Aircraft Gearbox Shaft Offset Layout for Load Alignment
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Solution Overview
Problem
Existing power transmission systems in aircraft face significant parasitic forces due to misalignment between drive and driven shafts, leading to wear and damage, and existing solutions either increase weight or are costly.
Innovation Solution
A transmission system with misaligned drive and driven axes at rest, allowing them to align under load, reducing parasitic forces through a connecting device and guide devices that tolerate initial misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drive shaft and driven shaft are aligned and coaxial, then the system structure is simple and manufacturing is easy, but parasitic forces increase due to misalignment under load causing wear and damage
Solution Approach 1:
The patent applies preliminary action by pre-misaligning the drive shaft and driven shaft axes during assembly. The housing is designed with offset mounting positions for the drive shaft and driven shaft, creating an intentional initial misalignment. This preliminary misalignment compensates for the deformation that occurs under operating conditions, allowing the shafts to become properly aligned when the transmission system is under load, thereby reducing parasitic forces and improving reliability
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameters of the housing, specifically the positions of the mounting holes for the drive shaft and driven shaft. The housing features offset mounting positions that create a controlled angular and radial misalignment between the two shafts. This parameter modification allows the system to tolerate and compensate for misalignment, reducing parasitic forces while maintaining manufacturing simplicity
2Reliability
If rigid housing is used to limit misalignment amplitudes, then misalignment is controlled, but system weight increases
Solution Approach 1:
The patent applies preliminary action by pre-setting the optimal misalignment parameters in the housing design. Instead of using a heavy rigid housing to constrain misalignment, the housing is designed with built-in offset mounting positions that pre-compensate for expected deformations under load. This eliminates the need for excessive rigidity and reduces housing weight while maintaining effective misalignment control
Solution Approach 2:
The patent applies parameter changes by optimizing the geometric parameters of the housing mounting positions. The offset distances and angular relationships are carefully calculated to provide the necessary misalignment compensation for expected operating conditions. This parameter optimization allows the housing to be lighter while still achieving the required misalignment control, avoiding the need for heavy rigid structures
Data Source
AI summary
The transmission system, including a drive shaft, a driven shaft and a connecting device enabling the drive shaft to transmit mechanical torque to the driven shaft, and guide devices guiding the drive shaft in rotation about a drive axis and guiding the driven shaft in rotation about a driven axis. When the transmission system is at a standstill, the drive axis and the driven axis are misaligned, and they move closer to one another when the transmission system transmits torque from the drive shaft to the driven shaft.