Epicyclic Gear Arrangement for Propeller Control
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Solution Overview
Problem
Existing mechanical arrangements for engines with two propeller stages face challenges in locating and controlling additional components, such as pitch control mechanisms and monitoring equipment, due to the complexity of signal and fluid passage through multiple rotating frames of reference, leading to heavy and prone-to-failure slip rings and complex control algorithms.
Innovation Solution
A mechanical arrangement featuring two epicyclic gear stages with a stationary planet carrier and annular sun gear, allowing static structures to be integrated for sensing, control, and monitoring without passing through the rotating frames, using conduits for signal and fluid transport and simplifying the actuation train.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional components (pitch control mechanism, monitoring equipment) are located axially behind the epicyclic gear arrangement, then sensing and control functions can be provided for both propeller stages, but signals and fluids must pass through multiple rotating frames of reference requiring heavy slip rings and muff couplings
Solution Approach 1:
The patent inverts the conventional arrangement by making the planet carrier stationary instead of rotating, and making the annulus rotate to drive the propeller stage. This inversion allows the static structure to be located behind the gear arrangement without requiring signals and fluids to pass through rotating frames of reference, thereby eliminating the need for heavy slip rings and muff couplings while maintaining reliability
2Ease of operation
If additional components are mounted in the rear rotating frame of reference and controlled by components in that frame, then control can be simplified, but control algorithms spanning multiple moving frames of reference become complex
Solution Approach 1:
By inverting the gear arrangement so that the planet carrier is stationary and the annulus rotates, the patent allows control components to be mounted on the stationary structure rather than on rotating frames. This eliminates the need for complex control algorithms that would be required to coordinate components across multiple rotating frames of reference, while still enabling effective control of both propeller stages
3Device complexity
If a single epicyclic gear stage is used to drive two propeller stages, then the structure is simple, but it is not simple to locate additional components axially behind the gear arrangement
Solution Approach 1:
The patent uses a single epicyclic gear stage with an inverted configuration where the planet carrier is stationary and the annulus rotates. This inversion creates a stationary structure behind the gear arrangement, providing mounting space for additional components such as pitch control mechanisms and monitoring equipment, thereby maintaining structural simplicity while enabling component adaptability
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
Enables accurate and reliable control of propeller stages with reduced failure rates and increased flexibility in gear ratios, eliminating the need for complex signal passage and heavy slip rings, while allowing for efficient transport of electrical, hydraulic, and cooling fluids.
Implementation Method 1
a first epicyclic gear stage comprising a sun gear, a planet gear, a planet carrier and an annulus, wherein the sun gear is driven by a shaft of the engine
Data Source
AI summary
A mechanical arrangement for an engine having two propeller stages, including: a first epicyclic gear stage including a sun gear, a planet gear, a planet carrier and an annulus, wherein the sun gear is driven by a shaft of the engine, the planet carrier is stationary and thereby permits static structure to be located there through, and the annulus outputs torque and/or drive; a second epicyclic gear stage including a second sun gear, a second planet gear, a second planet carrier and a second annulus, wherein the second sun gear is driven by the annulus of the first epicyclic gear stage and is annular to accommodate the static structure, the second planet carrier includes the output to one of the propeller stages and the second annulus includes the output to the other of the propeller stages; wherein the static structure provides mounting for static components on one or both sides of each epicyclic gear stage.