Motorcycle Rear Radar Layout for Tail Light Clearance

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Solution Overview

Problem

Straddled vehicles face challenges in integrating a radar on the rear portion without obstructing the tail light's emitted light and being susceptible to vibration due to limited space and low rigidity of rear fenders and seat cowl structures.

Innovation Solution

The radar is positioned on the seat frame, specifically arranged forward of the tail light, downward from the seat frame's upper end, rearward from the rear fender's front end, and upward from the rear fender's lower end, supported by a robust seat frame that minimizes vibration transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the radar is made larger to improve detection performance, then the radar detection capability is improved, but the radar blocks emitted light from the tail light

Engineering Contradiction:
Improveradar detection capabilityVSAvoidblockage of tail light emitted light
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The radar is repositioned from the traditional rear fender area to the seat frame structure, utilizing the three-dimensional space above and behind the seat. This spatial relocation allows the radar to maintain its detection function while being positioned forward relative to the tail light, eliminating the light blockage issue.

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

2Ease of manufacture

If the radar is attached to the rear fender to simplify installation, then the ease of manufacture is improved, but the radar is influenced by vibration due to low rigidity of the rear fender

Engineering Contradiction:
Improveease of radar installationVSAvoidvibration influence on radar
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The radar is extracted from the rear fender mounting location and relocated to the seat frame. This separation removes the radar from the vibration-prone rear fender structure while maintaining ease of installation through the seat frame's integrated mounting points.

Inventive Principle:
Principle #2Taking out (Extraction)

3Illumination intensity

If the radar is arranged upward of the tail light to avoid blocking light, then the tail light visibility is improved, but the radar is attached to the seat cowl which has low rigidity and is susceptible to vibration

Engineering Contradiction:
Improvetail light visibilityVSAvoidvibration influence on radar
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The seat frame serves as an intermediary structure between the radar and the vehicle body. By mounting the radar on the rigid seat frame rather than directly on the tail light assembly or rear fender, the system achieves both good tail light visibility and reduced vibration influence through the seat frame's structural properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Object-affected harmful factors

If the rigidity of the rear fender is increased to reduce vibration influence on the radar, then the vibration resistance is improved, but the size and weight of the rear fender increase

Engineering Contradiction:
Improvevibration influence on radarVSAvoidweight of rear fender
Core Design Contradiction:
Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

Instead of modifying the rear fender to increase its rigidity, the radar is extracted from the rear fender mounting location and relocated to the seat frame. This approach achieves vibration reduction without requiring any changes to the rear fender's weight or size.

Inventive Principle:
Principle #2Taking out (Extraction)

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 arrangement allows for a larger radar without blocking tail light visibility and reduces vibration influence, ensuring stable operation and compact integration.

Implementation Method 1

The radar includes a transmitter that transmits radio waves, a receiver that receives radio waves (reflected waves) that have been reflected off objects such as other vehicles

Methodology Applied
Scientific EffectRadio wave transmission: Radar

Implementation Method 2

a receiver that receives radio waves (reflected waves) that have been reflected off objects such as other vehicles

Methodology Applied
Scientific EffectRadio wave reflection: Reflection

Data Source

PatentEP4059794B1Straddled vehicle with rear radar
Publication Date: 2025.11.26 YAMAHA MOTOR CO LTD
  • EP4059794B1 patent drawingFigure 1
  • EP4059794B1 patent drawingFigure 2
  • EP4059794B1 patent drawingFigure 3

AI summary

A motorcycle (1) includes a radar (20) including a transmitter (21) that transmits radio waves, a receiver (22) that receives radio waves, and a casing (23) that houses the transmitter (21) and the receiver (22). The radar (20) is supported on a seat frame (10). At least a portion of the radar (20) is arranged forward relative to a rear end (14b) of a tail light (14), downward relative to an upper end (10t) of the seat frame (10), rearward relative to a front end (12f) of a rear fender (12) and upward relative to a lower end (12d) of the rear fender (12).