Back-up Featherer Hydraulic Rotating Coupling
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Solution Overview
Problem
Conventional power transfer methods for propeller blade pitch control mechanisms in contra-rotating engines, such as slip rings and rotating hydraulic couplings, face high maintenance burdens and reliability issues due to high operating speeds and complex fluid line routing, making them unsuitable for efficient and reliable feathering in case of power failures.
Innovation Solution
A back-up featherer system with a separate back-up hydraulic actuator and rotating coupling, independent from the primary 'to coarse' line, which includes non-contacting interfaces and separate fluid supply lines to ensure independent operation and reduce common mode failures, allowing for efficient angular displacement of propellers without relying on the primary system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If slip rings are used for power transfer in contra-rotating propeller assemblies, then electrical power can be transferred to rotating components, but the high operating speeds significantly reduce slip ring life and increase maintenance burden
Solution Approach 1:
The patent replaces the electrical slip ring system with a hydraulic power transfer system. A hydraulic motor in the rotating field is driven by hydraulic fluid supplied through a rotating hydraulic coupling from a static hydraulic pump. This substitution eliminates the electrical contact issues of slip rings while providing reliable power transfer to the propeller assembly.
Solution Approach 2:
The patent uses hydraulic fluid transmission to transfer power from the static field to the rotating field. The hydraulic coupling allows fluid to pass from the stationary pump to the rotating motor through a rotating seal interface, providing continuous power transfer without the wear problems of electrical slip rings at high speeds.
2Loss of energy
If the rotating interface diameter of hydraulic coupling is reduced to maintain acceptable PV values and leakage, then sealing requirements become more difficult to satisfy and manufacturing becomes more problematic
Solution Approach 1:
The patent changes the operating parameters of the hydraulic coupling by using a larger diameter rotating interface than previously employed. This is made possible by optimizing the PV product through careful selection of hydraulic fluid and seal materials, allowing the interface to operate at acceptable leakage levels despite the larger size. The design accepts higher PV values within safe limits to simplify manufacturing.
Solution Approach 2:
The patent employs advanced composite materials and specialized seal compounds in the rotating hydraulic coupling to achieve acceptable leakage rates with a larger diameter interface. These materials provide the necessary wear resistance and sealing properties that enable the larger interface design to meet performance requirements.
3Reliability
If a separate back-up hydraulic actuator with independent fluid supply lines is implemented, then reliability during power failures is improved, but device complexity increases
Solution Approach 1:
The patent merges the back-up feathering function with the primary hydraulic actuator system by using a common hydraulic motor and coupling infrastructure. The back-up actuator shares the rotating hydraulic coupling and motor with the primary system, reducing the number of separate components. The independence is achieved through separate fluid supply lines and control valves rather than completely separate mechanical systems.
Solution Approach 2:
The hydraulic motor and rotating coupling serve dual functions: they power both the primary pitch control actuator and the back-up feathering actuator. This multi-functionality reduces overall system complexity while maintaining reliability, as the same rotating interface supports multiple hydraulic actuators with independent fluid supplies.
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 back-up featherer system provides a high-integrity, independent feathering mechanism with reduced leakage and increased reliability, capable of tolerating high PV values and maintaining propeller control during power failures, thus stabilizing rotor speed and drag without compromising engine stiffness or introducing additional failure modes.
Implementation Method 1
a back-up hydraulic rotating coupling, the back-up fluid supply lines fluidly communicating with the back-up hydraulic actuator via the back-up rotating coupling; wherein a static side of the back-up hydraulic rotating coupling is mounted to the static structure of the engine arrangement, and a rotating side of the back-up hydraulic rotating coupling rotates with the propeller assembly
Data Source
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AI summary
A back-up featherer is provided for an engine arrangement having a main hydraulic actuator which angularly displaces propellers of a propeller assembly of the engine arrangement. The back-up featherer has a back-up hydraulic actuator for angular displacement of the propellers, the back-up hydraulic actuator rotating with the propeller assembly. The back-up featherer further has one or more back-up fluid supply lines for transferring hydraulic fluid between a hydraulic pressure power source located on a static structure of the engine arrangement and the back-up hydraulic actuator. The back-up featherer further has a back-up hydraulic rotating coupling, the back-up fluid supply lines fluidly communicating with the back-up hydraulic actuator via the back-up rotating coupling. A static side of the back-up hydraulic rotating coupling is mounted to the static structure of the engine arrangement, and a rotating side of the back-up hydraulic rotating coupling rotates with the propeller assembly.