Power Tool Battery Pack Breathing Structure Against Housing Deformation
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Solution Overview
Problem
Battery packs for power tools face deformation issues due to increased air pressure from temperature changes, which affects the appearance and functionality of the product, as existing sealing methods do not effectively manage air pressure within the sealed chamber.
Innovation Solution
Incorporating elastic pads between cell units and an air-permeable element that connects with the outside air, forming air cavities and allowing pressure balance, while maintaining waterproof and dustproof functionality through a sealing member and air-permeable material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cell units are stacked and sealed with sealant to achieve dustproof and waterproof requirements, then sealing performance is improved, but air pressure increases during temperature changes causing cell deformation and housing deformation
Solution Approach 1:
The patent introduces an air-permeable element (breathable membrane) that allows air molecules to pass through while blocking water and dust. This porous material enables pressure equalization between the sealed chamber and external environment, preventing housing deformation caused by pressure differential, while maintaining the required dustproof and waterproof sealing performance.
Solution Approach 2:
The air-permeable element acts as an intermediary component between the sealed chamber and the external environment. It mediates the pressure differential by allowing controlled air passage while maintaining the sealing barrier against water and dust, thus resolving the contradiction between sealing performance and pressure management.
2Reliability
If the sealed chamber is completely sealed to maintain waterproof performance, then water resistance is improved, but internal air pressure increases causing cell units to move and deform
Solution Approach 1:
The air-permeable element provides a selective barrier that is permeable to air molecules but impermeable to water and dust particles. This allows the sealed chamber to maintain waterproof performance while enabling pressure equalization through air passage, thereby preventing cell unit displacement and deformation caused by pressure differential.
Solution Approach 2:
The sealing system employs different material properties in different locations: the sealant provides complete sealing at critical interfaces, while the air-permeable element provides selective permeability in specific areas where pressure equalization is needed. This local differentiation of sealing quality resolves the contradiction between waterproof performance and pressure management.
3Reliability
If thick sealant is used to ensure sealing performance, then waterproof performance is improved, but the housing deformation under pressure increases due to reduced flexibility
Solution Approach 1:
The air-permeable element serves as a pressure-regulating intermediary that equalizes pressure between the sealed chamber and external environment. This eliminates the pressure differential that would otherwise require thick, rigid sealant, allowing the use of thinner, more flexible sealing materials while maintaining adequate sealing performance.
Solution Approach 2:
The air-permeable element provides beforehand cushioning by preventing pressure buildup in the sealed chamber. By allowing continuous pressure equalization, it prevents the conditions that would lead to housing deformation, thereby protecting the structural integrity without requiring excessive sealing material thickness.
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 balances internal and external air pressure, preventing deformation of the housing and enhancing the safety and performance stability of the battery pack, thereby extending its service life and maintaining its appearance.
Implementation Method 1
an air-permeable element partially disposed on the side surface of the cell assembly and extending into multiple air cavities... the air-permeable element connects with the air outside the sealed chamber
Implementation Method 2
elastic pads separately disposed between adjacent ones of the multiple cell units... air cavities are formed between the elastic pads and the adjacent ones of the multiple cell units
Data Source
AI summary
A battery pack includes a housing; a cell assembly including multiple stacked cell units; elastic pads separately disposed between adjacent ones of the multiple cell units, where air cavities are formed between the elastic pads and the adjacent ones of the multiple cell units; a sealing member disposed at least on the surface of the cell assembly, where the sealing member and the housing form a sealed chamber; and an air-permeable element partially disposed on the side surface of the cell assembly and extending into multiple air cavities along the first direction, where the air-permeable element connects with the air outside the sealed chamber.