Resilient Retaining Strip Static Mixer for Exhaust Gas Thermal Stress

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Solution Overview

Problem

Static mixers for exhaust gas systems in internal combustion engine vehicles face damage risks due to high exhaust gas temperatures and temperature changes, particularly in rectangular grid structures where material expansion leads to cracks and failures.

Innovation Solution

The use of resilient retaining strips with S-shaped curvature and elastic support in the mixer plane to equalize temperature-induced stresses, allowing for the linking of retaining strips in a way that accommodates material deformations and reduces the risk of damage, while also simplifying production and reducing component diversity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rectangular grid structure with rigid retaining strips is used, then the mixer provides structural stability and simple construction, but the mixer is prone to cracks and failures at high temperatures due to thermal expansion stresses

Engineering Contradiction:

Improveresistance to thermal damageVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The retaining strips are made resilient in at least partial regions, changing the mechanical parameter from rigid to elastic. This allows the strips to reversibly equalize thermal expansions at high temperatures, preventing cracks and failures while maintaining structural integrity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The retaining strips are made curved, particularly with S-shaped curvature in given regions. This curved geometry inherently provides resilience and flexibility to accommodate thermal expansion stresses, eliminating the need for complex expansion joints while maintaining structural stability

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If curved retaining strips with S-shaped regions are used, then the mixer accommodates thermal expansion effectively, but the manufacturing complexity increases

Engineering Contradiction:

Improvedamage resistanceVSAvoidproduction complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The mixer structure is segmented into multiple retaining strips with specific regions made resilient. This segmentation allows the curved, resilient portions to be strategically placed only where thermal expansion occurs, rather than making the entire structure complex, thus balancing manufacturability with thermal resistance

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If multiple different retaining strip configurations are used, then the mixer optimizes performance for different flow patterns, but the production costs increase due to component diversity

Engineering Contradiction:

Improveflow pattern adaptabilityVSAvoidproduction cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The retaining strips are designed with multi-functionality: they provide structural support, induce transverse flow for mixing, and accommodate thermal expansion through resilience. The S-shaped curved regions serve both structural and flow-guiding functions, reducing the need for separate components and lowering production costs

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 significantly reduces the risk of mixer damage at high exhaust gas temperatures by allowing for reversible expansion equalization, simplifying production, and reducing production costs through the use of identical parts and diverse configurations.

Implementation Method 1

the at least one retaining strip is made resilient at least in partial regions and/or is elastically supported in the plane of the mixer... the resilient retaining strip areas can reversibly equalize the expansions

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

temperature-induced stresses due to material expansion... the regions of curvature are each formed by a retaining strip region which is curved in an S shape

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9003771B2Static mixer for an exhaust gas system of an internal combustion engine-driven vehicle, in particular motor vehicle

Publication Date: 2015.04.14 AUDI AG

AI summary

The invention relates to a static mixer for an exhaust gas system of an internal combustion engine-driven vehicle, with a plurality of flow guide elements which influence the flow of an exhaust gas stream and which are inclined at a given angle relative to the mixer plane and are held in the exhaust gas channel by means of at least one retaining strip. According to the invention the at least one retaining strip is made resilient at least in partial regions and/or is elastically supported in the plane of the mixer.