One-Piece Cast Rear Frame for Higher EV Rear Stiffness
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Solution Overview
Problem
The existing rear frames of electric vehicles suffer from reduced stiffness due to the use of mechanical fasteners like self-piercing rivets and flow drill screws, which leads to increased impact energy absorption and reduced crashworthiness.
Innovation Solution
A rear frame designed as a unitary one-piece structure by the casting method, comprising a pair of side portions and a plurality of cross portions, which eliminates the need for mechanical fasteners and enhances structural stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical fasteners (self-piercing rivets, flow drill screws) are used to join rear side members and crossmembers, then assembly is simplified and manufacturing is easier, but stiffness of the vehicle rear structure is reduced
Solution Approach 1:
The patent merges multiple separate components (rear side members and crossmembers) into a single integrated rear frame structure. This eliminates the need for mechanical fasteners and welding joints, thereby resolving the contradiction by achieving both ease of manufacture (no assembly required) and high stiffness (continuous structure without joint weaknesses).
Solution Approach 2:
While the overall structure is integrated, the patent segments the rear frame into functional regions (side members, crossmembers, reinforcement portions) within the single-piece casting. This allows optimization of stiffness in critical areas while maintaining the benefits of a unitary structure, resolving the contradiction between manufacturing simplicity and structural strength.
2Device complexity
If multiple separate components are used in the rear frame, then manufacturing and assembly become more complex, but repair and replacement become easier
Solution Approach 1:
The patent combines multiple replaceable components into a single rear frame structure, reducing device complexity from multiple parts to one integrated component. While this makes the overall structure simpler, the modular design of the integrated frame allows for controlled replacement of the entire assembly or specific sections, balancing manufacturing simplicity with repairability.
3Ease of repair
If mechanical fasteners are used to connect rear frame components, then the structure allows for disassembly and repair, but crashworthiness and impact energy absorption are reduced
Solution Approach 1:
The patent merges separate components connected by mechanical fasteners into a single-piece cast structure. This eliminates joint weaknesses that compromise crashworthiness while maintaining reliability through the continuous, homogeneous structure. The integrated design ensures consistent material properties throughout, preventing failure at fastener locations during impact events.
Solution Approach 2:
The patent employs composite material construction within the integrated rear frame, combining different material properties in specific regions (such as reinforcement portions with higher strength requirements) to optimize both crashworthiness and controlled disassemblability for repair purposes.
Data Source
AI summary
An embodiment rear frame includes a pair of side portions spaced apart from each other in a width direction of a vehicle, each side portion having a damper receptacle in which a suspension damper is mounted, a first cross portion connecting front portions of the pair of side portions, and a second cross portion connecting rear portions of the pair of side portions, wherein the pair of side portions, the first cross portion, and the second cross portion together are a unitary one-piece structure.