Axle Unit Link Element Compression Zone Welding

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Solution Overview

Problem

Existing axle units for commercial vehicles face challenges in achieving high strength and low weight in the connection area between the axle tube and link element, often requiring oversized designs to prevent fatigue fractures, which increases weight and complexity.

Innovation Solution

The axle unit features a link element with a recessed joining area for a weld seam that exclusively connects to the axle tube's compression half, minimizing material stress and allowing for efficient force transmission, while avoiding tensile stress areas to enhance fatigue strength and simplify manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the connection area between axle tube and link element is designed with greater security against fatigue fractures, then the strength and reliability are improved, but the weight of the axle unit increases due to oversizing

Engineering Contradiction:
Improveresistance to fatigue fracturesVSAvoidweight of axle unit
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The recess is positioned specifically in the compression half of the axle tube, creating a localized connection area with optimized material distribution. This local quality enhancement provides high strength where needed (compression zone) while avoiding unnecessary material in other areas, thus improving reliability without increasing overall weight.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The axle tube cross-section is segmented into compression half and tension half, with the connection recess exclusively placed in the compression half. This segmentation allows the design to exploit the different stress characteristics of each half, optimizing the connection for compressive loads while minimizing weight.

Inventive Principle:
Principle #1Segmentation

2Strength

If a weld connection is made between link element and axle tube, then the strength of the connection area is improved, but material damage and manufacturing complexity increase

Engineering Contradiction:
Improvestrength of connection areaVSAvoidmanufacturing simplicity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The weld connection is localized to a specific recess area in the compression half of the axle tube, rather than requiring extensive welding around the entire connection perimeter. This localized approach concentrates the strengthening effect where it is most needed while minimizing the total welding volume and associated manufacturing complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The design accepts that welding introduces some material damage and complexity, but converts this potential harm into benefit by strategically placing the weld in the compression half where the material is under compressive stress. Compressive stresses actually help close any potential weld defects, turning the welding process from purely harmful to beneficial for fatigue resistance.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Force

If the link element encompasses the axle tube at a large angle, then the force transmission is improved, but the weight and material usage increase

Engineering Contradiction:
Improveforce and torque transmissionVSAvoidweight of link element
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

Instead of distributing the connection area uniformly around the axle tube, the recess is concentrated in the compression half, creating a localized force transmission path. This local quality approach provides sufficient force and torque transmission capability while using minimal material, thus reducing weight.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The recess encompasses the axle tube at an angle less than 180 degrees, providing partial rather than complete circumferential connection. This partial action is sufficient to transmit the required forces and torques while significantly reducing the material needed compared to a full 360-degree connection.

Inventive Principle:
Principle #16Partial or excessive action

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 achieves high strength and reduced weight by focusing the weld connection on the compression half of the axle tube, increasing service life and allowing for easier assembly, while minimizing material damage and weight transfer areas.

Implementation Method 1

a welded portion between the link element and the axle tube can be produced in the first joining area

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3191324B1Axle unit
Publication Date: 2021.02.24 SAF HOLLAND GMBH
  • EP3191324B1 patent drawingFigure 1~3
  • EP3191324B1 patent drawingFigure 2

AI summary

The invention relates to an axle unit comprising an axle tube (2) and a link element (4). The axle tube (2) extends substantially along a tube axis (R), and the link element (4) includes a first joining portion (5) designed as a cavity. The link element (4) is arranged so as to extend substantially transversely to the tube axis (R) and in such a way that the first joining portion (5) thereof borders the axle tube (2). A welded section (54) between the link element (4) and the axle tube (2) can be formed in the first joining portion (5).