Rotor Core Segmentation Using Auxiliary Non-Magnetic Sheets

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Solution Overview

Problem

Conventional motor manufacturing methods require the same number of stator and rotor core sheets, leading to inefficiencies and increased costs due to the need for additional stator core sheets when producing rotor cores with different sheet counts.

Innovation Solution

A motor design that includes a rotor with permanent magnets and a tubular non-magnetic cover, featuring stacked cores with varying hardness materials, where auxiliary rotor core sheets made from softer SPCC steel are used to match the number of rotor core sheets, reducing manufacturing complexity and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If magnetic plates are added to the stator core to increase motor output, then the motor output is improved, but the axial length of the stator core increases requiring more rotor core sheets than stator core sheets

Engineering Contradiction:

Improvemotor outputVSAvoidnumber of rotor core sheets vs stator core sheets

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The rotor core sheets are divided into two types: main rotor core sheets (punched from magnetic steel sheets) and auxiliary rotor core sheets (made from non-magnetic steel plates). This segmentation allows the rotor core to be constructed with a different number of sheets than the stator core, resolving the mismatch caused by adding magnetic plates to the stator core.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials are used for different portions of the rotor core. The main rotor core sheets use magnetic steel for electromagnetic interaction, while the auxiliary rotor core sheets use non-magnetic steel to complete the structural length without requiring corresponding magnetic steel sheets, thus avoiding the need for equal sheet numbers.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the same number of stator core sheets and rotor core sheets are manufactured from the same magnetic steel sheets, then the manufacturing process is simplified, but insufficient rotor core sheets are produced when more rotor sheets are needed

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidnumber of rotor core sheets

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

Non-magnetic steel plates serve dual purposes: they function as auxiliary rotor core sheets to complete the rotor core structure, and they can be produced independently from magnetic steel sheets. This multi-functionality allows the manufacturing process to produce sufficient rotor core sheets without being constrained by the number of magnetic steel sheets available for stator core production.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Quantity of substance

If additional stator core sheets are produced to match the required number of rotor core sheets, then the sheet quantity mismatch is resolved, but manufacturing costs increase due to unnecessary stator core sheets

Engineering Contradiction:

Improvenumber of rotor core sheetsVSAvoidunnecessary stator core sheets

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The auxiliary rotor core sheets are extracted from the requirement to use magnetic steel sheets. By using non-magnetic steel plates for auxiliary sheets, the patent removes the constraint that all rotor core sheets must be punched from magnetic steel, thereby eliminating the need to produce extra stator core sheets and reducing material waste.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If harder magnetic steel is used for rotor core sheets, then the magnetic properties are improved, but the sheets are more difficult and expensive to manufacture

Engineering Contradiction:

Improvemagnetic propertiesVSAvoidmanufacturing difficulty and cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Different material properties are assigned to different rotor core sheets based on their functional requirements. Main rotor core sheets use hard magnetic steel for electromagnetic interaction, while auxiliary rotor core sheets use softer non-magnetic steel that is easier and less expensive to manufacture, optimizing both performance and cost.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11296563B2Rotor, motor, method for manufacturing rotor, and method for manufacturing motor

Publication Date: 2022.04.05 DENSO CORP

AI summary

A rotor includes a rotor core, permanent magnets, and a tubular non-magnetic cover. The permanent magnets are arranged along an outer surface of the rotor core in the circumferential direction. The permanent magnets each include a curved outer surface as viewed in the axial direction. The tubular non-magnetic cover covers the outer surfaces of the permanent magnets. The rotor core includes at least two stacked cores. Each stacked core includes a stack of core sheets. One of the stacked cores is formed from a material having a lower hardness than the other stacked core.