Thrust Reverser Grid Rail Collision Avoidance
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Solution Overview
Problem
In aircraft propulsion assemblies with thrust reversers and mobile grids, the existing methods for transitioning between direct jet and reverse jet configurations can cause collisions between grid rails and the movable cowl during maintenance operations, leading to potential damage.
Innovation Solution
A thrust reverser design featuring removable fixing means that allow the grid rails to be disconnected from the engine, enabling their translation without collision, and a connecting rod system to manage mechanical forces, along with a method for disassembly and reassembly that positions the grid rails to avoid collisions during extraction and reinsertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the grid rails are arranged radially between the internal wall and external wall of the mobile cowl to ensure good absorption of mechanical forces, then the mechanical force absorption is improved, but the grid rails collide with the mobile cowl during engine extraction causing damage
Solution Approach 1:
The grid rails are segmented into multiple sections along their length, allowing different portions to move independently during extraction. This segmentation enables the rails to navigate around the mobile cowl without collision while maintaining structural integrity for force absorption.
Solution Approach 2:
The grid rails are designed with dynamic positioning capability, allowing them to change their radial position relative to the mobile cowl during engine extraction. The rails can move from an initial radial position that provides force absorption to an extracted position that avoids collision with the cowl.
2Ease of repair
If the movable cowl is made hinged to allow maintenance operations, then the ease of maintenance is improved, but the grid rails collide with the open half-hoods during engine extraction
Solution Approach 1:
The grid rails are pre-positioned in an advanced location before engine extraction begins. This preliminary positioning ensures that when the half-hoods are opened for maintenance, the rails are already in a position that prevents collision with the open hoods during subsequent extraction operations.
Solution Approach 2:
A control mechanism acts as an intermediary between the engine extraction system and the grid rails, coordinating the movement of the rails with the position of the half-hoods. This intermediary control ensures that rails are positioned safely relative to the hoods during maintenance operations.
3Stability of the object's composition
If the grid rails are fixed to the motor by embedding to prevent relative movement, then the structural stability is improved, but the engine cannot be extracted without damaging the rails due to collision with the cowl
Solution Approach 1:
The connection between grid rails and motor is segmented into multiple attachment points, allowing the rails to be detached from specific sections during extraction while maintaining stability in other sections. This selective detachment enables extraction without damage.
Solution Approach 2:
The fixation system transitions from a static embedded connection to a dynamic adjustable connection during extraction. The rails can be temporarily detached or repositioned relative to the motor, allowing extraction operations while maintaining structural stability during normal operation.
4Ease of repair
If removable fixing means are used to connect grid rails to the motor, then the ease of maintenance is improved, but additional complexity is introduced to the connection system
Solution Approach 1:
The fixing means are designed as separate, removable components that can be easily extracted from the connection system. This extraction of the fastening function into independent elements simplifies maintenance operations while the modular nature actually reduces overall system complexity.
Solution Approach 2:
The removable fixing means are designed for easy removal and reuse during maintenance cycles. The fastening components can be quickly discarded from the extraction process and recovered for reuse, simplifying the maintenance procedure without requiring complex permanent attachment systems.
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
Facilitates safe and efficient maintenance operations by preventing collisions between grid rails and the movable cowl, allowing for the removal and reinstallation of the engine without damage, while ensuring correct positioning of the grid rails during reassembly.
Implementation Method 1
The half-cowls (41) are respectively connected to the beam rails (421) along a sliding connection allowing translation of the half-cowls (41), relative to the beams (42)
Implementation Method 2
The beams (42) are arranged to be connected by their respective hinges (422) to a reactor mast (2) of the propulsion assembly following a pivot connection
Implementation Method 3
The deflection grids (43) are connected to the rails of the grids (44, 45) according to a slide connection allowing a translation of the deflection grids (43)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an aircraft propulsion assembly with an engine provided with a cascade-type thrust reverser with cascades of mobile deflection vanes (43). The cascades of deflection vanes (43) are connected to cascade rails (45) with a slideway connection that allows the cascades of vanes (43) a translational movement between a cruising-flight position and a reverse-thrust position. The thrust reverser is designed to allow the cascade rails (45) to be positioned in a forward position, in which the engine, the cascade rails (45) and the deflection vanes (43) can be removed from the propulsion assembly without the cascade rails (45) colliding with the mobile cowl (41) of the reverser. The invention also relates to dismantling and assembly or reassembly methods that allow maintenance operations to be carried out on the engine thus dismantled.