Vehicle Lower Section Torque Box Bulkhead Design
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Solution Overview
Problem
Existing vehicle lower section structures fail to effectively suppress plastic deformation of the torque box during small overlap collisions, particularly when load is input from the front wheel, leading to potential intrusion into the vehicle cabin.
Innovation Solution
A vehicle lower section structure incorporating a bulkhead that forms a closed cross-section profile with the floor panel and front side member, positioned to oppose the front wheel, enhancing the structure's strength and rigidity by dispersing collision loads through a dash cross member into the floor panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the torque box is sectioned by a reinforcement member, then the structural strength is improved, but the complexity of the structure increases
Solution Approach 1:
The torque box is divided into multiple sections by introducing a bulkhead that runs along the vehicle body front-rear direction inside the torque box, sectioning the inside of the torque box in the vehicle width direction. This segmentation increases strength without requiring complex external reinforcement members.
Solution Approach 2:
The bulkhead is integrated with the torque box structure, and the dash cross member is joined to the upper face of the floor panel overlapping with the bulkhead, forming a unified structural system that distributes collision loads efficiently through the closed cross-section profile.
2Strength
If the torque box is made more rigid to suppress plastic deformation, then the resistance to collision load is improved, but the weight of the structure increases
Solution Approach 1:
The torque box is segmented by the bulkhead into multiple compartments, which increases rigidity and resistance to collision load without requiring additional heavy reinforcement materials. The segmentation allows the structure to better distribute and resist applied forces.
Solution Approach 2:
The structure utilizes a composite configuration combining the torque box, bulkhead, floor panel, and dash cross member to form a closed cross-section profile that efficiently distributes collision loads, achieving high rigidity without excessive weight addition.
3Strength
If the bulkhead is positioned to oppose the front wheel, then the suppression of plastic deformation is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The bulkhead is pre-positioned inside the torque box to oppose the front wheel during collision, and the dash cross member is pre-joined to the upper face of the floor panel overlapping with the bulkhead. This preliminary configuration ensures that when collision load is applied, the structure is already optimized to distribute the force through the closed cross-section profile, reducing the need for extremely precise manufacturing tolerances.
Data Source
AI summary
A vehicle lower section structure that includes: a floor panel; a dash panel partitioning an engine compartment from a vehicle cabin; a front side member that extends in a vehicle body front-rear direction on a vehicle body front side of the dash panel, and that is disposed along a lower face of the floor panel on a vehicle body rear side of the dash panel; a rocker extending in the vehicle body front-rear direction; a torque box that extends in the vehicle width direction, that is joined to the lower face of the floor panel between the front side member and the rocker in bottom face view, and that forms a closed cross-section profile together with the floor panel; and a bulkhead running along the vehicle body front-rear direction inside the torque box and sectioning the inside of the torque box in the vehicle width direction.