Battery Stack Fastening Structure for Swelling-Induced Bolt Slippage
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Solution Overview
Problem
Bolt slippage occurs at the fastening parts between the bind bar and the end plate due to the swelling and contraction of battery cells, compromising the fixed state and safety of the battery stack.
Innovation Solution
A power source device with a fastening member design that includes a fastening body and a coupling piece with a height difference, and a metallic third cover that reinforces the upper surface to absorb swelling and contraction, preventing bolt slippage and maintaining a reliable fixed state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bind bar is made with high rigidity to cope with battery cell swelling, then the swelling resistance is improved, but bolt slippage occurs at the fastening part between the bind bar and end plate
Solution Approach 1:
The bind bar is designed with flexible portions (bent portions) that can deform elastically to accommodate battery cell swelling while maintaining the fastening connection. This flexibility prevents bolt slippage by allowing the bind bar to adapt to volume changes without losing its clamping force on the battery stack.
Solution Approach 2:
The bind bar transitions from a rigid structure to a dynamic structure with bent portions that can change shape in response to battery swelling. The flexible portions act as mechanical elements that absorb dimensional changes, maintaining reliable fastening while accommodating the dynamic swelling behavior of battery cells during charge-discharge cycles.
2Quantity of substance
If the battery cell capacity is increased to meet higher demand, then the energy storage is improved, but the swelling amount increases
Solution Approach 1:
The bind bar incorporates flexible portions that can elastically deform to accommodate the increased swelling volume associated with higher capacity battery cells. These bent portions act as mechanical buffers that absorb the dimensional changes without transmitting excessive stress to the fastening connections.
Solution Approach 2:
The flexible portions of the bind bar are pre-configured to provide cushioning against battery swelling before the swelling occurs during battery operation. This beforehand cushioning capacity allows the bind bar to absorb the expected volume expansion of high-capacity cells without compromising the structural integrity or fastening reliability.
Data Source
AI summary
Power source device includes: battery stack in which a plurality of battery cells are stacked; a pair of end plates that each have a plate shape having a main surface and a side surface intersecting the main surface, are formed with plate screw hole on the side surface, and are arranged on both side end surfaces of battery stack; a plurality of fastening members that are extended in stack direction of the battery stack, have fastening screw holes opened at ends, and couple end plates to each other; and bolt that is inserted into fastening screw hole of each fastening member and plate screw hole of end plate to fix the fastening member to end plate. The fastening member includes plate-shaped fastening body, intermediate part obtained by bending both ends of fastening body, and coupling piece obtained by bending an end of intermediate part far from fastening body to provide a height difference from fastening body and form fastening screw hole.