Variable-Pitch Splined Shaft for Uniform Torque Load Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In planetary gear trains for turbine engines, the absence of a homogeneous load distribution over the circumference of the planet carrier leads to deformation of the splined shaft, resulting in uneven contact between splines, where some become overactive while others are underactive, causing inefficient torque transmission.
Innovation Solution
Modifying the pitch of splines on the splined shaft by introducing a modified pitch that varies sinusoidally or step-wise from the nominal pitch, making some splines more active and others less active to achieve a uniform load distribution across the circumference, thereby ensuring all splines are actively engaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the splines are evenly distributed with nominal pitch, then the manufacturing is simple, but the load distribution becomes non-homogeneous causing deformation and inefficient torque transmission
Solution Approach 1:
The patent applies local quality by varying the pitch of specific splines based on their position in the circumferential direction. Splines are categorized into first pitch splines (with first pitch value) and second pitch splines (with second pitch value), where the pitch values differ to create intentional non-uniform spacing. This local variation in spline geometry compensates for deformation tendencies, ensuring homogeneous load distribution across all splines during torque transmission, thereby resolving the contradiction between manufacturing simplicity and transmission efficiency.
2Reliability
If the pitch of splines is modified to achieve homogeneous load distribution, then torque transmission efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by modifying the pitch parameter of splines at different circumferential positions. Specifically, the pitch values are adjusted to create a controlled non-uniform distribution pattern where first pitch splines and second pitch splines alternate or are strategically positioned. This parameter variation ensures that load is evenly distributed across all splines, preventing deformation and maximizing torque transmission efficiency, while the systematic approach to parameter modification keeps the complexity manageable.
Data Source
AI summary
A splined shaft includes splines evenly distributed over the periphery, wherein the splines being spaced apart from each other. At least one portion of the splines are spaced apart by a modified pitch p with respect to the nominal pitch pn of the splines. The ratio of the absolute value of the difference between the modified pitch and the nominal pitch, to the nominal pitch, i.e. |pn−p|/pn, is different from zero, for example between 0.5 and 5%.