US-20260125151-A1 - GEAR DISCONNECT MECHANISM FOR LANDING GEAR ACTUATOR EMERGENCY DEPLOYMENT

US20260125151A1US 20260125151 A1US20260125151 A1US 20260125151A1US-20260125151-A1

Abstract

An aircraft landing gear includes a main beam coupled to the aircraft for reciprocating movement between a stowed position and a deployed position. An actuator is configured to drive the reciprocating movement of the main beam. The actuator includes a ball screw and a motor. The motor has an output shaft operably coupled to the ball screw through a gear train and configured to drive selective rotation of the ball screw. The actuator further includes a disconnect mechanism with a disconnect fitting rotatably mounted to the ball screw. A biasing fitting engages the disconnect fitting to rotate the disconnect fitting between a first position and a second position. The disconnect fitting transfers rotation of the output shaft to the ball screw when the disconnect fitting is in the first position. The ball screw is isolated from the output shaft when the disconnect fitting is in the second position.

Inventors

Rana Kamran Latif

Assignees

WOODWARD, INC.

Dates

Publication Date: 20260507
Application Date: 20251219

Claims (20)

1 . An actuator configured to drive the reciprocating movement of a rotatable object, comprising: a ball screw; a motor having an output shaft operably coupled to the ball screw and configured to drive selective rotation of the ball screw; and a disconnect mechanism, comprising: a disconnect fitting rotatably mounted to the ball screw; and a biasing fitting engaging the disconnect fitting to rotate the disconnect fitting between a first position and a second position, wherein the disconnect fitting transfers rotation of the output shaft to the ball screw when the disconnect fitting is in the first position, and the ball screw is isolated from the output shaft when the disconnect fitting is in the second position.
2 . The actuator of claim 1 , wherein the motor drives rotation of a gear having a splined surface, and the disconnect fitting includes an engagement element disposed on an elongate member, wherein rotation of the disconnect fitting engages and disengages the engagement element from the splined surface.
3 . The actuator of claim 2 , wherein the biasing fitting is configured for sliding translation along a centerline of the ball screw between a connection position and an isolation position, wherein translation of the biasing fitting from the isolation position to the connection position engages the biasing fitting with the first end of the elongate member to rotate the disconnect fitting.
4 . The actuator of claim 3 , wherein engagement of the biasing fitting with the elongate member when the biasing fitting is in the connection position maintains engagement of the engagement element with the splined surface.
5 . The actuator of claim 4 , wherein translation of the biasing fitting from the connection position to the isolation position engages the biasing fitting with the second end of the elongate member to rotate the disconnect fitting.
6 . The actuator of claim 5 , wherein engagement of the biasing fitting with the second end of the elongate member when the biasing fitting is in the isolation position prevents engagement of the engagement element with the splined surface.
7 . The actuator of claim 3 , wherein the biasing fitting has an ovoid shape.
8 . The actuator of claim 3 , wherein the biasing fitting is coupled to a first end of a rod slidingly disposed within the ball screw for translational movement along the centerline of the ball screw.
9 . The actuator of claim 8 , wherein an actuation element is coupled to a second end of the rod, the actuation element being configured to move the biasing fitting from the connection position to the isolation position.
10 . The actuator of claim 9 , wherein the actuation element is a cable.
11 . The actuator of claim 9 , wherein the disconnect mechanism further comprises a biasing element urging the biasing fitting toward the connection position.
12 . The actuator of claim 11 , wherein the disconnect mechanism further comprises a locking feature configured to resist the biasing element to maintain the biasing fitting in the isolated position.
13 . The actuator of claim 12 , wherein the locking feature comprises a locking fitting slidably received within an aperture formed in the rod when the biasing fitting is in the isolated position.
14 . An aircraft landing gear, comprising: a main beam coupled to the aircraft for movement between a stowed position and a deployed position; and an actuator configured to drive the movement of the main beam, the actuator comprising: a ball screw; a motor configured to drive rotation of the ball screw; an arm rotatably connected to the ball screw; and a biasing fitting configured to cause the arm to rotate between a first position and a second position, wherein when in the first position, the arm transfers motion from the motor to the ball screw, and when in the second position, the ball screw is isolated from the motion from the motor.
15 . The aircraft landing gear of claim 14 , wherein the motor drives rotation of a gear having a splined surface, and the arm is connected to an engagement element, wherein rotation of the arm engages and disengages the engagement element from the splined surface.
16 . The aircraft landing gear of claim 15 , wherein the biasing fitting is configured for sliding translation along a centerline of the ball screw between a connection position and an isolation position, wherein translation of the biasing fitting from the isolation position to the connection position engages the biasing fitting to rotate the arm.
17 . The aircraft landing gear of claim 16 , when the biasing fitting is in the connection position, the engagement element is engaged with the splined surface.
18 . The aircraft landing gear of claim 14 , wherein the biasing fitting has an ovoid shape.
19 . The aircraft landing gear of claim 16 , further comprises a biasing element urging the biasing fitting toward the connection position.
20 . The aircraft landing gear of claim 19 , further comprises a locking feature configured to resist the biasing element to maintain the biasing fitting in the isolated position.

