Electrically Heated Support Slit Design for Resistance Control

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Solution Overview

Problem

Conventional electrically heated catalysts with honeycomb structures experience variations in electrical resistance due to variations in base material volume resistance, leading to inconsistent heating outputs and potential overcurrent issues.

Innovation Solution

An electrically heated support with a pillar-shaped honeycomb structure featuring a combination of first and second slits, where the second slit extends in a different direction to adjust electrical resistance and ensure a consistent energizing path length, is used to stabilize electrical resistance between electrode terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a honeycomb structure is provided with slits to define an energizing path, then electrical heating function is enabled, but electrical resistance between electrode terminals varies due to base material variations

Engineering Contradiction:

Improveelectrical resistance consistencyVSAvoidslit configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The energizing path is segmented into multiple sections by providing both first slits (extending in a first direction) and second slits (extending in a second direction different from the first). This segmentation creates a more controlled current path that compensates for base material resistance variations, thereby improving electrical resistance consistency between electrode terminals

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the honeycomb structure are given different slit characteristics - first slits extend in one direction while second slits extend in another direction. This local differentiation of slit orientation and distribution creates zones with specific electrical resistance characteristics that collectively achieve more uniform overall resistance

Inventive Principle:

Principle #3Local quality

2Ease of operation

If constant voltage is applied between electrode terminals, then heating operation is simplified, but input power varies due to electrical resistance variation causing insufficient heating

Engineering Contradiction:

Improvevoltage control simplicityVSAvoidheating output consistency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The electrical resistance parameter of the honeycomb structure is modified by introducing second slits with different orientation and positioning. This changes the overall resistance characteristic of the energizing path, ensuring that when constant voltage is applied, the resulting power input (P=V²/R) remains consistent and achieves the designed heating output

Inventive Principle:

Principle #35Parameter changes

3Productivity

If electrical resistance is lower than specified value, then current flow is increased, but overheating risk increases

Engineering Contradiction:

Improvecurrent flow efficiencyVSAvoidoverheating risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

Second slits are preliminarily introduced into the honeycomb structure to increase electrical resistance before operation. This preliminary anti-action counteracts the tendency toward excessive current flow and overheating by pre-establishing appropriate resistance characteristics in the energizing path

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The second slits, which may appear to add structural complexity, actually convert the potential harm of excessive current into benefit by providing controlled resistance that prevents overheating while maintaining efficient power transmission for heating

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 effectively suppresses variations in electrical resistance, ensuring a reliable designed output and more uniform heat generation, reducing the risk of overheating and improving the structural integrity of the honeycomb structure.

Implementation Method 1

the honeycomb structure is heated by passing an electric current through a pair of electrode terminals

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11672051B2Electrically heated support, exhaust gas purifying device and method for producing electrically heated support

Publication Date: 2023.06.06 NGK INSULATORS LTD

AI summary

An electrically heated support according to the present invention includes: a pillar shaped honeycomb structure, the honeycomb structure including an outer peripheral wall and a partition wall, the partition wall defining a plurality of cells, each of the cells penetrating from one end face to other end face to form a flow path; and a pair of electrode terminals provided on a surface of the outer peripheral wall. In a cross section of the honeycomb structure, the honeycomb structure includes: a plurality of first slits arranged, the first slits being configured to define an energizing path; and a least one second slit located in the energizing path, the second slit extending in a different direction from that of the first slits. A length of the energizing path from one electrode terminal to the other electrode terminal is longer than a diameter of the honeycomb structure.