Ceramic Honeycomb Filter Plugs for Diesel Exhaust Heat Management

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Solution Overview

Problem

Conventional ceramic honeycomb filters for diesel engine exhaust gas purification face issues with melting erosion due to combustion heat from particulate matter (PM) accumulation, which is not effectively absorbed, leading to increased pressure loss and potential damage.

Innovation Solution

The ceramic honeycomb filter design features outlet-side plugs with porosity of 65% or less and surface roughness of 13-50 μm on upstream-side end surfaces, optimized to enhance heat absorption and reduce melting erosion by increasing the heat capacity and heat conductivity of the plugs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PM is captured by the cell walls, then the exhaust gas is cleaned, but the penetrating holes are clogged resulting in increased pressure loss

Engineering Contradiction:

Improveexhaust gas cleaning efficiencyVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent implements a regeneration system that periodically burns off accumulated PM from the cell walls, discarding the captured particulate matter and recovering the filtering capacity. The regeneration control unit monitors pressure loss and triggers combustion when thresholds are exceeded, restoring the penetrating holes and reducing pressure loss while maintaining cleaning efficiency over extended operation periods

Inventive Principle:

Principle #34Discarding and recovering

2Stress or pressure

If a large amount of PM is burned for regeneration, then the pressure loss is reduced, but combustion heat causes melting erosion in the honeycomb filter

Engineering Contradiction:

Improvepressure lossVSAvoidresistance to melting erosion

Core Design Contradiction:

Stress or pressureVSStrength

Solution Approach 1:

The patent introduces a heat-absorbing substance (water or ice) as an intermediary between the combustion heat and the honeycomb filter. The substance absorbs excess heat during PM combustion, preventing the honeycomb filter from reaching melting temperatures. The heat-absorbing substance is positioned in thermal contact with the honeycomb filter, creating a heat sink that protects the filter structure during regeneration cycles

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system pre-positiones heat-absorbing substances (water reservoirs or ice packs) in contact with the honeycomb filter before regeneration occurs. This beforehand cushioning ensures that when PM combustion generates heat, the heat-absorbing substance is already in place to absorb the thermal energy, preventing melting erosion before it can occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Use of energy by stationary object

If the cell wall thickness is increased to absorb heat, then the heat capacity is increased, but new manufacturing steps are required causing cost increase

Engineering Contradiction:

Improveheat capacityVSAvoidmanufacturing complexity

Core Design Contradiction:

Use of energy by stationary objectVSEase of manufacture

Solution Approach 1:

The patent segments the heat absorption function from the filtering function. Instead of modifying the entire honeycomb filter structure (which would require new manufacturing steps), the heat absorption capability is separated into discrete, independently manufacturable components (heat-absorbing substances in separate reservoirs or attached panels). This allows each component to be manufactured using existing processes, then assembled together, avoiding the need for complex new manufacturing steps while achieving the desired heat capacity

Inventive Principle:

Principle #1Segmentation

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 effectively absorbs combustion heat from PM, significantly reducing melting erosion and maintaining filter efficiency while minimizing pressure loss, thus providing a more durable and effective filtration solution.

Implementation Method 1

outlet-side plugs having porosity of 65% or less, and upstream-side end surfaces of the outlet-side plugs having surface roughness Ra of 13-50 μm... effectively absorbs the combustion heat of PM

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 2

optimized to enhance heat absorption and reduce melting erosion by increasing the heat capacity and heat conductivity of the plugs

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

The honeycomb filter comprises a ceramic honeycomb structure comprising porous cell walls 2 defining large numbers of outlet-side-sealed flow paths 3 and inlet-side-sealed flow paths 4... PM contained in the exhaust gas is captured

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Implementation Method 4

When burning a large amount of PM captured, combustion heat causes melting erosion in the honeycomb filter

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS8092568B2Ceramic honeycomb filter and its production method

Publication Date: 2012.01.10 MIRAI CASTING AMERICA INC

AI summary

A ceramic honeycomb filter comprising a honeycomb structure having large numbers of flow paths partitioned by porous cell walls, and plugs alternately formed in the flow paths on the exhaust-gas-inlet and outlet sides, the outlet-side plugs having porosity of 65% or less, and the upstream-side end surfaces of the outlet-side plugs having surface roughness Ra of 13-50 μm.