Hollow Stub Element Axle System for Utility Vehicles

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Solution Overview

Problem

Existing axle systems for commercial vehicles are heavy, complex, and expensive to manufacture due to their compact design, which limits space for payload storage and requires a large number of weld seams.

Innovation Solution

A hollow, plane-symmetrical stub element with a support area that is compact in the axial direction, featuring a support length smaller than the mean outer diameter, allowing for high area moments of inertia and reduced material stress, combined with a holding element like a trailing arm for independent wheel suspension, using friction welding for fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the stub axle is designed as a very short, compact component to maximize storage space, then the available installation space for wheel suspension is increased, but the component becomes very heavy and requires numerous welds

Engineering Contradiction:
Improvestorage space between wheel suspensionsVSAvoidweight of stub axle
Core Design Contradiction:
Volume of moving objectVSWeight of moving object

Solution Approach 1:

The stub axle is divided into two separate components: a hollow stub element and a separate holding element. These segments are connected through friction welding, allowing each component to be optimized independently for weight and strength while maintaining the compact overall design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses composite construction by combining the hollow stub element with the holding element through friction welding. This composite approach allows the hollow section to provide structural strength with reduced weight compared to a solid stub axle

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If the stub axle is designed as a very short, compact component, then storage space is maximized, but the manufacturing complexity and cost increase due to numerous welds

Engineering Contradiction:
Improvestorage space between wheel suspensionsVSAvoidmanufacturing complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

By segmenting the stub axle into two friction-welded components, the design reduces the total number of weld seams required compared to traditional solid stub axles that require multiple attachment points for various components

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hollow stub element serves multiple functions simultaneously: it provides structural support, reduces weight, and the friction welding process creates a self-reinforcing connection where the fit between components enhances the joint strength

Inventive Principle:
Principle #25Self-service

3Strength

If the support length is increased to provide sufficient force transmission area, then the area moment of inertia increases, but the axial length becomes too large reducing storage space

Engineering Contradiction:
Improveforce transmission capabilityVSAvoidaxial length of stub element
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

The invention transitions from increasing strength through axial length to achieving strength through radial dimension. The hollow stub element has a large outer diameter that provides sufficient area moment of inertia and force transmission area while maintaining a short axial length, effectively moving the strength solution to another dimension

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The composite structure of the hollow stub element combined with the holding element creates a design where the radial dimensions provide the necessary structural properties for force transmission without requiring increased axial length

Inventive Principle:
Principle #40Composite materials

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

The solution results in a lightweight, cost-effective axle system capable of transmitting large forces and torques while maximizing storage space between wheel suspensions, with reduced material usage and lower production complexity.

Implementation Method 1

the area moment of inertia in the connection area between the axle system and the stub element can be kept particularly high, thereby keeping the stresses occurring in the material low even under large forces and bending moments

Methodology Applied
Scientific EffectArea moment of inertia: Moment of Inertia

Implementation Method 2

using friction welding for fixation

Methodology Applied
Scientific EffectFriction welding: Friction Welding

Data Source

PatentEP3592572B1Stub element and axle system
Publication Date: 2020.09.16 SAF HOLLAND GMBH
  • EP3592572B1 patent drawingFigure 1~2
  • EP3592572B1 patent drawingFigure 3~4

AI summary

The invention relates to an axle system, in particular for use in a utility vehicle, comprising a stub element and a retaining element; the stub element has a supporting zone in which same can be or is secured to a retaining zone on the retaining element, and the stub element is substantially plane-symmetrical to two planes intersecting in a stub axis and is hollow at least in the area of the supporting zone.