Movable Cowl Speed Control for Thrust Reverser Impact
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Solution Overview
Problem
Movable cowls in thrust reversers for turbojets, actuated by hydraulic or pneumatic systems, are prone to maintenance issues and potential damage due to leaks, and the locks required for safety are oversized to withstand impacts, increasing weight and maintenance challenges.
Innovation Solution
A method that limits the initial opening speed of the movable cowl to a predetermined limit speed, using an electric motor actuation system, with a governing step to prevent high-impact damage on sensitive components, and includes conditional application based on turbojet operating speed and emergency situations, along with a control loop for motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If hydraulic or pneumatic systems are used to actuate movable cowls, then the opening action can be performed with sufficient force, but the system becomes complex, bulky, and requires considerable maintenance due to potential leaks
Solution Approach 1:
The patent replaces hydraulic or pneumatic actuation systems with an electric motor-driven system. The electric motor directly drives the movable cowl through a reduction gear mechanism, eliminating the need for complex hydraulic/pneumatic networks, reducing maintenance requirements, and removing leak-related concerns while still providing sufficient opening force.
Solution Approach 2:
The patent extracts and removes the hydraulic or pneumatic fluid conveyance network from the reverser assembly. By using direct electric motor drive, the complex fluid distribution system, reservoirs, and associated components are completely eliminated, simplifying the overall structure and reducing the bulky installation space required in the front frame.
2Reliability
If locks are dimensioned to withstand high-impact forces, then safety is improved, but the weight of the locks increases
Solution Approach 1:
The patent applies preliminary action by controlling the opening speed of the movable cowl through a governing step before the cowl reaches the position where it would impact the locks. The speed is limited to a predetermined value during the initial phase of opening, preventing high-impact forces from reaching the locks and eliminating the need to oversize them for impact protection.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a speed-governing mechanism that preemptively limits the kinetic energy of the movable cowl before it can strike the locks. This speed limitation acts as a cushioning effect, absorbing the potential impact energy through controlled, slow movement during the critical initial phase of opening.
3Productivity
If the movable cowl opens at high speed, then the operation is faster and more efficient, but the impact power on sensitive components increases causing potential damage
Solution Approach 1:
The patent applies dynamics by making the opening speed of the movable cowl variable rather than constant. The system dynamically adjusts the opening speed based on the position of the cowl: during the initial phase (governing step), the speed is limited to a predetermined value to protect the locks, while after passing the locks, the speed can increase to optimize opening efficiency. This dynamic speed control resolves the contradiction between speed and impact protection.
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
Reduces the risk of damage to sensitive components by limiting initial impact power, allowing for lighter and more reliable electromechanical actuators, enhancing safety and reducing maintenance needs.
Implementation Method 1
the movable cowl is actuated by an electric motor
Data Source
AI summary
The invention concerns a method for opening a mobile cowl (2) actuated by a motor (7) and equipping a turbojet thrust reverser, characterized in that it comprises, at the start of the opening phase, a bridling step (103) whereby the speed of the mobile cowl is maintained lower or equal to a predetermined threshold speed.