Hydraulic Actuation Control Module for Propeller Pitch Change
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Solution Overview
Problem
Existing hydraulic actuation systems for propeller pitch control are complex, unreliable, and heavy due to the need for multiple subsystems and components interfacing with the engine, with variable drain pressure affecting metering valve accuracy and air content in lubrication oil impacting performance.
Innovation Solution
A hydraulic actuation control module with a flow metering valve and electronic control unit integrated into the propeller assembly, receiving hydraulic fluid supply via a single static line, and including a high pressure pump and auxiliary pump for pressurization, simplifying the interface with the engine and reducing weight by eliminating the need for multiple hydraulic lines and complex systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple subsystems and components are installed on the engine gearbox to transfer hydraulic power from static to rotating parts, then the pitch change actuation can be achieved, but the system complexity, weight, and maintenance requirements increase significantly
Solution Approach 1:
The invention extracts the flow metering valve from the static engine gearbox system and relocates it to the rotating propeller assembly. This extraction eliminates the need for complex high-pressure hydraulic lines and multiple pumps, reducing system complexity while maintaining pitch change actuation functionality. The valve is now integrated into the rotating assembly and receives low-pressure hydraulic fluid through a single static line.
Solution Approach 2:
The hydraulic system is segmented into two independent parts: a static low-pressure hydraulic supply system remaining on the engine, and a rotating high-pressure actuation system on the propeller. This segmentation allows each part to be optimized independently, reducing overall system complexity while maintaining reliability.
2Reliability
If multiple high pressure pumps and control modules are installed on the engine gearbox, then redundant hydraulic power supply is achieved, but the weight and maintenance burden increase
Solution Approach 1:
The rotating propeller assembly serves itself by generating the required high hydraulic pressure locally through the flow metering valve, eliminating the need for heavy high-pressure pumps on the propeller. The system uses the engine's existing low-pressure hydraulic supply and converts it to high pressure at the point of use through the metering valve's restricted orifice design.
3Ease of manufacture
If variable drain pressure from the engine lubrication system is used, then the existing hydraulic infrastructure is utilized, but the metering valve accuracy is affected
Solution Approach 1:
The flow metering valve includes a compensating mechanism that preliminarily adjusts for drain pressure variations. The valve design incorporates a spring-loaded piston that compensates for changes in drain pressure, maintaining consistent flow metering accuracy despite variations in the engine lubrication system's drain pressure.
4Ease of manufacture
If air content in the lubrication oil is not addressed, then the existing oil supply system is used, but the hydraulic actuation performance is degraded
Solution Approach 1:
The invention converts the potentially harmful effect of air content in the oil into a beneficial feature by designing the flow metering valve with a vented cavity that allows air bubbles to escape. The vented cavity design enables the system to tolerate air-contaminated lubrication oil without degrading hydraulic actuation performance, effectively converting the harm of air presence into a manageable condition.
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 configuration simplifies the propeller assembly's construction and maintenance, reduces weight, and improves reliability by integrating the flow metering valve and electronic control unit within the propeller assembly, ensuring consistent hydraulic pressure and reducing the impact of air content in the lubrication oil.
Implementation Method 1
hydraulic fluid pressure is applied from a chamber on each side of a piston, and the pressure differential between the two chambers moves the piston one way or the other
Implementation Method 2
including a high pressure pump and auxiliary pump for pressurization
Data Source
AI summary
An hydraulic actuation control module is provided for installation in a pitch change actuator of a propeller assembly. The module comprises a flow metering valve arranged to supply hydraulic fluid flow and pressure to an actuator and an electronic control unit arranged to control the flow metering valve. The flow metering valve is arranged to meter hydraulic fluid flow and pressure to increase and decrease pitch chambers of the pitch change actuator, in accordance with the control of the electronic control unit. The flow metering valve is arranged to receive an hydraulic fluid supply from an entity relative to which the propeller assembly rotates such as an engine driving the propeller assembly or aircraft on which the propeller assembly is installed. A propeller assembly comprising the hydraulic actuation control module is also disclosed, together with a method of installing the module within a propeller assembly.