Disc Brake Running Clearance Calculation via Piston Axial Displacement

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Solution Overview

Problem

Existing disc brake systems lack precise monitoring of running clearance, which can lead to unsafe operating conditions due to insufficient or excessive clearance, affecting brake performance and wear, and are not effectively detected until a critical event occurs.

Innovation Solution

A method to calculate the total running clearance by detecting the axial movement of a piston assembly component during braking, using sensors to determine the displacement before brake pads contact the rotor, and applying a knee point detection algorithm to analyze input force and pressure changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional manual adjuster mechanisms with CWS are used to monitor brake wear, then the system can provide an estimate of total wear, but the running clearance measurement is imprecise and requires the vehicle to be stationary for manual measurement

Engineering Contradiction:
Improverunning clearance measurement precisionVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical measurement methods with an automated sensor-based system. Sensors detect the position of brake pads and rotor to automatically calculate running clearance, eliminating the need for manual measurement while the vehicle is stationary. This substitution of mechanical measurement with automated sensing directly improves measurement precision while maintaining system simplicity.

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

2Reliability

If the running clearance is not monitored precisely in real-time, then the system operates with simpler monitoring, but brake performance issues are not detected until critical events occur

Engineering Contradiction:
Improvebrake performance reliabilityVSAvoidclearance monitoring automation
Core Design Contradiction:
ReliabilityVSExtent of automation

Solution Approach 1:

The patent implements a feedback mechanism where sensors continuously monitor brake pad position and rotor position, automatically calculate running clearance, and provide real-time feedback on brake health status. This feedback loop enables early detection of clearance issues before they become critical, improving reliability while using moderate automation through automated calculation algorithms.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of running clearance issues before they develop into critical problems. By continuously monitoring and calculating clearance in advance, the system can alert operators to potential issues before they affect brake performance, preventing critical events rather than reacting to them.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If the running clearance is too high, then the brake assembly structure allows greater tolerance, but brake performance deteriorates due to insufficient clamping force

Engineering Contradiction:
Improveclearance tolerance stabilityVSAvoidbrake performance reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The feedback mechanism continuously monitors running clearance and can alert operators when clearance exceeds acceptable thresholds. This real-time feedback enables maintenance personnel to adjust clearance before it becomes too high, maintaining both structural tolerance stability and brake performance reliability through proactive adjustment rather than reactive repair.

Inventive Principle:
Principle #23Feedback

4Reliability

If the running clearance is too low, then the brake pads maintain better contact with the rotor, but excessive wear and overheating occur

Engineering Contradiction:
Improvebrake contact reliabilityVSAvoidexcessive wear and overheating
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The continuous monitoring system detects when running clearance becomes too low and can alert operators to increase the clearance through manual adjustment. This feedback prevents excessive wear and overheating by maintaining clearance within the optimal range, balancing reliable brake contact with prevention of harmful thermal and mechanical effects.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4306373B1Method and apparatus for calculating the running clearance of a disc brake
Publication Date: 2025.11.12 MERITOR HEAVY VEHICLE BRAKING SYSTEMS (UK) LIMITED
  • EP4306373B1 patent drawingFigure 1
  • EP4306373B1 patent drawingFigure 2A
  • EP4306373B1 patent drawingFigure 2B

AI summary

A method and apparatus for calculating the total running clearance of a disc brake having inboard and outboard brake pads arranged to contact a rotor during a braking operation, wherein a piston assembly is configured to actuate the inboard brake pad of the disc brake. The method includes detecting the axial movement of a component of the piston assembly to provide data indicating the displacement of the component of the piston assembly during the braking operation; and determining the amount of displacement of the component of the piston assembly that occurs before the inboard brake pad and outboard brake pad are both contacting the rotor to provide a calculated total running clearance.