Motorcycle Radiator Grille Louver Layout for Even Cooling Airflow

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Solution Overview

Problem

The existing straddled vehicles suffer from uneven air distribution across the radiator, with more air being supplied to the outer sections compared to the middle section, leading to uneven cooling performance.

Innovation Solution

The design includes a radiator grille with louvers aligned in the transverse direction, where the louver closest to the vehicle center plane projects more forward than the others, ensuring even air distribution by increasing airflow to the central region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the louver closest to the vehicle center plane projects less forward than other louvers, then the radiator grille structure is simpler, but the air supply distribution to the radiator becomes uneven

Engineering Contradiction:
Improveradiator grille structure simplicityVSAvoidair supply distribution uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by making the first louver (closest to vehicle center plane) project more forward than the second and third louvers. This asymmetric configuration creates a larger first air supply area compared to the second air supply area, directing more air flow to the middle section of the radiator. This resolves the contradiction by using geometric asymmetry to achieve uniform air distribution while maintaining manufacturing simplicity.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by creating different projection distances for different louvers based on their positions. The first louver has a greater forward projection than the second and third louvers, creating localized variations in air supply areas. This ensures that the middle section of the radiator (served by the first louver) receives appropriate air flow, achieving uniform overall distribution through localized structural differences.

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If the first louver projects more forward than other louvers, then the air supply to the middle section of the radiator increases, but the radiator grille becomes more complex

Engineering Contradiction:
Improveair flow amount to middle sectionVSAvoidradiator grille structure
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The asymmetric projection design where the first louver extends further forward than the second and third louvers creates a larger air supply area for the middle section. This simple geometric modification increases air flow to the middle section without requiring complex mechanical components, adjustable mechanisms, or additional parts, thus resolving the contradiction between air flow quantity and structural complexity.

Inventive Principle:
Principle #4Asymmetry

3Device complexity

If all louvers project equally forward, then the radiator grille structure is uniform and simple, but the outer sections receive more air than the middle section

Engineering Contradiction:
Improveradiator grille structure uniformityVSAvoidair distribution evenness
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent deliberately breaks the symmetry of uniform louver projection by making the first louver project more forward than the second and third louvers. This creates a non-uniform structure that compensates for the natural tendency of air flow to favor outer sections. The asymmetric design achieves even air distribution by creating a larger air supply area for the middle section, resolving the contradiction between structural uniformity and air distribution evenness.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP4541624B1Radiator grille of a straddled vehicle
Publication Date: 2026.03.11 YAMAHA MOTOR CO LTD
  • EP4541624B1 patent drawingFigure 1
  • EP4541624B1 patent drawingFigure 2
  • EP4541624B1 patent drawingFigure 3

AI summary

A straddled vehicle 1 includes a head tube 3, a front fork 7, a front wheel 8, a left shroud 31L, a right shroud 31R, a radiator 11, and a radiator grille 20. The radiator 11 is located rearward of the front fork 7 and between the left shroud 31L and the right shroud 31R. The radiator grille 20 is located rearward of the front fork 7, between the left shroud 31L and the right shroud 31R, and forward of the radiator 11. The radiator grille 20 includes a plurality of louvers 40. The louvers 40 are lined in a transverse direction Y. It is assumed that, among all the louvers 40, a louver 40 closest to a vehicle center plane C is a first louver 41. The first louver 41 projects more forward than the louvers 40 other than the first louver 41.