Vehicle Mirror Airflow Deflector for Noise and Drag Reduction

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Solution Overview

Problem

Conventional wind deflector technologies for reducing wind noise at side view mirrors increase vehicle traveling resistance by diverting wind flow, leading to turbulence and increased drag, as they either divert wind too sharply or disrupt the airflow along the vehicle body surface.

Innovation Solution

A vehicle boundary layer air flow control structure featuring an air flow deflector with a downward guiding surface on the vehicle body, dividing the airflow into inner and outer streams to divert them underneath and inward of the side view mirror, respectively, maintaining laminar flow and reducing dynamic pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a wind deflector is provided to divert traveling wind away from the side view mirror, then wind noise is reduced, but traveling resistance increases due to sharp deflection angles creating turbulence

Engineering Contradiction:
Improvewind noiseVSAvoidtraveling resistance
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The wind deflector is divided into multiple surfaces (first surface, second surface, third surface) that sequentially guide the air flow in stages rather than making a single sharp deflection. This segmented approach divides the 90-degree deflection into multiple smaller angle changes, reducing turbulence and dynamic pressure while still achieving the goal of diverting wind away from the side view mirror.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wind deflector uses curved surfaces instead of sharp edges to guide air flow. The first surface has a first curvature radius, the second surface has a second curvature radius, and the third surface has a third curvature radius, allowing smooth transitions in air flow direction. This curvature reduces turbulence and maintains lower traveling resistance while effectively diverting the air flow away from the side view mirror.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If wind deflector surfaces are made closer to the side view mirror to better control airflow, then wind noise reduction improves, but the risk of airflow collision with the mirror increases

Engineering Contradiction:
Improvewind noiseVSAvoidairflow control effectiveness
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

Different surfaces of the wind deflector have different geometric properties tailored to their specific functions. The first surface has a specific curvature radius optimized for initial deflection, the second surface has a different curvature radius for intermediate guidance, and the third surface has yet another curvature radius for final positioning. This local optimization ensures each surface performs its specific airflow control function effectively while maintaining overall system reliability.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If the wind deflector creates a transverse air flow by deflecting wind 90 degrees, then air flow crossing in front of the side view mirror is achieved, but dynamic pressure increases significantly

Engineering Contradiction:
Improveair flow collisionVSAvoiddynamic pressure
Core Design Contradiction:
Object-affected harmful factorsVSStress or pressure

Solution Approach 1:

The wind deflector is designed with dynamic airflow considerations, using curved surfaces that adapt to the natural flow patterns. The multiple surfaces with different curvature radii create a progressive deflection that dynamically guides the air flow around the side view mirror area, reducing the abrupt pressure changes associated with sharp 90-degree deflections while still achieving effective air flow separation.

Inventive Principle:
Principle #15Dynamics

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 effectively reduces wind noise and traveling resistance by ensuring airflow remains laminar, preventing turbulence and collision with the side view mirror, while maintaining airflow along the vehicle body surface.

Implementation Method 1

The downward air flow guiding surface extends in an air flow direction of the air flow with respect to the side view mirror to divert the air flow underneath the side view mirror

Methodology Applied
Scientific EffectLaminar flow: Laminar Flow

Implementation Method 2

a vehicle boundary layer air flow control structure that favorably control an air flow oriented toward an exterior door mirror

Methodology Applied
Scientific EffectBoundary layer: Boundary Layer

Data Source

PatentEP2456655B1Vehicle boundary layer air flow control structure
Publication Date: 2016.03.09 NISSAN MOTOR CO LTD
  • EP2456655B1 patent drawingFigure 1
  • EP2456655B1 patent drawingFigure 2
  • EP2456655B1 patent drawingFigure 3

AI summary

A vehicle boundary layer air flow control structure is provided with a vehicle body and a side view mirror (9). The vehicle body includes an exterior contoured surface with an air flow deflector (11). The side view mirror (9) is attached to the vehicle body to provide a diagonally rearward direction to be viewed from a driver's seat. The air flow deflector (11) has a downward air flow guiding surface (11c) provided in a vehicle body region of the exterior contoured surface of the vehicle body along which an air flow heading toward the side view mirror (9) passes. The downward air flow guiding surface extends in an air flow direction of the air flow with respect to the side view mirror (9) to divert the air flow underneath the side view mirror (9).