Motor Vehicle Front End Upper Crosspiece Deformation
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Solution Overview
Problem
Current passive safety systems in motor vehicle front ends, while aiming to minimize pedestrian injury in frontal collisions, require enhancement to effectively absorb impact energy and reduce pelvic area injuries without increasing component count or weight.
Innovation Solution
A motor vehicle front end design featuring a support structure with a collapsible upper crosspiece and a plastic-covered metal rear portion, along with deformable connection elements forming a virtual hinge, allows for progressive deformation and energy absorption during impacts, enabling increased space for bonnet deformation and reduced pedestrian injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid upper crosspiece is used to support the radiator, then structural strength is improved, but pedestrian safety deteriorates due to limited bonnet deformation space
Solution Approach 1:
The upper crosspiece is divided into two distinct portions: a front collapsible portion and a rear rigid portion. The front portion is designed to deform plastically under impact to create bonnet deformation space, while the rear portion maintains structural integrity for radiator support. This segmentation allows the single crosspiece to simultaneously provide both strength and safety functions.
Solution Approach 2:
Different portions of the crosspiece are assigned different mechanical properties: the front portion has low yield strength for energy absorption and deformation, while the rear portion has high yield strength for structural support. This local differentiation of material properties enables the crosspiece to perform contrasting functions in different spatial zones.
2Object-affected harmful factors
If active safety systems with actuators and air bags are used, then pedestrian safety is improved, but cost and device complexity increase
Solution Approach 1:
The front portion of the crosspiece is pre-designed with controlled plastic deformation characteristics to automatically absorb impact energy during pedestrian collisions. This passive energy absorption mechanism eliminates the need for active safety systems requiring sensors, actuators, and control units, significantly reducing component count while maintaining safety effectiveness.
Solution Approach 2:
The collapsible crosspiece structure autonomously performs the safety function through its inherent plastic deformation properties when impacted. The system does not require external control, power supply, or active intervention - it self-activates upon impact and automatically creates deformation space, replacing complex active safety systems with a simple passive mechanical solution.
3Loss of energy
If the entire crosspiece is made collapsible to improve pedestrian safety, then energy absorption is improved, but structural strength deteriorates
Solution Approach 1:
The crosspiece is segmented into front and rear portions with distinct mechanical functions. The front portion is designed for plastic deformation and energy absorption, while the rear portion maintains high strength for structural support. This segmentation allows the system to achieve both energy absorption and structural integrity simultaneously.
Solution Approach 2:
The rear portion of the crosspiece is designed with high yield strength to maintain structural rigidity and support the radiator, while the front portion has reduced yield strength optimized for energy absorption. This local differentiation ensures that strength is concentrated where needed while allowing controlled deformation in the impact zone.
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 design effectively absorbs impact energy, reduces pedestrian pelvic injuries, and is cost-effective with minimal modifications to existing components, utilizing a simple and efficient passive safety system.
Implementation Method 1
two plastically deformable, lateral portions which define a virtual hinge
Implementation Method 2
the deformation of which is limited by the presence of the aforementioned crosspiece underneath
Data Source
Figure 1
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Figure 3
AI summary
A motor vehicle front end has a frame (14), which supports a heat exchanger and has an upper horizontal crosspiece (19) connected to two uprights (15) by means of connection elements (24), which are plastically deformable so as to allow the upper horizontal crosspiece (19) to be lowered in the event of an accident; the upper horizontal crosspiece (19) comprises a rigid rear portion (23) and a plastically deformable, front portion (21) which is made of plastic material and is fixed to the rigid rear portion (23).