Insert-Molded Terminal Seal Structure for Resin Crack Control
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Solution Overview
Problem
The power storage device faces issues with stress generation and cracking in the resin member due to thermal expansion differences between the case member, terminal member, and resin member, leading to reduced airtightness during thermal cycles.
Innovation Solution
The power storage device incorporates a terminal member with encircling roughened portions and a resin member that includes a terminal seal portion and a stress reducing portion. The terminal seal portion adheres to the first roughened portion to maintain airtightness, while the stress reducing portion, which can contain cracks, adheres to the second roughened portion to reduce stress in the terminal seal portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin member is used to hermetically fix the terminal member to the case member, then airtightness is improved, but stress concentration and cracking occur in the resin member due to thermal expansion differences
Solution Approach 1:
The resin member is divided into two functional portions: a terminal seal portion for hermetic sealing and a stress reducing portion for stress relief. This segmentation allows each portion to optimize its function - the terminal seal portion maintains airtightness while the stress reducing portion prevents cracking by absorbing thermal stress through its larger volume and adherence to the second roughened portion
Solution Approach 2:
Different regions of the resin member are given different functional qualities. The terminal seal portion is designed for hermetic sealing with adherence to the first roughened portion, while the stress reducing portion is designed for stress absorption with adherence to the second roughened portion. This local differentiation resolves the contradiction by assigning specific roles to specific regions
2Productivity
If the resin member is integrally molded with the case member and terminal member, then manufacturing efficiency is improved, but thermal stress concentration occurs during cooling
Solution Approach 1:
The integrally molded resin member is segmented into two portions with different functions. The stress reducing portion acts as a buffer zone that absorbs thermal stress generated during cooling, preventing stress concentration while maintaining the benefits of integral molding for manufacturing efficiency
Solution Approach 2:
The stress reducing portion is designed in advance to cushion against thermal stress that will occur during cooling. By providing this stress-absorbing structure before thermal cycling occurs, the design prevents cracking while maintaining manufacturing efficiency through integral molding
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 configuration effectively reduces stress in the terminal seal portion, preventing cracking and maintaining high airtightness reliability, even under thermal cycling conditions.
Implementation Method 1
the lid and the terminal member are integrally and hermetically fixed to each other with an insulating resin member by insert molding
Implementation Method 2
a first roughened portion that has a roughened surface and surrounds the terminal member, and a second roughened portion that is spaced apart from the first roughened portion and has a roughened surface
Implementation Method 3
stress due to a difference in thermal expansion may be generated as the temperature decreases in the process of insert molding, because of differences in the coefficient of thermal expansion between the case member (lid), terminal member, and the resin member
Data Source
AI summary
A power storage device includes a case member having a terminal insertion hole, a terminal member inserted through the terminal insertion hole, and a resin member made of an insulating resin material and hermetically adhering to the case member and the terminal member to fix the terminal member to the case member while insulating the members from each other. The terminal member has an encircling band-shaped first roughened portion that has a roughened surface and surrounds the terminal member, and a second roughened portion that is spaced apart from the first roughened portion and has a roughened surface. The resin member is insert-molded integrally with the case member and the terminal member, and has an encircling band-shaped terminal seal portion that hermetically adheres to the first roughened portion, and a stress reducing portion that adheres to the second roughened portion and reduces stress generated in the terminal seal portion.