Hydraulic system and method for an aircraft flight control system

A hydraulic system of an aircraft may include a system pump configured to provide hydraulic fluid to the hydraulic system at a first working pressure. The hydraulic system may further include a booster pump configured to supply hydraulic fluid to at least one boostable actuator at a second working pressure higher than the first working pressure. The boostable actuator may be operatively coupled to and configured to actuate at least one flight control surface of an aircraft.

FIELD

The present disclosure relates generally to the aircraft flight control systems and, more particularly, to a system and method of operating a hydraulic system of an aircraft flight control system.

BACKGROUND

Aircraft typically include a flight control system for directional and attitude control of the aircraft in response to commands from the flight crew or an autopilot. A flight control system may include a plurality of movable flight control surfaces such as ailerons for roll control, elevators for pitch control, and a rudder for yaw control. The flight control surfaces may also include various devices for altering the lift and/or drag characteristics of the wings including leading edge devices (e.g., slats), trailing edge devices (e.g., flaps), and spoilers. Movement of the flight control surfaces is typically effected by actuators that may be mechanically coupled to the flight control surfaces. In many aircraft, actuators for flight control surfaces are hydraulically-driven by one or more centralized hydraulic systems which typically operate at a fixed operating pressure.

Hydraulic systems for aircraft are typically designed such that the flight control surfaces can be actuated in a manner allowing the aircraft to perform maneuvers covering all corners of the flight envelope, including outlier flight conditions. An outlier flight condition may require deflection of a flight control surface to a relatively high deflection angle during the failure of a hydraulic system powering one of the actuators. For example, an outlier flight condition may require deflection of the ailerons in a manner allowing the aircraft to achieve a relatively high bank angle within several seconds despite the failure of one of the redundant aileron actuators. Such a large deflection angle may require relatively high actuation forces in the actuators.

One solution for achieving high actuation forces for outlier conditions includes adding another actuator to the flight control surface. For example, in the above-noted example, instead of using two actuators on the aileron, a third actuator may be added such that a high actuation force may be generated by two of the actuators in the event that the third actuator is incapacitated due to a failure of one of the hydraulic systems. Unfortunately, the addition of a third actuator adds weight and complexity to the aircraft due to the need to route three hydraulic systems to the aileron. Another solution for achieving high actuation forces for outlier conditions includes using tandem actuators having multiple pistons, which unfortunately also adds weight and complexity to the flight control system. A further solution is to increase the working pressure of each of the hydraulic systems operating a flight control surface. Unfortunately, increasing the working pressure of a hydraulic system requires an increase in the size of all components of the hydraulic system which also adds weight to the aircraft.

As can be seen, there exists a need in the art for a system and method for increasing the actuation force capability of flight control surface actuators with a minimal increase in weight and complexity.

SUMMARY

The above-noted needs associated with hydraulic systems for aircraft flight control systems are specifically addressed and alleviated by the present disclosure which provides a hydraulic system of an aircraft having a system pump, a booster pump, and a boostable actuator. The system pump may be configured to provide hydraulic fluid to the hydraulic system at a first working pressure. The booster pump may be configured to supply hydraulic fluid to at least one boostable actuator at a second working pressure higher than the first working pressure. The boostable actuator may be configured to actuate at least one flight control surface of an aircraft.

In a further embodiment, disclosed is a hydraulic system for an aircraft including a first boostable actuator and a second boostable actuator operatively coupled to an aileron of an aircraft. The hydraulic system may include a system pump configured to supply hydraulic fluid to the first boostable actuator and the second boostable actuator at a first working pressure. In addition, the hydraulic system may include a first booster pump and a second booster pump configured to increase the pressure of the supplied hydraulic fluid to a second working pressure higher than the first working pressure. The first booster pump and the second booster pump may the hydraulic fluid respectively to the first boostable actuator and the second boostable actuator at the second working pressure for actuating the aileron.

Also disclosed is a method of operating a hydraulic system of a flight control system of an aircraft. The hydraulic system may have a system pump configured to provide hydraulic fluid to the hydraulic system at a first working pressure. The method may include identifying, using a boost controller communicatively coupled to a booster pump, when an aircraft is commanded to perform a maneuver. In addition, the method may include activating, using the boost controller, the booster pump to provide hydraulic fluid to the boostable actuator at a second working pressure after determining that the boostable actuator operating under the first working pressure is incapable of actuating the flight control surface in a manner allowing the aircraft before may commanded maneuver. The method may also include supplying, using the booster pump, hydraulic fluid to the at least one boostable actuator at a second working pressure higher than the first working pressure. Additionally, the method may include actuating a flight control surface using the at least one boostable actuator operating at the second working pressure, and de-activating, using the boost controller, the booster pump such that the pressure of the hydraulic fluid supplied to the at least one boostable actuator decreases from the second working pressure.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes of illustrating various embodiments of the present disclosure, shown inFIG. 1is an aircraft100which may incorporate one or more examples of a hydraulic system152(e.g.,FIG. 2) having a boost function capability as disclosed herein. The aircraft100may include a fuselage102having an empennage104at an aft end of the fuselage102. The empennage104may include a vertical tail110having a rudder112and one or more horizontal tails106each having an elevator108. The rudder112and elevators108may form part of the flight control system150(e.g.,FIG. 2) of the aircraft100. The aircraft100may additionally include a pair of wings116extending outwardly from the fuselage102, and may include one or more propulsion units114. The flight control surfaces130of the wings116may include ailerons128, leading-edge devices120, trailing edge devices122, spoilers118(shown inFIG. 2), and/or other flight control surfaces130. The flight control surfaces130of the wings116may be operated separately and/or in conjunction with the flight control surfaces130(e.g., rudder112and elevators108) of the empennage104.

