Vehicle Floor Longitudinal Beam Hollow Structure
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Solution Overview
Problem
Conventional vehicle body structures in the floor region of passenger compartments are aerodynamically unfavorable, heavy, and lack the necessary stiffness and crash safety, particularly when using light metals like aluminum, due to differences in joining technology and material distribution compared to steel constructions.
Innovation Solution
A continuous longitudinal beam extending from the front to the rear of the vehicle is formed as a closed hollow beam with a stepped edge on the bottom and an angled profile on top, using hot-formed steel for the closure part and aluminum for the floor panel, connected via high-strength rivets and resistance spot welding, allowing for tailored stiffness and weight-saving design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional longitudinal beam with hat profile is used, then the structure is easy to manufacture, but the underbody structure becomes jagged and aerodynamically unfavorable
Solution Approach 1:
The longitudinal beam is merged with the floor panel to form an integrated closed hollow beam structure. The floor panel forms the bottom wall and part of the side wall, while the closure part forms the top wall, creating a unified aerodynamic underbody surface that eliminates the jagged appearance of separate hat profile beams.
Solution Approach 2:
The longitudinal beam uses a composite construction with the floor panel (aluminum or steel) and the closure part (hot-formed steel) joined together. This composite structure allows optimization of each component for its specific function while achieving overall aerodynamic efficiency and structural integrity.
2Weight of moving object
If light metal materials like aluminum are used, then weight is reduced, but joining technology becomes more complex and crash safety may be compromised
Solution Approach 1:
The invention uses a composite material system combining aluminum floor panel with hot-formed steel closure part. The steel closure part provides high strength for crash protection in the critical longitudinal beam region, while the aluminum floor panel reduces overall weight. This material mix optimizes both weight reduction and crash safety by placing stronger materials where needed.
Solution Approach 2:
Different regions of the vehicle body use different materials according to their specific requirements. The longitudinal beam closure part uses hot-formed steel for high strength and crash protection, while the floor panel can use lightweight aluminum. This local differentiation of material properties allows optimization of both weight and safety.
3Strength
If the longitudinal beam is made from steel only, then stiffness and crash safety are ensured, but weight cannot be optimized
Solution Approach 1:
The longitudinal beam employs a composite construction where the floor panel (aluminum or steel) and closure part (hot-formed steel) work together to provide the required stiffness. The closed hollow beam geometry with aluminum flooring reduces weight while the steel closure part maintains structural strength and stiffness for crash protection.
4Strength
If elaborate welding techniques like laser beam welding are used for aluminum-steel connection, then connection strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
A corrosion-resistant intermediate layer (such as a protective coating or intermediate material) is introduced between the aluminum floor panel and steel closure part. This intermediate layer facilitates the connection between dissimilar metals, allowing for simpler joining processes while maintaining connection strength and preventing direct corrosion.
Solution Approach 2:
The invention replaces complex elaborate welding techniques (laser beam welding, inert gas welding) with simpler mechanical joining methods such as high-strength solid punch rivets. This substitution maintains adequate connection strength for the longitudinal beam while significantly reducing manufacturing complexity and cost for mass production.
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 configuration results in a lightweight, stable, and crash-safe vehicle body structure with improved aerodynamics and cost-effective manufacturing, achieving high stiffness and crash protection while minimizing material usage and corrosion risks.
Implementation Method 1
the longitudinal beam closure part is formed as longitudinal beam steel closure part from hot-formed steel
Implementation Method 2
a riveted joint which is cost-saving and well suited for large series production is proposed for the connection of the floor aluminum plate and the longitudinal beam steel closure part
Implementation Method 3
they can be easily connected at lap joint with a border flange by welding, preferably resistance spot welding
Data Source
AI summary
The invention relates to a vehicle body structure in the floor region of the occupant compartment having on both sides a respective longitudinal beam (3) in the floor region of the occupant compartment between a transmission tunnel and a side sill. According to the invention each longitudinal beam (3) extends longitudinally continuously over the entire footwell length from the front end (4) to a heel plate. The longitudinal beam (3) is here formed on the bottom side as a closed longitudinal hollow beam by virtue of a longitudinal beam stepped edge (9) of the floor panel (10AB) and on the top side as a longitudinal beam closure part (11SW) by virtue of a longitudinal beam angle section connected to the top side.