Underfloor EV Battery Mounting With Profiled Crossmember Tabs

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Solution Overview

Problem

The existing methods for fixing high-voltage electric batteries under vehicles are inefficient, requiring mechanical reinforcement of the rear central crossmember, which increases manufacturing time and costs due to the lack of mechanical resistance and stiffness provided by standard fixing lugs.

Innovation Solution

A robust fixing system is implemented using bridges with profiled tabs that extend along the rear central crossmember, providing extensive surface contact and stiffness, eliminating the need for additional reinforcement by integrating the bridges into the crossmember's structure, and securing the battery with screws through bosses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If standard fixing lugs are used to secure the battery, then the battery can be fixed to the cross members, but the mechanical resistance and stiffness are insufficient requiring additional reinforcement

Engineering Contradiction:
Improvemechanical resistanceVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The fixing system is divided into modular components: standard fixing lugs for basic attachment, and optional reinforcing elements that can be added only where and when needed. This segmentation allows the system to provide adequate strength without requiring all vehicles to have complex reinforced structures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of reinforcing the entire cross member structure uniformly, reinforcement is applied partially only at specific locations where mechanical resistance is insufficient. This partial action approach provides the necessary strength enhancement without the excessive complexity and cost of complete structural reinforcement.

Inventive Principle:
Principle #16Partial or excessive action

2Strength

If the rear central cross member is mechanically reinforced with additional elements, then the battery can be securely held, but manufacturing time increases

Engineering Contradiction:
Improvestructural strengthVSAvoidmanufacturing speed
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The reinforcement system is segmented into separate attachable components rather than being integrated into the cross member as a single complex piece. This allows the base cross member to be manufactured quickly using standard processes, with reinforcement elements added only when and where needed through simpler secondary operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Reinforcing elements are designed to be pre-fabricated as separate components and attached to the cross member after its primary manufacturing is complete. This preliminary preparation of reinforcement components allows the main cross member to be produced at high speed without interruption, maintaining manufacturing productivity while still enabling structural strengthening.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If reinforcing elements are added to the cross member, then the battery fixing becomes more robust, but manufacturing costs increase

Engineering Contradiction:
Improvefixing system reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Reinforcement is applied with local quality - only at specific locations on the cross member where structural analysis shows it is necessary for reliable battery fixing. This localized approach ensures the fixing system achieves the required reliability without incurring the excessive manufacturing costs that would result from uniform reinforcement throughout the entire structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The reinforcement strategy uses partial action by providing strengthening elements only where mechanically necessary rather than applying reinforcement uniformly. This allows the manufacturer to balance reliability requirements with cost considerations, adding reinforcement only to the extent needed to achieve adequate fixing system reliability.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4129726B1Vehicle provided with a system for attaching an electric battery beneath a floor
Publication Date: 2024.05.29 RENAULT SA
  • EP4129726B1 patent drawingFigure 1~2
  • EP4129726B1 patent drawingFigure 3~4
  • EP4129726B1 patent drawingFigure 5~6

AI summary

The invention relates to a vehicle comprising a high-voltage electric battery (9) and a rear floor (100) including a rear central crossmember (5), the electric battery (9) being attached to two brackets (112, 113) fixed to the rear central crossmember (5). According to the invention, the rear central crossmember (5) has a swollen area extending along said crossmember (5), and each bracket (112, 113) has a first attachment area in the form of a profiled tab enclosing said swollen area by establishing an extensive surface contact therewith.