Exhaust Muffler Sliding Inner Sleeve Thermal Expansion

Solution Overview

Problem

Conventional exhaust mufflers with a double structure formed by an outer and inner sleeve face challenges in productivity due to the need for additional components and complex assembly processes, particularly in managing thermal expansion differences between the two sleeves.

Innovation Solution

The exhaust muffler design includes an outer sleeve and an inner sleeve with a peripheral flange portion that holds both sleeves, allowing the inner sleeve to slide between upstream and downstream covers, eliminating the need for an extra support member and simplifying assembly by using identical shapes for the covers and common tooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a support ring is added to allow the inner sleeve to slide relative to the outer sleeve, then the thermal expansion difference between the inner and outer sleeves can be tolerated, but the number of components increases and assembly complexity increases

Engineering Contradiction:

Improvethermal expansion toleranceVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The support ring is merged with the outer sleeve to form an integrated structure. The outer sleeve includes a support ring portion that extends radially inward, eliminating the need for a separate support ring component. This integration maintains the sliding function while reducing component count and assembly complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The outer sleeve is given multiple functions: it serves as both the protective outer structure and as the support ring for the inner sleeve. The support ring portion of the outer sleeve provides both structural support and guides the inner sleeve's sliding motion, combining multiple functions into a single component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a support ring is added to allow the inner sleeve to slide relative to the outer sleeve, then the thermal expansion difference between the inner and outer sleeves can be tolerated, but welding the support ring to the inner sleeve becomes troublesome and productivity decreases

Engineering Contradiction:

Improvethermal expansion toleranceVSAvoidassembly efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The support ring is merged with the outer sleeve to form an integrated structure. The outer sleeve includes a support ring portion that extends radially inward, eliminating the need for a separate support ring component. This integration maintains the sliding function while reducing component count and assembly complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The welding operation is extracted from the assembly process. By making the support ring an integral part of the outer sleeve rather than a separate component, the welding step that would be required to attach the support ring to the inner sleeve is eliminated, improving productivity.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If the inner sleeve is held by an extra support member, then the inner sleeve can slide to accommodate thermal expansion, but the assembly process becomes more complex and time-consuming

Engineering Contradiction:

Improvesliding capabilityVSAvoidassembly time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The support ring is merged with the outer sleeve to form an integrated structure. The outer sleeve includes a support ring portion that extends radially inward, eliminating the need for a separate support ring component. This integration maintains the sliding function while reducing component count and assembly complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 productivity by reducing component count and assembly complexity, while maintaining sound deadening performance and accommodating thermal expansion differences without additional support members.

Implementation Method 1

a sound absorbing material such as glass wool is packed between the outer sleeve and the inner sleeve

Methodology Applied

Scientific EffectSound absorption: Acoustic Absorption

Implementation Method 2

Since the sound absorbing material also serves as a heat insulating material, the temperature of the outer sleeve becomes lower than that of the inner sleeve

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

there is a difference between the thermal expansion amount of the outer sleeve and that of the inner sleeve

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8985272B1Exhaust muffler for vehicle

Publication Date: 2015.03.24 KAWASAKI MOTORS LTD

AI summary

An exhaust muffler for a vehicle includes: a sleeve portion made up of an outer sleeve and an inner sleeve; an upstream side cover that has an exhaust entrance and that closes an upstream side opening of the sleeve portion; and a downstream side cover that has an exhaust exit and that closes a downstream side opening of the sleeve portion. At least one of the upstream side cover and the downstream side cover has a peripheral flange portion that externally holds the sleeve portion. The peripheral flange portion has an outer sleeve holding portion and an inner sleeve holding portion. One end portion of the inner sleeve abuts on the inner sleeve holding portion so as to be slidable in a length direction of the inner sleeve. One end portion of the outer sleeve is fixed to the outer sleeve holding portion.