Battery Pack Pressure-Driven Safety Switch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary battery packs, especially those with a multi-cell structure, face significant safety risks due to potential fires or explosions from abnormal operations like overcharge, overdischarge, and short circuits, and existing safety systems may fail to protect the battery pack if the battery management system (BMS) is not supplied with electric current.
Innovation Solution
A battery pack design incorporating a pressure-driven switch and a cut-off portion that detects expansion in battery cells or modules, causing an intentional short circuit to interrupt electrical connections, thereby securing safety independently of the BMS, and utilizing the pressure generated from overcharge to protect the pack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery management system (BMS) is used to detect and control abnormal operations, then the reliability of safety monitoring is improved, but the system becomes dependent on external power supply which may fail during abnormal conditions
Solution Approach 1:
The battery pack uses its own internal pressure generation from abnormal operations (overcharge, short circuit, etc.) to automatically activate the safety mechanism. The pressure itself serves as both the indicator of abnormality and the activation force for the cutoff, eliminating dependency on external power supply for safety monitoring.
Solution Approach 2:
The harmful pressure generated by battery swelling or gas accumulation during abnormal operations is converted into a useful signal to trigger the safety cutoff. The same pressure that indicates danger becomes the actuating force for the pressure-driven switch, enabling autonomous safety response.
2Speed
If active safety control systems are implemented to interrupt electrical connection during abnormal operations, then the safety response time is improved, but the system requires continuous power supply which may not be available during failures
Solution Approach 1:
The patent replaces electronic active control systems with a passive mechanical pressure-driven switch. The mechanical force from pressure directly actuates the cutoff mechanism, eliminating the need for continuous power supply while maintaining fast response speed. The mechanical system activates automatically when pressure threshold is reached.
Solution Approach 2:
The pressure-driven switch is pre-configured to automatically activate at a predetermined pressure threshold. No real-time monitoring or decision-making is needed during the abnormal event - the system is already set to respond immediately when the pressure condition is met, enabling fast passive safety response.
3Reliability
If a pressure-driven switch is added to enable passive safety response, then the autonomy of safety protection is improved, but the device structure becomes more complex
Solution Approach 1:
The pressure-driven switch and cutoff portion are integrated directly into the existing battery pack structure. The safety mechanism shares space and structural elements with the battery assembly, minimizing additional components. The cutoff portion is positioned to naturally interrupt electrical connections without requiring separate complex mounting structures.
Solution Approach 2:
The pressure-driven switch acts as a simple intermediary between the pressure condition and the cutoff action. It translates pressure force directly into mechanical movement to open the circuit, without requiring complex electronics, sensors, or control logic. This simple mediation adds minimal structural complexity while achieving autonomous safety response.
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 enhances safety by allowing the battery pack to self-protect even when the BMS is not operational, reducing the risk of damage by isolating the affected cells and enabling flexible design with minimal structural changes, while ensuring reliable operation across various load conditions.
Implementation Method 1
a pressure driven switch connected to or adjacent to the battery cells or battery modules at which the cut-off portion is located
Data Source
Figure 1
Figure 2
AI summary
Disclosed herein is a battery pack including a power supply unit including two or more battery cells or battery modules electrically connected to each other, a cut-off portion located at at least one series connection region between the battery cells or the battery modules to interrupt electrical connection in the battery pack upon occurrence of a short circuit of the battery cells or the battery modules guided by a pressure driven switch, the pressure driven switch connected in parallel to the battery cells or the battery modules at which the cut-off portion is located to detect expansion in volume of the battery cells or the battery modules when the power supply unit malfunctions and to guide occurrence of a short circuit of the battery cells or the battery modules, and external input and output terminals connected to electrode terminals located at outermost sides of the power supply unit to supply power to an external device.