Ball Joint Assembly With Segmented Bearing Surfaces
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Solution Overview
Problem
Ball joint assemblies in automotive steering and suspension systems face issues with wear-induced changes in contact angles and clearances, leading to increased rotational torque and reduced lifespan due to varying axial and radial loads, as well as rotational forces.
Innovation Solution
A ball joint assembly design featuring a housing with a semi-spherically curved first contact surface and a cylindrical second contact surface, along with a separate exit bearing biased against the ball stud, maintains minimal clearance and constant contact area, reducing wear and rotational torque through lubrication and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the curved contact surfaces of the bearings are provided with a very similar diameter to the diameter of the ball portion, then the clearance between the ball portion and the bearings is minimized, but the contact area increases leading to higher rotational torque values as wear occurs
Solution Approach 1:
The first bearing is divided into two separate contact surfaces: a semi-spherically curved first contact surface and a cylindrical second contact surface. This segmentation allows each surface to perform a specific function - the curved surface maintains minimal clearance for stability while the cylindrical surface provides a larger diameter for reduced contact pressure and torque
Solution Approach 2:
Different regions of the bearing structure are given different geometric properties - the first contact surface has a semi-spherical curvature matching the ball portion for minimal clearance, while the second contact surface has a cylindrical shape with larger diameter to reduce contact area and pressure, creating local optimization of contact characteristics
2Force
If the curved contact surfaces of the bearings are provided with a greater diameter than the diameter of the ball portion, then the contact area is minimized reducing rotational torque values, but the clearance between the ball portion and the bearings increases reducing expected life
Solution Approach 1:
The bearing is segmented into two distinct contact surfaces with different diameters - the first contact surface with smaller diameter for minimal clearance and the second contact surface with larger diameter for reduced contact pressure, combining the benefits of both approaches
Solution Approach 2:
The solution transitions from a single-dimensional contact surface to a two-dimensional contact system with surfaces of different diameters, allowing simultaneous optimization of clearance (via the first surface) and contact pressure (via the second surface)
3Stability of the object's composition
If minimal clearance is provided between the ball portion and the bearings, then movement of the ball portion is limited improving stability, but wear causes contact angles and clearances to change increasing rotational torque
Solution Approach 1:
The second contact surface is designed with a larger diameter in advance to compensate for future wear, and the second bearing is pre-biased against the ball portion to maintain constant contact, preventing torque increase before wear occurs
Solution Approach 2:
The system uses two different contact surface diameters to create different clearance parameters - the first contact surface provides minimal radial clearance for stability while the second contact surface provides axial contact with biased positioning, maintaining stable geometric parameters despite wear
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 enhances the operating life and rotational torque performance of the ball joint assembly by minimizing clearance and maintaining constant contact areas despite wear, thereby improving the service life and reducing rotational torque over time.
Implementation Method 1
The first and second contact surfaces are in sliding contact with the ball portion of the ball stud, and the first contact surface is semi-spherically curved with a generally constant diameter. The second contact surface is generally cylindrical in shape. A second bearing, which is formed as a separate piece from the first bearing, is at least partially disposed in the open interior of the housing. The second bearing has a third contact surface which is in sliding contact with the ball portion of the ball stud and is biased against the ball portion.
Data Source
Figure 1~3
Figure 4~6
AI summary
The ball joint assembly (20) includes a housing (22) with an open interior and which extends from a closed end (24) to an open end (26). A stud ball (68) with a ball portion (72) is disposed in the open interior of the housing (22). A first bearing (52, 54) is also disposed in the open interior and includes first (64) and second (58) contact surfaces which are spaced from one another by a gap. The contact surfaces (64, 58) are in sliding contact with the ball portion (72) of the ball stud (68), and the first contact surface (64) is semi- spherically curved with a generally constant diameter while the second contact surface (58) is generally cylindrical in shape. A second bearing (74) is disposed in the open interior of the housing (22) and has a third contact surface (76) which is in sliding contact with the ball portion (72) of the stud ball (68) and is biased against the ball portion (72).