Rear Bumper Beam Inversion for Vehicle Component Protection

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Solution Overview

Problem

Existing rear vehicle-body structures are inadequate in protecting vehicle components, such as battery units and fuel tanks, disposed under the rear floor from rear-end collision loads due to their susceptibility to damage from impact.

Innovation Solution

A rear vehicle-body structure design where the vertical center of the rear bumper beam is located below the vertical center of the rear side frames, incorporating load-absorbing parts and a fragile portion to absorb and distribute collision loads, ensuring the rear bumper beam receives the load and the side frames can bend and break to protect the components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the vertical center of the rear bumper beam is located above the vertical center of the rear side frame (conventional design), then the structure is simpler to manufacture, but the vehicle component under the rear floor is vulnerable to rear-end collision damage

Engineering Contradiction:
Improveprotection of vehicle componentVSAvoidstructural configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent inverts the conventional vertical arrangement by positioning the rear bumper beam below the rear side frame, rather than above it. This inverted configuration allows the rear bumper beam to effectively intercept and absorb rear-end collision loads before they reach the vehicle component disposed under the rear floor, thereby resolving the contradiction between protection reliability and structural simplicity.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The rear bumper beam acts as an intermediary protective element between the external collision load and the vulnerable vehicle component (battery unit or fuel tank). By positioning it below the rear side frame, it serves as a first line of defense that absorbs impact energy, preventing direct transmission of collision forces to the protected component.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the rear bumper beam is positioned lower to protect vehicle components, then collision load protection is improved, but the structural design becomes more complex

Engineering Contradiction:
Improvecollision load protectionVSAvoidstructural design
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the rear vehicle-body structure into distinct functional components: the rear bumper beam for collision load absorption, the rear side frames for structural support, and the vehicle component for protection. This segmentation allows each component to be optimized for its specific function while maintaining manufacturability through modular assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by giving different vertical positions to different structural elements based on their functional requirements. The rear bumper beam is positioned lower for optimal collision protection, while the rear side frame maintains its conventional position for structural integrity, creating a differentiated vertical arrangement that optimizes both protection and manufacturability.

Inventive Principle:
Principle #3Local quality

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

Enhances the protection of vehicle components under the rear floor by temporarily receiving and managing rear-end collision loads, allowing the side frames to absorb and distribute the impact effectively, thus reducing damage to critical components like fuel tanks and battery units.

Implementation Method 1

load absorbing parts extending from left and right ends of the rear bumper beam toward a vehicle front side

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

protecting a vehicle component disposed under a rear floor against a rear-end collision load

Methodology Applied
Scientific EffectImpact Force: Impact Force

Implementation Method 3

a fragile portion relative to a load applied in a front-rear direction on an upper side of a border between a front-side part and a rear-side part of the rear side frame

Methodology Applied
Scientific EffectFracture Mechanics: Fracture Mechanics

Data Source

PatentEP3747704B1Rear vehicle-body structure of a vehicle, vehicle-body structure of a vehicle, and vehicle
Publication Date: 2022.08.10 MAZDA MOTOR CORP
  • EP3747704B1 patent drawingFigure 1
  • EP3747704B1 patent drawingFigure 2
  • EP3747704B1 patent drawingFigure 3

AI summary

Provided is a rear vehicle-body structure of a vehicle that can enhance the performance of protecting a vehicle component 15 disposed under a rear floor 12 against a rear-end collision load, wherein the rear vehicle-body structure includes a rear bumper reinforcement 37 having a rear bumper beam 33 extending in a vehicle width direction along a rear bumper and load absorbing parts 32 extending from left and right ends of the rear bumper beam 33 toward a vehicle front side, and rear side frames 20 extending in a vehicle front-rear direction respectively along left and right side portions of a rear floor and coupled at rear ends to front ends of the load absorbing parts 32, a vehicle component being disposed under the rear floor. A vertical center of the rear bumper beam 33 is located below a vertical center of the rear side frame 20.