Thrust Reverser Blocker Door Delay Mechanism
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Solution Overview
Problem
In turbofan engines with cascade type thrust reversers, the drag link within the airflow and steps/gaps around the blocker door generate drag losses and aerodynamic disturbances, reducing efficiency.
Innovation Solution
A system with a delay mechanism coupled to the blocker door, allowing it to be stowed radially outboard of the fan case and deployed only when clear of the fixed structure, eliminating the need for in-stream drag links and associated fittings, and incorporating a pushrod and latch mechanism to manage the deployment and stowing of the blocker door.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a drag link is used to attach the blocker door to the fixed structure, then the blocker door can be securely positioned, but drag losses and aerodynamic disturbances increase
Solution Approach 1:
The drag link is completely removed from the system. Instead of using a drag link to attach the blocker door to the fixed structure, the patent uses a alternative mechanism where the blocker door is pivotally attached only to the sleeve, and its positioning is achieved through the interaction between the sleeve translation and the door's pivotal movement, eliminating the in-stream drag link that caused aerodynamic losses
Solution Approach 2:
Instead of attaching the blocker door to the fixed structure (traditional approach), the patent inverts the attachment relationship by pivoting the door to the moving sleeve and allowing it to be positioned relative to the fixed structure through the sleeve's translation, thereby moving the attachment point from the fixed structure to the moving component
2Ease of operation
If the blocker door is pivotally attached to the sleeve, then the door can deploy with the sleeve movement, but steps and gaps around the door generate aerodynamic disturbances
Solution Approach 1:
The blocker door is designed as a dynamic component that changes its position and orientation during operation. It is pivotally attached to allow it to rotate from a stowed position (flush with the sleeve) to a deployed position (blocking the bypass duct), enabling smooth transitions that minimize aerodynamic disturbances at all times
Solution Approach 2:
The blocker door is positioned in advance to be flush with the sleeve outer surface during stowed conditions, preventing aerodynamic disturbances before they can occur. The door is prepared in its optimal position (flush alignment) before deployment is required
3Length of moving object
If the sleeve stroke length is increased to fully deploy the blocker door, then the door can clear the fixed structure, but the device complexity increases
Solution Approach 1:
The deployment mechanism is segmented into distinct functional components: the translating sleeve, the pivotally attached blocker door, and the delay mechanism with track and latch. This segmentation allows each component to perform its specific function independently, reducing overall complexity while achieving the required sleeve stroke for full door deployment
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Aspects are directed to a system associated with a thrust reverser of an aircraft, comprising: a blocker door 236 and a fan case, where when the thrust reverser is stowed the blocker door 236 is stowed at least in part radially outboard of the fan case. Aspects include a thrust reverser system comprising: a fixed structure, a translating sleeve 232 configured to translate relative to the fixed structure, at least one blocker door 236 pivotally mounted to the translating sleeve 232, and a rod 256 coupled to the fixed structure and to the at least one blocker door 236, where during a first phase of thrust reverser deployment the blocker door 236 translates with the translating sleeve 232 when the translating sleeve 232 is translating toward its deployed position and does not rotate, and during a second phase following the first phase, the blocker door 236 pivots relative to the translating sleeve 232 from a stowed position to a deployed position.