FIG. 2is a top view of an example of a wing116having a plurality of flight control surfaces130as part of the aircraft100flight control system150. The flight control surfaces130of the wing116may include the above-mentioned ailerons128, one or more leading-edge devices120(e.g., slats), one or more trailing edge devices122(e.g., flaps124, flaperons126), and one or more spoilers118(e.g., speedbrakes). Each one of the flight control surfaces130may be operated by one or more actuators164,200which may be fluidly coupled to one or more hydraulic systems152. AlthoughFIG. 2illustrates a single hydraulic system152fluidly coupled to the actuators164,200of the spoilers118and the aileron128, an aircraft100may include two or more hydraulic systems152. In some examples, a flight control surface130(e.g., an aileron128, a spoiler118) of an aircraft100may have two or more actuators164,200, each of which may be fluidly coupled to separate hydraulic systems152for redundancy.

As shown inFIG. 2, the hydraulic system152may include a system pump154for providing hydraulic fluid to the hydraulic system152at a first working pressure. In addition, the hydraulic system152may include a system reservoir162for storing hydraulic fluid at the first working pressure. The actuators of the hydraulic system152may include one or more boostable actuators200and one or more system actuators164(e.g., non-boostable actuators). In the present disclosure, the system actuators164may be limited to receiving hydraulic fluid at the first working pressure. The boostable actuators200may be fluidly coupled to one or more booster pumps206for providing hydraulic fluid at a second working pressure which is higher than the first working pressure. The boostable actuators200may operate under the first working pressure as the default pressure, and may momentarily operate under the second working pressure when the boost function is activated causing the booster pumps206to provide hydraulic fluid to the boostable actuators200at the second working pressure. When the boost function is deactivated, the boostable actuators200may return to operation under the first working pressure.

InFIG. 2, the system actuators164are shown coupled to the spoilers118, and a pair of boostable actuators200are coupled to the aileron128. However, the aileron128and/or any one or more of the spoilers118may be actuated by a combination of one or more system actuators164and one or more boostable actuators200. In this regard, the flight control system150of the aircraft100may include system actuators164and/or boostable actuators200may be coupled to any one or more of the flight control surfaces130including the leading-edge devices and/or the trailing edge devices122. In addition, other flight control surfaces130of the aircraft100may be actuated by system actuators164and/or boostable actuators200. For example, the rudder112(FIG. 1) may include one or more system actuators164and/or one or more boostable actuators200, and/or the elevators108(FIG. 1) may each include one or more system actuators164and/or one or more boostable actuators200. Although the booster pumps206inFIG. 2are shown located proximate the ailerons128, the booster pumps206may be positioned at any location in the aircraft100. In some examples, a booster pump206may be mounted to or integrated into a boostable actuator200of a flight control surface130such as an aileron128.

In some examples (e.g.,FIGS. 3, 4, and 6) described in greater detail below, the system pump154may provide hydraulic fluid at the first working pressure (e.g., the default working pressure) to both the system actuators164and the boostable actuators200for actuation of the flight control surfaces130during the majority of the operating time of the flight control system150. When the booster pump206is activated, hydraulic fluid may be provided to the boostable actuators200at a second working pressure while the system actuators164continue to be operated under the first working pressure. In other examples (e.g.,FIG. 5) described below, the system pump154may provide hydraulic fluid at the first working pressure only to the system actuators164, and not to the boostable actuators200. In such an example, a boostable actuator200may be configured as an electro-hydrostatic actuator (EHA) having a dedicated hydraulic system for actuating the boostable actuator200under the first working pressure as the default pressure, and momentarily increasing the pressure of the hydraulic fluid to the second working pressure when the boost function is activated.

