Split Torque Transmission with Composite Output Shaft
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Solution Overview
Problem
Existing geared power transmissions have high weight-to-power transmission ratios, which can compromise vehicle design and performance, especially in applications like aircraft and rotorcraft, due to their large size and complexity, and prior split torque solutions have not adequately reduced weight by minimizing the number of gears and support bearings.
Innovation Solution
A split torque geared power transmission using a double-sided bevel face ring gear and cylindrical double pinion arrangement with a high-strength, low-weight fiber-reinforced composite output shaft, reducing the number of gears and support bearings by employing a single or dual pinions that extend through the ring gear's plane and mesh with its teeth, and utilizing a composite material for the output shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional geared power transmissions are used to transmit large amounts of power, then the power transmission capability is improved, but the weight and size increase disproportionately
Solution Approach 1:
The transmission system is segmented into multiple independent pinions that can be arranged in parallel, each handling a portion of the total torque. This segmentation allows the power transmission capability to be increased by adding more pinions rather than scaling up a single large gear system, thereby better managing the weight-to-power ratio through modular architecture.
Solution Approach 2:
Multiple pinions are nested within a common carrier structure that is integrated with the ring gear. The pinions are arranged concentrically or in parallel within the same spatial envelope, allowing multiple power transmission paths to coexist without proportionally increasing the overall transmission size, thus improving power capability while controlling weight growth.
2Weight of moving object
If the number of gears and support bearings is reduced to decrease weight, then the weight is improved, but the structural complexity and reliability may worsen
Solution Approach 1:
Multiple pinions are merged into a single integrated carrier structure that is directly coupled to the ring gear. This merging eliminates the need for separate support bearings for each pinion, reducing the total number of components and weight, while the distributed load path across multiple pinions maintains structural reliability through load sharing.
Solution Approach 2:
The common carrier structure serves multiple functions simultaneously: it supports multiple pinions, transmits torque from all pinions to the ring gear, and provides structural rigidity without requiring additional support bearings. This multi-functionality reduces component count and weight while maintaining reliability through the robust integrated design.
3Weight of moving object
If composite materials are used for the output shaft to reduce weight, then the weight is improved, but the manufacturing complexity may worsen
Solution Approach 1:
The output shaft is constructed from composite materials such as carbon fiber reinforced polymers or other high-strength-to-weight ratio materials. This reduces the output shaft weight significantly compared to traditional metallic shafts, offsetting the increased manufacturing complexity through the weight savings in the overall transmission system.
Data Source
AI summary
A light weight, split torque, geared power transmission having a reduced number of gears and useful for, e.g., transmitting power from an engine to the main rotor of a rotorcraft, includes a ring gear having a pair of oppositely facing angular bevel gears respectively formed on opposite sides of a medial plane thereof, and a first pinion having an elongated drive shaft extending through the medial plane of the ring gear and disposed at an oblique angle relative thereto. The first pinion includes a pair of cylindrical gears mounted coaxially on the drive shaft and respectively disposed in conjugate meshing engagement with respective ones of the bevel gears of the ring gear. An elongated annular output shaft made of a strong, light weight composite material is coupled to a circumferential periphery of the ring gear.