Dual-Lid Battery Pack Structure for High Volumetric Energy Density
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Solution Overview
Problem
Conventional battery packs with tubular case bodies require fixing protrusion ridges on the inner or outer surfaces to secure the lid, which restricts the inner volume and reduces volumetric energy density.
Innovation Solution
A battery pack design that eliminates the need for fixing protrusion ridges by using an inner lid connected to the inner surface of the case body and an outer lid fixed to the inner lid, allowing the case body to be efficiently mass-produced while maintaining a high volumetric energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixing protrusion ridges are provided on the inner surface of the case body to fix the lid, then the lid can be securely fixed, but the inner volume of the battery pack is restricted
Solution Approach 1:
The lid is divided into two separate parts: an inner lid that contacts the case body opening and an outer lid that is fixed to the inner lid. This segmentation allows the fixing structure to be integrated into the lid assembly rather than requiring protrusions on the case body, thereby preserving the inner volume while maintaining secure fixation.
Solution Approach 2:
The inner lid is inserted into the case body opening, and the outer lid is fixed onto the inner lid, creating a nested structure. This nested arrangement allows the fixing mechanism to be contained within the lid assembly itself, eliminating the need for case body protrusions and preserving maximum inner volume.
2Volume of stationary object
If fixing protrusion ridges are provided on the outer surface of the case body to prevent restriction of inner volume, then the inner volume is preserved, but the outer shape of the battery pack is enlarged
Solution Approach 1:
By segmenting the lid into inner and outer lids, the fixing function is transferred to the lid assembly rather than requiring external protrusions on the case body. This keeps the outer shape compact while preserving inner volume.
Solution Approach 2:
The fixing mechanism is moved from the case body (three-dimensional protrusions) to the lid assembly (two-dimensional fixing surface on the inner lid). This dimensional shift allows fixation without adding external volume to the case body.
3Productivity
If a tubular case body is used for efficient mass production, then manufacturing efficiency is improved, but the opening of the case body requires complex fixing structures to secure the lid
Solution Approach 1:
The lid is segmented into inner and outer lids with distinct functions. The inner lid provides a simple fixing interface with the tubular case body opening, while the outer lid is fixed to the inner lid. This segmentation simplifies the fixing structure compared to conventional single-lid designs, making it compatible with efficient tubular case body mass production.
Solution Approach 2:
The fixing function is extracted from the case body and transferred to the lid assembly. The inner lid includes a fixing structure that directly engages with the case body opening, eliminating the need for complex case body modifications and simplifying the overall fixing mechanism for mass production.
Data Source
AI summary
A battery pack according to an aspect of the present disclosure includes a battery module and an external case accommodating the battery module therein. The external case includes: a case body having a tubular shape having an opening; and a lid part closing the opening of the case body. The lid part includes: an inner lid connected to the opening of the case body; and an outer lid fixed to the inner lid and closing the opening of the case body. The inner lid is connected to an inner surface of the case body at the opening of the case body. The outer lid is fixed to an outer surface of the inner lid.