Motorcycle Silencer with Partitioned Chambers and Throttle

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Solution Overview

Problem

Conventional silencers for motorcycles face challenges in achieving effective silencing performance while being compact in size, due to limited vehicle space, which requires a balance between length, sectional area, and noise attenuation.

Innovation Solution

A silencer design featuring a main body with partitioned chambers, including a first chamber, a resonance chamber, and a second chamber, where a conduit with resonance communication holes and a throttle portion is used to extend the sound attenuation path, supported by partition walls to manage heat and flow, and includes a discharge pipe for efficient exhaust gas discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the silencer uses a conventional structure with limited partitioning, then the device complexity is low, but the silencing performance is insufficient and the size cannot be reduced

Engineering Contradiction:

Improvesilencing performanceVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The silencer is divided into three distinct chambers (first chamber, resonance chamber, and second chamber) separated by partition walls. This segmentation allows each chamber to perform specific functions: the first chamber for initial exhaust gas collection, the resonance chamber for noise attenuation through acoustic resonance, and the second chamber for final discharge. This functional segmentation improves silencing performance while maintaining manageable structural complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A conduit acts as an intermediary element connecting the chambers and managing exhaust gas flow. The conduit includes multiple communication holes (resonance communication hole, upstream side communication hole, downstream side communication hole) that mediate between different chambers, allowing controlled gas flow and acoustic interaction while maintaining the overall structural integrity and organization of the silencer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the silencer length and sectional area are increased to improve silencing performance, then the attenuation characteristic improves, but the silencer size increases and cannot be downsized for vehicle space constraints

Engineering Contradiction:

Improveattenuation characteristicVSAvoidsilencer length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The conduit is nested within the silencer body, extending through multiple chambers. The resonance communication hole is positioned in the conduit wall, allowing acoustic coupling between the resonance chamber and the conduit without requiring additional external components. This nesting approach enables effective noise attenuation through the acoustic path while maintaining a compact overall silencer size that fits vehicle space constraints.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If the conduit is positioned close to the resonance chamber, then the structure is compact, but the attenuation characteristic is reduced due to insufficient sound path length

Engineering Contradiction:

Improveattenuation characteristicVSAvoidconduit length

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The conduit extends in the longitudinal dimension of the silencer body, passing through the resonance chamber and connecting to the second chamber. By utilizing the longitudinal space and positioning communication holes at different locations along the conduit, the design achieves sufficient sound path length for effective attenuation while maintaining a compact cross-sectional arrangement that fits within the vehicle space constraints.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design enhances sound attenuation characteristics, reduces the silencer's size and weight, maintains low temperatures in critical areas, and improves engine output power by optimizing the flow and discharge of exhaust gases.

Implementation Method 1

a resonance chamber provided between the first and second chambers

Methodology Applied

Scientific EffectAcoustic resonance: Resonance

Implementation Method 2

a throttle portion which throttles the exhaust path is provided between the upstream side communication hole and the downstream side communication hole

Methodology Applied

Scientific EffectFlow restriction: Pressure Gradient

Data Source

PatentUS9657615B2Silencer for internal combustion engine

Publication Date: 2017.05.23 HONDA MOTOR CO LTD

AI summary

A silencer includes conduit with a downstream end portion configured from a tubular member which includes a conduit discharge port extending through a silencer main body and discharges exhaust gas to the outside therethrough. The tubular member includes a resonance communication hole communicating with a resonance chamber and an upstream side communication hole and a downstream side communication hole communicating with a second chamber. A barrier wall serving as a throttle portion for throttling an exhaust path at an intermediate location of the tubular member is provided in the inside of the tubular member and between the upstream side communication hole and the downstream side communication hole.