Ball Joint Collar Structure to Prevent Outer Race Pull-Out
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Solution Overview
Problem
Ball joints fail due to radial expansion of the outer race, causing the ball and stem to pull out under axial loads, which is not effectively prevented by existing designs with insufficient radial thickness in the stepped flange.
Innovation Solution
An anti pull-out collar in the form of an annular ring with a radially inward facing surface, featuring a profile with varying diameters and a shoulder, providing an interference fit and heat-treated metallic material for enhanced stiffness and fatigue resistance, to prevent radial expansion and maintain torque stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radial thickness of the stepped flange is increased to prevent radial expansion, then the ball joint reliability improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention divides the load-bearing function into two separate components: the original stepped flange and the additional anti-pull-out collar. The collar is a separate ring-shaped component that fits over the outer race, allowing the original flange design to remain unchanged while adding specific reinforcement where needed. This segmentation enables targeted strengthening without redesigning the entire assembly.
Solution Approach 2:
The anti-pull-out collar is designed as a ring-shaped component that fits concentrically over the outer race of the ball joint, similar to a nested doll structure. The collar's inner diameter matches the outer race's outer diameter, creating a nested configuration where the collar encircles the outer race. This nesting approach allows the collar to provide radial support without interfering with the internal ball joint mechanisms.
2Reliability
If the radial thickness of the stepped flange is increased to prevent radial expansion, then the ball joint reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
By separating the reinforcement function into a distinct collar component, the manufacturing precision requirements are localized to the collar's interface dimensions rather than requiring high precision throughout the entire flange structure. The collar can be manufactured separately with controlled tolerances for its inner diameter, outer diameter, and axial position, while the original outer race and flange maintain their existing manufacturing specifications.
Solution Approach 2:
The anti-pull-out collar acts as an intermediary component between the outer race and the stepped flange. It provides the necessary radial support and load distribution without requiring direct modification of the outer race or flange geometry. The collar's intermediate position allows it to bridge the gap between the ball joint's moving components and the stationary housing, providing reinforcement through its structural presence rather than through complex precision features.
3Force
If the anti pull-out collar is added to prevent radial expansion, then the load capacity increases, but the device complexity increases
Solution Approach 1:
The load-bearing function is segmented between the original stepped flange and the added anti-pull-out collar. The collar specifically handles radial expansion forces and pull-out loads, while the flange maintains its original functions of axial positioning and mounting. This functional segmentation allows each component to be optimized for its specific role, with the collar providing enhanced load capacity through its radial thickness and material properties without requiring changes to the flange design.
Solution Approach 2:
The nested configuration of the collar over the outer race allows the load capacity enhancement to be achieved without adding external complexity to the overall assembly. The collar integrates into the existing ball joint structure, fitting within the available radial space and aligning with the outer race's geometry. This nested approach enables the additional load-bearing capability to be incorporated seamlessly into the existing design framework.
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 anti pull-out collar effectively prevents radial expansion of the outer race, thereby preventing ball joint failure under pull-out loads, increasing load capacity and maintaining operating torque within a predetermined range.
Implementation Method 1
The first inside diameter and/or the second inside diameter have a magnitude configured for an interference fit on the exterior surface of the ball joint
Implementation Method 2
the anti pull-out collar is made from a metallic material that is heat treated to obtain predetermined stiffness and fatigue resistance
Data Source
AI summary
A ball joint includes an outer race having an exterior surface extending from an outer axial end to an inner axial end thereof and having an interior that has an opening proximate the outer axial end. The ball joint includes a ball with a stem extending therefrom. The ball is disposed in the interior area with the stem extending out of the opening. The ball joint has an anti pull-out collar disposed around the outer race and located entirely beyond a center point of the ball towards the outer axial end of the outer race. The anti pull-out collar has a radial thickness configured to prevent radial expansion of the outer race.