Quaternary Ammonium Coating for Wet Friction Material Glazing

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Solution Overview

Problem

Wet friction materials in torque converters and motor vehicle transmissions face glazing issues due to thermal degradation at high temperatures, leading to poor friction behavior and decreased porosity, which existing paper-based materials fail to address effectively.

Innovation Solution

A method involving a quaternary ammonium salt (QAS) containing coating on the outer surface of the friction material, combined with a base binder and filler particles, is applied to prevent glazing by enhancing friction characteristics and maintaining surface cleanliness through detergency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If paper-based friction material is used in wet-type friction clutches, then the material can operate in oil submerged environment, but it suffers from glazing issues due to thermal degradation at high temperatures leading to poor friction behavior

Engineering Contradiction:

Improvefriction behaviorVSAvoidglazing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a quaternary ammonium salt (QAS) containing coating to the outer surface of the friction material base. This coating changes the surface properties of the friction material, providing detergency that prevents thermal degradation and glazing at high temperatures, thereby maintaining reliable friction behavior.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite structure by coating the paper-based friction material base with a QAS-containing solution that includes binder and filler particles. This composite material combines the oil-submerged environment compatibility of paper-based material with the high-temperature resistance and anti-glazing properties of the QAS coating.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional friction material is used, then manufacturing is simple, but porosity decreases due to thermal degradation leading to reduced friction performance

Engineering Contradiction:

Improvemanufacturing processVSAvoidfriction performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The QAS coating modifies the surface parameters of the friction material to resist thermal degradation. The coating maintains appropriate porosity and surface characteristics even at high temperatures, ensuring consistent friction performance without complicating the manufacturing process.

Inventive Principle:

Principle #35Parameter changes

3Power

If friction material operates at high temperatures, then torque transmission is effective, but thermal degradation occurs leading to residue deposition and glazing

Engineering Contradiction:

Improvetorque transmissionVSAvoidresidue deposition

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The QAS coating converts the harmful effect of high-temperature operation into a beneficial outcome. The detergent properties of the QAS coating prevent thermal degradation and residue deposition, allowing the friction material to operate effectively at high temperatures without glazing, thereby maintaining torque transmission capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If the outer surface of friction material is coated with QAS containing solution, then glazing is prevented and friction performance is maintained, but additional manufacturing steps are required

Engineering Contradiction:

Improvefriction performanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The QAS containing solution is applied to the outer surface of the friction material base during the manufacturing process, before the material is assembled into the clutch. This preliminary action ensures the coating is properly applied and dried, integrating the anti-glazing protection into the manufacturing workflow without requiring separate post-assembly steps.

Inventive Principle:

Principle #10Preliminary action

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 QAS coating effectively prevents glazing, maintains friction performance, and improves the durability of the friction material by reducing porosity and residue deposition, thereby enhancing the overall efficiency of the friction clutch system.

Implementation Method 1

maintains surface cleanliness through detergency

Methodology Applied

Scientific EffectDetergency:

Data Source

PatentUS11333214B2Wet friction material with quaternary ammonium salts

Publication Date: 2022.05.17 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

A method of making a wet friction material includes joining filler particles and fibers together and forming a base; coating an outer surface of the base with a quaternary ammonium salt containing solution; and drying the quaternary ammonium salt containing solution to form a quaternary ammonium salt containing coating on the outer surface of the base.