Flexible Busbar Module Branch Strip Segmentation for Battery Assembly

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Solution Overview

Problem

Conventional busbar modules face difficulties in ease of attachment and deformation accommodation due to increased stiffness from numerous voltage detection wires, making it hard to absorb thermal expansion and manufacturing dispersion in battery assemblies.

Innovation Solution

A busbar module with a flexible circuit board featuring a band-shaped main strip and branch strips that can bend and stretch, incorporating a thin-layer portion with reduced conductor layers to enhance flexibility, allowing the module to adapt to battery assembly expansions and contractions without deforming the main strip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the number of battery cells is increased to increase capacity, then the battery assembly capacity increases, but the number of voltage detection lines increases, making the busbar module stiffer and harder to attach

Engineering Contradiction:
Improvebattery assembly capacityVSAvoidease of attachment
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The circuit board is segmented into a main strip and multiple branch strips, where each branch strip independently connects to a busbar. This segmentation allows each branch strip to flex independently, maintaining ease of attachment even when the number of battery cells and voltage detection lines increases.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different structural qualities to different parts of the circuit board. The main strip has a standard thickness for structural stability, while the branch strips have a thinner portion that provides enhanced flexibility. This local differentiation allows the system to maintain both structural integrity and ease of attachment.

Inventive Principle:
Principle #3Local quality

2Reliability

If the number of voltage detection lines is increased to monitor more battery cells, then the monitoring coverage increases, but the stiffness of the busbar module increases, reducing its ability to absorb deformation

Engineering Contradiction:
Improvevoltage detection coverageVSAvoiddeformation absorption capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The circuit board is divided into a main strip and multiple independent branch strips. Each branch strip can deform independently to accommodate battery cell expansion and contraction, allowing the system to maintain high voltage detection coverage while preserving deformation absorption capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The branch strips incorporate thin portions with reduced protective layer thickness, creating flexible regions that can bend and stretch. This allows the circuit board to adapt to battery assembly deformation while maintaining comprehensive voltage monitoring across all cells.

Inventive Principle:
Principle #30Flexible shells and thin films

3Adaptability or versatility

If the busbar module is designed with margins in voltage detection line length to accommodate battery assembly deformation, then the adaptability to deformation increases, but the overall module complexity and difficulty of attachment increases

Engineering Contradiction:
Improvefollowability to deformationVSAvoidmodule complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Instead of adding margins to all voltage detection lines, the patent applies thin portions with reduced protective layer thickness only at specific locations in the branch strips. This localized approach provides the necessary flexibility for deformation accommodation while keeping the overall module design simple and attachment straightforward.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3754753B1Busbar module
Publication Date: 2023.02.22 YAZAKI CORP
  • EP3754753B1 patent drawingFigure 1
  • EP3754753B1 patent drawingFigure 2
  • EP3754753B1 patent drawingFigure 3

AI summary

A busbar module includes: a circuit body having a flexible circuit board; busbars; and a holder. The circuit body has: conductor layers and protective layers to form a multiple-layered structure of wiring patterns; a band-shaped main strip to be located to extend in a stacking direction of cells; and a band-shaped branch strip branched from the main strip. The branch strip has: a bent portion extending in the stacking direction and having a bent shape around an axis crossing the stacking direction; and a connection portion disposed closer to an end of the branch strip than the bent portion and connected to the corresponding busbar. The bent portion has a thin-layer portion having a shape formed by removing, from the flexible circuit board, a part of the protective layers corresponding to a part of the conductor layers without being used as the wiring pattern in the branch strip.