Axial Flux Torque Sensor Design for Compact Steering Systems

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Solution Overview

Problem

Conventional torque angle sensors are bulky and oversized due to the radial magnetic flux design, which affects their axial direction and efficiency in measuring torque angles across torsion bars in automotive steering systems.

Innovation Solution

The design incorporates a ring magnet with axial magnetic flux, surrounded by first and second stators with teeth, and collectors that are magnetically coupled to magnetic sensing elements, allowing for efficient detection of magnetic flux changes corresponding to torque angles through a torsion bar.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a radial magnet design with two stators and teeth is used, then the sensor can detect magnetic flux changes, but the sensor becomes bulky and oversized in the axial direction

Engineering Contradiction:
Improvetorque angle measurementVSAvoidaxial length
Core Design Contradiction:
Measurement precisionVSLength of stationary object

Solution Approach 1:

The patent inverts the conventional radial magnet design by using an axial magnet instead. The single magnet is positioned such that its axial flux interacts with the stator teeth, eliminating the need for two stators and reducing the axial length of the sensor while maintaining measurement capability

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

Solution Approach 2:

The patent extracts and eliminates unnecessary components from the conventional design. By removing one of the two stators and the radial magnet structure, the design simplifies the sensor construction while retaining the essential function of detecting magnetic flux changes for torque angle measurement

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If a radial magnet with two stators is used, then torque angle can be measured, but the device complexity increases

Engineering Contradiction:
Improvetorque angle measurementVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes redundant components (one stator and the radial magnet structure) from the conventional design, simplifying the overall device structure while maintaining the essential measurement function through the axial magnet configuration

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the functions of the magnet and stator assembly into a more integrated configuration. The axial magnet works in conjunction with a single stator with teeth, combining the magnetic flux generation and detection functions in a more compact and simpler arrangement

Inventive Principle:
Principle #5Merging (Combining)

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 configuration reduces the bulkiness and enhances the sensitivity of torque angle measurement, enabling precise detection of angular displacement and torque exertion with improved axial alignment and reduced size.

Implementation Method 1

The magnet includes a top portion, a bottom portion, and an outer portion. The first stator includes a first stator ring surrounding the outer portion of the magnet, and a plurality of first teeth extending from the first stator ring, the plurality of first teeth proximate the bottom portion of the magnet.

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 2

The magnetic sensing element is magnetically coupled to the first collector and the second collector

Methodology Applied
Scientific EffectMagnetic sensing: Hall Effect

Data Source

PatentEP3186131B1Low-height sensor for measuring torque angle
Publication Date: 2019.09.25 BOURNS INC
  • EP3186131B1 patent drawingFigure 1
  • EP3186131B1 patent drawingFigure 2A~2B
  • EP3186131B1 patent drawingFigure 3A

AI summary

A sensor for measuring a torque angle. The sensor includes a magnet, a first stator, a second stator, a first collector, a second collector, and a magnetic sensing element. The first stator includes a first horizontal ring section located on a first plane, and a plurality of first teeth extended from the first horizontal ring section, the plurality of teeth located on a second plane. The second stator includes a second horizontal ring section located on the second plane, and a plurality of second teeth extended from the second horizontal ring section, the plurality of second teeth located on the second plane. The first collector is located proximate the first horizontal ring section and the second collector is located proximate the second horizontal ring section. The magnetic sensing element is magnetically coupled to the first collector the second collector.