Straddle Vehicle Exhaust Muffler Resonator Chamber Design

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Solution Overview

Problem

Straddle-type vehicles with a single resonator chamber face challenges in managing exhaust heat and sound, as existing designs often require additional resonator chambers to effectively suppress these issues, and there is a design constraint on muffler length due to considerations like noise, fuel consumption, and output characteristics.

Innovation Solution

The exhaust structure incorporates a resonator chamber positioned at the muffler's downstream end, surrounded by noise-damping material, with a double-wall structure and a communicating pipe configuration that utilizes glass wool for thermal insulation and sound reduction, allowing for efficient drainage of moisture and optimized placement of exhaust components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a single resonator chamber is used in the muffler, then the muffler length is reduced, but the ability to suppress uneven burns and exhaust sound deteriorates

Engineering Contradiction:

Improvemuffler lengthVSAvoidexhaust sound and uneven burns

Core Design Contradiction:

Length of moving objectVSObject-generated harmful factors

Solution Approach 1:

The resonator chamber is nested within the expansion chamber structure, with the resonator chamber positioned inside or adjacent to the expansion chambers R1 and R2. This nested configuration allows the resonator chamber to share space with the expansion chambers, reducing the overall muffler length while maintaining both resonator and expansion chamber functions for effective sound and heat management

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Glass wool is selectively applied only around the resonator chamber R3 rather than throughout the entire muffler. This localized insulation approach targets the specific area where heat management is most critical for the resonator chamber, effectively suppressing uneven burns and exhaust sound without requiring additional length or material throughout the whole structure

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If additional resonator chambers are added to suppress exhaust heat and sound, then the harmful factors are reduced, but the muffler length increases

Engineering Contradiction:

Improveexhaust heat and soundVSAvoidmuffler length

Core Design Contradiction:

Object-generated harmful factorsVSLength of moving object

Solution Approach 1:

The resonator chamber R3 is merged with the expansion chamber structure, where the resonator chamber is positioned at the downstream end within or adjacent to the expansion chambers. This merging allows a single resonator chamber to work synergistically with the expansion chambers for both sound reduction and heat management, eliminating the need for separate additional resonator chambers that would increase length

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The resonator chamber R3 serves multiple functions: it acts as a resonator for sound reduction, a thermal management zone for suppressing uneven burns, and integrates with the expansion chambers for both sound and heat control. This multi-functionality allows a single chamber to replace what would traditionally require multiple separate chambers, maintaining effectiveness while reducing overall muffler length

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 uneven burns and exhaust sound, even with a single resonator chamber, while maintaining design quality and adhering to length constraints, by leveraging the lower temperature resonator chamber and glass wool insulation.

Implementation Method 1

a noise-damping material (137) being provided on an inner circumference of the outer tube (133), the resonator chamber (R3) is provided in a most downstream part of the muffler (36)... surroundings of the resonator chamber (R3) are surrounded by the noise-damping material (137)

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Implementation Method 2

a noise-damping material (137) being provided on an inner circumference of the outer tube (133)... surroundings of the resonator chamber (R3) are surrounded by the noise-damping material (137)

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

muffler (36) including a resonator chamber (R3) for exhaust sound reduction

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9803522B2Exhaust structure of straddle-type vehicle, and vehicle incorporating same

Publication Date: 2017.10.31 HONDA MOTOR CO LTD

AI summary

An exhaust structure for a straddle-type vehicle includes a muffler having an outer tube constituting an outer circumferential member of the muffler; first and second separators defining expansion chambers in the outer tube; a body end member arranged at the downstream end of the outer tube; and glass wool provided on the inner circumference of the outer tube. The muffler further includes a resonator chamber provided in the most downstream portion of the muffler. The resonator chamber is formed by the outer tube, the body end member and the second separator situated closest to the body end member. The surroundings of the resonator chamber are surrounded by the glass wool. Such exhaust structure of a straddle-type vehicle is capable of taking measures against exhaust heat and exhaust sound even with a configuration where there is only one, single resonator chamber.