Battery Frame Cooling With Integrated Gravity Heat Pipes

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Solution Overview

Problem

Existing cooling devices for electrical energy storage devices face challenges in easily integrating gravitational heat pipes in a space-saving and efficient manner, particularly for high-voltage traction batteries in electric vehicles.

Innovation Solution

The integration of gravitational heat pipes within a frame that forms receptacles for energy storage cells, using a working medium that evaporates to transport waste heat against gravity and condenses on a heat sink, with the frame made of thermally conductive materials like aluminum or magnesium, and incorporating crash structures for protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If gravitational heat pipes are integrated into the frame structure, then space is saved and integration is simplified, but the frame must be made of thermally conductive materials which may increase weight

Engineering Contradiction:
Improvecooling device volumeVSAvoidframe weight
Core Design Contradiction:
Volume of moving objectVSWeight of moving object

Solution Approach 1:

The heat pipes are integrated directly into the frame structure, merging the cooling function with the structural support function. This eliminates the need for separate cooling components and reduces overall space while the frame material provides both structural strength and thermal conduction.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The frame serves multiple functions: it provides structural support for the energy storage cells, acts as a thermal conduction path for waste heat removal, and serves as a mounting structure. By making the frame thermally conductive, it simultaneously performs mechanical and thermal functions.

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

2Temperature

If the frame is made of highly thermally conductive materials like aluminum or magnesium, then heat transfer efficiency is improved, but the structural strength and crash protection may be reduced

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidframe strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The frame is constructed from composite materials or material combinations that provide both high thermal conductivity and sufficient mechanical strength. This may involve using aluminum alloys or magnesium alloys that balance thermal and mechanical properties, or combining different materials in a composite structure.

Inventive Principle:
Principle #40Composite materials

3Device complexity

If gravitational heat pipes are used for cooling, then the cooling system is simplified and reliability is improved, but the heat pipes require vertical orientation which limits design flexibility

Engineering Contradiction:
Improvecooling system complexityVSAvoiddesign flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

By integrating the heat pipes directly into the frame structure, the cooling system becomes part of the overall device architecture rather than a separate add-on. This simplification comes at the cost of requiring the frame to accommodate vertical heat pipe orientation.

Inventive Principle:
Principle #5Merging (Combining)

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 solution allows for efficient and space-saving integration of gravitational heat pipes, effectively cooling energy storage cells while providing protection against forces and ensuring reliable heat management, enhancing the performance and safety of electrical energy storage devices in motor vehicles.

Implementation Method 1

A working fluid is arranged within this sleeve, which remains in a liquid state as long as the temperature of the energy storage cells caused by the waste heat falls below the boiling point of the liquid working fluid. As soon as the temperature exceeds the boiling point, the working fluid evaporates.

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

The working fluid rises as vapor against the direction of gravity, condenses there on a heat sink of the cooling unit coupled to the gravitational heat pipe, and thus releases the transported waste heat to the heat sink.

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 3

Gravitational heat pipes, or two-phase thermosiphons, are heat exchangers that transfer waste heat via the latent heat of vaporization.

Methodology Applied
Scientific EffectLatent heat of vaporization: Latent Heat

Implementation Method 4

The working fluid then changes back from the gaseous state to the liquid state and falls back down as liquid droplets due to gravity. The return transport of the condensed working fluid is therefore carried out by gravity.

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 5

The frame is made of a highly thermally conductive material, such as aluminum or magnesium. The energy storage cells can then transfer the waste heat via their highly thermally conductive walls to the gravity heat pipes

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4315480B1Cooling device for an electrical energy store having gravity-assisted heat pipes, electrical energy store, and motor vehicle
Publication Date: 2025.01.22 BAYERISCHE MOTOREN WERKE AG
  • EP4315480B1 patent drawingFigure 1~2
  • EP4315480B1 patent drawingFigure 3~4
  • EP4315480B1 patent drawingFigure 5~6

AI summary

The invention relates to a cooling device for an electrical energy store (EES) for cooling energy storage cells (6) of the electrical energy store (EES), the cooling device comprising: - gravity-assisted heat pipes (12) having a working medium for absorbing waste heat of the energy storage cells (6); and - a frame (5) having walls (11) for forming receptacles for the energy storage cells (6); wherein the gravity-assisted heat pipes (12) are integrated into the walls (11). The invention also relates to an electrical energy store (EES) and to a motor vehicle.