Battery Pack Double Shear Connection for Stable Cell Carrier Mounting

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Solution Overview

Problem

Existing battery packs for electrical devices lack a robust and efficient mechanism for securing and connecting battery cells, leading to potential disconnection and instability during use.

Innovation Solution

A battery pack design featuring a double shear connection system using threaded fasteners that pass through aligned screw bosses on both the upper and lower housing portions and the battery cell carrier, ensuring secure attachment and electrical communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single shear connection is used to attach the battery cell carrier to the housing, then the device complexity is reduced, but the reliability and stability of the connection deteriorates leading to potential disconnection during use

Engineering Contradiction:
Improveconnection stabilityVSAvoidconnection structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The connection structure is segmented into multiple shear planes by introducing intermediate connector screw bosses between the upper housing portion and the battery cell carrier. This segmentation allows the single fastener to create multiple shear conditions, distributing the load and improving reliability without requiring additional fasteners or complex assembly steps.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connector screw bosses act as intermediary elements that facilitate the double shear connection. These boss features provide additional connection points that enable the fastener to engage with both the upper housing portion and the battery cell carrier while creating intermediate shear planes, thereby enhancing connection stability without increasing overall structural complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If threaded fasteners are used to secure the battery cell carrier, then the connection strength is improved, but the manufacturing precision requirements increase due to alignment of multiple screw bosses

Engineering Contradiction:
Improveconnection strengthVSAvoidscrew boss alignment precision
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

Multiple screw bosses (outer screw boss, inner screw boss, and connector screw boss) are merged into a single alignment system that accommodates the threaded fastener. This merging approach allows the fastener to engage all bosses simultaneously through a single insertion action, reducing the cumulative alignment precision requirements compared to multiple separate fastening operations.

Inventive Principle:
Principle #5Merging (Combining)

3Duration of action of stationary object

If a robust connection system with multiple screw bosses is implemented, then the durability and anti-disconnection capability are enhanced, but the ease of manufacture deteriorates due to additional machining operations

Engineering Contradiction:
Improveconnection durabilityVSAvoidmanufacturing ease
Core Design Contradiction:
Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The connection interface is segmented into multiple functional zones (outer housing connection, inner housing connection, and carrier connection) that can be manufactured independently and then assembled. This segmentation allows each screw boss to be created using standard machining operations on respective components, avoiding the need for complex multi-operation machining of a single integrated structure.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4239770B1Battery pack with double shear connection
Publication Date: 2025.10.01 MILWAUKEE ELECTRIC TOOL CORP
  • EP4239770B1 patent drawingFigure 1
  • EP4239770B1 patent drawingFigure 2A
  • EP4239770B1 patent drawingFigure 2B

AI summary

A battery pack is configured to be coupled to an electrical device. The battery pack includes a plurality of battery cells, a battery cell carrier to support the battery cells, a housing having an upper housing portion. The battery cell carrier having a plurality of connector screw bosses. The upper housing portion having an outer screw boss on each lateral side and a respective inner screw boss formed on an inner surface of the upper housing portion. The upper housing portion is connected to the battery cell carrier with a plurality of threaded fasteners each extending through one of the outer screw bosses, a respective one of the plurality of connector screw bosses, and a respective inner screw boss creating a double shear condition on each side of the respective connector screw boss.