Battery Pack Cell Layout for Balanced Heat Dissipation

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Solution Overview

Problem

Battery packs experience thermal stress and premature safety shutdowns due to internal temperature increases during heavy electrical loads, despite having sufficient battery capacity, as heat generated by internal cells is not effectively dissipated.

Innovation Solution

A thermally balanced battery pack design where individual cells with flat sides contact the heat-conducting side walls, with outer cells acting as heat sinks to dissipate heat generated by inner cells, and volume compensation elements made of heat-conducting material are used to maintain efficient heat dissipation, ensuring that both side walls contribute to heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If several individual cells are arranged closely together in the housing to provide a compact battery pack, then the battery pack achieves high power density and compact size, but the internal temperature of the battery pack rises significantly under electrical load

Engineering Contradiction:
Improvebattery pack sizeVSAvoidinternal temperature
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The battery pack is segmented into outer individual cells and inner individual cells, with the outer cells serving as thermal management elements. This segmentation allows the outer cells to act as heat sinks that actively cool the inner cells through thermal contact, resolving the temperature rise issue while maintaining compact size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inner individual cells are nested within the structure formed by outer individual cells, creating a nested configuration where inner cells are surrounded by outer cells that provide thermal management. This nesting arrangement enables efficient heat dissipation from internal cells to outer cells and subsequently to the housing.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Quantity of substance

If the receiving space is tightly filled with individual cells to maximize energy density, then the battery pack achieves high capacity, but heat dissipation from internal cells becomes insufficient

Engineering Contradiction:
Improvebattery capacityVSAvoidheat dissipation efficiency
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The outer individual cells are given a dual function: they serve as energy storage units and simultaneously as heat sinks for thermal management. This local quality differentiation allows specific cells (outer ones) to be optimized for heat dissipation while inner cells focus on energy storage, resolving the conflict between capacity and heat dissipation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The outer individual cells perform multiple functions: they store electrical energy like all battery cells, but additionally serve as thermal management components by acting as heat sinks. This multi-functionality allows the same component to address both energy density and heat dissipation requirements simultaneously.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Power

If inner individual cells are surrounded by outer individual cells for compact arrangement, then the battery pack achieves high power density, but inner cells experience thermal overload and premature safety shutdown

Engineering Contradiction:
Improvepower densityVSAvoidoperational reliability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The outer individual cells act as intermediary thermal management elements between the inner individual cells and the housing. They mediate the heat transfer process by receiving heat from inner cells through thermal contact and conducting it to the housing, preventing direct thermal overload of inner cells and improving operational reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The outer individual cells are positioned beforehand to surround and protect inner cells from thermal stress. This pre-arranged thermal protection structure cushions inner cells against temperature rises before they can experience thermal overload, preventing premature safety shutdown and improving reliability.

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

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

This design prevents thermal overloading of internal cells, maintains a balanced temperature distribution, and ensures efficient heat dissipation, thereby extending the operational life of the battery pack.

Implementation Method 1

At least the side walls of the housing are made of a heat-conducting material

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The waste heat from an inner individual cell that lies flat against the outer individual cell is dissipated to the housing via the outer individual cell, which forms a heat sink

Methodology Applied
Scientific EffectHeat sink: Heat Sink

Implementation Method 3

Cooling fins of the housing are formed on the outer surfaces of the side walls facing away from the receiving space

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4372868A1Battery pack as energy source for electrical consumers
Publication Date: 2024.05.22 ANDREAS STIHL AG & CO KG
  • EP4372868A1 patent drawingFigure 1
  • EP4372868A1 patent drawingFigure 2
  • EP4372868A1 patent drawingFigure 3

AI summary

The invention relates to a battery pack as an energy source for an electrical device, wherein the battery pack (1) has a closed housing (2) with an internal receiving space (3) for several individual cells (4). The housing (2) of the battery pack (1) has a general basic shape with first and second side walls (5, 6), wherein the side walls (5, 6) of the housing (2) are made of a thermally conductive material, and the inner surfaces (7, 8) of the side walls (5, 6) define the receiving space (3). In order to create a thermally balanced battery pack, a cell array (19) consisting of several individual cells (4) is accommodated in the receiving space (3), wherein an individual cell (4) has flat sides (10) and edge sides (11). The individual cells (4) are stacked side by side with their flat sides (10) such that outer individual cells (4a) and inner individual cells (4b) are present.D the outer individual cells (4a) lie with their flat sides (10) in a flat and heat-transferring manner against the inner surfaces (7) of the first side walls (5) of the housing (2), and the inner individual cells (4b) are connected to the outer individual cells (4a) of the cell assembly (19) in a heat-transferring manner.