Rotor Lamination Cutout Sensing for Shorter Motor Position Detection

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Solution Overview

Problem

Existing motor position sensor systems for rotating electric machines, such as PMSMs, require additional axial space and are prone to errors due to magnet dislocation or demagnetization, increasing manufacturing costs and motor length.

Innovation Solution

A motor position sensor system with axially stacked laminations and progressively smaller cutouts that create a variable reluctance path, integrated with motor sensors and magnets on a printed circuit board, reducing the need for separate gear teeth and minimizing axial space, while maintaining robust mechanical structure and low cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gear-tooth sensor or permanent magnet-based sensor systems are used for rotor position sensing, then position detection capability is improved, but axial length of motor housing increases significantly

Engineering Contradiction:

Improverotor position detection accuracyVSAvoidaxial length of motor housing

Core Design Contradiction:

Measurement precisionVSLength of stationary object

Solution Approach 1:

The sensor system is merged with the rotor structure by integrating sensor magnets and sensors directly onto the rotor, eliminating the need for separate gear-tooth arrangements or dedicated sensor housing space. This integration allows position sensing without increasing axial length.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from axial arrangement (separate sensor housing at end of motor) to radial arrangement (sensors and magnets on rotor surface), utilizing the radial dimension of the rotor to accommodate the sensing system without extending axial length.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If permanent magnet-based sensor system is used, then position sensing performance is improved, but manufacturing cost increases

Engineering Contradiction:

Improveposition sensing performanceVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The rotor structure serves multiple functions: it provides mechanical rotation drive and simultaneously houses the position sensing system through integrated magnets and sensors, eliminating the need for separate sensing components and reducing manufacturing cost.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The rotor structure itself provides the mounting platform and structural support for the sensing system, utilizing existing rotor components rather than requiring additional dedicated parts, thereby reducing overall manufacturing cost.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If permanent magnet-based sensor system is used, then position detection capability is improved, but reliability decreases due to magnet falling off or dislocation

Engineering Contradiction:

Improveposition detection capabilityVSAvoidsensor system reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

By merging the sensor magnets and sensors directly onto the rotor structure, the system eliminates the need for separate permanent magnet assemblies that could detach or dislocate, improving reliability through integrated construction.

Inventive Principle:

Principle #5Merging (Combining)

4Strength

If gear-tooth sensor system is used, then robust mechanical structure is achieved, but axial length of motor increases

Engineering Contradiction:

Improvemechanical structure robustnessVSAvoidaxial length of motor

Core Design Contradiction:

StrengthVSLength of stationary object

Solution Approach 1:

The patent moves the sensing arrangement from axial dimension (gear-tooth arrangements extending axially) to radial dimension (magnets and sensors on rotor surface), maintaining mechanical robustness while reducing axial length.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design provides accurate rotor position detection with reduced axial motor length and cost, enhancing reliability and efficiency by eliminating the need for separate gear teeth and minimizing magnet-related errors.

Implementation Method 1

As the rotor and the magnetic gear rotate, the field of the sensor-magnet will experience variable reluctance path

Methodology Applied

Scientific EffectMagnetic reluctance: Magnetic Reluctance

Data Source

PatentUS12149131B2Motor position sensing system for rotating electric machines

Publication Date: 2024.11.19 STEERING SOLUTIONS IP HOLDING CORP

AI summary

An electric machine includes a rotor structure disposed within a motor housing, wherein a second rotor end has a plurality of axially stacked laminations. The electric machine further includes a motor position sensor system which includes a first plurality of cutouts defined in the plurality of axially stacked laminations, wherein the first plurality of cutouts have a progressively smaller cross-sectional area at each lamination. The motor position sensor system also includes a second plurality of cutouts defined in the plurality of axially stacked laminations, wherein the second plurality of cutouts have a progressively smaller cross-sectional area at each lamination. The motor position sensor system further includes a plurality of motor sensors axially spaced from the second rotor end, and a plurality of sensor magnets axially spaced from the second rotor end and the plurality of motor sensors.