In one example, the first working pressure of the hydraulic system152may be approximately 3000 psi, and the second working pressure may be approximately 5000 psi. However, the first working pressure may be provided in any range (e.g., from 100-3000 psi) for actuation of one or more flight control surfaces130of the flight control system150. Likewise, hydraulic fluid at the second working pressure may be provided by the booster pump206in any one of a variety of pressures higher than the first working pressure. For example, a booster pump206may be configured to provide hydraulic fluid at a second working pressure in the range of from approximately 5000-8000 psi. In still further examples, a booster pump206may be configured to provide hydraulic fluid at a second working pressure of greater than 8000 psi.

Advantageously, the booster pumps206and boostable actuators200of the presently-disclosed hydraulic system152may be actuated for flight conditions wherein the aircraft100requires a higher level of performance, and which may occur at outlier conditions in the corners of the flight envelope. For example, an outlier condition may require the momentary actuation of one or more flight control surfaces130using a relatively high actuation force to allow for adjustment of the deflection angle of the ailerons128. In such a scenario, one or more booster pumps206may be momentarily activated to provide hydraulic fluid at the second working pressure to a high-pressure side of one or more boostable actuators200for actuating the ailerons128. When the outlier condition is no longer present, the booster pump206may be passivated354(e.g., deactivated), and the one or more boostable actuators200may resume actuating the ailerons128at the first working pressure.

By including a boost function in the hydraulic system152to momentarily increase the working pressure of the hydraulic fluid to provide high actuation forces (e.g., to meet high control surface rate or hinge moment requirements), the actuators (e.g., hydraulic cylinders) may be sized for nominal flight conditions, reserving the boost function for flight conditions (e.g., outlier conditions of the flight envelope) requiring high actuation forces. In this manner, the hydraulic system152may be designed and operated using conventional, hydraulic system pressures (e.g., 3000 psi) which may increase reliability and reduce cost at the system level. Furthermore, the incorporation of the presently-disclosed boost function (e.g., via the addition of the booster pump206and boostable actuators200) into the hydraulic system152may avoid the need to increase the size of the hydraulic system components which may thereby enable the use of thin-wing airfoils with reduced aerodynamic drag relative to a larger wing section that would otherwise be required to house hydraulic components sized for high operating pressures (e.g., greater than 3000 psi). In addition, the incorporation of the presently-disclosed boost function into the hydraulic system152may enable a reduction or elimination of fairings or blisters that are conventionally used to cover protrusions of the hydraulic components outside of the outer mold line of the wing.

Although the presently-disclosed hydraulic system152and method is described in the context of a tube-and-wing aircraft100as shown inFIG. 1, the hydraulic system152and method may be implemented on any aircraft configuration, without limitation, including a blended wing configuration (not shown), a hybrid wing-body configuration (not shown), and other aircraft configurations. In addition, the presently-disclosed system and method may be implemented on any type of civil, commercial, and/or military aircraft, without limitation. Even further, the hydraulic system152and method may be implemented on any type of air vehicle, without limitation where boost function capability is required in one or more hydraulic systems152of a flight control system150for momentary actuation of a boostable actuator200at a second working pressure higher than the first working pressure under which the hydraulic system152operates.

FIG. 3shows an example of a hydraulic system152of an aircraft flight control system150. The hydraulic system152incorporates a booster pump206driven by a motor212controlled by a boost controller232. The boost controller232may be communicatively coupled to a ship-board data300connection for receiving aircraft state data302and/or actuator state data312on a continuous or periodic basis for regulating the operation of the motor212, as described in greater detail below. As indicated above, the hydraulic system152may include a system pump154configured to provide hydraulic fluid via nominal pressure supply lines156to one or more system actuators164(e.g., non-boostable actuators) at a nominal system pressure which is described herein as the first working pressure. The hydraulic system152may include nominal pressure return lines158for returning hydraulic fluid at the first working pressure to the system pump154. The hydraulic system152may additionally include a system reservoir162in the nominal pressure supply line156for storing hydraulic fluid.

In some examples, the system pump154may be a ship-board hydraulic pump which may be located in the fuselage102, the wing box, the wing116, or in another location remote from the boostable actuator200. The system pump154may provide hydraulic fluid at the first working pressure to the system actuators164and/or to one or more boostable actuators200. In one example, the system actuators164and/or the boostable actuators200may be configured as linear actuators having a piston slidable within a cylinder. However, in other examples not shown, one or more of the system actuators164and/or one or more of the boostable actuators200may be configured as rotary actuators such as rotary piston actuators or rotary vane actuators.

Referring still toFIG. 3, the booster pump206may be fluidly coupled to the boostable actuator200via a booster pressure supply line160. The booster pump206may be driven by a motor212(e.g., an electric motor or a hydraulic motor) that may be mechanically coupled to the booster pump206. The booster pump206may receive hydraulic fluid from the system pump154at the first working pressure. The boostable actuator200may be operatively coupled to a flight control surface130which is shown as an aileron128in the illustrated example. When the booster pump206is in a passivated or deactivated state, the boostable actuator200may operate under hydraulic fluid at the first working pressure. When the booster pump206is activated, the booster pump206may increase the pressure of the supplied hydraulic fluid from the first working pressure to the second working pressure, and may supply hydraulic fluid to the boostable actuator200at the second working pressure (e.g., a boosted system pressure). The hydraulic fluid at the second working pressure may be supplied to the boostable actuator200on either the extend side of the piston, or on the retract side of the piston as necessary to actuate the flight control surface130in the required direction according to the flight control command.

