Adjustable Battery Pack Plates for Cell Swelling Preload Control
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Solution Overview
Problem
Existing battery packs face challenges in maintaining optimal preload and reducing mechanical stress on the containment frame due to the progressive thickness increase of lithium cells, leading to potential oversizing and increased weight, which affects vehicle performance.
Innovation Solution
The battery pack design allows the retaining plates to move apart along the axis to accommodate the increasing cell thickness, using manual or automatic adjustment devices to maintain constant preload and reduce stress, with optional lip elements for sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the containment frame is oversized to accommodate cell thickness increase, then the mechanical stress on the frame is reduced, but the weight of the battery pack increases
Solution Approach 1:
The retaining plates are designed to move relative to each other along the axis A, transforming the static containment structure into a dynamic one. This allows the distance between plates to increase as cells expand, maintaining constant preload without requiring an oversized frame, thus avoiding increased battery pack weight while managing mechanical stress
2Stability of the object's composition
If the distance between retaining plates is fixed, then the structural integrity is maintained, but the preload on cells becomes inconsistent during cell expansion
Solution Approach 1:
The adjustable distance between retaining plates allows the structure to adapt to cell expansion while maintaining consistent preload. The plates can move to accommodate thickness increase, ensuring reliable electrical contact and preventing damage throughout the battery pack lifecycle
Solution Approach 2:
Adjustment devices act as intermediaries between the retaining plates, enabling controlled movement and distance adjustment. These devices facilitate the dynamic adaptation of the containment structure to cell expansion while maintaining structural integrity and preload consistency
3Reliability
If adjustment devices are added to move retaining plates, then preload consistency is improved, but the device complexity increases
Solution Approach 1:
The adjustment devices are designed to be manually operable without requiring complex automated systems. The simple manual adjustment mechanism allows technicians to adapt the plate distance to cell expansion, achieving preload consistency without adding complex automated control systems
Solution Approach 2:
The system allows for simple parameter changes in the distance between retaining plates through manual adjustment. This enables adaptation to cell expansion by changing the geometric parameter of plate separation, maintaining preload consistency without complex mechanisms
Data Source
AI summary
Battery pack for a road vehicle with electric propulsion; wherein the battery pack comprises: a plurality of planar electrochemical cells arranged in pack along an axis A; and a support structure that comprises two plates opposite along the axis and parallel to the cells. The two plates define the housing volume for the cells. The cells at the beginning of life are housed in the support structure with an initial preload along the axis that generates a corresponding initial axial stress acting on the plates. Each cell comprises two flat faces orthogonal to the axis A and a thickness along the axis A that gradually increases over the life of the battery pack. The plates are configured to move away from each other along the axis A such that an increase in cell thickness does not result in a corresponding progressive increase in the axial stress acting on the plates.