Aircraft system, hydraulic actuator for aircraft system and aircraft

Abstract

The invention relates to an aircraft system, a hydraulic actuator for an aircraft system, and an aircraft. An aircraft system includes: a hydraulic actuator; an inlet line for supplying hydraulic fluid to the hydraulic actuator; an outlet line for removing hydraulic fluid from the hydraulic actuator; a first one-way valve configured to allow fluid to flow along the inlet line in a direction toward the hydraulic actuator; and a second one-way valve configured to allow fluid to flow along the outlet line in a direction away from the hydraulic actuator.

Description

Technical Field

[0001] The present invention relates to an aircraft system including a hydraulic actuator, a hydraulic actuator, and an aircraft including such an aircraft system and / or such a hydraulic actuator. Background Technology

[0002] Many aircraft systems use hydraulic actuators to apply force to other components of the aircraft system. For example, some aircraft braking systems use hydraulic actuators to apply braking force to the aircraft's wheels, and some aircraft landing gear extension and retraction systems (LGERS) use hydraulic actuators to extend and retract the aircraft's landing gear. Summary of the Invention

[0003] A first aspect of the invention provides an aircraft system comprising: a hydraulic actuator; an inlet line for supplying hydraulic fluid to the hydraulic actuator; an outlet line for removing hydraulic fluid from the hydraulic actuator; a first check valve configured to allow fluid to flow along the inlet line in a direction toward the hydraulic actuator; and a second check valve configured to allow fluid to flow along the outlet line in a direction away from the hydraulic actuator.

[0004] By providing both inlet and outlet lines, fluid recirculation through the hydraulic actuator can be achieved. For example, fluid can circulate through the chamber of the hydraulic actuator, where both the inlet and outlet lines are in fluid communication with the chamber. This contrasts with known hydraulic actuators in aircraft systems, such as aircraft braking systems, which typically exhibit a dead volume where no renewal of the hydraulic fluid is observed during normal operation. By providing fluid recirculation through the hydraulic actuator, the aging of the hydraulic fluid can be more widely distributed throughout the aircraft hydraulic system, meaning that this aging is more likely to be obtained by sampling the hydraulic fluid within the aircraft hydraulic system. This can lead to a more predictable and / or reliable state of the hydraulic fluid in the aircraft system. Fluid recirculation can also provide improved thermal cycling, such as reducing the temperature of the hydraulic fluid contained within the aircraft system during use.

[0005] Providing a first check valve and a second check valve facilitates fluid recirculation through the hydraulic actuator. For example, when hydraulic fluid is received from a pressure source via the inlet line, the second check valve can prevent the hydraulic fluid from flowing along the outlet line toward the hydraulic actuator. The first check valve can prevent the hydraulic fluid from leaving the hydraulic actuator along the inlet line.

[0006] The aircraft system may include a pressure source for supplying hydraulic fluid to an inlet line. The inlet line may be in fluid communication with the pressure source. The aircraft system may include a reservoir for receiving hydraulic fluid from an outlet line. The outlet line may be in fluid communication with the reservoir.

[0007] A hydraulic actuator may include an inlet port in fluid communication with an inlet line and an outlet port in fluid communication with an outlet line. The inlet port may be located on a first side of the hydraulic actuator, and the outlet port may be located on a second side of the hydraulic actuator, which differs from the first side. This allows for a relatively simple internal path of hydraulic fluid through the hydraulic actuator, such as from one side to the other, compared to a hydraulic actuator where both the inlet and outlet ports are located on the same side.

[0008] The first side of the hydraulic actuator can be configured such that, when the aircraft system is installed inside the aircraft in use and the aircraft is on a horizontal surface, the first side of the hydraulic actuator is located below the second side of the hydraulic actuator. The hydraulic actuator can also be configured such that, when the aircraft system is installed inside the aircraft in use and the aircraft is on a horizontal surface, the inlet port is located at the bottom of the hydraulic actuator, and the outlet port is located at the top of the hydraulic actuator. In this way, any air bubbles contained in the hydraulic fluid within the hydraulic actuator during use can be propelled toward the outlet port. This, combined with the aforementioned fluid recirculation, enables the aircraft system to self-vent, wherein air bubbles contained in the hydraulic fluid within the hydraulic actuator during use can be transported from the hydraulic actuator along the outlet line. This self-venting mechanism allows the aircraft system to have a longer maintenance-free cycle.

[0009] The aircraft system can be configured such that: hydraulic fluid flowing along the inlet line toward the hydraulic actuator causes the hydraulic actuator to be activated, and hydraulic fluid flowing along the outlet line away from the hydraulic actuator causes the hydraulic actuator to be deactivated. This, for example, provides a relatively simple and / or inexpensive mechanism for recirculating hydraulic fluid within the hydraulic system compared to arrangements that require a pump to pump hydraulic fluid along the outlet line during use.

[0010] The aircraft system may include a control valve for controlling the flow of hydraulic fluid along an inlet line. This allows the hydraulic fluid to flow selectively along the inlet line. The control valve may be a servo valve or a proportional valve. The control valve may be configured such that applying a control signal to the control valve causes hydraulic fluid to flow along the inlet line toward the hydraulic actuator, and removing the control signal from the control valve causes hydraulic fluid to flow along the outlet line away from the hydraulic actuator. The control valve may also be configured such that removing the control signal from the control valve causes hydraulic fluid to flow along the outlet line away from the hydraulic actuator, and flow through the control valve, for example, toward and / or into a reservoir.

[0011] The inlet and outlet lines can be fluidly connected to the control valve. This provides a simpler and / or cheaper arrangement than a system where the inlet and outlet lines are connected to separate valves.

