Vehicle Suspension Leaf Spring Assembly Weight Reduction

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Solution Overview

Problem

Conventional single leaf springs for commercial vehicles are expensive, heavy, and prone to failure, with existing alternatives like plastic and composite materials being impractical due to high costs and insufficient strength, and require costly safety systems for secure installation.

Innovation Solution

A suspension system using a pair of side-by-side parabolic leaf springs with a predetermined spacing, which maintains the same total width as a conventional single leaf spring, allowing for weight reduction and elimination of safety systems, while ensuring mechanical properties are comparable or superior to traditional designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single leaf spring is used to reduce weight and manufacturing cost, then the number of parts is reduced and manufacturing complexity decreases, but the spring must be manufactured to high precision which increases manufacturing cost

Engineering Contradiction:

Improvenumber of spring partsVSAvoidspring manufacturing precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The single leaf spring is divided into multiple individual leaf springs (typically three) arranged side-by-side. Each leaf spring can be manufactured separately to standard specifications using conventional equipment, avoiding the need for expensive specialized tapered rolling machines while achieving the desired precision and performance characteristics.

Inventive Principle:

Principle #1Segmentation

2Weight of moving object

If plastic or composite materials are used to reduce spring weight, then the spring weight decreases, but the material cost increases and structural integrity becomes insufficient

Engineering Contradiction:

Improvespring weightVSAvoidspring strength and durability

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent uses a composite structure combining multiple steel leaf springs with rubber bumpers or elastomeric elements. This composite approach maintains the strength and durability of steel while the elastomeric components provide damping and reduce overall weight compared to solid steel construction, achieving both weight reduction and structural integrity.

Inventive Principle:

Principle #40Composite materials

3Strength

If a conventional single leaf spring design is used, then the spring provides sufficient strength, but the weight is excessive and fuel efficiency decreases

Engineering Contradiction:

Improvespring strengthVSAvoidspring weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The heavy single leaf spring is segmented into multiple thinner individual leaf springs arranged in parallel. This segmentation reduces the weight of each individual component while maintaining the overall load-bearing capacity through the combined structure, achieving weight reduction without sacrificing strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each individual leaf spring in the multi-leaf assembly can have optimized local properties including varying thickness profiles and material characteristics tailored to specific loading conditions. This allows for weight reduction in non-critical areas while maintaining sufficient strength where needed, achieving better weight-to-strength ratio than conventional uniform springs.

Inventive Principle:

Principle #3Local quality

4Reliability

If safety systems are added to prevent axle dislocation in case of spring failure, then the reliability increases, but the device complexity and cost increase

Engineering Contradiction:

Improvesafety against axle dislocationVSAvoidsafety system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The multi-leaf spring assembly inherently provides redundancy and gradual failure characteristics. If one leaf spring fails, the remaining leaves continue to support the load, providing a cushioning effect that prevents sudden axle dislocation. This inherent safety mechanism eliminates the need for additional complex safety systems while maintaining high reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 achieves a significant weight reduction of approximately 30% without increasing spring thickness, allowing for cost-effective and reliable operation, as the vehicle can continue to be driven after a spring breakage without losing steering control.

Implementation Method 1

the suspension systems provided for supporting and damping the relative movement between each axle and the vehicle frame have included single-stage multi-leaf springs

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2809532B1Vehicle suspension comprising light weight leaf spring assembly

Publication Date: 2019.01.02 VOLVO TRUCK CORP

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Figure 2A~2B
Figure 3A~3C

AI summary

The invention relates to a vehicle suspension leaf spring assembly arranged to be mounted in the longitudinal direction of the vehicle on opposite sides thereof. The leaf spring assembly has a first end, which is arranged for pivotal connection to a first bracket on the vehicle; and a second end, which is arranged for connection to a spring shackle on the vehicle. The leaf spring assembly is arranged to be connected to an axle extending transversely of said leaf spring assembly at a position intermediate the first and second ends of said leaf spring assembly. The leaf spring assembly comprises two individual leaf springs arranged side-by-side with a predetermined spacing and extending between said first and second ends.