Vehicle Rear Structure With Sliding Side-Member Floor Joint
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Solution Overview
Problem
In vehicles with a framework member integrally molded by casting, deformation of the framework member occurs during rear collisions due to load transmission from side members to the floor member and subsequently to the framework member, particularly in light collisions.
Innovation Solution
A vehicle rear portion structure with a side member attached to the framework member and a floor member featuring long hole portions in the front-and-rear direction, allowing the side member to move forward during collisions, reducing load transmission to the floor and framework members, and incorporating features like closed cross-sections, partitions, and flange attachments to enhance stiffness and energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the side member is fixed to the floor member to be immovable toward the vehicle front side, then the floor member maintains stiffness and structural integrity, but the framework member deforms during rear collision due to load transmission
Solution Approach 1:
The floor member is designed with a long hole portion that allows dynamic adjustment of the fastening position. During light rear collisions, the side member can move forward along the long hole portion, allowing the fastening to transition from the vehicle front side region (providing stiffness) to accommodate the collision force without transmitting it to the framework member. This dynamic capability resolves the contradiction between maintaining stiffness and preventing framework deformation.
2Object-affected harmful factors
If the floor member is fastened to the side member at the vehicle front side region, then the framework member is protected from load, but the floor member lacks sufficient stiffness under normal conditions
Solution Approach 1:
The long hole portion enables the fastening position to dynamically shift between the vehicle front side region and the vehicle rear side region. Under normal driving conditions, the fastening is positioned at the vehicle front side region, providing sufficient stiffness for the floor member. During rear collisions, the fastening can shift to the vehicle rear side region, reducing load transmission to the framework member while maintaining floor member functionality.
3Object-affected harmful factors
If the side member is allowed to move forward during collision, then the framework member deformation is suppressed, but the floor member requires a complex long hole portion structure
Solution Approach 1:
Instead of making the entire floor member complex, the invention applies the long hole portion feature locally at the specific position where the floor member fastens to the side member. This localized modification allows the side member to move forward during collision while maintaining the overall simplicity of the floor member structure. The long hole portion is precisely positioned to enable the desired movement without requiring complex mechanisms throughout the entire floor member.
Data Source
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AI summary
A vehicle rear portion structure (10) includes a framework member (20), a side member (40) and a floor member (32). The framework member (20) is integrally molded by casting and structures a rear portion of a vehicle body. The side member (40) extends in the vehicle front-and-rear direction and is attached to a rear portion of the framework member (20). The floor member (32) is provided at the vehicle upper side of the side member (40) and includes a long hole portion (38) with a length direction in the vehicle front-and-rear direction. The floor member (32) is fastened to the side member (40) by a fastening (18) that is inserted into a vehicle rear side region of the long hole portion (38).