Torque Balancing Gearbox With Helical Distributor
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Solution Overview
Problem
Conventional planetary gearboxes become excessively heavy and impractical for aircraft applications when scaled for large transport aircraft, due to their disproportionate weight increase with size, limiting the achievable power-to-weight ratio.
Innovation Solution
A gearbox design featuring a large array of load-sharing gears, including a distributor gear with helical and spur teeth configurations, allowing for the placement of multiple planet gears in a countershaft arrangement to achieve higher power-to-weight ratios, with the distributor gear acting as an input floatring gear supported by gear tooth mesh forces rather than bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional planetary gearboxes are scaled up for large transport aircraft, then power transmission capacity increases, but weight increases disproportionately (cube function of linear size)
Solution Approach 1:
The patent divides the single-stage planetary gearbox into multiple sequential planetary stages. Each stage handles a portion of the total reduction ratio, distributing the load and torque across multiple smaller gear sets rather than one large gear set. This segmentation allows the system to achieve high power transmission capacity while keeping individual gear components smaller and lighter, thereby reducing overall gearbox weight compared to scaling a single planetary stage.
Solution Approach 2:
The patent transitions from a single-stage planetary configuration to a multi-stage sequential arrangement, adding the dimension of staging. This dimensional change in the gear train architecture allows the system to achieve high reduction ratios and power transmission through series composition of multiple smaller planetary sets, avoiding the cubic weight penalty of scaling up a single planetary stage while maintaining the load-sharing benefits of planetary gearing.
2Power
If the number of planet gears is increased to share load, then power-to-weight ratio improves, but device complexity increases
Solution Approach 1:
The patent segments the high reduction ratio into multiple planetary stages, with each stage using a moderate number of planet gears (typically 3-6). This segmentation allows load sharing within each stage while avoiding the need for an excessive number of planets in a single stage, thereby improving power-to-weight ratio without proportionally increasing device complexity. The modular staged architecture makes the complex system more manageable and maintainable.
Data Source
AI summary
A gearbox comprising a gearset is able to transmit high output torques at high numerical reduction ratios at a power-to-weight ratio higher than previously attainable with existing designs. A distributor gear is disposed relative to a spur gear in order to produce automatic torque balancing. The distributor gear can be advantageously configured as an input floatring gear, for which support in all directions is provided by gear tooth mesh forces rather than bearings. Automatic torque balancing is achieved by configuring the distributor gear with first and second rows of helical teeth on the external circumference, and with a set of double helical teeth disposed on the internal circumference of the distributor gear. This allows for the placement of up to 50 or more planet gears in a countershaft arrangement with one end having helical teeth and the other end having spur teeth.