Bus Bar Unit With Projecting Portions For Insert Molding Support
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Solution Overview
Problem
The formation of through holes in bus bar units reduces the sectional area of the main body portion, leading to increased conductor resistance and a decrease in the current amount flowing through the bus bars during motor operation.
Innovation Solution
The bus bar unit design includes through holes with projecting portions on the side portions to increase the sectional area of the main body portion, which supports the insertion of support pins during insert molding, thereby maintaining the current flow by minimizing the reduction in sectional area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a through hole is formed in the bus bar main body portion to insert support pins during insert molding, then the bus bars can be properly supported and positioned, but the sectional area of the main body portion decreases leading to increased conductor resistance and reduced current flow
Solution Approach 1:
The bus bar is designed with non-uniform cross-sectional area, featuring a wider main body portion and a narrower portion at the through hole formation position. This local variation in geometry allows the through hole to be formed with minimal impact on the overall current carrying capacity, as the current primarily flows through the wider sections. The local quality change resolves the contradiction by concentrating the structural support function at the through hole location while maintaining high current flow capability in the main conduction paths.
Solution Approach 2:
The invention addresses the sectional area reduction problem by extending the bus bar in the axial direction to create an elongated structure. By adding this dimensional extension, the bus bar compensates for the area loss at the through hole location through increased length, thereby maintaining the overall electrical conductivity and current flow capability while enabling proper support pin insertion.
2Manufacturing precision
If a through hole is formed in the bus bar main body portion, then support pins can be inserted to maintain positional accuracy during insert molding, but the conductor resistance increases at the through hole formation position
Solution Approach 1:
The bus bar features a localized geometric variation where the main body portion has a larger cross-sectional area compared to the region around the through hole. This local quality differentiation ensures that the through hole formation does not significantly impact the overall electrical conductivity, as the current preferentially flows through the wider sections. The design maintains manufacturing precision for positional accuracy while minimizing the harmful effect of increased conductor resistance.
Solution Approach 2:
The bus bar is pre-designed with an optimized geometry that anticipates the through hole formation. The main body portion is deliberately made wider before the through hole is created, ensuring that even after hole formation, the remaining conductive path maintains sufficient cross-sectional area. This preliminary design action prevents the harmful effect of resistance increase before the through hole is actually formed during manufacturing.
Data Source
AI summary
In a bus bar unit in which a plurality of bus bars are formed by insert molding and arranged in an axial direction of a stator, each bus bar includes: a main body portion extending in a circumferential direction of the stator; a through hole formed in the main body portion, into which a support pin for supporting the main body portion of another bus bar is inserted in the axial direction of the stator during insert molding; and a projecting portion provided on a side portion of the main body portion in alignment with the through hole so as to increase a sectional area of the main body portion.