Axle Unit With Segmented Link Elements For Torsional Load Distribution

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Solution Overview

Problem

Existing axle units for commercial vehicles face challenges in absorbing torsional moments at the connection area between the axle tube and trailing arms, leading to potential damage and requiring heavy designs for safety, which increases weight and manufacturing complexity.

Innovation Solution

The axle unit features a design with two pivotable link elements that form a trailing link, each with a recessed joining area on opposite sides of the axle tube, allowing for a welded connection that optimally distributes torsional loads and reduces weight by using staggered and offset joining areas for improved strength and manufacturing simplicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If over-dimensioning is used to increase safety margin against fatigue fractures, then reliability is improved, but weight increases

Engineering Contradiction:
Improvesafety margin against fatigue fracturesVSAvoidaxle unit weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The control arm is divided into two separate control arm halves that are connected to each other and to the axle tube. This segmentation allows for optimized load distribution and reduces the need for over-dimensioning the entire control arm, thereby reducing weight while maintaining reliability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The joining areas on the control arm halves are specifically designed with rounded or curved surfaces that match the curvature of the axle tube. This local optimization of the joining areas improves stress distribution and fatigue resistance at critical locations without requiring overall over-dimensioning of the entire control arm structure

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If traditional welded connections are used to connect control arms to axle tube, then manufacturing simplicity is maintained, but damage to welds occurs under torsional moments

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidweld damage resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The control arm halves are designed to be pivotably mounted on the vehicle frame, allowing dynamic movement and load distribution. This dynamic capability enables the connection to better absorb torsional moments through controlled movement rather than rigid welding alone, reducing weld damage while maintaining manufacturing simplicity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The joining areas are designed with rounded or curved surfaces that match the curvature of the axle tube. This curved geometry distributes stresses more evenly across the weld joints, preventing stress concentration and weld damage under torsional loads, while still allowing for straightforward welding manufacturing processes

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Strength

If heavy design is used to ensure sufficient strength in connection area, then strength is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveconnection area strengthVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

Dividing the control arm into two halves with dedicated joining areas simplifies the manufacturing process compared to creating a single heavy-duty integrated structure. Each half can be manufactured separately and then assembled, reducing overall manufacturing complexity while maintaining connection strength

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The joining areas are locally optimized with specific curved geometries that enhance strength where needed, rather than requiring the entire control arm to be over-dimensioned. This localized strengthening approach reduces manufacturing complexity by focusing material and design effort only where structural demands are highest

Inventive Principle:
Principle #3Local quality

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 enhances the strength and service life of the axle unit while reducing weight by effectively transmitting torsional moments and simplifying the manufacturing process, allowing for a lighter and more robust axle unit.

Implementation Method 1

the first and second control arm elements can be bonded to the axle tube in the first and second joining areas

Methodology Applied
Scientific EffectWelding: Welding

Implementation Method 2

the first and second control arm elements can be bonded to the axle tube in the first and second joining areas

Methodology Applied
Scientific EffectMaterial bonding: Adhesive

Data Source

PatentEP3191322B1Axle unit
Publication Date: 2019.08.21 SAF HOLLAND GMBH
  • EP3191322B1 patent drawingFigure 1~2
  • EP3191322B1 patent drawingFigure 3~4
  • EP3191322B1 patent drawingFigure 5

AI summary

An axle unit, comprising a first link element and a second link element, wherein the first link element and the second link element can be mounted on a vehicle frame so as to be pivotable about a common pivot axis, wherein the first link element has a first joining region designed as a recess, and the second link element has a second joining region designed as a recess, wherein the first joining region and the second joining region are arranged on two opposites sides of an axle tube extending substantially along a tube axis, and wherein the axle tube can be secured in an integrally bonded manner in the first and second joining region to the first and second link element.