Passive-Locking Actuator for Lightweight Thrust Reverser Retraction
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Solution Overview
Problem
Conventional lockable actuators for thrust reversers in turbojets are bulky, heavy, and require additional dedicated locking mechanisms, which increase weight, size, and complexity, making them inefficient for electrical actuation due to the need for extra components and thermal protection.
Innovation Solution
A compact and lightweight electromechanical actuator with a passive locking device that uses the motor's rotation to change lock states without a dedicated active actuator, incorporating a pinion and internally-toothed ring for reduced forces and a movement conversion mechanism to convert linear motion into rotary motion for the lock, enhancing reliability and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional dedicated locking actuator is added to the movable surface, then the reliability of the locking system is improved, but the weight and size of the equipment increase
Solution Approach 1:
The patent combines the locking function with the existing actuator by integrating a lock mechanism that uses the actuator's own motor and mechanical components (screw, nut, extension tube) to actuate the lock. This merging eliminates the need for a separate dedicated locking actuator, thereby maintaining reliability while reducing weight and size.
Solution Approach 2:
The actuator is designed to perform multiple functions: it provides both the primary actuation function (moving the movable surface) and the locking function (securing the movable surface in deployed or retracted position). The single actuator system universally handles both actuation and locking, eliminating redundant components.
2Reliability
If an additional dedicated locking actuator is added to the movable surface, then the reliability of the locking system is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is integrated into the existing actuator structure, combining the actuation and locking functions into a single system. This reduces device complexity by eliminating the need for separate locking actuators and their associated control systems, while maintaining reliability through the unified design.
3Ease of operation
If retraction overtravel is used to facilitate disengaging the locks, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The actuator is designed to automatically perform the preliminary action of moving the extension tube beyond the retracted position (retraction overtravel) as part of its normal operation cycle. This preliminary action automatically facilitates lock disengagement without requiring separate manual intervention or complex control mechanisms, thereby improving ease of operation while minimizing added complexity.
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 solution results in a more compact, reliable, and lightweight actuator that eliminates the need for additional locking actuators, reducing weight and size while maintaining effective locking functionality, thus facilitating the use of electrical actuators for thrust reversal.
Implementation Method 1
a screw connected thereto and extending along a longitudinal axis, a nut engaged on the screw
Implementation Method 2
The outlet shaft of the motor is provided with a pinion meshing with an internally-toothed ring
Data Source
AI summary
A lockable electromechanical actuator including: a screw extending along a longitudinal axis; a nut engaged on the screw and provided with means for connection to an element that is to be moved; and a passive locking device for locking the element that is to be moved in the retracted position; the passive locking device including a device for actuating a lock that can selectively adopt a first position in which the lock prevents relative turning between the screw and the nut, which would lead to the element that is to be moved being deployed, and a second position in which the nut is free to turn, the lock passing from one of its first and second positions to the other one of its first and second positions when the element that is to be moved is taken beyond its retracted position.