Split-Torque Gearbox Shaft Assembly for Vibration-Stable Gears
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Solution Overview
Problem
Conventional gearboxes for rotary wing aircraft with complex rotor systems, particularly coaxial configurations, face issues with large length over diameter ratio rods that cause vibration and high stress, leading to reduced reliability and increased production costs.
Innovation Solution
A shaft assembly with integrated locking features and reduced length over diameter ratio, incorporating a shaft, lock mechanism, and retaining extensions to stabilize gear components, reducing the number of parts and weight while enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gearboxes use large length over diameter ratio rods to connect gears, then the structural simplicity is maintained, but vibration and high stress occur leading to reduced reliability
Solution Approach 1:
The shaft assembly is segmented into multiple functional components: a shaft body with first and second ends, a lock mechanism with projecting portions, and retaining extensions. This segmentation allows each component to perform its specific function optimally while reducing overall vibration and stress in the gearbox system.
2Ease of manufacture
If the number of parts is reduced to lower production costs, then manufacturing simplicity improves, but component stability may be compromised
Solution Approach 1:
Multiple functions are merged into the shaft assembly: the shaft body provides structural support, the lock mechanism secures gear positioning, and retaining extensions maintain component stability. This merging reduces the total number of separate parts needed while maintaining or improving component stability and reducing production costs.
Solution Approach 2:
The shaft assembly serves multiple functions simultaneously: it acts as a structural support element, a locking mechanism for gear positioning, and a retaining structure for stabilizing components. This multi-functionality reduces the need for separate dedicated parts, lowering production costs while maintaining stability.
3Productivity
If resonance-sensitive rods are eliminated to reduce weight and cost, then productivity improves, but alternative structures are needed to maintain gear component stability
Solution Approach 1:
The resonance-sensitive rod is extracted and removed from the gearbox system. Its stabilizing function is replaced by the integrated shaft assembly with lock mechanism and retaining extensions, which provides comparable or superior stability without the resonance issues, enabling weight and cost reduction.
Solution Approach 2:
The invention replaces expensive, resonance-prone rod components with a more cost-effective shaft assembly design that achieves the same stabilizing function. This substitution reduces material costs and manufacturing complexity while maintaining component stability.
Data Source
AI summary
A coaxial rotary-wing aircraft including a first rotor rotatable about a first axis in a first direction, a second rotor rotatable about the first axis in a second direction to provide lift, and a gearbox. The gearbox includes a first gear oriented to rotate about an axis, a second gear spaced from the first gear and oriented to rotate about the axis, and a shaft assembly extending between the first gear and the second gear. The shaft assembly includes a shaft, a lock mechanism, and a retaining extension. The shaft has a first end coupled with the first gear and a second end coupled with the second gear, the second end including at least one recess formed on an end face. The lock mechanism is removably coupled to the second end of the shaft.