Actuator Assembly Drag Brake Emergency Backup
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Solution Overview
Problem
Mechanical linear actuators in aeronautical applications often require separate emergency systems that occupy additional space and hardware, which can be cumbersome and inefficient in case of failures, such as landing gear extension issues.
Innovation Solution
An integrated emergency backup system within the actuator assembly that uses a gas generator to decouple the actuation member from the release member during emergencies, allowing the actuator to move to a predetermined locked position, thereby ensuring safe operation even in failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate emergency systems are provided to override mechanical linear drive systems, then reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent integrates the emergency backup system directly into the actuator assembly, combining the motor-driven ball screw mechanism with a drag brake assembly and spring-loaded release mechanism. This merging eliminates the need for separate emergency systems while maintaining reliability, as the drag brake can independently hold or move the control surface if the motor fails.
Solution Approach 2:
The actuator assembly is designed with multi-functionality, where the same assembly serves both normal motor-driven operation and emergency backup operation. The drag brake assembly can function in multiple modes: holding the control surface stationary, assisting motor operation, or independently moving the control surface if the motor fails, thereby reducing the need for additional dedicated hardware.
2Reliability
If separate emergency systems are provided, then reliability is improved, but the amount of hardware and space required increases
Solution Approach 1:
The emergency backup components (drag brake, spring mechanism, release mechanism) are integrated within the existing actuator housing and structure. This merging allows the emergency system to share space and structural elements with the normal drive system, significantly reducing the quantity of additional hardware and space requirements compared to separate emergency systems.
3Device complexity
If integrated emergency backup system with drag brake is used, then device complexity is reduced, but friction and energy loss increase
Solution Approach 1:
The drag brake assembly is designed with adjustable friction characteristics that can be dynamically modified based on operating conditions. The brake shoes can be positioned to provide different levels of friction engagement, allowing the system to optimize between minimal friction during normal operation and sufficient friction for emergency holding or movement, thereby reducing unnecessary energy loss.
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 integrated emergency backup system automatically decouples the actuator components during failures, ensuring the landing gear can extend fully and lock in place, enhancing safety and reducing the need for additional hardware, allowing for efficient and reliable operation.
Implementation Method 1
The brake shoes and brake disks form a drag brake assembly that slows the rate of movement of the actuation tube
Implementation Method 2
a spring assembly that applies force to a brake shaft
Implementation Method 3
rotation of the ball screw forces the ball nut to extend along the shaft
Data Source
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AI summary
An actuator assembly includes an actuation member, a release member, and a source of pressurized gas, wherein during a normal mode of operation, the actuation member and the release member are engaged to move in unison, and wherein during an emergency mode of operation, pressurized gas automatically decouples the actuation member from the release member to move separately. In accordance with yet other aspects of the disclosure, an electro-mechanical actuator includes an electro-mechanical drive system and an integrated backup system operated by a gas generator, wherein when the backup system is activated, the electro-mechanical drive system is decoupled and the actuator moves to a predetermined position and mechanically locks in place.