Rear Axle Controlled Displacement for Impact Safety

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Solution Overview

Problem

Current rear axle designs with deformable crossmembers in vehicles are inadequate for withstanding high-speed rear impacts, as they fail to prevent the longitudinal displacement of suspension arms, leading to joint breakage and potential damage to critical components like the gasoline tank, while existing reinforcement solutions are either too heavy or incompatible with modern vibration filtration requirements.

Innovation Solution

Incorporating blocking means with a projecting end and a frangible orifice in the reinforcement element of the chassis, which allows for controlled longitudinal displacement and energy absorption during impacts, and features side walls for lateral support, enabling the suspension arm to maintain stability and absorb impact energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rear axle is reinforced with a rigid joint and transmission universal joint to prevent longitudinal displacement during impact, then the resistance to rear impact is improved, but the vibration filtration capability deteriorates and the weight increases

Engineering Contradiction:

Improveresistance to rear impactVSAvoidvibration filtration capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The suspension arm is designed with a movable articulation joint that allows dynamic movement during normal operation to filter vibrations, while during rear impact the joint can break in a controlled manner to limit longitudinal displacement. This dynamic design enables the system to adapt its behavior based on the severity of the applied force.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The articulation joint is designed with specific geometric parameters (arm length, joint positioning) that allow it to function as a vibration filter under normal conditions but fail in a controlled manner during high-speed rear impact. The breakage of the joint changes the structural parameters from a flexible connection to a limited displacement mechanism.

Inventive Principle:

Principle #35Parameter changes

2Reliability

Engineering Contradiction:

Improveresistance to rear impactVSAvoidweight of rear axle

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The articulation joint is designed as a sacrificial component that can break during severe rear impact to protect the vehicle structure. Instead of making the entire rear axle rigid and heavy, a specific component is designed to fail in a controlled manner, providing impact protection without requiring continuous reinforcement of the entire assembly.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The rear axle system is segmented into separate functional components: the deformable crossmember, the suspension arm, and the articulation joint. This segmentation allows the articulation joint to be optimized specifically for impact protection while other components maintain their vibration filtration capabilities, avoiding the need to reinforce the entire assembly.

Inventive Principle:

Principle #1Segmentation

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

The solution effectively blocks transverse displacement and absorbs impact energy, enhancing vehicle safety during rear impacts by preventing damage to critical components without increasing weight or volume, thus meeting stringent safety regulations.

Implementation Method 1

the orifice is formed by a frangible zone of said reinforcement... allowing the front part of the suspension arm to maintain a longitudinal displacement (x) to gradually absorb the energy due to the impact

Methodology Applied

Scientific EffectEnergy absorption through deformation: Deformation

Implementation Method 2

the blocking means comprise side walls adapted to form lateral bearing surfaces at the front part of the suspension arm during said impact

Methodology Applied

Scientific EffectMechanical constraint through bearing surfaces: Friction

Data Source

PatentEP3676115B1Vehicle comprising a rear wheelset with controlled longitudinal displacement in the event of a rear impact

Publication Date: 2023.04.19 STELLANTIS AUTO SAS

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AI summary

The invention relates to a vehicle (1) which comprises a chassis (13) to which there is attached a rear wheelset (3) with a deformable crossmember (31), the wheeelset (3) comprising, on each side of the deformable crossmember (31), a longitudinal suspension arm (32) comprising an articulation (34) in the forward part (322) of the suspension arm (32), the chassis (13) comprising a structural element positioned in the forward continuation of the suspension arm (32) and designed to extend opposite, and to limit the longitudinal displacement (x) of, the forward part (322) of the suspension arm (32), such a longitudinal displacement occurring in an impact on the rear of the vehicle (1) which causes said articulation (34) to break, the vehicle comprising blocking means designed to block the transverse displacement (y) of the forward part (322) of the suspension arm (32) in said impact.