AlthoughFIG. 3illustrates a single booster pump206fluidly coupled to a single boostable actuator200, the booster pump206may be augmented by one or more additional booster pumps206for providing hydraulic fluid at the second working pressure to a single boostable actuator200coupled to a single flight control surface130, or multiple booster pumps206may provide hydraulic fluid at the second working pressure to a respective quantity of boostable actuators200coupled to the same flight control surface130. For example, as shown inFIG. 2, an aileron128may be actuated by a first boostable actuator202and a second boostable actuator204which may receive hydraulic fluid at the second working pressure from a first booster pump208and a second booster pump210, respectively.

Referring still toFIG. 3, the boost controller232may be communicatively coupled to the booster pump206via the motor212, and may receive aircraft state data302and/or actuator state data312via a ship-board data300connection for regulating the operation of the motor212, as described in greater detail below. The boost controller232may be programmed to activate the boost function (e.g., activate or operate the booster pump) in a manner providing hydraulic fluid to the boostable actuator200at the second working pressure. For example, the boost controller232may be programmed to identify when the aircraft100is commanded to perform a maneuver. In this regard, the aircraft100may receive a flight control command from the flight crew, from an autopilot, and/or from a remote control device (not shown) in the case that the aircraft is configured as a remotely-piloted aircraft such as a drone. Upon identifying that the aircraft100has been commanded to perform a maneuver, the boost controller232may activate the booster pump206(e.g., activate the boost function) in a manner causing the booster pump206to provide hydraulic fluid to the boostable actuator200at the second working pressure.

In some examples, the activation of the booster pump206may cause the booster pump206to increase the pressure of the hydraulic fluid from the first working pressure to the second working pressure. The boostable actuator200may receive the hydraulic fluid at the second working pressure and may actuate (e.g., reposition, further deflect, partially retract, or completely retract) the flight control surface130. The boostable actuator200may actuate the flight control surface130in a manner causing the aircraft100to perform the maneuver commanded. During or after the flight control surface130has been actuated by the boostable actuator200(e.g., after the aircraft100has completed the maneuver) at the second working pressure, the boost controller232may be programmed to deactivate the booster pump206such that the pressure of the hydraulic fluid provided to the boostable actuator200is reduced from the second working pressure (e.g., to the first working pressure).

In some examples, the boost controller232, upon identifying that the aircraft100has been commanded to perform a maneuver and prior to activating the booster pump206, may be programmed to determine whether the boostable actuator200acting under the first working pressure is capable of actuating a flight control surface130in a manner allowing the aircraft100to perform the maneuver as commanded. The boost controller232may be programmed to make the determination of whether the boostable actuator200is capable of actuating the flight control surface130based upon aircraft state data302of the aircraft100and/or based upon actuator state data312of one or more actuators (e.g., boostable actuators200) to which the flight control surface130may be coupled. In some examples, the aircraft state data302may include data regarding the current aircraft environment304such as the current airspeed306, altitude, attitude (e.g., roll angle, pitch angle, yaw angle), or other aircraft state data302that may be sensed by one or more aircraft sensors (not shown) and provided to the boost controller232on a continuous or periodic basis.

Alternatively or additionally, the aircraft state data302used by the boost controller232may include data regarding flight control commands from the flight crew such as via control column input308from the pilot (shown inFIGS. 9 and 10). Control column input308data may include data regarding the magnitude and/or rate of control column inputs308or equivalent (e.g., side stick inputs) for aircraft100that lack a control column. In some examples, the boost controller232may be programmed to determine the capability of the boostable actuator200to actuate a flight control surface130based on a control wheel input310commanded by the flight crew for roll control of the aircraft100, a control column displacement (e.g. fore/aft movement of the control column) for commanding pitch control of the aircraft100, a speedbrake control lever position for positioning the spoilers118, a flap lever setting for positioning the flaps124, an engine thrust lever setting, and other inputs.

As described in greater detail below, as shown inFIG. 8, the actuator state data312used by the boost controller232may also include data regarding whether the current actuator pressure314of the boostable actuator200is operating within a nominal actuator pressure314range. For example, if other actuators (e.g., system actuators164) fluidly coupled to the hydraulic system152are demanding flow and hydraulic pressure to the point that the hydraulic pressure available to the boostable actuator200is not within the nominal actuator pressure314range, then the booster pump206may be operated in a manner to temporarily increase the hydraulic pressure to the boostable actuator200. In an example of a 3000 psi hydraulic system, a nominal hydraulic pressure may be a pressure anywhere between 1200 psi and 3500 psi. If the nominal hydraulic pressure is lower than this range (e.g., lower than 1200 psi—the first working pressure for this example), then the boost function (e.g. the booster pump206) may increase the hydraulic pressure back up to a pressure (e.g., the second working pressure for this example) within the nominal hydraulic pressure314range, absent a detected leak or burst in a hydraulic line.

