Propeller Overspeed Threshold Control Without Thrust Dissymmetry
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Solution Overview
Problem
Existing aircraft propeller overspeed protection systems often cause in-flight thrust dissymmetry between healthy and failed propellers by varying blade angle, which can lead to control hazard failures.
Innovation Solution
Adjusting the propeller speed threshold dynamically based on target propeller speed to rapidly detect overspeed and reduce propeller speed without varying blade angle, thereby avoiding thrust dissymmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If blade angle is varied to control propeller pitch in response to overspeed, then propeller speed is controlled, but thrust dissymmetry occurs between healthy and failed propellers
Solution Approach 1:
The patent changes the parameter being controlled from blade angle to propeller torque. Instead of varying blade angle to control propeller speed, the system adjusts torque parameters to achieve speed control, thereby avoiding the thrust dissymmetry problem that arises from blade angle variation on failed propellers
Solution Approach 2:
The patent extracts the blade angle control function from the overspeed protection process. By removing blade angle variation from the overspeed response, the system eliminates the source of thrust dissymmetry while maintaining speed control through alternative means (torque control)
2Device complexity
If fixed propeller speed threshold is used, then overspeed detection is simple, but detection accuracy varies across different flight phases
Solution Approach 1:
The patent implements a dynamic threshold adjustment mechanism where the propeller speed threshold is no longer fixed but adapts based on flight phase and target propeller speed. This dynamic approach maintains detection accuracy across varying operational conditions while preserving system simplicity through automated adjustment
Data Source
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AI summary
A method of operating a propeller system for an aircraft, the propeller system comprising a propeller, the method comprising: receiving propeller speed information, the propeller speed information indicating propeller speed; receiving a target propeller speed; performing a propeller speed threshold adjustment process, the propeller speed threshold adjustment process comprising adjusting a propeller speed threshold as a function of the target propeller speed; comparing the propeller speed to the propeller speed threshold; and in response to propeller speed exceeding the propeller speed threshold, performing an overspeed protection process.