Actuator

The present disclosure relates to a mechanical actuator having a modified locking mechanism and fewer components. The actuator has a cylinder, a locking recess formed on an interior wall of the cylinder, and a piston assembly that moves between an extended position and a retracted position responsive to fluid pressure within the cylinder. A lock is connected to the piston assembly and moves radially between a locked position and an unlocked position responsive to the fluid pressure within the cylinder.

TECHNICAL FIELD

The present disclosure relates generally to aircraft flight control systems, and more particularly to actuators configured to control a flight control member of an aircraft.

BACKGROUND

Aircraft include one or more movable flight control members allowing pilots and/or on-board systems to adjust and control the attitude of the aircraft during flight. Some typical flight control members found on aircraft include, but are not limited to, ailerons on the wings for roll control, elevators on the horizontal tail of the empennage for pitch control, a rudder on the vertical tail of the empennage for yaw control, as well as various other movable control surfaces.

The movement of flight control members is typically effected by one or more actuators mechanically coupled between a base on the aircraft (e.g., a wing spar) and the flight control member. Generally, such actuators operate hydraulically and are a supplier designed part. However, because of their complex design and large number of different parts, the manufacture and servicing of conventional actuators is not very economical. Particularly, conventional actuator designs call for a large number of different parts manufactured from a variety of different metals and metal alloys. Not only does this make conventional actuators more expensive and complex to manufacture and maintain, but it also causes long waiting periods for servicing and increased turnaround time. There is a desire to address these issues associated with conventional actuators for flight control members.

BRIEF SUMMARY

Aspects of the present disclosure relate to a mechanical actuator having an improved locking mechanism and fewer components. Because of these aspects, actuators configured according to the present disclosure are less complex than conventional actuators, and cheaper to manufacture and maintain. Further, the waiting periods related to servicing such actuators are decreased, as is the turnaround time, thereby helping to address issues associated with conventional actuators.

Accordingly, in one aspect of the present disclosure, an actuator for a flight control member comprises a cylinder, one or more locking recesses formed on an interior wall of the cylinder, a piston assembly disposed within the cylinder and configured to move between a retracted position and an extended position responsive to fluid pressure within the cylinder, and a locking mechanism connected to the piston assembly. The locking mechanism comprises one or more locks. Each lock is configured to move radially between a locked position in which the lock engages a corresponding locking recess, and an unlocked position in which the lock disengages the corresponding locking recess, responsive to the fluid pressure within the cylinder. A biasing member for each lock is configured to radially bias the lock into the locked position when the fluid pressure within the cylinder is less than a predetermined fluid pressure.

In one aspect, the actuator further comprises an extension port through which the fluid enters the cylinder to move the one or more locks radially to the unlocked position, and a retraction port through which the fluid enters the cylinder to move the piston assembly to the retracted position.

In one aspect, each of the one or more locks move radially to the unlocked position when the fluid pressure at the extension port is not less than the predetermined fluid pressure. Further, each of the one or more locks is biased radially to the locked position when the fluid pressure at the extension port is less than the predetermined fluid pressure.

In one aspect, the piston assembly comprises a piston head and a piston rod connected to the piston head.

In one aspect, the piston head is a monolithic member and comprises a piston body section, a piston cap section, a support section positioned axially between the piston body section and the piston cap section, and one or more cavities formed between the piston cap section and the piston body section.

In one aspect, the one or more locks move radially within the one or more cavities between the locked and unlocked positions.

In one aspect, each biasing member is disposed within a corresponding cavity between the support section and a corresponding lock of the one or more locks.

In one aspect, the actuator further comprises a castle nut threadably engaged with the cylinder proximate one end of the actuator. The castle nut comprises a central bore configured to receive the piston rod therethrough.

In one aspect, the castle nut is a monolithic member and further comprises a scraper assembly and a scraper configured to contact the piston rod as the piston rod moves within the central bore.

In one aspect, the castle nut further comprises one or more channels formed thereon, with each channel sized to receive a corresponding gasket.