Referring still toFIG. 8, the aircraft state data302used by the boost controller232may also include information regarding whether the current actuator position316of the boostable actuator200is within a nominal actuator position316range. For example, if a pilot or autopilot commands one or more actuators (one or more boostable actuators200and/or one or more system actuators164) to a position but the actuator(s) fail to reach the commanded position, the boost function (e.g., the booster pump206) may provide additional hydraulic pressure to one or more boostable actuators200to enable the actuator(s) to reach the commanded position. The current actuator pressure314and the current actuator position316may be continuously or periodically monitored by one or more actuator sensors (not shown) that may be included with the system actuators164and/or the boostable actuators200. The actuator state data312used by the boost controller232may also include a prediction as to whether a boostable actuator200acting under the first working pressure will be incapable of meeting performance requirements based on the current aircraft environment304(e.g., aircraft state data302) including the nature (e.g., magnitude, rate) of a flight control command commanded by the flight crew, an autopilot, or via remote control. Such a prediction may be determined by actuator modeling318(e.g., computer modeling) of the boostable actuator200based on the current aircraft state data302and/or current actuator state data312.

FIG. 4shows an example of a hydraulic system152of a flight control system150similar to the arrangement shown inFIG. 3. However, inFIG. 4, the booster pump206is configured as a high-pressure accumulator216driven by an accumulator energizer218. The high-pressure accumulator216may receive hydraulic fluid from the system pump154at the first working pressure via a nominal pressure supply line156. The accumulator energizer218may be mechanically coupled to the high-pressure accumulator216by a mechanical coupling214such as a drive shaft friend not shown). The accumulator energizer218may be provided as an electric motor, a spring, or any other device capable of energizing or driving the high-pressure accumulator216.

InFIG. 4, the booster pump206may include a mode selection valve220fluidly coupled (e.g., via a boosted pressure supply line160) between the high-pressure accumulator216and the boostable actuator200. The mode selection valve220may receive hydraulic fluid at the first working pressure from the system pump154and may also receive hydraulic fluid at the second working pressure from the high-pressure accumulator216. The mode selection valve220may be selectively operated in a manner to provide hydraulic fluid to the boostable actuator200at either the first working pressure or at the second working pressure, depending upon whether the boost function has been activated.

For example, when activated by the boost controller232, the accumulator energizer218may increase the pressure of the hydraulic fluid in the high-pressure accumulator216from the first working pressure to the second working pressure. The boost controller232may operate the mode selection valve220such that instead of providing hydraulic fluid at the first working pressure to the boostable actuator200, the mode selection valve220is operated in a manner allowing the high-pressure accumulator216to supply hydraulic fluid to the boostable actuator200at the second working pressure. Activation of the boost controller232and the mode selection valve220to provide hydraulic fluid to the boostable actuator200at the second working pressure may occur based upon the aircraft state data302and/or the actuator state data312in a manner described below.

FIG. 5shows an example of a hydraulic system152wherein the booster pump206is configured as electro-hydrostatic actuator (EHA) pump222driven by a variable speed motor228. The variable speed motor228may be mechanically coupled to the EHA pump222. A booster reservoir230for storing hydraulic fluid may be fluidly coupled between the EHA pump222and the boostable actuator200. The EHA pump222may receive hydraulic fluid from the booster reservoir230. The EHA pump222, the variable speed motor228, the boostable actuator200, and optionally the booster reservoir230may collectively form an electro-hydrostatic actuator (EHA) which may function as an independent hydraulic system separate from the hydraulic system152supplying hydraulic fluid to other actuators (e.g., system actuators164) of the flight control system150. The EHA pump222may operate on ship-board power234(e.g., aircraft electrical power) received through a motor controller226via an electrical power line236. In addition, the motor controller226may be communicatively coupled to a ship-board data300connection for continuously or periodically receiving aircraft state data302and/or actuator state data312for regulating the operation of the variable speed motor228, as described in greater detail below.

The motor controller226may be communicatively coupled to the variable speed motor228for regulating the operation of the EHA pump222. When the boost function of the hydraulic system152is not activated, the motor controller226may be programmed to cause the variable speed motor228to rotate the EHA pump222in a manner (e.g., at a rotational speed) providing hydraulic fluid to the boostable actuator200at the first working pressure. When the boost function is activated, the motor controller226may be programmed to cause the variable speed motor228to increase the rotational speed of the EHA pump222in a manner to increase the pressure of the hydraulic fluid up to the second working pressure for supplying to the boostable actuator200. When the boost function is deactivated, the motor controller226may cause the variable speed motor228to reduce the rotational speed of the EHA pump222such that the hydraulic pressure provided to the boostable actuator200is reduced from the second working pressure to the first working pressure.

