Split-Torque Gearbox Shaft Assembly Without Resonance-Prone Rods
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Solution Overview
Problem
Conventional gearboxes for coaxial rotary-wing aircrafts require complex designs 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 eliminate resonance-sensitive rods, reducing parts and weight while enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional gearboxes use large length over diameter ratio rods to transfer power between gears, then the structural design is simplified, but vibration and high stress occur leading to reduced reliability
Solution Approach 1:
The patent removes the traditional long rod component from the gearbox assembly. Instead of using a rod to connect and transfer power between gears, the invention employs direct gear-to-gear meshing or alternative power transfer mechanisms, thereby eliminating the source of vibration and high stress associated with long length-over-diameter ratio rods while maintaining the simplified structural design
2Ease of manufacture
If conventional gearboxes use traditional rod-based power transfer, then the design is straightforward, but production costs increase due to resonance issues and reliability problems
Solution Approach 1:
The patent adopts a design philosophy that replaces expensive, resonance-prone long rods with simpler, more cost-effective components. The shortened power transfer mechanism uses fewer materials and simpler manufacturing processes, reducing production costs while avoiding the resonance issues that would require expensive mitigation strategies in traditional designs
3Weight of moving object
If shaft assembly uses integrated locking features with reduced length over diameter ratio, then weight is reduced and reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent integrates the locking features directly into the shaft assembly structure, combining what would traditionally be separate components (shaft, locking mechanism, retaining elements) into a unified integrated structure. This merging reduces the overall weight by eliminating separate fasteners and locking components, while the integrated design simplifies manufacturing compared to assembling multiple separate parts
Solution Approach 2:
The shaft assembly is designed with multi-functional integrated features that perform multiple functions simultaneously - structural support, power transfer, and locking/retention. This multi-functionality reduces the need for separate specialized components, thereby reducing weight while maintaining ease of manufacture through standardized multi-purpose elements
Data Source
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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.