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1. WO2004063595 - MECANISME D'ENGRENAGE A VERROUILLAGE ET DEVERROUILLAGE AUTOMATIQUES UNIVERSEL

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

What is claimed is:
1. A self-locking device for a gear set, configured for being forward-driven at an input in either of first and second rotational directions, and for substantially preventing an output from being back-driven in either of the rotational directions, the device comprising:
an input including a drive shaft configured for being forward-driven in either of the first and second rotational directions;
an output including a gear disposed to rotate with the drive shaft;
first and second releasable couplings coupled to the gear;
first and second ratchets respectively coupled to the first and second releasable couplings;
the first ratchet disposed to substantially prevent rotation in the first direction and to permit rotation in the second direction;
the second ratchet disposed to substantially prevent rotation in the second direction and permit rotation in the first direction;
the first releasable coupling disposed to selectively couple and decouple the gear with the first ratchet;
the second releasable coupling disposed to selectively couple and decouple the gear with the second ratchet; and
the releasable couplings being configured to automatically, selectively engage and disengage the ratchets with the gear, said selective engaging and disengaging permitting the input to be said forward-driven in either of the rotational directions and substantially preventing the output from being said back-driven in either of the rotational directions.

2. The self-locking device of claim 1, wherein:
the application of a torque to forward-drive the input in the first direction substantially couples and decouples respectively the second and first ratchets with the gear, permitting the gear to be forward-driven substantially freely in the first direction; and
the application of a torque to forward-drive the input in the second direction substantially couples and decouples respectively the first and second ratchets with the gear, peπnitting the gear to be forward-driven substantially freely in the second direction.

3. The self-locking device of claim 1 , wherein:
the application of a torque disposed to back-drive the output in the first direction substantially couples the first ratchet with the gear, the first ratchet substantially preventing the gear from being said back-driven in the first direction; and
the application of a torque disposed to back-drive the output in the second direction substantially couples the second ratchet with the gear, the second ratchet substantially preventing the gear from being said back-driven in the second direction.

4. The self-locking device of claim 1, wherein at least one of the releasable couplings comprises a f iction coupling.

5. The self-locking device of claim 4, wherein the at least one releasable coupling comprises a friction plate coupling.

6. The self-locking device of claim 4, wherein the at least one releasable coupling comprises a multiple plate coupling.

7. The self-locking device of claim 4, wherein the at least one releasable coupling comprises a conical friction coupling.

8. The self-locking device of claim 1, wherein at least one of the releasable couplings comprises a mechanical coupling.

9. The self-locking device of claim 1, wherein the gear, the first and second releasable couplings, and the first and second ratchets are disposed substantially coaxially with the drive shaft.

10. The self-locking device of claim 1, wherein the first and second ratchets are disposed on opposing sides of the gear.

11. The self-locking device of claim 10, wherein the first releasable coupling is interposed between the gear and the first ratchet and the second releasable coupling is interposed between the gear and the second ratchet.

12. The self-locking device of claim 1, wherein the gear comprises an internal helical gear.

13. The self-locking device of claim 12, wherein one end of the drive shaft is mounted to the internal helical gear.

14. The self-locking device of claim 13, further comprising an output shaft disposed coaxially with the drive shaft, the output shaft having a helical thread disposed on one end thereof, the helical thread being threadably engaged with the internal helical gear.

15. The self-locking device of claim 14, wherein:
the application of a torque disposed to said forward-drive the drive shaft in the first direction substantially loosens the internal helical gear on the helical thread, to substantially couple and decouple respectively the second and first ratchets with the internal helical gear, permitting the internal helical gear to be forward-driven substantially freely in the first direction; and
the application of a torque disposed to forward-drive the drive shaft in the second direction substantially tightens the internal helical gear on the helical thread, to substantially couple and decouple respectively the first and second ratchets with the internal helical gear, permitting the internal helical gear to be said forward-driven substantially freely in the second first direction.

