Battery Pack Buffer Structure for Underfloor Cell Load Protection
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Solution Overview
Problem
Existing power storage devices mounted under vehicle floors face issues with loads being input to the upper surfaces of cells from the vehicle cabin, leading to potential deformation and increased risk of short circuits.
Innovation Solution
A power storage device design featuring a buffer portion with restraint members and plate members that cover the end edges of cells, along with a pack structure that includes a rigid upper plate portion and a lower plate portion, to distribute and reduce loads on the cell upper surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power storage device is disposed below the floor panel to achieve higher energy density, then the energy density is improved, but load from the vehicle cabin is input to the upper surface of the cell causing potential deformation and short circuit risk
Solution Approach 1:
The patent introduces a buffer portion as an intermediary element positioned between the upper plate portion and the cell. This buffer portion absorbs and distributes the load from the vehicle cabin, preventing direct transmission of force to the cell upper surface. The buffer portion acts as a mediator that protects the cell from harmful loads while maintaining the compact under-floor configuration for high energy density.
Solution Approach 2:
The buffer portion is designed to provide beforehand cushioning to the cell upper surface. By positioning the buffer portion in advance between the upper plate and the cell, the system prepares a protective layer that will absorb potential loads from the vehicle cabin before they can reach the cell, thereby preventing deformation and short circuit risks.
2Use of energy by moving object
If the power storage device is disposed below the floor panel, then the energy density is improved, but the cell is exposed to load from the upper side
Solution Approach 1:
The buffer portion serves as a mechanical intermediary that intercepts and distributes the load from the upper plate portion. Instead of the load being directly applied to the cell upper surface, the buffer portion absorbs and disperses this force, reducing the peak stress on the cell while maintaining the under-floor configuration for high energy density.
Solution Approach 2:
The buffer portion is specifically positioned at the location where load protection is most needed - directly above the cell upper surface. This localized protection approach applies the buffer portion only where the load from the vehicle cabin would directly impact the cell, rather than providing uniform protection throughout the entire structure.
3Reliability
If a buffer portion is added to protect the cell from load, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The buffer portion is designed to serve multiple functions simultaneously: it protects the cell from load, maintains the structural integrity of the pack, and works in conjunction with the upper plate portion and restraint members. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall device complexity while achieving reliable cell protection.
4Strength
If the buffer portion is made of rigid material to resist load, then the load resistance is improved, but the rigidity of the upper plate portion is reduced
Solution Approach 1:
The buffer portion is made of a material with intermediate rigidity - not as rigid as metal but more rigid than soft foam. This composite material approach allows the buffer portion to resist and distribute load effectively while maintaining flexibility to avoid creating stress concentration points that could lead to cell deformation or short circuits. The intermediate rigidity balances load resistance with protection against deformation.
Data Source
AI summary
A plurality of cells are arranged in a first direction, the first direction being a direction along a horizontal direction. Each of the plurality of cells includes an electrode assembly and a cell case that houses the electrode assembly. The cell case includes an upper surface portion facing upward. The upper surface portion includes a first end edge and a second end edge. The first end edge is an end edge on one side in the first direction. The second end edge is an end edge on the other side in the first direction. The first end edge and the second end edge extend along a second direction, the second direction being a direction along the horizontal direction and orthogonal to the first direction. A buffer portion covers the first end edge and the second end edge in each of the plurality of cells.