Double Cardan Joint Spring Centering Without Ball-Joint Seals

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Solution Overview

Problem

Conventional double cardan joints require an expensive aligning ball-joint for centering and alignment, which increases costs and requires grease that can become contaminated, necessitating additional sealing measures and potential disassembly for maintenance.

Innovation Solution

Incorporating a resilient member, such as a spring or elastic component, between the universal joints to center and align the double cardan joint, eliminating the need for the aligning ball-joint and associated sealing complexities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an aligning ball-joint is used to center and align the double cardan joint, then the joint can be properly centered and aligned, but the cost increases and grease contamination becomes an issue

Engineering Contradiction:
Improvecentering and alignment capabilityVSAvoidcost and sealing requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the aligning ball-joint from the double cardan joint assembly and replaces it with a spring-based centering mechanism. This extraction eliminates the need for grease-lubricated components and complex sealing arrangements, directly reducing cost and complexity while maintaining the centering and alignment function through the elastic properties of the spring.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the mechanical aligning ball-joint system with an elastic spring mechanism. The spring provides the necessary centering force through its elastic deformation, replacing the grease-dependent ball-joint mechanism with a maintenance-free elastic element that achieves the same centering and alignment objective without requiring lubrication or sealing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If grease is used in the aligning ball-joint, then the joint functions properly, but contamination can occur requiring disassembly for maintenance

Engineering Contradiction:
Improvejoint functionalityVSAvoidmaintenance complexity
Core Design Contradiction:
Ease of operationVSEase of repair

Solution Approach 1:

The spring-based centering mechanism is inherently maintenance-free and does not require external lubrication or sealing. The elastic element self-regulates through its material properties, eliminating the need for periodic grease replacement or contamination monitoring that would require disassembly and maintenance intervention.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If a sleeve is added to seal the double cardan joint, then contamination is prevented, but cost and complexity increase

Engineering Contradiction:
Improvecontamination protectionVSAvoidstructural complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent eliminates the need for sealing sleeves by removing the grease-lubricated aligning ball-joint that would require such sealing. The spring-based mechanism has no lubrication requirements, thereby extracting the entire sealing subsystem and its associated complexity and cost.

Inventive Principle:
Principle #2Taking out (Extraction)

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 reduces the overall cost of the double cardan joint by eliminating the expensive ball-joint and associated sealing requirements, while also simplifying maintenance and reducing the risk of contamination.

Implementation Method 1

a resilient member positioned between the universal joints to center and align the double cardan joint. The resilient member is adapted to support the input and output shafts

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4047232B1Spring guided double cardan joint
Publication Date: 2025.06.18 VOLVO CAR CORP
  • EP4047232B1 patent drawingFigure 1
  • EP4047232B1 patent drawingFigure 2
  • EP4047232B1 patent drawingFigure 3

AI summary

A double cardan joint assembly (200) including an input universal joint, an output universal joint, and a resilient member (235) disposed between the input universal joint and the output universal joint. The resilient member (235) is positioned between the input universal joint and the output universal joint by attachment to either an arc guard (211, 221) of each universal joint or a cross-member (215, 225) of each universal joint, for example. The resilient member (235) is adapted to center and align the double cardan joint assembly (200). Thus, the double cardan joint assembly (200) does not necessarily include a conventional aligning ball-joint.