Slanted Stator Core Fit for High-Torque Housing Fixation

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Solution Overview

Problem

Conventional press-fit fixing structures for stator cores in rotating electric machines require complex machining, increasing costs, and there is a need for a low-cost solution that improves the fixing force while minimizing deformation.

Innovation Solution

The stator cores are arranged in an annular shape with outer circumferential surfaces slanted relative to the housing's inner surface, utilizing a twisted or asymmetrical shape to enhance the fixing force through interference fit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the fixing force is increased to cope with increased torque, then the fixing strength is improved, but the stator core may be deformed causing deterioration of magnetic characteristics and buckling phenomenon

Engineering Contradiction:
Improvefixing strengthVSAvoidstator core deformation
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention applies local quality by creating protrusions only at specific locations on the stator core outer circumferential surface and corresponding recesses on the housing inner circumferential surface, rather than uniformly increasing fixing force across the entire surface. This localized interference fit structure concentrates the fixing effect at key positions while distributing stress to avoid deformation of the stator core body, thus improving fixing strength without compromising manufacturing precision.

Inventive Principle:
Principle #3Local quality

2Strength

If a press-fit fixing structure with uneven shapes is used to improve fixing force, then the fixing strength is improved, but complicated machining is required increasing manufacturing cost

Engineering Contradiction:
Improvefixing strengthVSAvoidmachining complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention segments the fixing structure into discrete protrusions and recesses rather than requiring complex continuous uneven surfaces. These segmented features can be manufactured using standard molding or machining processes, significantly reducing manufacturing complexity while still providing enhanced fixing strength through the interference fit mechanism at multiple discrete locations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention employs asymmetric protrusion and recess geometries that are optimized for interference fit functionality rather than symmetric decorative patterns. The asymmetric design allows the features to be integrated into standard manufacturing processes while achieving the desired fixing strength, avoiding the need for complex symmetric machining operations.

Inventive Principle:
Principle #4Asymmetry

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 improved stator core fixation at a lower cost without complex machining, providing high fixing force against both regenerative and driving torques.

Implementation Method 1

Each of the stator cores 400 has outer circumferential surfaces 410, 420 which are slanted with respect to the inner circumferential surface 510 of the housing 500. The outer circumferential surfaces 410, 420 of the stator core 400 are slanted in the same direction with respect to the inner circumferential surface 510 of the housing 500.

Methodology Applied
Scientific EffectInterference fit: Friction

Data Source

PatentEP3748815B1Dynamo-electric machine and stator
Publication Date: 2025.12.24 ASTEMO LTD
  • EP3748815B1 patent drawingFigure 1
  • EP3748815B1 patent drawingFigure 2
  • EP3748815B1 patent drawingFigure 3

AI summary

An object of the present invention is to improve the fixing force of a stator core at low cost. The rotating electric machine includes a stator 300 in which a plurality of stator cores 400 are annularly arranged, a rotor to be arranged on the inner circumferential side of the stator 300, and a housing 500 having a cylindrical shape for fixing each of the plurality of stator cores 400. The stator core 400 has outer circumferential surfaces 410 and 420 arranged to face the inner circumferential surface 510 of the housing 500, and the outer circumferential surfaces 410 and 420 of the stator core 400 are slanted with respect to the inner circumferential surface 510 of the housing 500.