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.
1 . An actuator for a flight control member, the actuator comprising:
a cylinder having a longitudinal axis;
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, the piston assembly comprising:
a monolithic piston head comprising:
a solid piston body;
a piston cap that is spaced apart from, and opposite of, the piston body;
a support centrally positioned axially between the piston body and the piston cap;
a plurality of cavities formed between the piston cap and the piston body; and
a seal disposed between the piston body and the interior wall of the cylinder and configured to prevent fluid from flowing between the piston body and the interior wall of the cylinder; and
a piston rod connected to the piston head such that the piston body, the piston cap, and the support are offset from one another and extend along the longitudinal axis of the cylinder; and
a locking mechanism connected to the piston assembly, the locking mechanism comprising:
a plurality of locks, each lock configured to move radially within one of the plurality of cavities 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 plurality of biasing members, wherein each biasing member is disposed within a corresponding cavity between the support and a corresponding lock of the plurality of locks, and is configured to radially bias the corresponding lock into the locked position when the fluid pressure within the cylinder is less than a predetermined fluid pressure.
2 . The actuator of claim 1 further comprising:
an extension port through which fluid enters the cylinder to move the plurality of 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.
3 . The actuator of claim 2 :
wherein each of the plurality of locks move radially to the unlocked position when the fluid pressure at the extension port is not less than the predetermined fluid pressure; and
wherein each of the plurality of locks is biased radially to the locked position when the fluid pressure at the extension port is less than the predetermined fluid pressure.
4 . The actuator of claim 1 further comprising a castle nut engaged with the cylinder proximate one end of the actuator, and comprising a central bore configured to receive the piston rod therethrough.
5 . The actuator of claim 4 wherein the castle nut is a monolithic member and further comprises a scraper assembly comprising a scraper configured to contact the piston rod as the piston rod moves within the central bore.
6 . The actuator of claim 5 wherein the castle nut further comprises one or more channels formed thereon, with each channel sized to receive a corresponding gasket.
7 . The actuator of claim 6 wherein the castle nut further comprises:
a first gasket seated in a first channel and configured to form a seal between an exterior wall of the castle nut and an interior wall of the cylinder; and
a second gasket seated in a second channel and configured to form a seal between an interior wall of the castle nut and the piston rod.
8 . The actuator of claim 1 further comprising:
a first connecting member configured to fixedly attach the actuator to a support structure of an aircraft; and
a second connecting member fixedly attached to the piston rod and configured to attach to a flight control member of the aircraft.
9 . The actuator of claim 8 wherein the first and second connecting members are disposed at opposite ends of the actuator.
10 . The actuator of claim 1 wherein the support extends longitudinally between the piston cap and the solid piston body, and wherein a terminal end of each biasing member is attached to the support.
11 . The actuator of claim 1 wherein the piston assembly is configured to move a flight control member of an aircraft when the piston assembly moves between the retracted position and the extended position.
12 . A method of operating an actuator for a flight control member, the method comprising:
providing a piston assembly within a cylinder of the actuator, the piston assembly comprising:
a monolithic piston head comprising:
a solid piston body;
a piston cap that is spaced apart from, and opposite of, the piston body;
a support centrally positioned axially between the piston body and the piston cap; and
a plurality of cavities formed between the piston cap and the piston body; and
a seal disposed between the piston body and an interior wall of the cylinder and configured to prevent fluid from flowing between the piston body and the interior wall of the cylinder; and
a piston rod connected to the piston head such that the piston body, the piston cap, and the support are offset from one another and extend along a longitudinal axis of the cylinder; and
moving the piston assembly within the cylinder of the actuator between a retracted position and an extended position responsive to fluid pressure within the cylinder;
moving each of a plurality of locks connected to the piston assembly radially within a corresponding cavity between a locked position in which each lock engages a corresponding locking recess formed on an interior wall of the cylinder, and an unlocked position in which each lock disengages the corresponding locking recess, responsive to the fluid pressure within the cylinder;
providing a plurality of biasing members within the piston head, wherein each biasing member is disposed within a corresponding cavity formed in an interior of the piston head between the support and a corresponding lock of the plurality of locks; and
radially biasing each of the plurality of locks within the corresponding cavity into the locked position when the fluid pressure within the cylinder is less than a predetermined fluid pressure.
13 . The method of claim 12 wherein radially moving the plurality of 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 plurality of locks move radially to the unlocked position.
14 . The method of claim 12 wherein the plurality of locks move radially within the corresponding cavity formed in the interior of the piston head between the locked position and the unlocked position.
15 . The method of claim 14 wherein each of the plurality of locks are radially biased within the corresponding cavity towards the corresponding locking recess formed on the interior wall of the cylinder.
16 . The method of claim 14 further comprising engaging the cylinder with a monolithic castle nut proximate one end of the actuator.
17 . The method of claim 16 further comprising 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.
18 . A vehicle comprising:
one or more actuators, each actuator comprising:
a cylinder having a longitudinal axis;
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, the piston assembly comprising:
a monolithic piston head comprising:
a solid piston body;
a piston cap that is spaced apart from, and opposite of, the piston body;
a support centrally positioned axially between the solid piston body and the piston cap;
a plurality of cavities formed between the piston cap and the solid piston body; and
a seal disposed between the piston body and the interior wall of the cylinder and configured to prevent fluid from flowing between the piston body and the interior wall of the cylinder;
a piston rod connected to the piston head such that the piston body, the piston cap, and the support extend along the longitudinal axis of the cylinder; and
a locking mechanism connected to the piston assembly, the locking mechanism comprising:
a plurality of locks, each lock configured to move radially within one of the plurality of cavities 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 plurality of biasing members, wherein each biasing member is disposed within a corresponding cavity between the support and a corresponding lock of the plurality of locks, and is configured to radially bias the corresponding lock into the locked position when the fluid pressure within the cylinder is less than a predetermined fluid pressure.
19 . The vehicle of claim 18 wherein each actuator further comprises:
an extension port through which fluid enters the cylinder to move the plurality of 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.
20 . The vehicle of claim 18 wherein the vehicle is an aircraft, and wherein at least one of the one or more actuators is disposed on a flight control member of the aircraft.