Retractable Bumper Assembly for Pedestrian Leg Impact Absorption
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Solution Overview
Problem
Vehicles with high bumper heights, such as light duty trucks and SUVs, face challenges in managing pedestrian leg impact energy while maintaining ground clearance, leading to uneven impact forces on the femur and tibia during vehicle-pedestrian collisions.
Innovation Solution
A retractable bumper assembly with an actuator system that includes a rod, bracket, and spring mechanism, allowing the bumper to retract rearward during impacts, absorbing energy and reducing force transmission to pedestrians, controlled by a vehicle computer based on speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the bumper height is increased to provide ground clearance, then the vehicle can clear speed bumps and obstacles, but the impact force on pedestrian legs becomes uneven and more severe
Solution Approach 1:
The bumper assembly incorporates a retractable mechanism with actuators that dynamically adjust the bumper position based on vehicle speed. At low speeds, the bumper retracts to reduce impact force on pedestrians, while at higher speeds it maintains its position for ground clearance. This dynamic adjustment resolves the contradiction between maintaining fixed bumper height for ground clearance and reducing impact force for pedestrian safety.
Solution Approach 2:
The system changes the physical state and position parameters of the bumper based on operating conditions. The actuator mechanism modifies the bumper's position parameter from a fixed state to a variable state, allowing it to retract at low speeds and extend at high speeds, thereby adapting the impact characteristics to different speed conditions while maintaining ground clearance capability.
2Object-affected harmful factors
If the bumper is made retractable to reduce impact force, then pedestrian safety improves, but the device complexity increases
Solution Approach 1:
The bumper assembly is segmented into multiple components including the bumper body, retractable mechanism, actuators, and control system. This segmentation allows each component to perform its specific function independently, making the complex system more manageable and maintainable while enabling the retractable functionality needed for pedestrian safety.
Solution Approach 2:
The actuator serves as an intermediary mechanism between the control system and the bumper. It translates control signals into physical motion to retract or extend the bumper, thereby mediating the complexity between the simple control logic and the mechanical bumper structure, making the overall system more manageable.
3Loss of energy
If the actuator is disengaged to allow bumper retraction, then energy absorption during impact improves, but the bumper position stability deteriorates
Solution Approach 1:
The system dynamically adjusts the engagement state of the actuator based on vehicle speed. At low speeds, the actuator is disengaged to allow bumper retraction and energy absorption during pedestrian impacts. At higher speeds, the actuator engages to maintain stable bumper position. This dynamic state change resolves the contradiction between energy absorption and position stability.
Solution Approach 2:
The control system receives feedback about vehicle speed and automatically adjusts the actuator engagement state accordingly. This feedback mechanism ensures the bumper is in the correct state (retracted or stable) based on current operating conditions, resolving the contradiction between energy absorption needs at low speeds and position stability needs at high speeds.
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 system effectively manages pedestrian leg impact energy by retracting the bumper to absorb energy, reducing injury risk and complying with regulatory standards like GTR and NCAP, while maintaining vehicle functionality.
Implementation Method 1
A spring is on the rod between the bumper and the bracket. The spring biases the bumper away from the bracket.
Data Source
AI summary
A vehicle includes a bumper assembly. The bumper assembly includes a bumper, a rod fixed relative to the bumper and elongated along an axis, and a bracket spaced from the bumper along the axis of the rod. The bracket movably receives the rod. An actuator is supported by the bracket and is releasably engageable with the rod. A spring is on the rod between the bumper and the bracket. The spring biases the bumper away from the bracket.