Leaf Spring Curvature for Progressive Force Absorption

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Solution Overview

Problem

Existing leaf spring designs for vehicles suffer from abrupt transition in spring characteristics, leading to adverse driving characteristics and increased weight, which affects energy consumption and payload capacity, while also failing to effectively cushion horizontal force components during braking.

Innovation Solution

A one-piece leaf spring with a unique geometry featuring first and second curved areas with opposite directions of curvature, allowing it to progressively change length with load and cushion both vertical and horizontal forces without the need for additional components like shackles, enabling a stationary connection to the vehicle frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a two-part leaf spring design is used to achieve progressive spring characteristic, then the spring can absorb low forces and provide supporting effect, but the transition is abrupt causing negative driving characteristics and the weight increases

Engineering Contradiction:
Improvespring characteristicVSAvoidspring weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The leaf spring is divided into multiple curved areas (first curved area, second curved area, third curved area) with different curvature directions and magnitudes, allowing each segment to contribute differently to the spring characteristic and enable progressive force absorption without abrupt transitions

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The leaf spring features asymmetric geometry with curved areas having opposite directions of curvature relative to the central axis, creating a progressive spring characteristic that smoothly transitions between different load conditions while maintaining a one-piece construction

Inventive Principle:
Principle #4Asymmetry

2Adaptability or versatility

If a one-piece leaf spring with progressive characteristic curve is used, then the spring can cushion vertical force components, but horizontal force components cannot be cushioned increasing breakage risk

Engineering Contradiction:
Improvespring characteristicVSAvoidspring breakage risk
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The leaf spring incorporates multiple curved areas with varying curvature directions (first direction, second direction, third direction) that allow the spring to deflect in multiple directions, enabling it to cushion both vertical force components during normal operation and horizontal force components during braking

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The single leaf spring structure performs multiple functions: it cushions vertical forces during normal vehicle operation, absorbs horizontal forces during braking, and provides progressive spring characteristic, eliminating the need for separate components like shackles

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If shackles are used to connect the spring to counteract length change during braking, then horizontal force components can be countered, but additional weight and components are required

Engineering Contradiction:
Improvehorizontal force resistanceVSAvoidconnection components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The leaf spring's own geometry with multiple curved areas enables it to counteract length changes during braking without requiring external shackles or additional connection components, simplifying the suspension system while maintaining reliability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The leaf spring uses its own structural geometry (curved areas with opposite curvature directions) to automatically counteract horizontal force components during braking, eliminating the need for separate counteracting mechanisms

Inventive Principle:
Principle #25Self-service

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 provides a smooth, progressive spring characteristic that enhances driving performance, reduces the risk of spring breakage, minimizes weight, and eliminates the need for additional components, resulting in improved energy efficiency and reduced overall vehicle weight.

Implementation Method 1

A one-piece leaf spring with a unique geometry featuring first and second curved areas with opposite directions of curvature, allowing it to progressively change length with load and cushion both vertical and horizontal forces

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3237775B1Spring for a vehicle
Publication Date: 2022.12.07 HENDRICKSON COMML VEHICLE SYST EURO GMBH
  • EP3237775B1 patent drawingFigure 1~3
  • EP3237775B1 patent drawingFigure 4~5b
  • EP3237775B1 patent drawingFigure 5c~6c

AI summary

A spring, in particular, a leaf spring (1), to be used in connection with a vehicle has a central section (2), wherein the central section (2) has a center axis (3), as well as two edge sections (4), wherein the edge sections (4) each have an end section (5). In an unloaded state, at least one edge section (4) adjacent to the central section (2) has a first curved section (6) with a first curvature direction and a first vertex (7), wherein the first vertex (7) is located on one side of the center axis (3). In the direction of its end section (5), this edge section (4) has a second curved section (8) with a second curvature direction and a second vertex (9), wherein the second curvature direction is opposed to the first curvature direction, and wherein the second vertex (9) is located on the side of the center axis (3) opposite the first vertex (7).