[0012] The inlet and outlet lines can be connected to the control valve via a shared conduit. This provides a simpler and / or cheaper arrangement than a system where the inlet and outlet lines are connected to the control valve via separate conduits.

[0013] The common conduit can have a first volume, and the aircraft system can be configured such that a maximum second volume of hydraulic fluid can be displaced along the outlet line via the hydraulic actuator in a single actuation, and the first volume can be smaller than the second volume. By making the first volume smaller than the second volume, recirculation of the hydraulic fluid from the outlet line can be facilitated. For example, if the first volume is larger than the second volume, there is a risk that the hydraulic fluid will simply remain in the common conduit instead of passing through the control valve, and once the hydraulic actuator is activated again, the same hydraulic fluid will be delivered along the inlet line toward the hydraulic actuator. Conversely, by making the first volume smaller than the second volume, the hydraulic fluid from the outlet line is forced through the common conduit and through the control valve.

[0014] A hydraulic actuator may include a plurality of pistons movable between a retracted position and an extended position. Each piston may be biased toward the retracted position. Each piston may be configured such that hydraulic fluid flowing along an inlet line causes the piston to move from the retracted position toward the extended position, for example, wherein the pistons are configured to act in parallel. The hydraulic actuator may include a chamber located on one side of each piston, and inlet and outlet lines may be in fluid communication with the chamber. The hydraulic actuator may include a single-acting hydraulic actuator.

[0015] The hydraulic actuator may include a first chamber and a first piston capable of moving within the first chamber in response to the movement of hydraulic fluid, with inlet and outlet lines in fluid communication with the first chamber. The hydraulic actuator may also include a second chamber and a second piston capable of moving within the second chamber in response to the movement of hydraulic fluid. The aircraft system may include: a second inlet line for supplying hydraulic fluid to the second chamber; a second outlet line for removing hydraulic fluid from the second chamber; a second first check valve configured to allow fluid to flow along the second inlet line in a direction toward the second chamber; and a second second check valve configured to allow fluid to flow along the outlet line in a direction away from the second chamber. This can provide a redundant dual-chamber arrangement for the hydraulic actuator.

[0016] The aircraft system may include a first hydraulic system comprising: a first pressure source for supplying hydraulic fluid to an inlet line; a first reservoir for receiving fluid from an outlet line; and a first control valve for controlling the flow of hydraulic fluid along the inlet and outlet lines. The inlet and outlet lines may be connected to the first control valve via a first common conduit. The first common conduit may have a first volume, and the aircraft system may be configured such that a second volume of hydraulic fluid is configured to flow through the first common conduit from the outlet line in response to the deactivation of a first piston, and the first volume may be smaller than the second volume.

[0017] The aircraft system may include a second hydraulic system comprising: a second pressure source for supplying hydraulic fluid to another inlet line; a second reservoir for receiving fluid from another outlet line; and a second control valve for controlling the flow of hydraulic fluid along the other inlet line and the other outlet line. The other inlet line and the other outlet line may be connected to the second control valve via a second common conduit. The second common conduit may have a first volume, and the aircraft system may be configured such that a second volume of hydraulic fluid is configured to flow through the second common conduit from the other outlet line in response to the deactivation of a second piston, and the first volume may be smaller than the second volume.

[0018] The aircraft system may include a first hydraulic system comprising a first pressure source, a first reservoir, and a first control valve for controlling the flow of hydraulic fluid from the first pressure source to an inlet line and for controlling the flow of hydraulic fluid from an outlet line to the first reservoir. The aircraft system may also include a second hydraulic system comprising a second pressure source, a second reservoir, and a second control valve for controlling the flow of hydraulic fluid from the first pressure source to an inlet line and for controlling the flow of hydraulic fluid from an outlet line to the first reservoir. The aircraft may include a selector for selecting which of the first and second hydraulic systems is fluidly connected. This provides redundancy without requiring additional inlet and outlet lines.

[0019] The selector may include a shuttle valve. Inlet and outlet lines can be connected to the shuttle valve via a common conduit. A first control valve can be connected to the shuttle valve via a first conduit, and a second control valve can be connected to the shuttle valve via a second conduit. The total volume of the common conduit, the first conduit, and the second conduit may be less than the volume of hydraulic fluid configured to displace from the hydraulic actuator during periods of inactivity.

[0020] The selector may include a first shuttle valve connected between a first control valve and a second control valve and in fluid communication with an inlet line, and a second shuttle valve connected between the first control valve and the second control valve and in fluid communication with an outlet line. This allows flow to be split between the first and second shuttle valves through the inlet and outlet lines. The first and second shuttle valves may be connected to the first control valve via a first common conduit, and to the second control valve via a second common conduit. The total volume of the first and second shuttle valves may be less than the volume of hydraulic fluid configured to displace from the hydraulic actuator during periods of inactivity.

[0021] The aircraft system may include a first control valve for controlling the flow of hydraulic fluid along the inlet line and a second control valve for controlling the flow of hydraulic fluid along the outlet line. This allows the hydraulic fluid to circulate without using the primary function of the hydraulic actuator.

[0022] The aircraft system may include a first hydraulic system comprising a first pressure source in fluid communication with a first control valve, a first reservoir in fluid communication with a second control valve, and a first control valve and a second control valve. The aircraft system may also include a second hydraulic system comprising a second pressure source, a second reservoir, another first control valve for controlling the flow of hydraulic fluid from the second pressure source to an inlet line, and another second control valve for controlling the flow of hydraulic fluid from an outlet line to a second reservoir. The aircraft system may include a first selector valve for selecting which of the first and second control valves is in fluid communication with the inlet line. The aircraft system may also include a second selector valve for selecting which of the second and second control valves is in fluid communication with the outlet line. This aircraft system allows hydraulic fluid to circulate without using the primary function of the hydraulic actuator, while also providing redundancy in situations where one of the first and second hydraulic systems is inoperable and / or operates with reduced functionality.

