Wing flap mechanism for high fowler, drooping spoilers and high efficiency

A trailing edge flap mechanism for an aircraft incorporates a flap actuator 28 and a fore flap link 30 that pivots by actuation of the flap actuator. The fore flap link has a hinged end 32 pivotally coupled to a fore flap structure 34 and a clevis end 36 pivotally coupled to a fixed wing structure 18 at a first hinge axle 38. A rocking lever 40 is pivotally coupled to a second hinge axle 42 on the fixed wing structure. A connector bar 44 has a first end 46 pivotally coupled to the fore flap link at a first connection axle 48 and a second end 50 pivotally coupled to the rocking lever at a second connection axle 52. Pivotal movement of the fore flap link causes movement of the connector bar that is translated into rotational movement of the rocking lever about second hinge axle 42 to move an aft flap link 54 pivotally coupled to an aft flap structure 56 at a first pivot axle 58 and pivotally coupled to the rocking lever at a second pivot axle 60, thereby deploying the flap to a lowered position relative to a trailing edge portion of the wing.

This application is copending with application Ser. No. 16/172,748 filed on Oct. 27, 2018 and entitled FLAP SUPPORT MECHANISM-C BAR.

BACKGROUND INFORMATION

Field

Embodiments of the disclosure relate generally to the field of aircraft flap extension systems and, more particularly to a trailing edge flap mechanism employing a pivoting fore flap link engaged to a rocking lever with mechanical advantage to urge an aft flap link downward for increased camber with minimized chord growth.

Background

Aircraft employ flaps which increase camber of the wings for enhanced aerodynamic efficiency in take-off and landing. Various mechanical arrangements have been developed to deploy the flaps from retracted to extended positions. Prior art solutions for large commercial aircraft may have high actuator loads which require complex mechanical arrangements and large actuators or transmission systems which may increase aircraft weight, cost and complexity.

SUMMARY

Exemplary implementations provide a trailing edge flap mechanism for an aircraft incorporating a flap actuator and a fore flap link that pivots by actuation of the flap actuator. The fore flap link has a hinged end pivotally coupled to a fore flap structure and a clevis end pivotally coupled to a fixed wing structure at a first hinge axle. A rocking lever is pivotally coupled to a second hinge axle on the fixed wing structure. A connector bar has a first end pivotally coupled to the fore flap link at a first connection axle and a second end pivotally coupled to the rocking lever at a second connection axle. Pivotal movement of the fore flap link causes movement of the connector bar that is translated into rotational movement of the rocking lever about the second hinge axle to downwardly draw an aft flap link pivotally coupled to an aft flap structure at a first pivot axle and pivotally coupled to the rocking lever at a second pivot axle, thereby deploying the flap to a lowered position relative to a trailing edge portion of the wing.

The implementations disclosed provide a method for deployment of an aircraft flap wherein a fore flap link is engages by a drive screw with rotation provided by an actuator. The fore flap link is rotated about a first hinge axle attached to a fixed wing structure inducing rotation in a rocking lever about a second hinge axle with a connector bar, pivotally attached to the fore flap link at a first connection axle and the rocking lever at a second connection axle. An aft flap link is drawn downward with the rocking lever, with the aft flap link causing a flap, pivotally attached to the aft flap link at an aft flap structure, to be drooped downward.

DETAILED DESCRIPTION

The implementations described herein provide a trailing edge flap mechanism for high fowler and drooping spoiler configuration on an aircraft. A leveraged configuration with a fore flap link driving a rocking lever with one or more connector bars offset from hinge points of the fore flap link and rocking lever for added mechanical advantage reduces actuator loads significantly and maintains strong mechanical advantage throughout the flap travel. Lower actuator loads enable reduced burden on the actuator system thereby reducing weight and cost.

