Battery Pack Bus Bar Laser Welding Thermal Insulation
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Solution Overview
Problem
The electrical insulation property of resin insulating parts in battery packs deteriorates due to heat generated during laser welding of bus bars and external terminals, leading to reduced insulation between cell cases and external terminals.
Innovation Solution
A method for manufacturing battery packs where the welded portion between the bus bar and external terminal is configured to extend in the thickness direction of the external terminal, with a space intervening between the welded portion and the insulating part, preventing heat transfer to the insulating part, and using penetration laser welding to release gases and accommodate foreign substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is performed to join bus bar and external terminal, then welding strength and electrical conductivity are improved, but heat generated during welding deteriorates the electrical insulation property of the insulating part
Solution Approach 1:
The patent introduces a space (intervening region) between the welded portion and the insulating part as a mediator. This space acts as a thermal barrier that prevents heat generated during laser welding from reaching the insulating part, thereby protecting its electrical insulation property while still achieving strong welding between the bus bar and external terminal.
Solution Approach 2:
The patent segments the structure by creating a distinct space between the welded portion and the insulating part. This segmentation separates the high-temperature welding zone from the temperature-sensitive insulating part, allowing the welding process to proceed without compromising the insulation properties.
2Manufacturing precision
If laser beam is irradiated to melt metal for welding, then welding quality is improved, but heat transfer to surrounding parts causes deterioration of insulating properties
Solution Approach 1:
The space between the welded portion and insulating part serves as a thermal mediator that blocks heat transfer. This intermediary region allows high-quality laser welding to be performed while preventing the harmful thermal effects from reaching the insulating part.
Solution Approach 2:
The patent converts the potential harmful effect of heat generation during laser welding into a beneficial outcome by designing a space structure that directs and contains the heat within the welded region, preventing it from reaching the insulating part while ensuring thorough melting and bonding of the metal components.
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 configuration maintains the electrical insulation property of the insulating part, ensuring reliable insulation between cell cases and external terminals, enhances the strength and conductivity of the welded portion, and reduces environmental pollution from spatters.
Implementation Method 1
a laser beam is irradiated onto the front surface of the bus bar, i.e., from above the bus bar, in the thickness direction of the external terminal, thereby melting a part of the bus bar
Implementation Method 2
the external terminal and the bus bar are welded to each other by laser welding
Implementation Method 3
an insulating part made of resin having an electrical insulation property and interposed between a front surface of the cell case and a back surface of the external terminal to electrically insulate the cell case and the external terminal from each other
Data Source
AI summary
In a laser welding step, a laser beam is irradiated fin a thickness direction of an external terminal from a side of a front surface of a bus bar toward a space. This irradiation melts a separated portion of the external terminal, i.e., a portion located apart from the insulating part by the space between the insulating part and the separated portion in the thickness direction, and an opposed portion of the bus bar, i.e., a portion opposed to the space via the separated portion in the thickness direction, thereby forming a welded portion including the separated portion and the opposed portion melted together.