[0023] The hydraulic actuator may include a first chamber, a second chamber, and a piston capable of moving in response to hydraulic fluid flow through the first and second chambers. An inlet line and an outlet line are in fluid communication with the first chamber, and the aircraft system may include: a second inlet line for supplying hydraulic fluid to the second chamber; a second outlet line for removing hydraulic fluid from the second chamber; a second first check valve configured to allow fluid to flow along the second inlet line in a direction toward the second chamber; and a second check valve configured to allow fluid to flow along the outlet line in a direction away from the second chamber. This allows for the recirculation of hydraulic fluid in both the first and second chambers. The hydraulic actuator may include a double-acting hydraulic actuator.

[0024] The aircraft system may include a first hydraulic system comprising: a first pressure source for supplying hydraulic fluid to an inlet line; a first reservoir for receiving fluid from an outlet line; and a first control valve for controlling the flow of hydraulic fluid along the inlet and outlet lines. The inlet and outlet lines may be connected to the first control valve via a first common conduit. The volume of the first common conduit may be greater than the maximum volume of hydraulic fluid that can be displaced along the outlet line by the movement of a piston in a single actuation.

[0025] The aircraft system may include a second hydraulic system comprising: a second pressure source for supplying hydraulic fluid to another inlet line; a second reservoir for receiving fluid from another outlet line; and a second control valve for controlling the flow of hydraulic fluid along the other inlet and outlet lines. The other inlet and outlet lines may be connected to the second control valve via a second common conduit. The volume of the second common conduit may be greater than the maximum volume of hydraulic fluid that can be displaced along the other outlet line by piston movement in a single actuation.

[0026] The aircraft system can be an aircraft braking system, and the hydraulic actuator can be a hydraulic brake actuator. A typical hydraulic brake actuator may have a dead volume where no renewal of the hydraulic fluid is visible during normal operation. Implementing fluid recirculation in an aircraft braking system can distribute the aging of the hydraulic fluid more widely throughout the aircraft hydraulic system and can also provide improved thermal circulation in the manner previously described. In use, the control valve can operate in response to a braking signal, such as a braking input command received from the aircraft's pilot.

[0027] The aircraft system may include an aircraft brake, and the aircraft system may be configured such that hydraulic fluid flows along an inlet line toward a hydraulic actuator, causing the hydraulic actuator to be activated, thereby increasing the level of braking force applied by the aircraft brake, and the aircraft system may be configured such that hydraulic fluid flows along an outlet line away from the hydraulic actuator, causing the hydraulic actuator to be deactivated, thereby decreasing the level of braking force applied by the aircraft brake.

[0028] Aircraft brakes may include multi-disc brakes. The aircraft system may include wheels, and the aircraft brakes may be configured to selectively apply braking force to the wheels in response to the activation of a hydraulic actuator.

[0029] A second aspect of the invention provides a hydraulic actuator for an aircraft system, the hydraulic actuator including an inlet port and an outlet port, the inlet port being in fluid communication with an inlet line for supplying hydraulic fluid to the hydraulic actuator, and the outlet port being in fluid communication with an outlet line for removing hydraulic fluid from the hydraulic actuator, the inlet port being located on a first side of the hydraulic actuator, and the outlet port being located on a second side of the hydraulic actuator, the second side of the hydraulic actuator being different from the first side of the hydraulic actuator.

[0030] The first side of the hydraulic actuator can be configured such that when the hydraulic actuator is installed inside the aircraft in use and the aircraft is located on a horizontal surface, the first side of the hydraulic actuator is located below the second side of the hydraulic actuator.

[0031] The hydraulic actuator can be configured such that, when the hydraulic actuator is installed inside an aircraft in use and the aircraft is on a horizontal surface, the inlet port is located at the bottom of the hydraulic actuator and the outlet port is located at the top of the hydraulic actuator.

[0032] A third aspect of the invention provides an aircraft comprising an aircraft system according to a first aspect of the invention or a hydraulic actuator according to a second aspect of the invention.

[0033] Where appropriate, optional features of various aspects of the invention may be applied equivalently to other aspects of the invention. Attached Figure Description

[0034] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0035] Figure 1 A schematic diagram of the aircraft is shown;

[0036] Figure 2 A schematic diagram of the braking system of the first example aircraft is shown;

[0037] Figure 3 A schematic diagram of the piston of a hydraulic brake actuator is shown;

[0038] Figure 4 A schematic diagram of the braking system of the second example aircraft is shown;

[0039] Figure 5 A schematic diagram of the braking system of the third example aircraft is shown;

[0040] Figure 6 A schematic diagram of the braking system of the fourth example aircraft is shown;

[0041] Figure 7 A schematic diagram of the braking system of the fifth example aircraft is shown;

[0042] Figure 8 A schematic diagram of the braking system of the sixth example aircraft is shown; and

[0043] Figure 9 A schematic diagram of the braking system of the seventh example aircraft is shown. Detailed Implementation

[0044] Figure 1The image shows an aircraft 100. The aircraft 100 includes two main landing gears (“MLGs”) 100a and 100b and a nose landing gear (“NLG”) 100c. Each of the two main landing gears (“MLGs”) 100a and 100b and the nose landing gear (“NLG”) 100c includes a plurality of corresponding wheels 110a-110c. Each wheel 110a-110b of the MLGs 100a and 100b includes a brake 120 configured to apply braking force to the corresponding wheel 110a-110b. In this example, the wheel 110c of the NLG 100c does not include a corresponding brake. In other examples, the wheel 110c of the NLG 100c also includes a brake.