Referring to the drawings,FIGS. 1A, 1B and 1Cdepict an aircraft10having a wing12with operating flaps14. The flaps14are engaged to the wing12at multiple attachment points with underwing structures partially housed within fixed fairings16aand movable fairings16b. Extension of the flaps14to enhance aerodynamic performance during takeoff and landing is accomplished with a trailing edge flap mechanism17causes the flaps14and movable fairings16bto rotate downward relative to the wing12. As seen inFIG. 2, at each attachment point an underwing beam (UWB)18provides fixed wing structure to attach the flaps14and associated operating support links and actuators (to be described in greater detail subsequently) to the wing12. The UWB18is attached to the wing12on a lower surface20formed by a wing lower skin22and partially housed within the fixed fairing16a. A rear spar24extends upward within the wing12from the wing lower skin22and the UWB18is attached to the rear spar with attachment brackets26.

The trailing edge flap mechanism17incorporates a flap actuator28attached to the UWB18. A fore flap link30is operably connected to a drive screw29of the actuator28and pivots by actuation of the flap actuator. A hinged end32of the fore flap link is pivotally coupled at a drive axle33to a fore flap structure34such as a cap spar or forward spar in the flap14. A clevis end36of the fore flap link30is pivotally coupled to the UWB18with a first hinge axle38that is located such that the fore flap link30pivots to move the flap between a retracted position proximate a trailing edge portion13of a wing12and a deployed lowered position. Drive axle33is located at a pivot length31between the first hinge axle38and the drive axle33. A rocking lever40is pivotally coupled to a second hinge axle42on the UWB18. A connector bar44has a first end46pivotally coupled to the fore flap link with a first connection axle48and a second end50pivotally coupled to the rocking lever with a second connection axle52. The first connection axle48is offset from first hinge axle38by a first lever arm39and the second connection axle52is offset from second hinge axle42by a second lever arm43(seen and described with respect toFIG. 3subsequently). As will be described in greater detail with respect toFIGS. 5A-5E, pivotal movement of the fore flap link30about the first hinge axle38urges the drive axle33aft and causes movement of the connector bar44that is translated into rotational movement (represented by arrow45) of the rocking lever40about second hinge axle42. A supporting aft flap link54, pivotally coupled to an aft flap structure56, such as an aft spar of the flap14, at a first pivot axle58and pivotally coupled to the rocking lever40at a second pivot axle60, is drawn downward to urge the flap14to a lowered position relative to the trailing edge portion13of the wing12. The axle dimensions and interconnections shown in the drawings are exaggerated for clarity.

As seen in close upFIG. 3, the coupling of the connector bar44to the fore flap link30between the clevis end36and the hinged end32provides a mechanical advantage with respect to the force applied by the flap actuator28to pivot the fore flap link30. The resulting applied force to the connector bar44due to lever arm39between first hinge axle38and first connection axle48produces rotation of the rocking lever40and associated movement of the aft flap link54deploys the flap14to a lowered position. The length of second lever arm43between second hinge axle42and second connection axle52enhances the rotation of rocking lever40about second hinge axle42. This feature along with rocking length41of the rocking lever40between the second hinge axle42and second pivot axle60draws second pivot axle60and aft flap link54downward more aggressively to provide variable camber of a trailing edge35of the flap14while reducing chord growth of the wing during extension of the flap and with the flap in the extended position. Reduction in chord growth may be particularly applicable for trailing edge variable camber (TEVC) operations. The TEVC will operate by deflecting the trailing edge flaps in 0.5° increments while in cruise and the aggressive droop provided by disclosed trailing edge flap mechanism17herein.

Significant mechanical advantage is provided by the relationship of n rocking length of the rocking lever40, pivot length of the fore flap link30and lever arms of the connector bars44. In exemplary implementations pivot length31and length of lever arm39have a ratio of between 3 and 5, the length of lever arm39and length of second lever arm43have a ratio of between 0.6 and 1.5, rocking length41and the length of second lever arm43have a ratio of between 1.5 and 3, and rocking length41and pivot length31have a ratio of between 0.2 to 0.7.

