Nested Exhaust Muffler Pipes for Acoustic Tuning

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Solution Overview

Problem

Existing mufflers for internal combustion engine exhaust systems face challenges in adapting to desired acoustic profiles while minimizing pressure loss and flow noise.

Innovation Solution

The muffler design includes adjustable inlet and outlet pipes with varying cross-sectional geometries and lengths, along with passage openings and exhaust gas flaps, to optimize acoustic behavior and reduce flow resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the outlet pipe is inserted deeply into the inlet pipe to improve acoustic behavior, then the acoustic profile can be adjusted efficiently, but the flow resistance increases leading to flow noise and power losses

Engineering Contradiction:

Improveacoustic profile adjustmentVSAvoidpower losses and flow noise

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The outlet pipe is inserted into the inlet pipe in a nested configuration, allowing the outlet pipe to be positioned within the inlet pipe's flow path. This nesting arrangement enables acoustic optimization through controlled interaction between the pipes while maintaining adequate flow cross-section to minimize resistance and energy losses.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The inlet pipe features a funnel-like tapering end region that transitions from a smaller cross-section to a larger cross-section. This local geometric variation optimizes flow characteristics at the insertion point, reducing flow resistance and noise while allowing the outlet pipe to be effectively positioned for acoustic tuning.

Inventive Principle:

Principle #3Local quality

2Productivity

If passage openings are provided in the pipe walls to couple chambers, then exhaust gas can be effectively routed between chambers, but exhaust gas may escape into the expansion chamber instead of flowing through the outlet pipe

Engineering Contradiction:

Improveexhaust gas routing efficiencyVSAvoidexhaust gas leakage into expansion chamber

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

Passage openings are strategically positioned in the pipe walls at locations where they allow exhaust gas to transition between chambers while preventing premature escape into the expansion chamber. The openings are placed upstream of the expansion chamber region, ensuring exhaust gas flows through the intended path via the outlet pipe first.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The inlet pipe acts as an intermediary component that receives exhaust gas from the engine and directs it through the outlet pipe into the expansion chamber. The funnel-like tapering design of the inlet pipe mediates the flow transition, ensuring proper routing while the passage openings in the pipe walls facilitate controlled gas exchange between chambers.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3514342B1Sound absorber

Publication Date: 2020.07.22 EBERSPACHER EXHAUST TECH GMBH & CO

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AI summary

A silencer for an exhaust system of an internal combustion engine comprises a silencer housing (14) and at least one exhaust pipe group (19), wherein the at least one exhaust pipe group (19) comprises: - an outlet pipe (20) open to an expansion chamber (26) formed in the silencer housing (14), wherein exhaust gas introduced via the at least one exhaust pipe group (19) leaves the silencer housing (16) via the outlet pipe (20), - a first inlet pipe (38), wherein the first inlet pipe (38) has an inlet pipe end region (40) inserted into and extending in the outlet pipe (20), - a second inlet pipe (48), wherein the second inlet pipe (48) is open to the expansion chamber (26).