Lead-lag damper

1. A lead-lag damper comprising:

an outer tube mechanically coupled to a first coupler;

one or more substantially annular elastomer bearings inside the outer tube;

a spacer tube concentrically and movably positioned inside the outer tube and partially surrounded by the one or more elastomeric bearings;

an inner tube mechanically coupled to a second coupler and concentrically positioned inside the spacer tube, wherein sidewalls of the inner tube define a first fluid chamber inside the inner tube; and

a floating annular ring positioned in concentric alignment about a portion of the outer tube, wherein

the one or more elastomer bearings and the floating annular ring define at least a second fluid chamber and a third fluid chamber inside the outer tube,

the second and third fluid chambers are configured in fluidic communication with one another and with the first fluid chamber,

the floating annular ring includes an inside surface with two or more protrusions,

the two or more protrusions each extend at least partially across a width of the inside surface of the floating annular ring and are configured to occasionally reposition the floating annular ring to maintain a coaxial relationship to the spacer tube, and

the floating annular ring is configured to:

substantially surround the spacer tube,

track radially with a spacer tube misalignment, and

control the fluidic communication between the second fluid chamber and the third fluid chamber.

2. The lead-lag damper of claim 1 , wherein the floating annular ring is made from one or more of a polymeric material, rubber, vulcanized rubber, a ceramic material, a metal, or a metal alloy.

3. The lead-lag damper of claim 1 , further comprising:

a guide structure inside the outer tube, the guide structure configured to limit movement of the floating annular ring to a predefined axial position and allow the floating annular ring to translate radially along with the spacer tube in operation.

4. The lead-lag damper of claim 3 , wherein the guide structure is configured to allow the floating annular ring to move radially within a limited range effective to control a consistent fluid exchange gap between the second fluid chamber and the third fluid chamber of the outer tube.

5. The lead-lag damper of claim 3 , wherein the guide structure is configured to move within a limited range inside the outer tube or is mechanically coupled to one of the spacer tube and the outer tube.

6. The lead-lag damper of claim 1 , further comprising:

a plunger-spring system inside the inner tube to provide volume compensation fluid exchange between one or both of the second and third fluid chambers and the first fluid chamber.

7. The lead-lag damper of claim 1 , further comprising:

one or more seeping holes in a sidewall of the inner tube, the seeping holes configured to provide fluidic communication between the first fluid chamber and one or both of the second and third fluid chambers without causing a dynamic pressure change in the first fluid chamber.

8. A lead-lag damper comprising:

an outer tube mechanically coupled to a first coupler;

one or more substantially annular elastomer bearings inside the outer tube;

a spacer tube concentrically and movably positioned inside the outer tube and partially surrounded by the one or more elastomeric bearings;

an inner tube mechanically coupled to a second coupler and concentrically positioned inside the spacer tube, wherein sidewalls of the inner tube define a first fluid chamber inside the inner tube;

a first floating annular ring positioned in concentric alignment about a first portion of the outer tube; and

a second floating annular ring positioned in concentric alignment about a second portion of the outer tube offset from the first portion, wherein

the one or more elastomer bearings, the first floating annular ring, and the second floating annular ring at least partially define one or more of a second fluid chamber, a third fluid chamber, and a fourth fluid chamber inside the outer tube,

the second, third, and fourth fluid chambers are configured in fluidic communication with one another and with the first fluid chamber, and

the first floating annular ring and the second floating annular ring are configured to:

substantially surround the spacer tube, and

control a consistent fluid exchange gap, respectively, between the second and third fluid chambers and the third and fourth fluid chambers of the outer tube.

9. The lead-lag damper of claim 8 , wherein

at least one of the first floating annular ring and the second floating annular ring includes an inside surface with two or more protrusions,

the two or more protrusions each extend at least partially across a width of the inside surface,

the two or more protrusions are substantially equidistantly distributed along the inside surface, and

the two or more protrusions are configured to occasionally reposition the first floating annular ring or the second floating annular ring to maintain a coaxial relationship to the spacer tube.

10. The lead-lag damper of claim 8 , wherein the first floating annular ring and the second floating annular ring are made from a material that is dissimilar to a material of the spacer tube to prevent galvanic corrosion or galling in operation.