As seen in the detail view ofFIG. 4for the exemplary implementation, the clevis arrangement of fore flap link30facilitates the use of two connector bars44engaging the first and second connection axles48and52. Rocking lever40also employs a clevis structure at a forward end47for engagement of the second hinge axle42with the UWB18and the second connection axle52. The drive screw29from the actuator28is received through a central aperture62in the fore flap link30and a ball nut64engaging the drive screw29is supported on rotatable pins66extending into the central aperture62. A universal joint68is employed to connect the drive screw29to the actuator28to resolve off-axis motion of the ball nut64during flap extension. The actuator28is mounted to the UWB18with brackets70.

Motion of the trailing edge flap mechanism17is shown inFIGS. 5A-5Efor a range of lowered (drooped) positions of the flap14(10°FIG. 5B, 25°FIG. 5C, 44°FIG. 5Dand 47°FIG. 5E). As the flap14is lowered by rotation of the fore flap link30by drive screw29and ball nut64about first hinge axle38, connector bars44induce rotation of the rocking lever40about second hinge axle42which droops the aft flap link54more aggressively than a mere pivotal attachment of the aft flap link to the UWB18would provide. Additionally, employing the rocking lever40to draw the aft flap link54downward maintains a substantially fixed angular relationship between the fore flap link30and the flap14through the majority of the range of motion (seen inFIG. 3as angle71). The motion of rocking lever40allows a less acute angle (represented inFIG. 3as angle73) to be maintained between the flap14and aft flap link54as represented by an axis74between the drive axle33and first pivot axle58and the centerline76of the aft flap link54between first pivot axle58and second pivot axle60. In exemplary implementations, angle73at 0° flap deflection is 80° and is no less than 70° through half flap deflection (a reduction of the acute angle of only 10°). Angle73remains at least 50° (reduction in the acute angle of less than 30°) at full flap deflection. This feature reacts the load more directly in axial tension along the aft flap link54, reducing unproductive off-axis loads on the fore flap link30. Position of the first hinge axle38at a point on the UWB18and pivot length31of the fore flap link30(seen inFIG. 3) are determined such that pivotal movement of the fore flap link30causes the drive axle33and fore flap structure34to initially move in a first transition portion along a path parallel to a tangent of curvature of the trailing edge portion13of the wing12as seen inFIGS. 5A-5Cas profile72, while the trailing edge of the flap is aggressively drooped by the aft flap link54.

The connector bar44between the fore flap link30and the rocking lever40approaches an ‘over center’ position with first hinge axle38, first connection axle48and second connection axle52substantially aligned (as indicated by line75at a fully deployed position. This allows the loads on the actuator28to remain low when the flap14is fully deployed.

The implementations disclosed herein enable a method600as shown inFIG. 6for deploying flaps for large commercial aircraft. A fore flap link30is engaged by a drive screw29with rotation provided by an actuator28, step602. The fore flap link30is rotated about a first hinge axle38attached to a fixed wing structure (UWB18), step604. A connector bar44, pivotally attached to the fore flap link30at a first connection axle48and a rocking lever40at a second connection axle52, induces rotation in the rocking lever40about a second hinge axle42, step606. The first connection axle48is offset by a lever arm39from the first hinge axle38and the second connection axle52is offset from the second hinge axle42by a lever arm43for mechanical advantage. The rocking lever40draws an aft flap link54downward on a second pivot axle60, step608, with the aft flap link causing a flap14, attached to the aft flap link at an aft flap structure56with a first pivot axle58, to be drooped downward, step610. The length41of the rocking lever40between the second hinge axle42and second pivot axle60is determined to provide rapid droop of the flap14while maintaining an acute angle73greater than 70° between the aft flap link30and the flap14through the majority of the range of motion. A drive axle33, at a hinged end32of the fore flap link30pivotally and connected to a fore flap structure34, urges the flap14aft with rotation of the fore flap link,612. The drive axle33and fore flap structure34initially move in a first transition portion along a profile72parallel to a tangent of curvature of the trailing edge portion13of the wing12, step614. Position of the first hinge axle38at a point on the UWB18and pivot length31of the fore flap link30are determined such that pivotal movement of the fore flap link30moves the drive axle33and fore flap structure34on the profile72.

Having now described various embodiments of the invention in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present invention as defined in the following claims.