Battery Pack Sealing Structure for Vibration Resistance
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Solution Overview
Problem
Battery packs used in electric vehicles and bicycles face sealing failures and electrolyte leakage due to vibration, as existing fixation methods deform the sealing portions and compromise insulation resistance.
Innovation Solution
A battery pack design featuring film-casing batteries with a sealing portion formed by synthetic resin layers, where the sealing surface is parallel to the unit battery stacking surface, and a reinforcing member is added with a fixing tape to maintain hermetic sealing and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tape is obliquely-wound from the base plate to the unit batteries for fixation, then the unit batteries are secured against displacement due to vibration, but the sealing portion of the unit battery is deformed, degrading insulation resistance and causing liquid leakage
Solution Approach 1:
A buffer member is introduced as an intermediary element between the fixing tape and the unit battery sealing portion. This buffer member absorbs the mechanical stress and deformation caused by the oblique winding of the fixing tape, preventing direct transmission of harmful forces to the sealing portion while maintaining effective fixation of the unit batteries against vibration-induced displacement
Solution Approach 2:
The buffer member is positioned in advance at the sealing portion of the unit battery to provide preemptive protection. By placing this cushioning element before the fixing tape is applied, the sealing portion is预先 protected from deformation that would otherwise occur during the fixation process and throughout the operational vibration cycles
2Reliability
If the sealing surface is made parallel to the unit battery stacking surface, then the sealing characteristics are maintained and insulation resistance is preserved, but the fixation structure becomes more complex requiring additional components
Solution Approach 1:
The buffer member serves as a mediator that enables the sealing surface to remain parallel to the unit battery stacking surface while still allowing for effective fixation. This intermediary component absorbs the geometric mismatch between the oblique fixing tape and the parallel sealing surface, maintaining sealing integrity without requiring complex alternative fixation structures
3Object-affected harmful factors
If the buffer member is added between the fixing tape and sealing portion to prevent deformation, then sealing integrity is maintained, but the device complexity and manufacturing steps increase
Solution Approach 1:
The buffer member is designed to perform multiple functions simultaneously: it acts as a cushioning element to prevent sealing deformation, serves as a structural support between the fixing tape and unit battery, and provides a mounting surface for the fixing tape. This multi-functionality reduces the need for additional separate components, offsetting the complexity increase with functional consolidation
Data Source
AI summary
To provide a battery pack less subject to vibration, shock, or the like and stable in characteristics.A battery pack includes a unit battery obtained by accommodating, in a casing film, a battery element in which positive and negative electrodes are stacked via separators, the unit battery having a sealing portion obtained by sealing opposing synthetic resin layers formed on inner surface of the casing film; and a lithium ion secondary battery stacked body obtained by stacking a plurality of the unit batteries and winding a fixing tape therearound. A sealing surface of the sealing portion is substantially parallel to a unit battery stacking surface, and an end surface of the sealing portion is brought into contact with the fixing tape.