[0045] The aircraft 100 also includes a controller 102 that communicates with a brake lever 104 disposed in the cockpit 106 of the aircraft. The controller 102 is configured to provide a braking signal in response to the pilot's actuation of the brake lever 104 during use of the aircraft 100.

[0046] The brakes 120 of the aircraft 100 are hydraulically operated disc brakes, each of which includes a stack of rotor and stator discs positioned within the hubs of the respective wheels 110a-110b. As will be described in more detail below, in use, the rotor and stator discs are pressed together by a hydraulic brake actuator to generate friction between the rotor and stator discs.

[0047] Figure 2 The diagram schematically illustrates a first example aircraft braking system 10 for actuating brakes. It should be understood that in some examples, each wheel 110a-110b may have its own aircraft braking system, while in other examples, components of the aircraft braking system may be shared among the wheels 110a-110b of MLG 100a-100b.

[0048] The aircraft braking system 10 includes a hydraulic brake actuator 12, an inlet line 14, a first check valve 16, an outlet line 18, and a second check valve 20. Figure 2 In a specific example, the aircraft braking system 10 also includes a common conduit 21, a servo valve 22, a pressure source 24, and a reservoir 26. It should be understood that the brake 120 and the associated wheels 110a-110b can also be considered as part of the aircraft braking system 10. In some examples, the common conduit 21 may be located, for example, within the housing of the servo valve 22, thus forming part of the servo valve 22.

[0049] The hydraulic brake actuator 12 includes an inlet port 28, an outlet port 30, an internal flow path 32, and five pistons 34. The inlet port 28 is located on the upper side 36 of the hydraulic brake actuator 12, and the outlet port 30 is located on the lower side 38 of the hydraulic brake actuator 12. Therefore, when the hydraulic actuator... Figure 1 In the orientation shown, the inlet port 28 is located below the outlet port 30. This orientation can correspond to the orientation when the aircraft 100, including the aircraft braking system 10, is in use on a horizontal surface such as a runway.

[0050] The internal flow path 32 is in fluid communication with each of the inlet port 28 and the outlet port 30, and defines a corresponding chamber 40, within which a corresponding piston 34 is located, such as... Figure 3 The diagram is schematically illustrated. Each piston 34 is capable of moving within a chamber 40 of the piston 34 in response to the flow of hydraulic fluid through the internal flow path 32, as will be discussed in further detail below. Each piston 34 is biased by a spring 42 toward a stationary configuration, in which the volume of hydraulic fluid located within the corresponding chamber 40 is minimized. Each piston 34 within the hydraulic brake actuator 12, or even the hydraulic brake actuator 12 itself, can be considered a single-acting actuator.

[0051] The inlet line 14 is formed by a first conduit 44 which is fluidly connected to the common conduit 21 and the first check valve 16, and a second conduit 46 which is fluidly connected to the first check valve 16 and the inlet port 28. It should be understood that in practice, more or fewer conduits may be used to form the inlet line 14.

[0052] The first one-way valve 16 is a check valve that is oriented to allow fluid to flow from the common conduit 21 in the direction along the inlet line 14 toward the inlet port 28 of the hydraulic brake actuator 12, and is oriented to inhibit fluid from flowing in the opposite direction along the inlet line 14 away from the hydraulic brake actuator 12.

[0053] Similarly, the outlet line 18 is formed by a third conduit 48 which is fluidly connected to the common conduit 21 and the second check valve 20, and a fifth conduit 50 which is fluidly connected to the second check valve 20 and the outlet port 30. It should be understood that in practice, more or fewer conduits may be used to form the outlet line 18.

[0054] The second one-way valve 20 is a check valve that is oriented to allow fluid to flow from the outlet port 30 of the hydraulic brake actuator 12 in a direction away from the hydraulic brake actuator 12 and toward the common conduit 21, and is oriented to inhibit fluid from flowing in the direction toward the outlet port 30 of the hydraulic brake actuator 12 along the outlet line.

[0055] A common conduit 21 is connected to the servo valve 22 and is in fluid communication with each of the first conduit 44 of the inlet line 14 and the third conduit 48 of the outlet line 18. The volume of the common conduit 21 is less than the maximum volume of hydraulic fluid that can be displaced along the outlet line 18 in response to the deactivation of the hydraulic actuator 12, and the common conduit 21 is configured to carry bidirectional flow of hydraulic fluid in use, as will be discussed in further detail below. In other examples, the common conduit 21 may be integrated within the housing of the servo valve 22.

[0056] Servo valve 22 is fluidly connected to each of the common conduit 21, pressure source 24, and reservoir 26. The servo valve is configured to receive a control signal from the aircraft brake pedal and to control the flow of hydraulic fluid from pressure source 24 along inlet line 14 and from outlet line 18 into reservoir 26, as will be discussed in more detail below. Servo valve 22 can be considered a control valve in the context of this application.

[0057] Pressure source 24 includes a pump configured to pump hydraulic fluid toward servo valve 22 and along inlet line 14 during use. In some examples, the pump is in fluid communication with reservoir 26.

[0058] The reservoir 26 is a container configured to hold hydraulic fluid therein.

[0059] In use of the aircraft 100, the pilot applies force to the brake lever 104 to indicate the desired braking level, which causes a control signal to be sent to the controller 102. The controller 102 then sends a braking signal to the servo valve 22, and the servo valve operates to fluidly communicate the pressure source 24 with the common conduit 21. The pressure source 24 then causes hydraulic fluid to flow through the common conduit 21 and along the inlet line 14 toward the hydraulic brake actuator 12. The flow of hydraulic fluid along the inlet line 14 is sufficient to overcome the opening pressure of the first check valve 16, allowing the hydraulic fluid flowing along the inlet line 14 to pass through the inlet port 28 and enter the internal flow path 32 of the hydraulic brake actuator 12.

