Lower Vehicle-Body Cross Member Reinforcement for Battery Protection
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Solution Overview
Problem
In vehicles with battery units positioned below the floor panel, stress concentration at the joint of the cross member and side sill during a side collision leads to improper crushing of the floor tunnel, potentially causing the vehicle body to hit the battery units or the units to collide with each other.
Innovation Solution
A reinforcement portion is added to the cross member to reinforce the ridgelines, excluding the central position, which suppresses sectional deformation and improves vehicle-body rigidity, preventing the vehicle body from hitting the battery units and reducing collisions between them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of ridgelines of the cross member is increased to improve load transmission in side collision, then the load transmission capability is improved, but stress concentration is generated at the joint portion of the cross member and side sill, causing the floor tunnel to not crush properly and the floor panel to be crushed largely
Solution Approach 1:
The patent applies local quality by providing a reinforcement portion only at specific locations (both end portions in the vehicle width direction) of the cross member, rather than uniformly reinforcing the entire structure. This localized reinforcement strengthens the joint portions with side sills to prevent stress concentration and battery unit damage, while allowing the central portion to maintain its ability to crush and absorb collision energy.
2Stability of the object's composition
If the number of ridgelines is increased to suppress floor panel vibrations, then the vehicle-body rigidity is improved, but the floor tunnel crushing is suppressed and battery unit protection is compromised
Solution Approach 1:
The reinforcement portions are strategically placed only at the end portions of the cross member in the vehicle width direction, creating local quality differences. This allows the cross member to maintain high rigidity at the joint portions for vibration suppression, while the central portion remains capable of controlled crushing to protect battery units during side collisions.
3Strength
If the cross member is reinforced to prevent sectional deformation, then the load transmission is maintained, but the floor tunnel cannot crush properly during side collision
Solution Approach 1:
The patent implements local quality by differentiating the reinforcement distribution: the end portions of the cross member receive reinforcement to suppress sectional deformation and maintain load transmission, while the central portion remains unreinforced to allow controlled crushing and energy absorption during side collisions, thereby protecting the battery unit.
Data Source
AI summary
A floor tunnel protruding upwardly and extending in a vehicle longitudinal direction at a central position, in a vehicle width direction, of a floor panel, a cross member having ridgelines extending in the vehicle width direction at a rear end of the floor tunnel and a closed-cross section portion interconnecting a pair of right-and-left side sills, and a pair of right-and-left battery units positioned below the floor panel and between the side sills and provided on right-and-left sides, in the vehicle width direction, of the floor tunnel are provided. The cross member is provided with a reinforcement portion to reinforce the ridgelines in a range, in the vehicle width direction, which includes at least the position of the battery units and excludes the central position, in the vehicle width direction, of the floor panel.