Vehicle Roof Ditch Welding for Multi-Layer Steel Crash Performance
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Solution Overview
Problem
Current vehicle roof structures face challenges in ensuring weld strength with multiple layers of steel, particularly with press hardened steel, where trimming sheets is necessary for quality welds, which can compromise crash performance.
Innovation Solution
The implementation of a vehicle roof structure with a roof ditch that accommodates separate structural and attachment welds, allowing multiple sheets of material without trimming any components, and utilizing three-metal thickness welds between specific overlapping end portions for enhanced reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple sheets of steel are applied in the roof ditch area for crash regulations, then crash performance is improved, but weld strength cannot be guaranteed through four sheets or thicker
Solution Approach 1:
The patent divides the welding operation into two separate rows: a first row of welds joining the side panel to the stiffener and inner panel, and a second row of welds joining the roof panel to the side panel and inner panel. This segmentation allows each weld row to operate independently, ensuring that weld strength is not compromised by the presence of multiple steel sheets (four to seven layers) in the roof ditch area, while still maintaining the required crash performance through the combined structural integrity of both weld rows.
2Reliability
If press hardened steel is trimmed back to enable quality welds, then weld strength is improved, but crash performance is reduced
Solution Approach 1:
The patent implements two separate rows of welds positioned at different locations in the roof ditch area. The first row joins the side panel to the stiffener and inner panel, while the second row joins the roof panel to the side panel and inner panel. This segmentation eliminates the need to trim press hardened steel back, as each weld row can be positioned to avoid interference from adjacent sheets, thereby maintaining both weld strength and crash performance without material removal.
Solution Approach 2:
The patent utilizes the vertical dimension within the roof ditch area to position two distinct rows of welds at different depths. This dimensional approach allows welds to be made through multiple sheets (four to seven layers) without requiring trimming, as the welds are distributed across different vertical positions rather than attempting to weld through all layers at a single location.
3Device complexity
If one row of welds is used to attach all components, then device complexity is reduced, but the ability to maintain both weld strength and crash performance is compromised
Solution Approach 1:
The patent employs two separate rows of welds instead of a single row to join the roof panel, side panel, stiffener, and inner panel. This segmentation allows each weld row to focus on specific component connections, ensuring that weld strength requirements are met for each joint while accommodating the presence of multiple steel sheets (four to seven layers) in the roof ditch area, thereby maintaining both reliability and manageable complexity.
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 solution enables multiple sheets of steel to be applied in the roof ditch area for crash regulations without trimming, ensuring robust weld strength and maintaining crash performance by separating welds into distinct sections for improved structural integrity.
Implementation Method 1
structural welds associated only with the vehicle body and separate attachment welds only connecting the vehicle roof to the vehicle body are provided on the bottom of the roof ditch
Data Source
AI summary
A vehicle roof structure includes a vehicle body and a vehicle roof. The vehicle body includes an outer side panel, a body stiffener and an inner side panel. The vehicle roof includes a roof panel and a roof stiffener. A connection portion between the vehicle body and vehicle roof forms a roof ditch which extends along a longitudinal direction of the vehicle roof structure. The roof ditch includes a bottom which extends laterally between the vehicle body and vehicle roof. Structural welds associated only with the vehicle body and separate attachment welds only connecting the vehicle roof to the vehicle body are provided on the bottom of the roof ditch. The two welds allow multiple sheets of material to be applied in the roof ditch for crash regulations.