Ball Joint Spring Element Wear Compensation
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Solution Overview
Problem
Ball joints, particularly axial joints, face issues with thermal expansion leading to increased torque and wear due to material creep, resulting in play and potential failure under high mechanical and thermal loads, especially in motor vehicle applications.
Innovation Solution
A ball joint design with a one-piece ball socket incorporating a spring element integrated into the ball shell, featuring partial interruptions to prevent wear and play, and a deformed shell with varying material thickness to manage thermal expansion and mechanical loads, allowing for a compact and cost-effective solution without separate adjustment elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If continuous slots are provided in the ball shell to accommodate thermal expansion, then thermal stress is reduced, but the ball shell develops increased tendency to creep and experiences reduced material strength leading to play in the joint
Solution Approach 1:
The spring element is divided into multiple segments or coils along its length, allowing it to compress and expand in a controlled manner. This segmentation enables the element to accommodate thermal expansion of the ball shell while maintaining continuous contact and preventing material creep into the slots, thereby preventing joint play.
Solution Approach 2:
The spring element's physical parameters (stiffness, coil density, material properties) are specifically designed to provide the right balance between accommodating thermal expansion and preventing creep. By adjusting these parameters, the element can absorb thermal stresses without allowing the ball shell to deform permanently or develop play.
2Ease of manufacture
If the ball shell material thickness is reduced to lower weight and cost, then manufacturing cost decreases, but the ball shell becomes more susceptible to creep and wear under high thermal and mechanical loads
Solution Approach 1:
The spring element is positioned specifically in the lower area of the ball socket where it can provide localized support and counteract creep tendencies. This local reinforcement allows the rest of the ball shell to maintain reduced thickness for cost and weight benefits, while the spring element provides the necessary structural support in the critical load-bearing region.
Solution Approach 2:
The spring element acts as a preventive measure against creep and wear by maintaining constant contact pressure between the ball shell and ball pivot. This beforehand cushioning effect compensates for thermal expansion and mechanical loads before they can cause permanent deformation or material loss, protecting the thinner-walled ball shell from failure.
3Reliability
If a separate elastic adjustment element is added to compensate for wear and minimize play, then joint stability is improved, but device complexity and production cost increase
Solution Approach 1:
The spring element is integrated directly into the ball socket structure, forming a single-piece component. This merging of the socket and spring element eliminates the need for separate adjustment elements that would otherwise be required to compensate for wear and maintain joint stability. The spring element becomes an inherent part of the ball socket rather than an auxiliary component.
Solution Approach 2:
The integrated spring element performs multiple functions simultaneously: it accommodates thermal expansion, compensates for wear, prevents joint play, and provides structural support. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall device complexity while maintaining joint stability.
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 load capacity, prevents joint play, maintains constant friction torques across temperatures, and reduces production costs by integrating the spring element into the ball shell, ensuring stability and efficient load distribution.
Implementation Method 1
the spring element integrated into the ball shell has at least partial interruptions, so that play and/or wear within the ball joint can be prevented by the spring element
Implementation Method 2
At high temperatures within the ball joint, which in the case of axial joints are caused, for example, by direct coupling to a steering system at operating temperature, the ball shell expands
Implementation Method 3
Ball shells with continuous slots known from the prior art, e.g. from EP 0 846 611, such as a snap-on shell, are unsuitable due to the disadvantage of an increased tendency to creep and a smaller bearing surface, since the ball shell does not lie flat on the housing due to the slots and thus creep of the material into the space between the slots
Data Source
Figure 1~4B
AI summary
The invention relates to a ball joint (1), in particular an axial joint, having a ball pin received in a ball socket (2), which are accommodated in a ball housing (5), the ball socket being formed in one piece comprising at least one spring element (13) in a region of the ball socket that faces away from the joint housing opening, wherein the spring element has discontinuities, in particular as a result of slots, such that compensation for wear within the ball joint is provided by the spring element.