Battery Pack Cell Spacers With Variable Thickness for Lower Frame Stress
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Solution Overview
Problem
Existing battery packs in electrically powered vehicles experience increased mechanical stress due to the progressive thickness increase of cells, leading to oversized frames and increased weight, which affects vehicle performance.
Innovation Solution
Implementing planar intermediate bodies with a differentiated thickness and shape that generate a smaller reaction force and less steep gradient during cell thickness expansion, allowing the frame to be sized more lightly and reducing overall weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If planar intermediate bodies with constant thickness are used between cells, then the cells are separated and compensated for thickness increase, but the reaction force generated against the frame increases with a non-linear development and greater gradient, requiring an oversized frame
Solution Approach 1:
The intermediate body is designed with non-uniform thickness distribution, having greater thickness at the edges and smaller thickness at the center. This local variation in geometry allows different regions of the intermediate body to compress at different rates, creating a more linear force development profile that reduces the peak reaction force transmitted to the frame, thereby allowing for a lighter frame structure.
Solution Approach 2:
The invention changes the geometric parameter of the intermediate body from constant thickness to variable thickness. By modifying the thickness parameter across different locations of the intermediate body, the compression characteristics are altered to produce a more linear force-displacement relationship, reducing the gradient of force increase during cell expansion and enabling a lighter frame design.
2Reliability
If the frame is sized to withstand the stress from cell expansion, then the battery pack can accommodate cell thickness increase, but the battery pack weight increases due to the oversized frame
Solution Approach 1:
The intermediate body with non-uniform thickness distribution provides localized compression resistance where needed (at the edges) while allowing more compliant behavior in the center. This localized quality approach maintains the structural integrity and durability of the battery pack during cell expansion while reducing the overall reaction force transmitted to the frame, enabling a lighter yet still reliable battery pack design.
Solution Approach 2:
The intermediate body acts as a mediator between the expanding cells and the frame structure. By introducing this intermediate element with optimized thickness distribution, the force transmission path is modified to reduce peak stresses reaching the frame, thereby maintaining battery pack durability through controlled force distribution while reducing the weight penalty of an oversized frame.
3Ease of manufacture
If planar separators with constant thickness are used, then the structure is simple to manufacture, but the force generated against the cells has a non-linear development with greater gradient during compression
Solution Approach 1:
The intermediate body is designed with locally varied thickness properties, having different thickness values at different locations (thicker at edges, thinner at center). This local quality differentiation modifies the compression behavior to create a more linear force development profile, reducing the force gradient during cell expansion while remaining manufacturable through conventional molding techniques.
Solution Approach 2:
The geometric parameter of thickness is changed from a constant value to a spatially varying parameter across the intermediate body. This parameter change transforms the compression characteristics, producing a more linear force-displacement relationship that reduces the gradient of force increase during cell expansion, while the overall simple geometry maintains ease of manufacture.
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 solution effectively reduces mechanical stress on the frame by minimizing the force transmitted, enabling a lighter and more efficient battery pack design without altering initial dimensions or materials, thus enhancing vehicle performance.
Implementation Method 1
The planar intermediate body (51) is configured to compress during the progressive increase in thickness of the cells (C)
Implementation Method 2
said planar intermediate body being made of an elastomeric material
Data Source
AI summary
A battery pack for an electrically powered road vehicle includes: a plurality of planar electrochemical cells arranged in a pack along an axis A; a box-shaped support structure housing the cells; wherein each cell comprises two flat faces orthogonal to the axis A and a thickness s1 along the axis A progressively increasing during the life of the battery pack; wherein between each pair of adjacent cells there is a planar intermediate body in contact with the flat faces of the cells; wherein each planar intermediate body is configured to compress during the progressive increase in thickness s1 of the cells; wherein each planar intermediate body comprises a flat face orthogonal to the axis A contacting the flat face of a first cell of the pair of cells; wherein at least one of the planar intermediate bodies comprises portions with a differentiated thickness s2, s3 along the axis A.