Pedestrian Bumper Spring Element Rebound Control
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Solution Overview
Problem
Current bumper arrangements for passenger cars do not effectively manage the displacement of a pedestrian's lower legs during a collision, leading to inadequate energy absorption and inefficient rebound, which can result in increased injury.
Innovation Solution
Incorporating a spring element on the lower crossmember of the bumper arrangement that extends over its width, featuring a wavy cross-section and adjustable stiffness, to facilitate elastic deformation and controlled rebound, ensuring the pedestrian's torso is displaced towards the hood while their lower legs follow suit, thereby reducing the risk of injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lower crossmember without spring elements is used, then the structure is simple and manufacturing is easy, but the rebound effect is insufficient and pedestrian safety is compromised
Solution Approach 1:
The patent introduces spring elements with specific stiffness values (e.g., 50-200 N/mm) and geometric parameters (wire diameter, mean coil diameter, number of active coils) to optimize the rebound effect. By adjusting these parameters, the lower crossmember achieves controlled elastic deformation that safely redirects pedestrian lower legs during impact, resolving the contradiction between safety performance and structural simplicity.
2Force
If the spring element is made very stiff to maximize rebound, then the rebound effect is enhanced, but the spring element may cause additional injury due to excessive force
Solution Approach 1:
The patent specifies optimal stiffness ranges for the spring elements (50-200 N/mm) to balance rebound effectiveness with safety. This parameter optimization ensures that the spring generates sufficient rebound force to redirect the pedestrian's lower legs away from the bumper, while simultaneously limiting the force to avoid causing additional injury during the brief impact duration.
3Loss of energy
If the spring element deforms plastically to absorb energy, then energy absorption is increased, but the rebound effect is reduced
Solution Approach 1:
The patent designs the spring elements with carefully selected material properties and geometric parameters to operate primarily in the elastic deformation range during pedestrian impact. By controlling the spring stiffness and dimensions, the system achieves sufficient energy absorption through elastic deformation while maintaining the rebound force necessary to safely redirect the pedestrian's lower legs, avoiding the harmful effect of plastic deformation.
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 spring element enhances the bumper's energy absorption capabilities, allowing for optimal displacement of the pedestrian's torso and legs, minimizing the opening angle between the legs and reducing the risk of injury by releasing deformation energy elastically, thus improving the safety and effectiveness of the bumper arrangement.
Implementation Method 1
the collision-related deformation of the spring element lies at least predominantly in the range of elastic deformation, i.e. the proportion of plastic deformation is very low. As a result, the spring element initially deforms elastically under the action of a force and the spring element subsequently moves back in the direction of the initial state it had before the collision, releasing the deformation energy introduced during the force transmission into the spring element.
Data Source
AI summary
A bumper arrangement of a passenger car has an upper and a lower load path. A spring element is provided on the transverse support of the lower load path, which, in the event of a collision of a pedestrian with the passenger car, exerts an additional force on the lower leg of the pedestrian, so as to support the movement of the pedestrian in the direction of the front hood of the passenger car.