Thrust Reverser Closure Initiator for Anti-Jamming Operation
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Solution Overview
Problem
Conventional thrust reversers experience jamming and chattering phenomena due to aerodynamic stresses, especially when actuators fail or deteriorate, leading to the external movable structure becoming stuck in the open position and causing irreversible friction and deformation.
Innovation Solution
Incorporation of a priming element separate from the actuator to exert a transient initiating force during the closing stroke, which realigns and reduces friction, combined with a mechanism to dampen and guide the movable structure, reducing the need for larger actuators and overall mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If actuators are sized to overcome jamming and chattering forces, then the external movable structure can be closed reliably, but the actuator dimensions and mass increase
Solution Approach 1:
A priming element is introduced that acts before the main actuator to initiate the closing stroke. The priming element exerts a preliminary force to start the movement of the external movable structure from the open position, overcoming the initial jamming and chattering forces without requiring the main actuator to be oversized for this purpose.
Solution Approach 2:
The closing force generation is divided into two segments: a priming element that provides the initial force to start closing, and a main actuator that completes the closing stroke. This segmentation allows each component to be optimized for its specific function, reducing the overall mass requirement compared to a single large actuator.
2Object-affected harmful factors
If the external movable structure is allowed to pivot under aerodynamic stresses, then the structure can accommodate flow forces, but friction and deformation increase making closure difficult
Solution Approach 1:
The priming element applies a force in the opposite direction of the aerodynamic-induced tilt before the closing stroke begins. This preliminary anti-action counteracts the tilting moment that causes jamming and chattering, realigning the external movable structure with the guide rails and reducing friction before the main closing action.
3Strength
If guide rail coatings are worn or friction increases, then the structure can withstand operational stresses, but the external movable structure becomes stuck and chattering occurs
Solution Approach 1:
The priming element performs a preliminary action to overcome increased friction forces before the main actuator operates. By applying initial force to start the closing stroke, the priming element ensures that even with worn guide rail coatings, the external movable structure can begin moving without getting stuck or chattering.
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 effectively mitigates jamming and chattering, facilitates easier closure of the external structure, and reduces the dimensions and mass of the thrust reverser components.
Implementation Method 1
These stresses can thus lead to the external moving structure jamming in the open position and a chattering phenomenon during the initiation of the closing stroke
Implementation Method 2
When the external moving structure is in the open position, it is exposed to aerodynamic stresses that can generate a tilting moment tending to cause it to rotate
Data Source
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AI summary
The invention relates to a thrust reverser (12) for an aircraft propulsion unit, this reverser (12) comprising a fixed structure (24) and a mobile external structure (16) able to move between a closed position and an open position so as to cause the reverser (12) to transition respectively between a direct-jet configuration and a reverse-jet configuration. The reverser (12) comprises, on the one hand, one or more actuators configured to move the mobile external structure (16) between the closed position and the open position. The reverser (12) comprises, on the other hand, at least one initiator (23) configured to apply to the mobile external structure (16) a force that initiates a closure travel in which the mobile external structure (16) is moved from the open position towards the closed position.