EV Battery Casing Structure With Single-Seal Floor Integration

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Solution Overview

Problem

Existing electric vehicle battery compartments face issues of reduced interior volume, increased weight, and higher costs due to separate sealing requirements and additional components, which compromise the vehicle's structural rigidity and safety.

Innovation Solution

An electric vehicle body design that integrates the battery compartment within the vehicle structure, using a floor plate with overlapping edges under side members and a cover with overlapping sides, providing a single seal that meets IP67 standards, eliminating the need for a peripheral frame and top cover, thus maximizing volume and reducing components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the battery casing is designed with high strength to protect the battery, then safety is improved, but the weight of the vehicle increases

Engineering Contradiction:
Improvebattery protectionVSAvoidvehicle weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The battery casing is constructed from composite materials, specifically a plastic material (such as polypropylene or polyamide) reinforced with glass fibers or carbon fibers. This composite structure provides high strength and impact resistance comparable to metal casings while significantly reducing the weight, thus protecting the battery without increasing vehicle weight

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters by transitioning from traditional metal casings to reinforced plastic composites. By adjusting the fiber content (30-70% by weight), the casing achieves optimal balance between strength, weight, and cost, providing adequate protection while maintaining lightweight vehicle construction

Inventive Principle:
Principle #35Parameter changes

2Strength

If the battery casing is made from metal to ensure durability, then strength is improved, but the cost of manufacture increases

Engineering Contradiction:
Improvecasing strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The battery casing uses glass fiber or carbon fiber reinforced plastics that provide strength comparable to metal at lower cost. These composite materials can be molded directly into complex shapes using injection molding or compression molding, eliminating the need for expensive metal forming, welding, and assembly operations

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the fiber content parameter (30-70% by weight) to achieve the minimum required strength while minimizing material cost. This parameter adjustment allows the casing to meet durability requirements without using excessive amounts of expensive reinforcement materials

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the battery casing uses thick walls to provide protection, then safety is improved, but the volume available for battery cells decreases

Engineering Contradiction:
Improvebattery protectionVSAvoidbattery cell volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The high strength-to-weight ratio of glass fiber or carbon fiber reinforced plastics allows the casing to be made with thinner walls while maintaining equivalent protection levels to much thicker metal casings. This reduces the space consumed by the casing structure, increasing the volume available for energy-storing battery cells

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4532300B1Motor vehicle body comprising a casing for an electric traction battery
Publication Date: 2026.04.29 STELLANTIS AUTO SAS
  • EP4532300B1 patent drawingFigure 1~2
  • EP4532300B1 patent drawingFigure 3

AI summary

The invention relates to a body for an electric motor vehicle, comprising a floor plate (12), longitudinal side rail members (2), a battery casing positioned under the floor plate (12) and, below this casing, a casing cover (20), the floor plate (12) being fixed on each side to one of the longitudinal side rail members (2), these longitudinal side rail members (2) having a substantially horizontal underside face (34), the edges (36) of the floor plate (12) being superposed under the underside faces (34) of the longitudinal side rail members, the floor plate (12) and the edges (36) thereof making the vehicle body (38) watertight and sealed against fumes, and the sides of the cover (20) having a flat face (40) that is superposed under the floor plate edges (36), these together rendering the battery casing (44) watertight and impenetrable to dust.