Propeller Shaft Spline Crowning for Stable Collapse Load
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power transmission shafts face instability in collapse loads during collisions due to the insertion of male spline portions into female spline portions, leading to increased friction and potential failure in press-fitting engagement.
Innovation Solution
A power transmission shaft design featuring a crowning portion on the male spline portion, where the tooth thickness gradually increases from the first end portion towards the intermediate portion, stabilizing the collapse load by preventing interference and ensuring smooth meshing with the female spline portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spline portion design is used, then the structure is simple, but the collapse load becomes unstable due to interference and friction during insertion
Solution Approach 1:
The invention applies a crowning portion specifically to the tooth tip surface of the spline, creating a localized variation in tooth thickness. This local modification prevents interference during insertion while maintaining the overall simplicity of the spline structure, thereby stabilizing the collapse load without significantly increasing device complexity.
Solution Approach 2:
The invention changes the geometric parameter of the spline tooth by introducing a crowning portion that gradually increases tooth thickness from the root toward the tip. This parameter modification optimizes the meshing characteristics and reduces friction during insertion, improving collapse load stability while keeping the structural complexity manageable.
2Reliability
If the tooth thickness is uniform throughout the spline portion, then the manufacturing is simple, but interference occurs during insertion leading to unstable collapse load
Solution Approach 1:
Instead of maintaining uniform tooth thickness throughout the entire spline, the invention introduces a crowning portion that creates a gradual thickness variation specifically at the tooth tips. This localized non-uniformity prevents interference during insertion while keeping the manufacturing process relatively simple by affecting only the tooth tip region.
Solution Approach 2:
The crowning portion is designed to preemptively prevent interference by gradually increasing tooth thickness toward the tip, allowing smooth meshing before full engagement. This preliminary geometric adjustment ensures stable collapse load from the beginning of the insertion process, reducing the need for high-precision control throughout the entire tooth structure.
3Reliability
If a crowning portion with gradual tooth thickness increase is added, then the collapse load is stabilized, but the manufacturing process becomes more complex
Solution Approach 1:
The crowning portion is applied only to the tooth tip surface rather than the entire tooth structure, minimizing the additional manufacturing complexity. This localized approach allows standard spline manufacturing processes to be used with an added surface modification step, achieving collapse load stability while maintaining relative ease of manufacture.
Solution Approach 2:
The crowning portion introduces a curved or tapered geometry to the tooth tip surface, creating a gradual thickness increase. While this adds some manufacturing complexity compared to uniform teeth, the curved surface can be produced using conventional machining or forming methods, balancing the improvement in collapse load stability with acceptable manufacturing ease.
Data Source
AI summary
In a propeller shaft, a crowning portion of a male spline portion is provided in a predetermined range including a front end portion in an axial direction, and a tooth tip surface is shaped in such a manner that a tooth thickness thereof gradually increases from the front end portion toward an intermediate portion of the male spline portion in the axial direction.