Inductive Wear Sensor for Disc Brake Pad Monitoring

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing brake pad wear detection systems for motor vehicles, particularly commercial vehicles, are limited in their ability to continuously monitor wear and are not suitable for both floating-caliper and fixed-caliper disc brakes, as they can only indicate when a brake pad has reached a predetermined state of wear rather than providing real-time or precise measurements.

Innovation Solution

A disc brake system equipped with an inductive planar coil wear sensor attached to the pad carrier plate, which allows for continuous wear detection by measuring the distance between the pad carrier plate and the brake disc, and is compatible with both floating-caliper and fixed-caliper disc brakes, enabling separate monitoring of each brake pad and detecting misalignments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conductors or conductor loops are embedded in the friction lining to detect wear, then wear detection is possible, but only discrete wear state indication is achieved rather than continuous monitoring

Engineering Contradiction:
Improvewear detection precisionVSAvoidcontinuous wear information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent replaces mechanical contact-based wear detection (conductors touching the disc) with an inductive sensing system. The inductive pick-up with coil and coil core detects the axial position of the actuating element without mechanical contact, enabling continuous measurement of brake pad thickness and wear state, thus transforming discrete mechanical detection into continuous non-contact sensing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an inductive pick-up as an intermediary sensing device between the brake pad assembly and the evaluation system. This pick-up converts the physical displacement of the actuating element into an electrical signal that can be continuously evaluated, serving as a mediator that enables continuous wear information extraction without direct mechanical contact or embedding conductors in the friction lining.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a floating caliper displacement path measurement is used to determine brake lining wear, then wear detection is achieved, but only total wear can be detected and not separate pad wear

Engineering Contradiction:
Improvewear detection capabilityVSAvoidseparate pad wear information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent applies segmentation by equipping each brake pad with its own inductive pick-up sensor. This allows independent measurement of the axial position for each pad, enabling separate detection of wear for individual brake pads rather than measuring only the total displacement of the floating caliper. Each sensor provides independent data about its respective pad's wear state.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If wear sensors are installed in the brake cylinder or on the brake housing, then wear detection is possible, but the system is not suitable for both floating-caliper and fixed-caliper disc brakes

Engineering Contradiction:
Improvebrake system compatibilityVSAvoidwear detection reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent achieves universality by integrating the inductive pick-up sensor directly into the brake pad assembly itself, rather than mounting it on the caliper or housing. This placement allows the same sensor design to function in both floating-caliper and fixed-caliper disc brake systems, as it is attached to the component (brake pad) that is common to both brake types, thereby enabling a single solution to serve multiple brake system configurations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Productivity

If traditional wear detection sensors are used, then wear indication is possible, but continuous wear detection and high-resolution monitoring cannot be achieved

Engineering Contradiction:
Improvewear monitoring capabilityVSAvoidwear measurement resolution
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces traditional mechanical contact-based wear sensors with an inductive sensing system. The inductive pick-up detects the axial position of the actuating element through electromagnetic induction, providing continuous, high-resolution measurement of brake pad thickness without mechanical contact. This substitution enables precise, continuous monitoring of wear progression rather than discrete wear state indication.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables continuous, high-resolution monitoring of brake pad wear and stroke during braking, allowing for timely detection of pad wear and misalignments, with the added advantage of temperature stability and compact design that does not occupy additional space in the pad shafts.

Implementation Method 1

the wear sensor is Lining carrier plate attached inductive planar coil designed to determine the distance from the brake disc

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2867557B1Disc brake of a motor vehicle
Publication Date: 2018.04.18 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP2867557B1 patent drawingFigure 1
  • EP2867557B1 patent drawingFigure 2
  • EP2867557B1 patent drawingFigure 3

AI summary

A disc brake of a motor vehicle has a brake calliper extending over a brake disc, at least one brake lining provided with a lining support plate (2) and a friction lining attached thereto, a device for detecting brake lining wear having at least one wear sensor (3), wherein the wear sensor (3) is designed as an inductive distance sensor attached to the lining support plate (2) to determine the distance between the lining support plate (2) and the brake disc, and is connected to an evaluation circuit (5).