Stator Resin Sealing Layout to Reduce Eddy-Current Loss

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Solution Overview

Problem

The existing stator sealing methods, where resin is injected from the top or bottom, cause coil conductive wires to be displaced radially, leading to increased eddy-current loss due to higher magnetic flux density at the tooth tip.

Innovation Solution

A stator design with a resin portion having a gate mark positioned to overlap with the coil in the radial direction, and an insulating member to restrain coils from moving radially, allowing for controlled resin injection from the outer side of the stator core, ensuring the coils are fixed towards the yoke, reducing eddy-current loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the sealing resin material is injected from the top side or bottom side in the vertical line direction of the stator core, then the sealing resin material can be injected into the mold, but the coil conductive wires are forced out to the tooth tip side in the radial direction, causing increased eddy-current loss

Engineering Contradiction:

Improvesealing resin injectionVSAvoideddy-current loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent inverts the conventional injection direction from vertical (top or bottom) to radial (inner peripheral side toward outer peripheral side). This inversion changes the force direction acting on the coil conductive wires, preventing them from being pushed toward the tooth tip side and thereby reducing eddy-current loss while maintaining effective sealing.

Inventive Principle:

Principle #13The other way round (Inversion)

2Loss of energy

If the sealing resin material is injected from the inner peripheral side in the radial direction, then the coil conductive wires are pushed toward the outer peripheral side, but this may cause displacement of coils and increased stress on welding points

Engineering Contradiction:

Improveeddy-current lossVSAvoidwelding connection reliability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent performs preliminary action by strategically positioning the gate on the outer side of the stator core end face before injection. This positioning ensures that the resin flows in a controlled manner, pushing coils toward the yoke rather than allowing excessive displacement, thereby maintaining welding connection reliability while reducing eddy-current loss.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by positioning the gate specifically on the outer side of the end face rather than uniformly distributing injection points. This localized injection approach creates controlled pressure zones that push coils toward the yoke structure, providing stable positioning without excessive stress on welding points.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If the gate is positioned on the outer side of the end face overlapping with the coil, then the coil is pushed toward the yoke reducing eddy-current loss, but burrs are formed on the resin portion requiring deburring

Engineering Contradiction:

Improveeddy-current lossVSAvoidpost-processing requirement

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent converts the harmful effect of burr formation into a beneficial outcome. By positioning the gate on the outer side of the end face, the resin injection process creates controlled burrs that indicate successful coil positioning toward the yoke. The burrs are subsequently removed through deburring, but their formation serves as a marker that the injection achieved the desired coil stabilization, thereby reducing eddy-current loss.

Inventive Principle:

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

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 effectively suppresses the increase in eddy-current loss by ensuring the coils are securely positioned, improving the reliability of the electrical connection and reducing stress on the welding points.

Implementation Method 1

an injection step of, subsequent to the placement step, in the mold, injecting a sealing resin material into the cavity from a gate positioned facing and overlapping with the coil in the radial direction of the stator core, on outer side with respect to an end face of the stator core in direction of the axis

Methodology Applied

Scientific EffectResin injection:

Implementation Method 2

a curing step of, subsequent to the injection step, curing the sealing resin material injected

Methodology Applied

Scientific EffectCuring: Photopolymerisation

Data Source

PatentUS20230308000A1Stator and stator sealing method

Publication Date: 2023.09.28 TOYOTA JIDOSHA KK

AI summary

A stator comprises a cylindrical stator core centered on an axis, a coil arranged wound around a tooth disposed on the stator core, the tooth protrudes to one side in radial direction of the stator core, and the stator comprises a resin portion sealing up each of the stator core and the coil, the resin portion has a gate mark that lies on one side with respect to the coil in the radial direction of the stator core, the gate mark lies on outer side with respect to an end face of the stator core in the axial direction, the gate mark overlaps in position with the coil in the radial direction of the stator core.