Bimetal Current Breaker for Reusable Battery Pack Isolation
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Solution Overview
Problem
Conventional current breaking structures in battery packs are not reusable after an abnormal state is resolved, requiring disassembly and replacement of the cut metal member, which affects the reusability of recovered battery cells.
Innovation Solution
A battery pack with a current breaking device using bimetal that can quickly separate and reconnect battery cells based on thermal deformation, allowing for reusability without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional current breaking structure (cut metal member) is used to separate battery cells during abnormal states, then the battery cell can be mechanically separated from the bus bar, but the structure cannot be reused and requires disassembly and replacement
Solution Approach 1:
The patent applies parameter changes by utilizing the thermal expansion coefficient difference between bimetal layers. The bimetallic strip changes its curvature parameter in response to temperature changes, enabling it to automatically open the circuit during overheating and automatically reset when temperature returns to normal, providing reusable current breaking functionality without disassembly.
Solution Approach 2:
The bimetallic current breaking device is self-service in that it automatically responds to temperature changes without external control. When the battery cell overheats, the bimetal automatically bends to break the circuit. When the temperature returns to normal, it automatically returns to its original shape and restores the circuit, eliminating the need for manual intervention or replacement.
2Reliability
If a cut metal member is used for current breaking, then the abnormal battery cell can be separated, but the battery pack requires opening and replacement of the cut member, affecting productivity
Solution Approach 1:
The patent employs dynamics by using a flexible member instead of a rigid cut metal member. The flexible member can dynamically adjust its state between connected and disconnected based on temperature conditions. This dynamic capability allows the system to quickly respond to abnormal states and equally quickly restore normal operation, significantly improving productivity during battery pack restoration.
Solution Approach 2:
The bimetallic strip undergoes phase transitions in response to temperature changes. When heated beyond a certain temperature threshold, the bimetal transitions from a flat state to a bent state, breaking the circuit. When cooled below the threshold, it transitions back to the flat state, restoring the circuit. This phase transition mechanism enables rapid restoration without manual intervention.
3Reliability
If a rigid current breaking structure is used, then the circuit can be broken during abnormal states, but the structure cannot automatically restore connection when the abnormal state is resolved
Solution Approach 1:
The patent utilizes parameter changes through the bimetallic strip's response to temperature variations. The strip's curvature parameter changes automatically with temperature, enabling it to break the circuit when hot and automatically restore the circuit when cool, providing ease of operation through automatic restoration without requiring manual resetting or replacement.
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 bimetal-based current breaking device enables quick separation and reconnection of battery cells during abnormal states, ensuring stable operation and reusability of the battery pack.
Implementation Method 1
a current breaking device using bimetal and having a portion made of bimetal... as heat having a predetermined value or more is transferred from the cylindrical battery cell, the bimetal portion may be bent to space the free end apart from the cylindrical battery cell
Implementation Method 2
the connection between the free end and the cylindrical battery cell may be restored by dissipating the heat transferred to the bimetal portion
Data Source
AI summary
The present disclosure relates to a battery pack and an operation method thereof. The battery pack includes a pack case, a plurality of cylindrical battery cells in the pack case, and a current breaking device in the pack case to connect the plurality of cylindrical battery cells and having a portion including a bimetal. The current breaking device includes a fixed end contacting an electrode terminal of the cylindrical battery cell, a free end contacting an electrode terminal of the surrounding cylindrical battery cell, and a flexible member configured to elastically press the free end toward the surrounding cylindrical battery cell. The battery pack may include a current breaking device using bimetal that is capable of quickly restoring a connection with a surrounding cylindrical battery cell when a state of a battery cell separated from the surroundings in case of an abnormal state thereof is recovered.