Propeller Pitch Control via Fine Stop Collar and Oil Transfer Bearing
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Solution Overview
Problem
Existing pitch control systems for gas turbine engine propellers lack the necessary precision and fail-safes to prevent propeller pitch from entering dangerous or non-ideal ranges, which can lead to catastrophic failures due to varying ambient conditions and operational states.
Innovation Solution
A propeller pitch control system that includes a fine stop collar with discrete fluid passages and an oil transfer bearing, which changes fluid communication based on ground-based or flight-based modes of operation, limiting pitch angle adjustments through hydraulic fluid management and actuator piston translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing pitch control systems are used, then basic pitch adjustment is achieved, but precision and reliability are insufficient leading to potential catastrophic failures
Solution Approach 1:
The pitch control system is segmented into multiple independent components: a controller that receives mode signals, a pitch actuator that adjusts blade angle, and a pitch limit mechanism that independently enforces safety boundaries. This segmentation allows each component to perform its function with high reliability without requiring the entire system to be overly complex.
Solution Approach 2:
The patent introduces an intermediary pitch limit mechanism that acts as a mediator between the pitch actuator and the propeller blades. This intermediary component receives mode signals and actively limits the pitch angle range, providing an additional layer of safety without requiring complete redesign of the existing actuator system.
2Adaptability or versatility
If pitch range is expanded for versatility, then adaptability to different conditions improves, but risk of entering dangerous pitch ranges increases
Solution Approach 1:
The pitch control system dynamically adjusts the allowable pitch angle range based on the received mode signal. During ground operation, the system permits a wider pitch range for versatility, while during flight operation, it automatically constrains the pitch to a safer, narrower range. This dynamic adaptation allows the system to maintain versatility when needed while preventing harmful conditions.
Solution Approach 2:
The system changes the pitch angle parameter limits based on operational mode. The controller modifies the maximum and minimum pitch angles allowed depending on whether the aircraft is on the ground or in flight, thereby adapting the pitch range parameter to match safety requirements for each operational context.
3Measurement precision
If pitch control accuracy is increased, then performance optimization improves, but system complexity and cost increase
Solution Approach 1:
The pitch control system incorporates feedback mechanisms where the controller continuously monitors the actual pitch angle and compares it against the desired pitch and limit boundaries. Based on this feedback, the controller adjusts the actuator commands to maintain accurate pitch control while staying within safe limits, achieving high precision without requiring overly complex hardware.
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 system ensures precise control of propeller pitch, preventing dangerous pitch ranges and enhancing safety by selectively restricting hydraulic fluid flow based on operational modes, thereby maintaining optimal performance across different conditions.
Implementation Method 1
The OTB defines at least one radial stator hole that is in fluid communication with the first fluid passage during a ground-based mode of operation and in fluid communication with the second fluid passage during a flight-based mode of operation
Implementation Method 2
an actuator piston engaged with a propeller blade crankshaft to vary propeller blade pitch. The annular piston is positioned about the OTB in fluid communication with the primary channel
Data Source
AI summary
Systems and methods are disclosed for controlling the pitch angle of a propeller and rotor assembly that selectively limit the pitch angle according to a selected mode of operation. The system comprises a fine stop collar defining a primary channel, an oil transfer bearing (OTB) extending across the fine stop collar, and an actuator piston engaged with a propeller blade crankshaft to vary propeller blade pitch, wherein the annular piston is positioned about the OTB in fluid communication with the primary channel.