Aircraft Thrust Reverser Cowl Overtravel Braking Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thrust reversers for aircraft propulsion units face issues with the dislocation of the mobile external structure due to aerodynamic forces when the actuator controlling it fails, leading to increased weight and cost due to the need for axial stops to prevent overtravel.
Innovation Solution
Incorporating first and second braking elements that cooperate with each other through sliding friction to generate a braking force that opposes the movement of the mobile external structure beyond the open position, reducing the risk of dislocation and eliminating the need for conventional axial stops, thereby simplifying assembly and reducing weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional axial stop is used to prevent cowl dislocation, then the cowl is retained in position, but the structure must be oversized to absorb collision kinetic energy, increasing mass and cost
Solution Approach 1:
The patent applies beforehand cushioning by introducing a braking mechanism that dissipates kinetic energy through friction during normal operation. The braking elements create progressive resistance that dampens the cowl's movement before it can accumulate enough kinetic energy to cause damage upon collision with the stop, thereby protecting the structure without requiring oversizing.
Solution Approach 2:
The patent changes the parameter of energy dissipation from impact-based (sudden collision with stop) to friction-based (progressive braking). The braking elements transform the cowl's kinetic energy into thermal energy through controlled friction, changing how the system handles the cowl's motion and eliminating the need for an oversized stop structure.
2Reliability
If a conventional axial stop is used to prevent cowl dislocation, then the cowl is retained in position, but the structure complexity and cost increase
Solution Approach 1:
The patent merges the braking function with the existing guide rails and cowls structure. The braking elements are integrated into the longitudinal profiles of the guide rails and cowls, combining the guiding and braking functions into a single integrated system rather than adding separate complex retention mechanisms.
Solution Approach 2:
The guide rails and cowls serve multiple functions: they guide the cowl's movement during normal operation and simultaneously provide braking action through their longitudinal profiles. This multi-functionality eliminates the need for dedicated complex retention structures, simplifying the overall device.
3Device complexity
If the cowl is allowed to move freely beyond the open position, then the structure can be simplified, but the cowl may dislocate due to aerodynamic forces
Solution Approach 1:
The patent applies preliminary anti-action by having the braking elements act against the cowl's movement in the direction of potential dislocation. The longitudinal profiles of the guide rails and cowls create friction-based resistance that opposes and prevents the cowl from moving beyond its intended range, countering the aerodynamic forces before dislocation can occur.
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 dampens the mobile external structure's overtravel, absorbs kinetic energy, and preserves structural integrity while avoiding oversizing, thus enhancing the reliability and efficiency of the thrust reverser.
Implementation Method 1
the first and the second braking element cooperating with each other by sliding with friction when the mobile external structure is moved in the positive sense beyond the open position so as to generate a braking force that opposes this movement
Implementation Method 2
the invention also allows to improve the absorption of the kinetic energy of the mobile external structure during the interruption of its travel beyond the open position
Data Source
AI summary
A thrust reverser for an aircraft propulsion unit, of the type having a mobile cowl able to move between a closed position that allows the propulsion unit to generate thrust and an open position that allows the propulsion unit to generate a reverse-thrust for slowing the aircraft. The reverser includes braking elements such as a slot and a peg respectively integral with a fixed part of the reverser and with the mobile cowl. These braking elements are configured to cooperate with one another by sliding, with friction, when the mobile cowl effects an overtravel, beyond the open position, so as to generate a braking force that opposes this movement. In one preferred embodiment, the slot for this purpose includes a restriction in section along the direction of travel of the mobile cowl.