Battery Pack Assembly Using Pressurized Cover Members for Shock Reliability
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Solution Overview
Problem
Conventional battery pack assembly methods lack sufficient reliability against shock, as the strip members used to suppress movement of cell sub-assemblies are insufficient, leading to potential displacement and adverse effects on battery performance.
Innovation Solution
A method involving a battery pack assembly where a cell group of stacked unit cells is pressurized using first and second cover members, with the second cover members intersecting the stacking direction and electrode tab direction to enhance stability and prevent movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strip members are used to suppress movement of cell sub-assemblies, then some movement suppression is achieved, but the suppression is insufficient and cell sub-assemblies can still move under external shock forces
Solution Approach 1:
The battery pack structure is segmented into multiple functional components: first cover members for pressurizing the cell group, second cover members for lateral support, and buffer members for shock absorption. This segmentation allows each component to specialize in a specific function, with the buffer members specifically dedicated to absorbing orthogonal shocks and preventing cell sub-assembly displacement.
Solution Approach 2:
The invention changes the physical state and positioning parameters by pressurizing the cell group in the stacking direction using the first cover members, which creates frictional forces that stabilize the cell sub-assemblies. Additionally, buffer members are positioned between the cell group and second cover members to alter the mechanical response to orthogonal shocks.
2Stability of the object's composition
If cell sub-assemblies are tightly secured to prevent movement, then stability is improved, but assembly complexity and difficulty increase
Solution Approach 1:
The first cover members are designed to apply pressurizing force to the cell group, creating dynamic frictional forces that adaptively stabilize the cell sub-assemblies during normal operation and under shock conditions. This dynamic stabilization mechanism is simpler than rigid mechanical fastening systems.
Solution Approach 2:
Buffer members are introduced as intermediary elements between the cell group and second cover members. These buffer members simplify the assembly structure by providing a straightforward mechanical interface that absorbs shocks without requiring complex locking or fastening mechanisms.
3Reliability
If pressurizing force is applied to the cell group, then frictional forces increase and movement is suppressed, but the assembly process becomes more complex
Solution Approach 1:
The first cover members perform multiple functions simultaneously: they enclose the cell group, apply pressurizing force to generate stabilizing frictional forces, and serve as mounting structures for the buffer members. This merging of functions reduces the number of separate components and simplifies the overall assembly process.
Solution Approach 2:
The cell group is pressurized during the assembly process itself, rather than requiring a separate pressurization step. The first cover members are installed in a pressurized state, which maintains the frictional forces and stability throughout subsequent assembly operations and battery operation.
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 proposed method significantly improves shock reliability by maintaining pressurizing force on the cell group, ensuring strong frictional forces and stable electrode connections, thus enhancing battery performance and preventing displacement during orthogonal shocks.
Implementation Method 1
maintaining pressurizing force on the cell group, ensuring strong frictional forces
Implementation Method 2
a pair of second cover members is disposed on the outer side of both ends of the cell group in a direction that intersects with the stacking direction
Implementation Method 3
the pair of first cover members and the pair of second cover members are welded in a state in which pressurizing force is imparted to the cell group
Data Source
AI summary
A method for assembling a battery pack having a cell group includes stacking the plurality of the unit cells such that distal end portions of the electrode tabs of the unit cells are bent along a stacking direction, disposing a pair of first cover members both ends of the unit cells in the stacking direction, disposing a pair of second cover members on both ends of the unit cells in a direction that intersects with the stacking direction, welding the first and second cover members while the cell group is pressurized using the first cover members. The welding of the first cover members and the second cover members is performed prior to electrically connecting the unit cells by a bus bar. The method further includes laser-welding the bus bar to distal end portions of the electrode tabs after the first cover members and the second cover members are welded.