Dual Epicyclic Gearbox Layout for Turboprop Speed Reduction
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Solution Overview
Problem
Current reduction gearboxes in turboprop engines are inefficient in reducing the high rotational speed of turbines to match the propeller's operational speed, leading to suboptimal performance and increased complexity.
Innovation Solution
The use of a dual epicyclic gearbox system where each engine is connected to a sun gear, carrier, and ring gear configuration, allowing for efficient speed reduction with fewer moving parts and reduced weight, while limiting rotation of specific gears to achieve the desired speed ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional reduction gearbox is used to reduce turbine rotational speed to propeller operational speed, then speed reduction is achieved, but the gearbox complexity and number of moving parts increases
Solution Approach 1:
The reduction gearbox is divided into two separate epicyclic gearbox units, each handling a portion of the speed reduction task. Each unit contains a sun gear, planet gears, and a ring gear, allowing the overall reduction ratio to be achieved through distributed gear stages rather than a single complex assembly
Solution Approach 2:
The patent connects the turbine to the sun gear input and the propeller to the ring gear output, inverting the traditional planetary gear configuration where the carrier is typically the output. This inversion allows for a more compact design with fewer moving parts while achieving the required speed reduction
2Speed
If a conventional reduction gearbox is used, then speed reduction is achieved, but the weight of the gearbox increases
Solution Approach 1:
Multiple gear functions are combined into a single epicyclic unit where the sun gear, planet gears, and ring gear work together to achieve both speed reduction and torque multiplication in one compact assembly, eliminating the need for separate gear trains and reducing overall weight
Solution Approach 2:
The planet gears are nested within the annular space between the sun gear and ring gear, creating a compact concentric arrangement that maximizes gear engagement area while minimizing the overall footprint and weight of the reduction gearbox
3Speed
If a conventional reduction gearbox is used, then speed reduction is achieved, but the number of moving parts and oil requirements increases
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate gears and supporting structures from the reduction mechanism, retaining only the essential sun gear, planet gears, and ring gear components needed to achieve the speed reduction, thereby reducing the quantity of lubricating oil required
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 reduces the number of moving parts, decreases oil requirements, and simplifies the gearbox design, leading to a more efficient and cost-effective speed reduction mechanism, enhancing the overall performance and reliability of turboprop engines.
Implementation Method 1
each of the first and second epicyclic gearboxes has gears carried by a carrier, and a ring gear meshed with the gears
Data Source
AI summary
An aircraft includes first and second engines, one or more aircraft rotors associated with the first and second engines, a first epicyclic gearbox having: a) an output operatively connected at least one of the one or more aircraft rotors, and b) an input defined by a sun gear of the first epicyclic gearbox; and a second epicyclic gearbox having: a) an output operatively connected to at least one of the one or more aircraft rotors, and b) an input defined by a sun gear of the second epicyclic gearbox. Output of the first epicyclic gearbox is defined by the carrier. Output of the second epicyclic gearbox is defined by its ring gear. A multi-engine aircraft and a method of operating a multi-engine aircraft are also described.