Aerodynamic Skirt Bottom Protrusion for Vortex Reduction

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Solution Overview

Problem

Existing aerodynamic skirts for vehicles, particularly trailers, suffer from air wrapping around the bottom edge, creating vortices that increase drag and pressure on the chassis and wheels, leading to reduced fuel efficiency and increased emissions.

Innovation Solution

Incorporating a protrusion, such as a plate, transversally arranged with respect to the panel at the bottom end of the aerodynamic skirt, which reduces the formation of vortices and minimizes airflow beneath the vehicle, thereby decreasing pressure on the chassis and wheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If aerodynamic skirts are made straight or corrugated without additional elements, then manufacturing is simple, but air wraps around the bottom edge creating vortices that increase drag

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidaerodynamic drag
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The aerodynamic skirt is divided into multiple segments along its length, with each segment capable of independent movement. This segmentation allows the skirt to adapt its shape to reduce vortex formation at the bottom edge while maintaining manufacturing simplicity through modular construction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The aerodynamic skirt incorporates dynamic elements that allow it to change shape in response to airflow conditions. The skirt can transition between different configurations to optimize aerodynamic performance and reduce drag, particularly by controlling the wraparound effect at the bottom edge.

Inventive Principle:
Principle #15Dynamics

2Productivity

If aerodynamic skirts extend downward to create smooth surfaces, then airflow is directed more efficiently, but the gap between trailer and road creates turbulence and increased drag

Engineering Contradiction:
Improvefuel efficiencyVSAvoidaerodynamic drag
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The aerodynamic skirt uses dynamic positioning mechanisms to adjust its height and angle, optimizing the seal between the trailer and road surface. This dynamic adjustment reduces the gap-induced turbulence and improves airflow efficiency, leading to better fuel economy.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The aerodynamic skirt modifies key parameters such as its length, angle, and position relative to the road surface to minimize the gap effect. By changing these parameters, the skirt effectively reduces turbulence and drag while maintaining efficient airflow direction.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If protrusions are added to the bottom end of aerodynamic skirts to reduce vortices, then drag is reduced and fuel efficiency improves, but device complexity increases

Engineering Contradiction:
Improveaerodynamic dragVSAvoidskirt structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The protrusion element is implemented as a separate, modular component that can be attached to the aerodynamic skirt segments. This segmentation allows for easier manufacturing and installation while achieving the vortex-reducing effect. The modular design minimizes the increase in overall device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protrusion acts as an intermediary element between the aerodynamic skirt and the airflow, specifically targeting the vortex formation at the bottom edge. This focused intervention reduces drag without requiring complete redesign of the entire skirt structure, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 protrusion effectively reduces airflow under the vehicle, enhancing fuel efficiency and reducing drag, resulting in improved fuel economy and lower emissions.

Implementation Method 1

air tends to wrap around the bottom edge of the aerodynamic skirt, which increases the amount of air that flows under the vehicle and adds pressure to the vehicle chassis and wheels. The effect is similar to the situation at a wingtip of a plane, which creates a vortex of flowing air.

Methodology Applied
Scientific EffectVortex: Vortex Ring

Implementation Method 2

aerodynamic skirts help to decrease the drag force acting on the vehicle. The protrusion reduces the vortex and, thus, reduces the amount of air flowing beneath the panel's bottom end and under the vehicle. This reduces the pressure against the chassis and the wheels and, thus, reduces the vehicle's overall resistance to airflow.

Methodology Applied
Scientific EffectAerodynamic drag: Drag

Data Source

PatentEP4640534A1Aerodynamic skirt and vehicle
Publication Date: 2025.10.29 ZF CV SYST EURO BV
  • EP4640534A1 patent drawingFigure 1~2
  • EP4640534A1 patent drawingFigure 3~4
  • EP4640534A1 patent drawingFigure 5~6

AI summary

The disclosure relates to an aerodynamic skirt (12) for a vehicle (10), in particular for a trailer (18) or a tractor-trailer-combination (14). The aerodynamic skirt (12) comprises a mounting orientation (28) defining an orientation (30) of the aerodynamic skirt (12) with respect to a driving direction (26) of the vehicle (10). The aerodynamic skirt (12) comprises a panel (32), which is arranged at least essentially vertically when the aerodynamic skirt (12) is mounted in the mounting orientation (28). The panel (32) comprises a bottom end (34) with respect to the mounting orientation (28). The aerodynamic skirt (12) comprises a protrusion (36) at the bottom end (34) of the aerodynamic skirt (12). The protrusion (36) is arranged transversally with respect to the panel (32).