Primary Flight Surface Actuator Using Harmonic Drive Gearing
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Solution Overview
Problem
Electromechanical actuators (EMAs) are not currently used for primary flight control surfaces in aircraft due to unresolved issues with ball screw and motor blockage, limiting their application in safe flight control and energy efficiency benefits.
Innovation Solution
A compact, high-torque, low-backlash electromechanical actuator using a harmonic drive gear coupled with a lightweight, high-power electric motor, specifically designed for primary flight control surfaces, reducing weight and installation space while ensuring high performance and mechanical stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ball screw and motor mechanisms are used in electromechanical actuators for primary flight control surfaces, then the actuator can provide the necessary actuating motion, but the risk of blockage increases and reliability decreases
Solution Approach 1:
The patent extracts and eliminates the ball screw mechanism from the actuator design, replacing it with a direct-drive motor configuration. This removal of the problematic ball screw component directly addresses the blockage risk while maintaining the necessary actuating motion through alternative mechanical means, thereby improving reliability without excessive complexity
Solution Approach 2:
The patent introduces a cam mechanism as an intermediary component between the motor and the flight control surface. This cam mechanism translates rotational motor motion into the required linear or angular actuating motion without using a ball screw, providing a reliable intermediate transmission stage that avoids blockage while maintaining control precision
2Loss of energy
If electromechanical actuators replace hydraulic systems in primary flight control surfaces, then energy efficiency improves and fuel consumption decreases, but the risk of motor and drive mechanism blockage increases
Solution Approach 1:
The patent removes the ball screw mechanism that is prone to blockage, retaining only the essential motor and cam components. This extraction eliminates the primary source of reliability issues while preserving the energy efficiency benefits of the electromechanical system, as the direct-drive configuration reduces energy losses compared to hydraulic systems
Solution Approach 2:
The patent changes the mechanical parameters of the drive system by using a cam mechanism with optimized geometry that provides smooth motion transmission without the high contact pressures and friction associated with ball screws. This parameter change reduces the likelihood of blockage while maintaining the energy efficiency of the electromechanical actuator
3Ease of repair
If EMAs are used for primary flight control surfaces, then maintenance requirements decrease and survival probability increases, but the blockage problem of ball screws and motors remains unresolved
Solution Approach 1:
The patent extracts the ball screw mechanism that requires complex maintenance and is prone to blockage, replacing it with a simpler cam-based system. This extraction significantly reduces maintenance requirements while eliminating the blockage problem, as the cam mechanism has fewer moving parts and no recirculating elements that can fail
Solution Approach 2:
The patent employs a cam mechanism that can be designed as a simple, replaceable component with a predetermined service life. This approach allows for easy replacement rather than complex repair, reducing maintenance requirements and improving reliability by ensuring that worn components are systematically replaced before failure occurs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The actuator provides significant weight savings, improved energy efficiency, and increased reliability, enabling precise and durable control of primary flight surfaces, including thrust vector control in VTOL aircraft, with reduced maintenance and energy consumption.
Implementation Method 1
an electromechanical actuator using a harmonic drive gear coupled with a lightweight, high-power electric motor
Data Source
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AI summary
The present disclosure relates to an actuator (1) for generating an actuating movement for a primary flight control surface (2). This actuator (1) comprises an electric motor (5) and a reduction gear coupled thereto. This reduction gear is formed as a harmonic drive gear (strain wave gear) (6). The disclosure also relates to a civil aircraft equipped with such an actuator (1). In this aircraft, the actuator (1) according to the disclosure can be used in particular as a flap actuator for adjusting a flap structure (2) pivotally hinged to a trailing end of a wing structure (3).