Battery Pack Isolating Wall Design for Moisture Protection
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Solution Overview
Problem
Battery packs for hand-held electric power tools are vulnerable to corrosion from moisture due to the need for ventilation to dissipate heat, which risks moisture penetration through openings in the housing, potentially leading to failure of battery cells and circuit boards.
Innovation Solution
The battery pack design incorporates both open and isolated spaces within the housing, with moisture-prone components in the isolated space and less vulnerable components in the open space, using flexible and elastic materials for isolating walls to minimize gaps and prevent moisture ingress, while allowing for ventilation to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the housing is completely or hermetically sealed to prevent moisture penetration, then moisture protection is improved, but heat dissipation deteriorates causing battery cell overheating
Solution Approach 1:
The housing internal space is segmented into a first space and a second space separated by a partition wall. The first space allows air passage for heat dissipation, while the second space is isolated from external air to protect moisture-sensitive components. This spatial segmentation resolves the contradiction by providing both ventilation pathways and protected zones within the same housing structure.
Solution Approach 2:
Different regions of the housing are assigned different sealing characteristics. The partition wall creates a locally sealed environment in the second space for components requiring moisture protection, while the first space remains open for thermal management. This local differentiation of sealing quality allows simultaneous achievement of heat dissipation and moisture protection.
2Temperature
If openings are formed in the housing for ventilation and contact terminal insertion, then heat dissipation and electrical connection are improved, but moisture penetration risk increases
Solution Approach 1:
The housing space is divided into sealed and unsealed zones. Components requiring moisture protection (battery cells, circuit board) are placed in the sealed second space, while contact terminals that must interface with external tools are positioned in the unsealed first space. This segmentation allows openings for ventilation and electrical connection without exposing moisture-sensitive components.
Solution Approach 2:
The partition wall acts as an intermediary barrier between the sealed second space and the unsealed first space. It allows the system to maintain isolated protected zones while still providing necessary openings in the housing for heat dissipation and electrical connections in the non-protected first space.
3Manufacturing precision
If flexible and elastic materials are used for isolating walls to minimize gaps, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The partition wall is constructed using flexible and elastic materials that can deform to accommodate manufacturing tolerances and assembly variations. This flexibility automatically minimizes gaps between the partition wall and surrounding housing components without requiring complex precision machining or additional sealing mechanisms, thus reducing overall device complexity while improving sealing effectiveness.
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 effectively reduces the risk of corrosion and failure by isolating vulnerable components from moisture while maintaining ventilation for heat dissipation, thereby extending the lifespan and reliability of the battery pack.
Implementation Method 1
portions of the isolating wall that contact the battery cells are formed from a material that is more flexible than that of the housing
Implementation Method 2
it has been necessary to define at least one opening in the housing and to passively (naturally) or forcibly ventilate the space inside the housing through the at least one opening
Data Source
AI summary
A battery pack (10; 110) for a power tool includes a housing (18) made of a rigid material. The housing contains a cooling air passage (54), which is in gaseous communication with the outside environment, and at least one isolated space (52). At least one isolating wall (44) is disposed inside the housing so as to physically separate and isolate the cooling air passage from the at least one isolated space. A plurality of battery cells (32) is disposed within the housing such that an end portion (32a) thereof is disposed within the at least one isolated space and an intermediate portion (32b) thereof is disposed adjacent the cooling air passage. First portions (78) of the at least one isolating wall respectively contact the plurality of battery cells and are comprised of a material that is more flexible and/or elastic than the rigid material of the housing (18).