The present invention relates to a suspension system for two modules, such as two fan modules, of a propulsion unit, in particular of an aircraft.
The prior art notably comprises documents EP-A2-1 916 406, US-A1-2015/274306 and US-A1-2005/067528.
The applicant has undertaken work on a propulsion unit architecture with at least two distributed fans. The aim was to achieve optimization of the propulsive efficiency owing to a high by-pass ratio, while maintaining acceptable ground clearance and fans of reduced size.
A schematic diagram of said unit 10 is shown in
It is known to suspend a propulsion unit on a structural element of an aircraft, by means of a pylon. For the particular architecture mentioned in the foregoing, the applicant chose to suspend the propulsion unit with two fans on a single pylon.
However, mounting two fan modules on a single pylon requires the two modules to generate the same thrust. In this configuration, the pylon is mounted mid-way between the modules, the plane of symmetry of the pylon being perpendicular to the plane containing the axes of the fans, and located equidistantly from these axes.
Now, in production, there is a potential deviation of a few percent on the thrust of two fan modules. Moreover, there are fan designs where the thrusts are different deliberately. In both of the aforementioned cases, two different thrusts generate a torque on the pylon, which requires the pylon to be overdimensioned so that it has sufficient fatigue strength and static strength. This has a significant effect on the weight of the pylon and therefore of the suspension system for the propulsion unit.
To solve this torque problem, it would be possible to position the pylon in the vertical plane passing through the centre of gravity of the propulsion unit (
Another solution would be to position the pylon 28 in the vertical plane passing through the centre of gravity of the propulsion unit, and use an asymmetric crossbar 30 so that L·P=L′·P′ where P and P′ denote the respective thrusts of the modules and L and L′ are the distances from the axes of the modules 26, 26′ to the pylon 28 (
However, these two solutions are not entirely satisfactory as they are difficult to adapt to different configurations. If a module is changed, or there is variation in thrust or failure of a module, these solutions are incapable of limiting the displacements of the modules.
The present invention proposes a solution to the aforementioned need, which is simple, effective and economical.
The invention proposes a suspension system for two modules of a propulsion unit, such as two fan modules, comprising a pylon, a crossbar one part of which is hinged on said pylon and opposite ends are hinged on link rods, characterized in that it further comprises a torque reaction bar, said bar being of elongated shape and mounted swivelling on said pylon about an axis approximately parallel to an extension axis of said bar, opposite ends of said bar being fixed to said crossbar, on either side of said portion of the latter.
The torque reaction bar makes it possible to limit the relative displacements between the modules, simplify the integration of the propulsion unit (reduction in the size of the joints between the pods of the modules and between the pods and the pylon, reduction of the assembly clearances and of the main frame of the pods, etc.), and limit the stresses on the pods (potential increase in weight). The system according to the invention may be used for suspending two fan modules of a propulsion unit or other types of modules, such as two engines or gas generators, of a propulsion unit.
The system according to the invention may comprise one or more of the following features, taken separately from one another or in combination with one another:
The present invention also relates to a propulsion unit, comprising a gas generator and at least two fan modules, characterized in that it is equipped with a system as described above, said link rods being hinged respectively on said fan modules.
The invention will be better understood and other details, features and advantages of the invention will become clearer on reading the following description provided as a non-limiting example and referring to the appended drawings, in which:
In the case when the propulsion unit comprises two fan modules, as shown in
The system 32 essentially comprises a pylon 28, a crossbar 30, thrust-reacting link rods 34, 36, and a torque reaction bar 40.
The pylon 28 has an elongated shape and one of its longitudinal ends is in this case hinged on a portion 30′ of the crossbar 30, which is either a middle portion of the crossbar or some other portion of the crossbar as is the case in the example shown. This portion 30′ takes up the thrust forces of the two fan modules.
The crossbar 30 also has an elongated shape with an extension axis designated A. Each of its longitudinal ends is hinged on one end of at least one link rod 34, 36, whose opposite end is intended to be hinged on one of the fan modules.
The portion 30′ of the crossbar 30 is located at a distance D1 from the end of the crossbar 30 connected to the link rod 34, and at a distance D2 from the opposite end of the crossbar 30 connected to the link rod 36. In the example shown, D1 is greater than D2. The means 38 for articulation of the pylon 28 to the crossbar 30 and of the crossbar to the link rods 34, 36 are preferably of the swivel type.
The torque reaction bar 40 has an elongated shape whose extension axis is designated B and is substantially parallel to the axis A.
The bar 40 is fixed rigidly to the crossbar 30 and is mounted by a swivel joint on the pylon 28. The bar 40 extends in the vicinity of the crossbar 30 and here it has a length L2 less than that L1 of the crossbar 30. The longitudinal ends 42 of the bar 40 are fixed on the crossbar 30 on either side of the portion 30′, and near the ends of the crossbar 30 in the example shown. Preferably, but in a non-limiting manner, the rigid link between the crossbar 30 and the bar 40 is made by means of a male-female joint. In particular, as is illustrated in
The pylon 28 comprises two arms 44 for supporting and mounting the bar 40. Each arm 44 comprises a hole 46 for passage of the bar 40 and guidance in rotation about the axis B. In the case when the bar 40 is of a cylindrical shape, each arm 44 could comprise a tubular portion 48 defining a cylindrical internal surface for guiding the corresponding arm, as can be seen in the more concrete example in
In the embodiment in
Each link rod 34, 36 hinged on a fan module may be offset (not parallel) relative to the axis of the gas generator. The offset angle may be between 5 and 15°.
From now on reference will be made to
As is shown in
For this purpose, the torque reaction bar 40 is made of high-alloy steel so as to take up the forces. Some other material additionally comprising properties of heat resistance may of course be used for making the bar 40.
A propulsion unit with fan modules with different thrust may thus be suspended without technical difficulty on a structural element of the aircraft.
Number | Date | Country | Kind |
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15 59451 | Oct 2015 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2016/052387 | 9/21/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/060581 | 4/13/2017 | WO | A |
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Number | Date | Country | |
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20180281980 A1 | Oct 2018 | US |