Exterior Mirror Step Geometry for Fold-Joint Noise Reduction
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Solution Overview
Problem
Rear-view mirrors on motor vehicles experience noise emissions due to airflow hitting edges or protruding elements at the swivel joint, which is a design limitation in reducing noise and maintaining a compact form factor.
Innovation Solution
The observation device features a recessed area between the foot and head elements, creating a step that disrupts airflow and separates it from the mirror surface, preventing noise formation by guiding air flow along the foot element and then over the gap, thus avoiding the edge of the head element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the exterior mirror is designed with a folding mechanism to reduce space requirements and damage risk, then the overall width of the vehicle is reduced and space requirements are minimized, but airflow directed onto the gap edges generates noise and acoustic disturbances occur at the pivot joint
Solution Approach 1:
The patent introduces a step structure that creates a vertical dimension offset between the first and second housing portions. This vertical offset (in the direction perpendicular to the airflow) causes the airflow to separate from the surface at the step, preventing it from striking the edge of the head element. This dimensional change effectively redirects the airflow path without compromising the folding mechanism's space-saving benefits.
Solution Approach 2:
The patent converts the potentially harmful airflow that would otherwise strike the mirror edge and generate noise into a beneficial flow separation at the step. By strategically positioning the step, the design harnesses the airflow itself to separate cleanly, transforming what was a noise-generating interaction into a smooth flow transition that reduces acoustic disturbances.
2Volume of moving object
If the exterior mirror is designed with a folding mechanism to minimize space requirements, then the overall width for the vehicle is reduced, but the folding mechanism requires a joint and gap that allows relative movement of the mirror surface
Solution Approach 1:
The patent merges the noise reduction function with the existing folding mechanism structure by integrating the step directly into the housing design. Rather than adding a separate noise reduction component, the step is formed as part of the housing itself, combining the structural requirements of the folding mechanism with the aerodynamic requirements for noise reduction in a single integrated solution.
3Ease of manufacture
If airflow is allowed to flow directly over the gap to maintain simple structure, then the design remains simple and cost-effective, but airflow strikes the edge of the head element causing unwanted noise formation
Solution Approach 1:
The patent applies local quality by introducing the step feature specifically at the critical location where the housing portions meet and where airflow separation would naturally occur. This localized modification to the housing geometry at the gap area provides noise reduction precisely where needed, without requiring changes to the entire mirror structure, thereby maintaining overall design simplicity while addressing the noise issue.
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 design effectively reduces acoustic abnormalities by ensuring air flows smoothly over the observation device, minimizing noise emissions while maintaining a robust and cost-effective structure compatible with airflow during vehicle travel.
Implementation Method 1
The head element body has at least one recessed area adjacent to the gap, such that a step is formed between the base element body and the head element body by the recessed area. This disrupts the airflow and causes it to separate from the surface.
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to an observation device (1) for a motor vehicle for observing traffic behind it, comprising a base element (10) with a base element body (12) for attachment to a body or an add-on part of the motor vehicle, and comprising a head element (20) pivotally arranged on the base element (10) with a head element body (21) and an observation element (2) arranged therein or thereon, wherein the base element body (12) and the head element body (21) abut each other at at least one gap (40) and the head element body (21) has at least one recessed area (24) adjacent to the gap (40), such that a step (50) is formed between the base element body (12) and the head element body (21) by the recessed area (24). The invention further relates to a motor vehicle equipped with the observation device.