In one aspect, the castle nut further comprises a first gasket seated in a first channel and configured to form a seal between an interior wall of the castle nut and the piston rod, and a second gasket seated in a second channel and configured to form a seal between an exterior wall of the castle nut and an interior wall of the cylinder.

In another aspect, of the present disclosure, a method of operating an actuator for a flight control member is provided. In this aspect, the method calls for moving a piston assembly disposed within a cylinder of the actuator between a retracted position and an extended position responsive to fluid pressure within the cylinder, moving one or more locks connected to the piston assembly radially between a locked position in which each of the one or more locks engages a corresponding locking recess formed on an interior wall of the cylinder, and an unlocked position in which each of the one or more locks disengages the corresponding locking recess, responsive to the fluid pressure within the cylinder, and radially biasing the lock into the locked position when the fluid pressure within the cylinder is less than a predetermined fluid pressure.

In one aspect, radially moving the one or more locks between the locked position and the unlocked position comprises supplying the cylinder with hydraulic fluid via an extension port such that when the fluid pressure at the extension port reaches the predetermined fluid pressure, the one or more locks move radially to the unlocked position.

In one aspect, each of the one or more locks moves radially within a cavity formed on an interior of a piston head of the piston assembly between the locked position and the unlocked position.

In one aspect, each of the one or more locks are radially biased within the cavity towards the corresponding locking recess formed on the interior wall of the cylinder.

In one aspect, the method further comprises threadably engaging the cylinder with a monolithic castle nut proximate one end of the actuator.

In one aspect, the method further comprises the monolithic castle nut scraping a piston rod connected to the piston head as the piston rod moves through a central bore formed in the monolithic castle nut.

In another aspect of the present disclosure, a vehicle comprises one or more actuators. In this aspect, each actuator comprises a cylinder, one or more locking recesses formed on an interior wall of the cylinder, a piston assembly disposed within the cylinder, and configured to move between a retracted position and an extended position responsive to fluid pressure within the cylinder, and a locking mechanism connected to the piston assembly. The locking mechanism comprises one or more locks, each lock configured to move radially between a locked position in which the lock engages a corresponding locking recess, and an unlocked position in which the lock disengages the corresponding locking recess, responsive to the fluid pressure within the cylinder, and a biasing member for each lock. The biasing member is configured to radially bias the lock into the locked position when the fluid pressure within the cylinder is less than a predetermined fluid pressure.

In one aspect, the actuator further comprises an extension port through which the fluid enters the cylinder to move the one or more locks radially to the unlocked position, and a retraction port through which the fluid enters the cylinder to move the piston assembly to the retracted position.

In one aspect, the vehicle is an aircraft. In these aspects, at least one of the one or more actuators is disposed on a flight control member of the aircraft.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to a mechanical actuator having an improved locking mechanism and fewer components, compared to conventional actuators. Particularly, in one aspect, an actuator configured according to the present disclosure has a cylinder, a locking recess formed on an interior wall of the cylinder, and a piston assembly that moves between an extended position and a retracted position responsive to fluid pressure within the cylinder. A lock is connected to the piston assembly and moves radially between a locked position and an unlocked position responsive to the fluid pressure within the cylinder. In the locked position, a biasing member radially biases the lock towards the locking recess such that the lock engages the locking recess. So engaged, the lock prevents movement of the piston assembly within the cylinder. In the unlocked position, the lock disengages from the locking recess, thereby allowing the piston assembly to move within the cylinder.

Actuators configured according to the present disclosure create or contribute to a system that provides significant benefits over conventional actuators by reducing the number of component parts used to build such actuators. Particularly, fewer component parts reduce the complexity of the actuators, thereby resulting in a significant cost savings in the manufacture and maintenance of the actuators. Additionally, fewer component parts reduce the weight of a vehicle that utilizes the actuators. This means that the cost to operate the vehicle is also positively affected.

