Elastomeric Shear Spring Suspension for Roll Stability

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Solution Overview

Problem

Existing vehicle suspensions for vocational or heavy haul trucks face issues with ride quality and roll stability due to fixed or variable spring rates, leading to abrupt changes in spring rate and tensile loading that compromises durability and comfort.

Innovation Solution

A vehicle suspension system with shear springs and progressive spring rate load cushions that provide a continuously increasing spring rate without discontinuities, minimizing tensile loading and using a modular design with reduced fasteners to enhance durability and maintain ride quality across varying loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a fixed spring rate is used in single spring rate suspensions, then roll stability is improved, but ride quality deteriorates

Engineering Contradiction:

Improveroll stabilityVSAvoidride quality

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The suspension system transitions from a fixed spring rate to a dynamic, continuously variable spring rate that adapts to loading conditions. The progressive spring rate increases smoothly as load increases, allowing the system to optimize between ride quality and roll stability dynamically rather than being fixed at a single rate.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The spring rate parameter is changed from a constant value to a continuously varying parameter. The elastomeric spring's spring rate changes progressively with compression, providing a smooth transition that eliminates abrupt changes while maintaining both ride quality and roll stability across different operating conditions.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If auxiliary springs are engaged or disengaged as a function of load in variable rate suspensions, then spring rate adaptability is improved, but ride quality deteriorates due to strike-through effect

Engineering Contradiction:

Improvespring rate adaptabilityVSAvoidride quality

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The suspension system eliminates discontinuous spring rate changes by using a single elastomeric spring that provides continuous, smooth spring rate progression. The useful action of spring rate adaptation continues without interruption or abrupt transitions, preventing the strike-through effect that occurs when auxiliary springs engage or disengage.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The invention removes the auxiliary springs and their engagement/disengagement mechanism from the system. By using only a single elastomeric spring with inherently progressive characteristics, the system eliminates the source of abrupt spring rate changes while maintaining adaptability through the elastomer's material properties.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If elastomeric springs undergo tensile loading to achieve variable spring rate, then spring rate variability is improved, but durability deteriorates due to elastomeric breakdown

Engineering Contradiction:

Improvespring rate variabilityVSAvoiddurability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Instead of using tensile loading to achieve variable spring rate (which causes elastomeric breakdown), the invention inverts the approach by using compressive loading. The elastomeric spring is compressed between the load cushion and the frame hanger, which is the appropriate loading mode for elastomers that maintains durability while providing variable spring rate characteristics.

Inventive Principle:

Principle #13The other way round (Inversion)

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 improved ride quality and roll stability without abrupt spring rate changes, reduces tensile loading, and increases durability by using shear springs and progressive load cushions in a modular suspension system.

Implementation Method 1

elastomeric spring vehicle suspensions

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The spring rate for such a suspension can change due to the engagement or disengagement of the auxiliary spring

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

shear springs and progressive spring rate load cushions

Methodology Applied

Scientific EffectShear stress: Shear Stress

Data Source

PatentUS8052166B2Tie-plate and frame hanger of a suspension assembly

Publication Date: 2011.11.08 HENDRICKSON USA LLC

AI summary

An elastomeric spring suspension is described for supporting a longitudinally extending vehicle frame rail above first and second axles forming a tandem axle configuration. The suspension includes a frame hanger assembly mounted to the vehicle frame rail. The frame hanger assembly has two full spring modules, each of which includes two shear springs, a progressive spring rate load cushion having a pyramidal shape with a flattened top surface and a spring mount for mounting the springs. A saddle assembly is connected to the spring mount, and an equalizing beam is connected to the saddle assembly and further connected to the axles. The spring rate for the suspension increases almost linearly as a function of sprung load, resembling a pneumatic suspension. Accordingly, the suspension exhibits excellent ride quality, without sacrificing roll stability.