Honeycomb Structure Plugging Gap Design for Thermal Shock Resistance

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Solution Overview

Problem

Existing honeycomb structures for diesel particulate filters face challenges in maintaining thermal shock resistance while ensuring collection efficiency and bonding strength, particularly due to uneven plugging thickness and potential gaps between plugging portions and partition walls.

Innovation Solution

A honeycomb structure with plugging portions having a predetermined gap size of 20 μm or more between the plugging portion and the partition wall, where the gap's axial length is 50% or more and less than 95% of the plugging portion's length, and its face vertical length is 20% or more and 50% or less of the cell's inner surface, formed in at least ⅓ of the plugging portions, along with a manufacturing method using a mask and pressurizing member to fill the plugging material at an acute angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If plugging portions are formed with uniform thickness, then manufacturing process is simple, but thermal shock stress concentrates at the boundary between partition wall and plugging portion causing cracks

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidthermal shock resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The plugging portion is designed with asymmetric thickness distribution: thicker at the boundary with the partition wall and thinner toward the cell center. This asymmetric configuration reduces thermal shock stress concentration at the boundary while maintaining manufacturing feasibility through a single-step filling process.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The plugging material is formulated with locally varying properties, specifically having different viscosity characteristics in different regions. The material exhibits higher viscosity near the partition wall boundary to maintain structural integrity and reduce stress concentration, while having lower viscosity in the center region for complete filling.

Inventive Principle:

Principle #3Local quality

2Strength

If plugging portions are made thicker, then bonding strength with partition wall improves, but collection efficiency of particulate matter decreases

Engineering Contradiction:

Improvebonding strengthVSAvoidcollection efficiency

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The plugging portion implements local quality variation with thicker regions at the partition wall boundary for enhanced bonding strength, and thinner regions toward the cell center for maintained collection efficiency. This localized thickness optimization resolves the contradiction between bonding strength and collection efficiency.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The asymmetric thickness distribution of the plugging portion, being thicker at the boundary and thinner in the center, simultaneously achieves both objectives: stronger bonding at the interface and sufficient collection efficiency in the cell region.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If gaps are formed between plugging portion and partition wall, then resistance to thermal shock improves, but bonding strength may be compromised

Engineering Contradiction:

Improvethermal shock resistanceVSAvoidbonding strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The plugging material exhibits locally varying viscosity: higher viscosity near the partition wall to ensure strong bonding, and lower viscosity in the center region to form controlled gaps. This local quality variation allows simultaneous achievement of bonding strength and thermal shock resistance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The viscosity parameter of the plugging material is changed spatially, with the material transitioning from high viscosity near the partition wall to lower viscosity toward the cell center. This parameter change enables the formation of gaps that improve thermal shock resistance while maintaining bonding strength through the high-viscosity region.

Inventive Principle:

Principle #35Parameter changes

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 acts as a thermal stress buffer, preventing breakdown from thermal shock and maintaining sufficient bonding strength while maintaining collection efficiency, thus enhancing resistance to thermal shock and ensuring effective particulate matter collection.

Implementation Method 1

This configuration acts as a thermal stress buffer, preventing breakdown from thermal shock

Methodology Applied

Scientific EffectThermal stress buffer: Thermal Shock

Data Source

PatentUS7858168B2Honeycomb structure and manufacturing method of the same

Publication Date: 2010.12.28 NGK INSULATORS LTD

AI summary

There is disclosed a honeycomb structure in which while sufficiently maintaining a collection efficiency and a bonding strength of a plugging portion, a thermal shock resistance is improved. A plugging portion 32 is formed in the end of each cell 3 of a honeycomb structure 1, and a gap 34 having a size of 20 μm or more is formed between the plugging portion 32 and each partition wall 2. Moreover, the length of the gap 34 in the axial direction is 50% or more and less than 95% of the length of the plugging portion 32 in the axial direction, the length of the gap in a face vertical to the axial direction is 20% or more and 50% or less of the length of the inner peripheral surface of the cell 3, and the gaps are formed in at least ⅓ of the plugging portions 32.