Battery Pack Compression via Orthogonal Wedge Mechanism
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Solution Overview
Problem
Conventional battery packs face increased dimensions and weight due to overlapping compression in the battery module and pack states, leading to decreased energy density per unit volume, and wasted space when multiple modules are housed in a battery case.
Innovation Solution
A battery pack design featuring a cell stack with a wedge member and bolt system that applies compression orthogonally to the stacking direction, using inclined abutment faces and a die-cast metal battery case with integrated female threads, allowing for efficient compression of rectangular cells without additional module compression, thus enhancing energy density and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If compression is applied in the battery module state and then again in the battery pack state, then the cells are well-compressed, but the dimensions and weight of the battery pack increase
Solution Approach 1:
The invention extracts the compression function from the battery module level and applies it directly at the battery pack level. By removing the intermediate compression structure (ladder frames and end plates) and applying compression directly to the cell stack using a wedge member and bolt, the patent eliminates redundant structural components while maintaining effective compression, thereby reducing overall weight.
Solution Approach 2:
The invention merges the compression function with the battery pack structure itself. The compression means (wedge member and bolt) are integrated into the battery pack assembly, combining the functions of structural support and compression application in a single integrated system, eliminating the need for separate compression structures at the module level.
2Quantity of substance
If multiple battery modules are housed in the battery case, then the battery capacity increases, but wasted space occurs and energy density per unit volume decreases
Solution Approach 1:
The invention merges multiple cells into a single cell stack configuration, eliminating the need for separate battery modules. By stacking cells directly and applying compression at the pack level, the patent achieves better space utilization and removes wasted space between modules, thereby increasing energy density while maintaining or enhancing battery capacity.
3Strength
If a conventional compression structure with ladder frames and end plates is used, then the cells are compressed, but the structural complexity and weight increase
Solution Approach 1:
The invention extracts the essential compression function from the complex ladder frame and end plate structure. By removing these intermediate structural elements and applying compression directly to the cell stack using a simple wedge member and bolt mechanism, the patent maintains effective compression capability while dramatically reducing structural complexity.
Solution Approach 2:
The invention changes the compression application method from distributed compression through ladder frames to concentrated compression through a wedge member. This parameter change in the compression mechanism simplifies the structure while maintaining or improving compression effectiveness.
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 design effectively suppresses cell expansion with strong, simple compression, enhances energy density per unit volume, and reduces the battery pack's dimensions and weight by applying compression only once to the cell stacks, while preventing wedge member tilting and ensuring structural integrity.
Implementation Method 1
a wedge member disposed on the side of the end plate opposite to the cell stack, and a bolt disposed in a bolt screw-in direction that is orthogonal to the stacking direction and urging the wedge member toward a bottom wall of the battery case
Implementation Method 2
first abutment faces via which the wedge member and the end plate abut against each other being formed from an inclined face that is inclined toward the bolt side in the bolt screw-in direction
Data Source
AI summary
A battery pack (11) in which a cell stack (15) having a plurality of rectangular cells (14) stacked is housed in an interior of a battery case (12) includes an end plate (20) disposed on one end side in a stacking direction of the cell stack (15), a wedge member (19) disposed on the side of the end plate (20) opposite to the cell stack (15), and a bolt (18) disposed in a bolt screw-in direction that is orthogonal to the stacking direction and urging the wedge member (19) toward a bottom wall (12c) of the battery case (12), and first abutment faces (19b, 20a) via which the wedge member (19) and the end plate (20) abut against each other are formed from an inclined face that is inclined toward the bolt (18) side in the bolt screw-in direction. Therefore, it is possible to apply strong compression to the cell stack (15) with a simple structure and to suppress expansion of the rectangular cell (14), and moreover to enhance the energy density per unit volume while reducing the dimensions and weight of the battery pack (11).