Battery Pack Waterproof Bag with Check Valve for Thermal Management

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Solution Overview

Problem

Conventional battery packs face increased weight and reduced thermal conductivity due to the need for a large volume of potting resin to fill the space between battery cells and the battery case, which compromises heat radiation and waterproofing.

Innovation Solution

A battery pack design featuring a waterproof bag with a check valve that allows air to escape, ensuring the potting resin contacts the battery cells tightly, minimizing volume while maintaining waterproofing and enhancing thermal conductivity, and includes a manufacturing method to inject the resin efficiently, even in complex shapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the space between battery cell and battery case is filled with potting resin to thermally couple them, then heat radiation is improved, but the volume of potting resin increases and weight increases

Engineering Contradiction:
Improveheat radiationVSAvoidweight of battery pack
Core Design Contradiction:
TemperatureVSWeight of stationary object

Solution Approach 1:

The invention extracts the air from the waterproof bag by using a check valve to exhaust the inner air, creating a vacuum environment. This allows the potting resin to tightly contact the battery cells without needing to fill the entire space between the battery cells and the battery case, thereby reducing the volume and weight of the potting resin while maintaining effective thermal coupling.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the pressure parameter inside the waterproof bag by exhausting the air to create a negative pressure environment. This parameter change enables the potting resin to be drawn into tight contact with the battery cells through pressure differential, achieving effective thermal coupling with minimal resin volume.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If the space between battery cell and battery case is filled with potting resin to thermally couple them, then heat radiation is improved, but the volume of injected potting resin increases

Engineering Contradiction:
Improveheat radiationVSAvoidvolume of potting resin
Core Design Contradiction:
TemperatureVSVolume of stationary object

Solution Approach 1:

The invention extracts the air from the waterproof bag by using a check valve to exhaust the inner air, creating a vacuum environment. This allows the potting resin to tightly contact the battery cells without needing to fill the entire space between the battery cells and the battery case, thereby reducing the volume and weight of the potting resin while maintaining effective thermal coupling.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the pressure parameter inside the waterproof bag by exhausting the air to create a negative pressure environment. This parameter change enables the potting resin to be drawn into tight contact with the battery cells through pressure differential, achieving effective thermal coupling with minimal resin volume.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If check valve is provided to exhaust inner air for tight contact, then thermal conductivity is improved, but device complexity increases

Engineering Contradiction:
Improvethermal conductivityVSAvoidcomplexity of waterproof bag structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The check valve is designed to automatically exhaust the inner air from the waterproof bag without requiring external control mechanisms. The valve opens automatically when air needs to be exhausted and closes automatically to maintain the vacuum environment, enabling the system to self-regulate the internal pressure and achieve tight contact between the potting resin and battery cells.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The check valve acts as an intermediary component that mediates between the internal vacuum environment and the external atmosphere. It allows controlled air exhaust while maintaining the vacuum seal, enabling the tight contact of potting resin without requiring complex active control systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 allows for efficient heat radiation from battery cells with minimal potting resin volume, improved thermal conductivity, and effective waterproofing, preventing thermal runaway and adverse effects on circuit boards.

Implementation Method 1

a waterproof bag having a check valve which opens only at the time of exhausting an inner air... by introducing the uncured pasty or liquid potting resin into the waterproof bag... the air inside the waterproof bag is exhausted through the check valve, and equally the potting resin tightly contacts the surfaces of the battery cells

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP2999026B1Battery pack manufacturing method
Publication Date: 2018.01.17 SANYO ELECTRIC CO LTD
  • EP2999026B1 patent drawingFigure 1~2
  • EP2999026B1 patent drawingFigure 3~4
  • EP2999026B1 patent drawingFigure 5

AI summary

A battery pack comprises battery cells, a battery holder holding the battery cells, a waterproof bag storing the battery holder holding the battery cells as a waterproof structure, and a potting resin being injected in the waterproof bag, and the waterproof bag has a check valve which opens only at the time of exhausting an inner air. In a state that the potting resin is injected in the waterproof bag, the air inside the waterproof bag is exhausted through the check valve, and equally the potting resin tightly contacts the surfaces of the battery cells and the battery holder.