Stator Bobbin Gap-Hole Layout for Motor Inductance Control
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Solution Overview
Problem
The rotary electrical machine's controllability is affected by varying inductance due to the distance between segment coils and the stator's back yoke, leading to potential defective molding issues from resin stagnation during bobbin manufacturing.
Innovation Solution
Incorporating a first gap hole in the back-yoke-side side wall of the bobbin to distance the armature winding from the back yoke, reducing inductance and resin stagnation, thereby enhancing controllability and preventing molding defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the side wall of the bobbin is locally increased to secure the distance between segment coil and back core, then the controllability is improved, but the resin stagnation occurs during resin molding causing defective molding
Solution Approach 1:
The side wall of the bobbin is divided into multiple regions with different thicknesses. Specifically, the first side wall portion (near the back core) has a greater thickness than the second side wall portion (near the slot opening), creating a stepped structure that segments the wall thickness to optimize both electrical performance and molding quality
Solution Approach 2:
Different portions of the bobbin side wall are given different thicknesses according to their functional requirements. The region near the back core has increased thickness to maintain proper distance and controllability, while other regions maintain standard thickness to ensure proper resin flow and eliminate stagnation during molding
2Productivity
If the distance between segment coil and back core is reduced to achieve downsizing, then the productivity is improved, but the inductance increases causing controllability to decrease
Solution Approach 1:
The bobbin side wall thickness is locally optimized at different positions. The first side wall portion near the back core has increased thickness to maintain the necessary distance for proper inductance and controllability, while the overall bobbin dimensions are reduced to achieve downsizing and improved productivity
Data Source
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AI summary
There included are a rotor (3), a stator core (21) having a plurality of slots (21c) between the rotor (3) and a back yoke (21a), resin bobbins (22) each of which includes a plurality of coil insertion holes (22a) arranged along a radial direction of the stator core (21) and is fit into the slot (21c), and a first gap hole (22ca) provided to a side wall (22c) that is closest to the back yoke (21a) among side walls of the bobbin (22).