Battery Pack Insulator for Joint Strength
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Solution Overview
Problem
Conventional battery packs face joint breakage issues between bus bars and electrode terminals due to weak laser welding, especially under impact or vibration loads, as there is inadequate constraint in the arrangement direction, leading to excessive displacement and stress on the welding portion.
Innovation Solution
Incorporating an insulator, such as rubber or resin, with an initial thickness greater than the gap between the binding bars and battery cells, which compresses and provides frictional resistance to prevent displacement and maintain contact, thereby enhancing the structural integrity of the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is used to join electrode terminals and bus bar, then the number of steps is reduced compared with screw fastening, but the strength of the joint portion becomes weaker
Solution Approach 1:
The patent introduces a binding bar as an intermediary component between the end plates and battery cells. This binding bar, when elastically deformed during assembly, creates a clamping force that mechanically secures the battery cells, thereby strengthening the overall structural integrity and protecting the laser-welded joints from excessive stress.
Solution Approach 2:
The binding bar is designed with elastic deformation capability that allows it to be compressed during assembly. This pre-compression creates a cushioning effect that absorbs and distributes impact forces before they can reach the welded joints, preventing breakage under impact or vibration loads.
2Stability of the object's composition
If binding bars are used to fasten end plates, then structural stability is improved, but the battery cells may still displace under impact in the arrangement direction
Solution Approach 1:
The patent changes the mechanical parameters of the binding bar by selecting materials with appropriate elastic moduli and designing specific cross-sectional dimensions. This allows the binding bar to exhibit controlled elastic deformation under impact loads, maintaining structural stability while accommodating displacement to protect the welded joints.
Solution Approach 2:
The binding bar may be constructed from composite materials or materials with graded properties that combine high strength for structural stability with sufficient elasticity for impact absorption. This composite approach allows simultaneous achievement of structural stability and impact resistance.
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 insulator effectively reduces the likelihood of joint breakage by maintaining contact between the battery cells and binding bars, even under large external forces, without altering the battery pack's external dimensions, and reduces the peeling force at the welding portion below the allowable value.
Implementation Method 1
friction with an insulator such as rubber or a resin sandwiched between the binding bar and the battery cell can reduce cell displacement in the direction of the external force
Implementation Method 2
an insulator sandwiched in a gap between each of the binding bars and the battery. The insulator has an initial thickness larger than a thickness of the gap before insertion into the gap in a compressed state
Data Source
AI summary
A battery pack includes: a plurality of battery cells arranged in a line in one arrangement direction; a pair of end plates disposed at opposite ends of the plurality of battery cells in the arrangement direction; a pair of binding bars disposed on opposite sides of the plurality of battery cells in a direction perpendicular to the arrangement direction; and an insulator disposed in a gap between each of the binding bars and the battery cells. The insulator having an initial thickness larger than a thickness of the gap before insertion of the insulator into the gap in a compressed state. The end plates sandwich the battery cells therebetween in the arrangement direction, and the binding bars sandwich the battery cells therebetween in the direction perpendicular to the arrangement direction.