IP Library › Granted Patent US 12687180
Granted Patent B2
US 12687180 · App. 19/187,033 · Granted Jul 21, 2026

Hydraulic actuator

Inventors: David Williams (Bristol, GB); Sean Kerr (Bristol, GB)
Assignee: Airbus Operations Limited
F15B11/024B64C25/22F15B2211/62
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Quick Facts
Patent No.
US 12687180
App. No.
19/187,033
Granted
Jul 21, 2026
Kind
B2
Abstract

A hydraulic actuator for a hydraulic actuation system of an aircraft includes a housing defining a cavity, a piston dividing the cavity into extension and retraction chambers and movable relative to the housing to increase volume of one chamber and decrease volume of another of the chambers. A bypass includes first and second bypass ports and a connecting bypass line, and first and second chamber ports opening into the extension and retraction chambers at all positions of the piston relative to the housing for passage of hydraulic fluid. The first and second bypass ports open into one of the extension chamber and retraction chamber when the piston is at a first position relative to the housing so the first bypass port and the second bypass port open into respective ones of the extension chamber and the retraction chamber when the piston is at a second position relative to the housing.

Claims (69)

1 . A hydraulic actuator for a hydraulic actuation system of an aircraft, the hydraulic actuator comprising:

a housing defining a cavity configured to accommodate hydraulic fluid;

a piston within the cavity, such that the piston divides the cavity into an extension chamber and a retraction chamber, wherein the piston and that is movable relative to the housing such that, when the piston moves in a first direction, a volume of the extension chamber increases and a volume of the retraction chamber decreases and, when the piston moved in a second direction that is opposite the first direction, the volume of the extension chamber decreases and the volume of the retraction chamber increases;

a bypass comprising a first bypass port that opens into the cavity, a second bypass port that opens into the cavity, and a bypass line that fluidly connects the first bypass port to the second bypass port;

a first chamber port that is discrete from the first bypass port and from the second bypass port, wherein the first chamber port opens into the extension chamber at all positions of the piston within the cavity of the housing for passage of the hydraulic fluid between an exterior of the hydraulic actuator and the extension chamber; and

a second chamber port that is discrete from the first bypass port and the second bypass port, wherein the second chamber port opens into the retraction chamber at all positions of the piston within the cavity of the housing for the passage of the hydraulic fluid between the exterior of the hydraulic actuator and the retraction chamber;

wherein, when the piston is at a first position within the cavity, the first bypass port and the second bypass port both open into the retraction chamber; and

wherein, when the piston is at a second position within the cavity, the first bypass port opens into the extension chamber and the second bypass port opens into the retraction chamber.

2 . The hydraulic actuator of claim 1 , wherein:

the first chamber port is larger than either of the first bypass port and the second bypass port; and/or

the second chamber port is larger than either of the first bypass port and the second bypass port.

3 . The hydraulic actuator of claim 1 , wherein the bypass comprises a one-way valve that is configured to:

permit fluid flow through the bypass line from the first bypass port to the second bypass port; and

restrict fluid flow through the bypass line from the second bypass port to the first bypass port.

4 . The hydraulic actuator of claim 3 , wherein:

the piston is closer to an end of the cavity when the piston is at the second position than when the piston is at the first position;

the second bypass port is closer than the first bypass port to the end of the cavity; and

the end of the cavity defines, at least in part, an end of the retraction chamber.

5 . The hydraulic actuator of claim 1 , wherein at least a portion of the bypass line has an open cross-sectional area of between 0.5 mm 2 and 14 mm 2 .

6 . The hydraulic actuator of claim 5 , wherein the portion of the bypass line comprises a flow restrictor that is configured to restrict a rate of fluid flow through the bypass line.

7 . The hydraulic actuator of claim 1 , wherein the second position of the piston is at a second end of a range of motion of the piston relative to the housing.

8 . The hydraulic actuator of claim 7 , wherein:

the first position of the piston is at a first end of the range of motion of the piston; and

the first end of the range of motion of the piston is opposite to the second end of the range of motion of the piston.

9 . The hydraulic actuator of claim 1 , wherein the hydraulic actuator is configured so that:

the piston is at the first position when the hydraulic actuator is fully contracted; and

the piston is at the second position when the hydraulic actuator is fully extended.

10 . The hydraulic actuator of claim 1 , wherein only the first chamber port, the second chamber port, the first bypass port, and the second bypass port open into the cavity.

11 . The hydraulic actuator of claim 1 , wherein the bypass line is fluidly connected to the cavity by only the first bypass port and the second bypass port.

12 . The hydraulic actuator of claim 1 , wherein the bypass line is free from any junction with any other flow path.

