Rear Toe Link Inner Ball Joint With Press-Fit Stud Assembly
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Solution Overview
Problem
Manufacturing a single-piece inner ball joint with a long threaded stud for vehicles without rear wheel steering systems is not feasible, leading to issues with strength, cost, and mass in existing welded or threaded-on two-piece designs.
Innovation Solution
A press-fit two-piece design for the inner ball joint, comprising a ball joint housing and a stud with splines or knurling, is used to create a strong and cost-effective connection to the cradle/frame, utilizing a mechanical interlock for high loading conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single-piece inner ball joint with a long threaded stud is manufactured, then the stud length is sufficient for connection to cradle/frame in vehicles without rear wheel steering, but manufacturing feasibility deteriorates and costs increase
Solution Approach 1:
The inner ball joint is divided into two separate components: a ball joint housing and a stud assembly. The stud assembly includes a stud with a press-fit portion that inserts into the housing. This segmentation allows the stud to be manufactured separately with optimal length for non-steered vehicles, while the housing provides the ball joint functionality. The press-fit connection ensures structural integrity without requiring a single-piece construction with excessively long studs.
Solution Approach 2:
A press-fit interface serves as an intermediary connection mechanism between the stud and housing. This press-fit portion on the stud inserts into a corresponding bore in the housing, creating a strong mechanical connection that eliminates the need for welding or threading. The press-fit design allows for cost-effective manufacturing while maintaining sufficient stud length for connection to the cradle or frame in vehicles without rear wheel steering systems.
2Ease of manufacture
If welded or threaded-on two-piece designs are used, then manufacturing feasibility is maintained, but structural integrity and strength deteriorate under high loading conditions
Solution Approach 1:
The patent replaces traditional welding or threaded connections with a press-fit mechanical interference connection. The press-fit portion of the stud creates a friction-based mechanical lock within the housing bore, providing superior strength and rigidity compared to welded or threaded designs. This mechanical press-fit connection maintains structural integrity under high loading conditions while preserving manufacturing feasibility through simple assembly processes.
3Length of moving object
If a single-piece design with long stud is attempted, then stud length requirement is met, but mass and manufacturing costs increase
Solution Approach 1:
By segmenting the inner ball joint into separate housing and stud components, the design allows optimization of material usage. The stud can be manufactured with the exact length needed for connection to the cradle or frame, without requiring additional material for a single-piece construction. This segmentation enables precise material allocation, reducing overall mass and manufacturing costs while meeting the stud length requirement for non-steered vehicle applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The two-piece design provides sufficient stud length, avoids warping, and reduces costs compared to prior designs, while maintaining structural integrity under high loads.
Implementation Method 1
press fitting the shoulder of the stud into the bore in the first surface of the ball joint housing
Implementation Method 2
A portion of an outer surface of the shoulder is knurled
Implementation Method 3
an outer surface of the shoulder includes one or more splines. The bore in the first surface includes one or more slots to receive the one or more splines
Data Source
AI summary
A ball joint for a rear toe link includes a ball joint housing including a cylindrical wall, a first surface extending between the cylindrical wall at a first end thereof, and a bore in the first surface. A stud includes a head, a shoulder extending from the head, and a shaft extending from the shoulder. The shoulder is inserted into the bore in the first surface of the ball joint housing and the head is arranged adjacent to an inner side of the first surface. A ball/rod portion includes a ball and a rod extending from the ball.