Rear Diffuser Movable Upper Wall for Drag Downforce Trade-off
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Solution Overview
Problem
Rear diffusers in motor vehicles typically increase drag, which is undesirable at high speeds, while also providing downforce that may not be needed in all driving conditions, affecting fuel consumption.
Innovation Solution
A rear diffuser design with a movable upper wall section connected by a hinge-type region, allowing the diffuser to switch between a high-downforce and low-drag configuration, utilizing a laminar element and spoiler lip for optimal airflow, and adjustable via an actuator for adaptive operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a rear diffuser is designed to provide high downforce, then cornering speeds and vehicle stability are improved, but drag increases which reduces fuel consumption and high-speed performance
Solution Approach 1:
The patent applies the dynamics principle by making the upper wall of the diffuser movable rather than fixed. The upper wall can be adjusted between different positions to change the diffuser angle, allowing the vehicle to optimize between downforce and drag based on driving conditions. This is achieved through a hinge mechanism that enables the upper wall to pivot relative to the vehicle body, transforming a static aerodynamic component into a dynamic one that adapts to varying operational requirements.
2Loss of energy
If a rear diffuser is made adjustable to reduce drag at high speeds, then fuel consumption improves, but the complexity of the device increases
Solution Approach 1:
The patent applies segmentation by dividing the diffuser into distinct functional zones: a fixed lower section and a movable upper wall section. This segmentation allows the upper wall to be independently adjusted while the lower section remains stationary, providing aerodynamic adjustability without requiring the entire diffuser structure to be complex and movable. The hinge mechanism connects these segments, enabling selective adjustment of only the critical upper portion.
3Loss of energy
If a foldable rear diffuser is designed with a hinge, then drag reduction is possible, but the air flow does not follow the angled folding surface well reducing the effectiveness
Solution Approach 1:
The patent applies curvature principles by designing the upper wall with a laminar flow surface that features smooth, continuous curves rather than sharp angles or abrupt transitions. This curved surface geometry guides the air flow smoothly along the diffuser, preventing flow separation and turbulence that would occur with angular folding surfaces. The laminar flow design ensures that air follows the surface contour effectively, maintaining reliable flow control while enabling drag reduction.
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
Enables improved downforce when needed and reduced drag at high speeds, optimizing fuel efficiency and performance across various driving conditions.
Implementation Method 1
the second region is coupled in a movable manner to the first region by means of at least one hinge-type region
Implementation Method 2
form an air duct whose cross section widens upward counter to the direction of travel of the motor vehicle, in order to assign more cross-sectional area to the air flow through the air duct, reducing the air velocity in the air duct and thus generating a vacuum in the region of the underbody
Implementation Method 3
the second region extends toward the rear end, that is to say the rear end of the body, of the motor vehicle and has at least one laminar element
Data Source
AI summary
A rear diffuser on the underbody of a motor vehicle having an air duct which extends at the rear of the motor vehicle counter to the longitudinal direction of the vehicle toward the rear end of the motor vehicle. The air duct has at least one upper wall, which delimits the air duct in the upward direction. The upper wall has a first region, which is coupled in a nonadjustable manner to the motor vehicle and/or to the underbody. The upper wall has a second region, which can be moved relative to the motor vehicle and/or to the underbody. The second region is coupled in a movable manner to the first region by at least one hinge-type region.