Battery Module End Plate Locking Hole Deformation Space
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Solution Overview
Problem
High-energy-density prismatic battery cells in battery modules experience significant dimensional changes during charge and discharge, leading to high cell reaction forces that exert excessive shear stress on fixing bolts, making it difficult to suppress expansion while maintaining a lightweight and cost-effective design.
Innovation Solution
Incorporating locking holes with deformation spaces in end plates for fixing bolts, allowing the bolts to deform and distribute the cell reaction force through bind bar tension and frictional resistance, thereby reducing the shear force acting on the bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-energy-density prismatic battery cells are adopted to increase energy density, then energy density per volume and per weight is improved, but dimensional change during charge and discharge increases causing greater cell reaction force
Solution Approach 1:
The locking hole geometry is changed to include a deformation space, transforming the rigid connection into a flexible one that accommodates dimensional changes. This parameter change in the hole structure allows the fixing bolt to deform elastically, absorbing the cell reaction force without compromising the high-energy-density battery cells
2Stability of the object's composition
If fixing bolts are used to secure end plates to chassis, then structural stability is improved, but shear force on bolts increases due to cell reaction force
Solution Approach 1:
The locking hole is designed with a deformation space that changes the mechanical parameter of the bolt connection from rigid to flexible. This allows the bolt to deform elastically under cell reaction force, reducing shear stress while maintaining structural stability through the combined action of bolt tension and friction
Solution Approach 2:
The deformation space in the locking hole acts as a pre-designed cushioning mechanism. When cell reaction force occurs, the bolt can deform within this space, absorbing the shock and reducing peak shear forces on the bolt before they reach critical levels
3Strength
If multiple thick fixing bolts are used to withstand shear force, then strength is improved, but device complexity and weight increase
Solution Approach 1:
The locking hole geometry is modified to include a deformation space, changing the mechanical behavior of the bolt from rigid to flexible. This allows standard-sized bolts to withstand cell reaction forces through elastic deformation and friction, eliminating the need for multiple thick bolts and reducing overall device complexity
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 design effectively reduces the shear force on fixing bolts, enabling a smaller, lighter, and more cost-efficient battery module that can manage the cell reaction forces without the need for multiple thick bolts, thus facilitating weight reduction and cost optimization.
Implementation Method 1
a deformation space that allows deformation of the fixing bolt when cell reaction force of the battery stack is caused
Implementation Method 2
distribute the cell reaction force through bind bar tension and frictional resistance
Data Source
AI summary
A pair of end plates disposed respectively at end faces of a battery stack are connected by bind bars and apply pressure to the battery stack to immobilize the battery stack. Each of the end plates includes a locking hole extending along a surface of the end plate. The end plate is fixed to a base plate by a fixing bolt inserted through the locking hole. The locking hole includes a deformation space that allows deformation of the fixing bolt when cell reaction force of the battery stack is caused.