Frangible Suspension Lever for Offset Crash Protection
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Solution Overview
Problem
During an offset frontal vehicle impact, the wheel can intrude into the passenger compartment due to the rotation of the wheel relative to the suspension arm, causing the wheel to become trapped between the bumper beam and the wheel well, which is a concern in small-offset rigid-barrier frontal crash tests.
Innovation Solution
A vehicle suspension system design featuring a lever that extends through a bushing connected to the suspension arm, with frangible fasteners that break upon impact, allowing the lever, bushing, and suspension arm to release from the vehicle frame, directing the force rearward and reducing wheel intrusion into the cabin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suspension arm is rigidly connected to the vehicle frame, then the suspension system maintains structural stability, but the wheel may intrude into the passenger compartment during offset frontal impact
Solution Approach 1:
The connection between the suspension arm and vehicle frame is divided into two segments: a lever component connected to the suspension arm, and a frangible fastener connecting the lever to the vehicle frame. This segmentation allows the system to maintain structural integrity during normal operation while enabling controlled separation during impact to prevent wheel intrusion.
Solution Approach 2:
The frangible fastener is pre-configured with controlled break points that will fail at predetermined impact forces. This preliminary preparation ensures that when offset frontal impact occurs, the fastener breaks automatically to redirect the wheel rearward, preventing intrusion into the passenger compartment without requiring active control systems.
2Ease of operation
If the wheel is allowed to rotate freely relative to the suspension arm, then the suspension system provides normal steering functionality, but the wheel becomes trapped between the bumper beam and wheel well during impact
Solution Approach 1:
The system transitions from a static rigid connection to a dynamic conditional connection. During normal operation, the frangible fastener maintains a rigid connection allowing steering rotation. During impact, the fastener breaks, allowing the suspension arm and wheel to rotate freely rearward, converting the harmful trapping effect into a protective rearward motion.
Solution Approach 2:
The connection strength parameter changes from high (rigidly fastened) during normal operation to low (broken connection) during impact. The frangible fastener is designed with specific material properties and geometry that maintain strength under normal steering loads but fail at impact force levels, thereby changing the system's mechanical parameters based on operational conditions.
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 reduces the likelihood of wheel intrusion into the occupant cabin by redirecting the force of the impact through the lever, bushing, and suspension arm, ensuring the wheel is driven rearward, thus minimizing the risk of cabin intrusion during a small-offset rigid-barrier frontal crash test.
Implementation Method 1
The fastener is configured to break before the lever and the bushing when the lever is impacted by a small-offset rigid-barrier during a small-offset rigid-barrier frontal crash test
Data Source
AI summary
A vehicle includes a vehicle frame and a suspension arm. A bushing is connected to the suspension arm. A lever extends through the bushing. A fastener is fastened to the lever and the vehicle frame. When the lever is impacted by a rigid barrier of a small-offset rigid-barrier (SORB) frontal impact test, the lever breaks the fastener and allows the lever, the bushing, and the suspension arm to release from the vehicle frame.