Thrust Reverser Lost Motion Linkage for Lower Bypass Drag
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Solution Overview
Problem
Existing thrust reversers in aircraft propulsion systems suffer from increased bypass flowpath drag due to drag links extending across the flowpath when not in use, reducing engine efficiency during normal operation.
Innovation Solution
A thrust reverser assembly with a translating structure and a linkage mount that includes a mount link, mount spring, and mount stop, which limits the pivoting of the blocker door to reduce drag by using a biasing element and stop to control the pivoting motion, and a draglink-less design that minimizes obstruction during non-use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drag links are used to pivot blocker doors, then the thrust reverser can be deployed effectively, but the drag links extend across the bypass flowpath during normal operation increasing drag and reducing engine efficiency
Solution Approach 1:
The drag link is extracted from the bypass flowpath by pivoting it about a pivot axis located on the inner fixed structure. The mount link is positioned such that when the blocker door is in the stowed position, the drag link is rotated away from the bypass flowpath, eliminating the drag penalty during normal engine operation while maintaining the mechanical linkage needed for thrust reverser deployment.
Solution Approach 2:
The drag link transitions from a static position extending across the bypass flowpath to a dynamic configuration that pivots about an axis on the inner fixed structure. This dynamic repositioning allows the linkage to adapt its position based on operational mode - extending into the flowpath when needed for deployment and retracting away when not in use to minimize drag.
2Adaptability or versatility
If the mount link is allowed to pivot freely about the pivot axis, then the linkage can accommodate translating structure movement, but excessive pivoting may occur causing instability or interference
Solution Approach 1:
The mount spring is pre-loaded to apply a biasing force on the mount link before the translating structure moves. This preliminary action ensures that the mount link maintains a predetermined angular position relative to the inner fixed structure, preventing excessive pivoting while still allowing controlled movement to accommodate the translating structure's displacement.
Solution Approach 2:
The mount spring provides continuous feedback force on the mount link, resisting deviations from the predetermined angular position. As the translating structure moves and attempts to pivot the mount link, the spring generates an opposing force that limits the pivoting range and stabilizes the linkage configuration, preventing interference or instability.
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 reduces drag and enhances engine efficiency by minimizing the obstruction of the bypass flowpath when the thrust reverser is not in use, improving overall propulsion system performance.
Implementation Method 1
The mount spring is configured to bias the mount link about the pivot axis against the mount stop
Data Source
AI summary
An assembly is for an aircraft propulsion system. This assembly includes a fixed structure, a translating structure and a thrust reverser. The translating structure is configured to translate between a stowed position and a deployed position. The thrust reverser includes a blocker door, a linkage mount and an actuation linkage. The blocker door is pivotally coupled to the translating structure. The linkage mount includes a mount link, a mount spring and a mount stop. The mount link is pivotally coupled to the fixed structure about a pivot axis. The mount spring is configured to bias the mount link about the pivot axis against the mount stop. The actuation linkage operatively couples the blocker door to the mount link.