Thrust Reverser Locking Mechanism for Intermediate Door Position
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Solution Overview
Problem
Existing thrust reverser door actuators in turbojet engines face fatigue due to permanent stress from maintaining intermediate positions during flight, requiring special sizing for reliability and safety, and are vulnerable to breakdowns.
Innovation Solution
A locking system with bolts that secures the doors in an intermediate opening position, using cams and axial guidance to resist lateral forces, and springs to maintain the locked position without actuator effort, ensuring safety and reducing mechanical stress on actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If actuators maintain intermediate position of doors during flight, then door position control is achieved, but actuator fatigue increases due to permanent stress
Solution Approach 1:
The patent extracts the position maintenance function from the actuator by introducing a separate locking mechanism. The lock engages with a cam at the intermediate position, removing the continuous stress burden from the actuator while maintaining precise door position control during flight.
Solution Approach 2:
The locking mechanism acts as an intermediary between the actuator and the door. It receives the positioning command from the actuator, maintains the position independently through mechanical locking, and releases when needed, thereby protecting the actuator from permanent stress.
2Reliability
If actuators maintain intermediate position of doors during flight, then door position control is achieved, but actuator sizing must be increased for fatigue resistance
Solution Approach 1:
The patent extracts the position maintenance function from the actuator by introducing a separate locking mechanism. This allows the actuator to be sized for transient operation only, reducing its complexity and dimensions while maintaining reliable door position control through the added locking system.
Solution Approach 2:
The patent segments the door position control system into two independent functions: transient positioning by the actuator and sustained position maintenance by the locking mechanism. This segmentation allows each component to be optimized independently, reducing actuator sizing complexity.
3Duration of action of moving object
If locks are added to secure intermediate position, then actuator fatigue is reduced, but device complexity increases
Solution Approach 1:
The locking mechanism is designed to be self-actuating through spring force and cam geometry. The spring automatically engages the lock at the intermediate position and maintains it without requiring continuous actuator effort, while the cam profile ensures proper timing and positioning, reducing overall system complexity despite adding locking components.
4Reliability
If locks are designed to resist axial forces without actuator effort, then locking reliability is improved, but mechanism complexity increases
Solution Approach 1:
The spring-loaded locking mechanism uses spring force to counterbalance axial forces acting on the door during flight. The spring is pre-loaded to provide sufficient force to maintain the locked position against aerodynamic loads, ensuring reliable locking without requiring continuous actuator effort.
Solution Approach 2:
The cam profile uses a curved spiral geometry to convert rotational motion into axial locking motion. The curved path of the cam ensures smooth engagement and disengagement of the lock, while the geometry naturally guides the locking force to resist axial loads, improving reliability without complex mechanisms.
Data Source
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AI summary
The invention relates to a system for locking the position of the flaps of a thrust reverser of a turbojet nacelle, said flaps being controlled by actuators, each one swinging about a transverse pivot in order to partially close off the air stream so as to guide it forwards, characterised in that it comprises locks (36) for locking the flaps in an intermediate opening position, between the closed position and the entirely opened-up position.