Battery Pack Cell Restraint Using Spring Plates and Unequal Pins
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Solution Overview
Problem
Battery packs face issues with cell motion relative to the housing due to external and internal factors like vibration and prismatic cell growth, leading to potential cell damage and reduced longevity, which affects operability and reliability.
Innovation Solution
The battery pack incorporates spring plates between the cell array and the container to restrain motion in the direction parallel to the cell stacking, and pairs of restraining pins with unequal lengths and stiffnesses to control motion in orthogonal directions, ensuring cell stack forces remain within a predetermined range and accommodating cell growth without applying excessive force to the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid cell restraint structures are used to prevent cell motion, then cell stability is improved, but cell stress and damage risk increase
Solution Approach 1:
The patent changes the mechanical parameters of the restraint structure by using spring plates with controlled stiffness and unequal-length pins with different compliance characteristics. This allows the structure to provide restraint while accommodating cell expansion through elastic deformation, reducing peak stresses on cells during motion restraint.
Solution Approach 2:
The restraint mechanism combines multiple materials with different mechanical properties - spring plates with specific elasticity, pins with varying stiffness, and housing materials - to create a composite system that balances rigidity for motion prevention with compliance for stress reduction.
2Reliability
If cell motion is completely restrained, then operability is improved, but adaptability to cell growth decreases
Solution Approach 1:
The restraint structure transitions from a static rigid system to a dynamic compliant system. The spring plates and unequal-length pins allow controlled movement and adaptation as cells grow, while maintaining operational reliability through continuous contact and force distribution.
Solution Approach 2:
The restraint mechanism is segmented into multiple independent elements (spring plates, individual pins of different lengths) rather than a single rigid structure. This segmentation allows differential movement and adaptation to non-uniform cell growth while maintaining overall restraint.
3Stability of the object's composition
If rigid housing structures are used to maintain dimensional stability, then housing stability is improved, but seal integrity under cell expansion decreases
Solution Approach 1:
The spring plates and pins act as intermediary elements between the rigid housing and expanding cells. These intermediaries absorb expansion forces through elastic deformation, protecting the seal interface from excessive stress while maintaining housing dimensional stability.
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
This solution effectively reduces cell stress, maintains dimensional stability of the housing, enhances the seal integrity, and improves battery pack reliability and longevity by preventing particle and moisture ingress while accommodating cell expansion.
Implementation Method 1
the battery pack further includes a spring element that is configured to restrain motion the cells in a second direction that is perpendicular to the first direction
Data Source
Figure 1
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Figure 4
AI summary
A battery pack (1) includes a housing (2) and an array (40) of electrochemical cells (80) disposed in the housing (2). The housing (2) includes a container (3) and a lid (30) that closes an open end of the container (3). The container (3) has a base (4), a sidewall (8) that surrounds the base (4), and a spring plate (110) disposed inside the sidewall (8) between the cells (80) and the sidewall (8). The spring plate (110) is free standing within the container (3) and applies a spring force to the cell array (40) that restrains the cells (80) along an axis normal to the surface of the spring plates (110). The lid (30) includes inwardly-protruding pins (50, 60) that further restrain the cells (80) within the housing (2).