Tubular Battery Pack Fastening Structure for Vibration Stability
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Solution Overview
Problem
Conventional battery packs with cylindrical batteries arranged in a tubular case face issues with vibration, where the internal core block can move relative to the outer case, requiring high torque for waterproofing, which can damage the case and increase manufacturing costs due to thick molding and additional screw processing.
Innovation Solution
A battery pack design featuring a core block with battery cells stacked in a tubular case, where the covering parts are fastened through the core block using a fastening member, eliminating the need for protrusions on the case and allowing for a thinner, lighter construction with reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If setscrews are fastened with large torque to provide waterproof structure, then waterproofing is improved, but protrusion may be twisted locally and case body may be damaged
Solution Approach 1:
The case body is divided into two functional parts: the protrusion for mechanical fastening and the threaded hole for screw engagement. This segmentation allows the protrusion to be thin and lightweight while the threaded hole provides the necessary strength for waterproof fastening, resolving the contradiction between waterproofing reliability and protrusion integrity.
Solution Approach 2:
The threaded hole acts as an intermediary element between the protrusion and the setscrew. Instead of directly fastening the setscrew to the protrusion (which would require large torque and risk damaging the protrusion), the setscrew engages with the threaded hole, distributing the fastening load and protecting the protrusion from excessive stress while maintaining waterproofing.
2Strength
If case body is molded thickly to prevent damage, then strength is improved, but external size increases and manufacturing cost increases
Solution Approach 1:
The case body structure is segmented into a thin-walled tubular body and a separately formed threaded hole. This allows the main case body to remain thin for reduced volume and weight, while the localized threaded hole provides the necessary strength for fastening without requiring the entire case body to be thick-walled.
Solution Approach 2:
The threaded hole is created as a localized feature with enhanced structural properties only where needed for fastening. This local quality enhancement provides sufficient strength for waterproof mounting without requiring the entire case body to be molded thickly, thus maintaining overall compactness and reducing manufacturing cost.
3Ease of operation
If protrusions are provided inside surfaces of case body for fastening, then fastening capability is improved, but device complexity increases due to additional screw processing
Solution Approach 1:
The protrusion and threaded hole are merged into a single integrated feature of the case body. The threaded hole is formed as part of the protrusion structure, combining the fastening function (protrusion) with the screw engagement function (threaded hole) into one unified element, simplifying the overall structure and eliminating the need for separate fastening components.
Solution Approach 2:
The protrusion with integrated threaded hole serves multiple functions: it provides mechanical support, enables screw fastening, ensures waterproofing, and maintains structural integrity. This multi-functional design eliminates the need for separate fastening mechanisms, reducing device complexity while improving ease of operation.
Data Source
AI summary
A core block accommodated in an outer case is effectively prevented from moving relative to the outer case. A main tubular part is thin and light at low cost, and openings at both ends of the main tubular part are precisely covered with covering parts. A battery pack includes: a core block including battery blocks stacked and interconnected each including battery cells arranged at predetermined positions in a battery holder; an outer case including a main tubular part with a tubular shape having the core block inserted therein, and a pair of covering parts covering openings at both ends of the main tubular part; and a fastening member fastening the covering parts to main tubular part from both sides of main tubular part. The core block is accommodated in an outer case such that the battery blocks are stacked in an axial direction of main tubular part. The fastening member fastens the covering parts through the core block.