Exhaust Muffler Inner Shell Thermal Protection

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Solution Overview

Problem

Internal combustion engine exhaust systems face thermal discoloration issues due to hot combustion gases, which can lead to tarnishing of visible components like exhaust mufflers, causing aesthetic and maintenance concerns.

Innovation Solution

An exhaust muffler design featuring a muffler housing with an outer shell and an inner shell that reduces thermal interaction by creating an intermediate space, supported at specific areas to prevent direct contact and discoloration, while maintaining structural integrity and muffling efficiency through partitions and holding materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the outer shell is directly exposed to hot combustion exhaust gases, then the muffler structure is simple, but the outer shell suffers thermal discoloration and aesthetic degradation

Engineering Contradiction:

Improvemuffler structureVSAvoidthermal discoloration

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

An inner shell is introduced as an intermediary component between the hot exhaust gases and the outer shell. The inner shell absorbs the thermal load and protects the outer shell from direct thermal exposure, preventing discoloration while maintaining a relatively simple overall structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The inner shell is nested within the outer shell, creating a concentric structure where the inner shell is positioned inside the muffler interior and the outer shell encloses the inner shell. This nested arrangement provides thermal protection without significantly increasing device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Object-affected harmful factors

If the inner shell is positioned close to the outer shell to maximize shielding, then thermal protection is improved, but the intermediate space is minimized compromising structural stability

Engineering Contradiction:

Improvethermal protectionVSAvoidstructural stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The inner shell is supported at specific local areas by the outer shell rather than being uniformly spaced or in continuous contact. This localized support approach provides sufficient structural stability while maintaining an intermediate space that allows for thermal protection and exhaust gas flow.

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If the inner shell is directly supported at the outer shell to prevent clapping noises, then positioning stability is improved, but thermal shielding effectiveness is reduced

Engineering Contradiction:

Improvepositioning stabilityVSAvoidthermal shielding

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The inner shell is supported at discrete local positions by the outer shell through support areas, rather than being in continuous contact. This localized support configuration prevents clapping noises and ensures positioning stability while preserving the intermediate space needed for effective thermal shielding in the majority of the surface area.

Inventive Principle:

Principle #3Local quality

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

The solution effectively prevents thermally induced discoloration of the outer shell, maintains structural strength, and minimizes noise by ensuring the inner shell is securely positioned without direct contact, thus enhancing the durability and appearance of exhaust mufflers.

Implementation Method 1

the inner shell covers the outer shell in at least some areas on an inner side facing the muffler interior... the direct thermal interaction of the hot combustion exhaust gases... with the outer shell... is avoided

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

The hot combustion exhaust gases introduced into the muffler interior at first come into contact with the inner shell and lead to a relatively strong thermal load of the inner shell. However, a contact of the exhaust gases also with the outer shell... cannot cause tarnishing of the outer shell, since the exhaust gases are cooled off during contact with the inner shell

Methodology Applied

Scientific EffectConvection cooling: Convection

Data Source

PatentUS11795847B2Exhaust muffler

Publication Date: 2023.10.24 PUREM GMBH

AI summary

An exhaust muffler for an exhaust system of an internal combustion engine includes a muffler housing (12) with an outer shell (14) enclosing a muffler interior (22), through which exhaust gas can flow. An inner shell (54) is arranged in the muffler interior (22) and covers the outer shell (14) in at least some areas on an inner side (52) facing the muffler interior (22).