Bumper Cavity Absorbs Pedestrian Impact Energy
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Solution Overview
Problem
Vehicles with high bumper heights, such as light duty trucks and SUVs, pose a risk of uneven impact on pedestrians' legs during collisions due to ground clearance requirements, necessitating a design that balances energy management with pedestrian protection while maintaining adequate clearance.
Innovation Solution
A bumper assembly with a rigid metal bumper beam and a plastic bumper that includes a cavity aligned with the pedestrian's knee, designed to collapse and absorb impact energy, combined with a grille reinforcement system that distributes force across the leg to reduce relative movement between the femur and tibia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the bumper height is increased to provide ground clearance for light duty trucks and SUVs, then the vehicle can clear speed bumps, curbs, and rough roads, but the impact force on the pedestrian's legs becomes uneven and more severe
Solution Approach 1:
The bumper incorporates a cavity structure with varying thickness - thinner at the top and thicker at the bottom - to create localized energy absorption zones. This allows different parts of the bumper to serve different functions: the upper portion maintains height for ground clearance while the lower cavity portion absorbs impact energy to protect pedestrians' legs during collisions
Solution Approach 2:
The bumper design changes the physical parameters of the bumper structure by introducing a cavity that alters the thickness distribution. The cavity thickness varies from top to bottom, creating a gradient structure that modifies how impact forces are distributed and absorbed, thereby reducing leg injury risk while maintaining overall bumper height
2Loss of energy
If the bumper is designed to absorb impact energy through a cavity structure, then pedestrian leg impact energy is managed, but the bumper must be positioned at a height that maintains ground clearance
Solution Approach 1:
The cavity structure concentrates energy absorption capabilities at specific locations within the bumper - particularly at the bottom portion where impact forces are most severe. This localized quality allows the bumper to maintain overall height for ground clearance while creating specific zones optimized for energy absorption during pedestrian impacts
Solution Approach 2:
Instead of increasing bumper height in the vertical dimension to improve protection, the invention introduces a cavity dimension that creates internal volume for energy absorption. This dimensional approach allows the bumper to maintain external height requirements while adding internal structural features that manage impact energy
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 manages pedestrian leg impact energy by absorbing force through the bumper cavity and distributing it across the leg, reducing injury risk while maintaining vehicle ground clearance.
Implementation Method 1
The bumper defines a cavity enclosed by the bumper. The cavity is elongated in the cross-vehicle direction. At least a portion of the cavity at the lower end may be greater than 30 mm in a vehicle-rearward direction.
Data Source
AI summary
A bumper assembly includes a bumper beam elongated in a cross-vehicle direction and a bumper that is plastic. The bumper is elongated in the cross-vehicle direction and is affixed to the bumper beam. The bumper beam is rigid relative to the bumper. The bumper defines a cavity enclosed by the bumper. The cavity is elongated in the cross-vehicle direction.