Dual-Function Braking Device for Electromechanical Actuator Torque Limiting
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Solution Overview
Problem
Existing electromechanical actuators for aircraft flight control surfaces risk damage due to excessive torque when a motor fails, as the overrunning clutch can transmit large forces to the aircraft structure.
Innovation Solution
An electromechanical actuator with a unidirectional transmission member and a brake device that includes an electrical activator, allowing the transmission element to slide relative to the body when excessive torque is applied, thereby limiting the force transmitted and preventing damage, and functioning as both a brake and torque limiter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an overrunning clutch is used to allow free movement in one direction, then the flight control surface can move freely towards one position, but excessive torque can still be transmitted to the transmission system causing damage
Solution Approach 1:
The patent combines the brake device and torque limiter into a single integrated component. The brake device includes an inner ring connected to the transmission element and an outer ring connected to the body, with friction surfaces between them that provide both braking action and torque limiting functionality through controlled sliding
Solution Approach 2:
The patent changes the physical state and interaction parameters by introducing friction-based sliding between the inner and outer rings of the brake device. This sliding mechanism allows the system to transition from rigid torque transmission to controlled slip, limiting the maximum torque to a predetermined safe level while maintaining free movement capability
2Object-affected harmful factors
If a dedicated torque limiter is added to protect against excessive torque, then damage to the transmission system is prevented, but the device complexity increases
Solution Approach 1:
The brake device is designed to perform dual functions: providing braking action to hold the flight control surface in position and limiting torque to prevent damage. This eliminates the need for a separate dedicated torque limiter component, reducing overall device complexity while maintaining protective functionality
Solution Approach 2:
The brake device is designed as a multi-functional component that simultaneously provides braking, torque limiting, and protection against excessive forces. The same friction-based sliding mechanism serves multiple protective and control functions, reducing the total number of components needed in the transmission system
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 effectively limits excessive torque, preventing damage to the transmission system and aircraft structure, while maintaining a compact design without the need for additional torque limiters.
Implementation Method 1
a maximum transmissible torque that is defined by sliding between the inner ring and the outer ring
Data Source
AI summary
An electromechanical actuator comprising a body and an electric motor driving at least one motion transmission element connected to the body via a brake device, and a unidirectional transmission member, the brake device including an electrical activator member so that when the activator member is powered, the unidirectional transmission member is released relative to the body, and when the activator member is not powered, the unidirectional transmission member is secured to the body and opposes pivoting of the transmission element in one direction of rotation up to a maximum transmissible torque defined by the torque limiter.