Tone Ring Attachment Using Dart Projections

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Solution Overview

Problem

Existing antilock braking systems for heavy-duty vehicles face issues with corrosion due to road salts and de-icing chemicals, leading to rust-jacking and increased maintenance costs, particularly with the use of ferrous metal roll pins and powdered metal tone rings that are costly and difficult to produce.

Innovation Solution

A tone ring and attachment structure using tubular steel with dart projections and a corrosion-resistant coating, such as zinc-rich material, to securely mount the tone ring to the disc brake rotor, reducing corrosion risks and simplifying the mounting process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If ferrous metal roll pins are used to secure the tone ring to the rotor, then the tone ring is securely retained, but corrosion occurs leading to rust-jacking and increased maintenance costs

Engineering Contradiction:

Improveretention strengthVSAvoidcorrosion

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the durable but corrosion-prone ferrous roll pin with a disposable plastic retaining clip. The plastic clip is designed to be installed once and then discarded when the brake rotor is removed, eliminating the corrosion problem entirely. This applies the principle of using a less durable material (plastic vs metal) that avoids the specific harmful effect of corrosion while maintaining sufficient retention strength during service life.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the material parameter from ferrous metal to plastic, fundamentally altering the chemical properties to eliminate corrosion susceptibility. This material substitution changes the retention mechanism from metal-to-metal friction to plastic engagement, which does not corrode and therefore prevents rust-jacking of the tone ring.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a powdered metal tone ring with integrally formed bosses, tabs and dart projections is used, then the tone ring is securely mounted, but the manufacturing cost increases and lead time extends

Engineering Contradiction:

Improvemounting securityVSAvoidmanufacturing cost and lead time

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent divides the tone ring assembly into separate components: the tone ring itself and a separate plastic retaining clip. This segmentation allows the tone ring to be manufactured using traditional, cost-effective methods while the retaining clip is produced separately through injection molding. The separation eliminates the need for complex integral forming operations and reduces tooling costs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a plastic retaining clip as an intermediary component between the tone ring and the rotor lug. This clip serves as a mediator that provides the retention function without requiring the tone ring itself to have complex integrally formed features. The intermediary clip simplifies the tone ring manufacturing while maintaining mounting security.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If road spray containing salt and chemicals is allowed to enter spaces between the tone ring and rotor, then capillary action pumps chemicals into spaces, but corrosion cells form causing rust-jacking

Engineering Contradiction:

Improvenormal operationVSAvoidcorrosion cells

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent addresses the harmful effect of road spray by using a plastic retaining clip that does not corrode. While the spray still enters the space between tone ring and rotor, the plastic material converts the potential harm (corrosion) into a benign situation (no corrosion). The plastic may degrade over time but does not create corrosion cells or rust-jacking forces.

Inventive Principle:

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

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 provides a cost-effective, quick-to-produce tone ring attachment that minimizes corrosion damage, reduces vehicle downtime, and eliminates the need for metal roll pins, enhancing the reliability and efficiency of the antilock braking system.

Implementation Method 1

A tone ring and attachment structure using tubular steel with dart projections and a corrosion-resistant coating, such as zinc-rich material

Methodology Applied

Scientific EffectCorrosion resistance: Oxidation

Data Source

PatentUS11022192B2Tone ring and attachment structure

Publication Date: 2021.06.01 HENDRICKSON USA LLC

AI summary

A tone ring attachment for a disc brake rotor. The disc brake rotor has a disc portion that includes a plurality of circumferentially-spaced lugs. Each one of the lugs has a groove. A discrete tone ring body has a plurality of bosses. Each one of the bosses is receivable in a respective one of the grooves in the lugs. A dart projection extends from at least one of the bosses. The dart projection engages a respective one of the lugs to inhibit relative axial movement and relative rotational movement in at least one direction between the tone ring and the disc brake rotor. A tab is formed on at least one of the bosses. The tab is engageable with a portion of the lug to inhibit relative rotational movement in a second direction opposite the first direction between the tone ring and disc brake rotor.