16. The self-locking device of claim 14, wherein:
the application of a torque disposed to said back-drive the internal helical gear in the first direction substantially tightens the internal helical gear on the helical tliread, to substantially couple the first ratchet with the internal helical gear, the first ratchet substantially preventing the internal helical gear from being back-driven in the first direction; and
the application of a torque disposed to back-drive the internal helical gear in the second direction substantially loosens the internal helical gear on the helical thread, to substantially couple the second ratchet with the internal helical gear, the second ratchet substantially preventing the internal helical gear from being said back-driven in the second direction.

17. The self-locking device of claim 1, wherein the gear is configured for axial movement respectively away from and towards the first and second releasable couplings while being said forward-driven in the first and second directions.

18. The self-locking device of claim 1 , wherein the gear is configured for axial movement respectively towards and away from the first and second releasable couplings while being said back-driven in the first and second directions.

19. The self-locking device of claim 1, wherein the gear comprises an external gear, the external gear being disposed to mesh with the gear set.

20. The self-locking device of claim 19, wherein the external gear comprises a worm gear.

21. The self-locking device of claim 19, wherein the external gear comprises a helical gear.

22. The self-locking device of claim 19, wherein said selective coupling and decoupling of the external gear with the first and second ratchets is effected by natural axial forces on the external gear, the natural axial forces being generated by engagement of the external gear with the gear set.

23. The self-locking device of claim 19, wherein: the application of a torque disposed to forward-drive the drive shaft in the first direction effects an axial force on the external gear, the axial force urging the external gear towards the second ratchet to substantially couple and decouple respectively the second and first ratchets with the external gear, permitting the gear to be forward-driven substantially freely in the first direction; and
the application of a torque disposed to forward-drive the drive shaft in the second direction effects an axial force on the external gear, the axial force urging the external gear towards the first ratchet to substantially couple and decouple respectively the first and second ratchets with the external gear, permitting the gear to be forward-driven substantially freely in the second direction.

24. The self-locking device of claim 19, wherein:
the application of a torque disposed to back-drive the gear in the first direction effects an axial force on the external gear, the axial force urging the external gear towards the first ratchet to substantially couple the first ratchet with the external gear, the first ratchet substantially preventing the gear from being back-driven in the first direction; and
the application of a torque disposed to back-drive the gear in the second direction effects an axial force on the external gear, the axial force urging the external gear towards the second ratchet to substantially couple the second ratchet with the external gear, the second ratchet substantially preventing the gear from being back-driven in the second direction.

25. The self-locking device of claim 1, wherein the first and second ratchets respectively comprise first and second ratchet cams disposed to engage respective first and second pawls.

26. The self-locking device of claim 25, wherein the first and second pawls are spring loaded.

27. The self-locking device of claim 25, wherein the first and second pawls are coupled to a housing, the gear, the first and second ratchets, and the first and second releasable couplings being disposed in the housing.

28. The self-locking device of claim 25, further comprising first and second bearing members, the first bearing member being interposed between the first ratchet and the housing and the second bearing member being interposed between the second ratchet and the housing.

29. A gearbox comprising:
the self-locking device of claim 1,
a gear set coupled to the self-locking device, the gear set including at least one gear member.

30. A self-locking device for a»gear set, the device comprising:
a drive shaft;
a gear disposed to rotate with the drive shaft;
first and second releasable couplings disposed on opposing sides of the gear;
first and second ratchets respectively coupled to the first and second releasable couplings, the first releasable coupling interposed between the gear and the first ratchet and the second releasable coupling interposed between the gear and the second ratchet; the first ratchet disposed to substantially prevent rotation in a first direction and to permit rotation in a second direction;
the second ratchet disposed to substantially prevent rotation in the second direction and permit rotation in the first direction;
the first releasable coupling disposed to selectively couple and decouple the gear with the first ratchet; and
the second releasable coupling disposed to selectively couple and decouple the gear with the second ratchet.

