Extended Stator Core Ends for Axial Position Stability

Solution Overview

Problem

Rotating electrical machines with non-contact bearings, such as magnetic or fluid bearings, face challenges in maintaining axial position stability due to assembly errors, leading to axial displacement and vibration, which can degrade processing accuracy in machine tools.

Innovation Solution

The design includes a torque generation section with extended stator core ends and aligned intermediate positions in the axial direction, utilizing non-contact bearings like magnetic, fluid, or hybrid bearings to maintain axial position stability through balanced magnetic forces, suppressing axial displacement and vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-contact bearings (magnetic, pneumatic, or fluid bearings) are used for the rotating shaft, then friction and wear are reduced, but axial displacement and vibration occur due to assembly errors and forces in the axial direction

Engineering Contradiction:

Improvereduction of friction and wearVSAvoidaxial position stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent converts the harmful axial forces generated by assembly errors into a beneficial effect by extending the stator core ends to create additional magnetic interaction zones. These zones generate restoring magnetic forces that automatically counteract axial displacement, transforming the problematic force generation into a self-correcting mechanism without requiring active control systems.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The extended stator core configuration enables the motor to self-regulate axial position through passive magnetic forces. The magnetic field interaction between the extended stator core ends and rotor components automatically generates restoring forces when axial displacement occurs, eliminating the need for external active control systems or complex bearing mechanisms.

Inventive Principle:

Principle #25Self-service

2Stability of the object's composition

If active magnetic bearing with feedback control is used to maintain axial position, then axial position stability is improved, but device complexity and cost increase

Engineering Contradiction:

Improveaxial position stabilityVSAvoidcomplexity of feedback control system

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The extended stator core configuration enables the motor to self-regulate axial position through passive magnetic forces. The magnetic field interaction between the extended stator core ends and rotor components automatically generates restoring forces when axial displacement occurs, eliminating the need for external active control systems or complex bearing mechanisms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the axial position stabilization function from complex active control systems and integrates it directly into the motor structure through extended stator core ends. This structural modification creates inherent magnetic restoring forces that eliminate the need for separate feedback control systems, sensors, and power electronics.

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If passive magnetic bearing is used without feedback control, then device complexity is reduced, but axial position stability deteriorates due to lack of positional restoration function

Engineering Contradiction:

Improvesimplicity of bearing systemVSAvoidaxial position stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent converts the harmful axial forces generated by assembly errors into a beneficial effect by extending the stator core ends to create additional magnetic interaction zones. These zones generate restoring magnetic forces that automatically counteract axial displacement, transforming the problematic force generation into a self-correcting mechanism without requiring active control systems.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The extended stator core configuration enables the motor to self-regulate axial position through passive magnetic forces. The magnetic field interaction between the extended stator core ends and rotor components automatically generates restoring forces when axial displacement occurs, eliminating the need for external active control systems or complex bearing mechanisms.

Inventive Principle:

Principle #25Self-service

4Manufacturing precision

If axial displacement occurs in the rotating shaft of a machine tool spindle, then processing accuracy is maintained, but manufacturing cost and complexity increase

Engineering Contradiction:

Improveprocessing accuracyVSAvoidcomplexity of axial position control

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The extended stator core configuration enables the motor to self-regulate axial position through passive magnetic forces. The magnetic field interaction between the extended stator core ends and rotor components automatically generates restoring forces when axial displacement occurs, eliminating the need for external active control systems or complex bearing mechanisms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the axial position stabilization function from complex active control systems and integrates it directly into the motor structure through extended stator core ends. This structural modification creates inherent magnetic restoring forces that eliminate the need for separate feedback control systems, sensors, and power electronics.

Inventive Principle:

Principle #2Taking out (Extraction)

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 allows for accurate and cost-effective maintenance of the axial position of the rotating shaft, minimizing axial displacement and vibration, even with passive bearings, enhancing processing accuracy and reducing manufacturing complexity and costs.

Implementation Method 1

a force will be generated in the axial direction

Methodology Applied

Scientific EffectMagnetic force: Magnetism

Implementation Method 2

a force will be generated in the axial direction

Methodology Applied

Scientific EffectMagnetic force: Magnetism

Data Source

PatentUS10424978B2Rotating electrical machine comprising stator core, and machine tool comprising the same

Publication Date: 2019.09.24 FANUC LTD

AI summary

To provide a rotating electrical machine which can be easily configured at low lost, and which can highly accurately maintain an axial position (position in a thrust direction) of a rotating shaft in a prearranged position, and a machine tool, to which the rotating electrical machine is applied. A rotating electrical machine includes: a stator including a stator core; and a rotor supported on a rotating shaft supported by way of a non-contact bearing. When a section, in which a torque generation member exists in an axial direction of the rotating electrical machine, is defined as a torque generation section, a first end and a second end of the stator core in the axial direction extend outwards in the axial direction from a first end and a second end of the torque generation section at the rotor side in the axial direction. According to one aspect of the present invention, a length of the first end and the second end of the stator core extending outwards in the axial direction, from the first end and the second end of the torque generation section at the rotor side in the axial direction, is longer than a magnetic gap length of the rotating electrical machine.