Rotor Winding Turn Reduction for Coil Retention
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Solution Overview
Problem
In electric motors with wound rotors, there is a risk of the last turns of the coil slipping off due to the limited diameter constraint, which can lead to malfunction, and existing solutions cannot prevent this without increasing the rotor size.
Innovation Solution
The rotor design features a cylindrical central core with radially extending arms, where the last coil has fewer turns than the preceding coils, and additional turns are wound between arms to overlap with the last coil, ensuring retention without increasing the rotor diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the rotor is limited to reduce machine size, then the rotor becomes more compact and easier to use in vehicles, but the last turns of the coil are at risk of slipping off during operation
Solution Approach 1:
The patent applies preliminary action by reducing the number of turns in the last coil before assembly, and adding retention elements (such as retaining rings or clips) that are pre-installed on the rotor arms to prevent turn slippage. This preventive measure is taken before the coil turns can slip off during operation, thereby maintaining reliability without increasing rotor diameter.
Solution Approach 2:
The patent introduces intermediary retention elements (retaining rings, clips, or similar components) that act as mediators between the coil turns and the rotor arms. These intermediaries mechanically constrain the last turns of the coil, preventing them from slipping off while allowing the rotor to maintain its compact size.
2Reliability
If the number of turns in the last coil is reduced to prevent slippage, then coil turn retention is improved, but the motor performance is slightly impaired
Solution Approach 1:
The patent applies local quality by making the last coil different from the other coils in the series. Specifically, the last coil has a reduced number of turns or modified structure only at the critical location where slippage occurs, while the majority of coils maintain their full turn count to preserve motor performance. This localized modification prevents slippage without significantly impacting overall power output.
3Reliability
If additional turns are wound between arms to overlap and retain the last coil turns, then coil turn retention is improved, but the device complexity increases
Solution Approach 1:
The patent merges the retention function with the existing coil winding structure by integrating retention elements into the winding process itself. The additional turns are wound in conjunction with the main coil assembly, combining the electrical function (coil turns) with the mechanical retention function in a single integrated structure, thereby reducing overall device complexity.
Data Source
AI summary
The present invention relates to a rotor (1) of a rotary electric machine, comprising:a body (3) comprising a cylindrical central core (5) and a circumferential plurality of arms (B1 . . . B18) extending radially out from the cylindrical central core (5), the body (3) being intended to be mounted with the ability to move about an axis of rotation X,a coilset produced by windings of turns and forming at least one series of coils (C1 . . . C9, C1′ . . . C9′), a coil (C1 . . . C9, C1′ . . . C9′) comprising a predetermined number of turns around at least two arms (B1 . . . B18) of the body (3), two adjacent coils (C1 . . . C9, C1′ . . . C9′) of a series being angularly offset from one another with a partial overlap,in which the last coil (C9, C9′), situated radially furthest towards the outside, comprises a predetermined number of turns that is lower than the predetermined number of turns of the other coils of the series (C1 . . . C8, C1′ . . . C8′).