Stator Coil Bobbin Structure for Compact Trapezoidal Windings
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Solution Overview
Problem
Electric motors for electric bicycles face challenges in providing high torque and low rotational speed while maintaining a compact size, particularly due to the bulkiness of stator coils, which is exacerbated by the use of trapezoidal windings with ends facing toward the stator center.
Innovation Solution
A stator coil design featuring a bobbin with axial cutouts and retaining flanges, allowing trapezoidal windings with ends positioned toward the stator center, and a manufacturing method that positions commutators on the same side to reduce bulk and minimize the risk of short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a trapezoidal winding is used with ends facing toward the stator center to reduce bulk, then the motor size is minimized, but it becomes difficult to hold the turns in place and risk of short circuits increases
Solution Approach 1:
A bobbin is introduced as an intermediary component between the winding wire and the stator core. The bobbin includes a central shaft with channels and retaining flanges that guide and secure the winding wire turns, allowing the wire to be held in place without increasing the overall coil bulk. This mediator structure enables the trapezoidal winding configuration while preventing short circuits.
Solution Approach 2:
The bobbin structure is segmented into functional parts: a central shaft with multiple channels for guiding turns, retaining flanges at ends for securing the wire, and material cutouts for positioning commutators. This segmentation allows each part to perform its specific function in holding the winding wire securely while maintaining compact dimensions.
2Reliability
If retaining structures are added to hold winding turns in place, then reliability improves, but the bulk of the coil increases
Solution Approach 1:
The retaining structures (bobbin with channels and flanges) are merged with the coil structure itself rather than being separate components. The bobbin is positioned within the coil assembly and works integrally with the winding wire and stator core, providing retention functionality without adding external bulk to the motor assembly.
3Volume of moving object
If the number of layers of turns is varied to create trapezoidal winding, then bulk is reduced, but manufacturing complexity increases
Solution Approach 1:
The bobbin structure with pre-formed channels and retaining flanges is prepared in advance before the winding process. The channels are预先 positioned to guide the winding wire through the correct path for creating the trapezoidal winding pattern, simplifying the actual winding operation and ensuring consistent layer variation without complex manufacturing steps.
Data Source
AI summary
A coil of a stator for an electric motor is disclosed. The coil includes a bobbin which forms a tooth of the stator. The bobbin includes a tubular central shaft with a plurality of channels formed along its perimeter between a first end of the bobbin that is configured to face towards the middle of the stator. The bobbin also includes a first retaining flange situated on the first end of the central shaft, a second retaining flange situated on the second end of the central shaft, and a winding wire configured to be wound in the form of turns around the bobbin. The ends of the winding wire are positioned at the first end of the bobbin so as to enable electrical connections toward the center of the stator. The bobbin includes a material cutout extending between the first and second ends of the bobbin.