Propeller Speed Control With Oil Leakage Compensation
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Solution Overview
Problem
Electronic and hydro-mechanical propeller control systems fail to account for oil leakage in propeller shafts, leading to steady-state errors in propeller speed across various operational conditions of aircraft engines.
Innovation Solution
A method and system that calculate and compensate for leakage flow rate by using engine and propeller parameters, including temperature, pressure, and geometric data, to adjust the oil flow request and reduce steady-state errors, utilizing a laminar flow model and biasing mechanisms for fine-tuning during specific engine modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic or hydro-mechanical propeller control systems are used to modulate oil flow to the propeller, then propeller speed control is achieved, but steady-state errors in propeller speed occur due to unaccounted oil leakage in the propeller shaft
Solution Approach 1:
The system continuously monitors actual propeller speed and compares it with the requested speed, using this feedback to calculate and adjust the oil flow request. The leakage compensation component is updated based on the difference between requested and actual speeds, creating a closed-loop control system that eliminates steady-state errors.
Solution Approach 2:
The system dynamically adjusts the oil flow request parameter based on changing operating conditions. By calculating leakage flow rate as a function of engine and propeller parameters (such as speed, temperature, and pressure), the system adapts to varying conditions and maintains accurate propeller speed control throughout the operational envelope.
2Device complexity
If oil flow is metered to the propeller through a servo-valve without leakage compensation, then the control system operates simply, but steady state errors accumulate throughout the operational envelope
Solution Approach 1:
The system pre-calculates the leakage compensation component as a function of engine and propeller parameters before applying it to the oil flow request. By determining the leakage flow rate in advance based on known parameters, the system prepares the necessary compensation without adding complex real-time measurement devices.
Solution Approach 2:
The leakage compensation component acts as an intermediary between the basic oil flow request and the final compensated oil flow request. This intermediate calculation layer allows the system to correct for leakage effects without fundamentally changing the existing control architecture or adding complex hardware.
3Reliability
If leakage compensation is calculated as a function of multiple engine and propeller parameters, then steady state errors are reduced, but calculation complexity increases
Solution Approach 1:
The system replaces complex physical leakage compensation mechanisms with computational models. By using mathematical functions to calculate leakage flow rate based on operating parameters, the system achieves accurate compensation through software algorithms rather than complex mechanical or hydraulic compensation devices.
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 effectively reduces steady-state errors in propeller speed by accurately accounting for leakage, ensuring precise control and stability across the operational envelope of aircraft engines.
Implementation Method 1
determining the leakage flow rate as a function of parameters of the engine comprises estimating the leakage flow rate from a laminar flow model
Data Source
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AI summary
There is described herein methods and system for correcting steady state errors in propeller speed by calculating a leakage flow rate as a function of engine and propeller parameters.