Hybrid Transmission Spline Geometry for Debris Ejection
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Solution Overview
Problem
Conventional hybrid transmission components in gas turbine engines face issues with unpredictable interface pressure due to manufacturing variations, leading to excessive wear and mechanical behavior variations, as debris from the composite body gets trapped within the interface, causing inefficiencies and reduced load carrying capability.
Innovation Solution
The hybrid transmission component features a metallic coupling with spline teeth having a curved and planar surface geometry at the leading end, designed to eject debris efficiently, along with chamfered surfaces and grooves to centralize the composite body and minimize interface pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spline tooth design with straight leading end is used, then manufacturing is simple, but debris gets trapped in the interface causing excessive wear and unpredictable interface pressure
Solution Approach 1:
The leading end of the spline tooth is designed with a curved surface instead of a straight surface. The curvature radius is specifically selected to optimize debris ejection while maintaining manufacturing feasibility. This curved geometry enables debris to be lifted out of the interface during assembly, preventing trapping and reducing wear.
Solution Approach 2:
The spline tooth geometry is modified locally at the leading end region while maintaining the overall tooth structure. The curved surface is applied only to the leading end portion where debris generation and trapping occurs, leaving the rest of the tooth geometry unchanged for manufacturing simplicity.
2Strength
If larger diameter and longer interfaces with more spline teeth are used to handle higher load intensity, then load carrying capability increases, but manufacturing variation is magnified causing unacceptably high variation in mechanical behaviour
Solution Approach 1:
The curved leading end geometry provides a self-regulating mechanism where debris ejection is automatically enhanced as interface pressure increases. The curvature radius and rake angle work together to create a feedback loop that maintains consistent debris removal across varying load conditions, reducing the impact of manufacturing variations.
Solution Approach 2:
The spline tooth design incorporates specific geometric parameters including curvature radius and rake angle that are optimized to minimize the magnification of manufacturing variations. These parameter changes enable the interface to maintain consistent pressure distribution even when dealing with larger diameter and longer interfaces required for high load intensity.
3Ease of manufacture
If the leading end of spline teeth directs cutting force away from the composite body surface, then cutting action is achieved, but debris is sheared and lifted out causing trapped debris and excessive wear
Solution Approach 1:
The curved leading end geometry converts the harmful effect of debris generation into a beneficial debris ejection mechanism. The curvature and rake angle work together to use the cutting force itself to lift and eject debris from the interface, transforming the problem of debris generation into a self-cleaning mechanism that reduces wear.
Data Source
AI summary
A hybrid transmission component for a gas turbine engine has a composite body, and a metallic coupling joined with the composite body and defining a longitudinal axis along its length. The metallic coupling includes a plurality of spline teeth extending from a circumferential surface and angularly separated from each other about the longitudinal axis. Each spline tooth from the plurality of spline teeth extends radially from a root to a tip with respect to the longitudinal axis and extends axially from the leading end along the longitudinal axis. The leading end of each spline tooth includes a curved surface extending from the root and a planar surface extending from the curved surface to the tip. The planar surface is inclined obliquely to the longitudinal axis by a rake angle.