Ball Joint Housing Structure for Precise Sliding Torque

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Solution Overview

Problem

The existing ball joint technology faces challenges in precisely managing torque during the sliding of the ball section with respect to the housing due to molding shrinkage issues during insert injection molding, which affects the stability and performance of the stabilizer link in vehicles.

Innovation Solution

Incorporating a limiting member around the equatorial section of the ball section within the housing to restrict molding shrinkage, ensuring accurate torque management even during insert injection molding processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If insert injection molding is used to form the housing around the ball section, then manufacturing efficiency and integration are improved, but molding shrinkage causes imprecise torque management

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidtorque management precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The limiting member is embedded in the housing at predetermined positions before the molding shrinkage occurs, establishing a mechanical constraint that prevents excessive shrinkage. This preliminary structural arrangement ensures that when the resin housing shrinks during cooling, the limiting member restricts the shrinkage displacement, thereby maintaining precise torque management between the ball section and housing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of uniformly preventing shrinkage throughout the entire housing, the limiting member is strategically embedded only at specific locations where shrinkage would most adversely affect torque management. This localized approach allows the housing to shrink freely in non-critical areas while maintaining precise dimensional control at the ball section interface, optimizing both manufacturing efficiency and torque precision.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If the housing is allowed to undergo natural molding shrinkage, then manufacturing simplicity is maintained, but torque management becomes imprecise

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidtorque management precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The limiting member acts as an intermediary element between the ball section and the housing. It is embedded in the housing to provide a mechanical constraint that mediates the shrinkage process, preventing excessive displacement of the ball section while allowing controlled shrinkage. This intermediary structure maintains torque management precision without requiring complex manufacturing processes or additional adjustment steps.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If the limiting member is embedded in the housing, then torque management precision is improved, but device complexity increases

Engineering Contradiction:
Improvetorque management precisionVSAvoidstructural complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The limiting member is merged with the housing during the insert injection molding process itself. The limiting member is embedded in the housing as an integrated component, combining two elements (housing and limiting member) into a single manufactured assembly. This merging approach improves torque management precision while minimizing the increase in device complexity, as the limiting member becomes an inherent part of the housing structure rather than a separate attachment.

Inventive Principle:
Principle #5Merging (Combining)

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

This solution effectively manages torque between the ball section and the housing, enhancing the stability and performance of the stabilizer link by minimizing the impact of molding shrinkage, thereby maintaining precise control over the sliding motion.

Implementation Method 1

the housing is likely to undergo molding shrinkage (a phenomenon in which the volume of a resin injected into the mold shrinks after cooling)

Methodology Applied
Scientific EffectMolding shrinkage: Thermal Contraction

Data Source

PatentEP3604837B1Ball joint, stabilizer link using ball joint, and stabilizer with stabilizer link
Publication Date: 2023.08.30 NHK SPRING CO LTD
  • EP3604837B1 patent drawingFigure 1
  • EP3604837B1 patent drawingFigure 2A
  • EP3604837B1 patent drawingFigure 2B

AI summary

The ball joint includes a metal ball stud which includes a ball section and a resin housing which rotatably supports the ball section of the ball stud. A limiting member configured to limit molding shrinkage of the housing is embedded in the housing at an interval with respect to an equatorial section of the ball section such that the limiting member is positioned to surround at least the equatorial section of the ball section.