Motorcycle Side-Cowl Airflow Guide for Larger Oil Coolers

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Solution Overview

Problem

Existing straddled vehicles face challenges in increasing the volume of heat exchangers while maintaining or improving cooling efficiency, as the space required for airflow paths and guide plates restricts the radiator's dimensions.

Innovation Solution

A straddled vehicle design featuring a guide member extending outward and forward from the side cowl, forming a duct with an airflow discharge port, which facilitates smooth airflow and reduces pressure, allowing for increased volume and improved cooling efficiency without occupying additional space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a guide plate is arranged inside the side cowl to form a flow path for accelerating air, then cooling efficiency is improved, but the volume of the heat exchanger is restricted

Engineering Contradiction:
Improvecooling efficiencyVSAvoidheat exchanger volume
Core Design Contradiction:
ProductivityVSVolume of stationary object

Solution Approach 1:

The guide member is positioned outside the side cowl rather than inside, utilizing the external space dimension. This relocates the airflow acceleration function from the internal space (which constrained heat exchanger volume) to the external dimension, allowing the heat exchanger to occupy the full available internal space while the guide member manages airflow from the outside.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of stationary object

If the volume of the heat exchanger is increased, then cooling capacity is improved, but space for airflow paths and guide plates is reduced

Engineering Contradiction:
Improveheat exchanger volumeVSAvoidairflow path space
Core Design Contradiction:
Volume of stationary objectVSDevice complexity

Solution Approach 1:

The airflow management system is segmented into two distinct functional zones: the heat exchanger volume for heat exchange and the guide member for airflow acceleration. This segmentation allows each component to be optimized independently - the heat exchanger can be maximized in volume while the guide member handles airflow path formation externally, eliminating the space conflict.

Inventive Principle:
Principle #1Segmentation

3Volume of stationary object

If a guide member is arranged outside the side cowl, then heat exchanger volume can be increased, but airflow acceleration effect may be reduced

Engineering Contradiction:
Improveheat exchanger volumeVSAvoidairflow velocity
Core Design Contradiction:
Volume of stationary objectVSSpeed

Solution Approach 1:

The guide member externally replicates the airflow acceleration function that would otherwise require internal space. By creating an external copy of the flow path guidance function, the system achieves the same airflow velocity enhancement without compromising heat exchanger volume, as the guiding action occurs in the external dimension.

Inventive Principle:
Principle #26Copying

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 design enhances airflow discharge, increasing the amount of air through the heat exchanger, thereby expanding its volume and improving cooling efficiency, particularly suitable for in-line four-cylinder engines.

Implementation Method 1

Air flowing into the flow path 110 through the airflow intake port 101 is accelerated by flowing through the flow path 110 and is then discharged through the outlet port 104. Due to the accelerated airflow, the pressure of the air through the airflow discharge port 103 is reduced.

Methodology Applied
Scientific EffectBernoulli effect: Bernoulli Effect

Data Source

PatentEP4406819B1Straddled vehicle
Publication Date: 2025.10.29 YAMAHA MOTOR CO LTD
  • EP4406819B1 patent drawingFigure 1
  • EP4406819B1 patent drawingFigure 2
  • EP4406819B1 patent drawingFigure 3

AI summary

There is described a straddled vehicle, with which it is possible to both expand the volume of a heat exchanger arranged inside a side cowl and improve the cooling efficiency, in particular a motorcycle (1) including a side cowl (10) arranged outward of an oil cooler (30) in the vehicle width direction, and a guide member (20) arranged outward of the side cowl (10) in the vehicle width direction; the side cowl (10) including an airflow discharge port (14) located rearward relative to the oil cooler (30); the guide member (20) being arranged forward of the airflow discharge port (14); the guide member (20) including a first connecting portion (21) that is located forward of the airflow discharge port (14) and connected to the side cowl (10), and an outer side surface (20W) that extends forward and outward in the vehicle width direction from the first connecting portion (21); the airflow flowing on the outer side surface (20W) reducing the pressure at the airflow discharge port (14), facilitates the discharge of air through the airflow discharge port (14), and increases the amount of air that passes through the oil cooler (30).