Referring still toFIG. 5, the motor controller226may be programmed to operate the variable speed motor228based upon the aircraft state data302and/or the actuator state data312. For example, in the event that a control wheel input310(e.g., for roll control via the ailerons128) commanded by the flight crew exceeds a threshold angle, the motor controller226may cause the variable speed motor228to increase the rotational speed of the EHA pump222so that the pressure of the hydraulic fluid provided to the boostable actuator200is increased from the first working pressure to the second working pressure. Additionally or alternatively, in the event that the control wheel input310(e.g., for roll control of the aircraft100via the ailerons128) commanded by the flight crew exceeds a threshold angle, and/or if the airspeed306of the aircraft100exceeds a threshold airspeed, the motor controller226may cause the variable speed motor228to increase the rotational speed of the EHA pump222so that hydraulic fluid is provided to the boostable actuator200at the second working pressure.

In a further example, if it is determined that the current actuator operating pressure of a second actuator (a system actuator164or a second boostable actuator204—not shown) coupled to the aileron128is below a threshold operating pressure, the motor controller226may cause the variable speed motor228to increase the rotational speed of the EHA pump222so that hydraulic fluid is provided to the boostable actuator200at the second working pressure. As may be appreciated, in any one of the hydraulic system152examples disclosed herein, there may be any one of a variety of different conditions based upon aircraft state data302and/or actuator state data312that trigger the activation of the boost function of the hydraulic system, and which may cause hydraulic fluid to be at least momentarily provided to the boostable actuator200at the second working pressure as a means to enable the flight control surface130to be actuated in a manner corresponding to a flight control command from the flight crew, an autopilot, by remote control, or as a result of an autonomous functionality of the flight control system150such as the above-mentioned maneuver load alleviation or gust load alleviation.

FIG. 6shows an example of a hydraulic system152wherein the booster pump206is configured as an electric backup hydraulic actuator (EBHA) pump224driven by a variable speed motor228. The variable speed motor228may be mechanically coupled to the EBHA pump224which may include a hydraulic stage (not shown) and an electric stage (not shown). A booster reservoir230may be fluidly coupled between the EBHA pump224and the boostable actuator200. A mode selection valve220may be fluidly coupled between the EBHA pump224and the boostable actuator200. The mode selection valve220may receive hydraulic fluid at the first working pressure from the system pump154, and may receive hydraulic fluid at the second working pressure from the EBHA pump224. The mode selection valve220may be operated to selectively provide hydraulic fluid to the boostable actuator200at either the first working pressure or the second working pressure.

The EBHA pump in combination with the variable speed motor228, the boostable actuator200, and optionally the booster reservoir230may collectively form an electric backup hydraulic actuator which may be operated independent of the hydraulic system152. The variable speed motor228may be regulated by the motor controller226. The motor controller226may receive electrical power from a connection to ship-board power234via an electrical power line236. In addition, the motor controller226may be communicatively coupled to ship-board data300for receiving aircraft state data302and/or actuator state data312for regulating the operation of the variable speed motor228.

Under nominal conditions, the motor controller226may control the mode selection valve220such that hydraulic fluid at the first working pressure from the system pump154is provided to the boostable actuator200. When the boost function is activated350by the motor controller226, the motor controller226may operate the mode selection valve220and the variable speed motor228in a manner causing the EBHA pump224to provide hydraulic fluid to the boostable actuator200at the second working pressure. In this regard, the EBHA pump224may be operated such that the summed output of the hydraulic stage and the electric stage pressurizes the hydraulic fluid to the second working pressure for delivery to the boostable actuator200.

The motor controller226may be programmed to operate the variable speed motor228and the mode selection valve220in a manner causing the EBHA pump224to supply hydraulic fluid at the second working pressure to the boostable actuator200for any one of a variety of different conditions requiring boost function. For example, such conditions may include a control wheel input310exceeding a threshold angle, an airspeed306exceeding a threshold airspeed, and/or the current actuator operating pressure of a second actuator (not shown) being below a threshold operating pressure. As indicated above with regard to the description ofFIG. 5, a second actuator (a system actuator164or a second boostable actuator) may be described as another actuator coupled to same flight control as the boostable actuator200.

