Hybrid Connecting Rod Torsional Strength via Plastic Profiling

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Solution Overview

Problem

Existing hybrid components for motor vehicle chassis, such as pendulum supports, face challenges in achieving sufficient torsional strength and sealing, particularly when exposed to environmental factors like moisture and corrosion, with current metal connecting rods and ball joints being costly to protect against corrosion.

Innovation Solution

The hybrid component features profiling on the overlapping surfaces of shaft-like extensions and connecting rod ends, including polygonal or hexagonal shapes, labyrinth seals, and thread grooves to enhance torsional strength and sealing, while using plastic injection molding to integrate ball joints and connecting rods, reducing the need for pre-corrosion protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal connecting rods and ball joints are used, then strength and durability are improved, but corrosion protection costs increase and manufacturing complexity increases

Engineering Contradiction:
ImprovestrengthVSAvoidcorrosion protection complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent uses a composite structure combining metal (connecting rod) with plastic (shaft-like extensions and ball joints). The plastic components provide corrosion resistance while the metal provides structural strength, eliminating the need for complex corrosion protection treatments on metal parts.

Inventive Principle:
Principle #40Composite materials

2Reliability

If shaft-like extensions are overlapped to enclose the connecting rod, then sealing is improved, but torsional strength is insufficient

Engineering Contradiction:
ImprovesealingVSAvoidtorsional strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies different local features to different areas of the shaft-like extensions. The overlapping area has profiling (protrusions and recesses) for torsional resistance, while other areas maintain smooth surfaces for sealing. This localized differentiation resolves the contradiction between sealing and torsional strength.

Inventive Principle:
Principle #3Local quality

3Strength

If profiling is added to the overlapping area of shaft-like extensions, then torsional strength is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvetorsional strengthVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent combines the profiling features directly into the injection molding process of the plastic shaft-like extensions. The protrusions and recesses are formed as integral parts of the molding, eliminating the need for separate manufacturing steps or assembly operations, thus avoiding increased manufacturing complexity.

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 design significantly increases torsional strength and ensures effective sealing, reducing the risk of corrosion and moisture ingress, thereby extending the component's lifespan and simplifying production by integrating protective features directly into the manufacturing process.

Implementation Method 1

a metal connecting rod encased by injection molding of coupling parts with shaft-like extensions made of plastic

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

ball joints with plastic housings, which are connected to the connecting rod by overmoulding

Methodology Applied
Scientific EffectOvermolding:

Data Source

PatentEP3500765B1Hybrid component and method for the production thereof
Publication Date: 2021.01.20 ZF FRIEDRICHSHAFEN AG
  • EP3500765B1 patent drawingFigure 1
  • EP3500765B1 patent drawingFigure 2
  • EP3500765B1 patent drawingFigure 3

AI summary

The invention relates to a hybrid component for a chassis of motor vehicles, particularly hybrid connecting rods, consisting of a metal connecting bar (9) with profiled elements arranged on the two end regions (9b, 9c) thereof, and two ball joints (4, 5) with plastic housings (4a, 5a) that are connected to the connecting bar (9) by extrusion, the ball joints (4, 5) comprising shaft-type extensions (6, 7) that surround the connecting bar (9) and overlap on the shaft of the connecting bar (9). The aim of the invention is to seal the shaft (9a) of the connecting bar (9) and to improve the torsional rigidity in such a hybrid component. To this end, a profiled element is arranged in the overlapping region of the shaft-type extensions (6, 7) on the faces facing each other.