Motor Vehicle Chassis Strut for Side Impact Force Distribution

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Solution Overview

Problem

In motor vehicle chassis, lateral impacts can cause significant deformation and risk of damage to the tunnel and floor, endangering passenger safety, while existing solutions either increase vehicle mass or complicate assembly.

Innovation Solution

A motor vehicle chassis design featuring a strut inclined relative to the crosspiece and tunnel, distributing the thrust force into two elementary forces applied at longitudinally distant points, stabilizing the tunnel and preventing deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the crossmember is made to conform to the tunnel profile to reinforce the floor, then passenger safety is improved, but the structural complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvepassenger safetyVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The crossmember is divided into multiple segments or zones along its length, with each segment having a different profile configuration. The central portion conforms to the tunnel profile to provide reinforcement, while the end portions have simplified geometries for easier manufacturing and assembly. This segmentation allows the structure to achieve safety goals without requiring the entire crossmember to be complex.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The crossmember profile is optimized locally rather than uniformly throughout. The portion that contacts or is near the tunnel is shaped to conform to the tunnel profile for maximum reinforcement effect, while other portions have simpler cross-sections. This local quality approach provides enhanced protection exactly where needed without unnecessarily increasing overall structural complexity.

Inventive Principle:
Principle #3Local quality

2Reliability

If additional reinforcement elements are added to the crossmember-tunnel junction, then tunnel degradation is reduced, but vehicle mass increases

Engineering Contradiction:
Improvetunnel integrityVSAvoidvehicle mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The reinforcement function is merged into the crossmember itself through its profile configuration rather than being a separate element. The crossmember's geometry is designed to naturally distribute and redirect impact forces away from the tunnel, combining the structural support and impact protection functions into a single integrated component, thereby avoiding additional mass from separate reinforcement elements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The crossmember's profile parameters (cross-sectional shape, thickness distribution, curvature) are optimized to achieve maximum reinforcement effect with minimum mass. By carefully controlling these geometric parameters, the design achieves effective tunnel protection without requiring excessive material, thus avoiding unnecessary weight increase.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the crossmember is designed to promote localized breakage to prevent damage propagation, then passenger compartment protection is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvedamage containmentVSAvoidbreakage control precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The crossmember is pre-designed with predetermined weak zones or stress concentration features that are strategically positioned to initiate controlled breakage at specific locations during impact. These preliminary design features guide the fracture path in advance, ensuring that when breakage occurs, it happens in a controlled manner that prevents damage propagation to the passenger compartment without requiring high manufacturing precision during actual impact events.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3810490B1Motor vehicle chassis, comprising means for distributing against a tunnel a force applied by a crossmember in the event of a side impact
Publication Date: 2023.09.13 STELLANTIS AUTO SAS
  • EP3810490B1 patent drawingFigure 1~2(b)
  • EP3810490B1 patent drawingFigure 3~4

AI summary

The invention relates to a motor vehicle chassis (3), comprising an underbody frame covered by a floor (7) secured to the frame. The frame comprises side rails (4) and at least one longitudinal tunnel (5) placed at a transverse distance from one such rail (4) to which the tunnel (5) is connected via a crossmember (6) which is secured by one of the ends (6a) thereof to the tunnel (5) and by the other end (6b) thereof to the rail (4). The crossmember (6) forms a first member for transmitting to the tunnel (5) a first thrust force (EP1) generated by an impact applied laterally against the chassis (3). A strut (8) is jointly secured by the respective ends (8a, 8b) thereof to the crossmember (6) and to the tunnel (5), and is inclined with respect to the main direction in which they extend in a plane parallel to the floor (7). The strut (8) forms a second member for transmitting to the tunnel (5) a second thrust force (EP2) generated by said impact and transmitted to the strut (8) by the crossmember (6).