Propeller Blade Pitch Actuation System Valve Control
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Solution Overview
Problem
Propeller blade pitch actuation systems in aircraft require high hydraulic pressure to move blades through their range, leading to the need for heavy or expensive pumps, pressure actuators, lines, and fittings, which is a weight and cost concern.
Innovation Solution
A propeller blade pitch actuation system that employs a valve to selectively connect the propeller control module drain line to either a drain line with a restriction or a lower-pressure drain line without restriction, increasing hydraulic pressure only when needed, such as during full reverse thrust, to reduce the weight and cost of hydraulic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high hydraulic pressure is used to move propeller blades through their range, then sufficient force is available to adjust blade pitch to full coarse and reverse positions, but heavier or more expensive pumps, pressure actuators, lines, and fittings are required
Solution Approach 1:
The system dynamically switches between two drain line configurations based on operational requirements. During ground operations requiring full reverse thrust, the valve connects the PCM drain line to the unrestricted second drain line to maximize hydraulic pressure. During normal flight operations, the valve connects to the first drain line with a restriction that maintains sufficient pressure while reducing component requirements. This dynamic reconfiguration allows the system to achieve high force only when needed rather than continuously requiring high-pressure components
Solution Approach 2:
The system changes the hydraulic pressure parameter dynamically by switching between two drain line paths. The valve modifies the drain line configuration to either include or exclude the restriction, thereby changing the hydraulic pressure level in the PCM based on operational conditions. This parameter change allows sufficient pressure force to be available when needed while avoiding the continuous weight penalty of high-pressure rated components
2Force
If high hydraulic pressure is used to move propeller blades through their range, then sufficient force is available to adjust blade pitch to full coarse and reverse positions, but more expensive pumps, pressure actuators, lines, and fittings are required
Solution Approach 1:
The system dynamically switches between two drain line configurations based on operational requirements. During ground operations requiring full reverse thrust, the valve connects the PCM drain line to the unrestricted second drain line to maximize hydraulic pressure. During normal flight operations, the valve connects to the first drain line with a restriction that maintains sufficient pressure while reducing component requirements. This dynamic reconfiguration allows the system to achieve high force only when needed rather than continuously requiring high-pressure components
Solution Approach 2:
The system changes the hydraulic pressure parameter dynamically by switching between two drain line paths. The valve modifies the drain line configuration to either include or exclude the restriction, thereby changing the hydraulic pressure level in the PCM based on operational conditions. This parameter change allows sufficient pressure force to be available when needed while avoiding the continuous weight penalty of high-pressure rated components
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
This solution provides sufficient hydraulic pressure to move propeller blades throughout their range without the need for heavier or more expensive components, optimizing weight and cost while ensuring operational functionality, particularly during ground operations where increased pressure is required.
Implementation Method 1
The propeller actuator is a translating piston which moves when a pressure force, in the form of a hydraulic pressure difference, is applied to the piston
Implementation Method 2
Hydraulic pressure of the first drain line between the valve and the drain line restriction is greater than hydraulic pressure of the second drain line
Data Source
AI summary
A propeller blade pitch actuation system (120) includes a propeller control module PCM (24), a PCM drain line (26), a first drain line (140), a drain line restriction (150), a second drain line (42) and a valve (44). The PCM drain line (26) connects to the PCM (24) to drain hydraulic fluid. The first drain line (140) is downstream of the PCM drain line (26), and the drain line restriction (150) is downstream of the first drain line (140). The second drain line (42) is downstream of the PCM drain line. The valve (44) includes a first valve position and a second valve position. The first valve position connects the PCM drain line (26) to the first drain line (140), and the second valve position connects the PCM drain line (26) to the second drain line (42). Hydraulic pressure of the first drain line (140) between the valve (44) and the drain line restriction (150) is greater than hydraulic pressure of the second drain line (42).