13 . A hydraulic actuation system for an aircraft, the hydraulic actuation system comprising:

the hydraulic actuator of claim 1 ;

a first hydraulic line fluidly connected to the first chamber port and configured to carry the hydraulic fluid to or from the extension chamber; and

a second hydraulic line fluidly connected to the second chamber port and configured to carry the hydraulic fluid to or from the retraction chamber.

14 . The hydraulic actuation system of claim 13 , wherein the hydraulic actuation system is a landing gear system.

15 . An aircraft comprising the hydraulic actuation system of claim 13 .

16 . A hydraulic actuator for a hydraulic actuation system of an aircraft, the hydraulic actuator comprising:

a housing defining a cavity configured to accommodate hydraulic fluid;

a piston within the cavity, such that the piston divides the cavity into an extension chamber and a retraction chamber, wherein the piston is movable relative to the housing such that, when the piston moves in a first direction, a volume of the extension chamber increases and a volume of the retraction chamber decreases and, when the piston moved in a second direction that is opposite the first direction, the volume of the extension chamber decreases and the volume of the retraction chamber increases;

a bypass comprising a first bypass port that opens into the cavity, a second bypass port that opens into the cavity, and a bypass line that fluidly connects the first bypass port to the second bypass port;

a first chamber port that is discrete from the first bypass port and from the second bypass port, wherein the first chamber port opens into the extension chamber at all positions of the piston within the cavity of the housing for passage of the hydraulic fluid between an exterior of the hydraulic actuator and the extension chamber; and

a second chamber port that is discrete from the first bypass port and the second bypass port, wherein the second chamber port opens into the retraction chamber at all positions of the piston within the cavity of the housing for the passage of the hydraulic fluid between the exterior of the hydraulic actuator and the retraction chamber;

wherein, when the piston is at a first position within the cavity, the first bypass port and the second bypass port both open into:

the extension chamber; or

the retraction chamber;

wherein, when the piston is at a second position within the cavity, the first bypass port opens into the extension chamber and the second bypass port opens into the retraction chamber; and

wherein:

the first chamber port is larger than either of the first bypass port and the second bypass port; and/or

the second chamber port is larger than either of the first bypass port and the second bypass port.

17 . A hydraulic actuation system for an aircraft, the hydraulic actuation system comprising:

the hydraulic actuator of claim 16 ;

a first hydraulic line fluidly connected to the first chamber port and configured to carry the hydraulic fluid to or from the extension chamber; and

a second hydraulic line fluidly connected to the second chamber port and configured to carry the hydraulic fluid to or from the retraction chamber.

18 . A hydraulic actuator for a hydraulic actuation system of an aircraft, the hydraulic actuator comprising:

a housing defining a cavity configured to accommodate hydraulic fluid;

a piston within the cavity, such that the piston divides the cavity into an extension chamber and a retraction chamber, wherein the piston is movable relative to the housing such that, when the piston moves in a first direction, a volume of the extension chamber increases and a volume of the retraction chamber decreases and, when the piston moved in a second direction that is opposite the first direction, the volume of the extension chamber decreases and the volume of the retraction chamber increases;

a bypass comprising a first bypass port that opens into the cavity, a second bypass port that opens into the cavity, and a bypass line that fluidly connects the first bypass port to the second bypass port;

a first chamber port that is discrete from the first bypass port and from the second bypass port, wherein the first chamber port opens into the extension chamber at all positions of the piston within the cavity of the housing for passage of the hydraulic fluid between an exterior of the hydraulic actuator and the extension chamber; and

a second chamber port that is discrete from the first bypass port and the second bypass port, wherein the second chamber port opens into the retraction chamber at all positions of the piston within the cavity of the housing for the passage of the hydraulic fluid between the exterior of the hydraulic actuator and the retraction chamber;

wherein, when the piston is at a first position within the cavity, the first bypass port and the second bypass port both open into:

the extension chamber; or

the retraction chamber;

wherein, when the piston is at a second position within the cavity, the first bypass port opens into the extension chamber and the second bypass port opens into the retraction chamber; and

wherein at least a portion of the bypass line has an open cross-sectional area of between 0.5 mm 2 and 14 mm 2 .

19 . The hydraulic actuator of claim 18 , wherein the portion of the bypass line comprises a flow restrictor that is configured to restrict a rate of fluid flow through the bypass line.

20 . A hydraulic actuation system for an aircraft, the hydraulic actuation system comprising:

the hydraulic actuator of claim 18 ;

a first hydraulic line fluidly connected to the first chamber port and configured to carry the hydraulic fluid to or from the extension chamber; and

a second hydraulic line fluidly connected to the second chamber port and configured to carry the hydraulic fluid to or from the retraction chamber.