[0060] As hydraulic fluid flows along the internal flow path 32 of the hydraulic brake actuator 12, the hydraulic fluid causes each piston 34 to move within its respective chamber 40 against the action of a corresponding spring 42. The piston 34 presses the rotor and stator discs of the brake 120 together to generate friction between the rotor and stator discs, thereby causing braking of the associated wheels 110a-110b.

[0061] As hydraulic fluid flows along inlet line 14, second check valve 20 inhibits the flow of hydraulic fluid along outlet line 18 in the direction toward hydraulic brake actuator 12. The pressure differential across second check valve 20 also inhibits the flow of hydraulic fluid along outlet line 18 in the direction away from hydraulic brake actuator 12.

[0062] When the pilot releases the force applied to brake lever 104 or applies force to the brake lever in the opposite direction to the previously applied force to indicate a reduction in the desired braking level to be applied, such as no braking level to be applied, a new or modified control signal is sent to controller 102. Controller 102 then sends the new or modified braking signal to servo valve 22, and servo valve 22 operates to fluidly communicate reservoir 26 with common conduit 21.

[0063] When the pressure source 24 ceases to drive fluid along the internal flow path 32 of the hydraulic brake actuator 12, the spring 42 causes the corresponding piston 34 to orient itself toward its stationary configuration within the corresponding chamber 40. As the piston moves within the chamber 40, the hydraulic fluid is displaced relative to the chamber 40. The first check valve 16 inhibits the flow of hydraulic fluid along the inlet line 14 in a direction away from the hydraulic brake actuator 12, and thus inhibits the exit of hydraulic fluid from the hydraulic brake actuator 12 through the inlet port 28.

[0064] However, the second check valve 20 allows hydraulic fluid to flow along the outlet line 18 in a direction away from the hydraulic brake actuator 12. The hydraulic fluid thus exits the hydraulic brake actuator 12 through the outlet port 30 and proceeds along the outlet line 18 toward the common conduit 21. The pressure difference on the first check valve 16 inhibits the flow of hydraulic fluid along the inlet line 14 toward the hydraulic brake actuator 12. Therefore, the hydraulic fluid passes through the common conduit 21 and the servo valve 22 and proceeds toward the reservoir 26. Because the volume of the common conduit 21 is smaller than the maximum volume of hydraulic fluid that can be displaced along the outlet line 18 in response to the deactivation of the hydraulic actuator 12, the hydraulic fluid proceeds through the common conduit 21 toward the reservoir 26.

[0065] In this way, fluid recirculation via the hydraulic brake actuator 12 can be achieved. For example, fluid can circulate through the internal flow path 32 of the hydraulic actuator, wherein both the inlet line 14 and the outlet line 18 are in fluid communication with the internal flow path 32. This contrasts with known hydraulic brake actuators in aircraft braking systems, which typically exhibit a dead volume where no renewal of the hydraulic fluid is visible during normal operation. By providing fluid recirculation via the hydraulic brake actuator 12, the aging of the hydraulic fluid can be more widely distributed throughout the aircraft braking system 10, which could mean that such aging is more likely to be obtained by sampling the hydraulic fluid in the aircraft braking system 10. This can lead to a more predictable and / or more reliable state of the hydraulic fluid in the aircraft braking system 10. Fluid recirculation can also provide improved thermal cycling, for example, reducing the temperature of the hydraulic fluid contained within the aircraft braking system 10 during use.

[0066] Furthermore, because the inlet port 28 of the hydraulic brake actuator 12 is located at the bottom of the hydraulic brake actuator 12, and the outlet port 30 of the hydraulic brake actuator 12 is located at the top of the hydraulic brake actuator 12, any air bubbles in the hydraulic fluid within the hydraulic brake actuator 12 are forced to move toward the outlet port 30. When hydraulic fluid is allowed to flow along the outlet line 18 during use, such air bubbles are then discharged along the outlet line 18, thereby providing a self-venting mechanism for the hydraulic brake actuator 12. This can provide enhanced performance of the hydraulic brake actuator 12 and requires less maintenance, such as fewer venting operations, than a typical hydraulic brake actuator.

[0067] Although the above description indicates that the event occurs in response to the pilot's activation of brake lever 104, it should be understood that in other examples, another controller of the aircraft 100 may provide control signals to controller 102, or controller 102 may determine the braking signal itself based on one or more received sensor inputs. For example, the aircraft may include an anti-skid detection system, and controller 102 may be configured to determine an appropriate braking signal to provide anti-skid control to the relevant brakes.

[0068] Figure 4 The diagram schematically illustrates a second example aircraft braking system 200 for actuating the brakes. The second example aircraft braking system 200 includes a first hydraulic circuit 202, which has all the features of the first example aircraft braking system 10 except for a different hydraulic brake actuator 204, and for clarity... Figure 4The same reference numerals are used in the figures. The hydraulic brake 204 of the second example aircraft braking system 200 includes a first inlet port 206 and a second inlet port 208, a first outlet port 210 and a second outlet port 212, a first internal flow path 214 and a second internal flow path 216, and a first set of pistons 218 and a second set of pistons 220.

[0069] The first inlet port 206 is located at the bottom of the hydraulic brake actuator 204, and the first outlet port 210 is located at the top of the hydraulic brake actuator 204. The first inlet port 206 and the first outlet port 210 are in fluid communication with the first internal flow path 214, and each of the first set of pistons 218 is capable of moving within its respective individual chamber in response to the flow of hydraulic fluid against the action of a spring. The inlet line 14 of the first hydraulic circuit 202 is in fluid communication with the first inlet port 206, and the outlet line 18 of the first hydraulic circuit 202 is in fluid communication with the first outlet port 210.

