Fuse Unit Coupling Portions Reinforcement Heat Shrinkage
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Solution Overview
Problem
Conventional fuse units experience stress concentration and reduced mechanical strength in fusible parts due to heat shrinkage of insulating resin portions, which affects the fusing property and structural integrity.
Innovation Solution
Incorporating reinforcement portions with a lower heat shrinkage rate and higher strength than the insulating resin into the bus bar, these reinforcement portions are used as insert components during insert molding to form coupling portions, reducing heat shrinkage and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the insulating resin portion is formed by insert molding, then the mechanical strength of the coupling portion is improved, but heat shrinkage produces stress concentration on the bus bar
Solution Approach 1:
The invention changes the material parameter of the coupling portion by using a resin with a lower heat shrinkage rate. This parameter change reduces the heat shrinkage effect during molding, thereby minimizing stress concentration on the bus bar while maintaining mechanical strength of the coupling portion.
Solution Approach 2:
The invention applies local quality by differentiating the heat shrinkage rate of different parts of the insulating resin portion. The coupling portion uses a resin with lower heat shrinkage rate, while other portions may use different materials, optimizing both stress distribution and mechanical strength in specific critical areas.
2Strength
If the thickness dimension of the coupling portion is increased, then the mechanical strength of the coupling portion is improved, but the amount of resin shrinkage is increased, leading to greater stress concentration
Solution Approach 1:
The invention changes the material parameter by selecting a resin with inherently lower heat shrinkage rate. This allows the coupling portion to achieve the required mechanical strength without increasing thickness, thereby avoiding the associated resin shrinkage and stress concentration problems.
Solution Approach 2:
The invention optimizes the geometric shape of the coupling portion to reduce stress concentration. By carefully designing the contours and transitions, the structure achieves high mechanical strength with minimized thickness, reducing the volume of resin and associated shrinkage effects.
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
Minimizes stress concentration and increases mechanical strength of fusible parts and coupling portions, ensuring consistent fusing properties and improved structural integrity while reducing the need for additional reinforcement members.
Implementation Method 1
a stress resulting from heat shrinkage produced after the resin molding acts on the bus bar 51
Data Source
AI summary
A fuse unit includes: a bus bar including a plurality of fusible parts interposed between a power supply side terminal and a plurality of load side terminals; and an insulating resin portion formed by insert molding using the bus bar as an insert component. The insulating resin portion includes: first and second resin portions respectively arranged at peripheries on the sides of the power supply side terminal and the load side terminals with respect to the fusible parts; and a plurality of coupling portions coupling the first resin portion and the second resin portion in a position outside each of the fusible parts. Each of the coupling portions is formed such that a reinforcement portion having a lower heat shrinkage rate than the insulating resin portion and having a higher strength than the insulating resin portion is an insert component. The reinforcement portion is provided using the bus bar.