Rotor Core Welding Segmentation for Thin Steel Sheet Deformation

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Solution Overview

Problem

Conventional rotors face issues with insufficient joining of the core to the shaft, leading to potential deformation and core opening due to welding heat, especially with thin magnetic steel sheets, which affects the rotor's stability and performance.

Innovation Solution

A rotor design featuring a core with a through hole for the shaft, where inner-peripheral-side welding joins the magnetic steel sheets to the shaft, and outer-peripheral-side welding joins the sheets at the end faces, preventing slippage and deformation while minimizing the impact on the electromagnetic circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic steel sheets are welded to the shaft over the laminating direction, then the core is securely fixed to the shaft, but the welding heat causes deformation and warping of the thin steel sheets

Engineering Contradiction:
Improvefixation stabilityVSAvoidcore shape accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The welding process is divided into two distinct stages: first welding the steel sheets to each other on the inner peripheral side, then welding the core end face to the shaft. This segmentation allows each welding operation to be optimized independently, preventing excessive heat accumulation that would cause deformation while ensuring secure fixation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The steel sheets are preliminarily welded to each other on the inner peripheral side before the core is welded to the shaft. This preliminary action creates a stable laminated structure that can better withstand the subsequent welding heat, preventing warping and maintaining manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

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 ensures a stable and secure fixation of the rotation transmitting member to the core, preventing core opening and maintaining the rotor's performance and power efficiency by controlling the welding process and placement of welded sections.

Implementation Method 1

an inner-peripheral-side welded part provided on an inner peripheral side of the core to join between the magnetic steel sheets constituting the laminated steel sheet assembly, the inner-peripheral-side welded part being a welded section that joins the laminated steel sheets to the rotation transmitting member over a laminating direction of the magnetic steel sheets

Methodology Applied
Scientific EffectWelding: Welding

Implementation Method 2

an outer-peripheral-side welded part provided on an outer peripheral side of the core and at an end in the laminating direction, the outer-peripheral-side welded part being a welded section that joins between some of the steel sheets, including a steel sheet forming an end face of the core in the laminating direction

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP2549623B1Rotor and method of manufacturing the rotor
Publication Date: 2017.09.27 TOYOTA JIDOSHA KK
  • EP2549623B1 patent drawingFigure 1
  • EP2549623B1 patent drawingFigure 2
  • EP2549623B1 patent drawingFigure 3

AI summary

A rotor (100) includes a core (11) made of a laminated steel sheet assembly including a plurality of laminated magnetic steel sheets (21) each having a flat plate shape, the core (11) including a through hole (26) at a rotation center, a shaft (12) inserted in a through hole (26) of the core (11), an inner-peripheral-side welded part (29) located on an inner peripheral side of the core (11), the welded part (29) being a welded section joining between adjacent steel sheets (21) and joining the laminated steel sheet assembly to the shaft (12) over a laminating direction, and an outer-peripheral-side welded part (32) located on an outer peripheral side of the core (11) and in an end part in the laminating direction, the welded part (32) being a welded section joining between some of the magnetic steel sheets (21), the joined steel sheets including a steel sheet (21U) forming an end face of the core (11) in the laminating direction.