Turning now to the drawings,FIG. 1illustrates an aircraft10configured with one or more actuators according to one aspect of the present disclosure. As seen inFIG. 1, aircraft10comprises a pair of wing members12a,12b(collectively, wings12) and a tail section14connected to a fuselage16. A plurality of different types of flight control members18a,18b,18c(collectively, flight control members18) are distributed on aircraft10. By way of non-limiting example, the flight control members18can be disposed on wings12or the tail section14, and can include but are not limited to a rudder, elevators, ailerons, wing leading and trailing edge devices, and spoilers. According to aspects of the present disclosure, the flight control members18are movably attached to aircraft10. During flight, pilots and/or control systems on board aircraft10change the orientation of the flight control members18using actuators configured according to the present disclosure to adjust and control the attitude of the aircraft.

FIG. 2is a top view of wing12aillustrating possible placements on aircraft10for one or more actuators30configured to control movement of a flight control member18aaccording to one aspect of the present disclosure. As will be readily appreciated by those of ordinary skill in the art, the particular positioning of the actuators30on wing12ais for illustrative purposes only. Indeed, in other aspects, the actuators30may be disposed on parts of aircraft10other than wing12a, such as on wing12band/or tail section14, for example, as well as in other positions and orientations. Regardless of the particular placement and orientation, however, actuators30are disposed between a support structure20of aircraft10and flight control member18asuch that actuators30control the movement of the flight control member18a.

FIGS. 3A-3Dare cut-away views of an actuator30configured according to one aspect of the present disclosure. In particular,FIG. 3Aillustrates actuator30in a retracted position andFIG. 3Billustrates actuator30in an extended position.FIGS. 3C-3Dare close-up views of actuator30illustrating an internal structure of actuator30according to the present aspects.

As seen inFIGS. 3A-3D, an actuator30configured according to aspects of the present disclosure comprises a cylinder32having an internal chamber34. One or more locking recesses36a,36b,36c(collectively, locking recesses36) are formed on an interior wall38of cylinder32. In one aspect (FIG. 3C), actuator30comprises a plurality of locking recesses36a,36bformed on the interior wall38. In this aspect, each locking recess36a,36bis formed independently and is spaced-apart from the other locking recess36a,36b. In another aspect, however (FIG. 3D), actuator30comprises a single locking recess36cformed on the interior wall38of cylinder32as an annular channel or race. Regardless of the particular structure of the locking recesses36, however, a piston assembly130is disposed within cylinder32, and is configured to move between the retracted position seen inFIG. 3Aand the extended position seen inFIG. 3Bresponsive to fluid pressure in chamber34. One end41of the actuator30comprises a first connecting member40configured to fixedly attach actuator30to a support structure20on aircraft10.

The piston assembly130comprises a piston head50and a piston rod70. One end71aof piston rod70is connected to piston head50. The opposite end71bof piston rod70has a connection member72configured to attach to a flight control member18on aircraft10. As the piston assembly130moves between the extended and retracted positions, the connection member72moves the flight control member18accordingly.

In this aspect of the present disclosure, piston head50is a monolithic member comprising a piston body section52, a piston cap section54, and a support section56positioned axially between the piston body section52and the piston cap section54. The piston head50also comprises a locking mechanism140that includes one or more locks60a,60b,60c(collectively, locks60), a biasing member61for each lock60, one or more cavities58, and a gasket62disposed between the piston body section52and the interior wall38of cylinder32. As seen inFIGS. 3C-3D, the number and structure of locks60, and of the one or more cavities58, may depend on the number and structure of locking recesses36. In one aspect, when actuator30is formed to include a plurality of locking recesses36a,36b, actuator30comprises a plurality of corresponding locks60a,60b—one lock for each cavity and locking recess (FIG. 3C). In another aspect, however, actuator30comprises a single lock60c(FIG. 3D). In these aspects, the single lock60chas a “slit” cut into it that allows the lock60cto be squeezed when not engaged with the locking recess36c. So formed, lock60cfits within cavity58formed in the piston cap section54, and is configured to slide into and out of locking recess36cformed as a channel or race on interior wall38of cylinder32.

In at least one aspect, gasket62is a rubber gasket (e.g., an O-ring). In operation, gasket62forms a seal between the piston body section52and the interior wall38of cylinder32that prevents hydraulic fluid from flowing between the piston body section52and the interior wall38of cylinder32.

