Electric Junction Box with Resin Panel Joints for EMI Shielding
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Solution Overview
Problem
The existing electric junction boxes for automobiles face challenges in reducing cost and weight while maintaining effective Electro-Magnetic Interference (EMI) shielding, as they require thick metal case members to achieve the necessary shielding effect, which increases production costs and weight.
Innovation Solution
The electric junction box incorporates conductive panels and panel joints made of synthetic resin at the joining areas, allowing for thinner walls and reduced weight, with the case members being divided and combined to form a receiving space, and featuring openings and combining pieces to enhance water-sealing and mounting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If thick metal case members are used to achieve required EMI shielding effect, then EMI shielding performance is improved, but weight and production cost increase
Solution Approach 1:
The case members are divided into multiple sections (front case member, rear case member, side case members) that can be assembled together. This segmentation allows each part to be optimized independently and reduces the overall material required while maintaining shielding effectiveness through proper positioning and spacing of conductive elements.
Solution Approach 2:
The patent uses composite construction combining metal case members for EMI shielding with synthetic resin panel joints for structural connection. This composite approach allows the metal portions to provide electromagnetic shielding while the resin portions reduce overall weight and cost, achieving the required shielding effect without using solid thick metal throughout the entire structure.
2Object-affected harmful factors
If thick metal case members are used to achieve required EMI shielding effect, then EMI shielding performance is improved, but production cost increases
Solution Approach 1:
Dividing the case into multiple assembleable sections reduces manufacturing complexity and allows for more efficient production. Each segment can be manufactured using standard sheet metal forming processes rather than requiring thick solid metal blocks, reducing material costs and manufacturing difficulty.
Solution Approach 2:
Using synthetic resin for panel joints instead of solid metal connections reduces material costs while maintaining structural integrity. The resin components can be molded using cost-effective injection molding processes, replacing expensive metal fastening hardware and reducing overall production cost.
3Weight of stationary object
If case members are divided and combined to form receiving space, then weight and cost are reduced, but water-sealing performance may be compromised
Solution Approach 1:
Synthetic resin panel joints serve as intermediary elements between the metal case members, providing both structural connection and water-sealing functionality. These panel joints act as mediators that bridge the gaps between divided case sections while preventing water penetration, solving both the weight reduction and sealing requirements simultaneously.
Solution Approach 2:
The synthetic resin panel joints function as flexible sealing elements that can conform to the mating surfaces of the metal case members. This flexibility allows the panel joints to effectively seal the joints between divided case sections, preventing water ingress while maintaining the lightweight divided structure.
4Weight of stationary object
If synthetic resin panel joints are used at panel joining areas, then weight and cost are reduced, but EMI shielding continuity may be affected
Solution Approach 1:
The synthetic resin panel joints are positioned and designed to bridge gaps between metal case members in a way that maintains EMI shielding continuity. The panel joints act as intermediaries that connect the metal sections while the overall case design ensures electromagnetic shielding effectiveness is preserved through proper spacing and positioning of conductive elements.
Solution Approach 2:
The case structure is designed with local quality variations where metal case members provide EMI shielding at critical areas while synthetic resin panel joints are used for structural connection and sealing. This localized approach optimizes each material's properties where needed - metal for shielding where electromagnetic fields are present, resin for structural and sealing functions where shielding is less critical.
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 achieves a lighter weight and lower production costs while maintaining the required EMI shielding effect, with improved water-sealing performance and reduced boundary areas for uniform pressure application.
Implementation Method 1
an electric unit (2) and a shield case (3) receiving the electric unit (2), wherein the shield case (3) includes electric conductive panels (33) and a panel joint (34) made of synthetic resin to be provided at a panel joining area
Data Source
AI summary
Providing an electric junction box, which can reduce a cost and the weight with maintaining shield effect, in the electric junction box including an electric unit and a shield case, a panel joint at a panel joining area of a conductive panel is formed with synthetic resin. The shield case can be formed with a thin sheet metal by press forming. The electric unit is received in the shield case, so that the electric junction box can maintain shield effect.