Slit End Plate Battery Pack Frame for Welded Sealing Stability

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Solution Overview

Problem

Existing battery pack frames suffer from welding defects due to differences in frame lengths, leading to unstable fixation and electrical connections, and potential contamination from foreign matter ingress.

Innovation Solution

A battery pack design featuring end plates with slits allowing flexible deformation and a pressing jig to ensure close coupling with the frame, using resistance welding for secure attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the length of U frame is longer than the length of top frame, then the U frame can accommodate more battery cells, but the end frame cannot make close contact with the top frame causing sealing failure

Engineering Contradiction:
Improvenumber of battery cellsVSAvoidsealing performance
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The end frame is designed with a variable cross-sectional shape that allows it to dynamically adjust its geometry. Specifically, the end frame can change its shape along the longitudinal direction to accommodate the length difference between the U frame and top frame, enabling close contact and proper sealing while maintaining the ability to accommodate more battery cells.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cross-sectional shape parameters of the end frame are made changeable rather than fixed. The end frame's cross-section can vary along its length, allowing different sections to have different shapes that optimize both the accommodation of battery cells and the sealing contact with the top frame, thus resolving the contradiction between quantity and sealing reliability.

Inventive Principle:
Principle #35Parameter changes

2Strength

If rigid frame structure is used, then structural strength is improved, but welding defects occur due to length differences between frames

Engineering Contradiction:
Improvestructural strengthVSAvoidwelding quality
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The end frame transitions from a completely rigid structure to a dynamic structure that can change its cross-sectional shape. This allows the frame to adapt to length differences between the U frame and top frame during assembly, eliminating gaps that would cause welding defects while maintaining overall structural strength through its optimized variable geometry.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The geometric parameters of the end frame, particularly its cross-sectional shape, are made variable rather than fixed. This enables the frame to be manufactured with standard dimensions and then dynamically adjust its shape during assembly to achieve proper fit and welding quality, eliminating the need for precise pre-control of frame lengths.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If precise position control is required during welding, then sealing quality is improved, but process complexity and time increase

Engineering Contradiction:
Improvesealing qualityVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The end frame is pre-designed with variable cross-sectional shape characteristics that enable it to automatically adapt to the top frame during assembly. This preliminary design eliminates the need for complex real-time position control during welding, as the frame's inherent shape variability allows it to self-adjust to achieve proper sealing contact.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The dynamic shape-changing capability of the end frame allows it to automatically compensate for dimensional variations during assembly. This eliminates the need for time-consuming precise position control operations, as the frame can dynamically adjust its geometry to achieve proper fit and sealing without requiring complex control systems or extended assembly time.

Inventive Principle:
Principle #15Dynamics

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

Ensures stable sealing against foreign substance ingress, improves processability, and enhances the reliability of electrical connections by maintaining a stable stack structure.

Implementation Method 1

a pressing jig configured to manufacture the battery pack

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

using resistance welding for secure attachment

Methodology Applied
Scientific EffectResistance Welding: Welding

Data Source

PatentEP3848994B1Battery pack comprising battery pack frame capable of preventing welding defect and pressing jig for preparing the same
Publication Date: 2025.10.01 LG ENERGY SOLUTION LTD
  • EP3848994B1 patent drawingFigure 1
  • EP3848994B1 patent drawingFigure 2(a)~2(b)
  • EP3848994B1 patent drawingFigure 3(a)~3(b)

AI summary

Disclosed herein is a battery pack comprising a battery module comprising a plurality of battery cells or a unit module comprising the plurality of battery cells; a battery pack frame body comprising a base plate on which the battery module is mounted, and a first side plate and a second side plate connected to the base plate and disposed in opposite directions to each other; a top frame coupled to an upper portion of the pack case body; and a first end plate and a second end plate electrically connected to electrode terminals of the battery module, wherein at least one of the first end plate and the second end plate is configured to form slits.