Aircraft Thrust Reverser Actuator with Alternate Load Path
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Solution Overview
Problem
Existing thrust reverser systems face challenges with oversized and heavy actuator configurations due to high end-of-stroke reverse thrust loads, particularly during rejected take-off, which increase size and weight requirements, and are inefficient during lower in-transit loads.
Innovation Solution
The implementation of a thrust reverser system with a transcowl and an actuator configuration that bypasses end-of-stroke loads by directly transmitting actuator loads through a tension rod to the support structure, reducing the size and weight of the actuator and mounting bracketry, using a screw-type actuator with a nut and tension rod to manage the transcowl's movement between stowed and deployed positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional actuator configuration is used to handle end-of-stroke reverse thrust loads, then the thrust reverser system can achieve the required stopping power, but the actuator size and weight become significantly larger and heavier
Solution Approach 1:
The actuator system is segmented into two distinct load paths: (1) a primary load path through the actuator mechanism for in-transit loads, and (2) an alternate load path through the tension rod and support structure for end-of-stroke loads. This segmentation allows each component to be sized for its specific function, reducing overall actuator weight while maintaining full reverse thrust capacity.
Solution Approach 2:
The tension rod acts as an intermediary element that provides an alternate load path from the rod end to the support structure. This intermediary component bypasses the actuator mechanism during end-of-stroke conditions, allowing the actuator to be smaller while still achieving the required force capacity through the combined load paths.
2Reliability
If an oversized actuator is used to handle peak reverse thrust loads, then the system achieves sufficient stopping power, but the actuator is inefficient and excessively heavy during lower in-transit loads
Solution Approach 1:
The system dynamically switches between two operational modes: (1) actuator-driven movement for in-transit loads with lower force requirements, and (2) tension rod-supported positioning for end-of-stroke loads with peak force requirements. This dynamic load path selection optimizes energy efficiency during the majority of the stroke while maintaining reliability at peak loads.
Solution Approach 2:
The system changes the active load path parameter based on the operational phase: during in-transit movement, loads are borne by the actuator mechanism; at end-of-stroke positions, loads are transferred to the tension rod and support structure. This parameter change allows the actuator to operate efficiently across varying load conditions rather than being continuously oversized.
3Strength
If the actuator directly supports all end-of-stroke loads, then the system achieves required structural support, but the mounting bracketry and actuator size must be significantly larger
Solution Approach 1:
The structural support function is segmented between the actuator mounting bracketry (for in-transit loads) and the tension rod support structure (for end-of-stroke loads). This segmentation allows the mounting bracketry to be lighter since it only needs to handle a portion of the total load, while the tension rod support structure handles the peak end-of-stroke loads.
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
This configuration results in a significantly smaller and lighter actuation system, with the tension rod absorbing impact energy and eliminating wear on stow stops, allowing for reduced actuator weight and potentially eliminating stow stops, thereby enhancing operational efficiency and reducing structural stress.
Implementation Method 1
The screw is rotationally mounted at least partially within the actuator housing, is coupled to receive a drive torque, and is configured, upon receipt of the drive torque, to rotate. The nut has an opening through which the screw extends, and is configured, upon rotation of the screw, to translate between a fully retracted position and a fully extended position
Implementation Method 2
The tension rod is engaged by the nut when the transcowl is in the deployed position and is engaged by the rod end when the transcowl is in the stowed position, whereby actuator loads, in both the deployed and stowed positions, are transmitted through the tension rod to the support structure
Implementation Method 3
allowing for reduced actuator weight and potentially eliminating stow stops, thereby enhancing operational efficiency and reducing structural stress
Data Source
AI summary
A thrust reverser system for a gas turbine engine includes a support structure, a transcowl, and an actuator. The transcowl is mounted on the support structure and is axially translatable between a stowed position and a deployed position. The actuator is coupled to the transcowl and the support structure, and is configured to supply an actuation force to the transcowl to thereby move the transcowl between the stowed and deployed positions. The actuator includes an actuator housing, a screw, a nut, a rod end, and a tension rod. The tension rod is engaged by the nut when the transcowl is in the deployed position and is engaged by the rod end when the transcowl is in the stowed position, whereby actuator loads, in both the deployed and stowed positions, are transmitted through the tension rod to the support structure.