Stator Tooth Cap Assembly for Stable Insulation and More Copper Space

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Solution Overview

Problem

Existing electric machine stator designs require large and tolerantly wide caps for insulation, which are cumbersome and prone to misalignment, leading to potential insulation failures and inefficiencies due to the complexity of positioning and coupling the insulation papers and caps relative to the teeth.

Innovation Solution

The design features caps with interference coupling to the teeth, allowing for smaller dimensions and simplified positioning, where the insulation sheets rest on the caps after cap fixation, enabling easier handling and reduced operational complexity during winding, with flaps and wings providing stability and aiding in sheet retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large-sized caps with wide tolerances are used for insulation, then the insulation reliability is improved, but the overall size of the stator increases and the space for copper windings is reduced

Engineering Contradiction:
Improveinsulation reliabilityVSAvoidspace for copper windings
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The cap is divided into two distinct parts: a positioning element with precise geometric features (protrusions and recesses) that ensures accurate alignment, and a cap body that provides insulation. This segmentation allows the positioning function to be performed with high precision while the cap dimensions can be optimized for space efficiency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The positioning element acts as an intermediary between the cap and the tooth, providing a precise mechanical interface through protrusions and recesses. This intermediary mechanism ensures accurate positioning without requiring the cap itself to have large dimensions or wide tolerances, thereby preserving winding space while maintaining insulation reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If large-sized caps with wide tolerances are used for insulation, then the insulation stability is improved, but the device complexity increases

Engineering Contradiction:
Improveinsulation stabilityVSAvoidpositioning and coupling complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The positioning element enables self-positioning of the cap relative to the tooth through its geometric features (protrusions fitting into recesses). This self-service mechanism automatically ensures correct alignment during assembly, eliminating the need for complex external positioning procedures and reducing operational complexity while maintaining insulation stability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The complex mechanical positioning and coupling operations are replaced by a simple geometric interlocking system between the positioning element and the tooth. The protrusions and recesses create an automatic mechanical guide that simplifies the assembly process and reduces the skill level required for proper installation, thereby reducing device complexity while ensuring stable insulation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If precise positioning operations are performed to prevent insulation paper movement, then the insulation quality is improved, but the manufacturing time and operational complexity increase

Engineering Contradiction:
Improveinsulation paper positioning precisionVSAvoidassembly time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The positioning element is pre-installed on the tooth before the cap and insulation paper are assembled. This preliminary action creates a pre-established geometric reference framework that guides subsequent assembly steps, ensuring precise positioning of the insulation paper without requiring time-consuming adjustments or complex positioning operations during the main assembly process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The geometric features of the positioning element (protrusions and recesses) automatically guide and constrain the insulation paper and cap into their correct positions during assembly. This self-guiding mechanism eliminates the need for operator intervention to achieve precise positioning, thereby maintaining high manufacturing precision while significantly reducing assembly time and operational complexity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4336710A1Electric machine stator, and method for manufacturing such a stator
Publication Date: 2024.03.13 FERRARI SPA
  • EP4336710A1 patent drawingFigure 1~2
  • EP4336710A1 patent drawingFigure 3~4
  • EP4336710A1 patent drawingFigure 5

AI summary

An electric machine stator has a core (2) of ferromagnetic material, consisting of a plurality of teeth (3) arranged around a longitudinal axis (A) and defining a plurality of slots (4) between them; the stator has, for each tooth (3), an insulating cap (14) fixed to a longitudinal end of the tooth (3) by means of an interference coupling and provided with front projections (19,22) facing and spaced apart from one another in a radial direction; the windings (26), which are made of electrically conductive material, extend in the half-slots (4a) arranged on opposite sides of each tooth (3) and around the cap (14), between said front projections (19,22) in a radial direction; each half-slot (4a) carries at least one sheet (29) of foldable insulating material, which has a C-shaped portion (30), which is interposed between the first wire portions (26a) and the tooth (3), and at least one flap (36,35), which longitudinally projects from said C-shaped portion (30) out of the corresponding half-slot (4a) and radially rests on an end portion (20) that is part of one of said front projections (19,22).