Ball Joint Assembly Axial Float Prevents Memory Steer
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Solution Overview
Problem
Vehicle suspension systems experience 'memory steer' due to binding of the stud during installation in ball joint assemblies, leading to uneven steering and handling performance.
Innovation Solution
A ball joint assembly with a housing and ball stud design that includes a pair of bearings with curved surfaces for rotation and articulation, and biasing elements made of elastically compressible material to allow axial movement of the ball stud, preventing binding and improving installation and operational performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stud is urged in one axial direction during installation, then the stud binds against one of the bearings, but this causes memory steer phenomenon where the vehicle wants to keep turning
Solution Approach 1:
The ball stud is designed with freedom of axial movement rather than being fixed in position. The stud can move axially within the bore to accommodate installation forces in either direction, preventing binding against the bearings while maintaining reliable steering operation. This dynamic adjustment capability resolves the contradiction between reliable steering performance and ease of installation.
2Stability of the object's composition
If the ball stud is fixed axially, then the structure is stable, but the ball joint assembly binds during installation causing memory steer
Solution Approach 1:
The patent changes the axial position parameter of the ball stud from fixed to variable. The stud is permitted to move axially within the bore, allowing it to adjust its position to accommodate installation forces while maintaining structural stability through the bearing support and cage constraint. This parameter change eliminates memory steer while preserving structural integrity.
3Ease of manufacture
If conventional ball joint assembly is used, then manufacturing is standard, but it results in binding and memory steer issues
Solution Approach 1:
The invention introduces axial mobility to the ball stud within the conventional ball joint assembly structure. The stud can move freely in the axial direction within the bore, preventing binding during installation while maintaining compatibility with standard manufacturing processes. The cage and bearing arrangement remains conventional, ensuring ease of manufacture while improving steering performance.
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 design prevents binding during installation and enhances steering and handling performance by allowing the ball stud to float axially, reducing the occurrence of 'memory steer' and improving manufacturing cost-effectiveness.
Implementation Method 1
a pair of biasing elements which bias the bearings in opposite axial directions against the ball portion of the ball stud
Implementation Method 2
Each of the bearings has a curved inner bearing surface which is in surface-to-surface contact with the ball portion of the ball stud for allowing the ball stud and the housing to rotate and articulate relative to one another
Data Source
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AI summary
The ball joint assembly (20) includes a housing (26) with an inner wall (40) that surrounds an axially extending open bore. A ball portion (48) of a ball stud is received in the open bore of the housing, and a shank portion (50) of the ball stud projects out of the open bore. A pair of bearings (56, 58) are disposed in the inner bore of the housing and are interposed between the ball portion and the inner wall. Each bearing has a curved bearing surface (60, 62) which slidably contacts the ball portion for allowing the ball stud and the housing articulate relative before use. Each bearing also has an outer surface (64, 66) that slidably contacts the inner wall. A pair of biasing elements (70, 72) bias the bearings in opposite directions against the ball portion of the ball stud such that the ball stud is movable relative to the housing in the axial direction before use of the assembly.