Battery Module End Plate Recess for Movable Fastening
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Solution Overview
Problem
In conventional battery systems, when battery cells expand due to charging or temperature changes, the end plates can warp, causing stress on the fastening screws and leading to increased electrical resistance due to loosening of the connection between the output line and the electrode terminal.
Innovation Solution
A battery module design with end plates that have recesses to house fastening members in a movable manner, allowing for a gap between the inner side wall of the recess and the fastening member, which prevents loosening of the fastening members and reduces contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the end plates tightly sandwich the battery cells to fix them together, then the battery cells are securely held in the stacked direction, but the end plates become warped when battery cells expand due to charging or temperature rise, causing stress on the fastening screw and loosening of the connection
Solution Approach 1:
The fastening member is designed to be movable within the recess of the end plate along the stacked direction, allowing it to dynamically adjust its position as battery cells expand or contract. This dynamic capability prevents stress accumulation and maintains reliable electrical connection despite thermal expansion or charging-induced volume changes of the battery cells.
Solution Approach 2:
The invention changes the positional parameter of the fastening member within the recess, allowing it to move along the stacked direction. This parameter change enables the fastening member to accommodate variations in battery cell dimensions during charging cycles or temperature changes, preventing warping-induced stress and maintaining connection reliability.
2Reliability
If the fastening screw is tightly fixed to the nut to couple the junction bus bar to the end plate, then the electrical connection is stable, but the fastening screw loosens when the end plate warps due to battery cell expansion
Solution Approach 1:
The fastening member is designed with movable capability within the recess, allowing it to dynamically adjust its position along the stacked direction. This dynamic design maintains stable electrical connection by accommodating end plate warping without causing loosening of the fastening member.
Solution Approach 2:
The recess acts as an intermediary structure between the fastening member and the end plate, providing a movable housing that allows the fastening member to adjust its position. This intermediary structure mediates the conflict between maintaining tight electrical connection and accommodating thermal expansion of battery cells.
3Reliability
If the junction bus bar is fixed to the end plate via the fastening screw, then the electrical connection is secure, but the tightening torque damages the electrode terminal of the battery cell
Solution Approach 1:
The invention extracts the fastening function from the electrode terminal by coupling the junction bus bar to the end plate through the fastening member housed in the recess, rather than directly fastening to the electrode terminal. This separation protects the electrode terminal from damaging tightening torque while maintaining secure electrical connection.
Solution Approach 2:
The end plate with recess serves as an intermediary structure that bears the fastening load, preventing direct transmission of tightening torque to the electrode terminal. This intermediary approach secures the electrical connection through the bus bar-end plate-fastening member assembly while protecting the vulnerable electrode terminal.
4Reliability
If the nut is non-rotatably fixed to the end plate to prevent rotation of the junction bus bar, then unwanted force on the electrode terminal is avoided, but the structure becomes more complex and harder to assemble
Solution Approach 1:
The fastening member is designed to move within the recess rather than being rigidly fixed, simplifying the structure by eliminating the need for anti-rotation mechanisms. The movable design inherently prevents unwanted rotation and force transmission to the electrode terminal while reducing assembly complexity.
Data Source
AI summary
To prevent an increase in the electrical resistance between a terminal for external connection and a cell terminal of a battery cell of a battery cell group. A battery module 100 includes a battery cell group 10, a pair of end plates 20, a bus bar 30, and a fastening member 40. The end plate 20 includes a recess 21 adapted to partially house the fastening member 40 in a mutually movable manner in one direction (X-direction) corresponding to the stacked direction of the plurality of battery cells 1. The battery module 100 also has a gap S between an inner side wall 21a of the recess 21 and the fastening member 40 in the one direction (X-direction).