Antivibration device having rotary flyweights and an epicyclic geartrain

1. An antivibration device (D) for reducing the vibration of a structure, the device comprising a stationary casing (C) mounted on the structure and with first and second sets (E 1 , E 2 ) each comprising two contra-rotary rotors ( 11 & 21 and 31 & 41 ) with eccentric flyweights ( 12 & 22 and 32 & 42 ), said flyweights ( 12 , 22 , 32 , 42 ) and said rotors ( 11 , 21 , 31 , 41 ) being disposed respectively in first and second mutually parallel planes ( 100 , 200 ), the centers of rotation of said contra-rotary rotors ( 11 , 21 , 31 , 41 ) representing the corners of a rectangular parallelogram ( 300 ) in said second plane ( 200 ), and the axes of rotation (AX 1 , AX 2 , AX 3 , AX 4 ) of said contra-rotary rotors ( 11 , 21 , 31 , 41 ) being mutually parallel and orthogonal to said first plane ( 100 ),

the device including a stationary main motor (M 1 ) secured to said casing (C), with a through shaft (AM) having a first end (EX 1 ) driving said contra-rotary rotors ( 11 , 21 ) of said first set (E 1 ) and a second end (EX 2 ) driving said contra-rotary rotors ( 31 , 41 ) of said second set (E 2 ).

2. A device according to claim 1 , wherein the two rotors ( 11 & 21 and 31 & 41 ) of each set (E 1 , E 2 ) are disposed symmetrically about a longitudinal axis of symmetry (AL), and said main motor (M 1 ) is arranged inside said rectangular parallelogram ( 300 ) along said axis of symmetry (AL).

3. A device according to claim 1 , including a first orthogonal gear ( 30 ) driving said contra-rotary rotors ( 11 , 21 ) with eccentric flyweights ( 12 , 22 ) of said first set (E 1 ) when it is set into motion by said main motor (M 1 ), the axis of rotation of said first orthogonal gear being disposed in said second plane ( 200 ) and being orthogonal to said axes of rotation (AX 1 , AX 2 ) of said contra-rotary rotors ( 11 , 21 ) of said first set (E 1 ).

4. A device according to claim 3 , wherein said first end (EX 1 ) of said through shaft (AM) carries a first sun gear (P 1 ) for setting into motion a first outer ring gear (CE 1 ) constrained to rotate with said first orthogonal gear ( 30 ).

5. A device according to claim 4 , including speed-reducing gearing for reducing the speed of rotation of said rotors ( 11 , 21 ) having eccentric flyweights ( 12 , 22 ) of said first set (E 1 ).

6. A device according to claim 5 , wherein said speed-reducing gearing includes at least a first planet gear (S 1 ) mounted on a stationary first planet carrier (PS 1 ) disposed between the first sun gear (P 1 ) and the first outer ring gear (CE 1 ).

7. A device according to claim 1 , including a second orthogonal gear ( 30 ) driving said contra-rotary rotors ( 31 , 41 ) with eccentric flyweights ( 32 , 42 ) of said second set (E 2 ) when it is set into motion by said main motor (M 1 ), the axis of rotation of said second orthogonal gear ( 30 ) being disposed in said second plane ( 200 ) and being orthogonal to said axes of rotation (AX 3 , AX 4 ) of said contra-rotary rotors ( 31 , 41 ) of said second set (E 2 ).

8. A device according to claim 7 , wherein said second end (EX 2 ) of said through shaft (AM) carries a second sun gear (P 2 ) for setting into motion a second outer ring gear (CE 2 ) constrained to rotate with said orthogonal gear ( 30 ).

9. A device according to claim 8 , including phase-shifter means for slowing down or accelerating, at least temporarily, the speed of rotation of said rotors ( 31 , 41 ) with eccentric flyweights ( 32 , 42 ) of said second set (E 2 ) in such a manner as to vary their angular phase difference relative to said rotors ( 11 , 21 ) with eccentric flyweights ( 12 , 22 ) of said first set (E 1 ).

10. A device according to claim 9 , wherein said phase-shifter means comprise at least one second planet gear (S 2 ) arranged on a second planet carrier (PS 2 ) that is movable in rotation relative to said second end (EX 2 ), being disposed between the second sun gear (P 2 ) and the second outer ring gear (CE 2 ).

11. A device according to claim 10 , wherein said second planet carrier (PS 2 ) is set into motion by a secondary motor (M 2 ).

12. A device according to claim 11 , wherein said main and secondary motors (M 1 , M 2 ) are concentric.

13. A device according to claim 11 , wherein the two rotors ( 11 & 21 and 31 & 41 ) of each set (E 1 and E 2 ) are disposed symmetrically about a longitudinal axis of symmetry (AL), and said main and secondary motors (M 1 , M 2 ) are arranged in succession along said longitudinal axis of symmetry (AL).

14. A device according to claim 1 , including a computer for varying the angular phase difference between said rotors ( 31 , 41 ) with eccentric flyweights ( 32 , 42 ) of said second set (E 2 ) relative to said rotors ( 11 , 21 ) with eccentric flyweights ( 12 , 22 ) of said first set (E 1 ) as a function of signals coming from a plurality of sensors.

15. A device according to claim 1 , wherein each set (E 1 , E 2 ) comprises one rotor having a thick eccentric flyweight provided with two identical disk portions ( 121 , 122 ) separated by a groove (G), the other rotor then having a thin eccentric flyweight provided with a single disk portion ( 221 ) of thickness lying slightly smaller than the width of said groove (G), the thick and thin flyweights being identical in weight.