Motorcycle Outer Air Guide Layout for Radiator Cooling Airflow

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Solution Overview

Problem

Straddled vehicles, such as motorcycles, experience reduced cooling efficiency and increased air resistance due to air flows interacting with radiator hoses and oil coolers, leading to disturbed wind flow and reduced cooling performance.

Innovation Solution

The implementation of an outer air guide that overlaps with both the engine and cooling devices, covering most of the hoses and guiding travel wind to prevent inward air flows, with a burble point design that directs wind rearward and outward, reducing air resistance and enhancing cooling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the rear edge portion of the lower portion of the side cover extends inward in the vehicle width direction, then the side cover can cover more of the engine area, but air flow is generated flowing inward from the rear edge portion which contacts the radiator hose and disturbs the travel wind flow

Engineering Contradiction:
Improvecoverage area of side coverVSAvoidair resistance and cooling efficiency reduction
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

An outer air guide is introduced as an intermediary component between the side cover and the radiator hose. This air guide extends in the vehicle width direction and positions the radiator hose between itself and the side cover, preventing direct contact between inward-flowing air and the hose while maintaining the side cover's protective coverage function.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The outer air guide functions as a flexible aerodynamic shell that manages air flow paths. By extending this shell structure in the vehicle width direction, the patent creates a controlled flow environment that prevents harmful air currents from reaching the radiator hose while maintaining overall vehicle aerodynamics.

Inventive Principle:
Principle #30Flexible shells and thin films

2Device complexity

If an air flow is generated flowing inward in the vehicle width direction from the rear edge portion of the side cover, then the side cover structure is simplified, but the air flow contacts the radiator hose and reduces cooling efficiency

Engineering Contradiction:
Improveside cover structure complexityVSAvoidcooling efficiency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The outer air guide serves as a mediating structure that adds minimal complexity to the side cover assembly while effectively preventing air flow from contacting the radiator hose. This intermediary component preserves the simplicity of the original side cover design while solving the cooling efficiency problem.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of energy

If the tangent line at the burble point is obliquely inclined so that it moves away from the center of the straddled vehicle in the width direction, then travel wind is directed rearward and outward reducing air resistance, but the design complexity of the outer air guide increases

Engineering Contradiction:
Improveair resistanceVSAvoidouter air guide design complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent optimizes the geometric parameters of the outer air guide, specifically the inclination angle of the tangent line at the burble point. By adjusting this parameter to be obliquely inclined away from the vehicle center, the design achieves reduced air resistance while maintaining manufacturing feasibility and structural simplicity.

Inventive Principle:
Principle #35Parameter changes

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 effectively reduces air resistance and improves cooling efficiency by preventing air flow disturbances and ensuring efficient wind discharge from the cooling devices, thereby enhancing the overall performance of the straddled vehicle's cooling system.

Implementation Method 1

when an air flow is generated and flows inward in the vehicle width direction from the rear edge portion of the side cover, the air flow could come into contact with the radiator hose

Methodology Applied
Scientific EffectAir flow:

Implementation Method 2

When such an air flow contacts the radiator hose, the air resistance of the motorcycle increases

Methodology Applied
Scientific EffectAir resistance: Drag

Implementation Method 3

a radiator disposed in front of the engine and configured to cool liquid with travel wind

Methodology Applied
Scientific EffectHeat transfer:

Implementation Method 4

cooling liquid with travel wind

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 5

the air flow crosses and impacts with the travel wind that has passed the radiator, disturbing the flow of the travel wind that has passed the radiator

Methodology Applied
Scientific EffectFlow disturbance:

Data Source

PatentEP3348462B1Straddled vehicle
Publication Date: 2024.08.07 YAMAHA MOTOR CO LTD
  • EP3348462B1 patent drawingFigure 1
  • EP3348462B1 patent drawingFigure 2
  • EP3348462B1 patent drawingFigure 3

AI summary

A straddled vehicle includes an outer air guide 28 overlapping both an engine 14 and radiator 34 in a side view and including an outer surface 54 to guide wind rearward. The horizontal cross-section of the outer surface 54 of the outer air guide 28 includes a burble point 71 at which wind flowing on the outer surface 54 separates rearward from the outer surface 54. The burble point 71 is disposed at a location further rearward than the front end of the engine 14 and further forward than the rear end of the engine 14, and away from the engine 14 outward. The tangent line 72 at the point 71 is parallel to the front-rear direction, or obliquely inclined with respect to the front-rear direction so that it moves away from the vehicle center WO as it moves away rearward from the point 71.