Each lock60is configured to move radially within a corresponding cavity58formed within piston head50between a locked position (FIG. 3A) and an unlocked position (FIG. 3B). In the locked position, each lock60engages a corresponding locking recess36a,36b, and prevents the axial movement of piston assembly130between the retracted position and the extended position. In the unlocked position, each lock60disengages from its respective locking recess36such that piston assembly130moves freely from the retracted position to the extended position.

According to the present disclosure, the radial movement of the locks60from the locked position to the unlocked position is responsive to the fluid pressure within chamber34. To accomplish this, one aspect of cylinder32comprises a first conduit66connected to an extension port64and a second conduit68connected to a retraction port69. When the piston assembly130is in the locked position, hydraulic fluid is pumped into cylinder32via extension port64and enters chamber34at or near the piston cap section54. When the fluid pressure within cylinder32and at extension port64, reaches a predetermined amount (i.e., greater than the biasing force of the biasing members61), locks60disengage locking recesses36and move radially towards support section56. At the same time, hydraulic fluid that is already in chamber34is pumped out of cylinder32via retraction port69. Once the locks60are fully disengaged from the locking recesses36, the increasing fluid pressure on piston cap section54moves piston assembly130towards the extended position.

To move the piston assembly from the extended position to the retracted position, the hydraulic fluid that already exists in chamber34is pumped out of cylinder32via the extension port64, while hydraulic fluid is pumped into chamber34via retraction port69. Thus, the pressure of the hydraulic fluid entering chamber34via the retraction port69(i.e., the pressure of the fluid pressing on the piston body section52) increases, while the pressure of the hydraulic fluid exiting chamber34via extension port64(i.e., the pressure of the fluid pressing on the piston cap section54) decreases. The changes in fluid pressure within chamber34move the piston assembly130axially from the extended position to the retracted position. Further, because the hydraulic fluid exerts a decreasing amount of fluid pressure on locks60, the biasing members61radially bias the locks60back into engagement with the locking recesses36.

In addition to the piston head50, actuator30is also configured to include a monolithic castle nut80. As seen in the figures, monolithic castle nut80is configured to threadably engage the interior wall38of cylinder32proximate one end of actuator30and comprises a body82having an interior wall82aand an exterior wall82b, a first channel84formed on the exterior wall82bof the castle nut80, a second channel88formed on the interior wall82aof the castle nut80, first and second gaskets86,90(e.g., O-rings) sized to fit within corresponding first and second channels84,88, respectively, an end gland scraper92, and a scraper assembly94.

As seen inFIGS. 3A-3B, the piston rod70moves axially through a central bore98(best seen inFIGS. 4A-4B) of castle nut80as the piston assembly130moves between the extended and retracted positions. Additionally, gaskets86and90form respective seals to prevent hydraulic fluid from leaking out of chamber34. In particular, gasket86seated in first channel84and is configured to form a seal between an exterior wall82bof castle nut80and the interior wall38of cylinder30, and prevents the leakage of hydraulic fluid between interior wall38and the body82of castle nut80. Gasket90is seated in a second channel88and is configured to form a seal between an interior wall82aof castle nut80and the piston rod70, and prevents the leakage of hydraulic fluid between interior wall82aof the castle nut80and piston rod70. The end gland scraper92is disposed in a channel formed on the interior wall82aof the castle nut80, and functions to scrape the piston rod70as it moves through the central bore98to trap dirt and prevent it from entering chamber34. The scraper assembly94comprises a scraper and a gasket (e.g., another O-ring). The scraper is configured to contact the piston rod70as it moves within the central bore98and functions to scrape the piston rod70as it moves axially through the central bore.

A castle nut80configured according to the present aspects provides benefits that conventional castle nuts do not provide. By way of example only, a castle nut80configured according to the present aspects is a monolithic member manufactured from titanium. Thus, castle nut80comprises fewer component parts than a conventional castle nut. Further, the components parts that are no longer included for castle nut80are manufactured from aluminum and aluminum alloys. By eliminating these components, a castle nut80configured according to the present disclosure is lighter than a conventional castle nut. Moreover, because the castle nut80is monolithic, it is less complex to repair or replace.

