Single-Piece Leaf Spring With Variable Spring Rate

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Solution Overview

Problem

Existing leaf spring designs face issues with increased weight, carbon emissions, vibrations, chassis fatigue, and material strength losses due to multiple layers and auxiliary components, which complicate the achievement of varying spring rates without incurring additional costs or material deformations.

Innovation Solution

A single-piece leaf spring design featuring a long spring and short spring with specific geometric and material properties that interact to change spring rate independently, eliminating the need for auxiliary layers and external supports, allowing for multiple spring rates without weight or cost penalties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If auxiliary layers are added to increase spring rate, then the spring rate increases, but the weight of the leaf spring increases

Engineering Contradiction:

Improvespring rateVSAvoidweight of leaf spring

Core Design Contradiction:

ForceVSWeight of moving object

Solution Approach 1:

The leaf spring is divided into two functional regions: a first region with higher rigidity and a second region with lower rigidity. This segmentation allows different parts of the spring to have different spring rates, enabling the spring rate to increase with displacement without adding auxiliary layers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the leaf spring are designed with different local properties - the first region has higher rigidity while the second region has lower rigidity. This local quality variation allows the spring to provide multiple spring rates through vertical displacement alone, eliminating the need for additional layers.

Inventive Principle:

Principle #3Local quality

2Force

If auxiliary layers are added to increase spring rate, then the spring rate increases, but the overall weight of the vehicle increases

Engineering Contradiction:

Improvespring rateVSAvoidoverall weight of vehicle

Core Design Contradiction:

ForceVSWeight of stationary object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

3Force

If multiple layers are used to achieve varying spring rates, then the spring rate varies with displacement, but vibrations are generated during driving

Engineering Contradiction:

Improvespring rateVSAvoidvibrations

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

4Force

If multiple layers are used to achieve varying spring rates, then the spring rate varies with displacement, but chassis fatigue occurs

Engineering Contradiction:

Improvespring rateVSAvoidchassis fatigue

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

5Force

If auxiliary layers and fasteners are used to assemble the leaf spring, then the spring rate increases, but material strength losses occur

Engineering Contradiction:

Improvespring rateVSAvoidmaterial strength

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The leaf spring is manufactured as a single integrated piece with two different rigidity regions, eliminating the need for separate auxiliary layers and fasteners. This merging of functions into a single component avoids the strength losses that would occur at assembly interfaces.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

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

The design reduces material usage and weight, decreases carbon emissions, and extends the lifespan of leaf springs by avoiding material fatigue and deformation, while maintaining performance through geometric and material adjustments without external supports.

Implementation Method 1

a long spring (1) and a short spring (2) which are made from the same or different materials and have the same or different geometric properties

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS20230313857A1Leaf spring that provides multiple spring rates

Publication Date: 2023.10.05 OLGUN CELIK SANAYI & TICARET ANONIM SIRKETI

AI summary

A leaf spring structure is designed as a single piece to be able to change the spring rates of leaf springs under a load independently from the manufacturing material. The operating mechanism of the leaf spring allows for increasing the spring rates by deactivating the short spring, which remains between the point A and the point B, as a result of the interaction between the short spring and the long spring after a certain amount of vertical displacement in the leaf spring.