Duplex Rotary EMA Gearbox Architecture for Jam-Tolerant Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electromechanical actuators (EMAs) are prone to jamming, making them unsuitable for safety-critical applications in aircraft, such as primary flight control surfaces, due to the risk of faulty operation.
Innovation Solution
A jam-tolerant, duplex EMA architecture is developed, featuring a common stage gearbox with a sun gear and intermediate gears, and an outer gear structure that allows output control even in the event of partial jamming, utilizing brake assemblies to manage failed actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If EMAs are used to replace hydraulic actuators, then weight and cleanliness are improved, but reliability deteriorates due to jamming
Solution Approach 1:
The EMA system is divided into two independent EMA parts (first and second), each with its own motor and brake assembly. This segmentation allows one part to fail without completely disabling the system, as the other part can still provide control authority through the common output mechanism.
Solution Approach 2:
The patent merges two independent EMA parts into a single coordinated system with a common output mechanism. The first and second EMA parts both connect to the common output through the outer gear structure, allowing them to work together normally but also allowing one to take over if the other fails, thus improving reliability while maintaining weight benefits.
2Productivity
If EMAs are used for primary flight control surfaces, then efficiency is improved, but safety deteriorates due to jamming risk
Solution Approach 1:
Brake assemblies are provided for both the first and second EMA parts to prevent unwanted movement or jamming effects. The brakes can be activated to stop the shafts from rotating if jamming is detected, preventing the harmful effect of uncontrolled movement on flight control surfaces.
Solution Approach 2:
The system monitors the operational status of both EMA parts and can detect jamming conditions through speed and torque variations. This feedback mechanism allows the system to identify when one EMA part has jammed and switch control to the other part, maintaining safety while preserving efficiency.
3Reliability
If a duplex EMA architecture is implemented, then jam tolerance is improved, but device complexity increases
Solution Approach 1:
The common output mechanism serves multiple functions: it transmits power from either the first or second EMA part, allows for coordinated operation of both parts, and provides a unified interface to the flight control surface. This multi-functionality reduces the need for separate output mechanisms for each EMA part, thereby limiting the increase in complexity.
Solution Approach 2:
The outer gear structure acts as an intermediary mechanism that couples both EMA parts to the common output. This intermediary allows the two independent EMA parts to work together or independently without requiring complex direct coupling, simplifying the overall architecture while maintaining jam tolerance.
Data Source
AI summary
A rotary electromechanical actuator (EMA) includes: a first EMA part comprising a first electric motor and a first rotary shaft (S1) extending along an axis and arranged to be rotated about the axis by the first electric motor, and a first 1st stage gearbox providing a geared transmission from the first electric motor to the first output shaft, and a first brake assembly for applying a braking force to the first output shaft; the EMA further comprising: a second EMA part comprising a second electric motor and a second rotary shaft (S2) extending along the axis and arranged to be rotated about the axis by the second electric motor, and a second 1st stage gearbox providing a geared transmission from the second electric motor to the second output shaft, and a second brake assembly for applying a braking force to the second output shaft.