[0070] The second inlet port 208 is located at the bottom of the hydraulic brake actuator 204, and the second outlet port 212 is located at the top of the hydraulic brake actuator 204. The second inlet port 208 and the second outlet port 212 are in fluid communication with the second internal flow path 216, and each of the second set of pistons 220 is capable of moving within its respective individual chamber in response to the flow of hydraulic fluid against the action of a spring. The hydraulic brake actuator 204 can be considered a dual-chamber hydraulic brake actuator.

[0071] The second example aircraft braking system 200 also includes a second hydraulic circuit 205, which includes another inlet line 222, another first check valve 223, another outlet line 224, another second check valve 225, another common conduit 226, another servo valve 228, another pressure source 230, and another reservoir 232. The details of the components of the second hydraulic circuit 205 are the same as the corresponding components of the first hydraulic circuit 202, and therefore, for the sake of brevity, will not be described further here except as described below.

[0072] Another inlet line 222 of the second hydraulic circuit 205 is fluidly connected to the second inlet port 208, while another outlet line 224 of the second hydraulic circuit 205 is fluidly connected to the second outlet port 212.

[0073] In the use of the second example aircraft braking system 200, a braking signal can be received from the aircraft's controller 102 by either servo valve 22 of the first hydraulic circuit 202 or another servo valve 228 of the second hydraulic circuit 205. This results in the first hydraulic circuit 202 actuating the first set of pistons 218, or the second hydraulic circuit 205 actuating the second set of pistons 220, wherein the operation occurs in the manner described above for the first example aircraft braking system 10.

[0074] Figure 5 The diagram schematically illustrates a third example aircraft braking system 300 for actuating the brakes. The third example aircraft braking system 300 is substantially the same as the first example aircraft braking system 10, except that it includes a shuttle valve 302, a first connecting conduit 304, a second connecting conduit 306, another servo valve 308, another pressure source 310, and another reservoir 312. For clarity, Figure 5 The same reference numerals are used in the figures.

[0075] In the third example aircraft braking system 300, servo valve 22, pressure source 24, and reservoir 26 can be considered to form a first hydraulic system 314, while another servo valve 308, another pressure source 310, and another reservoir 312 can be considered to form a second hydraulic system 316. Servo valve 22 is fluidly connected to shuttle valve 302 via a first connecting conduit 304, and another servo valve 308 is fluidly connected to shuttle valve 302 via a second connecting conduit 306. A common conduit 21 is fluidly connected to shuttle valve 302. The total volume of the common conduit 21, shuttle valve 302, and the first and second connecting conduits 304 is less than the maximum volume of hydraulic fluid that can be displaced along outlet line 18 in response to the deactivation of hydraulic actuator 12.

[0076] In the use of the third example hydraulic system 300, the shuttle valve 302 determines which of the first hydraulic system 314 and the second hydraulic system 316 is in fluid communication with the common conduit 21, and thus determines which of the first hydraulic system 314 and the second hydraulic system 316 is in fluid communication with the inlet line 14 or the outlet line 18. The shuttle valve 302 can therefore be considered a selector that chooses between the first hydraulic system 314 and the second hydraulic system 316. This arrangement can provide redundancy in cases where one of the first hydraulic system 314 or the second hydraulic system 316 is unavailable for operation.

[0077] Figure 6 The diagram schematically illustrates a fourth example aircraft braking system 400 for actuating brakes. Besides including a first shuttle valve 402 and a second shuttle valve 404, the fourth example aircraft braking system 400 is related to... Figure 5The third example aircraft braking system 300 is substantially the same. Again, for clarity, the same reference numerals are used. A first shuttle valve 402 is fluidly connected to the inlet line 14 and fluidly connected to each of the servo valve 22 and the other servo valve 308. Similarly, a second shuttle valve 404 is fluidly connected to the outlet line 18 and fluidly connected to each of the servo valve 22 and the other servo valve 308. The servo valve 22 and the first fluid volume 406 between the junction of the first shuttle valve 402 and the second shuttle valve 404, and the other servo valve 308 and the second fluid volume 408 between the junction of the first shuttle valve 402 and the second shuttle valve 404, define a total volume smaller than the maximum volume of hydraulic fluid that can be displaced along the outlet line 18 in response to the deactivation of the hydraulic actuator 12. This arrangement again provides redundancy while also allowing flow along the inlet line 14 and the outlet line 18 to pass through individual shuttle valves.

[0078] Figure 7 The diagram schematically illustrates a fifth example aircraft braking system 500 for actuating brakes. Except for the absence of a shared conduit 21, the presence of another servo valve 502, and the following, the fifth example aircraft braking system 500 is similar to... Figure 2 The first example aircraft braking system 10 is essentially the same. For clarity, in Figure 6 The same reference numerals are used in the figures. Servo valve 22 is fluidly connected to inlet line 14, and fluidly connected to each of pressure source 24 and reservoir 26. Another servo valve 502 is fluidly connected to outlet line 18, and fluidly connected to each of pressure source 24 and reservoir 26. The presence of servo valves on each line allows for the recirculation of hydraulic fluid even when braking is not in effect.

[0079] Figure 8 A sixth example aircraft braking system 600 for actuating brakes is schematically illustrated, wherein the same reference numerals are used for clarity. The sixth example aircraft braking system 600 is similar to the fifth example aircraft braking system 500, except that... Servo valve 22, another servo valve 502, pressure source 24, and reservoir 26 form a first hydraulic system 602. Servo valve 22 can be considered as the first servo valve, and the other servo valve 502 can be considered as the second servo valve. The sixth example aircraft braking system 600 includes a first shuttle valve 604, a second shuttle valve 606, and a second hydraulic system 608. The second hydraulic system 608 includes a third servo valve 610, a fourth servo valve 612, another pressure source 614, and another reservoir 616. The third servo valve 610 and the fourth servo valve 612 are each fluidly connected to the other pressure source 614 and the other reservoir 616.

