Contactless Disc Brake Wear Sensor Using Magnetic Nesting

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Solution Overview

Problem

Existing disc brake monitoring devices face issues with limited service life, complex installation, high assembly costs, and the need for additional components and tools, which complicate wear measurement and adjustment path detection.

Innovation Solution

A contactless monitoring device integrated into the disc brake's adjustment device, using a prestressed measuring element and sensor unit to detect relative positions without mechanical contact, allowing for easy installation, retrofitting, and reduced wear, with a compact design that minimizes additional space requirements and eliminates the need for special tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a potentiometer is used to detect the movement of the pin in the wear monitoring device, then the wear and brake stroke can be measured, but the service life of the monitoring device is limited due to the potentiometer's limited durability

Engineering Contradiction:
Improvewear detection accuracyVSAvoidservice life of monitoring device
Core Design Contradiction:
Measurement precisionVSDuration of action of moving object

Solution Approach 1:

The patent replaces the mechanical potentiometer with a magnetic field-based sensor system. A magnet is mounted on the pressure spindle, and a Hall sensor or reed switch in the sensor unit detects its position contactlessly. This substitution eliminates mechanical contact and wear, significantly extending the service life while maintaining measurement precision for wear and brake stroke detection.

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

2Measurement precision

If a gear wheel and reduction gear are used to transmit rotation from the pressure spindle to the hollow shaft, then the rotation can be detected, but the device complexity increases due to the large number of components

Engineering Contradiction:
Improveadjustment path detectionVSAvoidnumber of components
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent eliminates the mechanical gear wheel and reduction gear by using a magnetic field-based detection system. The magnet attached to the pressure spindle directly interacts with the Hall sensor or reed switch, allowing rotation and position detection without any intermediate mechanical transmission components. This dramatically simplifies the device structure while maintaining detection accuracy.

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

Solution Approach 2:

The patent extracts and removes the complex mechanical transmission components (gear wheel, reduction gear) from the system, retaining only the essential detection function through the magnetic sensor approach. This extraction eliminates unnecessary components and simplifies the overall device structure.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If the monitoring device is provided as an external device placed on the brake caliper housing, then it can be installed, but additional installation space is required on the brake caliper

Engineering Contradiction:
Improveinstallation flexibilityVSAvoidinstallation space on brake caliper
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent integrates the sensor unit into the pressure spindle assembly, with the sensor unit positioned inside or on the pressure spindle housing. The magnet is mounted on the pressure spindle itself, and the sensor unit is nested within the existing brake caliper structure. This nesting approach eliminates the need for additional external mounting space while maintaining full functionality.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent merges the monitoring device components with the existing brake caliper structure. The sensor unit is integrated into the pressure spindle assembly, and the magnet is combined with the pressure spindle. This merging eliminates the need for separate external mounting and reduces the overall space requirement on the brake caliper.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of operation

If a reset tool is required to turn the pressure spindle back to its original starting position, then the adjustment device can be reset, but resetting becomes laborious and requires special tools

Engineering Contradiction:
Improvereset functionalityVSAvoidneed for special tools
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent enables the pressure spindle to be reset using standard tools or even manual operation. The pressure spindle is designed with a reset mechanism that allows it to be turned back to the starting position without requiring specialized reset tools. The magnetic sensor system continuously monitors the position, providing feedback that confirms when the reset is complete, making the process self-service oriented and eliminating the need for special tools.

Inventive Principle:
Principle #25Self-service

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 monitoring device with a long service life, simplified installation and maintenance, reduced assembly effort, and accurate detection of brake pad wear and adjustment paths, enhancing the reliability and efficiency of disc brake operation.

Implementation Method 1

The sensor unit has a Hall sensor or a reed switch, the magnet is positioned on the pressure spindle in such a way that, when the pressure spindle is adjusted, the magnet moves along a measuring direction parallel to the adjustment path

Methodology Applied
Scientific EffectHall effect: Hall Effect

Implementation Method 2

The sensor unit has a Hall sensor or a reed switch, the magnet is positioned on the pressure spindle in such a way that, when the pressure spindle is adjusted, the magnet moves along a measuring direction parallel to the adjustment path

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentEP3362699B1Monitoring device for a disk brake of a motor vehicle
Publication Date: 2020.09.09 ZF CV SYST EURO BV
  • EP3362699B1 patent drawingFigure 1~2
  • EP3362699B1 patent drawingFigure 2a~2b
  • EP3362699B1 patent drawingFigure 3~4

AI summary

The invention relates to a monitoring device (12) for a disk brake (1), said monitoring device at least comprising: a sensor unit (14) for attachment to a brake caliper (2) of a disk brake (1) and a measuring element (13), wherein the sensor unit (14) is configured to detect a relative position of the measuring element (13), said measuring element being movable relative to the sensor unit (14), wherein the sensor unit (14) and the measuring element (13) are spaced apart from one another for forming a contact-less monitoring device (12). According to the invention, a biasing element (17) is arranged between the measuring element (13) and the sensor unit (14) for biasing the measuring element (13) against a pressure spindle (7) of the disk brake (1).