Battery Pack Lead-Out Layout for Heat and Overcurrent Protection
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Solution Overview
Problem
Existing battery packs for power tools experience safety and reliability issues due to increased heat generation from discharge and charge currents, which can shorten their lifespan and require frequent replacement.
Innovation Solution
A battery pack design featuring non-cylindrical cells with asymmetrical lead-out pieces and a protective element that disconnects the discharge path when current exceeds a preset threshold, along with a cell elastic piece for shock resistance and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If discharge current and charge current are increased to improve power output and operating efficiency, then the power and productivity are improved, but heat generation increases causing safety and reliability issues
Solution Approach 1:
The patent changes the physical parameters of the lead-out pieces by making their lengths unequal, which alters the electrical resistance distribution and current density in the battery pack. This parameter modification helps manage heat generation while maintaining high current capability for improved power output and reliability
Solution Approach 2:
The patent applies local quality by making different lead-out pieces have different lengths based on their specific positions and thermal conditions. The lead-out piece closer to the protective element has greater length to dissipate heat locally, while others have shorter lengths, optimizing heat management at critical locations without compromising overall power output
2Productivity
If discharge current is increased to improve operating efficiency, then productivity is improved, but heat generation increases reducing battery pack lifespan
Solution Approach 1:
By modifying the length parameter of lead-out pieces, the patent optimizes electrical resistance and current distribution to reduce excessive heat generation. This allows the battery pack to maintain high operating efficiency for improved productivity while reducing thermal stress that would otherwise shorten battery pack lifespan
Solution Approach 2:
The patent converts the potentially harmful effect of heat generation into a beneficial design feature by strategically placing longer lead-out pieces in high-heat areas. The increased length of specific lead-out pieces acts as a heat dissipation mechanism, transforming the harmful thermal effect into a benefit that protects battery components and extends lifespan
3Temperature
If lead-out piece lengths are made unequal to enhance heat dissipation, then temperature control is improved, but device complexity increases
Solution Approach 1:
The patent deliberately introduces asymmetry by making lead-out piece lengths unequal rather than uniform. This asymmetric design optimizes heat dissipation by providing longer conduction paths in areas requiring greater thermal management, while maintaining relatively simple overall structure that does not significantly increase device complexity
Solution Approach 2:
The patent applies local quality by differentiating lead-out piece lengths only where thermal conditions require it, specifically making the lead-out piece closer to the protective element longer. This localized modification achieves improved temperature control without unnecessarily complicating the entire battery pack structure
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
Reduces heat generation, enhances safety, and extends the service life of the battery pack by preventing overheating and improving reliability through effective heat dissipation and protective mechanisms.
Implementation Method 1
the heat generation of components of the battery pack through which the currents flow increases gradually. The components include positive and negative terminal poles, circuit boards, and lead-out pieces connecting cells. Especially when a power tool keeps working for a while with a high current, the temperature on the components rises sharply
Implementation Method 2
The positive lead-out piece is connected in series between at least one cell positive electrode and the battery pack positive terminal. The negative lead-out piece is connected in series between at least one cell negative electrode and the battery pack negative terminal
Data Source
AI summary
A battery pack includes a cell assembly. The cell assembly includes a cell assembly positive terminal, a cell assembly negative terminal, a positive lead-out piece, a negative lead-out piece, a discharge path, and a protective element. The positive lead-out piece connects the cell assembly positive terminal to a battery pack positive terminal. The negative lead-out piece connects the cell assembly negative terminal to a battery pack negative terminal. The protective element is disposed on the discharge path. When the discharge current of the discharge path is greater than or equal to a preset current, the protective element turns off. The length of one of the positive lead-out piece or the negative lead-out piece close to the protective element is greater than the length of the other one of the positive lead-out piece or the negative lead-out piece away from the protective element.