EV Battery Module Fastening with Flexible Members to Control Swelling

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Solution Overview

Problem

The uncontrollable swelling of battery cells in electric vehicle batteries affects the reliability by altering cell size and position, causing uneven clearances and thermal uniformity issues, which complicates housing design and increases the risk of damage or rocking within the module.

Innovation Solution

A power supply unit for electric vehicles featuring a tray with a housing and side plates, where flexible members and support bars secure the battery pack, preventing size and position changes during swelling, ensuring thermal uniformity and reliable connection between cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the clearance between cells is reduced to prevent movement during swelling, then the cells are secured in position, but the housing may be damaged or the cells difficult to dispose into the housing

Engineering Contradiction:
Improvecell position stabilityVSAvoidhousing assembly difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-installing buffer members between the cells and the housing before the cells are fully disposed into the housing. This preliminary placement of buffer members ensures that when cells swell, they are constrained by the buffer members rather than damaging the housing or requiring difficult assembly procedures. The buffer members are positioned in advance to anticipate and accommodate cell swelling.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by introducing buffer members that absorb and accommodate the swelling of battery cells during operation. These buffer members are positioned between the cells and the housing structure, providing a cushioning effect that prevents direct contact between swollen cells and the housing, thereby avoiding housing damage while maintaining cell stability.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If the clearance between cells is increased to facilitate assembly, then the cells can be easily disposed into the housing, but the cells may rock in the module during operation

Engineering Contradiction:
Improvehousing assembly easeVSAvoidcell stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-installing buffer members and positioning structures before cells are disposed into the housing. These pre-positioned elements guide the cells into proper positions and prevent excessive movement or rocking, while still allowing sufficient clearance for easy assembly. The buffer members are strategically placed to provide both assembly facilitation and operational stability.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the housing strength is increased to accommodate swollen cells, then the cells are securely contained, but the space occupied by the housing increases

Engineering Contradiction:
Improvecell containment capabilityVSAvoidhousing volume
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent implements beforehand cushioning by introducing buffer members that absorb the volume expansion caused by cell swelling. Instead of increasing housing strength and volume to accommodate swollen cells, the buffer members are positioned between the cells and housing walls to absorb the swelling, allowing the housing to maintain its original dimensions while securely containing the cells during operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

4Reliability

If the clearance between cells is made uniform, then the thermal uniformity of the battery is improved, but the design becomes more complex due to non-uniform swelling

Engineering Contradiction:
Improvethermal uniformityVSAvoidclearance design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by positioning buffer members at specific locations between cells and the housing, rather than attempting to create uniform clearance throughout. The buffer members are strategically placed where cells are most likely to swell and contact the housing, providing localized compensation that maintains thermal uniformity without requiring complex overall design modifications. This approach addresses non-uniform swelling through targeted local adjustments.

Inventive Principle:
Principle #3Local quality

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 solution effectively secures the battery pack, maintaining thermal uniformity and reliability by preventing cell movement and deformation, thus enhancing the overall performance and stability of the power supply unit.

Implementation Method 1

first flexible members disposed between the first side plate and the battery pack, and between the third side plate battery pack respectively, for fastening the battery pack

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

at least one battery module fixed on the tray via a strip

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2735041B1Power supply unit for electric vehicle
Publication Date: 2021.02.24 BYD CO LTD
  • EP2735041B1 patent drawingFigure 1~2
  • EP2735041B1 patent drawingFigure 3

AI summary

A power supply unit for an electric vehicle comprises a tray (16) and at least one battery module (200) fixed on the tray (16) via a strip (2). Each battery module (200) comprises: a housing having a bottom plate mounted onto the tray (16) and first to fourth side plates disposed on the bottom plate, wherein the first and third side plates are opposed to each other in a thickness direction and the second and fourth side plates are opposed to each other in a front-rear direction; a battery pack, disposed in the housing, having a plurality of cells arranged along the thickness direction; and flexible members disposed between the first and third side plates and the battery pack respectively, for fastening the battery pack.