Exhaust Temperature Control for Particulate Filter Regeneration

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Solution Overview

Problem

Internal combustion engine after-treatment systems face challenges in maintaining sufficient exhaust temperature for hydrocarbon oxidation and particulate filter regeneration, leading to potential clogging and reduced efficiency.

Innovation Solution

A method is implemented to determine if the outlet temperature of exhaust gas from the oxidation catalyst is below a certain threshold, measuring the duration of this condition and elevating the temperature by adjusting engine parameters such as injection timing, EGR system settings, and throttle valve position to ensure effective regeneration of the particulate filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the exhaust temperature is maintained at a low level to reduce thermal stress on engine components, then the longevity of engine components is improved, but the hydrocarbon oxidation efficiency in the after-treatment system deteriorates

Engineering Contradiction:

Improvelongevity of engine componentsVSAvoidhydrocarbon oxidation efficiency

Core Design Contradiction:

Duration of action of stationary objectVSProductivity

Solution Approach 1:

The after-treatment system is segmented into distinct functional zones: a hydrocarbon doser section for fuel injection, an oxidation catalyst section for combustion, and a particulate filter section for soot capture. This segmentation allows low-temperature hydrocarbon dosing to occur separately from the high-temperature oxidation and filtration processes, enabling component longevity while maintaining oxidation efficiency through spatial separation of thermal zones.

Inventive Principle:

Principle #1Segmentation

2Productivity

If the exhaust temperature is increased to improve hydrocarbon oxidation and particulate filter regeneration, then the oxidation efficiency is improved, but the thermal stress on engine components increases

Engineering Contradiction:

Improveoxidation efficiencyVSAvoidthermal stress on engine components

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

Hydrocarbons are dosed into the exhaust stream in advance, upstream of the oxidation catalyst, allowing the fuel to be introduced and mixed with exhaust gases before the high-temperature oxidation zone. This preliminary dosing action enables the hydrocarbons to be ready for combustion at the optimal location, achieving efficient oxidation and filter regeneration while controlling where thermal stress occurs in the after-treatment system rather than in the engine components.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the hydrocarbon dosing rate is increased to ensure sufficient fuel for oxidation and regeneration, then the regeneration effectiveness is improved, but the risk of incomplete combustion and clogging increases

Engineering Contradiction:

Improveregeneration effectivenessVSAvoidrisk of incomplete combustion and clogging

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system incorporates feedback control through oxygen sensors that monitor the oxidation catalyst's oxygen storage capacity and adjust the hydrocarbon dosing rate accordingly. When the catalyst is saturated and cannot store additional oxygen, the dosing rate is reduced to prevent incomplete combustion. This closed-loop feedback ensures optimal fuel dosing that maintains effective regeneration while preventing clogging from unburned hydrocarbons.

Inventive Principle:

Principle #23Feedback

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 approach ensures timely and efficient regeneration of the particulate filter, preventing clogging and maintaining optimal operating conditions for hydrocarbon oxidation, thereby enhancing the system's performance and longevity.

Implementation Method 1

Internal combustion engine after-treatment systems utilizing a hydrocarbon doser rely on a certain level of exhaust temperature into the after-treatment components before hydrocarbons can be oxidized or combusted

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

particulate filter regeneration

Methodology Applied

Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 3

elevating the temperature of the exhaust gas exiting the oxidation catalyst... ensuring timely and efficient regeneration of the particulate filter, preventing clogging

Methodology Applied

Scientific EffectThermal oxidation: Combustion

Data Source

PatentUS8069656B2Method of controlling hydrocarbon accumulation in a particulate filter under certain operating conditions

Publication Date: 2011.12.06 DETROIT DIESEL CORP

AI summary

One embodiment of the invention includes a method of operating an internal combustion engine system comprising an engine, an oxidation catalyst, and a particulate filter, the method comprising: determining if the outlet temperature of exhaust gas from the oxidation catalyst is below a first temperature, measuring the time that the outlet temperature of exhaust gas from the oxidation catalyst is below the first temperature, determining if the measured time has exceeded a first time period, and if so, elevating the temperature of the exhaust gas exiting the oxidation catalyst.