EV Rear Rail Structure for Progressive Crash Energy Absorption
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Solution Overview
Problem
Current rear rail designs for electric vehicles face limitations in energy absorption during high-energy rear collisions, leading to potential safety risks for occupants due to the transmission of kinetic energy to the vehicle body and occupants.
Innovation Solution
The rear rail design optimizes energy absorption by incorporating a transition zone with a specific material composition and geometry, allowing for both controlled buckling and double bending deformation, ensuring the transition zone takes over energy absorption after the rear portion is fully deformed, with a material having a fracture strain of at least 0.6 and a critical bending angle of at least 75°, and utilizing high-strength materials like press-hardened or cold-stamped steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rear rail design uses controlled buckling for energy absorption, then energy absorption capacity is improved, but remaining crash energy is transmitted to the vehicle body and occupants
Solution Approach 1:
The rear rail is segmented into three distinct zones: rear portion, transition zone, and front portion. Each zone has specific geometric characteristics and material properties optimized for its function. The rear portion with lower strength undergoes controlled buckling, the transition zone with intermediate properties undergoes double bending, and the front portion with higher strength provides anti-intrusion protection.
Solution Approach 2:
Different zones of the rear rail have different material properties and geometric characteristics. The rear portion uses material with lower ultimate tensile strength (700-1000 MPa) for easy buckling, while the front portion uses higher strength material (1000-1500 MPa) for protection. The transition zone uses intermediate strength material (700-1500 MPa) with specific fracture strain (≥0.6) and critical bending angle (≥75°) to enable double bending deformation.
2Loss of energy
If the transition zone and rear portion are designed for controlled deformation, then energy absorption is improved, but structural integrity may be compromised under high-energy crashes
Solution Approach 1:
The patent specifies precise parameter ranges for different zones: rear portion ultimate tensile strength (700-1000 MPa), transition zone ultimate tensile strength (700-1500 MPa) with fracture strain ≥0.6 and critical bending angle ≥75°, front portion ultimate tensile strength (1000-1500 MPa). These parameter changes enable controlled deformation while maintaining structural integrity.
Solution Approach 2:
The rear rail employs a composite structure with different material grades in different zones. The transition zone uses material with intermediate properties between the rear and front portions, creating a gradient structure that facilitates progressive deformation from rear to front while maintaining overall structural integrity.
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 design effectively absorbs crash energy through controlled buckling and double bending, enhancing passenger safety and preventing intrusion into critical vehicle spaces, such as the battery pack, while maintaining structural stability and controlling deformation sequences during collisions.
Implementation Method 1
the transition zone is made from a material having a fracture strain of at least 0.6 and a critical bending angle of at least 75°
Implementation Method 2
it is possible to absorb energy during a rear collision not only through the controlled buckling deformation of the rear section but also through the double bending deformation of the transition zone in its upper and lower bends
Implementation Method 3
the rear portion absorbs energy during a rear collision, through controlled buckling for example
Data Source
AI summary
Rear structure for an electric vehicle having a rear rail which includes a rear portion, a front portion and a transition zone, such that in the event of a rear crash the rear portion and the transition zone are both able to deform to maximize the amount of energy absorption.