Bumper Assembly with Deployable Fins for Variable Stiffness
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Solution Overview
Problem
Vehicle bumpers face a design challenge in achieving the right stiffness for both low-speed damageability and pedestrian impact protection, as existing standards create competing design principles that require different stiffness levels depending on vehicle speed.
Innovation Solution
A bumper assembly with a carrier and crush cans that includes rotatable fins, which can change their position based on vehicle speed, allowing for variable stiffness by reinforcing the bumper at low speeds and reducing stiffness at higher speeds to absorb energy during pedestrian impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bumper stiffness is increased to prevent damage at low speed, then low speed damageability is improved, but pedestrian impact energy absorption deteriorates
Solution Approach 1:
The bumper system transitions from a static stiffness structure to a dynamic one by incorporating deployable fins that can change their configuration based on impact conditions. The fins are stored in a retracted position during normal operation and deploy to specific angles (e.g., 45 degrees) upon detecting an impact, thereby dynamically adjusting the bumper's stiffness and energy absorption characteristics to match the impact scenario.
Solution Approach 2:
The system changes the physical parameter of stiffness by altering the geometric configuration of the bumper structure. By deploying fins at specific angles, the effective stiffness of the bumper is modified without changing the material properties. This allows the same bumper structure to provide high stiffness for low-speed vehicle-to-vehicle impacts and low stiffness for high-speed pedestrian impacts.
2Object-affected harmful factors
If the bumper stiffness is decreased to absorb energy during pedestrian impact, then pedestrian protection is improved, but low speed damageability deteriorates
Solution Approach 1:
The bumper system uses deployable fins that can be positioned in different configurations to provide variable stiffness. During pedestrian impacts, the fins are deployed to create a more compliant structure that absorbs impact energy, while during low-speed vehicle impacts, the fins are retracted to provide maximum structural stiffness and damage prevention.
Solution Approach 2:
The bumper structure is segmented into multiple functional components: the main carrier structure and separate deployable fins. This segmentation allows independent control of different structural elements, enabling the fins to be deployed or retracted based on the type of impact detected, thereby optimizing performance for different impact scenarios without compromising the overall structural integrity.
3Device complexity
If a single bumper structure is used for both low speed and high speed impacts, then device complexity is reduced, but adaptability to different impact conditions deteriorates
Solution Approach 1:
The bumper is divided into the carrier structure and separate deployable fin components. This segmentation enables the system to maintain a relatively simple base structure while adding adaptive capability through the fins. The fins can be independently controlled to respond to different impact conditions, providing versatility without significantly complicating the overall bumper architecture.
Solution Approach 2:
The deployable fins serve multiple functions: they act as structural reinforcement during low-speed impacts when retracted, and as energy-absorbing elements during pedestrian impacts when deployed. This multi-functionality allows a single additional component to address both low-speed damageability and pedestrian protection requirements, improving adaptability without proportionally increasing complexity.
Data Source
AI summary
A bumper includes a carrier having a wall extending along a longitudinal axis, and a first leg and a second leg extending away from the wall in a first direction. A plurality of fins are movably attached to the carrier between the first leg and the second leg, and are spaced from each other the longitudinal axis. The fins may be moved to a deployed position to reinforce the bumper to improve low-speed damageability of the bumper, and may be moved to an inactive position, which may allow a fascia to more easily deform relative to the deployed position to provide energy absorption for pedestrian impacts.