Rotor Core Step Skew Alignment Using Asymmetric Protrusions
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Solution Overview
Problem
In rotary electric machines with a step skew structure, gaps are generated between stacked core blocks due to burrs from punching, which can lead to foreign matter entry and separation of fixing members from the rotor core.
Innovation Solution
The rotor core is designed with central opening holes and protruding sections, including short and long sections, forming communication reference grooves that allow for correct alignment and stacking without reversing core blocks, reducing the gap between core blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If core blocks are stacked with reversed arrangement direction to achieve step skew structure, then torque ripple and magnetic noise are reduced, but gaps are generated between core blocks due to burr direction mismatch
Solution Approach 1:
The patent introduces asymmetric protruding sections with different lengths (first protruding section longer than second protruding section) to create an asymmetric reference structure. This asymmetric design allows the core blocks to be stacked in the same arrangement direction while still achieving the step skew structure, thereby eliminating the gap problem caused by burr direction mismatch while maintaining the torque ripple reduction benefit.
Solution Approach 2:
Instead of reversing the arrangement direction of core blocks to achieve step skew (conventional approach), the patent inverts the approach by using protruding sections of different lengths to indicate stacking order. This allows core blocks to be stacked in the same direction while still forming the step skew structure, thus avoiding the gap issue caused by opposite burr directions.
2Reliability
If core blocks are stacked with reversed arrangement direction to form step skew, then magnetic noise is reduced, but foreign matter can enter through gaps between core blocks
Solution Approach 1:
The asymmetric protruding sections create a unique stacking reference that allows core blocks to be assembled in the same direction. This eliminates gaps between core blocks, preventing foreign matter entry while maintaining the step skew structure necessary for magnetic noise reduction.
Solution Approach 2:
The patent converts the potentially harmful burrs into a beneficial alignment reference system. By designing protruding sections that extend from the burr sides of core sheets, the burrs are incorporated into the stacking reference mechanism, ensuring proper alignment and gap elimination while maintaining the step skew structure.
3Manufacturing precision
If core blocks are stacked with same arrangement direction using protruding sections as reference, then gap between core blocks is reduced, but step skew structure must be maintained
Solution Approach 1:
The patent segments the core block structure by introducing protruding sections as distinct elements. These protruding sections are formed by extending metal sheets and are integrated into the core block structure, providing clear stacking references without significantly increasing overall device complexity.
Solution Approach 2:
The patent applies local quality by creating protruding sections with different lengths at specific locations on core blocks. The first protruding section extends longer than the second protruding section, providing a localized asymmetric reference that guides the stacking process while maintaining the overall simplicity of the core block design.
Data Source
AI summary
In a rotary electric machine having a rotor core of a skew structure, when one of the core blocks is sequentially stacked on the other of the core blocks to form a step skew, a communication reference groove is formed along an axial direction of the rotor core by aligning a side section of a short protruding section in one core block with a side section of the long protruding sections in the other core block, and by aligning a side section of a long protruding section in one core block with a side section of a short protruding section in the other core block. The core blocks are correctly stacked by aligning the side section of the long protruding sections with the side section of the short protruding sections.