Turbojet Thrust Reverser Drive Mechanism for Delayed Door Deployment
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Solution Overview
Problem
Existing turbofan engine thrust reverser deployment mechanisms do not effectively delay the opening of blocking doors relative to the movement of the movable cowl, which can impact performance during landing.
Innovation Solution
A drive mechanism that coordinates the passage of the movable cowl and blocking door, utilizing a slider, guide means, roller slide, and connecting rod to defer the opening of the blocking door until the movable cowl has passed an intermediate position, ensuring optimal deployment timing and minimizing parasitic drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional deployment mechanism is used, then the blocking door opens simultaneously with the movable cowl deployment, but this causes reduced engine performance during landing due to premature door opening
Solution Approach 1:
The movable cowl is deployed in advance to an intermediate position before the blocking door opens. The drive mechanism allows the cowl to move first, creating a partial opening, and only after this preliminary action is complete does the blocking door begin to open. This sequence ensures optimal timing for thrust reverser activation during landing.
Solution Approach 2:
The deployment process is divided into two distinct phases: first the movable cowl deploys to an intermediate position, then the blocking door opens. This segmentation of the deployment sequence allows independent control of each component's timing, enabling the cowl to prepare the airflow path before the blocking door redirects the thrust.
2Reliability
If the blocking door opens early, then the thrust reverser activates sooner, but this increases parasitic drag during the deployment process
Solution Approach 1:
The movable cowl performs a preliminary deployment action to an intermediate position before the blocking door opens. This preliminary action prepares the nacelle opening and airflow path in advance, allowing the blocking door to open later with minimal disruption to airflow, thereby reducing parasitic drag during the transition.
3Device complexity
If a simple deployment mechanism is used, then the structure is simpler, but it cannot coordinate the delayed opening of the blocking door with the movable cowl movement
Solution Approach 1:
The drive mechanism merges the control of two separate components (movable cowl and blocking door) into a single integrated system. The mechanism combines the cowl translation drive with the door opening drive, using shared elements like the translating cowl that pulls the connecting rod, which in turn opens the blocking door. This unified approach coordinates both movements through one control system.
Solution Approach 2:
A connecting rod acts as an intermediary element between the movable cowl and the blocking door. As the cowl translates, it pulls the connecting rod, which then transfers this motion to open the blocking door. This intermediary component enables coordinated control while maintaining the delayed opening sequence, as the connecting rod only transmits force after the cowl has moved to the intermediate position.
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
This mechanism ensures delayed and coordinated opening of the blocking door with respect to the movable cowl's deployment, enhancing thrust reverser efficiency and reducing drag during deployment and retraction.
Implementation Method 1
a roller slide (15) integral with the frame (6b), the roller slide (15) comprising a rail (16) extending in the direction of translation and a roller (17) movable in rotation in the rail (16)
Implementation Method 2
a connecting rod (18) of which a first end (18a) is movably mounted on the center of the roller (17) and of which a second end (18b) is movably mounted on the blocking door (11)
Data Source
Figure 1
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AI summary
The invention relates to a turbojet engine comprising a nacelle (6) with a fixed cowling (6a), a fan duct (8), and a thrust reverser (9) comprising a movable cowling (12) between a stowed position and a deployed position in which the movable cowling (12) is away from the fixed cowling (6a), at least one locking door (11) movable between a closed position and a fixed position in which said door at least partially blocks the fan duct (8), as well as a drive mechanism (10) for moving the movable cowling (12) and at least one locking door (11), the drive mechanism (10) comprising a roller slide (15), said slide comprising a rail (16) and a roller (17) movable for rotation in the rail (16), a connecting rod (18) having a first end (18a) movably mounted on the roller (17) and a second end (18b) movably mounted on at least one blocking door (11),the rail (16) comprising a bearing surface (50) extending along the direction of translation and parallel to the longitudinal axis (X) to support the connecting rod (18) during the movement of the movable hood (12) from the secured position to an intermediate position of the movable hood (12), said intermediate position being between the secured position and the deployed position of the movable hood (12).