Stator Core Wedge Fitting V-Groove Assembly
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Solution Overview
Problem
The existing stator core design for rotating electrical machines faces challenges with assembly workability and magnetic properties due to burr and shear droop issues during stamping, leading to increased manufacturing costs and performance degradation in torque and cogging.
Innovation Solution
A stator core design featuring an annular yoke portion with V-shaped grooves and a tooth group with wedge-shaped fitting portions, allowing for easier alignment and reduced press-fit force, along with a manufacturing method that stamps the core pieces from a thin magnetic sheet to minimize interference and enhance magnetic flux passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dovetail grooves and dovetail rails are formed by three surfaces with regular stamping, then the stator core structure is established, but the fitting precision deteriorates due to burr and shear droop expansion
Solution Approach 1:
The invention changes the geometric parameters of the fitting surfaces from three surfaces (dovetail shape) to two surfaces (wedge shape). This parameter change eliminates the expansion problem caused by burr and shear droop, as the wedge shape allows the fitting portion to be inserted along the groove without requiring precise alignment in multiple directions, thereby maintaining manufacturing precision while preserving ease of manufacture through stamping
Solution Approach 2:
Instead of trying to prevent burr and shear droop expansion through tighter tolerances or additional processing, the invention inverts the approach by designing a wedge-shaped fitting portion that accommodates the expansion naturally. The wedge shape allows the fitting to proceed even with dimensional variations, turning the harmful expansion effect into a non-critical factor
2Ease of manufacture
If the positions of teeth vary due to bending or stamping errors, then manufacturing flexibility is maintained, but assembly workability deteriorates requiring greater press-fit force
Solution Approach 1:
The invention changes the fitting geometry from a three-surface dovetail joint to a two-surface wedge joint. This parameter change reduces the degrees of freedom for misalignment, allowing positional variations from stamping and bending to be accommodated during assembly without requiring excessive press-fit force, thereby maintaining both manufacturing flexibility and assembly workability
3Ease of operation
If greater press-fit force is applied to accommodate position variations, then assembly is completed, but core distortion increases leading to deterioration in cogging and torque ripple
Solution Approach 1:
By changing the fitting surface geometry from three surfaces to two surfaces in a wedge configuration, the invention enables assembly completion with reduced press-fit force. The wedge shape provides a self-aligning effect that guides the fitting portion into the groove, preventing core distortion and maintaining reliability in terms of cogging and torque ripple performance
4Manufacturing precision
If additional processing steps are added to process the fitting portion after stacking, then fitting precision is improved, but manufacturing cost increases
Solution Approach 1:
The invention merges the fitting portion formation with the initial stamping process. The wedge-shaped fitting portion is formed directly during stamping of the tooth group, eliminating the need for separate post-stack processing steps. This integration maintains fitting precision while reducing manufacturing complexity and cost
Data Source
AI summary
A stator core for a rotating electrical machine includes an annular yoke portion; a tooth group fitted to an inner side of the yoke portion and formed such that both ends in a circumferential direction on an inner circumferential side of adjacent teeth are integrally connected with each other by a thin connection portion; and a slot for accommodating a stator winding. The yoke portion has grooves at regular intervals in an inner circumferential surface thereof and extending in an axial direction of the stator, the grooves each having a V shape such that a cross section thereof perpendicular to the axial direction opens toward an inner side of the stator core. Each tooth has, at an outer-circumferential-side end thereof, a fitting portion whose cross section perpendicular to the axial direction is formed in a wedge shape so as to allow the tooth to be fitted along the corresponding groove.