Hydraulic systems for shrinking landing gear

Patent metadata

Field	Value
Publication number	US-10696381-B2
Application number	US-201815866107-A
Country	US
Kind code	B2
Filing date	Jan 9, 2018
Priority date	Jan 9, 2018
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

Hydraulic systems for shrinking landing gear shrink are described. An example apparatus includes a landing gear strut, a transfer cylinder, and aircraft hydraulics. The landing gear strut has an outer cylinder and an inner cylinder. The inner cylinder moves relative to the outer cylinder from a first position to a second position as the landing gear strut moves from a deployed position to a retracted position. The landing gear strut has a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position. The transfer cylinder exchanges hydraulic fluid and gas with the landing gear strut as the landing gear strut moves from the deployed position to the retracted position. The aircraft hydraulics hydraulically actuate the landing gear strut to move from the deployed position to the retracted position.

First claim

What is claimed is:

1. An apparatus comprising:
a landing gear strut having an outer cylinder and an inner cylinder, the inner cylinder to move relative to the outer cylinder from a first position to a second position as the landing gear strut moves from a deployed position to a retracted position, the landing gear strut having a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position;
a transfer cylinder to exchange a first pressurized hydraulic fluid and a pressurized gas with the landing gear strut as the landing gear strut moves from the deployed position to the retracted position;
aircraft hydraulics to hydraulically actuate the landing gear strut to move from the deployed position to the retracted position; and
a pressure-operated check valve operatively coupled to the aircraft hydraulics and operatively positioned between the transfer cylinder and the landing gear strut, the pressure-operated check valve to control the exchange of the pressurized gas between the transfer cylinder and the landing gear strut based on a second pressurized hydraulic fluid received at the pressure-operated check valve from the aircraft hydraulics as the landing gear strut moves from the deployed position to the retracted position, wherein the pressurized gas passes from a strut gas volume of the landing gear strut through the pressure-operated check valve and into a cylinder gas volume of the transfer cylinder in response to the aircraft hydraulics providing the second pressurized hydraulic fluid to the pressure-operated check valve.

2. The apparatus of claim 1 , wherein the pressure-operated check valve is to prevent the pressurized gas contained within the strut gas volume from passing into the cylinder gas volume when the pressure-operated check valve is not receiving the second pressurized hydraulic fluid from the aircraft hydraulics.

3. The apparatus of claim 1 , wherein the landing gear strut includes a strut shrink piston, a strut shrink volume, a strut liquid volume, a first port, and a second port, the strut shrink volume being in fluid communication with the first port, the strut shrink piston being located between the outer cylinder and the inner cylinder within the strut shrink volume, the strut liquid volume being in fluid communication with the strut gas volume, the strut gas volume being in fluid communication with the second port, the first port being in fluid communication with the transfer cylinder, the second port being in fluid communication with the pressure-operated check valve.

4. The apparatus of claim 3 , wherein the strut shrink volume includes the first pressurized hydraulic fluid, the strut liquid volume includes a third pressurized hydraulic fluid isolated from the first pressurized hydraulic fluid, and the strut gas volume includes the pressurized gas.

5. The apparatus of claim 3 , wherein the strut shrink piston is to move the inner cylinder away from the first position and toward the second position in response to an increase in the strut shrink volume, the strut gas volume to decrease in response to the increase in the strut shrink volume.

6. The apparatus of claim 1 , wherein the transfer cylinder includes a barrel and a transfer piston, the transfer piston to move relative to the barrel from an extended position to a compressed position as the landing gear strut moves from the deployed position to the retracted position, the transfer cylinder having a first length when the transfer piston is in the extended position and a second length less than the first length when the transfer piston is in the compressed position.

7. The apparatus of claim 6 , wherein the transfer cylinder further includes a cylinder shrink volume, an atmospheric gas volume, a first port, a second port, and a third port, the cylinder shrink volume being in fluid communication with the first port of the transfer cylinder, the cylinder gas volume being in fluid communication with the second port of the transfer cylinder, the atmospheric gas volume being in fluid communication with the third port of the transfer cylinder, the first port of the transfer cylinder being in fluid communication with the landing gear strut, the second port of the transfer cylinder being in fluid communication with the pressure-operated check valve.

8. The apparatus of claim 7 , wherein the cylinder shrink volume includes the first pressurized hydraulic fluid, the cylinder gas volume includes the pressurized gas, and the atmospheric gas volume includes atmospheric gas, and wherein the first pressurized hydraulic fluid the pressurized gas, and the atmospheric gas are isolated from one another.

9. The apparatus of claim 7 , wherein the transfer piston is to decrease the cylinder shrink volume and increase the cylinder gas volume as the landing gear strut moves from the deployed position to the retracted position.

10. The apparatus of claim 7 , wherein the transfer piston includes a shaft, a first body, and a second body, the shaft being movable relative to the barrel, the first body extending radially from the shaft and being located between the cylinder shrink volume and the atmospheric gas volume, the second body extending radially from the shaft and being located between the cylinder gas volume and the atmospheric gas volume.

11. The apparatus of claim 1 , further comprising a compensator and a compensator check valve, the compensator being in fluid communication with the compensator check valve, the compensator check valve being in fluid communication with a strut shrink volume of the landing gear strut and a cylinder shrink volume of the transfer cylinder, the compensator including a compensator shrink volume and a spring-operated compensator piston, the spring-operated compensator piston to bias a third pressurized hydraulic fluid contained in the compensator shrink volume to flow from the compensator to the compensator check valve, the spring-operated compensator piston including an indicator to indicate a volume of the third pressurized hydraulic fluid remaining in the compensator shrink volume.

12. An apparatus comprising:
a landing gear strut having an outer cylinder and an inner cylinder, the outer cylinder being rotatably coupled to a wing of an aircraft, the inner cylinder to move relative to the outer cylinder from a first position to a second position as the landing gear strut moves from a deployed position to a retracted position, the landing gear strut having a first length when the inner cylinder is in the first position and a second length less than the first length when the inner cylinder is in the second position;
a transfer cylinder to exchange a pressurized hydraulic fluid and a pressurized gas with the landing gear strut as the landing gear strut moves from the deployed position to the retracted position;
aircraft hydraulics to hydraulically actuate the landing gear strut to move from the deployed position to the retracted position; and
a walking beam linkage including a walking beam and a hanger link, the hanger link having a first end and a second end, the first end of the hanger link being rotatably coupled to the aircraft, the walking beam having a first end and a second end, the first end of the walking beam being rotatably coupled to the outer cylinder, the second end of the walking beam being rotatably coupled to the second end of the hanger link, the transfer cylinder having a first end and a second end, the first end of the transfer cylinder being rotatably coupled to the outer cylinder, the second end of the transfer cylinder being rotatably coupled to the second end of the hanger link and to the s

Assignees

• Boeing Co

Inventors

• Plude Leo W
• Bryant Malcolm S
• Lindahl Gary M

Classifications

• B64C25/60

  Oleo legs · CPC title

• B64C25/22 Primary

  fluid · CPC title