Multi-material torque transmission part comprising a polygonal fitting, landing gear and aircraft comprising such a part

Abstract

A torque transmission part (1) comprising a tubular body (2) and a toothed ring gear (4) carried by the body (2), wherein the ring gear and the body are made of different materials, the ring gear is rotationally connected to the body by a polygonal connection, and the polygonal connection comprises a convex n-sided polygon.

Description

[0001] MULTI-MATERIAL TORQUE TRANSMISSION PART INCLUDING A POLYGONAL ENGINE LANDING AND AIRCRAFT INCLUDING SUCH A PART.

[0002] The present invention relates to the field of force transmission parts and more particularly to torque transmission parts.

[0003] BACKGROUND OF THE INVENTION

[0004] In the aeronautics sector, optimizing component mass is a major challenge, directly linked to reducing fuel consumption and, consequently, the environmental footprint of aircraft. Within an aircraft, landing gear represents a significant portion of the total weight. Therefore, any reduction in the weight of this structure would improve the aircraft's energy efficiency while reducing greenhouse gas emissions.

[0005] To reduce the weight of technical parts, it is well known to favor the use of lighter materials. However, for parts subjected to high mechanical stresses, such as aircraft landing gear supporting tens of tons, it is essential to ensure that the weight reduction does not lead to a reduction in the mechanical strength of these parts.

[0006] A landing gear typically comprises a leg with a box section and a rod that slides and rotates within the box section. The rod has one end extending beyond the box section and carrying wheels. The box section has a first end connected to the aircraft structure and a second end from which the rod protrudes. Front landing gears are generally equipped with a steering mechanism comprising a rotating tube mounted to pivot on the second end of the box section and connected to the rod by a compass, such that the rotation of the rotating tube causes the rotation of the rod. The rotation of the rotating tube is generally achieved by an actuator moving a pinion or rack that meshes with teeth machined into the outer surface of the rotating tube. Such a rotating tube is illustrated in perspective in Figure 1.

[0007] As the teeth are subjected to high stresses, particularly in terms of hardness and stiffness, the rotating tube is generally made of steel and it is not feasible, given these stresses, to use a lighter material.

[0008] SUBJECT OF THE INVENTION

[0009] The invention aims in particular to provide a mechanical device to remedy at least partially the aforementioned drawbacks.

[0010] SUMMARY OF THE INVENTION

[0011] For this purpose, according to the invention, a torque transmission part is provided, comprising a tubular body and a toothed ring carried by the body, the ring and the body being made of different materials, the ring is rotationally linked to the body by a polygonal linkage, and the polygonal linkage comprises a convex polygon of type PnC.

[0012] Thus, the transmission component combines the technical advantages of the two different materials that make up the toothed ring and the body, respectively. These two materials have different physical properties, such as density and hardness. The polygonal joint, which transmits the rotational forces between the ring and the body, takes the form of a convex polygon of the PnC type. It has several sides (n in the PnC designation), and these sides are connected by rounded edges rather than sharp angles. This provides precise contact between the two parts, minimizing the stress concentration and weakness areas that angles can present. This shape allows for a uniform distribution of torque, while preventing slippage or excessive wear of the contacting parts, even if they are made of materials with different hardnesses.By allowing such an assembly, the invention makes it possible to optimize the production of each part to improve the performance of the assembly, particularly in terms of mass and / or cost and / or industrialization.

[0013] Depending on optional features, used individually or in whole or in combination:

[0014] - the polygon is of type P4C;

[0015] - the crown material has a higher hardness than the body material;

[0016] - the crown material has a higher density than the body material;

[0017] - the connection includes an axial locking means;

[0018] - the toothed crown is mounted tightly on the body;

[0019] the body is obtained through an additive manufacturing process.

[0020] The invention also relates to an aircraft directional landing gear, comprising a telescopic leg having a rotating fixed section provided with means for connecting said fixed section to an aircraft and a pivoting section having a free end provided with an axle carrying a rotating wheel, a rotating tube cooperating by meshing with a slewing actuator being pivotally mounted on the rotating fixed section and being connected to the pivoting section by a compass so as to be rotationally fixed to the pivoting section, the rotating tube being formed of a single piece according to the invention, the toothed ring cooperating by meshing with the slewing actuator and the compass having an end articulated to the tubular body. The invention also relates to an aircraft equipped with such a landing gear. Other features and advantages of the invention will become apparent from the following description of a particular and non-limiting embodiment of the invention.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Reference will be made to the attached drawings, including:

[0023] [Fig. 1] is a perspective and transparency view of a lander comprising a rotating tube according to the prior art;

[0024] [Fig. 2] is an elevational view of an aircraft equipped with landing gear according to the invention;

[0025] [Fig. 3] is a perspective view of the torque transmission part according to the invention;

[0026] [Fig. 4] is a representation of a P4C type polygon corresponding to the shape of the transmission polygon present in the invention;

[0027] [Fig. 5] is a partial perspective view of the lander's leg, showing more particularly the torque transmission part according to the invention;

[0028] [Fig. 6] is a perspective diagram of a lander comprising the invention.

