Adjustable Torsion Spring Using Variable Beam Bending Length

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Solution Overview

Problem

Torsion springs used in vehicle suspensions have fixed and nearly linear spring rates, unable to provide adjustable or customizable non-linear stiffness, including negative stiffness, which limits their application in dynamic systems requiring variable stiffness.

Innovation Solution

A rotational spring design with adjustable stiffness, featuring a base and rotatable section with interdigitated beams, where the relative distance between the base and rotatable section can be adjusted to change the effective bending length of the beams, allowing for customizable non-linear spring rates and regions of negative stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional wound wire or coiled ribbon torsion springs are used, then the spring rate is constant and nearly linear, but the spring rate cannot be adjusted or customized to provide non-linear or negative stiffness

Engineering Contradiction:

Improveadjustability of spring rateVSAvoidstructural complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The torsion spring is divided into multiple discrete beams arranged in a parallel configuration. Each beam can be independently designed with specific geometric properties, allowing the overall spring rate to be adjusted by modifying individual beam characteristics rather than redesigning the entire spring structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs beams with variable cross-sectional dimensions along their length, creating non-uniform geometry that enables non-linear spring rate characteristics. The beams transition from uniform cross-section to tapered or curved profiles, allowing the stiffness to vary dynamically with deflection.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If torsion springs with fixed spring rates are used, then the structure is simple, but the spring cannot adapt to changing environmental dynamics or payload requirements

Engineering Contradiction:

Improvecustomizability of non-linear spring rateVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Different portions of the beam cross-section are designed with varying properties. The beams feature non-uniform thickness and width distributions along their length, creating localized stiffness variations that produce non-linear spring rate characteristics without requiring complex assembly procedures.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent achieves customizable spring rates by varying geometric parameters of the beams including cross-sectional dimensions, length, and curvature. By adjusting these parameters during manufacturing, the spring rate can be tailored to specific applications without changing the fundamental structure or material.

Inventive Principle:

Principle #35Parameter changes

3Force

If the relative distance between base and rotatable section is adjusted to change effective bending length, then the shear stiffness is adjustable, but the device requires additional adjustment mechanisms

Engineering Contradiction:

Improveshear stiffnessVSAvoidadjustment mechanism complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The adjustment mechanism is integrated into the existing spring structure itself. The base and rotatable section are connected through the beam arrangement, allowing the effective bending length to be modified by relative movement between these components without requiring external adjustment devices.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The same beam structure that provides the torsional spring function also serves as the adjustment mechanism. By changing the engagement position or relative distance between the base and rotatable section, both the spring rate adjustment and the structural integrity are maintained through the unified beam design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables adjustable and customizable torsional stiffness, enhancing dynamic systems by allowing for in-place adjustments without reattachment, suitable for systems with changing environmental dynamics or payload, and providing non-linear torsional isolators.

Implementation Method 1

at least one beam arranged about an axis extending between an input tuning port and an output port... change an effective bending length of the at least one beam so as to change a shear stiffness

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11460085B1Torsion springs with changeable stiffness

Publication Date: 2022.10.04 HRL LAB

AI summary

In at least one embodiment, a rotational spring is provided with adjustable stiffness and includes at least one beam arranged about an axis between an input tuning port and an output port, wherein the input tuning port is configured to change an effective bending length of at least one beam so as to change a shear stiffness with respect to the input tuning port and the output port.