Aircraft undercarriage including a telescopic linear rod

1. An aircraft undercarriage including a telescopic linear rod ( 0 , 0 ′, 0 ″) extending between a first rod end ( 30 , 30 ′, 30 ″) having means for attaching the rod to a main structure of the aircraft and a second rod end ( 31 , 31 ′, 31 ″) carrying a wheel axle ( 5 , 5 ′) of the undercarriage, the telescopic linear rod ( 0 , 0 ′, 0 ″) comprising rod portions ( 1 , 2 , 3 , 4 , 1 ′, 2 ′, 3 ′, 4 ′, 1 ″, 2 ″, 3 ″, 4 ″) adapted to slide in one another along a main axis of symmetry (X-X, X′-X′, X″-X″) of the rod in order to extend or retract the telescopic rod, the undercarriage comprising:

a first permanent magnet set ( 1 a , 1 a ′, 1 a ″) fastened to a first of said rod portions ( 1 , 1 ′, 1 ″); and

a second permanent magnet set ( 2 a , 2 a ′, 2 a ″) fastened to a second of said rod portions ( 2 , 2 ′, 2 ″);

the first and second permanent magnet sets ( 1 a , 1 a ′, 1 a ″, 2 a , 2 a ′, 2 a ″) are arranged so as to generate a magnetic repulsion force between the first rod portion ( 1 , 1 ′, 1 ″) and the second rod portion ( 2 , 2 ′, 2 ″) and to maintain a first annular space (E 1 ) extending around one of the first or second rod portions and situated between the first rod portion and the second rod portion;

at least some of the magnets of the first permanent magnet set ( 1 a , 1 a ′, 1 a ″) are:

arranged facing at least some of the magnets of the second permanent magnet set ( 2 a , 2 a ′, 2 a ″) so as to generate magnetic torque opposing relative pivoting about the main axis of symmetry (X-X, X′-X′, X″-X″) of the first rod portion ( 1 , 1 ′, 1 ″) relative to the second rod portion ( 2 , 2 ′, 2 ″); and

arranged to form branches of a star extending around the main axis of symmetry (X-X, X′-X′, X″-X″); and wherein

at least some of the magnets of the second permanent magnet set ( 2 a , 2 a ′, 2 a ″) are arranged between some of the branches of the star to generate magnetic repulsion forces against the magnets of the first permanent magnet set forming the branches of the star.

2. The undercarriage according to claim 1 , wherein each of the magnets of the first permanent magnet set ( 1 a , 1 a ′, 1 a ″) is incorporated in the first rod portion ( 1 , 1 ′, 1 ″) and each of the magnets of the second permanent magnet set ( 2 a , 2 a ′, 2 a ″) is incorporated in the second rod portion ( 2 , 2 ′, 2 ″).

3. The undercarriage according to claim 1 , wherein the telescopic linear rod further comprises at least one first electromagnet ( 1 b , 1 b ′, 1 b ″) that generates a first axial repulsion force opposing relative approach between the first and second rod portions ( 1 , 2 , 1 ′, 2 ′, 1 ″, 2 ″) along a direction parallel to said main axis of symmetry (X-X, X′-X′, X″-X″) of the rod.

4. The undercarriage according to claim 3 , further comprising electrical power supply means for powering said at least one first electromagnet, the power supply means is arranged to vary the electrical power supplied to said at least one first electromagnet so as to control relative sliding between said first and second rod portions.

5. The undercarriage according to claim 4 , wherein said power supply means are adapted to control at least one first electromagnet ( 1 b , 1 b ′, 1 b ″):

to extend or retract the telescopic linear rod by relative sliding between said first and second rod portions; and

to vary the damping characteristics of the relative movement between said first and second rod portions.

6. The undercarriage according to claim 4 , wherein said at least one first electromagnet ( 1 b , 1 b ′, 1 b ″) is assembled to one end of the first rod portion ( 1 , 1 ′, 1 ″), and the undercarriage further comprises a second electromagnet ( 2 b , 2 b ′, 2 b ″) assembled to one end of the second rod portion ( 2 , 2 ′, 2 ″), these first and second electromagnets being are placed facing each other and act together to generate said axial repulsion force opposing said relative approach between the first and second rod portions.

7. The undercarriage according to claim 1 , including at least one rotation-control electromagnet ( 10 ″, 20 ″) arranged to control rotation about said main axis of symmetry (X″-X″) of at least some of the first and second rod portions ( 1 ″, 2 ″, 3 ″, 4 ″) relative to the means attaching the rod to the main structure of the aircraft.

8. The undercarriage according to claim 7 , wherein a set of rotation permanent magnets ( 40 ″) is arranged to co-operate with said at least one rotation-control electromagnet ( 10 ″) to control said rotation, said set of rotation permanent magnets is placeable facing magnetic poles of said at least one rotation-control electromagnet ( 10 ″) and is capable of assembly to a stationary casing ( 41 ″) surrounding the telescopic rod ( 0 ″) over at least a fraction of a length of said rod.