Saddle Vehicle Mirror Housing Downforce Design
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Solution Overview
Problem
Saddle-type vehicles face challenges in generating sufficient downforce due to the placement of mirror stays near the axle shaft, leading to instability and reduced steering performance, as elongating these stays compromises visibility and design.
Innovation Solution
The design features a rearview mirror with a stay extending outward in the vehicle width direction, a housing with an upper wall shorter than the lower wall in the front-rear direction, a concave upper surface, and protruding portions to prevent wing tip vortices, allowing for efficient downforce generation and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If mirror stays are elongated outward in vehicle width direction to produce larger down force, then down force is improved, but visibility from rider deteriorates
Solution Approach 1:
The patent transitions from elongating mirror stays in the vehicle width direction to positioning the housing in the front-rear direction. The housing is arranged to extend in the front-rear direction with its outer surface facing the rear, utilizing the front-rear dimension instead of the width dimension to generate down force while maintaining rider visibility.
Solution Approach 2:
The housing acts as an intermediary structure between the mirror body and the vehicle body. It is connected to the vehicle body via a stay and positioned to generate down force through its aerodynamic shape, while the mirror body remains visible to the rider. The housing serves as a mediator that produces down force without compromising the mirror's visibility function.
2Device complexity
If mirror stays are positioned near axle shaft to simplify structure, then device complexity is reduced, but down force effectiveness deteriorates
Solution Approach 1:
The patent uses the housing structure as a copy or adaptation of the mirror assembly that serves a dual purpose. The housing, which already exists as part of the mirror assembly, is configured to generate down force, effectively copying the functional need for down force generation without requiring separate dedicated components.
Solution Approach 2:
The housing is designed to perform multiple functions: it protects the mirror body, houses the mirror mechanism, and generates down force through its aerodynamic shape. This multi-functionality eliminates the need for separate down force generation components, maintaining structural simplicity while improving down force effectiveness.
3Force
If housing upper wall is made shorter than lower wall to generate down force, then down force is improved, but housing volume is reduced
Solution Approach 1:
The patent changes the geometric parameters of the housing by making the upper wall shorter than the lower wall in the front-rear direction. This parameter change creates an aerodynamic shape that generates down force through differential pressure distribution, accepting reduced volume as a trade-off for improved aerodynamic performance.
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 configuration enables stable downforce production on the outer sides of the vehicle, improving road surface follow-up and reducing wing tip vortex losses, resulting in enhanced stability and efficiency during travel.
Implementation Method 1
the traveling wind (air) flowing a long distance along the lower outer surface portion flows fast, while the traveling wind (air) flowing a short distance along the upper outer surface portion flows slow, and hence a pressure applied to the upper outer surface portion becomes larger than a pressure applied to the lower outer surface portion
Data Source
AI summary
A saddle-type vehicle is equipped with a rearview mirror. The rearview mirror includes a stay extending from a vehicle body outward in a vehicle width direction, and a housing connected to an extending end portion of the stay and extending outward in the vehicle width direction, the housing including a mirror body. The housing further includes an upper wall and a lower wall which are arranged at positions overlapping each other in the vertical direction of the vehicle body. The upper wall has an upper outer surface portion whose length in a front-rear direction is shorter than the length of a lower outer surface portion of the lower wall in the front-rear direction, as viewed in a cross-sectional view perpendicular to the vehicle width direction.