[0080] The first shuttle valve 604 is fluidly connected to the inlet line 14 and to each of the first servo valve 22 and the third servo valve 610. The second shuttle valve 606 is fluidly connected to the outlet line 18 and to each of the second servo valve 502 and the fourth servo valve 612. The first shuttle valve 604 and the second shuttle valve 606 can be selected between the first hydraulic system 602 and the second hydraulic system 608 to provide redundancy, while also allowing flow along the inlet line 14 and the outlet line 18 to pass through individual shuttle valves. Furthermore, when either the first hydraulic system 602 or the second hydraulic system 608 is connected to the inlet line 14 and the outlet line 18, the servo valves 22, 502, 610, and 612 enable active recirculation of the hydraulic fluid.

[0081] Figure 9 The diagram schematically illustrates a seventh example aircraft braking system 700 for actuating brakes. The seventh example aircraft braking system 700 includes a hydraulic brake actuator 702, a first hydraulic system 704, and a second hydraulic system 706. The hydraulic brake actuator 702 is a double-acting hydraulic actuator and includes a piston 708 having an expansion chamber 710 and a retraction chamber 712 disposed on either side of the head of the piston 708. Each of the expansion chamber 710 and the retraction chamber 712 includes an inlet port 711 and an outlet port 713.

[0082] The first hydraulic system 704 includes a first inlet line 714, a first check valve 716, a first outlet line 718, a second check valve 720, a first common conduit 721, a first servo valve 722, a first pressure source 724, and a first reservoir 726. The first inlet line 714 is fluidly connected to the inlet port 711 of the expansion chamber 710 and fluidly connected to the first common conduit 721. The first check valve 716 is disposed along the first inlet line 714 and configured to allow fluid to flow toward the expansion chamber 710. The first outlet line 718 is fluidly connected to the outlet port 713 of the expansion chamber 710 and fluidly connected to the first common conduit 721. The second check valve 720 is disposed along the first outlet line 718 and configured to allow fluid to flow away from the expansion chamber 710.

[0083] The first servo valve 722 is fluidly connected to the first common conduit 721 and fluidly connected to the first pressure source 724 and the first reservoir 726.

[0084] The second hydraulic system 706 includes a second inlet line 728, a third check valve 730, a second outlet line 732, a fourth check valve 734, a second common conduit 736, a second servo valve 738, a second pressure source 740, and a second reservoir 742. The second inlet line 728 is fluidly connected to the inlet port 711 of the retraction chamber 712 and fluidly connected to the second common conduit 736. The third check valve 730 is disposed along the second inlet line 728 and configured to allow fluid to flow toward the retraction chamber 712. The second outlet line 732 is fluidly connected to the outlet port 713 of the retraction chamber 712 and fluidly connected to the second common conduit 736. The fourth check valve 734 is disposed along the second outlet line 732 and configured to allow fluid to flow away from the retraction chamber 712.

[0085] The second servo valve 738 is fluidly connected to the second common conduit 736 and fluidly connected to the second pressure source 738 and the second reservoir 740.

[0086] In use, each of the first hydraulic system 704 and the second hydraulic system 706 operates in a manner similar to that described above with respect to the first example aircraft braking system 10. In this way, the first hydraulic system 704 can be used to recirculate the hydraulic fluid passing through the expansion chamber 710, and the second hydraulic system 706 can be used to recirculate the hydraulic fluid passing through the retraction chamber 712. When hydraulic fluid flows into the expansion chamber 710 along the first inlet line 714, hydraulic fluid is allowed to flow out of the retraction chamber 712 along the second outlet line 732. Similarly, when hydraulic fluid flows into the retraction chamber 712 along the second inlet line 730, hydraulic fluid is allowed to flow out of the expansion chamber 710 along the first outlet line 718.

[0087] In each of the above embodiments, the hydraulic fluid in the chamber or flow path of the hydraulic brake actuator can be recirculated so that the hydraulic fluid in the chamber or flow path is renewed during use.

[0088] Although the above description is in the context of hydraulic brake actuators, it should be understood that the concepts described herein can be applied to other suitable hydraulic actuators, particularly those used on aircraft. For example, the concepts discussed herein can be applied to the hydraulic actuators of LGERS for aircraft.

[0089] It should be noted that, unless otherwise expressly stated, the term “or” as used herein shall be interpreted as “and / or”.

Claims

1. An aircraft system, the aircraft system comprising: Hydraulic actuator; An inlet line for supplying hydraulic fluid to the hydraulic actuator; An outlet line for removing the hydraulic fluid from the hydraulic actuator; A first check valve is configured to allow fluid to flow along the inlet line in the direction toward the hydraulic actuator. as well as A second check valve is configured to allow the fluid to flow along the outlet line in a direction away from the hydraulic actuator.

2. The aircraft system according to claim 1, wherein, The hydraulic actuator includes an inlet port in fluid communication with the inlet line and an outlet port in fluid communication with the outlet line. The inlet port is located on a first side of the hydraulic actuator, and the outlet port is located on a second side of the hydraulic actuator, which is different from the first side of the hydraulic actuator.

3. The aircraft system according to claim 2, wherein, The first side of the hydraulic actuator is configured such that when the aircraft system is installed inside the aircraft in use and the aircraft is located on a horizontal surface, the first side of the hydraulic actuator is located below the second side of the hydraulic actuator.

