Magnetic Torque Limiter for Aircraft Actuator Safety
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Solution Overview
Problem
Existing electromagnetic actuators for aircraft flight control surfaces risk damage due to excessive torque when a motor failure causes the flight control surface to pivot towards its deployed position, leading to potential damage to the transmission system and aircraft structure.
Innovation Solution
An electromagnetic actuator with a magnetic torque limiter and a brake device, where the magnetic torque limiter is used to limit excessive torque transmission, and the brake device is activated to prevent damage by securing the unidirectional transmission member to the body, allowing the transmission element to slide when excessive torque is applied, thus preventing damage to the aircraft structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a freewheel is used to allow free movement of the flight control surface in one direction, then the flight control surface can move freely towards its deployed position in case of motor failure, but excessive torque can be transmitted to the body and transmission system causing damage
Solution Approach 1:
A magnetic torque limiter is introduced as an intermediary component between the freewheel and the body. This magnetic torque limiter acts as a mediator that allows normal operation while limiting excessive torque transmission. The magnetic torque limiter comprises a magnetic coupling mechanism that transmits torque under normal conditions but slips when torque exceeds a predetermined threshold, thereby protecting the body and transmission system from damage while maintaining the freedom of movement provided by the freewheel.
Solution Approach 2:
The magnetic torque limiter changes the torque transmission parameter dynamically. Under normal operating conditions, it transmits torque efficiently. When excessive torque is detected (beyond the predetermined threshold), the magnetic coupling strength changes, allowing the transmission element to slide relative to the body, thereby limiting the torque transmitted to the body and transmission system.
2Object-affected harmful factors
If a magnetic torque limiter is introduced to limit excessive torque, then damage to the body and transmission system is prevented, but the device complexity increases
Solution Approach 1:
The magnetic torque limiter replaces complex mechanical torque limiting mechanisms (such as friction-based clutches or mechanical overrunning clutches) with a magnetic coupling system. This substitution simplifies the overall device complexity by eliminating the need for complex mechanical components while achieving the same torque limiting function through magnetic fields, which can be controlled more precisely and with fewer moving parts.
3Object-affected harmful factors
If the brake device is activated to secure the unidirectional transmission member, then damage is prevented, but the transmission element cannot slide to relieve excessive torque
Solution Approach 1:
The system employs dynamic control of the brake device activation. The brake device is not continuously activated but is controlled to activate only when excessive torque is detected. This dynamic activation allows the transmission element to slide and relieve excessive torque when needed, while preventing damage during normal operation. The magnetic torque limiter works in conjunction with the brake device to provide this dynamic response, activating the brake only when the magnetic coupling begins to slip.
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 magnetic torque limiter effectively limits torque transmission, preventing damage to the aircraft structure by allowing the transmission element to slide relative to the body when excessive torque is exerted, ensuring the safety and integrity of the actuator system.
Implementation Method 1
The actuator includes a magnetic torque limiter and the brake device comprises 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 magnetic torque limiter.
Implementation Method 2
In the event of excessive torque, the torque limiter allows the transmission element to slide relative to the body, thereby limiting any risk of damaging the body. The use of a magnetic torque limiter is particularly advantageous since there is no friction and the characteristics of the limiter vary little with temperature
Data Source
AI summary
An electromagnetic actuator having a body and an electric motor driving at least one motion transmission element connected to the body via a brake device, a magnetic torque limiter, 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. 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 magnetic torque limiter.