Bus Bar Layout in Current Sensors to Prevent Molding Short Circuits
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Solution Overview
Problem
Current sensors for electric vehicle inverters face challenges in miniaturization and preventing short circuits between bus bars due to deflection caused by resin filling pressure during insert molding, which complicates the molding process and increases the risk of short circuits.
Innovation Solution
The design features bus bars with specific conductor portions arranged in different directions to maintain insulation and prevent overlap, allowing for reduced mold complexity and increased insulation distance, thereby minimizing the risk of short circuits and enabling smaller sensor sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pitch between connection portions is reduced to miniaturize the current sensor, then the size of the current sensor is reduced, but the connection portions may be deflected by resin filling pressure during insert molding causing short circuit
Solution Approach 1:
The connection portions are arranged in a planar configuration where they extend in different directions (first direction for length, second direction for width, third direction for thickness) rather than stacking them in one dimension. This multi-dimensional arrangement allows reduced pitch while maintaining insulation distance, preventing deflection-induced short circuits during insert molding
Solution Approach 2:
Each connection portion has locally optimized geometry with specific width and thickness dimensions. The width is designed to be sufficient to resist deflection from resin filling pressure, while the thickness provides structural rigidity. This local quality optimization allows compact arrangement without compromising reliability
2Reliability
If positioning pins are added to the mold to press connection portions during molding, then short circuit is prevented, but the mold becomes complicated and more difficult to process
Solution Approach 1:
The connection portions are designed with inherent geometric features (width, thickness, and directional arrangement) that enable them to maintain proper spacing and insulation distance automatically during the insert molding process. The structure itself provides the positioning and spacing function that would otherwise require additional positioning pins, eliminating the need for complex mold modifications
Solution Approach 2:
The positioning and spacing function is extracted from the mold system and integrated into the connection portions themselves. By incorporating the positioning capability directly into the bus bar structure, the mold design is simplified and the manufacturing process becomes easier while still preventing short circuits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses short circuits by maintaining adequate insulation distances and reduces the complexity of the molding process, allowing for a more compact current sensor while ensuring reliable operation.
Implementation Method 1
a magnetic detection portion arranged corresponding to each of the bus bars for detecting a magnetic field formed when current is flowing in each of the bus bars
Data Source
AI summary
A current sensor includes: plate-shaped bus bars; a magnetic detection portion; and a shell holding the bus bars. The bus bars are arranged in a first direction. At least some of the bus bars have: a first conductor portion extending in the first direction; a second conductor portion connected to one end of the first conductor portion and extending in a second direction crossing the first direction; and a third conductor portion connected to the other end of the first conductor portion and extending in a third direction. The bus bars at least include first and second bus bars adjacent in the first direction, where the width of the first conductor portion is greater than the thickness thereof, and when viewed from the third direction, the first conductor portions of the first and second bus bars are spaced apart from each other by a certain distance in the second direction.