Description

RELATED APPLICATIONS This application is a continuation of U.S. Patent Application No. 18/834,570, filed July 30, 2024, which is a 371 national phase of Application No. PCT/US2023/032213 filed September 9, 2023. This application claims priority to each of the above-referenced applications and incorporates herein by reference those applications in their entirety. BACKGROUND An aircraft landing gear assembly is generally movable between a deployed (extended) condition, for take off, landing, and taxiing, and a stowed (retracted) condition for flight. An actuator may be provided for moving the landing gear assembly between the deployed and stowed conditions. This type of actuator is known in the art as a “retraction actuator.” A retraction actuator may have one end coupled to the airframe and another end coupled to the main strut such that extension and retraction of the actuator results in movement of the main strut between deployed and stowed conditions. Landing gear actuators are required to have an emergency deployment mechanism in case of a system failure such as power loss. Under such failure, the landing gear shall be able to deploy under gravitational force. Hydraulic actuators achieve this function by means of hydraulic pressure release, which allows the system to backdrive and deploy the landing gear. However, for electromechanical actuators, the backdriving of the actuator requires larger external force due to inherent system drag. The present disclosure provides embodiments of disconnect mechanisms suitable for use with landing gear assemblies having electromechanical actuators. Disclosed embodiments include a ball screw driven by an electric motor through a gear train. The disconnect mechanisms selectively isolate the gear train output from the ball screw to reduce inherent system drag so that the landing gear can deploy under gravitational forces. SUMMARY Embodiments of landing gear disconnect mechanisms are set forth below according to technologies and methodologies of the present disclosure. The disconnect mechanisms are configured such that in the event of a system failure, the actuator can be put in a disconnected state to reduce inherent system drag so that the landing gear can deploy under the force of gravity. A first representative embodiment of a landing gear system for an aircraft landing gear includes a main beam coupled to the aircraft for reciprocating movement between a stowed position and a deployed position. An actuator is configured to drive the reciprocating movement of the main beam. The actuator includes a ball screw and a motor. The motor has an output shaft operably coupled to the ball screw through the gear train and configured to drive selective rotation of the ball screw. The actuator further includes a disconnect mechanism with a disconnect fitting rotatably mounted to the ball screw. A biasing fitting engages the disconnect fitting to rotate the disconnect fitting between a first position and a second position. The disconnect fitting transfers rotation of the output gear shaft to the ball screw when the disconnect fitting is in the first position. The ball screw is isolated from the output gear shaft when the disconnect fitting is in the second position. In any embodiment, the motor drives rotation of a gear having a splined surface, and the disconnect fitting includes an engagement element disposed on an elongate member, wherein rotation of the disconnect fitting engages and disengages the engagement element from the splined surface. In any embodiment, the elongate member has a first end and a second end, the first end and the second end defining an angle therebetween. In any embodiment, the angle is between 100° and 150°. In any embodiment, the biasing fitting is configured for sliding translation along a centerline of the ball screw between a connection position and an isolation position, wherein translation of the biasing fitting from the isolation position to the connection position engages the biasing fitting with the first end of the elongate member to rotate the disconnect fitting. In any embodiment, engagement of the biasing fitting with the elongate member when the biasing fitting is in the connection position maintains engagement of the engagement element with the splined surface. In any embodiment, translation of the biasing fitting from the connection position to the isolation position engages the biasing fitting with the second end of the elongate member to rotate the disconnect fitting. In any embodiment, engagement of the biasing fitting with the second end of the elongate member when the biasing fitting is in the isolation position prevents engagement of the engagement element with the splined surface. In any embodiment, the biasing fitting has an ovoid shape. In any embodiment, the biasing fitting is coupled to a first end of a rod slidingly disposed within the ball screw for translational movement along the centerline of the ball screw. In any embodim