Friction Material with Diatomaceous Earth for Wet Stability

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Solution Overview

Problem

Existing friction materials for applications like brake and clutch systems face challenges in achieving excellent friction stability, wear-resistance, noise-resistance, pressure-resistance, and temperature-resistance, especially when submerged in lubricants, due to insufficient structural strength and porosity.

Innovation Solution

A friction material comprising a resin-impregnated fibrous base material with a specific composition of aramid fibers, polyacrylonitrile-based carbon fibers, and diatomaceous earth, where the fibrous base material includes a higher amount of diatomaceous earth than aramid or carbon fibers, and is free from activated carbon, providing enhanced porosity, strength, and lubricant compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional friction materials are used in wet applications, then lubrication is provided, but friction stability and wear-resistance deteriorate due to insufficient structural strength and porosity

Engineering Contradiction:
Improvefriction stabilityVSAvoidstructural strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The friction material uses a composite fibrous base material combining aramid fibers (15-35 parts), polyacrylonitrile-based carbon fibers (5-25 parts), and diatomaceous earth (45-65 parts) to achieve both structural strength and porosity. This composite structure provides the necessary mechanical strength while maintaining lubricant retention capability for stable friction performance in wet applications.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The friction material incorporates diatomaceous earth as a porous filler material that retains lubricant within the friction material structure. The porous structure allows the material to absorb and hold lubricant, ensuring consistent friction performance and preventing fade during operation while maintaining adequate structural integrity.

Inventive Principle:
Principle #31Porous materials

2Reliability

If diatomaceous earth content is increased to improve porosity and lubricant retention, then friction stability improves, but manufacturing complexity increases due to precise composition requirements

Engineering Contradiction:
Improvefriction stabilityVSAvoidcomposition specification complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention specifies precise parameter ranges for each component: aramid fibers (15-35 parts), polyacrylonitrile-based carbon fibers (5-25 parts), and diatomaceous earth (45-65 parts) based on 100 parts of fibrous base material. These defined parameter ranges optimize the balance between porosity, structural strength, and friction stability while providing clear manufacturing guidelines.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If activated carbon is used in friction material, then friction performance is enhanced, but noise-resistance deteriorates

Engineering Contradiction:
Improvefriction performanceVSAvoidnoise
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention explicitly excludes activated carbon from the friction material composition to eliminate the noise problem associated with its use. Instead, the formulation relies on aramid fibers, polyacrylonitrile-based carbon fibers, and diatomaceous earth to achieve the desired friction performance without the harmful noise effect produced by activated carbon in wet applications.

Inventive Principle:
Principle #2Taking out (Extraction)

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 friction material exhibits improved friction stability, noise-resistance, and wear-resistance, maintaining a positive coefficient of friction slope across varying speeds, reducing shuddering and noise, and maintaining structural integrity under pressure and temperature conditions.

Implementation Method 1

the fibrous base material has a single ply and includes a plurality of aramid fibers present in a first amount, a plurality of polyacrylonitrile-based carbon fibers present in a second amount that is less than the first amount, and diatomaceous earth present in a third amount that is greater than the first amount

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP2598768B1Friction member and friction material thereof
Publication Date: 2018.12.26 EATON CORP
  • EP2598768B1 patent drawingFigure 1~2

AI summary

A friction material (18) includes a resin and a fibrous base material impregnated with the resin. The fibrous base material has a single ply, and includes a plurality of aramid fibers present in a first amount, a plurality of polyacrylonitrile-based carbon fibers present in a second amount that is less than the first amount, and diatomaceous earth present in a third amount that is greater than the first amount. The fibrous base material is substantially free from activated carbon. A friction member for operatively contacting a lubricated surface (12) includes a substrate (16) and a friction material (18). The friction material (18) defines a first surface (20) bonded to the substrate (16) and a second surface (22) configured for operatively contacting the lubricated surface (12).