Roof Rack Crossbar Profile for Airflow Separation and Noise Control
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Solution Overview
Problem
Existing roof rack crossbar designs fail to effectively manage airflow and noise at strong positive incidence angles, leading to undesirable noise effects when interacting with the vehicle roof and its surroundings, particularly at the front roof rack area.
Innovation Solution
A crossbar carrier profile with a rounded front part and a trailing part featuring a diagonally sloping flat leading surface followed by a rounded tear-off projection, where the tear-off edge is positioned within specific intervals and has a minimum radius, creating a sharp or rounded edge to divert airflow and suppress noise oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple square or rectangular profile is used, then manufacturing is easier, but airflow management and noise reduction are insufficient
Solution Approach 1:
The patent applies curvature to the profile by implementing a rounded front part and a rounded rear part instead of sharp corners. This curvilinear design guides airflow smoothly around the crossbar, preventing turbulent flow and noise generation while maintaining manufacturing feasibility through standard extrusion processes.
Solution Approach 2:
The patent applies different geometric characteristics to different parts of the profile: a rounded front part for airflow guidance, a diagonally sloping flat leading surface in the bottom area for specific flow control, and a rounded rear part for smooth flow separation. This localized optimization addresses noise issues without complicating overall manufacturing.
2Object-affected harmful factors
If aerodynamic shapes like wings are used, then airflow is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses rounded front and rear parts with simple curvilinear geometry rather than complex wing-shaped aerodynamic profiles. This provides sufficient airflow management through smooth flow guidance while maintaining a simple extrudable cross-section that is easy to manufacture.
Solution Approach 2:
The patent introduces a diagonally sloping flat leading surface specifically in the bottom area of the front part, combining simple geometric elements with localized functional optimization to achieve good airflow characteristics without overall profile complexity.
3Adaptability or versatility
If the crossbar is positioned at strong positive incidence angles, then mounting flexibility is improved, but noise oscillations increase
Solution Approach 1:
The rounded front and rear parts of the profile create smooth airflow guidance that remains effective across a range of incidence angles. The curvilinear shape prevents flow separation and turbulent oscillations even when the crossbar is mounted at strong positive angles, reducing noise while maintaining mounting flexibility.
Solution Approach 2:
The diagonally sloping flat leading surface in the bottom area specifically addresses airflow at incidence angles by guiding flow smoothly over the bottom surface, preventing turbulent oscillations and noise while allowing flexible mounting positions.
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
The solution effectively suppresses noise manifestations by diverting airflow and preventing oscillations across the entire crossbar carrier profile width, ensuring quiet operation even at dense airflow conditions.
Implementation Method 1
the bottom area of the front part has a flat leading surface running diagonally downwards, whereas said flat leading surface is followed by a rounded tear-off projection terminating along its entire length by a tear-off edge
Data Source
Figure 1~3
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Figure 6~7
AI summary
Profile of the crossbar carrier, in particular for mounting to the roof rails of vehicles, consisting of a formed solid body (1), the outer profile of which has a rounded front part (2) and a trailing part (3) at the rear end, provided that the bottom area of the front part (2) has a flat leading surface (21) running diagonally downwards, followed by a rounded tear-off projection (22) terminating along its entire length by a tear-off edge (221), which is located in an area defined by the first interval of 0.31ps to 0.73ps measured perpendicularly from the determining line (a) and the second interval of 0,75pk to 0.98pk, where the determining line (a) is the line between the furthest point (B) of the front part (2) and the furthest point (A) of the outflow part (3) of the body (1), (ps) is the first determining parameter, based on the diameter of the third circle (k3) inscribed at the point of the greatest width of the encircled cross-sectional profile of the body (1), and (pk) is the second determining parameter, based on the diameter of the second circle (k2) corresponding to the linear distance between points (A) and (B).