Lithium Battery Bushing for Heavy Current and Leaktightness
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Solution Overview
Problem
Existing bushings in lithium-ion storage batteries are not suitable for passing very heavy currents, typically more than 100 A, due to issues such as loss of contact from thermal expansions and lack of suitable geometries, and they fail to maintain perfect leaktightness throughout the battery's working life.
Innovation Solution
A bushing design featuring two electrically insulating washers and two electrically conductive pieces with a tight fitting mechanism that allows axial compression and radial tightening, ensuring perfect leaktightness and mechanical holding, along with materials and cross-sections adapted to allow heavy currents to flow, and a continuous weld bead for enhanced mechanical cohesion and leaktightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional bushing design is used, then the structure is simple and easy to manufacture, but it cannot pass heavy currents more than 100 A due to thermal expansion causing loss of contact
Solution Approach 1:
The bushing is divided into multiple functional segments: a first conductive piece for electrical connection, insulating washers for electrical isolation and mechanical support, and a second conductive piece for external connection. This segmentation allows each component to be optimized for its specific function, enabling heavy current passage while maintaining structural integrity against thermal expansion.
Solution Approach 2:
The bushing components are nested within each other: the first conductive piece is inserted through the wall, surrounded by insulating washers, which are in turn surrounded by the second conductive piece. This nested arrangement compactly integrates electrical conduction, insulation, and mechanical retention functions in a space-efficient manner.
2Reliability
If a rigid metal housing is used, then leaktightness below 10−8 mbar·l/s is achieved, but the bushing fails to maintain leaktightness throughout battery life due to thermal expansions
Solution Approach 1:
The bushing design incorporates materials and geometries that adapt to thermal parameter changes during battery operation. The conductive pieces and insulating washers are dimensioned and material-selected to maintain compressive contact pressure across the sealing interface despite thermal expansion and contraction cycles, ensuring leaktightness is maintained throughout the battery's working life.
Solution Approach 2:
The bushing structure includes pre-compression elements and compliant materials that anticipate thermal expansions during battery operation. The design inherently compensates for thermal effects before they compromise the seal, maintaining leaktightness without requiring active adjustment mechanisms.
3Reliability
If the bushing components are tightly fitted, then mechanical holding and leaktightness are improved, but the assembly complexity increases
Solution Approach 1:
The bushing is segmented into pre-fabricated components (first conductive piece, insulating washers, second conductive piece) that can be manufactured and quality-tested separately, then assembled in a standardized sequence. This segmentation simplifies the assembly process while ensuring tight fitting and mechanical holding through precise component interfaces.
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 bushing design enables the flow of heavy currents up to 500 A with minimal temperature rise and maintains leaktightness throughout the battery's life, ensuring reliable operation and mechanical integrity.
Implementation Method 1
two electrically conductive pieces, of which a male piece is fitted tightly in the female piece, each of the conductive pieces having a bearing portion bearing with its surface under pressure against a bearing portion of the washers
Implementation Method 2
each of the conductive pieces having a bearing portion bearing with its surface under pressure against a bearing portion of the washers, the female piece furthermore bearing with its surface under pressure against the guiding portions of the washers
Implementation Method 3
a continuous weld bead for enhanced mechanical cohesion and leaktightness
Data Source
AI summary
The present invention relates to a bushing forming a terminal for a storage battery, made through an opening connecting to either side of a wall comprising two opposing surfaces, which comprises: two electrically insulating washers, each comprising a bearing portion resting by the surface thereof under pressure against one of the surfaces of the wall and a guiding portion projecting from the bearing portion and resting under pressure against the edge of the opening; two electrically conductive parts, in which a male part is adjusted clamped inside the female part, each one of the parts comprising a bearing portion resting by the surface thereof under pressure against a bearing portion of the washers, the female part resting by the surface thereof under pressure against the guiding portions of the washers. The material(s) of the parts is/are fitted, and the section(s) thereof is/are sized so as to enable the flow of an electric current with a value of no less than 100 A.