Motorcycle Air Cleaner Intake Layout for Sound and Rain Protection

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Solution Overview

Problem

Existing straddled vehicles face challenges in allowing riders to efficiently hear intake sounds from the air cleaner while minimizing the entry of droplets, such as rainwater, into the intake port.

Innovation Solution

The intake port of the air cleaner is positioned downward and rearward of the fuel tank, with through holes in the tank cover aligned to overlap with the fuel tank, and shielding members to prevent droplet entry, creating a sound transmission path that directs intake sounds upward for the rider to hear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the intake port is positioned upwardly close to the rider's head, then the rider can efficiently hear the intake sound, but droplets of rainwater are likely to enter the intake port

Engineering Contradiction:
Improverider's ability to hear intake soundVSAvoiddroplet entry into intake port
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a sound transmission path as an intermediary mechanism between the intake port and the rider's head. This path includes a sound transmission hole in the tank cover and a sound transmission chamber that guides sound waves upward without requiring the intake port itself to be positioned upward, thus preventing droplet entry while maintaining sound transmission capability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent separates the sound transmission function from the air intake function by creating a dedicated sound transmission path in the vertical dimension. The sound transmission hole is positioned in the tank cover above the fuel tank, creating a separate acoustic channel that allows sound to reach the rider's head without exposing the intake port to rainwater

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

2Object-affected harmful factors

If the intake port is positioned downward and rearward below the fuel tank, then droplet entry is reduced, but the rider cannot efficiently hear the intake sound

Engineering Contradiction:
Improvedroplet entry into intake portVSAvoidrider's ability to hear intake sound
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The sound transmission path acts as an intermediary that bridges the spatial gap between the downward-positioned intake port and the rider's head. The sound transmission hole in the tank cover and the sound transmission chamber carry sound waves upward, allowing the rider to hear intake sounds even when the intake port remains in a protected downward position

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the air intake system into separate functional components: the intake port for air entry, the fuel tank for fuel storage, and the sound transmission path for acoustic signal delivery. This segmentation allows each component to be optimized independently - the intake port can be positioned for droplet protection while the sound transmission path delivers audio to the rider

Inventive Principle:
Principle #1Segmentation

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

Riders can effectively hear intake sounds while reducing droplet ingress into the air cleaner, enhancing the driving experience by auditory feedback on engine state.

Implementation Method 1

a sound transmission space is formed between the air cleaner and the tank cover so as to continuously extend from the intake port of the air cleaner to the one or plurality of through holes of the tank cover

Methodology Applied
Scientific EffectSound transmission: Sound

Data Source

PatentEP4372224B1Straddled vehicle
Publication Date: 2026.02.25 YAMAHA MOTOR CO LTD
  • EP4372224B1 patent drawingFigure 1
  • EP4372224B1 patent drawingFigure 2
  • EP4372224B1 patent drawingFigure 3

AI summary

There is disclosed a straddled vehicle (100) including a fuel tank (10), a tank cover (20) and an air cleaner (30); the fuel tank 10 being provided at a position forward of a seat (50) in the vehicle and above an engine (5); the tank cover 20 being provided to cover the fuel tank (10) at least from above; the air cleaner (30) having an intake port (39); the intake port 39 being opened upwardly at a position farther downward than the fuel tank (10) and farther rearward than a center (CP) of the fuel tank (10) in the vehicle (100); one or a plurality of through holes (TH) overlapping with the fuel tank (10) in plan view are formed in the tank cover (20).