Battery Pack Aperture Seal Assembly for Vacuum Retention
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Solution Overview
Problem
Vehicle battery packs face challenges in maintaining a vacuum seal during shipping due to apertures for fasteners, which compromise the integrity of the vacuum and expose the interior to contamination.
Innovation Solution
A seal assembly comprising a grommet, compression limiter, and plug is used to close apertures in the battery pack cover, allowing for vacuum retention and fastener passage, featuring a grommet with distinct thickness portions and a compression limiter to manage mounting forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If apertures are provided in the cover for fastener passage, then the battery pack can be mounted to the vehicle, but the vacuum seal is compromised and contamination risk increases
Solution Approach 1:
The aperture sealing function is segmented into distinct components: a grommet that provides the seal, a compression limiter that controls mounting forces, and a plug that maintains vacuum. This segmentation allows each component to perform its specific function optimally while working together to resolve the contradiction between mounting capability and vacuum integrity.
Solution Approach 2:
The grommet acts as an intermediary element between the aperture and the vacuum environment. It provides a sealant member that bridges the opening, allowing fasteners to pass through while maintaining the vacuum seal. The compression limiter serves as another intermediary that mediates between the mounting structure and the grommet, controlling the forces applied during installation.
2Reliability
If a seal is provided to close the aperture, then vacuum is maintained, but fastener passage is blocked
Solution Approach 1:
The seal assembly exhibits local quality by having different portions with distinct properties: the grommet provides sealing at the aperture edges, the compression limiter provides structural support and force distribution, and the plug provides vacuum maintenance. This localized differentiation allows the assembly to simultaneously maintain vacuum integrity and permit fastener passage through the central opening.
Solution Approach 2:
The seal assembly uses a nested structure where the plug is positioned within the grommet's central opening, and the compression limiter surrounds portions of the grommet. This nesting allows multiple functions to be integrated in a compact arrangement, with the innermost plug providing vacuum sealing while outer components provide structural support and fastener guidance.
3Reliability
If compression force is applied to secure the grommet, then the seal is tightened, but the grommet may be over-compressed and damaged
Solution Approach 1:
The compression limiter is designed to provide beforehand cushioning by limiting the maximum compression force that can be applied to the grommet. The limiter's geometry and material properties are selected to absorb excess compression forces, preventing over-compression damage to the grommet while still allowing sufficient compression to achieve proper sealing.
Solution Approach 2:
The compression limiter changes the compression parameter by providing a controlled resistance to compression forces. It transforms the compression force profile, allowing gradual compression during installation while preventing sudden or excessive force application. This parameter control ensures the grommet is compressed enough to seal properly without exceeding its elastic limits.
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
The seal assembly effectively maintains a vacuum and prevents contamination while enabling secure mounting of the battery pack to the vehicle, ensuring a sealed environment during transport and installation.
Implementation Method 1
The grommet is formed from an elastic material
Implementation Method 2
the plug is formed from a self-healing pierceable elastic material
Data Source
AI summary
A battery pack for a vehicle, in accordance with a non-limiting example, includes a housing including a base, a plurality of side walls and a cover extending across the plurality of side walls. The cover includes an outer surface portion and an inner surface portion, and an aperture extending through the outer surface portion and the inner surface portion. A grommet having a central opening is arranged in the aperture. The grommet includes a first portion engaging the outer surface portion, a second portion engaging the inner surface portion, and a connecting portion joining the first portion and the second portion. A compression limiter having a passage is mounted in the central opening of the grommet. The compression limiter includes a flange surrounded by the first portion of the grommet and a support portion extending through the connecting portion to the second portion of the grommet.