Low-Permeability MR Clutch Drums for Torque Bandwidth

Solution Overview

Problem

Magnetorheological (MR) fluid clutch apparatuses with high-permeability steel drums face challenges in weight, inertia, and momentum, which limit their bandwidth and performance in applications requiring quick reaction times, such as collaborative robotics.

Innovation Solution

The use of low-permeability materials like plastic or aluminum for the drums, with thicknesses ranging from 0.05 mm to 1.00 mm, in a concentric arrangement, reduces inertia and weight, allowing for improved torque transmission and increased bandwidth by varying the magnetic field strength with electromagnets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-permeability steel drums are used in MR fluid clutch apparatuses, then magnetic field transmission is improved, but weight and inertia increase, reducing bandwidth and responsiveness

Engineering Contradiction:

Improvemagnetic field transmissionVSAvoiddrum weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from high-permeability steel to low-permeability materials (plastic, aluminum, or steel with permeability less than 1.0×10^-4 H/m), fundamentally altering the magnetic properties of the drum while maintaining functional performance through alternative magnetic circuit design

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures where the low-permeability drum works in conjunction with electromagnets and MR fluid to achieve the desired magnetic field transmission, combining materials with different magnetic properties to optimize both weight and magnetic performance

Inventive Principle:

Principle #40Composite materials

2Reliability

If high-permeability steel drums are used in MR fluid clutch apparatuses, then magnetic field transmission is improved, but inertia and momentum increase, limiting bandwidth

Engineering Contradiction:

Improvemagnetic field transmissionVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent changes the material parameter from high-permeability steel to low-permeability materials (plastic, aluminum, or steel with permeability less than 1.0×10^-4 H/m), fundamentally altering the magnetic properties of the drum while maintaining functional performance through alternative magnetic circuit design

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional mechanical magnetic circuit (relying on high-permeability steel) with an electromagnetic system using electromagnets and MR fluid, substituting mechanical magnetic transmission with a controllable electromagnetic field approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If thick steel drums are used to ensure sufficient magnetic permeability, then magnetic field transmission is improved, but manufacturing cost increases

Engineering Contradiction:

Improvemagnetic field transmissionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from high-permeability steel to low-permeability materials (plastic, aluminum, or steel with permeability less than 1.0×10^-4 H/m), fundamentally altering the magnetic properties of the drum while maintaining functional performance through alternative magnetic circuit design

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies magnetic permeability enhancement locally at the shear surfaces through thin coatings (0.05 mm to 1.00 mm thickness) rather than requiring the entire drum to be made of thick high-permeability material, optimizing both cost and performance

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

This configuration results in a lighter MR fluid clutch apparatus with enhanced bandwidth and durability, reduced slippage, and increased torque to inertia ratio, improving controllability and performance in applications requiring high responsiveness.

Implementation Method 1

at least one electromagnet configured to deliver a magnetic field through the magnetorheological fluid

Methodology Applied

Scientific EffectElectromagnetic field generation: Electromagnet

Implementation Method 2

magnetorheological fluid in the at least one annular space, the magnetorheological fluid configured to generate a variable amount of torque transmission between the input rotor and output rotor when subjected to a magnetic field

Methodology Applied

Scientific EffectMagnetorheological effect: Magnetorheological Fluid

Data Source

PatentUS11499594B2Magnetorheological fluid clutch apparatus with low permeability drums

Publication Date: 2022.11.15 EXONETIK INC

AI summary

A magnetorheological fluid clutch apparatus comprises an input(s) having an input shear surface(s). An output(s) is rotatably mounted about the input for rotating about a common axis with the input, the output(s) having output shear surface(s), the input shear surface and the output shear surface separated annular space(s), with magnetorheological fluid, configured to generate a variable amount of torque transmission between the sets of input rotor and output rotor when subjected to a magnetic field. An electromagnet(s) delivers a magnetic field through the magnetorheological fluid, the electromagnet configured to vary the strength of the magnetic field, whereby actuation of the electromagnet results in torque transmission from the input to the output. A member(s) defining at least one of the shear surfaces is made of a low-permeability material.