Magnetic Load Sensor Unit for Electric Brake Systems

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Solution Overview

Problem

Existing load sensor units in electric brake systems face issues with durability under impulsive or oblique loads and are susceptible to temperature-related errors due to their design, which affects the accuracy of load detection.

Innovation Solution

A magnetic load sensor unit is designed with a flange member that deflects under axial load, featuring a magnetic target and sensor arrangement where the magnetic target is fixed to the flange member and the sensor to the support member, allowing relative movement to detect loads based on magnetic field changes, minimizing the impact of temperature and external vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If piezoelectric crystal elements are used to detect loads with minimum displacement, then measurement precision is improved, but reliability deteriorates due to cracking or chipping under impulsive or oblique loads

Engineering Contradiction:
Improveload detection precisionVSAvoiddurability under impulsive or oblique loads
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical contact-based piezoelectric crystal element with a magnetic field-based detection system. A magnetic target is attached to the flange member that deflects under load, and a magnetic sensor detects the change in magnetic field as the flange member deflects. This substitution eliminates the mechanical contact and fragility of piezoelectric crystals while maintaining the ability to detect minute displacements through magnetic field changes.

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

2Reliability

If strain gauge is used on cylindrical metal member, then reliability is improved, but measurement precision deteriorates due to temperature influence on detection

Engineering Contradiction:
ImprovedurabilityVSAvoidload detection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the strain gauge measurement system with a magnetic field-based measurement system. Instead of measuring strain on a metal member that is influenced by temperature, the system uses a magnetic sensor to detect the position of a magnetic target attached to the deflecting flange member. This magnetic field-based approach is not influenced by temperature changes, thereby maintaining measurement precision while preserving reliability.

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

3Measurement precision

If magnetic sensor is fixed to deflecting flange member, then measurement precision is improved, but reliability deteriorates due to exposure to impulsive or oblique loads

Engineering Contradiction:
Improveload detection precisionVSAvoiddurability under impulsive or oblique loads
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent inverts the traditional sensor mounting approach. Instead of fixing the magnetic sensor to the deflecting flange member (which would expose it to damaging loads), the magnetic sensor is fixed to the stationary support member, while the magnetic target is attached to the deflecting flange member. This inversion allows the flange member to deflect freely under load without compromising the magnetic sensor, while the magnetic field changes still accurately reflect the load magnitude.

Inventive Principle:
Principle #13The other way round (Inversion)

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 magnetic load sensor unit provides high durability and accurate detection of axial loads with minimal displacement, resisting impulsive and oblique loads, and is less influenced by temperature changes, ensuring stable and precise measurements.

Implementation Method 1

at least one magnetic target which generates a magnetic field, and at least one magnetic sensor for detecting a magnetic field generated by the magnetic target

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP2741063B1Magnetic load sensor unit
Publication Date: 2019.05.08 NTN CORP
  • EP2741063B1 patent drawingFigure 1~2
  • EP2741063B1 patent drawingFigure 3
  • EP2741063B1 patent drawingFigure 4~5

AI summary

A magnetic load sensor unit is provided which can detect a load with a minute movement of its part, and which is durable and less likely to be influenced by temperature. The sensor unit includes a flange member (1) deflectable when an axial load is applied, a support member (2) supporting the flange member (1), a magnetic target (3) which generates a magnetic field, and a magnetic sensor (4) for detecting the magnetic field generated by the magnetic target (3). The magnetic target (3) and the magnetic sensor (4) are fixed to the flange member (1) and the support member (2), respectively, such that when the flange member (1) is deflected, the magnetic target (3) and the magnetic sensor (4) move relative to each other, whereby magnitude of the load can be detected based on the magnetic field detected by the magnetic sensor (4).