[0029] DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1, the invention is described in application to an aircraft 100 comprising main landing gear each having a leg 101 having a first end 101.1 articulated to a structure of the aircraft 100, and opposite it, a second free end 101.2 provided with an axle 102 on which wheels 103 are pivotally mounted.

[0030] We are particularly interested in the forward landing gear, which is directional, of this aircraft. Leg 101 of this landing gear is telescopic, has a substantially cylindrical shape and extends with respect to a principal axis X.

[0031] The leg 101 comprises a fixed rotating section or box 104 provided with a joint linked to the aircraft 100 at the first end 101.1 of the 'lander 101', and a pivoting section or rod 105, mounted to slide and pivot in the box 104 with a free end projecting from the box 104 to form the second end 101.2 of the leg 101.

[0032] A transmission part 1 is mounted on the 104 box for rotation.

[0033] The transmission part 1 has a tubular body 2 extending along the main axis X, comprising a first end 2.1, a second end 2.2, as well as an external surface 2.3 and an internal surface 2.4 delimiting a cylindrical volume 2.5.

[0034] The tubular body 1 is rotationally mounted on a cylindrical section 104.1 belonging to the box 104 of the leg 101, the section 104.1 extending into the cylindrical volume 2.5.

[0035] On the external surface 2.3 of the body 2 of the transmission part 1, at the level of the second end 2.2, a bearing 3 extends radially.

[0036] Bearing 3 has a bore 3.1 through it along a secondary Y axis perpendicular to the main X axis and substantially tangent to the external surface 2.3 of body 2.

[0037] This bearing 3, thanks to its hole 3.1, is arranged to accommodate a U-shaped end 106.1 of a compass 106. The compass 106 is conventional and comprises an upper part whose end 106.1 is articulated to the box 104 and a lower part articulated to the upper part on one side and to the rod 105 on the other to link in rotation around the main axis X the body 2 and the rod 105 while allowing the rod 105 to slide in the box 104.

[0038] The end 106.1 of the compass 106 comprises two arms 106.2 which extend opposite each other and which carry a cylindrical shaft 106.3. Once assembled, the cylindrical shaft 106.3 extends into the bore 3.1. The cylindrical shaft 106.3 connected to the compass 106 and the bearing 3 connected to the body 2 form a joint with one degree of freedom in rotation about the Y axis.

[0039] Thus, the transmission part 1 is linked to the rod 105 by the compass 106 to be fixed to the rod 105 in rotation with respect to the X axis.

[0040] The transmission part 1 also includes a ring 4, comprising an outer contour 4.1, an inner contour 4.2 and two annular end faces 4.3 and 4.4.

[0041] The crown 4 also has relief pockets 5 hollowed axially in the crown 4 from the annular faces 4.3 and 4.4.

[0042] The outer rim 4.1 of the crown 4 is circular and includes transmission teeth 4.5. The teeth 4.5 are straight here.

[0043] The inner perimeter 4.2 of the ring 4 has a polygonal shape. This polygonal shape is a P4C type polygon (a four-sided polygon with curves). This shape, illustrated in Figure 4, is generally square, with four principal sides of equal length and parallel in pairs, but which has circular arcs or fillets instead of right angles. The body 2 has, at its first endpoint 2.1, a segment of the external surface 2.3 having a cross-section of a P4C type polygon with dimensions corresponding to those of the inner perimeter 4.2 of the ring 4.

[0044] The ring 4 and the body 2 are thus assembled to form the transmission part 1, by inserting the end 2.1 into the inner circumference 4.2 of the ring 4 to form a polygonal joint. Torque forces are transmitted between the ring 4 and the body 3 via this polygonal joint. The P4C type polygonal joint is advantageous for torque transmission because each side of the polygon provides precise contact, minimizing potential weak points at angles, and allowing for a uniform distribution of torque across all contact surfaces, while preventing rotational slippage of the ring 4 relative to the body 3 and excessive wear on both.

[0045] The body 2 has on its external surface 2.3 studs 2.6 comprising radial holes 2.7 forming access points to allow lubrication of the system.

[0046] The body 2 preferably includes an axial locking means 6 for the ring 4, enabling the ring 4 to be held in position on the body 2 along the principal axis X. This locking means 6 includes at least one tapped hole radially passing through the body 2 from the inner surface 2.4 of the body 2 to the outer surface 2.3, and a screw 6.1 applying a buttress against the inner periphery 4.2 of the ring 4. The screw 6.1 is a headless screw or, failing that, the hole includes a chamfer or counterbore for countersinking the screw head.

