Wound Rotor Pole Sequence for Robust Wire Crimping

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Solution Overview

Problem

The existing wound rotor designs for electric machines face issues with mechanical robustness due to poor wire routing and crimping, leading to potential wire slippage, breakage, and mechanical stress under centrifugal forces and vibrations, which complicates the winding process and affects the reliability of connections.

Innovation Solution

A wound rotor design where the winding wire is arranged with poles in a specific order around the main axis, with lugs facilitating the winding process, and the wire rests at non-zero angles before and after the poles, ensuring optimal contact and crimping, thereby enhancing mechanical robustness and reducing stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the winding wire is routed in a conventional sequential order (first to last pole), then the winding process is simple, but the wire positioning in connection hooks is incorrect leading to poor mechanical robustness

Engineering Contradiction:
Improvewinding process simplicityVSAvoidconnection mechanical robustness
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent inverts the conventional winding sequence by winding the last pole before the first pole, and the penultimate pole after the last pole. This reversal of the winding order allows the wire to be correctly positioned in the connection hooks while maintaining a simple sequential winding process, thereby resolving the contradiction between manufacturing simplicity and connection reliability.

Inventive Principle:
Principle #13The other way round (Inversion)

2Productivity

If the wire is crimped at connection hooks with conventional routing, then the connection is formed quickly, but residual stresses and centrifugal forces cause wire slippage and breakage

Engineering Contradiction:
Improveconnection formation speedVSAvoidwire connection strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The patent applies preliminary action by pre-positioning the wire at specific non-zero angles around the main axis before crimping occurs. The wire is arranged to rest against the shaft at predetermined angular positions, ensuring optimal positioning before the crimping operation. This preliminary arrangement prevents wire slippage and breakage under centrifugal forces while maintaining quick connection formation.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the wire rests at non-zero angles around the main axis, then mechanical robustness is improved, but the winding process complexity increases

Engineering Contradiction:
Improvewire connection reliabilityVSAvoidwinding process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the angular position parameter of the wire around the main axis, specifying non-zero angles for wire placement upstream of the first pole and downstream of the last wound pole. By defining specific angular parameters for wire positioning, the patent achieves improved mechanical robustness while keeping the winding process manageable through parameter specification rather than complex procedural changes.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4088370B1Method for winding an electric machine rotor
Publication Date: 2024.01.31 NISSAN MOTOR CO LTD
  • EP4088370B1 patent drawingFigure 1
  • EP4088370B1 patent drawingFigure 2
  • EP4088370B1 patent drawingFigure 3

AI summary

The invention relates to a wound rotor (20), in particular a wound rotor (20) for an electric machine (30), the wound rotor (20) comprising a shaft (21) having a main axis (A), the shaft (21) comprising a manifold (22), the wound rotor (20) comprising a winding wire (25) and n poles (1, 2, 3,... n-2, n-1, n) wound and ordered with an ascending order number obtained by rotation about the main axis (A), in particular n wound poles (1, 2, 3, …, n-2, n-1, n) distributed radially about the main axis (A), the n poles being wound with the wire (25) in series in turn according to their ascending order numbers, the last pole (n), however, not being wound last.