FIG. 4Aillustrates a larger view of the end gland scraper92seen inFIGS. 3A-3Bshowing the gaskets86,90, end gland scraper92, and scraper assembly94. As previously described, the first and second channels are sized to receive corresponding first and second gaskets86,90. However, those of ordinary skill in the art should appreciate that these components, while useful, may not be included in some examples of actuator30. For instance, in at least one embodiment, seen inFIG. 4B, the monolithic castle nut80does not include the gaskets86,90, end gland scraper92, and scraper assembly94. By also removing these components, this aspect of the present disclosure may further decrease the costs associated with manufacturing and maintaining such castle nuts80and actuators30, thereby increasing profitability and savings.

FIG. 5is a flow chart illustrating a method100for operating an actuator30according to one aspect of the present disclosure. As seen inFIG. 5, method100begins with moving the piston assembly130within cylinder32between the retracted position and the extended position (box102). As previously described, the movement of the piston assembly130is responsive to the pressure of the hydraulic fluid within the cylinder32. Method100then calls for moving lock60connected to the piston assembly130radially between the locked position, in which the lock60engages a locking recess formed on an interior wall38of cylinder32, and an unlocked position, in which lock60disengages the locking recess36(box104). As stated above, lock60moves radially within a cavity58responsive to the fluid pressure within cylinder32. Method100then calls for biasing lock60into the locked position when the fluid pressure within the cylinder32is less than a predetermined fluid pressure (box106). In one aspect, the biasing member61biases the lock60into the locked position when the predetermined fluid pressure at the extension port is less than the biasing force exerted on lock60by the biasing member61.

FIG. 6is a flow chart illustrating a method110for moving the locking mechanism140of an actuator30according to one aspect of the present disclosure. As seen inFIG. 6, method110calls for supplying cylinder32with hydraulic fluid via extension port64such that when the fluid pressure at extension port64reaches the predetermined fluid pressure (e.g., greater than the biasing force exerted on lock60by biasing member61), lock60moves radially to the unlocked position (box112). To move the locking mechanism140to the locked position, method110calls for supplying cylinder32with hydraulic fluid via retraction port69such that when the fluid pressure at extension port64falls below the predetermined fluid pressure (e.g., is less than the biasing force exerted on lock60by biasing member61), lock60moves radially to the locked position (box114).

FIG. 7is a flow chart illustrating a method120for operating an actuator30with a monolithic castle nut80according to one aspect of the present disclosure. As seen inFIG. 7, method120calls for threadably engaging cylinder32with the monolithic castle nut80proximate one end of an actuator30(box122). In one aspect, castle nut80comprises an end gland scraper92. In these aspects, then, method120calls for scraping piston rod70as it moves through a central bore98formed in the monolithic castle nut80(box124). The end gland scraper92, as described above, removes dirt from piston rod70and traps the dirt thereby preventing it from entering chamber34.

In the present disclosure, methods100,110, and120are illustrated and explained as respective figures. However, those of ordinary skill in the art should readily appreciate that this is for illustrative purposes only. In some aspects, method100illustrated inFIG. 5can further include the steps of methods110and/or120ofFIGS. 6 and 7, respectively.

The foregoing description and the accompanying drawings represent non-limiting examples of the methods and apparatus taught herein. For example, the present disclosure describes an actuator30in the context of an aircraft10. However, those of ordinary skill in the art will readily appreciate that this is for illustrative purposes only, and that the aspects described herein are not limited solely to use in aircraft. Rather, the previously described aspects can be implemented on other types of vehicles to achieve the same or similar benefits. Such vehicles include, but are not limited to, manned and unmanned automobiles, manned and unmanned aircraft, manned and unmanned rotorcraft, manned and unmanned rockets and/or missiles, manned and unmanned surface water borne craft, manned and unmanned sub-surface water borne craft, and the like, as well as combinations thereof. As such, the aspects of the present disclosure are not limited by the foregoing description and accompanying drawings. Instead, the aspects of the present disclosure are limited only by the following claims and their legal equivalents.