4. The aircraft system according to claim 2 or claim 3, wherein, The hydraulic actuator is configured such that, when the aircraft system is installed inside the aircraft in use and the aircraft is located on a horizontal surface, the inlet port is located at the bottom of the hydraulic actuator, and the outlet port is located at the top of the hydraulic actuator.

5. The aircraft system according to any one of the preceding claims, wherein, The aircraft system is configured such that: hydraulic fluid flowing along the inlet line toward the hydraulic actuator causes the hydraulic actuator to be activated, and hydraulic fluid flowing along the outlet line away from the hydraulic actuator causes the hydraulic actuator to be deactivated.

6. The aircraft system according to any one of the preceding claims, wherein, The aircraft system includes a control valve for controlling the flow of hydraulic fluid along the inlet line.

7. The aircraft system according to claim 6, wherein, The inlet and outlet pipelines are fluidly connected to the control valve.

8. The aircraft system according to claim 6 or claim 7, wherein, The inlet pipeline and the outlet pipeline are connected to the control valve via a common conduit.

9. The aircraft system according to claim 8, wherein, The shared conduit has a first volume, and the aircraft system is configured such that a maximum second volume of hydraulic fluid can be displaced along the outlet line via the hydraulic actuator in a single actuation, and the first volume is smaller than the second volume.

10. The aircraft system according to any one of the preceding claims, wherein, The hydraulic actuator includes a first chamber and a first piston capable of moving within the first chamber in response to the movement of hydraulic fluid, the inlet line and the outlet line being in fluid communication with the first chamber, and wherein, The hydraulic actuator includes a second chamber and a second piston capable of moving within the second chamber in response to the movement of a hydraulic fluid; and The aircraft system includes: Another inlet line is used to supply hydraulic fluid to the second chamber; Another outlet line is used to remove hydraulic fluid from the second chamber; Another first check valve, configured to allow fluid to flow along the other inlet line in a direction toward the second chamber; and Another second check valve, configured to allow fluid to flow along the outlet line in a direction away from the second chamber.

11. The aircraft system according to any one of claims 1 to 10, wherein, The aircraft system includes: A first hydraulic system, comprising a first pressure source, a first reservoir, and a first control valve, wherein the first control valve is used to control the flow of hydraulic fluid from the first pressure source to the inlet pipeline and to control the flow of hydraulic fluid from the outlet pipeline to the first reservoir; A second hydraulic system, comprising a second pressure source, a second reservoir, and a second control valve, wherein the second control valve controls the flow of hydraulic fluid from the first pressure source to the inlet line and controls the flow of hydraulic fluid from the outlet line to the first reservoir; and A selector is used to select which of the first hydraulic system and the second hydraulic system is in fluid communication.

12. The aircraft system according to any one of claims 1 to 6, wherein, The aircraft system includes a first control valve for controlling the flow of hydraulic fluid along the inlet line and a second control valve for controlling the flow of hydraulic fluid along the outlet line.

13. The aircraft system according to claim 12, wherein, The aircraft system includes: A first hydraulic system, the first hydraulic system including a first pressure source fluidly connected to the first control valve, a first reservoir fluidly connected to the second control valve, and the first control valve and the second control valve; The second hydraulic system includes a second pressure source, a second reservoir, another first control valve for controlling the flow of hydraulic fluid from the second pressure source to the inlet line, and another second control valve for controlling the flow of hydraulic fluid from the outlet line to the second reservoir. A first selection valve, configured to select which of the first control valves and the other first control valve is in fluid communication with the inlet line; and The second selector valve is used to select which of the second control valve and the other second control valve is in fluid communication with the outlet pipeline.

14. The aircraft system according to any one of claims 1 to 9, wherein, The hydraulic actuator includes a first chamber, a second chamber, and a piston, the piston being movable in response to hydraulic fluid flow through the first and second chambers, wherein the inlet line and the outlet line are in fluid communication with the first chamber, and the aircraft system includes: Another inlet line is used to supply hydraulic fluid to the second chamber; Another outlet line is used to remove hydraulic fluid from the second chamber; Another first check valve, configured to allow fluid to flow along the other inlet line in a direction toward the second chamber; and Another second check valve, configured to allow fluid to flow along the outlet line in a direction away from the second chamber.

15. The aircraft system according to any one of the preceding claims, wherein, The aircraft system is an aircraft braking system, and the hydraulic actuator is a hydraulic braking actuator.

16. The aircraft system according to claim 15, wherein, The aircraft system includes an aircraft brake, and the aircraft system is configured such that the flow of hydraulic fluid along the inlet line toward the hydraulic brake actuator causes the hydraulic brake actuator to be activated, thereby increasing the braking force level applied by the aircraft brake, and the aircraft system is configured such that the flow of hydraulic fluid along the outlet line away from the hydraulic brake actuator causes the hydraulic brake actuator to be deactivated, thereby decreasing the braking force level applied by the aircraft brake.

17. A hydraulic actuator for an aircraft system, the hydraulic actuator including an inlet port and an outlet port, the inlet port being in fluid communication with the inlet line for supplying hydraulic fluid to the hydraulic actuator, the outlet port being in fluid communication with the outlet line for removing hydraulic fluid from the hydraulic actuator, the inlet port being located on a first side of the hydraulic actuator, and the outlet port being located on a second side of the hydraulic actuator, the second side of the hydraulic actuator being different from the first side of the hydraulic actuator.

18. The hydraulic actuator according to claim 17, wherein, The first side of the hydraulic actuator is configured such that when the hydraulic actuator is installed inside the aircraft in use and the aircraft is located on a horizontal surface, the first side of the hydraulic actuator is located below the second side of the hydraulic actuator.

19. An aircraft comprising an aircraft system according to any one of claims 1 to 16 or a hydraulic actuator according to any one of claims 17 to 18.

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