[0047] It is envisaged that the dimensioning tolerances of polygon P4C of the ring gear 4 and the body 2 will be chosen so that said ring gear 4 is press-fitted onto the body 2. This mounting characteristic may require assembly involving a thermal process (the body 2 is cooled here with liquid nitrogen while the ring gear 4 is heated). Such a press-fit assembly limits slippage between the ring gear 4 and the body 2, as friction generates wear and stresses that are damaging to the parts (there would be a localized overload at the contact point due to friction if present). The screw 6.1 secures the assembly if necessary, orients the teeth, and ensures the position during the hot assembly of the two parts. The press fit is particularly effective in ensuring the transmission of forces between the two parts. It is envisaged that the body 2 and the ring gear 4 will be made of two different materials.The body 2 is made of a material with advantageous lightweight characteristics, and the crown 4 is made of a material with significant mechanical strength characteristics. For example, the body 2 may be made of a lightweight alloy, and the crown 4 may be made of a heavier alloy, but one with high hardness, stiffness, fatigue resistance, and resilience.

[0048] In this configuration, the transmission part 1 combines the technical advantages of a lightweight part thanks to the body 4, and a part strong enough to transmit significant forces thanks to the ring 4. This feature reduces the overall mass of the transmission part 1, while maintaining the ability to transmit significant forces.

[0049] It is also envisaged that body 2 will be manufactured using an additive manufacturing process. Additive manufacturing allows for the design of a complex shape, which may include hollow parts, thus promoting the structural lightening of said part.

[0050] Assembled in the landing gear, the transmission component 1 transmits rotational motion from a steering actuator 7 to the rod 105 and the wheels 103 of the landing gear. To achieve this, the steering actuator 7 includes a pinion 7.1 that can be rotated and is controlled from the cockpit of the aircraft 100. The pinion 7.1 has teeth 7.2 that mesh with the teeth 4.5 of the ring gear 4, thus transmitting torque between the pinion 7.1 of the actuator 7 and the ring gear 4. The polygonal linkage, in turn, transmits this torque from the ring gear 4 to the body 2, causing the entire transmission component 1 to rotate. Finally, the linkage between the transmission component 1 and the compass 106 transmits this rotation to the rod 105 and the wheels 103.

[0051] The rotation control of the wheels 103 around the X-axis allows pilots to perform maneuvers with the aircraft 100 while it is taxiing on the ground, such as taxiing or parking maneuvers. Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0052] In particular, although the teeth on the ring gear 4 and pinion 7.1 are straight here, they could be of a different shape, for example helical or herringbone. The steering actuator may include a linear actuator moving a rack.

[0053] Although here the polygonal transmission link between the body 2 and the toothed ring 4 is a convex polygon preferably comprising at least four principal sides, here more precisely of type P4C, it is envisaged that this polygon may have a different number of sides, and for example a triangular polygon P3C. These polygons are of type PnC where n is the number of sides of the polygon.

[0054] Although the main sides of the polygonal joint are straight in the figures, they may exhibit a slight curvature, specifically a convex curvature. Preferably, the sides of the polygon are defined according to the formula described in DIN 32712. This mathematical formula allows for the plotting of a curvature with a specific profile (in polar or Cartesian coordinates). However, other curves that yield a convex polygonal profile are also compatible with the invention.

[0055] It is envisaged that the body 2 of the transmission part designed by an additive manufacturing method, has a shape modified by topological optimization, to optimize the mass / stiffness ratio.

[0056] The invention is particularly well suited to assemblies with an added toothed sector, the mass and / or cost and / or industrialization of which must be optimized.

[0057] However, transmission part 1 can be adapted to be compatible with any kind of mechanism requiring a transmission part.

[0058] The materials of the crown and the body may have different mechanical characteristics other than density and hardness.

[0059] Axial locking is an option that is added if the design requires it. Mounting without axial locking, or with axial locking in only one direction, is also possible.

Claims

DEMANDS 1. Torque transmission part (1), comprising a tubular body (2) and a toothed ring (4) carried by the body (2), characterized in that the ring and the body are made of different materials, in that the ring is rotationally connected to the body by a polygonal joint, and in that the polygonal joint comprises a convex polygon of type PnC.

2. Part according to claim 1, wherein the convex polygon is of type P4C.

3. Part according to claim 1 or 2, in which the material of the crown (4) has a greater hardness than the material of the body (2).

4. Part according to any one of the preceding claims, wherein the material of the crown (4) has a higher density than the material of the body (2).

5. Part according to any one of the preceding claims, wherein the polygonal connection includes an axial locking means (6).

6. Part according to any one of the preceding claims, in which the toothed ring (4) is mounted tightly on the body (2).

7. Part according to any one of the preceding claims, in which the body (2) is obtained by an additive manufacturing process.

8. Aircraft directional landing gear, comprising a telescopic leg (101) having a rotating fixed section (104) provided with a means for connecting said fixed section to an aircraft (100) and a pivoting section (105) having a free end (101.2) provided with an axle carrying a rotating wheel (103), a rotating tube cooperating by meshing with a slewing actuator (7) being pivotally mounted on the rotating fixed section and being connected to the pivoting section by a compass (106) to be rotationally fixed to the pivoting section, characterized in that the rotating tube is formed of a piece according to any one of the preceding claims, the toothed ring cooperating by meshing with the slewing actuator and the compass having an end articulated to the tubular body.

9. Aircraft (100) comprising a landing gear according to claim 8.

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