hand, on either sides of the end of the shackle around the axis 30 and, on the other hand, on either sides of the side ear 19 around the jointing axis 20. The link between the return small rods 34 and the shackles 16 is free in rotation, whereas that between the return small rods 34 and the arms 17 is integral in rotation.
It should be noticed that, between the jointing axes 20, 30, 31 and the respective components such as the arms 17, the side ears 19, the shackles 16 and the small rods 34, elastomeric rings 35 are provided, avoiding frictions in the links (joints) so as to transmit the efforts and vibrations, so that they are taken up by the elastic spring-resonant mass suspension assemblies 12.
In order to take up the efforts according to the direction of the axis Z, the attaching system 1 comprises, as shown, more specifically on
As far as the two rear trunnions 11 of the attaching system 1 are concerned, one of which is shown on
The attaching system 1 with, in this exemplary embodiment, two of the trunnions thereof of the vibrational damping type, acts as follows.
Upon the operation of the engine, during the flight of the airplane, the generated efforts are transmitted by the shackles 16 of the attaching system 1 to two symmetrical suspension assemblies 12 via small rods 34 connected, on one side, to the shackles around the axes 30 and, on the other side, to the bent arms 17 around the axes 20. Such arms transmit the efforts to the springs 23 coming in abutment or tightening on the transversal rib 9 of the casing 6. Thus, the efforts coming from the shackles 16 are taken up and filtered by the springs 23. Also, their alternate deformation leads the bent arms 17 to be rotated around the axes 20, resulting in the mass rollers 26 being located in opposition to the springs, at the free ends 21 of the arms, to be driven.
At a defined excitation frequency, each bent arm 17 and its roller 26 become anti-resonant with respect to the associated spring, and thereby isolate the engine 2 from the pylon 3. The vibrations are thereby absorbed by the suspension assemblies 12 of the attaching system 1 and do not propagate to the structure of the airplane.
Another embodiment of the attaching system 1 according to this invention is schematically shown on
In particular, each trunnion 10 comprises a shackle 16 being jointed, on the one hand, around an axis 31 to a attaching tab 32 of the body of the compressor, and on the other hand, to a substantially rectilinear arm 17 in this example, of the corresponding suspension assembly 12. Each arm 17, as in the previous embodiment, is furthermore connected, at one of its ends, to an attaching tab 52 of the craddle 51 via the elastic element 14, that, in this embodiment, is a torsional tube 53 and bears, at its other free end, the resonant beating mass 15, being, in the present case, spherical.
On the same way as previously, this attaching system 1 respectively takes up and filters the efforts and vibrations issued from the engine 2 via shackles 16 directly (the small rods not being required in the present embodiment), deformable torsional tubes 53 and resonant spherical masses 15 of the mobile arms 17.
Furthermore,
Such a craddle system 1 could also be integrated at the level of the rear trunnions 11.
Furthermore, the torsional tubes 53 could be replaced by bending blades without departing from the scope of this invention. For instance, each blade is connected at its ends to anchoring tabs of the craddle and comprises on the latter a free beating mass elongated element, counteracting the vibrations generated by the blade jointed to the corresponding shackle issued from the engine. This embodiment of the disclosed system with torsional tube or bending blade elastic elements could integrate instead that previously described with spring elastic elements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0806867 | Dec 2008 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR2009/052364 | 12/2/2009 | WO | 00 | 6/28/2011 |
