Aircraft wing fold actuation system

Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils

Reexamination Certificate

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Reexamination Certificate

active

06260799

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to aircraft actuation systems and, more particularly, to aircraft wing fold actuation systems for folding an outboard wing section relative to an inboard wing section.
BACKGROUND OF THE INVENTION
Many modem day aircraft, especially military aircraft, are equipped with wings having sections that are folded between a spread or deployed position where the aircraft is operational and a folded or stored position that allows the aircraft to be stored in a space efficient manor. Examples of such aircraft include missiles that have folding wing sections to allow storage in a launch canister and carrier based airplanes that must fold their wings for compact storage on and below the carrier deck.
Typically, the mechanisms that fold the wings must securely lock the wings in the deployed position for flying and, in the case of carrier based aircraft, must lock the wing in the stored position so that it does not accidentally deploy to the spread position due to wind and other forces on the carrier deck. The air load on the wing creates large moments on such mechanisms in both the deployed and stored positions. As modem aircraft move towards thinner wing sections, the space available to react the large moments is becoming increasingly restricted.
For carrier based aircraft, one traditional approach for the folding mechanism is to have a series of geared rotary actuators staged one after another in a line along the cord of the wing to form a “piano hinge” arrangement. The geared rotary actuators react all the wing loads and moments through their internal components. This tends to increase both the complexity and weight of the rotary actuators. Often, the systems also include a plurality of latch pins mounted in one of the wing sections that extend into mating bores on the other wing section to lock wing sections together in the deployed position. However, these devices can bind during engagement or disengagement due to the relatively snug fits required to ensure a secure lock of the wing sections in the deployed position. In addition to inhibiting reliable operation, this binding can produce undesirable wear in the devices. Other wing fold systems have been proposed utilizing linkage mechanisms. However, while these systems may be suitable for their intended purpose, there is always room for improvement.
SUMMARY OF THE INVENTION
It is the principal object of the invention to provide a new and improved aircraft wing fold actuation system.
According to one embodiment of the invention, an aircraft wing fold actuation system is provided for folding an outboard wing section relative to an inboard wing section between a deployed position and a stored position. The system includes an actuatormounted on the inboard wing section, and a four-bar linkage connected between the inboard and outboard wing sections to drive the outboard wing section between the deployed and stored positions. The actuator includes a rotary output. The four-bar linkage includes a crank link connected to the rotary output to be rotated thereby about an axis, and a coupler link extended between the crank link and the outboard wing section. The coupler link is pivoted to the crank link and the outboard wing section to transmit a drive force from the crank link to the outboard wing section to drive the outboard wing section between the deployed and stored positions. The crank and coupler links are within 5° of crank link rotation of one of their toggle position with the outboard wing section in the deployed position and within 15° of their other toggle position with the outboard wing section in the stored position.
According to one facet of the invention, the wing fold actuation system includes a crank link pivoted to the inboard wing section at a first pivot point for rotation about an axis between first and second angular positions relative to the inboard wing section, a ground link extending between the inboard and outboard wing sections, a follower link connected to the outboard wing section for movement therewith relative to the inboard wing section between the deployed and stored positions, a coupler link extending between the crank link and the follower link, and a rotary actuator connected to the second link to transmit torque to the second link to pivot the second link between the first and second positions. The ground link is fixed to the inboard wing section to prevent relative movement therebetween. The outboard wing section is pivoted to the ground link at a second pivot point for movement between the deployed and stored positions. The second pivot point is spaced from the first pivot point. The coupler link is pivoted to the follower link at a third pivot point spaced from the second pivot point. The coupler link is pivoted to the crank link at a fourth pivot point spaced from the first and third pivot points. The crank and coupler links are within 5° of crank link rotation of a toggle position with the crank link in the first position and the outboard wing section in the deployed position. The crank and coupler links are within 15° of crank link rotation of another toggle position with the crank link in the second angular position and the outboard wing section in the stored position.
According to another facet of the invention, the system includes a catch fixed to the outboard wing member for movement therewith between the deployed and stored positions, a rotary latch mounted to the inboard wing member for rotation about an axis, and an actuator connected between the outboard wing section and the inboard wing section to drive the outboard wing section between the deployed and stored positions. The catch has a first cam surface, and the rotary latch has a second cam surface that is engaged with the first cam surface with the rotary latch in a first angular position and the outboard wing section in the deployed position to prevent movement of the outboard wing section from the deployed position toward the stored position. The system further includes a timing transmission connected between the actuator and the rotary latch to transmit drive torque from the actuator to rotate the rotary latch about the axis to and from the first angular position. The rotation is timed with the movement of the outboard wing section between the deployed and stored position so that the cam surfaces disengage as the actuator drives the outboard wing section from the deployed position toward the stored position and the cam surfaces engage as the actuator drives the outboard wing section from the stored position to the deployed position.
According to one facet of the invention, the actuator includes a geared rotary actuator having a rotary output, and the transmission includes a gear train connected between the rotary output and the rotary latch to transmit drive torque from the rotary output to the rotary latch.
According to yet another facet of the invention, the gear train includes a first gear connected to the rotary output for rotation therewith and a second gear connected to the rotary latch for rotation therewith about the axis of rotation for the rotary latch. The second gear is meshed with the first gear to be driven thereby.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.


REFERENCES:
patent: 2044357 (1936-06-01), Kerr
patent: 2289224 (1942-07-01), Swanson et al.
patent: 2468425 (1949-04-01), Carpenter et al.
patent: 2538602 (1951-01-01), Taylor et al.
patent: 2665085 (1954-01-01), Crocombe et al.
patent: 4778129 (1988-10-01), Byford

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