Vehicle AC Generator Stator Anti-Rust Coating via Inner Surface Varnish

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Solution Overview

Problem

Conventional stator manufacturing for vehicle AC generators faces challenges such as limited space for grounding tooth portions, complex masking requirements, and uneven coating between laminates, leading to difficulties in achieving uniform anti-rust coatings and high production costs.

Innovation Solution

The stator core is formed by laminating thin steel sheets with varnish filled between laminates and coated with epoxy resin varnish on the inner diameter end surface, allowing for uniform film formation and improved anti-rust properties without the need for extensive facility investment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If electrodeposition coating is used to form insulation film on tooth portion, then continuous film with sufficient thickness can be formed, but tooth portion must be grounded as cathode which requires extensive masking and facility investment

Engineering Contradiction:
Improvecoating film uniformityVSAvoidgrounding space requirement
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the grounding requirement from the tooth portion by applying coating only to the inner peripheral surface of the stator core, eliminating the need for complex grounding and masking facilities while achieving sufficient insulation coverage

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different coating strategies to different regions: the inner peripheral surface receives anti-rust coating for protection, while the tooth portion relies on sufficient insulation from the laminated structure itself, eliminating the need for electrodeposition on teeth

Inventive Principle:
Principle #3Local quality

2Reliability

If paint with high anti-rust properties but low penetration properties is sprayed on inner peripheral surface, then anti-rust protection is improved, but paint is drawn between laminates and uniform coating thickness cannot be ensured

Engineering Contradiction:
Improveanti-rust propertiesVSAvoidcoating film uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary anti-rust treatment to the inner peripheral surface before final assembly, ensuring rust protection is established before the stator operates, while controlling the coating application to prevent excessive paint migration between laminates

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If stator core has increased number of slots and teeth (1.5-2 times conventional), then electromagnetic performance is improved, but tooth width becomes narrower and available space for grounding decreases

Engineering Contradiction:
Improveelectromagnetic performanceVSAvoidgrounding space
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the grounding requirement from narrow tooth portions by shifting the coating application to the inner peripheral surface, allowing high-performance stator designs with narrow teeth without compromising insulation coverage

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 method simplifies the coating process, ensures excellent anti-rust properties, reduces production costs, and enhances heat dissipation and electromagnetic stability, making it suitable for mass production.

Implementation Method 1

The stator core is filled with varnish between the laminates of each tooth at least in an inner diameter end surface region which faces said rotor, and is coated with epoxy resin varnish on the tooth surface of the inner diameter end surface region to form an anti-rust film with a uniform film thickness

Methodology Applied
Scientific EffectVarnish coating: Coatings

Data Source

PatentEP2448090B1Stator of vehicle ac generator and method for manufacturing the same
Publication Date: 2020.02.26 MITSUBISHI ELECTRIC CORP
  • EP2448090B1 patent drawingFigure 1~2
  • EP2448090B1 patent drawingFigure 3~4
  • EP2448090B1 patent drawingFigure 5~6

AI summary

In a vehicle AC generator, a stator core (42) is formed by laminating thin steel sheets, the stator core (42) being provided with a plurality of slot portions (43) which accommodate a stator winding (41) and tooth portions (44) which define adjacent ones of the slot portions; the stator winding (41) is disposed in the slot portions to constitute a stator (4) ; the stator core (42) is filled with varnish (45) between laminates of each tooth (44) at least in an inner diameter end surface region which faces the rotor (3) and is coated with epoxy resin varnish (46) on the tooth surface of the inner diameter end surface region to form an anti-rust film.