Aircraft Monitor Retraction Circuit for Power-Failure Stowage
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Solution Overview
Problem
Existing pivoting display devices for aircraft face reliability issues due to the heavy load on motors and mechanical deterioration when using spring mechanisms for stowing monitors in case of power failures, and they require complex clutch systems and constant load management.
Innovation Solution
A pivoting display device equipped with a forward/reverse rotatable motor, transmission mechanism, electromagnetic brake, and a power unit with a retraction power retention circuit that stores energy in capacitors, allowing the monitor to be stowed securely during power failures without mechanical stress, using a controller to manage the pivoting and power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring mechanism is used to stow the monitor during power failure, then the monitor can be stowed automatically, but the motor load increases and the mechanism becomes more complex
Solution Approach 1:
The patent extracts the stowage function from the motor-driven mechanism by introducing a separate spring mechanism that operates independently during power failure. The spring mechanism is specifically designed to stow the monitor only when power is unavailable, while the motor handles normal operation. This separation reduces the motor's load and simplifies the overall control logic.
Solution Approach 2:
The spring mechanism is pre-loaded during normal operation when the monitor is stowed, storing potential energy in advance. This preliminary action ensures that when power failure occurs, the stored energy is immediately available to drive the monitor back to the stowed position without requiring additional power or complex real-time decision-making.
2Reliability
If a spring mechanism is used to stow the monitor, then automatic stowage is achieved, but mechanical deterioration occurs over time
Solution Approach 1:
The patent replaces the traditional always-engaged mechanical spring mechanism with an intelligent hybrid system. The microcontroller monitors power status and selectively activates the spring mechanism only during power failure, reducing continuous mechanical stress. The motor-driven mechanism with electromagnetic brake handles normal operation, distributing wear more evenly across components.
Solution Approach 2:
The system dynamically adjusts its operation mode based on power availability. During normal operation, the motor-driven mechanism with electromagnetic braking provides controlled movement and holding. During power failure, the spring mechanism provides automatic stowage. This dynamic switching optimizes component usage and reduces cumulative mechanical deterioration.
3Force
If the motor carries heavy load to operate the spring mechanism, then stowage force is sufficient, but motor capacity requirements increase
Solution Approach 1:
The patent extracts the heavy stowage force requirement from the motor by introducing a dedicated spring mechanism. The spring provides the necessary stowage force independently, while the motor only needs to provide enough force to overcome friction and initiate movement. The electromagnetic brake provides holding force, further reducing the motor's continuous load requirements.
Solution Approach 2:
The system uses asymmetric force provision: the spring mechanism provides high force only in the stowage direction during power failure, while the motor provides controlled bidirectional movement during normal operation. The electromagnetic brake provides unidirectional holding force. This asymmetric arrangement allows each component to be optimized for its specific function, reducing overall power requirements.
4Reliability
If a clutch is added to disconnect the motor from the spring mechanism, then operational reliability improves, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical clutch with an electronic control system. The microcontroller monitors power status and selectively activates the spring mechanism, providing the necessary disconnection function without mechanical complexity. The electromagnetic brake provides additional disengagement capability during normal operation, eliminating the need for a dedicated mechanical clutch while maintaining operational reliability.
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
The solution reduces the motor's load, enhances operational reliability, and efficiently charges and discharges capacitors, ensuring secure stowing and maintaining the monitor's open state without mechanical aging, meeting FAA safety requirements.
Implementation Method 1
an electromagnetic brake that is activated at each position in the stowed state and the opened state of the monitor and maintains these states
Implementation Method 2
a retraction power retention circuit that stores the stepped-up DC voltage in the capacitor while the source voltage is supplied and that supplies the power stored in the capacitor to the voltage regulator when there is no source voltage available
Implementation Method 3
a step-up circuit that steps up the transformed DC voltage
Data Source
AI summary
A pivoting device especially useful in aircraft passenger cabins that can pivot a monitor between stowed and open positions, the pivoting device including a forward/reverse rotatable driving motor. An electromagnetic brake holds the monitor in stowed and opened positions A power unit powers the motor and the electromagnetic brake. A controller controls the pivoting movement of the monitor. The power unit includes a rectifier circuit that transforms AC to a DC, a step-up circuit that steps up the transformed voltage, a voltage regulator that adjusts the transformed voltage to a prescribed DC voltage, and a retraction power retention circuit including a capacitor. When no source voltage is detected while the monitor is in its opened state, the capacitor supplies the power to a voltage regulator of the power circuit, deactivates the electromagnetic brake and reverse rotates the motor to drive the monitor to its stowed position.