Electrically Heated Catalyst Inner Pipe Insulation

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Solution Overview

Problem

Existing electrically heated catalyst systems face challenges in preventing electricity from flowing to a case due to particulate matter adherence, which can lead to incomplete oxidation and increased risk of electrical discharge.

Innovation Solution

The system incorporates a heat generation element, inner and outer mats, and a specially designed inner pipe with inclination portions and bent sections to insulate electricity and promote heat transfer, while reducing particulate matter adherence and turbulence, using ceramic fiber mats and heat transfer portions to enhance temperature differences and oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a labyrinth structure is adopted to prevent particulate matter inflow, then electrical insulation is improved, but exhaust gas flow and heat transfer are restricted

Engineering Contradiction:

Improveelectrical insulationVSAvoidinner pipe temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The inner pipe is divided into multiple sections with different functions: a smooth section for maintaining electrical insulation, and an inclined section for promoting particulate matter oxidation. This segmentation allows each section to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inclined portion acts as an intermediary structure that facilitates controlled exhaust gas flow between the inner pipe and case, enabling heat transfer and particulate matter oxidation while maintaining overall electrical insulation through the mat structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the inner pipe inside diameter is reduced upstream to prevent particulate matter inflow, then electrical insulation is improved, but exhaust gas flow and heat transfer are restricted

Engineering Contradiction:

Improveelectrical insulationVSAvoidparticulate matter oxidation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Different sections of the inner pipe are given different qualities: the upstream section has reduced diameter for insulation, while the downstream inclined section has increased diameter and specific angle for oxidation efficiency. This local differentiation resolves the contradiction between insulation and oxidation productivity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The inner pipe incorporates an inclined portion with a specific angle (10-30 degrees) that creates a curved flow path, optimizing exhaust gas flow dynamics to enhance particulate matter oxidation while maintaining electrical insulation in other sections.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If mats are extended to cover the entire inner pipe, then electrical insulation is improved, but heat transfer and particulate matter oxidation are restricted

Engineering Contradiction:

Improveelectrical insulationVSAvoidexhaust gas temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The mat coverage is segmented rather than continuous: mats are placed at specific locations (upstream and downstream of the heat generation element) to provide electrical insulation, while leaving the inclined portion exposed to maximize heat transfer and particulate matter oxidation efficiency.

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 configuration effectively suppresses electricity flow to the case, promotes particulate matter oxidation, and ensures efficient heat transfer, thereby preventing particulate matter invasion and enhancing catalyst performance.

Implementation Method 1

a heat generation element that is electrically energized to generate heat

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

an inner pipe that is arranged between said heat generation element and said case for insulating electricity; an inner mat that is arranged between said heat generation element and said inner pipe to insulate electricity

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Implementation Method 3

a downstream side inclination portion that is arranged at the downstream side of said tubular portion with an inside diameter thereof becoming smaller in a direction toward a downstream side

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS9181833B2Electrically heated catalyst

Publication Date: 2015.11.10 TOYOTA JIDOSHA KK

AI summary

Electricity is suppressed from flowing to a case of an electrically heated catalyst. In the electrically heated catalyst which is provided with a heat generation element adapted to be electrically energized to generate heat, the case in which the heat generation element is received, an inner pipe arranged between the heat generation element and the case for insulating electricity, an inner mat arranged between the heat generation element and the inner pipe, and an outer mat arranged between the inner pipe and the case, the inner pipe includes a tubular portion that is arranged in the surrounding of the heat generation element and is formed in parallel to a central axis of the heat generation element, and a downstream side inclination portion that is arranged at the downstream side of the tubular portion, with an inside diameter thereof becoming smaller in a direction toward a downstream side. A downstream side bent portion, being a boundary between the tubular portion and the downstream side inclination portion, is formed in the vicinity of a downstream side end portion of the outer mat.