Exhaust Pipe Bracket Mounting for Vibration Control

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Solution Overview

Problem

Straddled vehicles face challenges in stably supporting exhaust pipes with catalysts positioned upstream, as increased pipe thickness to mitigate stress leads to weight gain, and direct support on the vehicle body frame can cause vibration, necessitating additional weight and components to suppress it.

Innovation Solution

A straddled vehicle design where the catalyst is positioned in the exhaust pipe's upstream portion, supported by a bracket directly attached to the internal combustion engine, avoiding the need for increased pipe thickness and weight, with the bracket's fixed portion positioned between the catalyst and engine to stabilize the pipe.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the thickness of the exhaust pipe is increased to reduce stress, then the stress resistance is improved, but the weight of the exhaust pipe increases

Engineering Contradiction:
Improvestress resistanceVSAvoidweight of exhaust pipe
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The exhaust pipe support system is segmented into multiple support portions along the exhaust pipe. By distributing the support points, the stress on any single section is reduced, allowing the use of thinner pipe walls while maintaining overall structural strength. This segmentation approach enables weight reduction without sacrificing stress resistance.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If the exhaust pipe is directly supported on the vehicle body frame, then the support stability is improved, but vibration occurs due to resonance

Engineering Contradiction:
Improvesupport stabilityVSAvoidvibration
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

A bracket is introduced as an intermediary component between the exhaust pipe and the vehicle body frame. The bracket serves as a mediator that decouples the direct connection, preventing resonance transmission while maintaining support stability. This intermediary structure allows the exhaust pipe to be firmly supported without direct contact that would cause vibrational resonance with the frame.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If additional support components are added to suppress vibration, then the vibration control is improved, but the weight of the support system increases

Engineering Contradiction:
Improvevibration suppressionVSAvoidweight of support system
Core Design Contradiction:
Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The bracket is designed to perform multiple functions simultaneously: it provides structural support for the exhaust pipe, acts as a vibration isolation element through its mounting configuration, and distributes mechanical loads across multiple attachment points. By making the bracket multi-functional, separate vibration suppression components are eliminated, preventing additional weight increase while maintaining effective vibration control.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4080023B1Straddled vehicle
Publication Date: 2023.10.11 YAMAHA MOTOR CO LTD
  • EP4080023B1 patent drawingFigure 1
  • EP4080023B1 patent drawingFigure 2
  • EP4080023B1 patent drawingFigure 3

AI summary

An object is to stably support a portion of an exhaust pipe where a catalyst is arranged, and to suppress resonation between this portion of the exhaust pipe and a vehicle body frame. An exhaust pipe (10) includes a front portion (12) located forward relative to a cylinder head (3) of an internal combustion engine (4), and a side portion (13) located sideward of a cylinder head (3). A catalyst (45) is arranged inside the front portion (12) or the side portion (13) of the exhaust pipe (10). A motorcycle (50) includes a bracket (20) including a fixed portion (21) that is fixed to the side portion (13) or the front portion (12) of the exhaust pipe (10). A front end (21f) of the fixed portion (21) is located forward relative to a rear end (45b) of the catalyst (45), and a rear end (21b) of the fixed portion (21) is located rearward relative to a front end (45f) of the catalyst (45). The bracket (20) is supported directly on the internal combustion engine (4).