Vehicle Input Shaft Geometry for Spline Stress and Side Loads
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vehicle input shafts fail due to stress risers at the spline-cylindrical shaft interface and inflexible bearing bosses under extreme side loads, leading to limited operational life.
Innovation Solution
The input shaft design incorporates blend out fillets in spline grooves that interrupt the grooves near the shaft body, providing additional material and reducing stress points, along with a tapered transition and a crowned bearing boss to allow for flexibility under side loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spline grooves exit directly onto the shaft body, then the structure is simpler and easier to manufacture, but stress risers occur at the interface causing shaft failure
Solution Approach 1:
The patent applies curvature by replacing the sharp corner where spline grooves meet the shaft body with a blended fillet surface. This curved transition eliminates the stress concentration that would occur at a sharp corner, distributing stresses more evenly across the transition zone and preventing shaft failure while maintaining manufacturability through standard blending operations.
2Device complexity
If bearing bosses have cylindrical shape with end tapers, then the structure is simpler, but the bosses cannot move freely under extreme side loads causing failure
Solution Approach 1:
The patent transforms the static cylindrical bearing boss into a dynamic structure by adding a crowned (curved) surface. This allows the bearing boss to flex and move freely under extreme side loads, accommodating thermal expansion and mechanical stresses without causing failure, while the crown geometry provides the necessary flexibility without requiring complex mechanisms.
3Reliability
If blend out fillets are added to interrupt spline grooves, then stress points are reduced and durability improves, but manufacturing complexity increases
Solution Approach 1:
The blend out fillet applies a curved transition surface at the termination of spline grooves where they meet the shaft body. This curved fillet eliminates stress concentration points by providing a smooth geometric transition, significantly improving shaft durability and lifespan while being manufacturable through standard CNC blending operations.
Data Source
AI summary
Vehicle input shafts are disclosed. The vehicle input shafts include a bearing boss, a spline portion, a cylindrical shaft body portion and a drive end. The spline portion includes spline teeth and spline grooves that do not exit directly onto the shaft body. Instead, the spline grooves include blend out fillets that interrupt the spline grooves by providing additional material near the shaft body. The bearing boss includes an increased diameter at a central point along its axial length and decreased diameters at its first and second boss ends.