Thrust Reverser Cowl Actuator Control via Relative Position Sensing
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Solution Overview
Problem
The control of thrust reverser cowls in turbojet engines is hindered by the reliability issues of hydraulic and pneumatic systems, particularly due to the difficulty in detecting leaks and the complexity of maintaining these systems within the limited space of the aircraft's front frame, and the dependency on absolute position sensors which can lead to unavailability in case of sensor failures.
Innovation Solution
A method for controlling the cowl actuator using an electric motor with a relative position sensor, where the motor control is slaved to the instantaneous position of the cowl, determined by a combination of absolute and relative position data, allowing for reduced dependence on absolute sensors and improved operation even after interruptions, such as power cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic or pneumatic systems are used to actuate the cowls, then the actuation capability is sufficient, but the system complexity and maintenance difficulty increase significantly
Solution Approach 1:
The patent replaces hydraulic or pneumatic actuation systems with an electromechanical actuator consisting of an electric motor and reduction gear. This substitution eliminates the need for hydraulic fluid or compressed air systems, thereby reducing system complexity and maintenance requirements while maintaining sufficient actuation capability for moving the cowls between retracted and extended positions
Solution Approach 2:
The patent extracts and removes the hydraulic or pneumatic fluid transport network from the thrust reverser system. By eliminating this complex network of pipes, pumps, and pressure regulation equipment, the system achieves reduced complexity and improved reliability, as the electromechanical actuator can be self-contained within the limited space of the front frame
2Measurement precision
If absolute position sensors are used to control the cowl position, then the position control precision is improved, but the system availability decreases due to sensor failure risk
Solution Approach 1:
The patent implements a preliminary action by automatically repositioning the cowl to a predetermined safe position (fully retracted or partially extended) upon detection of an interruption during actuation. This preliminary safety measure ensures that even if the absolute position sensor fails or the system experiences a power interruption, the cowl will be in a known safe state, thereby maintaining system availability and safety without requiring continuous reliance on absolute position sensors
Solution Approach 2:
The patent provides beforehand cushioning by implementing redundant control capabilities that do not depend on absolute position sensors. The control system is designed to function using alternative methods (such as relative position sensing or predetermined positioning sequences) when absolute sensors fail, thereby cushioning against the loss of sensor data and maintaining system operation
3Ease of operation
If the space in the front frame is utilized for hydraulic circuit installation, then the actuation function is achieved, but the installation difficulty and protection complexity increase
Solution Approach 1:
The patent replaces the hydraulic circuit with an electromechanical actuator that can be more compactly integrated into the front frame. The electric motor and reduction gear can be housed within a single actuator assembly, eliminating the need for separate hydraulic reservoirs, pumps, valves, and extensive piping, thereby simplifying both installation and protection within the limited space
Data Source
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AI summary
The invention relates to a method for controlling at least one actuator for actuating the cowlings of a thrust inverter in a turbojet engine, the actuator being driven by an electric motor including a relative position sensor providing information on the evolution of the movement thereof, wherein the motor control is carried out based on the instantaneous position of the cowling in at least one portion of the travel thereof between an open position and a closed position, the instantaneous position of the cowling being determined from at least one reference position absolute data and relative position data relative to said reference position provided by the relative position sensor of the motor, wherein in case the actuation is resumed after an interruption, a new determination of the reference position is initiated.