Multi-path Torque Split Gearbox for Rotary Wing Aircraft
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Solution Overview
Problem
Conventional split-torque gearbox systems for aircraft are heavy, voluminous, and require unequal load sharing, leading to oversized gears and limited adaptability across different aircraft platforms, with a need for a system that is simpler, lighter, and more adaptable.
Innovation Solution
A multi-path torque split gearbox system with three-stage power gear train modules, featuring a spiral bevel gear mesh in the first stage, spur gear mesh in the second stage, and double helical gear mesh in the third stage, allowing for independent redundant load paths and adaptable engine mounting locations through torsionally flexible quill shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional split-torque gearbox systems are used, then torque can be distributed through multiple paths, but the system becomes heavy and voluminous
Solution Approach 1:
The gearbox is divided into multiple independent drive train paths (first, second, and third paths) that can operate separately or in combination. Each path contains its own gear stages and can transmit torque independently, allowing the system to segment the torque distribution function across multiple lighter sub-systems rather than requiring one heavy integrated system.
Solution Approach 2:
The gearbox design provides multi-functionality by enabling torque to be transmitted through multiple possible paths depending on operational requirements. The same physical components serve multiple functions: the first and second drive train paths can operate together for normal torque distribution, or either can operate independently for redundancy, making the system adaptable to various power transmission needs without requiring separate specialized systems.
2Power
If conventional split-torque gearbox systems are used, then torque can be distributed through multiple paths, but the system volume increases
Solution Approach 1:
The first stage gear (140) is positioned within the perimeter of the final output gear (160), creating a nested arrangement where the first stage shaft (136) is located above and at least partially within the perimeter of the final output gear. This nesting allows multiple gear stages to occupy overlapping spatial volumes, reducing the overall gearbox envelope while maintaining multiple independent torque transmission paths.
Solution Approach 2:
The design utilizes vertical stacking of gear stages, with the first stage shaft positioned vertically above the final output gear plane. This three-dimensional arrangement allows torque paths to be differentiated by spatial position rather than requiring separate horizontal volumes, enabling multiple independent paths within a compact footprint by exploiting the vertical dimension.
3Strength
If gears are sized larger to assure adequate load capability, then load capability is improved, but the system becomes heavier and more voluminous
Solution Approach 1:
The torque transmission function is segmented across multiple independent paths, each capable of handling a portion of the total load. This segmentation allows each individual gear and shaft to be optimized for its specific load portion rather than being oversized to handle the entire system load, reducing the weight of each component while maintaining adequate load capability through the collective capacity of all paths.
Solution Approach 2:
Each drive train path is designed with sufficient load capability to handle the expected torque distribution, but not excessive capacity for the total system load. The first, second, and third paths are sized appropriately for their designated torque portions, avoiding the waste of oversized components that would be required if a single path had to handle all potential loads independently.
4Power
If conventional split-torque gearbox systems are used, then torque can be distributed through multiple paths, but the system requires unequal load sharing leading to oversized components
Solution Approach 1:
The gearbox is segmented into distinct drive train paths with dedicated gear stages, allowing each path to be independently designed and analyzed for its specific load characteristics. This segmentation simplifies the load sharing problem by breaking it into manageable portions that can be calculated and distributed systematically rather than requiring complex analysis of a monolithic system.
Solution Approach 2:
The system provides equal load sharing capability across the multiple drive train paths, where each path (first, second, and third) is designed to carry an equal portion of the total torque when all are operational. This equal distribution simplifies the complexity by creating symmetric load paths with identical design parameters, eliminating the need for asymmetric component sizing that would result from unequal load sharing.
5Ease of manufacture
If gearbox systems are designed for single aircraft platform, then design is simplified, but adaptability to various platforms is reduced
Solution Approach 1:
The gearbox design achieves universality by creating a modular architecture where the same basic components (gears, shafts, housings) can accommodate multiple engine configurations and positions. The first stage gear can mesh with bevel pinions from different engine locations, and the multiple drive train paths can be selectively activated based on the specific aircraft platform requirements, allowing a single design to serve multiple aircraft types without requiring complete redesigns.
Solution Approach 2:
The design incorporates dynamic adaptability through the optional activation of different drive train paths. The system can dynamically configure which paths are active based on the aircraft platform and operational conditions, with the capability to engage or disengage specific gear stages and shafts. This dynamic reconfiguration allows the same physical gearbox to adapt to different aircraft platforms while maintaining a relatively simple base design.
Data Source
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AI summary
A multi-path split torque gearbox system provides a multiple of three stage toirque split power gewr trains modules that each transmits torque from a high-speed engine to a main rotor shaft (36). The first stage bevel gear arrangement (30,32) provides a compact packaging arrangement that facilitates various eppjne mounting locations in all axes. At the second stage, quill shaft assemblies (40) provide equal load balance. At the third stage, each quill shaft assembly includes a multiple of pinion gears (48) in meshing engagment with the final output gear (28). Each torque split modules transfer the power from the high speed input shaft into a multiple of meshin engagements with the final output gear to provide significant torque transfer desired in a single rotor heavy lift rotary wing aircraft embodiment within a compact housing package.