Active Crash Structure with Release Connector
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Solution Overview
Problem
Current active crash structures in motor vehicles do not effectively manage energy absorption during crashes, leading to high acceleration forces on occupants, which can result in severe injuries, as they lack a controlled mechanism to initiate deformation only under specific crash conditions.
Innovation Solution
An active crash structure arrangement featuring a primary and secondary structure interconnected by a fixed and a releasable connector, where the secondary structure includes a predefined deformation zone that deforms only upon actuation of the releasable connector upon receiving a crash signal, utilizing a pyrotechnic charge to release the connection and absorb crash forces beyond a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the vehicle structure is made rigid to improve driving dynamics, then the acceleration forces on occupants increase during crashes, but if the structure is made deformable to absorb energy, then the driving dynamics deteriorate
Solution Approach 1:
The connector system transitions from a static rigid connection to a dynamic system that can change its mechanical properties based on crash conditions. The shear bolt acts as a mechanical fuse that transitions the connection from rigid to deformable upon exceeding a threshold force, allowing the structure to adapt its stiffness dynamically during impact events
Solution Approach 2:
The system changes the mechanical parameter of structural stiffness from a fixed high value during normal operation to a controlled lower value during crashes. The predefined deformation zone is designed with specific geometric parameters (reduced thickness) that trigger plastic deformation at a predetermined force threshold, thereby changing the energy absorption characteristics of the structure
2Loss of energy
If a releasable connector is used to improve energy absorption, then the connection reliability during normal operation decreases, but structural integrity is compromised without a fixed connector
Solution Approach 1:
The connection system is segmented into two independent connectors with different functions: a fixed connector (first connector) that ensures permanent structural integrity and a releasable connector (second connector with shear bolt) that provides controlled energy absorption. This segmentation allows each connector to specialize in its specific function without compromising the other
Solution Approach 2:
The shear bolt acts as an intermediary element between the rigid connection and the deformable zone. It serves as a mechanical fuse that remains intact during normal operation to maintain connection reliability, but fails in a controlled manner during crashes to initiate energy absorption in the predefined deformation zone
3Loss of energy
If the deformation zone is made more compliant to improve energy absorption, then the structural strength decreases, but safety is compromised without controlled deformation timing
Solution Approach 1:
The deformation zone is pre-configured with specific geometric features (reduced thickness regions) during manufacturing to create predetermined weak points. These preliminary structural modifications ensure that when a crash occurs, deformation initiates at the predefined locations rather than randomly throughout the structure, controlling both the timing and location of energy absorption
Solution Approach 2:
The deformation zone incorporates localized regions of reduced thickness (e.g., 5-10mm thick sections in a otherwise 20-30mm thick structure) that create specific areas of mechanical weakness. This local quality change allows the structure to maintain overall strength while providing controlled deformation paths at specific locations during impact
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
This solution allows for controlled deformation of the secondary structure during crashes, reducing occupant acceleration and enhancing energy absorption, thereby minimizing injury risk while maintaining structural integrity during normal driving conditions.
Implementation Method 1
the second connector comprises a pyrotechnic charge and is configured to release its connection between the primary and secondary structures upon ignition of the pyrotechnic charge
Implementation Method 2
the deformation zone of the secondary structure being configured to deform upon the application of a crash force to the secondary structure after actuation of the second connector
Data Source
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AI summary
There is disclosed an active crash structure arrangement for a motor vehicle, the arrangement having a primary structure (2) and a secondary structure (3), said structures being interconnected by i) a first connector (20) which fixedly interconnects said primary and secondary structures (2, 3), and also initially by ii) a second connector (21) which releasably interconnects said primary and secondary structures (2, 3). The first and second connectors (20, 21) are spaced apart from one another, and the secondary structure (3) includes a predefined deformation region (15) located between the first and second connectors (20, 21). The second connector (22) is actuable upon receipt of a release signal to release its connection between the primary and secondary structures (2, 3), and the deformation region (15) of the secondary structure (3) is configured to deform upon the application of a crash force to the secondary structure (3) after actuation of the second connector (21).