FIG. 7shows a flowchart having one or more operations that may be included in an example of a method400of operating a hydraulic system152of a flight control system150having boost function capability. Step402of the method400may include identifying, using a boost controller232(e.g.,FIGS. 3-4) or a motor controller226(e.g.,FIG. 5-6), when an aircraft100is commanded to perform a maneuver. As indicated above, a flight control command may be initiated by the flight crew, by an autopilot, and/or by a remote control device. A command may also be described as an autonomous function performed by the flight control system150such as the above-described gust load alleviation or maneuver load alleviation during which one or more flight control surfaces130(e.g., the ailerons128) may be momentarily adjusted in a manner to reduce structural loads on the wings116in the event that the aircraft100encounters turbulence or wind gusts, and/or when the aircraft100is performing a maneuver that may subject the airframe (e.g., the wings116) to relatively high structural loads.

Step404of the method400may include determining whether the boostable actuator200operating under the first working pressure is capable actuating the flight control surface130in a manner causing the aircraft100to perform the maneuver as commanded. The determination as to whether the boostable actuator200is capable of actuating the flight control surface130may be based upon aircraft state data302and/or actuator state data312, as mentioned above. In some examples, Step404may be performed after determining that the aircraft100has been commanded to perform a maneuver. The determination as to whether the boostable actuator200is capable of actuating the flight control surface130may be based on the capability of the boostable actuator200acting alone under the first working pressure, or may be based on the capability of the boostable actuator200operating under the first working pressure in combination with one or more additional actuators acting under the first working pressure, and which may be coupled to the same flight control surface130as the boostable actuator200. In addition, the determination may be based upon the nature of the command including, but not limited to, the commanded actuator setting (e.g., the magnitude of the commanded deflection angle) of the flight control surface130, and/or the determination may be based upon the commanded actuation rate of the flight control surface130.

FIG. 8shows an example of a boost function logic flow350diagram for determining whether to activate the boost function capability (e.g., activate the booster pump) of the hydraulic system152. The determination may be performed by the boost controller232(e.g.,FIG. 3) and may be based upon actuator state data312that may be continuously or periodically provided to the boost controller232, and may include the current actuator pressure314of the boostable actuator200, the current actuator position316of the boostable actuator200, and/or actuator modeling318predicting the performance capability of the boostable actuator200. InFIG. 8, if the current actuator pressure314of the boostable actuator200falls outside of a nominal actuator pressure range, and/or if the current actuator position316of the boostable actuator200falls outside of a nominal actuator position range, and/or if computer modeling of the boostable actuator200predicts the inability of the boostable actuator200to perform the commanded maneuver based upon the current aircraft environment304or the nature of the flight control command, then the logic flow diagram considers boost function data356. In considering boost function data356, the boost controller232may review a time history of the boost function performance to determine whether any prior faults occurred. If no prior faults occurred during activation of a previous boost function of the hydraulic system152, and if at least one of the above-described actuator conditions regarding actuator pressure314, actuator position316, and actuator modeling318is true, then the boost function (e.g., the booster pump) may be activated350, as indicated in block352ofFIG. 8, and illustrated by the boost function logic flow outcome366.

Activation of the boost function may entail activation and/or operation of the booster pump206in Step406in a manner providing hydraulic fluid to the boostable actuator200at the second working pressure, as described below. In this regard, Step406may include using the boost controller232to activate the booster pump206to provide hydraulic fluid to the boostable actuator200at the second working pressure. The method may include mechanically driving the booster pump206using an electric motor or a hydraulic motor. In some examples, the method may include receiving, at the booster pump206, hydraulic fluid from the system pump154at the first working pressure, and increasing the pressure of the supplied hydraulic fluid from the first working pressure to the second working pressure using the booster pump206. The booster pump206may be activated after determining that the boostable actuator200and/or any other actuator (e.g., a system actuator164or a second boostable actuator) acting alone or in conjunction with the boostable actuator200operating under the first working pressure is incapable of actuating the flight control surface130. If the boost function is not activated, then the default is that the boost function remains in a passivated354state, which may correspond to hydraulic fluid being provided to the boostable actuator200at the first working pressure.

FIG. 9is an example of a boost function logic flow350diagram for determining whether to activate the booster pump206of the hydraulic system152illustrated inFIGS. 3, 5, and6. The boost function logic flow350diagram may be based on inputs of aircraft state data302and/or actuator state data312which, as indicated above, may be continuously or periodically provided to the boost controller232via a connection to the ship-board data300. In the example shown, the motor controller226may be programmed to determine whether the boostable actuator200operating under the first working pressure is capable of actuating the flight control surface130in a manner causing the aircraft100to perform a maneuver as commanded. The motor controller226may make the determination based upon aircraft state data302regarding the aircraft environment304such as (1) whether a control wheel input310(e.g., a turn angle of the control wheel) exceeds a threshold angle, and (2) whether an airspeed306exceeds a threshold airspeed. If the above two conditions are both true, and/or if the actuator operating pressure of a second actuator coupled to the flight control surface130is below a threshold operating pressure, then the motor controller226may determine whether prior faults occurred (e.g., in the hydraulic system152and/or in the booster motor212and/or associated components) during a previously-activated boost function. If no prior faults occurred, then the motor controller226may be programmed to activate or operate the motor212(e.g.,FIG. 3; or the variable speed motor228ofFIGS. 5-6) and/or the booster pump206(e.g.,FIG. 3; or the EHA pump222ofFIG. 5; or the EBHA pump224and mode selection valve220ofFIG. 6), as indicated in block358ofFIG. 9, and as shown by the boost function logic flow outcome366. Activation of the boost function may result in the booster pump206providing hydraulic fluid to the boostable actuator200at the second working pressure, as described below. If not activated, then the boost function may remain in a passivated354state, which may correspond to the booster pump206continue to provide hydraulic fluid to the boostable actuator200at the first working pressure.

