Center biased actuator

Patent metadata

Field	Value
Publication number	US-11027830-B2
Application number	US-201816189073-A
Country	US
Kind code	B2
Filing date	Nov 13, 2018
Priority date	Nov 16, 2017
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

First claim

The invention claimed is:

1. A center biased actuator comprising:
an outer cylinder;
a slave cylinder arranged to be linearly transposed within the outer cylinder;
a rod assembly having a piston arranged to be linearly transposed within the slave cylinder and a rod extending from the outer cylinder;
one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder;
one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder;
wherein the one or more second dynamic seals are arranged to inhibit hydraulic fluid leaking from the outer cylinder by passing the one or more second dynamic seals and entering a chamber that is vented to atmosphere via a gas vent; and
a gas chamber comprising a sealed expandable chamber containing gas, the expandable chamber being arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

2. The center biased actuator according to claim 1 , wherein the expandable chamber comprises a metal bellows.

3. The center biased actuator according to claim 1 , wherein the expandable chamber is mounted within an accumulator cylinder that is coupled to a hydraulic fluid port through the outer cylinder.

4. The center biased actuator according to claim 1 , wherein the rod assembly includes a blind hole which opens into and is in fluid communication with an internal chamber of the slave cylinder and wherein the expandable chamber is mounted within the blind hole.

5. The center biased actuator according to claim 1 , comprising end stops arranged to define first and second movement extremities of the slave cylinder.

6. The center biased actuator according to claim 1 , wherein the outer cylinder has a length extending from a first end to a second end with a midpoint equidistant between the first end and the second end, and the one or more second dynamic seals are located closer to the midpoint than to either the first end or the second end.

7. The center biased actuator according to claim 1 , wherein the sealed expandable chamber is defined by a chamber wall that is unitary in nature.

8. The center biased actuator according to claim 1 , wherein the sealed expandable chamber is defined by a chamber wall arranged, in use, to deform as the expandable chamber expands and contracts.

9. The center biased actuator according to claim 1 , wherein the center biased actuator is arranged to be constantly operationally biased to assume the intermediate condition by the sealed expandable chamber.

10. The center biased actuator according to claim 1 , wherein the outer cylinder comprises a first axial face and a second axial face connected by one or more first sidewalls to define a primary chamber, the first axial face having a first through-hole.

11. The center biased actuator according to claim 10 , wherein the slave cylinder is arranged to be linearly transposed within the primary chamber, the slave cylinder comprising a third axial face and a fourth axial face connected by one or more second sidewalls to define a slave cylinder chamber, the third axial face having a second through-hole, the slave cylinder being constrained to move only between first and second extremities within the primary chamber so as to leave at least one free portion of the primary chamber, the outer cylinder including a venting port in fluid communication with the free portion of the primary chamber.

12. The center biased actuator according to claim 11 , wherein the piston is arranged to be linearly transposed within the slave cylinder chamber and the rod is extendable though the second and first through-holes so as to project a free end of the rod from the outer cylinder.

13. The center biased actuator according to claim 12 , wherein the one or more first dynamic seals are mounted at or adjacent to the first through hole and arranged to act on an external surface of the rod to inhibit working fluid within the chamber passing through the first through-hole.

14. The center biased actuator according to claim 12 , wherein the one or more second dynamic seals are mounted on the one or more first sidewalls of the outer cylinder and are arranged to act on an external surface of the one or more second sidewalls of the slave cylinder to inhibit working fluid within the chamber passing to the free portion of the primary chamber.

15. An assembly including a center biased actuator according to claim 1 arranged to bias a first part of the assembly to assume a predetermined position relative to a second part, the assembly being arranged, in use, to force the actuator to assume the first condition when in a first state and having a second state in which the actuator moves the first part of the assembly to assume the predetermined position relative to the second part.

16. The assembly according to claim 15 comprising an aircraft assembly.

17. The assembly according to claim 16 comprising an aircraft landing gear assembly.

18. The assembly according to claim 17 , wherein the first part comprises a bogie beam and the second part comprises a main strut.

19. An aircraft landing gear assembly including a center biased actuator arranged to bias a first part of the assembly to assume a predetermined position relative to a second part, the assembly being arranged, in use, to force the actuator to assume the first condition when in a first state and having a second state in which the actuator moves the first part of the assembly to assume the predetermined position relative to the second part, wherein the first part comprises a bogie beam and the second part comprises a main strut, the center biased actuator comprising:
an outer cylinder;
a slave cylinder arranged to be linearly transposed within the outer cylinder;
a rod assembly having a piston arranged to be linearly transposed within the slave cylinder and a rod extending from the outer cylinder;
one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder;
one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder;
wherein the one or more second dynamic seals are arranged to inhibit hydraulic fluid leaking from the outer cylinder by passing the one or more second dynamic seals and entering a chamber that is vented to atmosphere via a gas vent; and
a gas chamber comprising a sealed expandable chamber containing gas, the expandable chamber being arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition, wherein the expandable chamber comprises metal bellows.

Assignees

• Safran Landing Systems Uk Ltd

Inventors

• Sharpe Peter

Classifications

• B64C25/60 Primary

  Oleo legs · CPC title

• F16F9/526

  Self-adjustment of fluid springs · CPC title

• F16F9/063

  comprising a hollow piston rod · CPC title

• B64C25/34

  wheeled type, e.g. multi-wheeled bogies · CPC title

• F16F9/088

  comprising a gas spring with a flexible wall provided within the cylinder on the piston rod of a monotubular damper or within the inner tube of a bitubular damper · CPC title