31. A gearbox comprising:
a gear set including a gear meshed with a wheel;

the gear being disposed to rotate with a drive shaft;
first and second releasable couplings coupled to the gear;
first and second ratchets respectively coupled to the first and second releasable couplings;
the first ratchet disposed to substantially prevent rotation in a first direction and to permit rotation in a second direction;
the second ratchet disposed to substantially prevent rotation in the second direction and permit rotation in the first direction;
the first releasable coupling disposed to selectively couple and decouple the gear with the first ratchet;
the second releasable coupling disposed to selectively couple and decouple the gear with the second ratchet; and
the releasable couplings being configured to automatically, selectively engage and disengage the ratchets with the gear, the selective engaging and disengaging permitting the input to be forward-driven in either of the rotational directions and substantially preventng the output from being back-driven in either of the rotational directions.

32. The gearbox of claim 31 , wherein:
the gear comprises a worm gear; and
the wheel comprises a worm wheel.

33. The gearbox of claim 31 , wherein:
the gear comprises a helical gear; and
the wheel comprises a helical wheel.

34. The gearbox of claim 33, wherein an axis of rotation of the helical gear is substantially perpendicular to an axis of rotation of the helical wheel.

35. The gearbox of claim 33, wherein an axis of rotation of the helical gear is substantially parallel to an axis of rotaton of the helical wheel.

36. The gearbox of claim 31 , wherein at least one, of the releasable couplings comprises a friction coupling.

37. The gearbox of claim 36, wherein the at least one releasable coupling comprises a friction plate.

38. The gearbox of claim 31 , wherein at least one of the releasable couplings comprises a mechanical coupling.

39. The gearbox of claim 31 , wherein said selective coupling and decoupling of the gear with the first and second ratchets is effected by natural axial forces in the gear, the natural axial forces being generated by engagement of the gear with the wheel.

40. The gearbox of claim 31 , wherein:
the application of a torque disposed to forward-drive the drive shaft in the first direction effects an axial force on the gear, the axial force urging the gear towards the second ratchet to substantially couple and decouple respectively the second and first ratchets with the gear, permitting the wheel to be forward-driven substantially freely in the first direction; and
. the application of a torque disposed to forward-drive the drive shaft in the second direction effects an axial force on the gear, the axial force urging the gear towards the first ratchet to substantially couple and decouple the first and second ratchets with the gear, permitting the wheel to be forward-driven substantially freely in the second direction; and

41. The gearbox of claim 31 , wherein:
the application of a torque disposed to back-drive the wheel in the first direction effects an axial force on the gear, the axial force urging the gear towards the first ratchet to substantially couple the first ratchet with the gear, the first ratchet substantially preventing the wheel from being back-driven in the first direction; and
the application of a torque disposed to back-drive the wheel in the second direction effects an axial force on the gear, the axial force urging the gear towards the second ratchet to substantially couple the second ratchet with the gear, the second ratchet substantially preventing the wheel from being back-driven in the second direction.

42. A method of fabricating a gearbox, the method comprising:
providing a gear set including a gear meshed with a wheel, the gear being disposed to rotate with a drive shaft;
coupling first and second releasable couplings to the gear;
coupling first and second ratchets respectively to the first and second releasable couplings;
disposing the first ratchet to substantially prevent rotation in the first direction and to permit rotation in the second direction;
disposing the second ratchet to substantially prevent rotation in the second direction and permit rotation in the first direction;
disposing the first releasable coupling to selectively couple and decouple the gear with the first ratchet;
disposing the second releasable coupling to selectively couple and decouple the gear with the second ratchet; and
the releasable couplings being configured to automatically, selectively engage and disengage the ratchets with the gear, said selective engaging and disengaging permitting the input to be forward-driven in either of the rotational directions and substantially preventing the output from being back-driven in either of the rotational directions.