For the hydraulic system152shown inFIG. 4, the step of determining whether to activate the high-pressure accumulator216(e.g., the booster pump) may be performed according to the boost function logic flow350diagram shown inFIG. 10. The determination of whether to activate the high-pressure accumulator216may be based upon aircraft state data302and/or actuator state data312, in a manner similar toFIG. 9. The step of activating the booster pump206(FIG. 4) may include receiving, at the high-pressure accumulator216, the hydraulic fluid from the system pump154at the first working pressure, and driving the high-pressure accumulator216using the accumulator energizer218to increase the pressure of the hydraulic fluid in the high-pressure accumulator216from the first working pressure to the second working pressure. In addition, the method may include receiving, at a mode selection valve220, hydraulic fluid at the first working pressure from the system pump154and hydraulic fluid at the second working pressure from the high-pressure accumulator216. If the boost function is activated as indicated by the boost function logic flow outcome366ofFIG. 10, the boost controller232may operate the mode selection valve220and the high-pressure accumulator216causing the release of hydraulic fluid to the boostable actuator200at the second working pressure, as indicated in block362ofFIG. 10. If not activated, the high-pressure accumulator216and the mode selection valve220may remain passivated as indicated in block364ofFIG. 10, and which may entail operation of the mode selection valve220in a manner such that hydraulic fluid is provided to the boostable actuator200at the first working pressure.

For the hydraulic systems152shown inFIGS. 5-6, the step of activating the booster pump206may include activating or operating the variable speed motor228using the motor controller226. As shown, the variable speed motor228may be mechanically coupled to the EHA pump222inFIG. 5, or to the EBHA pump224inFIG. 6. The EHA pump222inFIG. 5may receive hydraulic fluid from the booster reservoir230. The EBHA pump224inFIG. 6may receive hydraulic fluid at the first working pressure from the system pump154. The step of activating the booster pump206may include rotating the EHA pump222or EBHA pump224using the variable speed motor228in a manner to increase the pressure of the hydraulic fluid up to the second working pressure.

Step408of the method400may include supplying, using the booster pump206, hydraulic fluid to the boostable actuator200at the second working pressure which is higher than the first working pressure. For the hydraulic system152shown inFIG. 4, the method may include using the boost controller232to operate the mode selection valve220in a manner causing hydraulic fluid to be provided to the boostable actuator200at the second working pressure. For the hydraulic system152shown inFIG. 6, the method may include using the motor controller226to operate the mode selection valve220to cause hydraulic fluid to be provided to the boostable actuator200at the second working pressure.

Step410of the method400may include actuating the flight control surface130using the boostable actuator200operating with the hydraulic fluid at the second working pressure. The flight control surface130may be actuated in a manner causing the aircraft100to at least initiate the maneuver as commanded and/or at least partially perform the maneuver as commanded. In the present example, the step of actuating the flight control surface130may include actuating an aileron128using the boostable actuator200at the second operating pressure. However, as indicated above, the boostable actuator200or any combination of boostable actuators200may be operated to actuate any type of flight control surface130, without limitation. For example, one or more boostable actuators200may be operated to actuate one or more spoilers118, one or more wing leading edge devices120(e.g., slats), one or more wing trailing edge devices122such as flaps124or flaperons126, one or more tail surfaces such as an elevator108of a horizontal tail106or a rudder112of a vertical tail110, or other flight control surfaces.

Step412of the method400may include de-activating the boost function of the boostable actuator200using the boost controller232. For example, as indicated above, the step of deactivating the boost function may include operating the booster pump206such that the pressure of the hydraulic fluid supplied to the boostable actuator200is decreased from the second working pressure to the first working pressure. The step of deactivating the boost function may be performed during or after the flight control surface130has been actuated by the boostable actuator200at the second working pressure in a manner causing the aircraft100to at least initiate the performance of the maneuver commanded. In other examples, the boost function may be deactivated after the aircraft100has completed the maneuver.

Additional modifications and improvements of the present disclosure may be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present disclosure and is not intended to serve as limitations of alternative embodiments or devices within the spirit and scope of the disclosure.