Torque Split Gearbox for Coaxial Rotors
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Solution Overview
Problem
Rotary wing aircraft with complex rotor systems face challenges in gearbox design due to the need for large and heavy gearboxes that efficiently transfer power to multiple counter-rotating rotor assemblies and additional thrust systems, leading to increased complexity and weight.
Innovation Solution
A gearbox assembly with two gear sets and a torque split gear reduction stage that transfers power to dual, counter-rotating coaxial main rotor assemblies, utilizing an input bevel shaft and intermediate gear sets to split torque equally between two output pinions, reducing the size and weight of the gearbox components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single large final reduction stage is used to transfer power to dual counter-rotating rotor assemblies, then the gearbox can handle the required torque, but the gearbox becomes large and heavy
Solution Approach 1:
The patent divides the single large final reduction stage into two separate final reduction stages, each serving one rotor assembly. This segmentation allows the gearbox to handle the required torque for dual counter-rotating rotors while using two smaller, more manageable reduction stages instead of one oversized stage, thereby reducing overall gearbox weight and size.
Solution Approach 2:
The patent introduces a new dimensional approach by adding a second final reduction stage along the same power transmission path, effectively creating a multi-stage serial reduction system. This allows torque to be progressively reduced through multiple smaller steps rather than one large step, enabling compact design while maintaining torque capability.
2Adaptability or versatility
If a gearbox is designed to transfer power to dual counter-rotating rotor assemblies and a propeller assembly, then all power requirements are met, but the gearbox complexity increases
Solution Approach 1:
The patent segments the power distribution function into distinct modules: one path for the dual counter-rotating rotor assemblies and another path for the propeller assembly. This modular segmentation allows the gearbox to handle multiple power requirements while keeping each power transmission path relatively simple and manageable.
Solution Approach 2:
The gearbox design incorporates universal components that can serve multiple functions. The two final reduction stages can potentially serve both rotor assemblies and the propeller assembly depending on configuration, allowing a single gearbox unit to handle multiple power distribution requirements without proportionally increasing complexity.
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 solution allows for a more compact and lightweight gearbox design that efficiently transfers power to dual counter-rotating rotor assemblies, reducing the overall weight and envelope of the gearbox while maintaining effective torque distribution and thrust capabilities.
Implementation Method 1
A bevel gear set receives the first torque from the input shaft and transfers the first torque to two intermediate shafts
Implementation Method 2
Each gear set includes a first intermediate idler operably connected to the input bevel shaft, the first intermediate idler and a first output gear disposed at a first intermediate shaft, wherein the first intermediate idler is meshed with a transfer gear disposed at the input bevel shaft
Implementation Method 3
a second output pinion to transfer the second torque acting in the second direction to the second rotor
Data Source
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AI summary
A gearbox system for a dual coaxial counter rotating rotor assembly includes an input shaft to input a first torque into the gearbox system and a transfer shaft operably connected to the input shaft to transfer the first torque therethrough. Two gear sets are operably connected to the transfer shaft. Each gear set includes a first output gear to transfer a second torque acting in a first direction to a first rotor of a rotor assembly and a second output gear to transfer the second torque acting in a second direction opposite the first direction to a second rotor of the rotor assembly. The second torque transferred by each gear set of the two gear sets is substantially equal.