11. The lead-lag damper of claim 8 , further comprising:

a first guide structure and a second guide structure inside the outer tube, the first guide structure and the second guide structure configured to limit movement of the first floating annular ring and the second floating annular ring, respectively, to a predefined axial position and allow the first floating annular ring and the second floating annular ring to move or rotate radially along with the spacer tube in operation.

12. The lead-lag damper of claim 8 , further comprising:

a plunger-spring system inside the inner tube to provide volume compensation fluid exchange between the first fluid chamber and one or more of the second, third, and fourth fluid chambers.

13. A lead-lag damper comprising:

an outer tube mechanically coupled to a first coupler;

one or more substantially annular elastomer bearings inside the outer tube;

a spacer tube concentrically and movably positioned inside the outer tube and partially surrounded by the one or more elastomeric bearings;

an inner tube mechanically coupled to a second coupler and concentrically positioned inside the spacer tube, wherein sidewalls of the inner tube define a first fluid chamber inside the inner tube;

a first floating annular ring positioned in concentric alignment about a first location inside the outer tube, wherein the first floating annular ring is configured to substantially surround the spacer tube;

a first guide structure about the first location inside the outer tube, the first guide structure configured to limit movement of the first floating annular ring to a predefined axial position and allow the first floating annular ring to move and rotate radially along with the spacer tube;

a second floating annular ring positioned in concentric alignment about a second location inside the outer tube offset from the first location; and

a second guide structure about the second location inside the outer tube, the second guide structure configured to substantially surround the spacer tube, limit movement of the second floating annular ring to a predefined axial position, and allow the second floating annular ring to move and rotate radially.

14. The lead-lag damper of claim 13 , wherein

the one or more elastomer bearings, the first guide structure, and the first floating annular ring define at least partially a second fluid chamber and a third fluid chamber, and

the first floating annular ring is configured to control a consistent fluid exchange between the second and third fluid chambers through a fluid exchange gap between an inside surface of the first annular ring and an outside surface of the spacer tube.

15. The lead-lag damper of claim 14 , further comprising:

a raised or recessed annular tab on an outside surface of the spacer tube, the raised or recessed annular tab configured to:

enter a fluid exchange gap defined by the first floating annular ring in a tension state or a compression state; and

further control the fluid exchange between the second fluid chamber and the third fluid chamber through the fluid exchange gap.

16. The lead-lag damper of claim 13 , wherein

the one or more elastomer bearings, the second guide structure, and the second floating annular ring define at least partially the third fluid chamber and a fourth fluid chamber, and

the second floating annular ring is configured to control a consistent fluid exchange between the third and fourth fluid chambers through a fluid exchange gap between an outside surface of the second annular ring and an inside surface of the outer tube.

17. A method to manufacture a lead-lag damper, the method comprising:

mechanically coupling an outer tube to a first coupler;

fitting one or more substantially annular elastomer bearings inside the outer tube;

fitting a spacer tube concentrically and movably inside the outer tube, wherein the spacer tube is partially surrounded by the one or more elastomeric bearings;

mechanically coupling an inner tube to a second coupler, wherein sidewalls of the inner tube define a first fluid chamber inside the inner tube;

fitting a plunger-spring system inside the inner tube to provide volume compensation fluid exchange between the first fluid chamber and two or more fluid chambers of the outer tube;

forming one or more seeping holes in the sidewalls of the inner tube and the spacer tube to facilitate fluidic exchange between the first chamber and the two or more fluid chambers of the outer tube;

fitting a floating annular ring in concentric alignment about a portion of the outer tube such that the floating annular ring substantially surrounds the spacer tube and is radially movable to control a consistent fluid exchange between the one or more fluid chambers of the outer tube; and

partially fitting the inner tube inside the spacer tube.

18. The method of claim 17 , further comprising:

forming a guide structure inside the outer tube to limit movement of the floating annular ring to a predefined axial position and to allow the floating annular ring to move radially within a limited range effective to control a consistent fluid exchange gap between the one or more fluid chambers of the outer tube.

19. The method of claim 17 , further comprising:

forming the floating annular ring by disposing two or more protrusions on an inside surface of the floating annular ring such that the two or more protrusions occasionally reposition the annular ring to maintain a coaxial relationship to the spacer tube.